Translated by T. A. Lab., Inc., Japan, Sept., 2019

RA2008-4

Railway Accident Investigation Report

Train Derailment Accident, between Sagoshi Station and Kita-Amarume Station, Uetsu Line, East Japan Railway Company

Adopted on March 27,2008, and published on April 2, 2008 by the Aircraft and Railway Accident Investigation Commission, Japan

Railway Operator : East Japan Railway Company Accident type : Train derailment Date and time : About 19:14, December 25, 2005 Location : Between Sagoshi station and Kita-Amarume station, at around 158,158 m from the origin at Niitsu station, Uetsu Line, Shonai Town, Higashi-Tagawa District, Yamagata Prefecture, Japan

Notes : 1. This manuscript is an English version of the railway accident investigation report issued by the Aircraft and Railway Accident Investing Commission, ARAIC, and translated by T. A. Lab. Inc., Japan. In this manuscript, the exact but complicated expressions in the original Japanese investigation report are partly revised and translated to relatively plain English for easy understandings. Therefore, this is NOT the official investigation report of the ARAIC. The original Japanese investigation report should be cited for the exact comprehension about the accident. 2. "The objective of the investigation conducted by the ARAIC, in accordance with the Act for Establishment of the ARAIC, is to determine the causes of a railway accident and damage incidental to such an accident, thereby preventing future accidents and reducing damage. It is not the purpose of the investigation to apportion blame or liability", as declared in the original investigation report issued by the ARAIC. 3. The following expressions were used as the terms to describe analytical results in the manuscript following the official translation of the investigation reports by the ARAIC. [1] "It is certain that ....." is used when the analyzed results can be declared. [2] "It is highly probable that ....." is used when the analyzed results are almost correct but could not be declared. [3] "It is probable that ....." is used when the analyzed results have high possibility. [4] "It is somewhat likely that ....." is used when the analyzed results have possibility.

* All figures and photographs in this manuscript were quoted from the "Railway accident investigation report RA2008-4", issued by the ARAIC, and modified to translate Japanese descriptions into English.

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CONTENTS

1. PROCESS AND PROGRESS OF THE RAILWAY ACCIDENT INVESTIGATION ...... 1 1.1. Summary of the Railway Accident ...... 1 1.2. Outline of the Railway Accident Investigation ...... 1 1.2.1. Organization of the Railway Accident Investigation ...... 1 1.2.2. Implementation of the Investigation ...... 2 1.2.3. Comments from Parties Relevant to the Cause ...... 2 2. FACTUAL INFORMATION ...... 2 2.1. Process of the Train Operation ...... 2 2.1.1. Process of the Train Operation ...... 2 2.1.2. Statements of the Train Crews ...... 3 2.1.3. Statements of the Passengers Encountered the Accident ...... 6 2.1.4. Statements of the Traffic Dispatcher etc., in the Niigata Branch Office ...... 11 2.1.5. Statements of the Crews of the Related Trains ...... 13 2.2. Information on the Human Damages...... 15 2.2.1. Summary of the Human Damages...... 15 2.2.2. Number of Casualties in each Vehicle ...... 16 2.2.3. Seated Positions of the Passengers etc...... 16 2.2.4. Status of the Dead Persons...... 16 2.2.5. Status of the Injured Persons ...... 17 2.2.6. Moved Status of the Passengers etc., by the Impact of the Accident ...... 18 2.3. Information on the Physical Damages ...... 18 2.3.1. Damaged Status in the Tracks and the Railway Structures ...... 18 2.3.2. Damaged Status etc., of the Electric Power Related Facilities ...... 21 2.3.3. Damaged Status of the Vehicles ...... 22 2.3.4. Damaged Status etc., of the Objects Except for the Railway Facilities and the Vehicles ...... 26 2.4. Information on the Train Crews ...... 26 2.4.1. Information on the Concerned Driver ...... 26 2.4.2. Information on the Concerned Conductor ...... 27 2.5. Information on the Railway Facilities etc...... 27 2.5.1. Outline of the Railway Facilities ...... 27 2.5.2. Outline of the Electric Power Facilities etc., in Around the Accident Site ...... 28 2.5.3. Information Memories in the Level Crossing Protection Device ...... 28 2.5.4. Train Protection Radio Device ...... 29 2.5.5. Train Radio Device ...... 30 2.5.6. Anemometer ...... 30 2.5.7. The PreDAS ...... 31 2.5.8. Status of the Inspection etc., of the Railway Structures and the Tracks ...... 31

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2.6. Information on the Vehicles ...... 32 2.6.1. Outline of the Vehicles ...... 32 2.6.2. Structure of the Bogies ...... 32 2.6.3. Remodeling of the Vehicles ...... 32 2.6.4. Inspection of the Vehicles ...... 33 2.7. Information on the Handling Train Operation ...... 33 2.7.1. The Limited Speed ...... 33 2.7.2. The Operation Control ...... 35 2.7.3. Summary of Handling Operation in Abnormal Weather Condition ...... 39 2.7.4. Implemented Status of Operation Control at the Occurrence of the Accident ...... 41 2.7.5. Measures at the Occurrence of the Accident ...... 41 2.8. Information on Weather etc...... 41 2.8.1. The Meteorological Summary on the Accident Day ...... 41 2.8.2. Weather Observation on the Ground ...... 42 2.8.3. Observation of Wind Direction and Wind Speed in around the Accident Site ...... 43 2.8.4. Observation by the Meteorological Rader ...... 44 2.8.5. Observation by the Wind Profilers ...... 44 2.8.6. Damaged Status due to Strong Wind in around the Accident Site ...... 45 2.8.7 Information from the Persons etc., Relevant to Weather etc., at the Occurrence of the Accident ...... 47 2.8.8. The Phenomena to Cause the Damages due to Strong Wind ...... 47 2.9. Information on the Evacuation and the Rescue Activities ...... 49 2.9.1. Actions of the Train Crews just after the Occurrence of the Accident ...... 49 2.9.2. Actions of the Train Dispatcher just after Occurrence of the Accident ...... 49 2.9.3. Actions of the Company just after the Occurrence of the Accident ...... 50 2.9.4. Actions of the Emergency Rescue Organization etc...... 51 2.10. Information on the Train Protection etc...... 52 2.10.1. Outline of the Train Protection ...... 53 2.10.2. Handling of the Train Protection ...... 53 2.10.3. Handling of the Train Protection Radio Device by the Conductor ...... 54 2.10.4. Contents of the Education on the Train Protection in the Company ...... 55 2.10.5. Handling of Train Protection Radio Device by Train Crews of the Concerned Train . 55 2.10.6. Handling of Train Protection by the Crews of the Concerned Train ...... 55 2.10.7. Status of the Operation Suspension by the Train Dispatcher ...... 56 2.10.8. Status of the Opposite 831D Train ...... 56 2.10.9. Status of the Following Train ...... 56 2.10.10. Outline of the Measure for Preventing Wheel Rolling ...... 56 2.10.11. Handling on Measure for Preventing Wheel Rolling ...... 56 2.10.12. Contents of the Company's Education on the Measure for Preventing Wheel Rolling ...... 57

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2.10.13. Handling of the Measure for Preventing Wheel Rolling by the Concerned Driver ... 57 2.11. The past railway accidents etc., caused by strong wind ...... 58 2.11.1 Train Derailment Accident in Tozai Line of the Teito Rapid Transit Authority ...... 58 2.11.2. Train Derailment Accident in San-in Line of the Japanese National Railways ...... 58 2.11.3. Train Derailment Accident in Nemuro Line of the Hokkaido Railway Company ...... 60 2.11.4. Train Derailment Accident in South Rias Line of the Sanriku Railway Co. Ltd...... 60 2.11.5. Train Derailment Accident in Kosei Line of the Japan Freight Railway Company ..... 61 2.11.6. Train Derailment Accident in Chikuhi Line of the Kyushu Railway Company ...... 61 2.11.7. The Windbreak Fences etc., of the Company ...... 62 2.12. Experiments etc., to Determine the Facts ...... 63 2.12.1. Investigation and Analysis of the Wind Speed etc...... 63 2.12.2. Calculation of the Critical Wind Speed of Overturning ...... 67 2.12.3. Trial Calculation of the Critical Wind Speed of Overturning by Simple Equation ..... 73 3. REASONS TO IDENTIFY THE FACTUAL INFORMATION ...... 74 3.1. Analysis on the Railway Facilities ...... 74 3.1.1. Analysis on the Causes of the Derailment ...... 74 3.1.2. Analysis on the Traces in the Railway Facilities ...... 74 3.2. Analysis on the Vehicles ...... 76 3.2.1. Analysis on the Factors of the Derailment ...... 76 3.2.2. Analysis on the Damages in the Vehicles ...... 76 3.3. Analysis on the Handling Train Operations ...... 77 3.4. Analysis on the Weather Condition etc...... 77 3.4.1. Analysis on the Results of Weather Observation ...... 77 3.4.2. Analysis on the Damages by Strong Wind in around the Accident Site ...... 78 3.4.3. Analysis on the Weather Condition in the Accident Site ...... 79 3.5. Analysis on Factors of the Derailment and the Vehicle Behaviors before and after the Derailment ...... 81 3.5.1. Analysis on the Running Velocity in around the Accident Site ...... 81 3.5.2. Analysis on the Operation Control in around the Accident Site ...... 81 3.5.3. Analysis on the Critical Wind Speed of Overturning ...... 81 3.5.4. Analysis on the Occurrence of the Derailment of the Vehicles ...... 82 3.5.5. Analysis on the Behavior of the Vehicles before and after Derailed ...... 83 3.6. Analysis on the Survival Factors ...... 87 3.6.1. Analysis on the Causes of Death and Injuries ...... 87 3.6.2. Analysis on the Actions of the Emergency Rescue Organization etc...... 87 3.7. Analysis on the Train Protection ...... 88 3.7.1. Analysis on the Handling of Train Protection by the Crews of the Concerned Train .... 88 3.7.2. Analysis on the Handling of the Train Protection etc., Prescribed in the Company ...... 89 3.8. Analysis on the Concept of the Measures against Strong Wind ...... 90 3.8.1. The Effective Use of the Weather Information ...... 90

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3.8.2. Implementation of the Measures against Strong Wind ...... 91 3.9. Summary of the Results of the Analysis ...... 91 3.9.1. Analysis on the Railway Facilities ...... 91 3.9.2. Analysis on the Vehicles ...... 91 3.9.3. Analysis on Handling Train Operation ...... 92 3.9.4. Analysis on the Weather etc...... 92 3.9.5. Analysis on Factors of the Derailment and Vehicle Behaviors before and after the Derailment ...... 93 3.9.6. Analysis on the Survival Factors ...... 94 3.9.7. Analysis on the Train Protection Procedures ...... 94 3.9.8. Analysis on the Concept of the Measures against Strong Wind ...... 94 4. PROBABLE CAUSES ...... 95 5. REMARKS ...... 95 5.1. Studies on the Measures against Strong Winds ...... 95 5.2. Research on the Measures against Gust of wind ...... 96 6. ACTIONS TAKEN ...... 96 6.1. Measures Taken by the Company ...... 96 6.2. Measures Taken by the Ministry of Land, Infrastructure, Transport and Tourism ...... 97 6.3. Measures Taken by the Japan Meteorological Agency ...... 97

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1. PROCESS AND PROGRESS OF THE RAILWAY ACCIDENT INVESTIGATION

1.1. Summary of the Railway Accident On Sunday, December 25, 2005, the inbound Limited Express 2014M train, named as "Inaho 14", composed of 6 vehicles started from Akita station bound for Niigata station of the East Japan Railway Company, departed from Sakata station about 68 minutes behind the scheduled time 18:00. While the train was running in the straight embankment structure track section after passed the No.2 Mogamigawa Bridge, all vehicles derailed at about 19:14. From the 1st to the 3rd vehicles fell from the embankment and turned over on their sides, and the 1st and the 3rd vehicles had collided with the buildings in the left side of the railway track. Here, the words left/right" and "front/rear" were based on the running direction of the train, and vehicles are numbered from the front. There were 43 passengers, 2 train crews and an on-train sales staff. Among these, 5 passengers were dead and 33 persons, i.e., 31 passengers, a train crew and an on-train sales staff, were injured.

1.2. Outline of the Railway Accident Investigation 1.2.1. Organization of the Railway Accident Investigation The Aircraft and Railway Accident Investigation Commission, hereinafter referred as the "ARAIC", designated the Chief Investigator and 5 railway accident investigators to engage in the investigation of the concerned railway accident, on December 25, 2005. The ARAIC also designated additional 3 railway accident investigators on January 4, 2006, April 1, 2007, November 29, 2007, respectively. In addition, the ARAIC dispatched the Chairman, the Board Members, the professional members, the railway accident investigators, etc., to the accident site etc., to implement the investigation. On February 7, 2006, the ARAIC appointed Professor H. Niino, Department of Physical Oceanography, Atmosphere and Ocean Research Institute, The University of Tokyo, as the professional member engaged in the investigation of the concerned accident and designated the meteorological analysis as the engaged area to be investigated. The Tohoku Transport Agency dispatched its staffs to the accident site to support investigation of the concerned accident. In addition, the factual investigation was implemented in cooperation with the Japan Meteorological Agency, hereinafter referred to as "the JMA". The investigation and the analysis on the wind speed etc., and the estimation of the critical wind speed of overturning were entrusted to the Foundation, Railway Technical Research Institute. To implement the investigation, hearing opinion from Professor Y. Tamura, Department of Architecture, Faculty of Engineering, Tokyo Polytechnic University, was implemented.

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1.2.2. Implementation of the Investigation 2005 Dec. 26 to 31, Investigation of the accident site and hearing statements Dec. 27,2005 to Mar. 16, 2007 Investigation and analysis of wind speed etc. 2006 Jan. 5 Installation of anemometers for verification Jan. 5 to 6, Jan.31 to Feb.1, Investigation of weather Mar.2 to 3 Jan. 6 to 8, Jan. 30 to Feb. 1, Investigation of the vehicles May 22 to 24 Jan. 20 to 21 Investigation of the accident site, Installation of anemometer in the accident site Feb. 28 to Mar. 1 Hearing statements Apr. 11 to 13 Investigation of the track June 13 to 14 Investigation of the track and the test of anemometers June 19 to Nov. 30 Measuring test of aerodynamic forces and estimation of the critical wind speed of overturning Sep. 22 to 25, Nov. 12 to 14 Measurement of the gravity centers of the vehicles 2007 Sep. 7 to Nov. 20 Questionnaire for the injured persons and hearing statements 2008 Jan. 11 Investigation of the tracks and the vehicles Jan. 21 Hearing statements

1.2.3. Comments from Parties Relevant to the Cause Hearing opinions for the investigation report, from persons concerned with probable causes were implemented.

2. FACTUAL INFORMATION

2.1. Process of the Train Operation [Refer to Attached Figures 1, 2] 2.1.1. Process of the Train Operation The outbound Limited Express 2005M train "Inaho 5", hereinafter referred to "the outbound Limited Express train", composed of 6 vehicles and started from Niigata station bound for Akita station of the East Japan Railway Company, hereinafter referred as "the Company", departed from Niigata station on schedule at 12:34. The outbound Limited Express train was suspended its operation at Shimohama station due to the trouble of a point in Araya station, and arrived at Akita station at about 17:15, about 60 minutes behind the scheduled time 16:16. The vehicles used in the outbound Limited Express train were turned back at Akita station and became to the inbound Limited Express 2014M train, "Inaho 14", hereinafter referred as "the concerned train", starting from Akita station bound for Niigata station. The concerned train departed from Akita station at about 17:34, about 60 minutes behind the scheduled time 16:34.

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The concerned train arrived at Sakata station at about 19:06, about 68 minutes behind the scheduled time 17:58, as there was the speed control of less than 25 km/h due to strong wind between Ugo-Ushijima station and Araya station, after departed from Akita station. The concerned train departed from Sakata station at about 19:08, about 68 minutes behind the scheduled time 18:00, after stopped for about 2 minutes.

2.1.2. Statements of the Train Crews [Refer to Attached Figures 1, 2, 3-I, 3-II] The driver and the conductor of the concerned train, hereinafter referred to as "the concerned driver" and "the concerned conductor", respectively, stated as follows. (1) The concerned driver On the accident day, I went to Niigata Transport Office before 11:00, and received the roll call at 11:35. My physical condition was good on the accident day, because the previous day was a holiday. After received the roll call, I was charged in operation of the outbound Limited Express train from Niigata station to Sakata station. When I received the roll call at Sakata station before boarding on the concerned train at about 17:38, there was no instruction about the speed control due to weather condition, as there was the communication that the train had been operated behind schedule. I started the duty of operation of the concerned train at Sakata station about 70 minutes behind schedule, and took over operation of the concerned train with the transfer message as "there was no abnormal situation" from a driver who had operated the concerned train until to Sakata station. It was sleeting and thundered but wind was not felt so strong. I did not conscious about an abnormal wind because there was no abnormal situation such as rolling motion of the vehicles when the concerned train departed from Sakata station at 19:08, or passed though the No.2 Mogamigawa bridge, hereinafter referred as "the concerned bridge". In addition, there was no abnormal situation in the operation of the concerned train. I operated the notch off when the concerned train approached to the concerned bridge in around the accident site, at about 110 km/h. I think the velocity of the concerned train running in around the accident site was about 105 km/h, as I did not watch the speedometer but I had been applied the snow-proof brake*1. As I operated notch off at a little faster velocity as usual, but I operated the notch off at the velocity a little slower than as usual because it was sleeting and there was snow on the track. Just after the concerned train passed the concerned bridge, there was the terrible storm of snow blown up from the ground by the wind from right, and something white wind bumped as to wrap the driving cab. The concerned train tilted to left and turned over in an instant. I did not feel that the concerned train hit something or stepped on something fallen, at that time. I could not afford to implement handling operation because it was the incident in an instant. As I understood that the concerned train stopped as being derailed, I looked for the train protection radio device and the train radio device to prevent the concurrence of the accident, but I could not find them because it was dark in the driving cab. I operated the switch which was considered as the switch of the pantograph emergency dropping device. I looked for the

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crew's bag contained the business mobile phone, but I could not find it because it was dark. After I got out of the vehicle from right door for the crews that was in upward of the turned over vehicle, I asked the passenger who was already got out from vehicle to arrange the ambulance. As I thought that I should implement the train protection procedure, but the driving cab in the 1st vehicle was in the situation that nothing could be done, so that I went to the 6th vehicle and knocked the door for train crews, but the door was locked and the concerned conductor was absent. At this time, I noticed the alarm sound of the train protection radio from the driving cab of the 6th vehicle, I thought that the train protection radio had already been implemented. I did not implement the setting of the rail clamp shunt and ignition of the portable fuse. I thought that it was no need to implement procedure of the prevention of wheel rolling for the 6th vehicle, considering the derailed status. After that, as I found the overhead contact line was in the dangerous status,, I thought that I should arrange the operation suspension of the related trains and implement the stop feeding procedure, so that, I looked for the concerned conductor in around the 6th vehicle to communicate with the train dispatcher. I do not remember when I met with the concerned conductor as I was completely absorbed in running around. When I met with the concerned conductor, I asked the train dispatcher to suspend operation of the related trains, to implement stop feeding and to arrange dispatch of ambulances, using the business mobile phone of the concerned conductor. At that time, I heard from the train dispatcher that the arrangement of the operation suspension had already been implemented. When I went back to the 1st vehicle and looked the cabin, I found the staff of the Company boarded on the concerned train as a passenger, hereinafter refer to as "the passenger C in the 1st vehicle", then I heard from him about the situation of the 1st vehicle. After that, I patrolled all vehicles and checked the number of injured persons and their injured levels, etc. In addition, I guided the passengers, who had already got off the train, to the 6th vehicle until the police and the fire fighters were arrived. After the police and the fire fighters had arrived at the accident site, I went to the hospital by a car of the police. I suffered from lacerations on upper of right eye and bruised legs, in the accident. *1 "Snow-proof brake" is the brake system to prevent the adhesion of snow and ice to the gap between the brake shoe and the wheel by applying the brake of weak level as the brake shoe contacted with wheel, as the braking force would decreased by the reduction of the friction force when the snow or ices were adhered to the gap between the brake shoe and wheel, or between brake lining and disk. (2) The concerned conductor On the accident day, I went to Sakata Transport Office at about 11:30, and received the roll call at about 11:54. I started the duties of the day from Sakata station to Akita station boarding on the Outbound Local 543M train originated from Sakata station bound for Akita station. After that, I was scheduled to engage the duty from Akita station to Niigata station boarding on the concerned train.

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The concerned train departed from Akita station at 17:34, about 60 minutes behind schedule, and arrived at Ugo-Honjo station about 70 minutes behind schedule, as there was the speed control of less than 25 km/h due to the strong wind between Ugo-Ushijima and Araya station. After that, the concerned train stopped at Nikaho station, Kisakata station, Yuza station, and arrived at Sakata station, about 70 minutes behind schedule, and departed from Sakata station at 19:08. After departed from Sakata station, a passenger asked me the time to connect to the Joetsu Shinkansen, then I inquired to the dispatcher by the train radio in the driving cab in the 6th vehicle. Just after answered the results to the passenger, the accident occurred. There was no abnormal situation while the concerned train was running through the concerned bridge, and the operating velocity was as usual. Just after the concerned train passed the concerned bridge, there was the dull sound "donk" as heaved up from the bottom, and the cabin jolted as rattled, then the concerned train stopped suddenly, and the room lights were turned off. As the concerned train stopped at a place where trains never stopped usually, and there was no communication from the concerned driver, I pushed the buzzer for on-train communication to communicate with the concerned driver, but the buzzer did not sound. Then, I operated to send the alarm signal by the train protection radio device. In addition, I operated the train radio device to report the situation to the train dispatcher, but it did not work. Then, I communicated with the train dispatcher by the business mobile phone and reported that I sent the alarm signal from the train protection radio device as the concerned train emergency stopped between Sakata station and Amarume station. As the train dispatcher instructed me to report the precise information on the stopped place and the situation, I answered to report after communicated with the concerned driver because I did not understand the precise situation. While I walked in the cabins toward the front vehicles as checking existence of the injured persons, there was no injured person in the passengers of the 5th and 6th vehicles, as it was dark in the cabins. I returned to the 6th vehicle because I found that the 5th and 4th vehicles had decoupled when I went to the front end of the 5th vehicle. On my return way, I guided 2 or 3 passengers in the 5th vehicle to the 6th vehicle to prevent falling off to outside vehicle. I looked outside vehicle from around the front edge of the 5th vehicle, but I could not see the situation as it was dark. As I was notified from passengers in the 6th vehicle that there were some persons outside of the train, I opened the door for train crews in the rear of the vehicle and looked outside train and found a few passengers and the turned over vehicles. As I found the concerned driver in the persons outside train, I handed my business mobile phone to him and asked to communicate with the train dispatcher. As it was rain at that time, I guided 4 or 5 passengers standing in outside train to the 6th vehicle. After that, I checked the injured status of the injured persons in cooperation with the concerned driver. When I talked to the cabin of the 2nd vehicle through the gap between

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windows of the overturned vehicle and the ground, there was a response as "It is all right". As for the situation in the cabin, the passenger accompanied with me at that moment, hereinafter referred to as "the passenger A in the 2nd vehicle", entered the cabin and checked. Next, I went to the 1st vehicle where the concerned driver was checking. As the passengers in the 1st vehicle told us that it was so cold due to being beaten with snow and rain, I went back to the 6th vehicle to bring blankets. As number of the reserved blankets were insufficient, the on-train sales staff took off the curtain in the cabin and handed to the concerned driver. After the rescue team had arrived, I assisted the rescue staffs to let the injured persons rescued from the 1st vehicle get on the ambulance.

2.1.3. Statements of the Passengers Encountered the Accident The passengers and the Company staffs boarded as the passengers in the concerned train at the occurrence of the concerned accident stated as follows.

2.1.3.1. Passengers [Refer to Attached Figures 1, 2, 3-I, 3-II] (1) The passenger A in the 1st vehicle, female of the twenties. I got on the concerned train from Akita station and sat in the right window side seat in around center of the 1st vehicle. I had been closed my eyes to try to sleep while the concerned train had passed around Sakata station. But I woke up as I heard the sound "pop-pop" as something like sleet were hitting the right window glasses due to snowstorm, just before the accident. Just after that, the vehicle turned to left and collided with something. At that instant, the glasses and sands accompanied to the terrible wind flew from right. My body was blown away to the front of the cabin by the violent impact, I felt pains in my body and suffered by the difficulty in breathing. After that the rescue staffs set me on the stretcher, fastened my whole body and lifted to outside vehicle, then, transferred to the hospital. I was severely injured as broken bones of the cervical vertebrae, a wrist, etc., in the accident. (2) The passenger A in the 2nd vehicle, male of the twenties. I got on the concerned train from Akita station, and I remember to sit in the right window side seat of about 7th row from the front of the 2nd vehicle. When the concerned train arrived at Sakata station, it seemed that the weather was stormy. There were the sound as snow and sleet hit the vehicle due to the snowstorm, and I felt the sound became severe after the concerned train had departed from Sakata station. It was thundered also. The accident occurred just after the vehicle was considered as passed the concerned bridge. I felt that the vehicle body was raised up as heaved up as "whump" at first, and the room lights were turned off. After that, the vehicle had tilted to left as being accelerated and the train had stopped with the violent sound as collided with something. I am not sure, as it had occurred in an instance, but I remember that the vehicle did not yet turned over when the vehicle jolted at first and room lights turned off. I think it took about ten

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some seconds until the severe jolt had calmed down. I understood that the vehicle had turned over when the concerned train had stopped. I reported to Sakata Fire Station by my cellular phone about 3 to 4 minutes after the occurrence of the accident. In addition, I called the fire station where I was working, and asked to report to the Company to prevent the secondary disaster. After that, I implemented the first-aid treatments such as the hemostats of the blooding passengers, etc. As there was the gap as large as an adult could pass though, I went out of the vehicle through the gap. I told the persons in the cabin that to wait for the rescue as being stayed in the cabin because it was cold outside vehicle. It was severe wind as the screams and voices were lost by the snowstorm. After the ambulances and the fire engines were arrived, I had been assisted the rescue team such as transportation of the patients etc., but I was noticed that I was injured, so that I was transported to the hospital. I had severely injured from the contusion of my knees, etc., in the accident. (3) The passenger B in the 2nd vehicle, male of the twenties. I got on the concerned train from Akita station, and sat in the right window side seat of the 3rd row from the front in the 2nd vehicle. When the concerned train departed from Sakata station, it was violent snowstorm as made the sound to hit the window glasses. After the concerned train departed from Sakata station, I was looking outside windows or preparing the e-mail, etc. I am not sure the precise position because it was the first time for me to take this route, the vehicle suddenly tilted to left and after the vibration and sound as if the train was running on the sleepers continued for 2 to 3 seconds, the vehicle overturned and the room lights turned off. At this moment, I tried to hold the handrail of the left seat, but I could not catch it. After that I was thrown out to the seats in left side of the aisle and fell on my back as my head in the direction of the train. After a while, I went to backward and crawled out through the gap between the ground and the window that was in the bottom of the overturned vehicle and the glass was broken. I got out from the vehicle about 30 minutes after the occurrence of the accident, the rescue team were already arrived, I was treated the first aid in the ambulance and transported to the hospital. I was severely injured by the lacerations on my head and broken costal bones, etc., in the accident. (4) The passenger C in the 2nd vehicle, male of the forties. I got on the concerned train from Akita station, and sat in the left window side seat of the 5th row from the rear in the 2nd vehicle. I remember that it was violent wind and something as hail or rain were violently hitting windows when the concerned train departed from Sakata station. While the concerned train was passing the concerned bridge and I was spending time vacantly in the cabin, the sound as rattling had occurred and the cabin became to utter dark. I did not know what happened after

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that, but I thought that I should got out of the vehicle promptly because I thought that the vehicle had fallen into Mogamigawa river, then I escaped from the vehicle through the window that the glass was broken. After that I was guided by the concerned conductor and waited in the 6th vehicle and transported to the hospital after the ambulance had arrived. I was severely injured by the lacerations on my head and the contusion of the whole body, etc., in the accident. (5) The passenger D in the 2nd vehicle, male of the forties. I got on the concerned train from Akita station, and sat in the rear left window side seat in the 2nd vehicle. After the concerned train departed from Akita station, it was violent wind as to change the velocity of the train in around Yuza station. The weather was not so severe when the concerned train was stopping at Sakata station, but after the concerned train departed from Sakata station and running in the area where the streetlights etc., could not be in sight, it was violent wind and the lightnings were found in a distance. While the concerned train was passing through the concerned bridge, I moved my eyes from the book to the outside of the train vacantly as I felt that the train was running through the bridge, there were sound and vibration as "budda-budda" from the downward, and the vehicle suddenly tilted to left as wobbled. The tilted vehicle overturned to about 90 degrees and seemed to stop suddenly as being fallen over on the ground. When the vehicle was overturning, I prepared to the impact due to the collision by holding the seat back of the front seat in the forward bent posture. I got off the vehicle through the gap between the ground and the window that was in the downward of the overturned vehicle and the glass was broken, after the concerned train had stopped. Some four passengers got off the vehicle followed me, and one of the passengers had reported to the police using the mobile phone. It was violent wind and thundering at that time. As one of the passengers got off the 2nd vehicle was in the status of hard to breathing, I was treating the passenger at outside of the train for a while. As the 6th vehicle had been remaining on the rail, I got on the 6th vehicle in cooperation with the passenger. After that, I was transported to the hospital by the ambulance. I was severely injured as the contusion of my left arm and broken costal bones in the accident. (6) The passenger A in the 3rd vehicle, male of the thirties. I got on the concerned train from Akita station, and took a seat in the 2nd vehicle. After the train departed from Sakata station, I was standing near the right door for getting on and off for passengers in the front deck of the 3rd vehicle, after moved from the seat as the train was approaching to the station of my destination. I was looking outside of the vehicle while the concerned train passed the concerned bridge, the strong wind, as violent as to enlarge the gap between right door for the passengers and the vehicle body, were entered the deck through the gaps. After that, the vehicle rolled and tilted to right, and the tilted angle increased gradually and the room lights were turned off, then, I

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hold as cling the handrail in around the door for passengers. When the vehicle overturned to about 90 degrees, the trash box equipped by the left door for passengers fell off. The vehicle, in the status of being fallen on its side completely, slid on the ground as "rat-tat-tat", and something like earth and sand entered from the coupling part between the 2nd and the 3rd vehicles. When I got off the vehicle from the coupling part with the 2nd vehicle, I found that the 2nd vehicle had been halted in a distance from the 3rd vehicle. When I climbed up to the embankment to comprehend the situation of the surroundings, I found a few passengers getting off from the 1st and the 2nd vehicles. After that the concerned conductor guided me to take refuge to the 6th vehicle. The concerned driver had been checking the status of the injured persons as being bleeding from his head. After a while, the ambulances and the police had arrived, and I was transported to the hospital. I was injured as the contusion of my left leg, in the accident. (7) The passenger A in the 6th vehicle, female of the thirties. I got on the concerned train from Akita station, and sat in the left window side seat in the 3rd row from the rear in the 6th vehicle. The weather at Sakata station was a little rain but not so severe. While the concerned train was running after departed from Sakata station, the snow was hitting the window glasses. I was not sure whether the concerned train had passed though the concerned bridge or not, but while I was surprised for the strong wind from right, the vehicle suddenly stopped as pitched forward and bounded three or four times. My body was bumped strongly to the seats and the walls. Furthermore, it was so cold in the cabin after the accident, I had a stomachache and could not stand up. After that I was transported to the hospital by the ambulance. I suffered a whiplash injury in the accident.

2.1.3.2. The Company staffs boarded on the concerned train as the passenger [Refer to Attached Figures 1, 2, 3-I, and 3-II] (1) The passenger B in the 1st vehicle, male of the forties I got on the concerned train from Sakata station, and sat in the left window side seat in the 4th or 5th row from the front in the 1st vehicle. The weather at Sakata station was a light snow as usual. Thunders were rumbling 2 to 3 times after the concerned train departed from Sakata station. After the concerned train had passed the concerned bridge, the strong wind blew from right, and I heard the sound "pop-pop" as something hit the window glasses. After that, the vehicle began to tilt to left, in an instant when I felt that the vehicle tilted larger than as usual, the vehicle fell on the sleepers and ran as rattling and overturned. It was not so long time that the vehicle was running as rattling. When the vehicle had overturned, the left window glasses were broken into pieces, at the same time, the snow entered the cabin. After that I lost my consciousness. When I recovered consciousness, I was thrown in forward and could not move my body as

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being caught by something, and my whole body was covered by snow as if I encountered the avalanche. As I could move my hands and legs a little, I could slip out from the snow. The 1st vehicle had overturned to left and the right side of the vehicle body was in upward, but I could not get out of the vehicle as the upward window glasses were broken. There were about seven passengers including me in the cabin. I heard the voice of young lady as "Ouch! help me!", then, I implemented the rescue activity in cooperation with the other passengers. After we rescued two young ladies, it was violent rain, and it was cold as I was drenched to the skin. As I could not get out of the vehicle by myself, I was lifted using the belt for rescue. As my left leg could not be moved, I was transferred to the ambulance being assisted the shoulder of the rescue staff. I was severely injured the damages of the cervical vertebrae, etc. (2) The passenger C in the 1st vehicle, male of the twenties. I got on the concerned train from Sakata station, and sat in the left window side seat in the 5th or 6th row from the front in the 1st vehicle. The wind was not so strong as it was rain and thundering when the concerned train departed from Sakata station. While the concerned train was passing the concerned bridge, there was severe lightnings but did not heard thunders. It was hailing occasionally. When the accident had occurred, the vehicle floated into air just as the takeoff of the airplane, before overturned. After that, the vehicle tilted to left and the cabin became to utter dark, I heard the terrible sound as "rat-tat-tat", when I recovered consciousness, the vehicle had been overturned. I think it is about 5 seconds from being floated to hear the terrible sound. I heard the sound as "rat-tat-tat" for about 2 to 3 seconds. When I recovered consciousness, the door of the driving cab was in front of my eyes, then, I think I was thrown to the seats of the 2nd or 3rd row from the front. As there was no sound in around, I talked to the around "is it all right?". As the time passed, I could hear the voices from the circumference and became to see the dark cabin gradually. Soon after that, I heard the female voice to ask the help. As I find the hand of the woman beneath the male passenger, I rescue the female buried in the snow and soil in cooperation with the other passengers. At that time, it was cold as being drenched by the violent rain entered the cabin through the windows where glasses were broken. After a while, the concerned conductor talked from outside of the vehicle, I asked him to bring something to warm ourselves as the blanket. In addition, I asked the rescue staff who arrived at that time, to bring an oxygen cylinder for the woman who was breathing hard. I was rescued from the window in the upward of the overturned vehicle and transferred to the hospital by the ambulance. I was seriously injured as the contusion of the whole body and the laceration of right hand, etc., in the accident. (3) The passenger D in the 1st vehicle, male of the forties. I got on the concerned train from Sakata station and sat in the left window side seat a little forward from the center of the 1st vehicle.

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The weather at Sakata station was thundering, strong wind and cold. It was the similar weather after the concerned train departed from Sakata station. After a while the concerned train had passed the concerned bridge, I felt the vehicle floated a little, then the vehicle ran with the rattling sound as wheels were running on the concrete sleepers, and all room lights were turned off suddenly. The vehicle was falling down the slope diagonally to left in the dreadful acceleration. I had lost my consciousness once, and after I recovered consciousness I communicate to my home by the mobile phone, it was 19:41. As I could not move my body due to the pain in my back when I tried to move the body, I was lifted by the rope for rescue to get off the vehicle. After that, I was transferred to the hospital by the ambulance. I was seriously injured as the broken bone of the lumbar vertebrae and the breastbone, and broken ligament of left shoulder in the accident. (4) The passenger E in the 2nd vehicle, male of the twenties. I sat in the right window side seat in the 2nd vehicle. I was looking for my mobile phone and did not see outside of the vehicle before the accident. I did not remember that the concerned train had passed the concerned bridge. When the accident occurred, I felt that the vehicle once floated and fell down as passing through the low step by a car, after that, I was pushed to the chair back of the front seat due to the longitudinal vibration, then I turned my body to lateral direction. I did not remember what happened after that. When I recovered consciousness, my body was caught by the armrest of the aisle side seat in the left. I got out from the vehicle through the gap between ground and the window in the bottom of the overturned vehicle and moved to the 6th vehicle. While I was waiting in the 6th vehicle, it was strong wind violent as the vehicle was rolling occasionally. I was injured by the severe whiplash, etc., in the accident.

2.1.4. Statements of the Traffic Dispatcher etc., in the Niigata Branch Office [Refer to Attached Figures 1, 2] The train dispatcher, the chief dispatcher and the supervisory dispatcher, who engaged in the section around the accident site at the occurrence of the accident, stated as follows. (1) The train dispatcher On the accident day, I had been seated in the dispatcher's desk for Uetsu Line, between Nezugaseki station and Sakata station, and Rikuu-Saisen Line, hereinafter referred as "the Uetsu CTC". It was possible to comprehend the delay of the train operation in the district of Akita Branch by the TID*2, installed in the Uetsu CTC. The outbound limited express, that was scheduled to be the concerned train after turned back at Akita station, departed from Akita station about 60 minutes behind schedule, as the arrival at Akita station had delayed by the operation suspension at Shimohama station due to the trouble of the switch in Araya station. At about 19:14, there was the communication from the electric power dispatcher to check the situation as the power feeding had been disconnected. While I had been checking the trains

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running in the related section using the check timetable, the other train dispatcher tried to communicate with the concerned driver to check the situation using the train radio at about 19:16, but there was no response. At that moment, the business mobile phone in the Uetsu CTC received the call from the concerned conductor to communicate the first report as "I could not communicate with the concerned driver. The room lights were turned off together with the impact. I operated the train protection radio device to send the alarm signal". As I heard the occurrence of the abnormal situation and the operation of the train protection radio device to send the alarm signal, I arranged the operation suspension of the related trains immediately. The concerned conductor called again to report as "the train seemed as being derailed, but I do not know about the pole number and the track section because it is dark". At about 19:30, the concerned driver telephoned us as "It was a gust of wind on the bridge, the train had derailed. The front 3 vehicles were completely demolished, many persons were injured, please arrange to dispatch the ambulances". As I asked the precise position, he replied as "Between Amarume station and Kita-Amarume station, Pole No.10. I am slightly injured, but there were passengers who are bleeding". I instructed him to comprehend the injured status of the passengers in cooperation with the concerned conductor and told to him that the operation suspension of the related trains had been arranged. Here, there was no operation suspension in around the accident site, on the accident day. *2 "TID" is the abbreviation of the Traffic Information Display, which is the device to transfer automatically the information on the position of the trains etc., to each station and the section office, in the concerned section. The TID was used for the guidance for passengers and for the change of the arrangement of the operation scheduling of vehicles, etc. (2) The chief dispatcher The concerned train was operating behind schedule because the outbound limited express train, that was scheduled to be the concerned train after turned back at Akita station, had delayed due to the trouble of the switch in the district of Akita Branch Office. I arranged the operation suspension of the related trains, responding to the first report of the accident notified to the business mobile phone of the Uetsu CTC from the concerned conductor. In addition, I asked the supervisory dispatcher to inform the police and the fire station, and instructed Sakata station to gather the staffs after explained the situation, as I understood the derailment of the concerned train from the conversation using telephone between the train dispatcher and the concerned conductor. There was no operation control due to the strong wind at the time of the accident. In addition, there was no report on the abnormal weather condition etc., from the train crews in the time slot of the occurrence of the accident. (3) The supervisory dispatcher I received the first report of the accident about at 19:16, from the train dispatcher in the Uetsu CTC. I received the second report as the concerned train seemed to be derailed, at about 19:20, then I made a telephone to the Police Headquarters of Yamagata Prefecture to explain the

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situation and to ask dispatch of the policemen and arrangement of the ambulance, but I was told that the police was already informed by the 110 call. After that, I instructed the operation suspension of the related trains, and communicated information in the dispatcher's room and informed to the related sections of the Niigata Branch Office, about the occurrence of the derailment accident in Uetsu Line, after confirmed that the arrangement of operation suspension had been implemented. There was no alarm sound for Uetsu Line in the PreDAS*3, on the accident day. *3 "PreDAS" is the abbreviation of the Prevention of Disaster Alarm System of the company. Refer to 2.5.7.

2.1.5. Statements of the Crews of the Related Trains [Refer to Attached Figures 1, 2, 3-I and 3-II] The driver of the concerned train from Akita station to Sakata station, the driver of the inbound Local Diesel 162D train, starting from Sakata station bound for Shinjo station and operated preceding the concerned train, hereinafter referred to as "the foregoing train", the crews of the inbound Local Diesel 832D train, starting from Sakata station bound for Niitsu station and operated preceding the foregoing train, hereinafter referred to as "the preceded foregoing train", the crews of the inbound Local Diesel 230D train, starting from Sakata station bound for Nezugaseki station and operated following the concerned train, hereinafter referred as "the following train", and the crews of the outbound Local Diesel 831D train, starting from Niitsu station bound for Sakata station and halting at Amarume station at the time of the occurrence of the accident, hereinafter referred as "the opposite 831 train", stated as follows. (1) The driver of the concerned train operated from Akita station to Sakata station The concerned train arrived as Sakata station about 70 minutes behind schedule because there was the speed limit below 25 km/h due to the strong wind between Ugo-Ushijima station and Araya station, and I operated the braking a little earlier than as usual considering the snow fall, on the way to Sakata station. I did not feel that the wind was not so strong in the section I operated the concerned train on the accident day. I got the impression that the thundering was severe in southern direction before the arrival at Kosagawa station, Kisakata station and Sakata station, but I did not remember the weather when I handed over the train operation at Sakata station. As I saw the lightning many times but did not hear the thunder at all. After the concerned train arrived at Sakata station, I handed over the train operation to the concerned driver as there was no abnormal situation, because there was no abnormal situation as the brake had been working well. In addition, the rolling of the vehicles was not violent and there was no trouble in the devices in the driving desk. I did not feel the dangerousness due to the violent wind during the train operation based on my experience as the driver up to that time. (2) The driver of the foregoing train I did not remember well on the operating status of the foregoing train in the accident day, but I remember that it thundered many times and windy when departed from Sakata station at

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about 18:02 according to the record. I think there was no abnormal situation on the track in around the accident site. I never felt the dangerousness due to the strong wind or the abnormal situation of the track and I think there was no operation control due to the strong wind, while operating the train between Sakata station and Amarume station. (3) The crews of the preceded foregoing train (i) The driver I think that the preceded foregoing train departed from Sakata station on schedule at 17:22. I do not remember the weather at that time in around Sakata station. I did not remember the existence of the abnormal situation in the track when the preceded foregoing train was passing around the accident site. In addition, I do not remember the existence of the strong wing and severe snow while operating the preceded foregoing train. I never felt the dangerousness due to the strong wind in around the concerned bridge and the accident site in the past. When it was severe wind in Shonai district, the operation control due to strong wind will be applied between Atsumi-Onsen station and Uzen-Mizusawa station at first. The strong wind blows everywhere in the track section between Sakata station and Uzen-Mizusawa station, as it was laid out in Shonai Plain. The anemometers had been located on Mogami river etc. In the up track, even if try to accelerate the train from 100 km/h, which is the limited speed in the curved track in around Sagoshi station, the train could not be accelerated to around 110 km/h in the concerned bridge because there was up grade in along the track, then, the train could not be accelerated if it was strong wind. (ii) The conductor It was a little windy but not so strong as worried when I was in the duty of the preceded foregoing train. I could not see the rail from the cabin as it was dark outside, but I felt no abnormal situation in the track between Sagoshi station and Kita-Amarume station as there was no extraordinary rolling of the vehicles. I did not remember the weather at that time. (4) The crews of the following train (i) The driver The following train departed from Sakata station at 19:11, behind the scheduled time of 19:00, as the concerned train had been operated behind schedule. The following train arrived at Higashi-Sakata station, 11 minutes behind schedule, and received the alarm signal of the train protection radio device at about 19:15, before the conductor closed the door for passengers. I heard the voices that the train dispatcher called the concerned driver repeatedly, but there was no response from the concerned driver. I thought that something might be happened, but I waited for the communication as I thought that it would interfere the communication if I used the train protection radio. The alarm signal of the train protection radio device had been sounding for over 30 minutes. I knew the occurrence of the accident by the simultaneous notification mail from the train dispatcher received by the business mobile phone of the conductor.

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It was little snow but severe lightings when the train departed from Sakata station. The vehicles rolled two times by the snowstorm while halting at Higashi-Sakata station. (ii) The conductor It snowed a little and wind was not particularly severe before the train departed from Sakata station. When the train arrived at Higashi-Sakata station, the snow fall became increased and the wind became harder compared as in Sakata station. When I was going to close the doors for passengers to depart form Higashi-Sakata station, I received the alarm signal of the train protection radio device. After that, I heard the voice of the train dispatcher calling the concerned driver for a while from the train radio device. (5) The crews of the opposite 831D train (i) The driver The opposite 831D train arrived at Amarume station on schedule at 19:14, and received the alarm signal of the train protection radio device, while halting in the station. As I communicated the train dispatcher using the train radio device but there was no response. While, I had been waiting, there was the communication from the train dispatcher to suspend the train operation. It was not windy when the opposite 831D train arrived at Amarume station, but the terrible gust of wind blew before and after received the alarm signal of the train protection radio device. As I did not know the direction of the gust of wind, the vehicles were rolling. In addition, it was thundering in the direction to Sakata district. (ii) The conductor I recognized that the wind was strong as the vehicles rolled by the wind, but it was not in the level as dangerous due to the strong wind, when the train arrived at Amarume station. It was dark sky with lightnings in the direction of the accident site, I felt that it was in rough weather. I received the alarm signal of the train protection radio device before departed from Amarume station. Usually, the alarm signal stops to sound within 3 to 5 minutes and the train dispatcher informed the communication, but the alarm signal continued sounding and there was no communication from the train dispatcher, on the accident day. Then, I used the business mobile phone to communicate with the train dispatcher and the Transport Section, that I was belonged, and noticed the occurrence of the accident. Here, the accident occurred as about 19:14.

2.2. Information on the Human Damages 2.2.1. Summary of the Human Damages The number of the casualties in the accident were as shown in Table 1. Among the total 46 passengers etc., hereinafter "the passengers etc." includes the staff for on-train sales, 5 persons were dead, and 33 persons were injured.

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Table 1. Casualties in the accident Passengers etc. Train crews Total Dead 5 0 5 Injured 32 1 33 Severely injured 28 0 28 Slightly injured 4 1 5 Total 37 1 38

2.2.2. Number of Casualties in each Vehicle The number of casualties in each vehicle were as shown in Table 2. There were 44 passengers etc. onboard the concerned train, and 5 persons were dead, and 32 persons were injured. Among the 44 persons, 35 persons were boarded on the 1st to the 3rd vehicles, the 5 dead persons and the 29 injured persons were in this group. Here, all 5 dead persons were boarded on the 1st vehicle.

Table 2. Number of casualties in each vehicle * Crews were excluded. Passengers etc. Dead Injured Casualties Total Male Female Total Male Female Total Male Female 1st Vehicle 16 9 7 5 2 3 11 7 4 16 2nd vehicle 14 14 0 0 0 0 14 14 0 14 3rd vehicle 5 3 2 0 0 0 4 2 2 4 4th vehicle 2 2 0 0 0 0 1 1 0 1 5th vehicle 2 0 2 0 0 0 0 0 0 0 6th vehicle 5 3 2 0 0 0 2 0 2 2 Total 44 31 13 5 2 3 32 24 8 37 Notes : The concerned train had been operated as the 1st to 3rd vehicles were the non-reserved seats, the 4th to the 6th vehicles were the reserved seats, usually. But on the accident day, as it was the winter crowded season, the concerned train was operated as the 1st and 2nd vehicles were the non-reserved seats and the 3rd to 6th vehicles were the reserved seat.

2.2.3. Seated Positions of the Passengers etc. The seated positions of the passengers etc., identified by the information obtained from the questionnaires and the hearing statements for the injured persons, and the information provided from the Police Headquarters of Yamagata Prefecture, hereinafter referred to as "the police information", were indicated in Attached Figure 4.

2.2.4. Status of the Dead Persons The distinction of sex and the cause of death of the dead persons, based on the police information, were shown in Table 3.

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Table 3. Causes of passenger's death Sex Causes of death Male Crushed, head and chest were pressed Male Crushed chest and abdomen were pressed Female Crushed, head and chest were pressed Female Brain contusion Female Shock by an external injury due to bruised whole body

Here, among 5 dead persons, 4 persons were found in around the center of the cabin of the 1st vehicle and the other 1 person was found beneath the vehicle in around the center of the 1st vehicle, and all 5 persons were confirmed as dead at the accident site.

2.2.5. Status of the Injured Persons (1) Summary of the questionnaire for the injured persons The investigation by the questionnaire were implemented for the 32 injured passengers etc., as to reply in the investigation sheet on the kinds of the injuries and the process and status when injured. As the results, numbers of the respondents for the questionnaire were, 12 males in total 24 males, i.e. response rate was 50 %, and 6 females in total 8 females, i.e., response rate was 65 %, and 18 persons in total 32 injured passengers etc., i.e., response rate was 56 %. (2) Boarded status before and after the accident The boarded status of the 18 passengers etc., who responded the questionnaire for the injured persons described in (1), hereinafter referred as "the responding injured persons", were as that the 17 persons were seated, and 1 passenger was standing. The boarded status when the concerned train stopped were indicated in Table 4. Among the 18 responding injured persons, 5 persons answered that their positions seated before and after the accident were the same, another 13 persons answered that their positions before and after the accident were different or the position when the train stopped was unknown. Here, one person who was standing at the occurrence of the accident answered that he was standing at the same position before and after the accident.

Table 4. Boarded status when the train stopped In the same position as In the different position from Position when the train stopped

before the accident [Person] before the accident [Person] was unknown [Person] 1st vehicle 1 4 2 2bd vehicle 1 2 3 3rd vehicle 1* 1 1 4th vehicle 0 0 0 5th vehicle 0 0 0 6th vehicle 2 0 0 Total 5 7 6 * Passenger who was standing.

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(3) The responses and the injured status of the passengers etc., in the accident The injured status of the 18 responding injured persons were as shown in Attached Figures 5-I and 5-II. Among 17 persons sitting in the seats, one in the 4 persons who answered as being seated in the same position as in before the accident, was injured by broken bones, however 5 in the 7 persons who answered as their positions had moved in before and after the accident, were injured by broken bones. Here, among 17 persons who were sitting in their seats, 7 persons answered that they held the seats and the armrests or stooped down to protect their heads. Among these 7 persons, 3 persons answered that their measures were considered as effective to protect their bodies. In addition, one standing person had been holding the handrail and answered that this measure would be effective to protect his body.

2.2.6. Moved Status of the Passengers etc., by the Impact of the Accident The status of movement of the passengers etc., due to the impact of the accident, based on the information obtained from the questionnaire for the injured persons and the statements of the injured persons described in 2.2.5 (1), were indicated in Attached Figure 6. Here, as the precise routes of the movements accompanied with the derailment could not be comprehended, the positions of the passengers etc. when the concerned train stopped and before the occurrence of the accident, were indicated. The status of the movement of the passengers etc., in each vehicle were as follows. (1) As for the 1st vehicle, 3 passengers boarded on the front part from the center of the vehicle moved to around the front edge of the cabin, and one passenger boarded on left side of the rearmost of the vehicle moved little. (2) As for the 2nd vehicle, 2 passengers boarded on right side of the vehicle moved to left side of the vehicle. (3) As for the 3rd vehicle, 1 passenger boarded on left side of the vehicle moved to right side of the vehicle, and the 1 passenger boarded on right side of the front deck moved little. (4) As for the 6th vehicle, the 2 passengers boarded on the rear part from the center of the vehicle, i.e., the first-class seats, moved little. Here, the information on the movement of the passengers could not be obtained for the 4th and 5th vehicles.

2.3. Information on the Physical Damages 2.3.1. Damaged status in the tracks and the railway structures [Refer to Attached Figures 7, 8, 9] In order to identify the damaged positions, the sleepers of the up track in around the accident site were numbered with symbols. The sleeper closest to the rear edge in the direction to Akita station, hereinafter referred to as "the over-road bridge start edge", of the Enoki over-road bridge, herein after referred to as "the over-road bridge", was named as the sleeper No.1, located at around 158,150 m from the origin at Niitsu station, hereinafter "from the origin at

18 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Niitsu station" was omitted, and the sleepers were numbered in turns in the direction of the destination of the concerned train. On the other hand, the sleeper next to the sleeper No.1 in backward, at around 158,151 m, was numbered with the symbol as the sleeper No.1b, and the sleepers in backward from the over-road bridge start edge were numbered in turn. There were many traces considered as caused by the wheels etc., in the sleepers, left and right rails, ballast and slope of the embankment in forward direction from the sleeper No.16b. Here, there was no traces in the backward track from the sleeper No.16b. The status of the traces was described for the section in the backward track, i.e., toward Akita station, from the over-road bridge start edge, the section on the over-road bridge and the section in forward track, i.e., toward Niitsu station, from the end edge of the over-road bridge, hereinafter referred to as "the over-road bridge end edge", in the followings. (1) The backward section, i.e., toward Akita station, from the over-road bridge start edge (i) There were traces considered as caused by the running wheels on the sleepers and the rail fastening devices in left rail side of the inside gauge on the sleepers No.12b to No.8b, and the surfaces of these sleepers were lacked and damaged. The rail fastening devices were not fallen away but they were in the crushed status as the spring clips were broken and the heads of the fastening bolts were deformed. (ii) There were traces considered as caused by the running wheels on the rail fastening devices in left rail side of the inside and outside gauge on the sleepers No.7b to No.1b, and the surfaces of these sleepers were lacked and damaged. The spring clips of all rail fastening devices in the inside gauge of this area were cut and damaged, and the rail fastening devices in outside gauge were fallen away except for the sleeper No.7. (iii) There were flaws on the rail surface from around the center of top surface of rail to the gauge corner on the sleepers No.16b to No.15b. There were many flaws almost parallel to the direction of the train running, on the top surface of left rail in forward direction from the sleepers No.12b. (iv) There were plural traces on all sleepers between the sleepers No.12b to No.1b. (v) There was no trace in right rail and its surroundings. (2) The section on the over-road bridge (i) All sleepers from the sleepers No.1 to No.21 were composed of the wooden sleeper for the bridge. There were the traces considered as caused by the running wheels in the outside gauge of left rail, on all sleepers in this area. (ii) In all sleepers, there were the fallen off, the folded and damaged and deformation of the fastening bolts and the anti-rail tilting metal*4, the deformation of the tie plates in the rail fastening devices in the inside and outside gauge of left rail. These damages in the rail fastening devices were existed in inside gauge from the sleeper No.1 to the sleeper No.19, and in outside gauge from the sleeper No.1 to the sleeper No.13 and from the sleeper No,19 to sleeper No.21. (iii) There were many deformations, fallen off and came out of the left hook bolts*5 in all sleepers.

19 Translated by T. A. Lab., Inc., Japan, Sept., 2019

(iv) There were many flaws parallel to the direction of train running or the flaws continued to outside gauge of left rail, on the top surface of left rail in the entire section. (v) There was the lack and damages only in the front part of the sleeper No.1, and the sleeper No.2 was folded and damaged in the outside gauge of left rail. There were the remarkable damages such as cracks etc., in the sleepers No.3 and No.4. (vi) A part of sleepers were pushed to forward, particularly the sleepers No.2 to No.5, No.12, No.17, and No.18 were moved significantly. (vii) There were the flaws as scraped on the gauge corners of left rail from the sleepers No.13 to No.15 discretely. (viii) The L-shaped sleeper connectors*6 in left side of sleepers from the sleepers No.1 to No.10 were deformed. The L-shaped sleeper connectors in the sleepers No.11 to No.21 came off and fell off in around 158,130 m. (ix) There was no trace considered as caused by the running wheels on the concrete blocks installed in upper left of the abutment at the over-road bridge start edge, and the iron footboards for the passage installed in upper left of the over-road bridge, hereinafter referred to as "the grating". On the other hands, there were plural traces considered as caused by the running wheels on the concrete blocks installed in upper left of the abutment at the over-road bridge end edge. (x) There was no trace on the right rail and its surroundings. (3) The forward section, i.e., toward Niitsu station, from the over-road bridge end edge The traces in the area to the position where the rear end of the concerned train had stopped, in around the sleeper No.132, were as follows. (i) The sleepers were lacked or folded and damaged in the outside gauge of left rail in all sleepers to the sleeper No.71, and the sleepers No.75 to No.93, No.102 to No.127, No.129 and No.130, in the inside gauge of a part of the sleepers from the sleeper No.35 to No.130, and in the outside gauge of the sleepers No.117 and No.124. The damages of the sleepers in the inside gauge of right rail were existed discretely in the sleepers in the forward direction from the sleeper No.72. There were severe damages in the outside gauge of left rail between the sleepers No.31 to No.43, No.52 to No.70, No.79 to No.89 and No.115 to No.117. (ii)There were the traces considered as caused by the running wheels discretely, on the rail fastening devices in inside and outside gauge of left rail in the sleepers in forward direction from the sleeper No.35. Among these sleepers, sleepers were deformed, fallen off, and the fastening bolts were folded and damaged or came off in outside gauge in a part of the sleepers to the sleeper No.61, from the sleepers No.115 to No.122 and No.131. Also, the rail fastening bolts and the spring clips were damaged as deformed or fallen off in the inside gauge of the sleepers No.63, No.71, No.72, No.76 to No.86 and No.101 to No.108. In addition, there were damages as the deformation of the rail fastening devices in the outside gauge of right rail on the sleepers No.100, No.107 to No.109 and No.118. (iii) There were many flaws discretely on the top surface of left and right rail. The flaw on left rail had been started from the sleeper No.23, the flaw on right rail had been started from the

20 Translated by T. A. Lab., Inc., Japan, Sept., 2019

sleeper No.70. (iv) There were the flaws as scraped discretely, on the gauge corner of left rail from the sleeper No.23 to the sleeper No.29 and from the sleeper No.69 to the sleeper No.76. (v) The track panels*7 had been deformed to left in the section from forward of the over-road bridge to the position where the concerned train had stopped. (vi) The left shoulder portion of the ballast was collapsed to forward direction continuously, and the left edge surfaces and side surfaces of many sleepers were exposed into air, in the section forward from the sleeper No.24. (vii) The left slope of the embankment in the forward section from around the sleeper No.55 was collapsed continuously toward the compost house, which was the steel frame one-story shed for agricultural use built in left side of the track in around 158,050 m. Here, refer to 2.3.4.1 on the compost house. The sleepers and the rail fastening devices were damaged discretely to around 158,025 m in the forward section from the position where the rear end of the concerned train had stopped. Among these, the damages in inside and outside gauge of left rail were particularly severe as the sleepers were significantly lacked and broken between 158,055 m and 158,030 m. The sleepers were lacked and damaged, the fastening bolts were folded and damaged or came off, the spring clips were broken and damaged, in inside and outside gauge of right rail from 158,059 m to 158,041 m and around 158,029 m. *4 "Anti-rail tilting metal" is a part of the rail fastening device, i.e., the metal to suppress the amount of the tilting and the twisting of rail, when the rail had moved, tilted and twisted due to the lateral force caused by the wheel load and the large lateral force of the vehicle acted to the rail. *5 "Hook bolt" is the bolt used to fix the sleepers for the bridge to the bridge girder. *6 "L-shaped sleeper connector" is the L-shaped steel plate to be attached to prevent displacement of the sleepers on the bridge girder. *7 "Track panel is the ladder shaped structure composed of rails and sleepers using the rail fastening devices

2.3.2. Damaged Status etc., of the Electric Power Related Facilities [Refer to Attached Figures 7, 8, 10] The damaged status of the overhead contact line related facilities such as the poles etc., and the sorts of cables in around the accident site were as follows. All damaged electric power related facilities had been installed in left side of the railway track. Here, the poles were numbered as follows. The pole in around 158,360 m was named as No.I. The pole in around 158,313 m was named as No.II. The pole in around 158,263 m was named as No.III. The pole in around 158,213 m was named as No.IV. The pole in around 158,163 m was named as No.V. The pole in around 158,113 m was named as No.VI. The pole in around 158,110 m was named as No.VII.

21 Translated by T. A. Lab., Inc., Japan, Sept., 2019

The pole in around 158,066 m was named as No.VIII. The pole in around 158,063 m was named as No.IX. The pole in around 158,013 m was named as No.X. The pole in around 157,963 m was named as No.XI. (1) Pole tilted to left, the attached column*8 deformed, the weights*9 of the pulley type automatic tensioner*10 collided with upper part of the steady device, in the pole No.V. (2) The poles were folded and damaged in four poles, i.e., the pole No.VI to No.IX. The folded directions and the distance from the track center of the up track of each folded and damaged poles were as follows. The pole No.VI folded to left in a little forward, 3.75 m distant from the track center. The pole No.VII folded to left in a little forward, 3.65 m distant from the track center. The pole No.VIII folded forward in a little left, 3.92 m distant from the track center. The pole No.IX folded forward in a little left, 3.92 m distant from the track center. (3) The supporting arm for the feeder was deformed in one pole, i.e., the pole No.IV. (4) The hinged cantilevers*11 fell away and hung down and the long rod insulators were broken and damaged in six poles, i.e., the pole No.V to No.X. (5) The pull-off arm was deformed in one pole, i.e., the pole No.IV. (6) The suspension insulators for the feeder were broken and damaged in four poles, i.e., the pole No.I to No.III, and No.XI. (7) The hangers were deformed in the section from the pole No.IV to around 157,963 m. (8) The overhead contact line hung down in the section from pole No.IV to around 157,963 m. (9) The connector wire was broken in one pole, i.e., the pole No.VIII. (10) The feeder and the protective wire*12 were broken in the section from the pole No.V to around 158,013 m. (11) The trough and the communication cables and the signal cables in the trough were damaged as deformed and crushed in the section between around 158,115 m and 158,070 m. *8 "Attached column" is the steel material attached to the pole in order to attach the metals etc., in the upper part of the pole. *9 "Weight" is the device to pull the overhead contact line by the gravitational force of the weight, a part of the pulley type automatic tensioner. *10 "Pulley type automatic tensioner" is the device to maintain the tension of the overhead contact line constant by applying the principle of the pulley. *11 "Hinged cantilever" is the cantilever installed in the poles to suspend the overhead contact line in overhead, and mounted in the structure as to rotate horizontally around the supported point in order to respond the movement of the overhead contact line due to the temperature change, particularly. *12 "Protective wire" is the overhead electric wire to prevent the flashover, which is the discharge due to the electric breakdown generated on the surface of the insulation material such as the insulator in the part n the different electric potential or the polarity.

2.3.3. Damaged Status of the Vehicles All vehicles in the concerned train had been derailed. Among them, the 1st to the 3rd vehicles had been fallen off from the embankment and overturned. The damaged status of each vehicle

22 Translated by T. A. Lab., Inc., Japan, Sept., 2019 was as follows. 2.3.3.1. The 1st vehicle, Ku Ha 481-3506 [Refer to Attached Figure 11-I] The whole vehicle body had fallen off to left of the embankment and fell on its left surface down and its roof toward the compost house, and around the center of the roof had been folded in right angular due to be collided with the north-west corner of the compost house, the rear part of the vehicle was sandwiched between the compost house and the 2nd vehicle. The statuses of the major damages were as follows. (1) The roof collided with the compost house was crushed into the cabin from center to rear portions and severely damaged. (2) The front left portion of the driving cab had been deformed as being dented toward cabin. (3) There were the fretting traces slanted from side surface of the driving cab to under floors in the front part of right surface of the vehicle body. In addition, the lid to take out devices of the device box mounted under the driving cab had been dropped and lost. (4) There were the hit traces and deformations in the entire rear surface of the vehicle, particularly, the right lower portion had been bent significantly toward the roof and the outside plate had damaged as dent toward the cabin. (5) The space of the cabin had been reduced remarkably due to the roof crushed toward the cabin and the seats were extremely damaged in the portion where the vehicle body had folded in right angular. The damages in the cabin were relatively slight in the forward portion from there, although the vehicle body had been distorted. (6) The front and the rear bogies had been come off from the vehicle body. The front bogie had been fallen into the space between the vehicle body center of the 1st vehicle and the rear vehicle body of the 2nd vehicle, and the rear bogie had been fallen in around the rear part of the vehicle body roof of the 2nd vehicle. As for the front bogie, right side beam of the bogie frame was damaged, the axle spring in right side of the 2nd axle had been fallen away and the axle damper was broken and damaged. In addition, the brake disk in right side of the 2nd axle was broken and damaged. As for the rear bogie, there were the fretting traces in the front part of the side beam in left side of the bogie frame. The axle damper in left was broken and damaged, and the axle damper in right was fallen away, in the 1st axle. In addition, the bogie bolster and the bolster anchor were deformed. Here, there was no remarkable trace in the wheels in the both front and rear bogies. (7) The coupler between the 1st and the 2nd vehicles and the buffers had been fallen away from both vehicles and fell in around the rear portion of the 1st vehicle.

2.3.3.2. The 2nd vehicle, Mo Ha 485-3018 [Refer to Attached 11-II] The whole vehicle tumbled down to left of the embankment and fell on its left side down as its floor faced to the compost house. The front portion of the left surface was in the bottom of the embankment and the rear portion of the left surface leaned on the embankment, then, the center of the left side surface was staying in the air. The statuses of the major damages were as follows.

23 Translated by T. A. Lab., Inc., Japan, Sept., 2019

(1) The right side of the vehicle body deformed in a bow shape toward the roof, bent and damaged toward the cabin from under window part to the underframe*13, and all window glasses were broken and damaged. (2) The left side of the vehicle body deformed as under window part in the vehicle center projected to outside significantly and the rear underframe severely damaged as to bend to upward, and all window glasses were broken and damaged. (3) As for the front surface of the vehicle body, there were the collided traces in lower part, the low left and the low right parts were bent toward the cabin and damaged. (4) As for the rear surface of the vehicle body, there were the collided traces in lower part, the lower right part was bent toward the cabin and damaged. (5) As for the cabin, there were deformations in the floor, the side wall and the ceiling, but there was no deformation as to damage the seats significantly, the space in the cabin was in the state as relatively secured. (6) The front and the rear bogies had been come off from the vehicle body and fell into the space between the center of the 1st vehicle and the rear part of the 2nd vehicle. As for the front bogie, right side beam of the bogie frame was damaged, the right axle spring of the 2nd axle had been fallen away and the axle damper had broken and damaged. As for the rear bogie, there were the fretting traces in right side beam of the bogie frame. In addition, there were plural hit traces in the circumference of the corner of the tread and the outer surface of left wheels, hereinafter referred to as "the tread corner part", in all four axles of the front and the rear bogies. The hit traces in the tread corner part in the rear bogie were relatively large compared to that in the front bogie. (7) The coupler between the 2nd and the 3rd vehicles had been fallen away from both vehicles accompanied with the buffers and fell on between front parts of the 1st and the 3rd vehicle. *13 "Underframe" is the framework composed of the beam materials in the components of a vehicle body, used to attach the basement of the structures above floor and the underfloor equipments.

2.3.3.3. The 3rd vehicle, Mo Ha 484-3018 [Refer to Attached Figure 11-III] The whole vehicle had been fallen to left of the embankment and had been overturned as its right side down and rotated about 180 degrees from the direction of train running. The rear part of the vehicle had been contacted with the front part of the 4th vehicle. The statuses of the major damages were as follows. (1) There were the hit traces in the entire front surface of the vehicle and the outside plate was distorted. Particularly, the center part of the left outside plate was bent toward the cabin and damaged and there were the collided traces in the edge and the lower part of the right side of the vehicle body. (2) There were the hit traces and the fretting traces from under window part to the underframe in the front part of right side surface of the vehicle body. (3) Three window glasses in left side of the vehicle body were broken and damaged. (4) There were the collided traces from under window part in the rear end of left side surface

24 Translated by T. A. Lab., Inc., Japan, Sept., 2019

of the vehicle body to the underframe and bent toward the cabin and damaged. (5) The pantograph equipped on the roof was broken and damaged. (6) There was little damage in the cabin. (7) The front bogie had been come off from the vehicle body and fell to around the front part of the 1st vehicle body. The rear bogie had been come off from the vehicle body and remained on the track and had been sandwiched by the underfloor equipment in the center of the 4th vehicle. As for the front bogie, right side beam of the bogie frame was damaged, and the axle damper had broken and damaged. As for the rear bogie, the bogie bolster was displaced in the upper direction from the bogie frame. There were the fretting traces in the flange of right wheel of the 1st axle in the front bogie, and the hit traces in the tread corner part of left wheel of the 2nd axle in the rear bogie.

2.3.3.4. The 4th vehicle, Mo Ha 485-3044 [Refer to Attached Figure 11-IV] The front part of the vehicle body had run out to left of the embankment and contacted with the rear part of the 3rd vehicle, the rear part of the vehicle body had been contacted with the front part of the 5th vehicle on the down track. The center part of the vehicle body had been laid on the rear bogie of the 3rd vehicle and the front bogie of the 4th vehicle which had been come off from each vehicle body and were staying on the track. The statuses of the major damages were as follows. (1) The left center part of the front surface of the vehicle body was bent toward the cabin and damaged, and there were the collided traces in around left lower part of the front surface of the vehicle body. (2) There were the collided traces in the left upper part, and the hit traces in the right upper part of the rear surface of the vehicle body. (3) The front and the rear bogies had come off from the vehicle body but had been staying on the track. The front bogie had been sandwiched by the underfloor devices in the center of the vehicle body of the 4th vehicle and the1st and the 2nd axles derailed to right and left, respectively. The lower center pivot*14 of the front bogie was damaged and there were the hit traces in around lower part of the left axle spring of the 1st axle in the rear bogie. In addition, there were plural hit traces in the circumference of the tread corner part of the left wheel of the 1st axle in the front bogie. *14 "Center pivot" is the part to combine the bogie to the vehicle body. In the 485 series vehicles, the center pivot was composed of the upper center pivot, the convex shaped to downward, in the vehicle body and the lower center pivot, the concave shaped to upward, in the bogie, and becomes to the center of rotation of the bogie.

2.3.3.5. The 5th vehicle, Mo Ha 484-3044 [Refer to Attached Figure 11-V] The front part of the vehicle body went off to the down track significantly, contacted with the rear part of the 4th vehicle, and had been stayed in the air above the down track. The statuses of the major damages were as follows. (1) Two window glasses in right side of the vehicle body were broken and damaged. The

25 Translated by T. A. Lab., Inc., Japan, Sept., 2019

pieces of the broken glass of the front window were scattered into the cabin. (2) There were the hit traces in the upper part of the front surface of the vehicle body. (3) The pantograph etc., on the roof were broken and damaged. (4) The front and the rear bogies had been come off from the vehicle body. The 1st axle in the front bogie had derailed to right and all two axles in the rear bogie had derailed to right. Here, the front and the rear bogies had been staying on the track, and the 2nd axle in the front bogie was not derailed.

2.3.3.6. The 6th vehicle, Ku Ro Ha 481-3010 [Refer to Attached Figure 11-V] There was little damage in the 6th vehicle. The 6th vehicle had been halted in the status as only the right wheel of the 1st axle in the front bogie had derailed to inside gauge, as contacted with the rear part of the 5th vehicle.

2.3.4. Damaged Status etc., of the Objects Except for the Railway Facilities and the Vehicles The compost house had been demolished completely due to being collided by the concerned train. The structures and the damaged status of the compost house were as follows. 2.3.4.1. The structure etc., of the compost house [Refer to Attached Figure 12] The compost house was in about 11 m left from the center of the up track. The compost house was composed of the reinforced concrete foundation and the steel frame building, the dimensions were about 40 m in north-south direction, about 12.5 m in east-west direction.

2.3.4.2. Damaged status of the compost house [Refer to Attached Figure 12] As for the center part of western side of the compost house, the steel frames were bent toward inside and almost all steel frames were broken and cut, the roof and the upper part of the outer wall were fallen away and scattered to inside of the compost house. In addition, a part of the concrete wall in the lower part of the outer wall were broken and damaged as to expose the steel reinforcing rods. As for the northern side of the compost house, the north west corner part of the building was collapsed by the rear roof of the vehicle body of the overturned 1st vehicle, the steel frames were bent toward inside building and the entire side wall had leant to west, and a part of the roof and the upper part of the outer wall had fallen away. In addition, a part of the concrete wall in the lower part of the outer wall were broken and damaged as to expose the steel reinforcing rods.

2.4. Information on the Train Crews The concerned driver was 29 years old male, having the class-A driver's license of the electric motor car issued on September 19, 2001. The concerned conductor was 26 years old male.

2.4.1. Information on the Concerned Driver

26 Translated by T. A. Lab., Inc., Japan, Sept., 2019

(1) The medical checkup According to the records of the Company, the concerned driver had been taken the medical aptitude test etc., prescribed in the Company's rules, six times from July 2003 to the occurrence of the accident, and there was no abnormal situation particularly in the results. (2) The driving aptitude test According to the records of the Company, the concerned driver had been taken the driving aptitude test prescribed in the Company's rules, three times from May 2000 to the occurrence of the accident, and there was no abnormal situation particularly in the results.

2.4.2. Information on the Concerned Conductor (1) The medical checkup According to the records of the Company, the concerned conductor had been taken medical aptitude test etc., prescribed in the Company's rules, six times from July 2003 to the occurrence of the accident, and there was no abnormal situation particularly in the results. (2) The driving aptitude test According to the records in the Company, the concerned conductor had been taken driving aptitude test prescribed in the Company's rules, three times from May 2001 to the occurrence of the accident, and there was no abnormal situation particularly in the results.

2.5. Information on the Railway Facilities etc. 2.5.1. Outline of the Railway Facilities (1) The railway track The track in around the accident site was the double track and the gauge was 1,067 mm. The concerned bridge, extended for about 626 m and the center was at 158,651 m, existed in the section in the direction of Akita station from 158,339 m, and the over-road bridge existed in the section between 158,150 m and 158,139 m. The concerned bridges and the over-road bridges were built for up and down track, respectively. The structure of the concerned bridge was the 4-stranded steel girders, and the 9-stranded trussed girder. The structure of the over-road bridge was the 1-stranded steel girder. The concrete blocks, which were 1.8 m long, 0.5 m wide and 0.17 m high, were installed in left and right of the sleepers on the abutment located on both edges of the over-road bridge. The track between the concerned bridge and the over-road bridge and the track in forward section from the over-road bridge were constructed on the embankment, the rice field were mainly spread in both sides of the embankment. The embankments were constructed for each up track and down track individually until to around 158,060 m, and the up and down tracks were constructed on the same embankment in the forward section from that point. The track shape of the up track between the concerned bridge and the position where the concerned train stopped was straight. The grade of the up track was flat in the section to 158,320 m from the direction to Akita station, and 8.2 ‰ upgrade between 158,320 m and 157,951 m.

27 Translated by T. A. Lab., Inc., Japan, Sept., 2019

The height of the embankment and the width of the left slope, where the 1st vehicle to the 3rd vehicle were fallen away, were 4.0 m high and 5.6 m wide in around 158,160 m, 3.6 m high and 5.3 m wide in around 158,070 m, and 3.2 m high and 6.0 m wide in around 158,000 m, respectively. (2) The track The 50 kgN rails were used in the track. The continuous welded rails were constructed in the section except for the concerned bridge, the expansion joints were laid in around 158,297 m to 158, 290 m. In addition, the guard rails were installed in the section from 158,970 m to 158,350 m on the concerned bridge. The wooden sleepers were laid in the concerned bridge and the over-road bridge. the installation ratio of the wooden sleepers were 46 sleepers per 25 m in the concerned bridge, and 21 sleepers per 11 m in the over-road bridge. The prestressed concrete sleepers were installed in the sections from 158,339 m to 158,150 m and in the forward section from 158,139 m, the installation ratio was 38 sleepers per 25 m. The rail fastening devices for wooden sleepers were installed in the sections of the concerned bridge and the over-road bridge, and the rail fastening devices for prestressed concrete sleepers were installed in the section except for the above wooden sleeper section. There was no ballast in the sections of the concerned bridge and the over-road bridge, and the other sections were constructed by the ballast using the crashed stones of the 250 mm thick.

2.5.2. Outline of the Electric Power Facilities etc., in Around the Accident Site The high voltage distribution lines of the 6.6 kV three phase alternating voltage, the feeder wires and the overhead contact lines of the single phase alternating voltage 20 kV, were installed in around the accident site, and transmitted and fed electric power from Sakata Substation. The concrete poles were planted in every about 50 m in the section in the direction to Niitsu station from 158,213 m in the up track. Here, there was the air joint*15 in around 158,163 m to 158,013 m. Therefore, the pulley type automatic tensioner were equipped to the poles No.V and No.X. The overhead contact lines were suspended by the hinged cantilevers. The communication cables and the signal cables were laid in the trough constructed in left side along the track. Here, the automatic block system was applied as the block system. *15 "Air joint" is the joint to connect the forward and the backward overhead contact lines electrically in the connecting point of the overhead contact lines where the backward and forward overhead contact lines were laid doubly in parallel.

2.5.3. Information Memories in the Level Crossing Protection Device [Refer to Attached Figure 13] The information memories were equipped in the level crossing protection devices in Barano level crossing, Minami-Hirata level crossing, Nakadai level crossing and Hiraoka level crossing. The indication etc., of the history of the operation etc., were possible by connecting the readout device.

28 Translated by T. A. Lab., Inc., Japan, Sept., 2019

In these information memories in the level crossing protection devices, the operating status of the major relays, i.e., the connected or disconnected status of the contact point of the relay, were sampled every 1/64 seconds, and record the time of on or off of the contact point as effective when the continuing 4 sampled data showed the same value. There were the operation records in the information memories when the concerned train had been running from Sakata station toward the accident site, but the record for the exit point of Minami-Hirata level crossing were not existed. The passing time from entrance of the frontmost wheel axle to the exit of the rearmost wheel axle of the concerned train against the electronic train detector*16, based on the records of the operating history, and the passing velocity of the concerned train calculated by correcting the above passing time etc., were as shown in Table 5.

Table 5. The passing time of the electronic train detector and calculated passing velocity Name of the electronic train detector Kilometerage Passing time Passing velocity Entry of Barano level crossing 162,225 m About 4.8 s About 105 km/h Entry of Minami-Hirata level crossing 161,245 m About 5.7 s About 89 km/h Exit of Barano Level crossing 161,111 m About 5.9 s About 85 km/h Entry of Nakadai level crossing 160,607 m About 5.8 s About 93 km/h Exit of Nakadai level crossing 159,379 m About 5.7 s About 90 km/h Entry of Hiraoka level crossing 159,008 m About 4.9 s About 106 km/h

In addition, the passing time, from the entry of the frontmost wheel axle of the concerned train to the start point of each level crossing to the exit of the rearmost axle of the concerned train from the end point of each level crossing, based on the records of the operating history, and the average passing velocities calculated from these passing times were as shown in Table 6.

Table 6. Passing time of level crossing control section and calculated average passing velocity Level crossing Passing time Average passing velocity Barano level crossing About 43.6 s About 103 km/h Nakadai level crossing About 51.6 s About 96 km/h

*16 "Electronic train detector" is the special track circuit used to detect the train approached or passed the level crossing. There were 2 kinds of the electronic train detectors categorized by the detecting methods, i.e., the electronic train detector using closed track circuit is used for the start point for warning, and the electronic train detector using open track circuit is used for the stop point for warning.

2.5.4. Train Protection Radio Device The train protection radio device is the radio device used for the arrangement of the urgent train stop, by pushing the button to send the alarm signal to the trains existing in the circular area of about 1 km in radius from the train protection radio device as its center, and the train

29 Translated by T. A. Lab., Inc., Japan, Sept., 2019

protection radio device in the train that received the alarm signal indicates the stop signal based on the alarm signal in the driving cab. Here, the stop signal was not indicated if the train protection radio device had been troubled. The train protection radio devices were equipped in all vehicles having the driving desk and operated in the conventional lines of the Company, hereinafter the section between Echigo-Yuzawa station and Gala-Yuzawa station of Joetsu Line was not included in "the conventional line". Usually, if the power source for the train protection radio device had failed, the circuit was switched to the spare power source automatically. Here, as the device notifying the train dispatcher automatically the indication of the stop signal due to the alarm signal of the train protection radio was not equipped in the dispatcher's room of Niigata Branch Office, the train dispatcher did not know the indication of the alarm signal until to be notified from the crews of the train that operated the the train protection radio to send the alarm signal or the crews of the train that received the alarm signal, using the train radio device or the business mobile phone. According to the records of the accident day, there was the record of the operation of the alarm signal on 19:33, December 25 in the train protection radio device in the 6th vehicle of the concerned train. Here, the time in the train protection radio device was in the state about 18 minutes fast.

2.5.5. Train Radio Device The train radio device is the device to realize the telephone call directly by the radio between the on-train device and the ground facilities, and used for the communication between train crews and the train dispatchers etc. The device used in Uetsu Line was the simplex type to communicate alternatively by pushing the talk button. The communications between the train crews and the train dispatchers using the train radio were recorded and filed as the sound data in the long time recording device equipped in the dispatcher's room of Niigata Branch Office. According to the records on the accident day, there was no communication record between the train dispatcher and the concerned driver or the concerned conductor after the occurrence of the accident, and there was only the sound date file that the train dispatcher called the concerned driver.

2.5.6. Anemometer An anemometer, hereinafter referred to as "the existing anemometer", had been installed in between the up and the down tracks on the embankment at the point around 159,000 m, about 800 m distant backward from the accident site, in the direction to Akita station from the concerned bridge. The existing anemometer was the wind cup type anemometer*17 located at the height of 5 m above the rail level, and could measure up to the wind speed of 60 m/s. The existing anemometer had been passed the examination of the Japan Meteorological Agency, JMA on May 23, 2002, then, the accident day was within the effective period of the examination, i.e., 5 years.

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*17 "Wind cup type anemometer" is one of the types of the anemometers, to layout 3 or 4 half sphere or conic cups, i.e., wind cup, in equal angle intervals at the tips of the horizontal arms attached to the rotating shaft supported vertically. When the wind blows, the wind cups rotate regardless of the wind direction and designed as the rotating speed is almost proportional to the wind speed.

2.5.7. The PreDAS [Refer to Attached Figure 14] The PreDAS is the abbreviation of the Prevention of Disaster Alarm System of the Company, to notify the necessity of the operation control or the inspection of the railway facilities, by directly sending the observed data of the water gauges, the seismographs, the rain gauges, the anemometers, etc., installed along the railway tracks, to the train dispatchers and the Track Maintenance Technology Center, etc. The system was composed of the terminal unit which input the observed data from the observing devices, the accumulating unit to collect the observed data from the terminal units, the central unit to collect the observed data of the accumulating unit, the display unit to indicate the messages and to sound alarms when the operation control had issued, etc., in addition to indicate the data transmitted from the central unit or the accumulating units. Here, as described in 2.8.3, the observed data by the existing anemometer in the nearest place to the accident site, were collected and recorded as the observing point at the concerned bridge. The display unit installed in the dispatcher's room in Niigata Branch Office had been set to implement the following functions. (1) The white indication that is the message on the monitoring formation for over 15 m/s wind speed in the earlier control section, refer to 2.7.2.4, and for over 20 m/s wind speed in the normal control section. (2) The yellow indication and sounding alarms that are the message on the speed control for over 20 m/s wind speed in the earlier control section, and for over 25 m/s wind speed in the normal control section. (3) The red indication and sounding alarms that are the message on the cancellation of operation for over 25 m/s wind speed in the earlier control section, and for over 30 m/s wind speed in the normal control section.

2.5.8. Status of the Inspection etc., of the Railway Structures and the Tracks The inspection of the railway structures and the railway tracks were prescribed in the "Implementing Standard for Civil Facilities" and the "Implementing Standard for Railway Facilities", a part of the implementing standard reported by the Company to the chief of the District Transport Agency, hereinafter referred to as the "Reported Implementing Standards", based on the "Ministerial Ordinance Providing for the Technological Standard for Railways". The inspections of the railway structures have been prescribed to implement every period not exceeded 2 year, and the inspections of the track irregularities have been prescribed to implement every period not exceeded 1 year, respectively. The latest inspections of the over-road bridge and the embankment before the occurrence of the accident were implemented on June 8, 2004, but there was no abnormal data in the inspected

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records. In addition, the track irregularities in around the accident site were measured on October 6, 2005, using the high speed track inspection car, but there was no track irregularity exceeded the track maintenance standard values*18 in the inspected records. There was no track irregularity exceeded the track maintenance standard value in the section from the place where the damages were found in the track to the direction to Akita station, in the track irregularities measured after the accident by the portable track inspection device, implemented on December 28, 2005. [Refer to Attached Figure 15] *18 "Track maintenance standard values" were prescribed by the railway operators, as it should be corrected promptly, within 15 days after found if the measured track irregularities exceed the standard values,, or to slow down operating velocity of the trains if the correction was difficult. The standard values for the dynamic track irregularities were applied to the track irregularities measured by the high speed track inspection car, and the standard values for the static track irregularities were applied to the track irregularities measured by the manual inspection or the portable track inspection device.

2.6. Information on the Vehicles 2.6.1. Outline of the Vehicles (1) Category of the vehicles AC-DC dual system electric railcar, AC 20 kV, DC 1.5 kV (2) Number of vehicles in trainset 6 vehicles (3) Symbol and number and the major specification As shown in Attached Figure 16 (4) Brake system Electromagnetic straight air brake equipment together with dynamic braking, accompanied with the snow-proof brake

2.6.2. Structure of the Bogies The structure of the bogie of the vehicles in the concerned train was to suspend the whole weight of the vehicle body by the disc shaped wearing plate mounted on around the lower center plate on the bogie bolster, where the upper center plate attached to the bottom of the vehicle body works to guide the rotating center of the bogie. Here, the vehicle body and the bogie were not connected as the upper center plate had not bored the bogie bolster of the bogie, and the calculated insertion lengths of the upper center plate into the lower center plate in the concerned train were about 65 mm to 86 mm based on the measured values in the important parts inspection implemented on December 7, 2004.

2.6.3. Remodeling of the Vehicles The latest remodeling works of the vehicle bodies, cabins and devices etc., of the vehicles in the concerned train were implemented on December 2000, to remodel the following matters mainly. (1) As for the vehicle bodies, shape change of the front surface of the vehicle, enlargement of the side windows and change of painting of the outer panel etc., were implemented. (2) As for the cabins, renewal of the floors and the inner panels, replacement of the seats, repairment of the lavatories and the washroom, etc. were implemented. (3) As for the devices etc., replacement of the auxiliary power unit, the air compressor and the

32 Translated by T. A. Lab., Inc., Japan, Sept., 2019

under floor wiring cables etc., were implemented. Here, according to the Company, the height of the gravity center of the vehicle body after remodeled did not estimated and the mass of the remodeled vehicle body were not measured, because the remodeling works did not significantly change the vehicle body structure and masses of the devices etc. Therefore, the height of the gravity center of the vehicle bodies were measured for the 2 vehicles each for the Ku-Ha 481-3300 series vehicle and the Mo Ha 485-3000 series vehicle which had been implemented the same remodeling works as the concerned train, the average height of the gravity center of the vehicle bodies were 1.673 m and 1.6655 m from the rail level*19, respectively, and the average masses of the vehicle bodies were 30,445 kg and 26,290 kg, respectively. In addition, according to the Company, the masses of the vehicle bodies had decreased about 1.2 ton and about 1 ton in the 1st vehicle and the 2nd vehicle, respectively, after the remodeling works had implemented for the vehicles of the concerned train. *19 "Rail level" is the plane connecting the top surfaces of right and left rails, and sometimes indicated as "RL".

2.6.4. Inspection of the Vehicles The latest inspection of the 1st to the 6th vehicles of the concerned train before the accident were implemented as shown in Table 7. There was no abnormal situation in the records of the inspection.

Table 7. The latest inspections implemented before the accident Category of Inspection period. Implemented date inspection Every period not The 1st The 2nd and The 4th and The 6th exceeded the vehicle the 3rd the 5th vehicles following period or vehicles vehicles running distance. General 8 years Dec. 19, 1998 Dec. 24, 2002 Dec. 21, 2000 Dec. 19, 1998 inspection Important parts 4 years or 400,000 Dec. 7, 2004 Dec. 7, 2004 Dec. 7, 2004 Dec. 7, 2004 inspection km running distance Regular 90 days Nov. 24, 2005 Nov. 24, 2005 Nov. 25, 2005 Nov. 25, 2005 inspection Daily inspection 6 days Dec. 22, 2005 Dec. 22, 2005 Dec. 22, 2005 Dec. 22, 2005

2.7. Information on the Handling Train Operation 2.7.1. The Limited Speed 2.7.1.1. Outline of the limited speed The limited speeds of the concerned train in Uetsu Line described in 2.7.1.2 were for the straight section, except for the downgrade section exceeded 5 ‰. It was prescribed that the train should not be operated exceeding the limited speed for the curved track section, except for

33 Translated by T. A. Lab., Inc., Japan, Sept., 2019

the curved track in the turnout, the limited speed for the turnout, the limited speed for the downgrade section described in 2.7.1.3 in the downgrade track section, respectively. In addition, there were the limited speed by the railway signaling, i.e., the signal indications by the fixed signals such as the home signal, the starting signal and the block signal, by the speed limit indicator, and by the signal for work site such as the slow speed signal etc. If these plural limited speeds were applied in the section, the slowest limited speed is treated as the limited speed in the section. Here, these limited speeds were prescribed in the "Implementing Standards of Handling Train Operation", hereinafter referred to as the "Implementing Standards for Operation", a part of the Reported Implementing Standards in the rules of the Company, hereinafter the regulations without particular notes are the regulation prescribed by the Head Office of the Company, and the "Table of the operating velocity of the train". Here, the limited speeds were fived as the multiple of 5 km/h.

2.7.1.2. The maximum velocity The maximum velocity of the train was set as the lower velocity in the maximum operating velocity described in Table 8 and the maximum allowable velocity for each vehicle type. The maximum operating velocities of the train were prescribed in the Implementing Standards for Operation as follows. Volume 2. Operation of trains Chapter 25. Train operation etc. Article 238. [The maximum velocity of the train] The train should not be operated in the velocity exceeding the maximum operating velocities prescribed in the table of the operating velocity of the train. A part of the maximum operation velocity related to the concerned train in the table of the operating velocity of the train were indicated in Table 8.

Table 8. The maximum operating velocities of the train, extracted. Train category High performance train Other Line High performance Other high perfor- train name Section prior train [km/h] mance train [km/h] [km/h] Between Niitsu & Shibata 95 Between Shibata & 120 Murakami Between Murakami & Uetsu 100 Imagawa main line Between Imagawa & Sanze 95 [Omitted] [Omitted] Between Sanze & Sakata 120 Between Sakata & Akita 95 Hakushin Between Shibata & Niigata 120 Line * The concerned train was the high performance train and the high performance prior train.

34 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Here, the maximum operation velocity was determined considering the category of the train, the conditions of the railway tracks and the train protection facilities etc. in each track section. The maximum allowable velocity for each type of the vehicle prescribed in the table of the operating velocity of the train was 120 km/h for the concerned train, i.e., the 485 series vehicle.

2.7.1.3. The limited speed in the downward gradient section The limited speed in the downward gradient section was prescribed in the Implementing Standards for Operation as that the train could be operated in up to the limited speed for the same downward gradient as the standard downward gradient*20 determined in the section between stations, even in the case that the gradient in the downward gradient section of less than 1 km long was steeper than the standard downward gradient. In addition, it was prescribed as that the limited speed, in the downward slope section of less than 5 ‰, for the train composed of the vehicles, whose maximum velocity were 120 km/h, and the axle braking ratio*21 was 100, was 120 km/h that is the maximum velocity. Here, the track in around the accident site was the downward gradient of 8.2 ‰, but the standard downward gradient of the up track between Sagoshi station and Kita-Anarume station of Uetsu Line was 4.2 ‰, and the axle braking ratio of the concerned train was 100, then the limited speed for the concerned train was the maximum velocity 120 km/h. *20 "Standard downward gradient" is the most steep downward gradient for the train in the gradients between two points distant 1 km each other in the section between neighboring stations, or the gradient between the centers of the stations if the distance between the neighboring stations was less than 1 km. *21 "Axle braking ratio" is the ratio of number of the axles that the braking force had acted to the number of the coupled axles in the whole train.

2.7.2. The Operation Control 2.7.2.1. Outline of the operation control It is prescribed for the conventional lines of the Company that the operation control of the trains should be implemented if necessary as to control operating velocity or to suspend train operation etc., when the disasters were anticipated by rain falls, snow falls, the strong wind as described in 2.7.2.2, etc., and the occurrence of the earthquake, etc. Here, the operation control of the Company due to the strong wind were prescribed in the following regulations etc. (1) The Implementing Standards for Operation (2) The regulations etc., of the Company's rules. (i) "Procedures for Operation Control etc., in the Disaster", regulation. (ii) "Handling in the Abnormal Weather etc.", the notification prescribed by Niigata Branch Office. (iii) "Procedures of Train Dispatcher in Abnormal Situation", prescribed by Niigata Branch Office.

35 Translated by T. A. Lab., Inc., Japan, Sept., 2019

(iv) "Handling Manual for Operation in Abnormal Situation, driver edition" (v) "On the methods of Operation Control etc., against Strong Wind in the Future" The Company revised the wind speed referring in the operation control due to the strong wind from the average wind speed to the instantaneous wind speed, in the "On the Guidance of Handling Operation" issued from the Head Office on September 1987.

2.7.2.2. Operation control due to the strong wind The operation control due to the strong wind was prescribed in the Implementing Standard for Operation as the followings. Volume 7. Accidents and Disasters Chapter 4. Abnormal Weather etc. Article 459. [Precaution etc., against the abnormal weather etc.] The precaution or the patrol of the tracks, the control method of the operating velocity etc., should be obeyed to the prescripts in the Procedures for Operation Control in the Disaster etc. There was the following descriptions in the Procedures for Operation Control in the Disaster etc., regulation. [Implementation etc., of the operation control] Article 5. The train dispatcher and the station master should implement the required arrangement promptly, such as to control train operating velocity or to suppress train operation, hereinafter referred to as "the operation control", based on the prescripts in the Implementing Standard for Operation or the decision of the chief of the Branch Office, when the disaster was anticipated by rainfall, snowfall, strong wind etc., or the earthquake occurred, and when received the reports from the facility maintenance commander or the electricity related dispatcher, hereinafter referred to as the "facility maintenance commander etc." or the chief of maintenance office in charge of maintenance of the railway track etc. 2. [Omitted] [Designation of the operation control section etc.] Article 9. The chief of the Branch Office should determine the required section for operation control and the method in advance when the disaster was anticipated by rainfall, swell of rivers, strong wind etc., or the earthquake occurred, based on the Security Standard against Disaster in the Tracks etc., regulation, the Facility Notification No.12 issued on July 1997, the Implementing Standard for Operation, the Company Notification No.44 issued on March 2002, the Procedure of Operation Control against rainfall, the Construction Notification No.596 issued on February 1989, the Procedure of Operation Control against Swollen River, the Construction Notification No.597 issued on February 1989, the Procedure of Operation Control against Earthquake, the Facility Track No.763 issued on December 2002, etc. 2. [Omitted]

36 Translated by T. A. Lab., Inc., Japan, Sept., 2019

In addition, there were the following prescripts in the "Handling against Abnormal Weather, notification", prescribed by the Niigata Branch Office. 5. Handling of operation control etc. against strong wind (1) Implementation of operation control etc. in the earlier control section. (i) The train dispatcher and the station master should control the operation velocity of the train less than 25 km/h, when the wind speed was found as above 20 m/s. (ii)The train dispatcher and the station master should suspend the train operation, when the wind speed was found as above 25 m/s. (iii) to (vi) [Omitted] (2) Implementation of operation control in the normal control section. (i) The train dispatcher and the station master should control the operation velocity of the train less than 25 km/h, when the wind speed was found as above 25 m/s. (ii)The train dispatcher and the station master should suspend the train operation, when the wind speed was found as above 30 m/s. (iii) to (iv) [Omitted] (3) Handling of relaxation or cancellation of the operation control. (i) The train dispatcher and the station master should resume train operation being controlled the operation velocity less than 25 km/h, after confirmed that the wind speed has not been exceeded the value to suspend train operation for over 30 minutes by the indicator etc., of the gust alarm indicating device etc. (ii) The train dispatcher and the station master should cancel the speed control for the train, after confirmed that the wind speed has not been exceeded the value to control operating velocity of the train for over 30 minutes by the indicator etc., of the gust alarm indicating device etc. Here, the section between Sagoshi station and Kita-Amarume station of Uetsu Line was prescribed as the normal control section in the attached table in the Handling against the Abnormal Weather etc., the notification", prescribed by Niigata Branch Office. In addition, the same contents were prescribed in the "Handling Manual for Operation in Abnormal Situation, driver edition", and in the "Procedures of Train Dispatcher in Abnormal Situation", prescribed by Niigata Branch Office, In addition, "On the Operation Control etc., in the Strong Wind in Future", issued by the Head Office of the Company in 1989, prescribed the monitoring system as follows. 1. Method of the operation control (1) Implementation of the operation control e. The monitoring system etc. The monitoring of the status of wind should be implemented for the wind speed 10 m/s lower than the value to cancel the train operation, i.e., above 15 m/s for the earlier control section and above 20 m/s for the normal control section.

2.7.2.3. Method of designating the operation control section

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The section to implement operation control due to strong wind was designated for the section between stations including the place where occurrence of the disaster was anticipated, and the 31 places were designated at the time of the accident in the existing line of the Company except for Shinkansen, in the territory of the Niigata Branch Office of the Company, who controlled mainly the Japanese Sea side in Niigata Prefecture and Yamagata Prefecture. The operation control sections due to strong wind that had been designated by the former Japanese National Railway were transferred to the Company when the Company had established, and revised in 1989, after implemented the investigation on the location of the anemometers responding the report by the Technology Investigating Committee for the Amarube Accident described in 2.11.2.

2.7.2.4. Designating method for the earlier control section The Company had been designated the earlier control sections due to strong wind for the section between stations including the place where occurrence of the disaster was anticipated, and designated 3 places at the time of the accident in the territory of Niigata Branch Office of the Company, i.e., between Niitsu station and Kyogase station including Aganogawa Bridge of Uetsu Line, between Teradomari station and Bunsui station including Shinanogawa Bunsui Bridge of Echigo Line, and between Hakusan station and Niigata station including Shinanogawa Bridge of Echigo Line. According to the Company, the earlier control sections due to strong wind were designated based on the investigation on the location of anemometers described in 2.7.2.3. In the investigation, the Branch Office etc., had designated the earlier control section by evaluating comprehensively the following conditions presented by the Head Office. a. The section where the strong wind is in the trend to blow abruptly, not the section where wind blows usually or the section where strong wind blows. b. The section such as the single track deck bridge considered as the critical wind speed of overturning is lower than as in the plane. c. The section where the train derailment or overturn due to strong wind occurred in the past. d. The section in the other particular situations, for example, the section where the measures to communicate the operation suspension due to strong wind to the running train, such as the train radio or the obstruction warning signal, were not equipped. Each Branch Office reviewed and classified the control sections into the sections to enforce control and the normal control sections. After that, the earlier control sections were determined in 1989, after examined in the Head Office.

2.7.2.5. Operation control due to strong wind in the railway and tram operators in the whole country The operation controls due to strong wind in the railway and tram operators in the whole country were summarized in the "On the results of the urgent general inspection on the anemometers located in the existing lines, prompt report", the material of the Railway Agency, Ministry of Land, Infrastructure, Transport and Tourism, published on March 3, 2006, as

38 Translated by T. A. Lab., Inc., Japan, Sept., 2019

follows. The 184 operators in total 188 operators had been prescribed the operation control due to strong wind. The company who had not prescribe the operation control due to strong wind were the category 3 operators, who owned the railway facilities but did not operate the trains, or the operators whose trains were operating only in the underground track section. The wind speeds to suspend train operation in the control section were 25 m/s in 57 % of the whole control section, i.e., about half control section, 30 m/s in 37 %, and 20 m/s in 5 %, respectively.

2.7.3. Summary of Handling Operation in Abnormal Weather Condition 2.7.3.1. Handling operation in abnormal weather condition The handling operation in abnormal weather condition in the conventional line of the Company were prescribed as to operate the train or the vehicle paying particular attention with strict cautions when the disaster was anticipated due to the rail fall, the snowfall, the earthquake, the strong wind etc., described in 2.7.3.2 to 2.7.3.4. Here, the handling operations in the strong wind were prescribed in the following regulations etc. (1) The Implementing Standard for Operation (2) The regulations in the Company (i) Procedures of Operation Control in Disaster, regulation. (ii) Handling in Abnormal Weather Condition, notification prescribed in Niigata Branch Office. (iii) Manual of Handling Operation in Abnormal Condition, driver edition. (iv) Procedures of Train Dispatcher in Abnormal Condition prescribed in Niigata Branch Office.

2.7.3.2. Handling operation in strong wind of the staffs engaged in the operation of train or vehicles or the maintenance of railway track. The handling operation of the staffs engaged in the operation of train or vehicles or in the maintenance of railway track in the situation of strong wind were prescribed in the Implementing Standards for Operation as follows. Volume 7. Accidents and Disasters Chapter 4. Abnormal Weather etc. Article 458. [Cautions in Abnormal Weather etc.] The staff engaged in the operation of train or vehicles or in the maintenance of railway track should pay the particular attention in the operation of train or vehicles and implement the strict cautions when there was the fear of the occurrence of a disease due to rainfall, snowfall, earthquake etc., or received the notification of weather information. Here, according to the Company, the word "the strict caution" was used as the attitude.

39 Translated by T. A. Lab., Inc., Japan, Sept., 2019

2.7.3.3. Handling operation of the driver in strong wind The handling operation of the driver in the strong wind was prescribed in the Implementing Standard for Operation as follows, in addition to the description in 2.7.3.2. Volume 7. Accidents and Disasters Chapter 4. Abnormal Weather etc. Article 464. [Measures of the driver when encountered strong wind while operating train] The driver should implement the following handlings (1) and (2) when encountered the strong wind while operating the train. (1) Don't apply emergency brake hard abruptly in the place of the violent wind so as not to change train velocity. (2) When recognized that the train operation was dangerous, to endeavor to stop the train in the safe area. In addition, the Handling Manual for Operation in Abnormal Situation, driver edition" prescribed the similar contents. Here, according to the Company, the Company has been instructed as follows. (1) The Company had been instructed as not to apply the strong braking abruptly when the driver applied the emergency brake as recognized as the violent windy place, but the Company had not been instructed the concrete validity to apply emergency brake. (2) The Company instructed to stop the train to avoid the section of bridge and high embankment etc., in the strong wind area, when the driver recognized that the train operation was dangerous. (3) The Company instructed to apply the emergency brake even in the strong wind, if the train should be stopped promptly as the signal had been indicating the stop signal etc.

2.7.3.4. Handling operation of the train dispatcher in strong wind The handling operation of the train dispatcher in the strong wind were prescribed in the Implementing Standards for Operation as follows, in addition to the descriptions in 2.7.2.2 and 2.7.3.2. Volume 7. Accidents and Disasters Chapter 4. Abnormal Weather etc. Article 461. [Handling in the wind speed of above 25 m/s] The train dispatcher or the station master in the station where the anemometer has been installed, should implement the following handlings (1) to (3), when it was found that the wind speed became to above 25 m/s. (1) The departure or passing through of the train should be suspended temporarily responding to the situation, when the train operation was considered as dangerous due to the strong wind etc. (2) to (3) [Omitted] Article 462. [Handling in the wind speed of above 30 m/s]

40 Translated by T. A. Lab., Inc., Japan, Sept., 2019

The train dispatcher should instruct to suspend the train operation temporarily when recognized that the wind speed became to over 30 m/s based on the Weather Notification or the notification from the station master of the station where the anemometer was equipped. In addition, the Procedures of Train Dispatcher in Abnormal Condition, prescribed in Niigata Branch Office, prescribed the similar contents. Here, according to the Company, the handling of the station master and the notification from the station master prescribed in the Article 461 and the Article 462 of the Implementing Standards for Operation were not abolished, but the notification from the station master had lost its necessity because the train dispatcher can implement the operation management comprehending the information on the anemometers etc., in the display of the PreDAS described in 2.5.7, after it was introduced. The Company planned to review the regulations suitably on the difference between the actual situation and the Implementing Standards for Operation, as it is not determined to revise the regulations immediately.

2.7.4. Implemented Status of Operation Control at the Occurrence of the Accident As described in 2.1.4 (2) and (3), the chief train dispatcher stated that the operation control due to strong wind was not applied at the occurrence of the accident and there was no report on the abnormal weather condition from the train crews in the time slot around the occurrence of the accident, and the supervising dispatcher stated that there was no alarm sound for Uetsu Line in the PreDAS in the accident day.

2.7.5. Measures at the Occurrence of the Accident The measures at the occurrence of the accident of the train in the existing line of the Company was prescribed as to endeavor prevention of the the accompanied accidents, rescue and saving lives and notify to the related sections etc. Here, the measures to the occurrence of accident were prescribed in the following regulations. (1) The Implementing Standards for Operation (2) The regulations etc., in the Company (i) Procedures to Measure the Operation Accidents etc., regulation. (ii) Procedures to Measure Temporary against Accidents and Disasters in Niigata Branch Office, prescribed by Niigata Branch Office. (iii) Handling Manual for Operation in Abnormal Situation, driver edition. (iv) Handling Manual for Operation in Abnormal Situation, conductor edition. (v) Guidance for Train Dispatcher, prescribed in Niigata Branch Office. (vi) Procedures of Train Dispatcher in Abnormal Situation, prescribed in Niigata Branch Office.

2.8. Information on Weather etc. 2.8.1. The Meteorological Summary on the Accident Day [Refer to Attached Figure 17, 18]

41 Translated by T. A. Lab., Inc., Japan, Sept., 2019

According to the material of the JMA, the growing low pressure on the sea in the west of Hokkaido had been moving to east, and the cold front had been expanded from the low pressure to the southern Korean Peninsula via mid of the Japanese sea, at 15:00, December 25, 2005. The cold front passed Tohoku district at night and moved to the Pacific Ocean before dawn. Therefore, the weather condition in Shonai area in Yamagata Prefecture, hereinafter referred to as "Shonai Area", including the accident site was in the warm area*22 of the low pressure, at 19:00, December 25, 2005. In addition, Yamagata District Meteorological Observatory had been issued the warnings and advisories shown in Table 9, to the Shinai Area, in the meteorological summary on December 25.

Table 9. Warnings and advisories for Shonai Area issued by Yamagata District Meteorological Observatory Issued time and date Issued warnings Issued advisories 06:50, Dec. 25 Snowstorm, Heavy seas, Thunder, Avalanche 15:24, Dec. 25 Blizzard, Heavy seas Thunder, Avalanche 21:44, Dec.25 Blizzard, Heavy seas Heavy snow, Thunder, Avalanche, Snow accumulation

According to the observed results by the geostationary meteorological satellite on 19:00, December 25, the array of the clusters of the clouds whose top was about 4 to 6 km high, had been expanded from northern part of Japanese Sea toward south-west direction. The array had passed Tohoku district after evening of the day. Here, according to the records of the JMA, the sensed earthquake was not observed in Yamagata Prefecture on the accident day. *22 "Warm area" is the warm side area surrounded by the cold front and the warm front extended from the mid latitude cyclone, the warm and wet air are easily entered.

2.8.2. Weather Observation on the Ground [Refer to Attached Figure 19, 20] According to the observed records in Sakata Weather Station, JMA, located about 7 km WNW from the accident site, the weather condition in 18:00 to 20:00, December 25, was as shown in Table 10.

Table 10. Observed records in Sakata Weather Station on December 25. Max. instantaneous Atmospheric 10 minutes average Precipitation pressure value in past 1 hour Tempera- Time Weather in the past 1 reduced to Wind Wind ture [℃] Wind Wind hour [mm] mean sea speed speed direction direction level [hPa] [m/s] [m/s] 18:00 Thunder 0.0 1001.7 5.6 10.1 SW 23.6 SSW 19:00 Rain 1.0 1000.6 6.3 7.2 SW 19.7 SW 20:00 Rain 1.5 1000.9 4.5 10.7 WNW 21.6 WSW

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* The anemoscope and anemometer were located at a height of 27.5 m from the ground surface.

Here, the cumulonimbus clouds were observed in the sky by the visual observation at 18:00, December 25. In addition, the thunder and lightning*23 of the intensity class 1 was observed less than 5 km distant in east at 19:00, December 25, the thunder and lightning had been continued from 19:00 to 19:50. In addition, according to the observed record in the branch of the JMA in Shonai airport at Hamanaka, located about 13 km distant in SW from the accident site, the weather condition from 18:00 to 20:00, December 24 were as shown in Table 11. *23 "Thunder and lightning" is the situation that the light and the sound, i.e., the lightning and the thunder were observed at the same time when the thunder had occurred. The intensity of the thunder and lightning was defined as follows. The intensity 0 is the level that the thunder could be recognized, the intensity 2 is the level that the violent thunder terrified the persons, and the intensity 1 is their intermediate level.

Table 11. Observed records in Shonai Airport Branch at Hamanaka, on December 25. Max. instantaneous Atmospheric 10 minutes average Precipitation pressure value in past 1 hour Tempera- Time Weather in the past 1 reduced to Wind Wind ture [℃] Wind Wind hour [mm] mean sea speed speed direction direction level [hPa] [m/s] [m/s]

18:00 Rain 1.0 1000.9 5.7 11.3 SW 24.7 W Accompanied 19:00 1.0 999.9 5.7 11.8 SSW 21.6 SW thunder & sleet 20:00 7.0 1000.4 4.5 12.3 WNW 23.1 WSW * The anemoscope and anemometer were located at a height of 10 m from the ground surface. * Wind speed in the table was the round number transformed from the record in [kt] by "1 kt = 0.5144 m/s"

Here, the cumulonimbus cloud was observed in the sky by the visual observation at 18:00 and 19:00, December 25, 2005. Furthermore, the thunder and lightning of intensity 2 was observed in the zenith at 19:00 of the same day. The thunder and lightning had been continuing from 18:37, and direction of the thunder and lightning changed from SW to the zenith as the time passed. Furthermore, it was hail from 19:02. In addition, the areas where the wind direction were around western and southern were closed each other as their border was around Shonai Area, in the distribution map of the wind direction and wind speed averaged for 10 minutes, distributed form the JMA AmeDAS, i.e., Automated Meteorological Data Acquisition System, in Yamagata Prefecture and its surroundings, and the border of these areas moved to the SE direction in the Shonai Area slowly.

2.8.3. Observation of Wind Direction and Wind Speed in around the Accident Site According to the records of the existing anemometer of the Company, closest to the accident site, the maximum instantaneous wind speed was 12 m/s in one hour from 18:15 to 19:15 of the

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accident day, which was not reached to the value that the operation control should be applied, and recorded at 19:02 in the latest to the occurrence of the accident. Here, the wind speed of 20 m/s which was the value to establish the monitoring formation, was observed at 19:17 after the occurrence of the accident. In addition, the anemoscopes and anemometers had been installed by the national organization, the local governments, the private enterprises, etc., in addition to the existing anemometers of the Company and the weather observing points of the JMA described in 2.8.2, in around the accident site. The summary of the maximum instantaneous wind speed and the maximum wind speed*24 between 18:30 to 19:30, December 25, in these measuring instruments were as follows. The maximum instantaneous wind speed was 36.9 m/s measured in the Shinkawa Beach at 19:07. There was no other observing point where measured above 30 m/s, the maximum values observed in many observing points were 20 to 25 m/s. The largest maximum wind speed was 19.9 m/s measured in off Sakata at 18:50. The maximum wind speeds measured in the other measuring points were less than 20 m/s. [Refer to Attached Figures 21-I, 21-II, 22-I, 22-II, 23] *24 The wind speed is defined as the distance of the atmosphere moved in the unit time. The wind speed was observed as the instantaneous value and the averaged value as the wind changes incessantly. The wind speed at some time is called as the instantaneous wind speed. The value averaged the wind speed within a certain time is called as the average wind speed, the time to average is set as 10 minutes, usually. The maximum wind speed is defined as the maximum value of the average wind speed in a certain period, and the Maximum instantaneous wind speed is defined as the maximum value in the instantaneous wind speed in a certain period.

2.8.4. Observation by the Meteorological Rader [Refer to Attached Figure 24, 25-1 to VI] According to the observation by the meteorological radar before and after 19:00, December 25, the linear radar echo*25, hereinafter referred to as "the echo", was observed from NE to SW direction in the sky in around the accident site, and there were plural echoes indicating heavy rainfall intensity exceeded 50 mm/h in a part of the echo. One of the strong echoes was existed close to the belt shaped area where damaged by the strong wind described in 2.8.6, moved to ENE direction, and passed around the accident site based on the observation by the meteorological radar at about 19:15. The vertical distribution of the echo showed that the height of the echo when the echo passed around the accident site had reached to about 6 to 8 km in the sky. *25 The meteorological radar observes rain or snow existed in the wide area of about several hundred km radius, by emitting the radio wave, called as the micro wave, by rotating the antenna. The radar echo is the spatial distribution of the radio wave returned after reflected by rain or snow. The intensity of the radar echo corresponds to the amount of rain or snow existed in inside of the clouds.

2.8.5. Observation by the Wind Profilers [Refer to Attached Figure 26] According to the observation of the wind profiler*26 in Sakata Observatory, the wind direction had changed from SW to W in the height below 1 km from 19:00 to 19:10. *26 "Wind profiler" is the device to measure the wind direction and the wind speed in the sky by emitting

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the radio wave from the ground toward the sky and receiving and processing the returned radio waves scattered by the turbulence of the wind in atmosphere.

2.8.6. Damaged Status due to Strong Wind in around the Accident Site The investigation on the weather conditions and the damaged status due to strong wind were implemented as the damages considered as caused by strong wind had occurred in around the accident site in the night of the accident day. The damages considered as caused by strong wind were distributed as dotted from seaside, Hamanaka area of Sakata City, to about 14 km distant toward ENE, Ishinazaka area of Sakata City, and concentrated in the belt shaped area of some 10 m to some 100 m wide. The damaged status in each area was as follows. Here, the correct time of the occurrence of damages could not be identified including the damages which could not be confirmed as damaged at night of the accident day, because many damages were found in the next morning of the accident day. (1) Hamanaka area and Kuromori area, about 9 to 11 km WSW from the accident site The windbreak fence and the windbreak forest etc., were damaged continuously in these areas. Each damage was as follows. (i) Windbreak fence The wooden windbreak fence, about 1.2 m high, installed in N-S direction in around the beach, which was planted about 700 m north form estuary of Akagawa river fell off toward east for about 20 m long. (ii) Windbreak forest There were damages as 53 fallen trees and broken boughs in the windbreak forest between seaside and Yamagata motorway, many fallen trees fell toward east or north. There were the places where the woods fell toward north and the place where the woods fell toward east were located close to each other. Among the damages due to strong wind, the Japanese black pine of about 20 m height was wound and broken at a height of 2 to 3 m, and the tip of the upper trunk fell toward NE direction. (iii) The Vinyl house There were damages as plural vinyl houses were crushed and collapsed in this area. In addition, there were damages as the frame pipes of the vinyl houses were raised up or the damages as the props came off with its foundations from the ground. In addition, there were damages as the joint of the pipes in upper center of the vinyl house and the vinyl ceiling were broken as expanded. (2) Hirono area, about 6 km WSW from the accident site (i) Wooden windbreak fence The northern part of the wooden windbreak fence fell off toward east for about 35 m long, in the total 50 m long wooden windbreak fence installed in N-S direction in Hirono area. (ii) Snow-break fence along national highway No.7 The snow-break boards of the snow-break fence installed in west side of national highway No.7 were scattered by the strong wind at about 19:00, and the stores etc., in east

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side of the highway were damaged by the snow-break boards. The staff of the store stated that the electric power failed at about 19:10 in the store. According to the material of the Sakata Office of River and National Highway, MLIT, the snow-break boards were scattered in the range of about 21 m, the snow-break boards in about 84 m suffered the effects such as being scattered or wound. Among the section where the snow-break fence had been installed continuously for 473 m, the damages were concentrated in the small section. The snow-break fences were designed to endure against instantaneous wind speed 40 m/s, and constructed in 1989. Here, the maximum value of the maximum instantaneous wind speed in winter season, i.e., December to March, after 1989 fiscal year in Sakata Observatory, close to this area, was 35.8 m/s WSW, on December 13, 1991. (ii) Others There were damages that a part of the tin roof of the houses had come off, and the TV antennas had wound. (3) Itado area, about 4 km WSW from the accident site There were the damages as a part of the plywood walls of the houses had come off, the roof tiles of the working cabin had been raised up, the vinyl houses had damaged, the TV antennas had fallen etc. (4) Marunuma area, about 4 km WSW from the accident site There were damages as the tiles of the wall of the entrance of the house had dropped and the branch of the pine trees had broken. (5) Enoki area, in around the accident site (i) Shed for agricultural machinery The shed for agricultural machinery, about 11.7 m long, about 5.4 m wide and about 3 m high, located on about 40 m west from the up track, was collapsed in around 158,200 m, close to the accident site. The roof of the shed for agricultural machinery had been blown off to the slope of the embankment of down track of Uetsu Line about 10 m east from the shed for agricultural machinery. In addition, the wall panels and the pulled out steel props with concrete foundation buried in the ground and the tin plate walls, had been scattered in east to north directions of the shed for agricultural machinery, and some had been blown off to about 70 m NE crossed the up track of Uetsu Line. According to the onsite investigation and the analysis*27 based on the wind tunnel test etc., implemented by Professor Tamura, Tokyo Polytechnic University, etc., it is supposed that the shed for agricultural machinery had received the wind from SSW direction and the whole shed had been raised up as the concrete foundations had been pulled out, and broken into pieces and scattered and that the instantaneous wind speed at that time would be over 34 m/s, based on the scattered direction etc., of the heavy objects such as the outer wall accompanied with the concrete foundation blocks etc. (ii) Others There were damages as the roof tiles of houses had come off, the antennas had fallen and

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the vinyl houses had collapsed, in about 300 m to 700 m ENE from the accident site. Here, there was no damage for the poles and electric cables in around the accident site. (6) Chigawara area, about 1.5 km ESE from the accident site There was the damage that a part of the vinyl house had damaged. (7) Ishinazaka area, about 3 km ENE form the accident site There were damages as the vinyl houses had collapsed or partly damaged, the cabin had overturned, and the TV antennas had wound. [Refer to Attached Figures 27 to 31, 32-I, II, 33-I, II] *27 Y. Tamura, et. al., "Estimation of the wind status in around the derailment site of Inaho 14, Uetsu Line, December 25, 2005", Japan Association for Wind Engineering, Vol.32, No.2, April 2007, in Japanese.

2.8.7 Information from the Persons etc., Relevant to Weather etc., at the Occurrence of the Accident The hearing statements on the weather before and after the occurrence of the accident for many inhabitants etc., in the damaged area due to strong wind described in 2.8.6, had been implemented in addition to the hearing statements for the train crews and the passengers described in 2.1. The summaries of the statements were as follows. (1) Weather of the accident day The concerned driver, the passengers, and the station staffs of Sakata station stated the various information on the weather before and after the departure of the concerned train from Sakata station, as follows. (i) It was sleeting etc., in addition, it was thundering. (ii) It was the sound as snow etc., hit the vehicles while the train was running. (iii) It was strong wind and cold in Sakata station. (iv) Usually, this area is windy. The wind was not particularly strong on the accident day. (v) The wind in Sakata station was not felt so strong, it was the usual situation. In addition, many inhabitants in the areas damaged due to strong wind stated as it was severe thundering with strong wind and the strong wind blew abruptly with roaring sound, etc. (2) Weather condition at the accident site The concerned driver and the plural passengers stated on the situation just after the concerned train had passed the concerned bridge as follows. (i) The wind blew strong abruptly just after the concerned train had passed the concerned bridge. It was terrible snowstorm blown up from the ground by the wind from right, and something as white wind hit the driving cab as to wrapped. (ii) There were the sound as something hit the right window glasses as "pop-pop". (iii) The wind blew into the cabin abruptly. In addition, the inhabitants in the damaged area due to strong wind stated that it was the terrible sound at about the occurrence of the accident.

2.8.8. The Phenomena to Couse the Damages due to Strong Wind Generally, the phenomena to cause the damages due to strong wind were the tornado, the

47 Translated by T. A. Lab., Inc., Japan, Sept., 2019 down burst, the gust front*28, the dust devil*29 etc. Among these, the phenomena caused many local severe damages are the tornado and the down burst, and there was the case that the tornado and the down burst were generated in the same cumulonimbus cloud. The features of the tornado and the down burst were as follows. (1) Features of the damages and the phenomena due to the tornado (i) The wind direction supposed by the damaged traces had the trends to rotate or to converge. (ii) Some people felt abnormal in their ears as the atmospheric pressure decreased rapidly. (iii) There were many cases that the damaged areas were in belt shape or linear shape. (iv) There were many cases that the remained flown objects or collapsed objects fell to the same direction when the tornado moved fast, fell to various directions when the tornado moved slow, fell to various directions in around the center of the whirl even when the tornado moved fast, and the light objects remained to be gathered in a point or in a line. (v) There is the case that the objects had stirred up high in the sky and sometimes the scattered objects had reached to distant places. (vi) There are many cases that the roared sound as a jet plane before or after the occurrence of the gust of wind. (2) Features of the damages and the phenomena due to the down burst (i) There were many cases that the wind direction estimated from the damages were the same or to spread radially from the certain point. (ii) The damaged area spread wide in the plane. (iii) The scattered objects flew mainly to the lee side. (iv) There was no special sound, or sometimes there was the cases to hear the sound at the same time of the occurrence of the gust. In addition, the Fujita Scale indicated in Table 12 was widely used as the standard to estimate the scale of the strong wind simply and easily from the damaged status due to strong wind. Here, the Fujita Scale was contrived in 1971, and it is strongly reflected the natural condition and characteristics of the houses of the Unites States at that time, then, it is not always appropriate to estimate scale of the strong wind for the present Japanese situation. *28 In the cumulonimbus clouds in the maximum scale stage or in the weakened stage, the air cooled by melted of evaporated particles of falling water were accumulated in the lower part of the cloud, on the other hand the local anticyclone was performed on the ground surface and the cold air flows to the circumference. "Gust front" is the front edge of the flowing cold air, the gust of wind blow and the temperature decreased rapidly when the cold air had passed. *29 "Dust devil" is the strong whirls around the vertical axis sometimes observed in the bare field such as the desert etc., in the daytime of the clear weather day. It is considered as caused by the rising air heated in around the ground surface, different from the tornado which was excited by the convective cloud in the sky.

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Table 12. Relationship between the Fujita scale and damages*30 Rank Supposed wind speed Damages

17 to 32 [m/s] The weak structure sch as the TV antenna etc., was fallen. Twigs F0 were broken, and the trees with shallow roots might be tilted. The Average of about 15 s. house without inhabitant might be broken. The roof tiles were blown out, the window glasses were broken. The 33 to 49 [m/s] vinyl houses had seriously damaged. The trees with weak roots had F1 fallen, and the trunk of the tree with strong root might be broken. Average of about 10 s. The running car was blown over from the road being acted by the side wind. Roofs of houses were removed, and the weak houses without 50 to 69 [m/s] inhabitant were collapsed. The big trees were blown over or F2 Average of about 7 s. wrenched away. Cars might be blown away from road and train might be derailed. Houses may collapse as walls were pushed down. Housed without 70 to 92 [m/s] inhabitant may scatter in pieces, even the steel frame house may F3 collapse. Trains are overturned and cars are lifted and blow off. Average of about 5 s. The greater part of the big trees in the forest are broken or fall over, and some trees may be pulled out. Houses with inhabitant are broken in pieces and are scattered in 93 to 116 [m/s] around, and the weak houses without inhabitants are blown away F4 without vestige. The steel frame houses also collapsed. Trains are Average of about 4 s. blown away and cars fly in the air for some ten meters. The objects of over 1 ton fall on our head and it is the most dangerous. Houses with inhabitant are blown away nothing remained, the 117 to 142 [m/s] barks of standing trees had removed away. Cars and trains were F5 Average of about 3 s lifted up and flew in the air, and flown away to the incredible distance. The object of some tons flew from somewhere.

*30 The Meteorological Society of Japan, "Encyclopedia of Meteorological Science", Tokyo Shoseki Co. Ltd., p.466, 1998, in Japanese.

2.9. Information on the Evacuation and the Rescue Activities 2.9.1. Actions of the Train Crews just after the Occurrence of the Accident As described in 2.1.2 (1), the concerned driver stated that he asked the passenger to arrange the dispatching of the ambulance, and he checked the status of the injured persons and asked the train dispatcher using the business mobile phone of the concerned conductor to arrange dispatching of the ambulance. As described in 2.1.2 (2), the concerned conductor stated that he moved the passengers to secure safety of the passenger, he checked the status of the injured persons dividing works with the concerned driver, and assisted the injured person rescued by the rescue team to get on the ambulance. Here, some passengers stated that the concerned driver served to the rescue activity for passengers as his head was bleeding.

2.9.2. Actions of the Train Dispatcher just after Occurrence of the Accident As described in 2.1.4 (1), the train dispatcher stated that he instructed the concerned driver to

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comprehend the number of injured persons and their injured status in cooperation with the concerned conductor, as he received the communication from the concerned driver that "it was gust of wind on the bridge and derailed, the front three vehicles were completely demolished, there were many injured persons, please arrange to dispatch ambulance" at about 19:30. In addition, as described in 2.1.4 (2), the chief dispatcher stated that he had instructed to communicate to Sakata station and explain the situation and to gather the staffs. Furthermore, as described in 2.1.4 (3), the supervising dispatcher stated that he asked the Police Headquarters of Yamagata Prefecture to dispatch policemen and arrange to dispatch ambulance, immediately, after he received the 2nd report at about 19:20.

2.9.3. Actions of the Company just after the Occurrence of the Accident 2.9.3.1. Actions of the Company just after the occurrence of the accident The Company had been prescribed the "Procedure of measurement against operation accident etc., regulation" as the measures against the occurrence of accident and disaster, and Niigata Branch Office had been prescribed the "Procedure of the temporary process against accident or disaster in Niigata Branch Office, regulation". These regulations prescribed to set up the Onsite Management Headquarter with the district manager as the director of the headquarter at the accident site, and the Disaster Management Headquarter with the director of the Branch Office as the director of the headquarter in the Branch Office, respectively, when the accident significantly affected the transportation had happened. According to the Company, in Niigata Branch Office, the Disaster Management Headquarter with the director of Niigata Branch Office as the director of the headquarter was set up at 20:00 of the accident day, and this formation has been continued at this moment. At 20:32 of the same day, the deputy station master for general service of Sakata station arrived at the accident site, then, he was assigned to the Onsite Manager at 21:21. At 22:22 of the same day, Sakata district manager arrived at the accident site and set up the Onsite Management Headquarter with the Sakata district manager as the director of the headquarter, and at 04:40 of the next day, December 26, the Deputy Director of Railway Business Headquarter of the Head Office took over the director of the Onsite Management Headquarter from Sakata district manager. This formation had been continued until the Onsite Management Head Office had dissolved on January 19, 2006. In addition, the Head Office Management Headquarter with the President as the director of the headquarter was set up at 20:20 of the accident day, as it was not prescribed by the regulations in the Head Office.

2.9.3.2. Actions of the Company staffs boarded on the concerned train as the passenger There were 6 company staffs boarded on the concerned train, and the hearing statements were implemented from 4 staffs. Among the 4 company staffs, 2 staffs who did not lose their consciousness stated that they served for the activities to rescue injured persons in cooperation

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with the other passengers.

2.9.4. Actions of the Emergency Rescue Organization etc. 2.9.4.1. Notification of the accident and the first actions The Fire Defense Headquarter of Sakata District Fire Defense Union, hereinafter referred to as the "Sakata Fire Defense Headquarter", recognized the occurrence of the accident by the report from the passenger at about 19:16 on the accident day, and immediately dispatched the staffs. The commander team and the rescue team arrived at the accident site at about 19:32. In addition, the Sakata Fire Defense Headquarter implemented the emergency call up for all staffs and dispatched the emergency team and the rescue team etc., additionally, and asked the assistant dispatch to the Fire Defense Headquarters in the Prefecture. On the other hand, the Police Headquarters of Yamagata Prefecture recognized the occurrence of the accident by the report from the passenger at about 19:17, and instructed Shonai Police Station to go into actions. The Shonai Police Station, as received the instruction, immediately dispatched staffs and set up Onsite Management Headquarter.

2.9.4.2. The emergency rescue formations (1) The emergency rescue organizations The Sakata Fire Defense Headquarter, the Fire Defense Headquarters in Yamagata Prefecture such as Yamagata City Fire Defense Headquarter and Tsuruoka City Fire Defense Headquarter etc., received the request from Sakata Fire Defense Headquarter on the assistant dispatch, implemented the rescue activities under the control of the Onsite Headquarter whose supervising commander was the director of the Onsite Command Headquarter of Sakata Fire Defense Headquarter. Here, the total of 140 teams and 652 staffs were dispatched form December 25 to 31, from the Fire Defense Headquarters in Yamagata Prefecture represented by Sakata Fire Defense Headquarter. (2) The medical institutions The Sakata Fire Defense Headquarter asked the 4 hospitals, located close to the accident site within the 5 emergency designated hospitals in the territory, to accept the injured persons at about 19:30 and transported the injured persons to the 3 hospitals. (3) Police Headquarters of Yamagata Prefecture Police Headquarters of Yamagata Prefecture dispatched the members to the accident site and implement the transportation of the injured persons and the bodies, the traffic control in around the accident site, etc., and set up the Affair Management Headquarter in the Police Headquarter of Yamagata Prefecture at 19:50. Here, the total of about 700 members were dispatched to the rescue activity and the search activity from December 25 to 31, from the Police Headquarter of Yamagata Prefecture. In addition, Police Headquarter of Miyagi Prefecture dispatched the total 45 members from December 27 to 29, as the wide area emergency assist team.

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(4) Shonai Town The Shonai Town, as recognized the occurrence of the accident, transported the stretchers, blankets, drinks etc., to the accident site.

2.9.4.3. Summary of the emergency rescue activities (1) The communication dispatcher room of Sakata Fire Defense Headquarter communicated with Sakata station and confirmed that the operation suspension of the related trains had been implemented and the power feeding had been stopped at about 19:31, and communicated that to the rescue team dispatched to the accident site using the radio device. (2) The rescue team arrived at the accident site at about 19:32, after confirmed the situation of the accident, entered to the cabin from the front of the completely demolished 1st vehicle and implemented the triage*31 of the injured persons. The rescue team arrived at the accident site at about 19:42, divided into two groups and entered the 1st vehicle from front and rear of the vehicle. The group entered from the front joined to the rescue team already arrived and implement the rescue activities, on the other hand, the other group entered the cabin from rear of the 1st vehicle and implemented rescue activity. (3) The air tents were set up as the first aid station in around the accident site, the aiding activities were implemented in the worse situation as the air tents had broken etc., because the weather at the occurrence of the accident was severe blizzard. (4) The transportation of the injured persons to the hospitals had started about 20:00 of the accident day. The medical care team arrived at about 20:50 and joined to the rescue activity and implemented the medical treatment in the accident site. The injured persons, except for an injured person who had been sandwiched between the cabin facilities and difficult to be rescued, had been transported to the hospitals by about 21:00. (5) The injured person, who had been sandwiched between the cabin facilities and difficult to be rescued, was rescued using the hydraulic rescue tools as being dosed with the medicine for prevention of the crush syndrome*32. Here the transportation of all injured persons to the hospitals were completed at about 23:55. (6) On December 26, the rescue team implemented the visual inspection for the inside and outside of all vehicles in cooperation with the Police Headquarter of Yamagata Prefecture. As for the 1st vehicle, the inspection using the fiberscope was also implemented but no one was found, then the searching activity of the day was ceased at about 18:30, December 26. (7) In the searching activity implemented on December 28, a body was found underneath the center of the 1st vehicle, and accommodated at about 20:00, December 27. *31 "Triage" is the decision of the priorities for the treatment or transportation to hospital by judging the urgency and the degree of serious wound of the illness or the injuries. *32 "Crush syndrome" is the symptom such as the acute renal insufficiency or multiple organ failure occurred after rescued due to being induced the muscle failure caused by the skeletal muscle of the limbs and the thigh being suppressed for a long time etc..

2.10. Information on the Train Protection etc.

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2.10.1. Outline of the Train Protection The train protection is the measures to stop the train before the hindered place by the emergency brake even if the train was running in the maximum velocity in the section, by indicating the stop signal against the train running toward the hindered place using the fuse, the rail clamp shunt*33, the train protection radio device, etc., in order to prevent the accompanied accidents when the train hindered the neighboring track by the derailment etc., or the facility had troubled. *33 "Rail clamp shunt" is the conductive wires with the magnets in its both ends, to make the similar status as the train existed in the track circuit by short-circuited the rails.

2.10.2. Handling of the Train Protection The Implementing Standard for Operation of the Company prescribed on the train protection as follows. Volume 2. Operation of trains Chapter 2. Train protection Article 16. [Method of train protection etc.] When the necessity to stop with haste the related trains had happened due to the derailment or overturn of the train, troubles in the track, etc., the train protection etc., should be implemented by the following (1) and (2). (1) When the fuse for the vehicle and the train protection radio device can be used, the stop signal should be indicated by the fuse for the vehicle and the train protection radio device before implement the train protection procedures. (2) Implement the train protection procedures by the following (i) or (ii). (i) When the stop signal can be indicated in the signal device by short-circuit the track circuit, rush to the place in the direction of the signal device planted before the hindered place, as indicating the portable fuse or the portable obstruction warning signal device, then, indicate the stop signal by the portable fuse or the portable obstruction warning signal device in the place where the approaching train can easily find, then, short-circuit the track circuit, where the train is approaching, by the rail clamp shunt, etc. (ii) Rush to the place over 600 m apart from the hindered place in the direction to the approaching train, as indicating the portable fuse or the portable obstruction warning signal device, then, indicate the stop signal by the portable fuse or the portable obstruction warning signal device. In addition, the Manual for Train Operation prescribed as follows. II. Train Operation 2. Train protection No.12 [Person in charge of train protection when hindered the neighboring track] The train protection, when hindered the neighboring track due to derailment or overturn of the train, should be charged as designated in the following (1) to (3).

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Here, when the train protection for the trains in the charged direction can be omitted by the direction of the train running in the neighboring track or the hindered situation etc., cooperate the train protection for the opposite direction. (1) The driver is charged on the direction where the driver is staying. (2) The staff boarding to implement the train protection is charged on the opposite train to the direction where the driver is staying, including the driver who are not in charge of driving when two drivers were boarded. (3) [Omitted] Furthermore, the Handling Manual for Operation in Abnormal Situation, driver edition and the Handling Manual for Operation in Abnormal Situation, conductor edition prescribed as follows. 2. Method of Train Protection (1) Method of Train Protection a. Send the radio by pushing the push button of the train protection radio device. b. Ignite the fuse for vehicle. [Note] - The fuse should be placed in the good visibility. - The diver owed the protection of the forward direction. But, the conductor should do it when the driver could not do it due to some reasons. - [Omitted] - [Omitted] (2) Ignite the portable fuse for vehicle and bring it with its bottom up, rush to the place of good visibility, and plant it besides the track. [Note] - When the approaching train was found while running, rotate the fuse in circular. (3) Set the rail clump shunt in the neighboring track. (4) After implemented the above items (1) to (3), report to the dispatcher and restore the train protection radio obeyed to the instruction.

2.10.3. Handling of the Train Protection Radio Device by the Conductor The Implementing Standard for Conductor of the Company prescribed as follows. I. Method of implementation, etc. 6. Others (1) Handling of the radio devices Items Contents of the works Remarks Train protection 1. Confirm lighting of the power lamp. [Omitted] radio 2. Push switch if the train protection is required. 3. Communicate with the driver and the dispatcher if the train protection was issued. 4. Communicate to dispatcher when the train protection became to no need, and restore it after received the instruction. Train radio [Omitted] [Omitted]

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Crew radio [Omitted] [Omitted]

2.10.4. Contents of the Education on the Train Protection in the Company According to the Company, the train protection is not needed fundamentally when the neighboring track was not hindered, but the train protection should be implemented when it could not be determined the necessity of the train protection instantaneously. In addition, when the neighboring track in the double track was hindered in the automatic block sections, as in the concerned accident, the regulation prescribed that the conductor can skip the train protection procedure in the engaged direction, and the conductor operate the train protection for the opposite direction when received the request from the driver and judged as necessary because he could not communicate with the driver. Here, the procedures of the train protection were as prescribed in the Handling Manual for Operation in Abnormal Situation, conductor edition, described in 2.10.2, i.e., the communication to the dispatcher should be implemented after completed the train protection procedures. In addition, there were some staffs, engaged in training in Niigata Branch Office at the time of the occurrence of the accident, stated that the fundamental order was from protection, rescue, and communication, but instructed to measure by changing the order depending on the circumstances based on the judgement of the train crews corresponding the situation of the accident site. The Company implement the education using the teaching materials in the train crew training program etc., that there is a possibility of the necessity of the protection for the own track in addition to the protection for the neighboring track.

2.10.5. Handling of Train Protection Radio Device by Train Crews of the Concerned Train As described in 2.5.4, there were the records of sending alarm signal from the train protection radio device at 19:15, December 25, in the train protection radio device in the 6th vehicle of the concerned train. As described in 2.1.1 (1), the concerned driver stated that he looked for the train protection radio device jus after the occurrence of the accident, but he could not find it because it was dark in the driving cab. As described in 2.1.2 (2), the concerned conductor stated that he sent the alarm signal by the train protection radio device because there was no communication from the concerned driver and he pushed the buzzer of the on-train communication buzzer but there was no response, and reported to the train dispatcher in Niigata that he sent the alarm signal by the train protection radio device because the concerned train emergency stopped between Sakata station and Amarume station.

2.10.6. Handling of Train Protection by the Crews of the Concerned Train As described in 2.1.2 (1), the concerned driver stated that he did not implement the measures such as to attach the rail clamp shunt or to ignite the portable fuse etc. as the handling of the train protection. As described in 2.1.2 (2), the concerned conductor stated that he implemented the indication of the stop signal by the alarm signal of the train protection radio device, after that, he

55 Translated by T. A. Lab., Inc., Japan, Sept., 2019

reported to the train dispatcher, looked for the concerned driver, implemented the rescue activity for the injured persons, etc.

2.10.7. Status of the Operation Suspension by the Train Dispatcher As described in 2.1.4 (1), the train dispatcher stated that he received the telephone from the concerned conductor, at about 19:16, that the concerned conductor sent the alarm signal by the train protection radio device. Then, he suspended the operation of the related trains immediately.

2.10.8. Status of the Opposite 831D Train As described in 2.1.5 (5), the opposite 831D train had been stopped at Amarume station when the accident occurred. The driver and the conductor of the opposite 831D train stated that they received the alarm signal by the train protection radio device while the train had been stopped at Amarume station. In addition, the driver of the opposite 831D train stated that he received the communication on the operation suspension from the train dispatcher while waiting at Amarume station.

2.10.9. Status of the Following Train As described in 2.1.5 (4), the following train had been stopped at Higashi-Sakata station when the accident occurred. The driver and the conductor of the following train stated that they received the alarm signal by the train protection radio device before closing the passenger door after arrived at Higashi-Sakata station. In addition, the driver of the following train stated that he received the alarm signal at about 19:15.

2.10.10. Outline of the Measure for Preventing Wheel Rolling The measure for preventing wheel rolling is the measure to prevent movement of the train or the vehicle while the driver left from the driving cab. The measure for preventing wheel rolling should be implemented using the hand brake, the chock etc., in the situation that the driver could not return to the driving cab immediately when the driver implements the handling train protection by the portable fuse and the rail clamp shunt or the parking procedure of the vehicles, even when the driver is in the status to be able to watch the train or the vehicle always.

2.10.11. Handling on Measure for Preventing Wheel Rolling The "Business Standard of Train Driver" of the Company prescribed on the measure for preventing wheel rolling as follows. 4. Train Operation [When the driver leaves from the driving cab] No.18. The driver is not allowed to leave the driving cab while being engaged in train operation. However, when the driver leave the driving cab reluctantly, the driver should have to implement the required measures such as the measure for preventing wheel rolling

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etc., and make effort to report to the dispatcher, etc. In addition, the "Manual of Handling Operation in Abnormal Condition, driver edition" prescribed as follows. 1. When an accident had happened or when felt an abnormal or dangerous situation - Accident occurred

Find obstacles

Sound an emergency whistle

Apply the emergency brake

Lower pantographs or stop engine if required Apply the one touch operative emergency brake Send alarm of train protection radio

Ignite the fuse for vehicles

Confirm existence of hindrance in the neighboring track

Ignite the portable fuse

Set the rail clamp shunt

Apply the preventing wheel rolling

Comprehension of the situation

Communicate to dispatcher

2.10.12. Contents of the Company's Education on the Measure for Preventing Wheel Rolling According to the Company, the required measures such as the measure for preventing wheel rolling etc., are the attachment of the chocks, firmly fastening of the hand brake, and the removal of the master controller key or the brake valve handle, and should be implemented when it is required to leave the driving cab for a long time due to park the vehicles or to implement the underfloor inspection of the vehicles, etc. In addition, as "ignite the portable fuse", "Set the rail clamp shunt", "apply the preventing wheel rolling" are written in this order in the flow chart in the "Manual of Handling Operation in Abnormal Condition, Driver edition" described in 2.10.11, the Company instructed in the training education that the driver is allowed to change these order in the actual operation based on judgment by the driver corresponding the status of the occurrence of accident etc.

2.10.13. Handling of the Measure for Preventing Wheel Rolling by the Concerned Driver As described in 2.1.2 (1), the concerned driver stated that he judged as the measure for preventing wheel rolling for the 6th vehicle was not needed based on the derailed status. In addition, according to the Company, the immediate measure of preventing wheel rolling

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was not needed as there was no fear of rolling wheels because the 6th vehicle had been stopped in the status that an axle in the 6th vehicle had been derailed and coupled with the 5th vehicle which was derailed.

2.11. The past railway accidents etc., caused by strong wind 2.11.1. Train Derailment Accident in Tozai Line of the Teito Rapid Transit Authority At about 21:34 on February 28, 1978, the train, running at about 78 km/h on the Arakawa Bridge between Minami-Sunamachi station and Kasai station of Tozai Line, was stirred by the gust of wind. Among the total 10 vehicle trainset, the rear three vehicles, the 5000 series vehicle of the tare about 36 ton, the 5200 series vehicle of the tare about 36 ton, the 5600 series vehicle of the tare about 35 ton, were derailed. Among three vehicles, two vehicles, the 5000 series and the 5200 series vehicles, overturned and the 20 passengers and a crew were injured. The Teito Rapid Transit Authority established the "Research Meeting to Measure the Train Disaster Accident in Tozai Line" and implemented the investigation on the causes of the accident. The investigation estimated that the accident occurred in extremely short time as the vehicles and the railway facilities were in normal situation, because there was no factor to cause the accident in the vehicles, tracks, etc., and there was only one trace considered as caused by the flange of the wheel on the top surface of rail, and only a few damages due to wheels on the sleepers in spite of overturning two vehicles in the train, and the overturned vehicles fell in the different ways each other, etc. Here, the time from being hit by the wind to stopped after overturned was estimated about 3.5 s to 4.5 s, for the 2nd vehicle from rear end of the train, i.e., front vehicle in the two overturned vehicles, in the investigation report. In addition, as the wind direction and the wind speed at the occurrence of the accident were not determined, the investigation report concluded that the accident was caused by the gust of wind originated in the tornado, because the damages as the collapsed houses, blown roofs etc., due to the gust of wind were found in the belt shaped area from Kawasaki City of Kanagawa Prefecture to Kamagaya City of Chiba Prefecture, and these damages occurred in the belt shaped area within a short time, the anemometer in the Tokyo Bay No.10 wharf, existed in these belt shaped damaged area, recorded the instantaneous wind speed of 52 m/s, and the wind direction dynamically changed within several 10 seconds, and the area of the strong echo spread in hook-shape, which is sometimes observed when the tornado had occurred, was observed at 21:50, i.e., after the occurrence of the accident. Here, the wind speed averaged for 10 minutes recorded in the anemometer, located about 800 m west from the accident site and installed by the Teito Rapid Transit Authority, was 2 m/s, which was not the strong wind. However, the anemometer in the Sunamachi water gate, located at about 2 km SW from the accident site, recorded the instantaneous wind speed of 43 m/s.

2.11.2. Train Derailment Accident in San-in Line of the Japanese National Railways At about 13:25 on December 28, 1986, the deadheading passenger train, running at about 55 km/h on Amarube Bridge between Yoroi station and Amarube station of San-in Line, was stirred

58 Translated by T. A. Lab., Inc., Japan, Sept., 2019 by the strong wind. Among the 8 vehicles train set, composed of an internal combustion locomotive and 7 coaches, the rear 7 coaches fell from the bridge and 4 train crews etc., and 8 publics were dead or injured. Here, the 7 coaches were composed of two Su-Ro-Fu 14 series vehicles of the tare about 37 ton per vehicle and five O-Ro 14 series vehicles of the tare about 29 ton per vehicle. When the accident occurred, the anemometer located on mountain side of the 7th pier of Amarube Bridge recorded that the wind speed increased from about 13:00, and the maximum instantaneous wind speed until to the accident was 33 m/s. Here, at the time of the accident, there were 2 anemometers installed in Amarube Bridge but the anemometer located in seaside of the 3rd pier had been in trouble. It was prescribed that the train should be stopped if the instantaneous wind speed exceeds 25 m/s, but this prescription was not applied. On the accident day, the strong wind accompanied with the gust was observed in the seaside of Japanese Sea from Chugoku district to Hokuriku district, according to the movement of the low pressure stayed in southern Japanese Sea toward east, and the damages as the fallen off steel pedestrian bridge etc. had occurred in around the Amarube bridge. The Japanese National Railways established the Meeting of Technology Investigation on the Amarube Accident, and implemented investigation on the causes of the accident etc. As the result of the investigation, the wind direction at the time of the accident was estimated as NNW to N, close to the right angle for the vehicles in high possibility, based on the wind tunnel test using the topographical model and the wind directions on the sea close to the Amarube Bridge. In addition, the wind speed at the time of the accident in the seaside of the 3rd pier of the Amarube Bridge, where the wind speed was supposed as strong due to the effects of the topographical features, was estimated as strong as about 40 m/s by the analysis based on the records of the wind speed in mountain side of the 7th pier. On the other hand, the instantaneous wind speed of about 35 to 45 m/s were obtained as possible in around the Amarube Bridge at the time of the accident, in the estimation based on the statistical data of the weather observation related authorities in around the accident site. The critical wind speed of overturning for the vehicle was calculated by using the aerodynamic force coefficient obtained in the measuring test of aerodynamic force implemented measurement of the aerodynamic forces by the wind tunnel test using the vehicle models. As the result, the critical wind speed of overturning for the intermediate vehicle in the overturned three vehicles was about 32 m/s. Based on these results, the cause of the accident was estimated that the vehicles derailed and overturned being acted by the strong wind exceeded the critical wind speed of overturning. The meeting proposed the following measures against strong wind responding to the occurrence of the accident. - Install the anemometers in the optimum places such as considering the place where the wind speed becomes to the maximum. - Consider the measures to stop the train promptly such as to interlink the obstruction warning signal and the anemometer, etc.

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2.11.3. Train Derailment Accident in Nemuro Line of the Hokkaido Railway Company. At about 17:45 on February 22, 1994, the express train, composed of 7 internal combustion railcars, running in the velocity from 50 km/h to 80 km/h was stirred up by strong wind in the curved track section of 500 m radius on the embankment in around Hirouchi Bridge between Nishi-Shintoku signal station and Hirouchi signal statin of Nemuro Line. Among the 7 vehicles, front 3 vehicles, i.e., Ki-Ha 183 series 500s vehicle of the tare about 41 ton, Ki-Ha 184 series 0s vehicle of the tare about 44 ton, and Ki-Ha 183 series 0s vehicle of the tare about 46 ton, derailed to left of running direction, and 27 passengers and a train crew were injured. The strong wind blew in each area in Hokkaido, as the low pressure grew terribly in off Nemuro, and the Nemuro Observatory observed the atmospheric pressure 948.7 hPa, on the accident day. The instantaneous wind speed 28.2 m/s was recorded in Shintoku Livestock Experimental Station of Hokkaido Government, about 2 km north from the accident site, at 17:44, about the same time of the occurrence of the accident. Hokkaido Railway Company implemented the investigation and estimated that the vehicles running on the embankment were derailed by being hit by the wind strong as exceeded the critical wind speed of overturning from right of the running direction, based on the data recorded in the anemometer of Shintoku Livestock Experimental Station of Hokkaido Government etc., and the results of the wind tunnel test. The investigation report proposed the following measures against strong wind. - Maintain the devices in the status that the functions, such as anemometers, wind speed detection and the alarm device, work well. - Increase the critical wind speed of overturning by reducing the aerodynamic force acting on the vehicles by installing the windbreak fences and the windbreak forest. Here, the electric wire in the anemometer was broken at the time of the accident but this information was not noticed to the CTC center. In addition, Hokkaido Railway Company implemented the measures such as the installation of the windbreak fence etc., in the section in around the accident site.

2.11.4. Train Derailment Accident in South Rias Line of the Sanriku Railway Co. Ltd. At about 15:22 on February 22, 1994, the train, composed of 2 internal combustion railcars, running at about 28 km/h on Yahagigawa Bridge and the embankment, in the section from circular section to transition curve section, between Koishihama station and Horei station of South Rias Line, were stirred by strong wind. All two vehicles, i.e., the 36 series vehicles of the tare was about 32 ton per vehicle, derailed to right of the running direction and overturned, and 5 passengers were injured. The strong wind blew in Tohoku district on the accident day, as the low pressure grew terribly in off Nemuro, and the atmospheric pressure 948.7 hPa was observed in Nemuro Observatory. The instantaneous wind speed exceeding 30 m/s had been recorded in each place in Sanriku seaside in Iwate Prefecture, before and after the occurrence of the accident.

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Sanriku Railway Company implemented the investigation on the causes of the accident. In the investigation, to estimate the wind speed in around the accident site at the time of the accident, the measurement of the wind speed was implemented and investigated the relationships with the existing wind speed measuring points in around the accident site, but the wind speed could not be estimated. In addition, the wind direction was estimated as in the 80 to 105 degrees, i.e., close to the right angle, against the running direction of the train, based on the distribution of the wind direction in around the accident site. The critical wind speed of overturning for the vehicle was estimated as about 35 to 37 m/s, when the effects by the embankment was not considered, by the calculation using the aerodynamic force coefficient obtained from the aerodynamic force measurement test implemented using the wind tunnel with the vehicle models. Based on these results, the causes of the accident were estimated that the vehicles overturned as being acted by the strong wind exceeded the critical wind speed of overturning from left of the running direction while the vehicles were running on the embankment. Here, Sanriku Railway Company had implemented the measures such as the installation of the windbreak fence in the accident site after the accident.

2.11.5. Train Derailment Accident in Kosei Line of the Japan Freight Railway Company At about 00:00 on June 29, 1997, the freight train, composed of an electric locomotive and 20 container wagons, halting in the premises of Hira station of Kosei Line was stirred up by strong wind and 3 container wagons, the 3rd to the 5th vehicles from the rear end of the 21 vehicles train set, derailed but no one was injured. Here, all derailed wagons were Ko-Ki 50000 type wagon of the tare was about 18 ton per wagon, the 3rd vehicle from the rear was loaded with five empty containers, the 4th vehicle from the rear was loaded with an empty container and four loaded containers, the 5th vehicle from the rear was loaded with five empty containers. Here, as the maximum wind speed 25 m/s was recorded in Houraigawa anemometer etc., at 22:30 on June 28, the operation of the concerned train was suspended in approach of the down line No.2 block signal in the premises of Hira station at 22:32. The recorded wind speeds in the accident site at the time of the accident were 43 m/s at about 23:45 on June 28, and 39 m/s at about 0:00 on June 29. Japan Freight Railway Company implemented the investigation and estimated the causes of the accident as that the vehicles derailed due to the wind speed in the accident site at the occurrence of the accident had exceeded the critical wind speed of overturning for the container wagons.

2.11.6. Train Derailment Accident in Chikuhi Line of the Kyushu Railway Company At about 19:11 on March 19, 1998, the train composed of 6 electric railcars, running at about 60 km/h on the low embankment constructed in flat field in Imajuku station of Chikuhi Line, was stirred by strong wind and the front vehicle, the 103 series 1500s vehicle of the tare about 31 ton, had derailed to left of the running direction, and 3 passengers were injured.

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The low pressure was growing in Japanese Sea on the accident day, and the strong wind had been blown intermittently from 19:00 to about 23:00 on the same day in northern area of Kyushu district, accompanied with the growing low pressure and the movement of the cold front toward south. The anemometer installed at a height of 25.5 m from the ground of the steel tower of Kyushu Electric Company, located at about 550 m distant from the accident site, recorded the instantaneous wind speed 45.1 m/s at 18:52. Kyushu Railway Company implemented the investigation on the wind direction and the instantaneous wind speed at a height of 10 m from the ground at the accident site at the time of the accident, and estimated as about 30 to 35 m/s from SSE to S. As there was the over bridge between the place where the derailed trace was found on the track and the place where the vehicles stopped after derailed, the scale model of the accident site including the over bridge was manufactured and used in the wind tunnel test. Then, the critical wind speed of overturning was calculated based on the aerodynamic force measured in the wind tunnel test. As the results, it was identified that the wind speed in the position of the track increased for a certain wind direction due to the existence of the over bridge, and the critical wind speed of overturning for the vehicle running at 55 to 60 km/h was about 34 m/s when considered the effects by the over bridge. Based on these results, the cause of the accident was estimated as that the vehicle derailed by being acted by the strong wind exceeded the critical wind speed of overturning from right of the running direction, while the vehicle was running on the embankment.

2.11.7. The Windbreak Fences etc., of the Company The Company had installed the windbreak fences etc., in the following four areas before the occurrence of the accident. The all four areas were the earlier control section before the windbreak fences were installed but revised to the normal control section after installed the windbreak fences.

2.11.7.1 Windbreak fence in the premises of Nebukawa station of Tokaido Line The windbreak fence in the premises of Nebukawa station of Tokaido Line was installed in both side of the track in around Shiraitogawa Bridge at a height of 3 m from rail surface for 400 m in length and completed on July 1991.

2.11.7.2. Windbreak fence between Yonomori station and Ohno statin of Joban Line The windbreak fence between Yonomori station and Ohno statin of Joban Line was installed in the west side of the track in around Kumakawa Bridge for total 480 m distance, heights of the fence were 3 m from the rail surface in the bridge section and 2 m from the rail surface in the embankment section, and completed on February 1996.

2.11.7.3. Windbreak fence between Sashiogi station and Minami-Furuya station of Kagawoe Line The windbreak fence between Sashiogi station and Minami-Furuya station of Kagawoe Line was installed in north side of the track in around Arakawa Bridge for total 791 m long, its

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height was 2 m from the rail surface, and completed on April 1998.

2.11.7.4. Windbreak fence between Nobiru statin and Rikuzen-Ono station of Senseki Line The windbreak fence between Nobiru statin and Rikuzen-Ono station of Senseki Line was installed in the north side of the track in around Narusegawa Bridge for total 1,126 m long, its height was 1.8 m from the rail surface, and completed on June 2000.

2.12. Experiments etc., to Determine the Facts 2.12.1. Investigation and Analysis of the Wind Speed etc. The observation of the wind direction and the wind speed were implemented by installing the new anemometers, hereinafter referred to as "the added anemometer", in around the existing anemometer and the accident site after the accident, to comprehend the characteristics of the natural wind in around the accident site and to obtain the required values to recreate the atmospheric currents to be used in the measuring test of the aerodynamic forces, i.e., lateral and lift forces, ant the rolling moment, hereinafter referred to as "the aerodynamic forces etc.", to calculate the critical wind speed of overturning described in 2.12.2.

2.12.1.1. Observation of wind direction and wind speed [Refer to Attached Figures 34, 35] The windmill type wind vane and anemometer*34 was used as the added anemometers. The observing points were set in the observation tower between the up and down tracks in around the accident site, hereinafter referred to as "the observation tower A", the observation tower in west of the toe of slope of the embankment in around the accident site, hereinafter referred to as "the observation tower B", the observation tower between the up and down tracks in 10 m backward of the observation tower A, hereinafter referred to as "the observation tower C", and around the position of the existing anemometer. The located places, symbols corresponded with the location of anemometers, installed height, and observed periods were as shown in Table 13. *34 "Windmill type wind vane and anemometer" is one of the wind vane and anemometer. The streamlined cylinder, equipped by propellers with about 4 vanes on its tip, i.e., windmill, and the vertical empennage in its rear, was attached to the column as to be rotating freely in the horizontal plane. By setting as the windmill always directs to the windward, the wind speed and the wind direction are measured by the rotating speed of the windmill and direction of the cylinder, respectively.

Table 13. Located places of the wind vane and anemometers Located places of anemoscope and anemometer Symbol Height from Observed period rail surface A1 15.2 m Around the Observation tower A, between A2 10 m From January 22, accident 158,180 m up and down tracks to June 30, 2008 site A3 5 m A4 2.5 m

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B1 15.2 m From January 22, Observation tower B, west of B2 10.15 m 2006 to January toe of slope of embankment B3 5 m 31, 2007 B4 0 m

Observation tower C, between C1 5 m From January 22, 158,190 m up and down tracks C2 2.5 m to June 30, 2006 Around the 158,995 m Between up and down tracks K1 5 m From January 6, existing to June 30, 2006 anemometer 159,005 m Between up and down tracks K2 5 m Ref. Existing 159,000 m Between up and down tracks 5 m anemometer

2.12.1.2. Logging and classifying of the data As for the observed wind direction and the wind speed, the instantaneous wind speed and instantaneous wind direction were defined by the recorded values obtained by sampling for 1 second. Here, the abnormal data considered as caused by the physical or electrical troubles from the remarkable increase or decrease on the wind speed in 1 second etc., were omitted. The analysis was implemented by using the instantaneous values and the values averaged for 1 minute or 10 minutes.

2.12.1.3. Comparison of the existing anemometer and the added anemometer The existing anemometer installed in Akita station side of the concerned bridge was the wind cup type anemometer. As there is the case that the wind cup type anemometer did not output the observed data when the wind is weak, the windmill type wind vane and anemometers, generally used in the JMA etc., were installed as the added anemometers, and the difference caused by the different measuring devices were analyzed using the observed data in the 5 strong wind days from January 6 to March 31, 2006. The maximum value in 3 minutes in the existing anemometer was compared to the values in the added anemometers K1, K2 and K3, installed in around the existing anemometer. As the results, the average wind speed difference was 0.23 m/s and the standard deviation of the wind speed difference was 1.71 m/s. Among these values, the average wind speed difference was 0.01 m/s and the standard deviation of the wind speed difference was 1.45 m/s for the observed data obtained when the maximum values in 3 minutes measured in the anemometers K1 and K2 had exceeded 20 m/s. The result that the difference of the measured values in these anemometers were within about 3 m/s, therefore, it was verified that the difference in the output data of the existing anemometer and the output data of the anemometers K1 and K2 was small.

2.12.1.4. Characteristics of the natural wind in around the accident site The maximum wind speed observed in the observed period in the added anemometers A1 and B1, located in the highest positions installed in the observation towers A and B,

64 Translated by T. A. Lab., Inc., Japan, Sept., 2019 respectively, and the added anemometer A3 located at a height of 5 m which was the same height from the rail surface as the existing anemometer, were as shown in Table 14.

Table 14. Maximum wind speed in the observed period Maximum values in the observed period Equipped height from rail surface Instantaneous wind speed Average wind speed in 10 minutes Anemometer A1 27.8 m/s, March 29, 2006 18.7 m/s, April 3, 2006 15.2 m Anemometer B1 34.5 m/s, January 7, 2007 19.9 m/s, January 7, 2007 5 m Anemometer A3 27.7 m/s, March 20, 2006 17.3 m/s, April 3, 2006 * The maximum instantaneous wind speed observed in the existing anemometer on the accident day was 21 m/s.

The characteristics of the wind in around the accident site were clarified as follows based on the observed results in the observation tower B, including the strong wind as shown in Table 14, for about 1 year, from January 22, 2006 to January 31,2007. Here, the status when the instantaneous wind speed of above 15 m/s was observed in the anemometer B1 is called as "the strong wind status". (1) The occurrence frequency distribution of the wind direction through a year was almost the same as that in Sakata Observatory. (2) The strong wind statuses mainly occurred in February and March. (3) The many wind directions in the strong wind status were WNW or NW. On the other hand, the ratio of the wind direction of ESE or SE were large from April to October, as the number of the emergence was small compared to that in the winter. (4) The gust factor*35 and the intensity of turbulence*36 in the added anemometers installed in the observation towers A and B, in the strong wind status by the wind from west in the period from January to June, were as shown in Table 15.

Table 15. The gust factor and intensity of turbulence in the strong wind from the west When the average wind direction of the anemometer B1 was in the range S-W-N, as being the wind blew from west of the embankment. Equipped height from rail surface Gust factor Intensity of turbulence Anemometer A1 1.432 0.154 15.2 m Anemometer B1 1.447 0.159 Anemometer A2 1.455 0.161 10 m or 10.15 m Anemometer B2 1.467 0.163 Anemometer A3 1.503 0.175 5 m Anemometer B3 1.494 0.168 2.5 m Anemometer A4 1.578 0.195 0 m Anemometer B4 1.546 0.180

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Here, the number of total data used in Table 15 were 1,506 cases occurred from January 22, 2006 to June 30, 2006. *35 "Gust factor" in this context, was defined as the ratio of the maximum instantaneous wind speed averaged for 10 minutes to the wind speed averaged for 10 minutes. The factor expresses the magnitude of the maximum instantaneous wind speed compared to the average wind speed in the same time range and considered as a standard of the characteristics of the natural wind. The gust factor is in the level of 1.5 to 2, in general. *36 "Intensity of turbulence" in this text is the ratio of the deviation of the instantaneous wind speed to the average wind speed. This ratio was set as the standard of the characteristics of the natural wind indicated the deviating component of the wind speed.

2.12.1.5. Effects of the embankment to the wind speed When the average wind directions in the strong wind status obtained from the anemometer B1 were in the range of S-W-N, which correspond to the wind from west at the embankment, investigation was implemented on the effects by the existence of embankment by comparing the outputs of the added anemometers installed in the same height from the rail surface in the output of the added anemometers in the observation towers A and B. The results were shown in Table 16. In addition, the ratio of the wind speed obtained from the anemometer B4 to the wind speeds obtained from the other added anemometers were investigated and results were as shown in Table 17.

Table 16. Wind speed ratio in the status of the strong wind Comparison of the added anemometers equipped at the same height from rail surface Wind speed ratio of the added anemometers in observation towers A and B Equipped height [Observation tower A/Observation tower B, averaged the results of all cases] from rail surface Maximum instantaneous wind Maximum instantaneous wind speed speed for 1 minute for 10 minutes 15.2 m 1.06 [A1/B1] 1.07 [A1/B1] 10 m or 10.15 m 1.08 [A2/B2] 1.09 [A2/B2] 5 m 1.07 [A3/B3] 1.08 [A3/B3]

Table 17. Wind speed ratio in the status of the strong wind Ratio of the wind speed in the anemometer B4 and the wind speed in the other added anemometers Wind speed ratio against the anemometer B4, averaged the results of all Equipped height cases on the maximum instantaneous wind speed for 1 minute. from rail surface Anemometer in observation tower A Anemometer in observation tower B 15.2 m 1.27 [A1/B4] 1.20 [B1/B4] 10 m or 10.15 m 1.22 [A2/B4] 1.13 [B2/B4] 5 m 1.16 [A3/B4] 1.09 [B3/B4] 2.5 m 1.12 [A4/B4] 0 m 1.00 [B4/B4] : Reference anemometer

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Here, the total numbers of the data used for calculation of the wind speed ratio were 6,730 cases for the maximum instantaneous wind speed for 1 minute, and 1,506 cases for the maximum instantaneous wind speed for 10 minutes.

2.12.1.6. Comparison of the wind speed in around the accident site and in around the existing anemometer To investigate the correlation between the wind speeds in around the accident site and in around the existing anemometer, the observed results of the anemometers A3 and K2 were compared. The maximum instantaneous wind speeds for 1 minute were calculated for each anemometer and compared. As the results, the average value of the wind speed differences was 0.16 m/s, and the standard deviation was 1.50 m/s. In addition, the instantaneous wind speed which satisfied all of the following conditions and their trends were compared. (1) The maximum instantaneous wind speed for 10 minutes had exceeded 20 m/s in one of the anemometers A3 and K2. (2) One of the wind directions averaged for 10 minutes of one of the anemometers in the above (1) was in the range of S-W-N. In addition to the 10 minutes corresponded with the above conditions, the observed results in before 30 minute and after 30 minutes were picked up and compared the wind speed differences of the instantaneous wind speed. The results showed that the frequency that the instantaneous wind speed in the anemometer A3 exceeded that in the anemometer K2 over 4 m/s, was 4.8 %.

2.12.2. Calculation of the Critical Wind Speed of Overturning The measurement of the aerodynamic forces acting on the model vehicles and the wind speed in around the embankment, and the calculation of the critical wind speed of overturning of the vehicle were implemented by recreating the aerodynamic currents simulated the natural wind in around the accident site and implemented the wind tunnel tests using the scale models of the ground structures and the accident vehicles.

2.12.2.1. Outline of the tests (1) Equipments for the wind tunnel test The airtight low noise large scale wind tunnel was used. The dimensions of the measuring part were 3 m high, 5 m wide and 20 m long. The measurement was implemented by setting the models on the turn table. [Refer to Attached Figure 36] (2) The scale model for the wind tunnel test The models of the vehicle and the ground facilities such as the embankment etc., were made in a scale of 1:40. The train model was composed of 6 vehicles. The devices which can measure the aerodynamic forces etc., acting on the vehicles, i.e., the six-component balance, were fixed to the 1st and the 2nd vehicle models. The ground facilities were modeled by the embankment for the double track cross section at 158,180 km point of Uetsu Line in around

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the accident site. [Refer to Attached Figures 37, 38] (3) The wind used in the test The device creating the turbulent flow boundary layer was equipped in the wind tunnel and simulated the characteristics of the natural wind in around the accident site, in the wind tunnel test. The wind speed measured at the position, 5 m to windward from the turntable, 1.8 m above the floor and 1.504 m left from the center of the width of the wind tunnel, where the measured wind speed was hard to be affected by the models and the measuring devices in windward from the measuring place, was treated as the test wind speed, i.e., the control wind speed, in the wind tunnel test. The measurements of the wind speed in the wind tunnel test were implemented at the position corresponded to each measuring point in the observation tower A, hereinafter referred to as "the measuring line A", the position corresponded to each measuring point in the observation tower B, hereinafter referred to as "the measuring line B", and the position in the center of the up track at the same height as in the measuring line A, hereinafter referred to as "the measuring line D". The characteristics of the wind speed in the wind tunnel test was adjusted by the device creating the turbulent flow boundary layer so that the power index*37 was 1/7, the intensity of turbulence was 0.15, based on the measured results of the wind speed in around the accident site described in 2.12.1. As the results, the indices to express the wind speed distribution due to the difference of the height in the vertical direction in the measuring line B was 1/6.9 to 1/7.25, the intensity of turbulence was 0.16 to 0.17, which were almost the prescribed condition. Here, the test wind speeds, i.e., control wind speed, were set in three levels, i.e., 20, 25, 30 m/s, which correspond to the Reynolds numbers*38 when the height of the vehicle body was set as the represented length were 1.03×105, 1.29×105, 1.55×105, respectively, and the wind direction angle against the vehicles β were set from 30° to 105° by every 15°, as the wind direction from the running direction was set as 0° and the wind from lateral direction in right angle was set as 90°. [Refer to Attached Figures 39, 40, 41, 42] *37 Generally, it was known that the wind speed u at the height of Z, near the ground surface, was n distributed as expressed by u = u 0 (Z Z 0 ) , where, Z0 is the reference height and u0 is the wind speed in the standard height. The "n" in the equation was called as the "power index", and the value depends on the status of the ground surface. *38 "Reynolds number" is the nondimensional number defined as the ratio of the inertial force to the

viscous force, and expressed by Re = u A L v , here, uA is the representative speed, L is the representative length, and v is the dynamic viscosity or the dynamic viscous coefficient.

2.12.2.2. Measured results of wind speed in around the ground facilities, i.e., the embankment The wind speed was measured in the status that the ground facility model, i.e., the embankment, was set in the wind tunnel. As the result, it was observed that the wind speeds in the measuring line A were in the trend to be faster than the values measured in the measuring line B. The average wind speed, in the points corresponded to the position at a height of 5 m from

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the rail surface in the actual measuring lines A and B, were measured and compared by blowing the lateral wind from the direction of the right angle against the track. The results showed that the the average wind speed in the measuring point corresponding the anemometer A3, hereinafter referred to as "the measuring point A3", was about 1.13 times of the average wind speed in the measuring point corresponding the anemometer B3, hereinafter referred to as "the measuring point B3".

2.12.2.3. Measurement of the aerodynamic forces and the rolling moment The aerodynamic forces etc., acting on the vehicles, i.e., the 1st vehicle and the 2nd vehicle, being exposed to the wind were measured by changed the intensity and the direction of the wind as described in 2.12.2.1 (3), using the scale models for the wind tunnel test described in 2.12.2.1 (2). The lateral force factor, the lift force factor and the moment factor showing the relationships between the wind speed and the acting aerodynamic forces etc., hereinafter referred to as "the aerodynamic force factor etc.", were calculated from these measured aerodynamic forces etc., and used them in the calculation of the critical wind speed of overturning described in 2.12.2.4. [Refer to Attached Figure 43] Here, the aerodynamic force factor etc., were the indices expressed the relationship between the square of the wind speed and each aerodynamic force etc. and expressed as follows.

F F : Lateral force Lateral force factor C = s S s 1 2 2 U S FL : Lift force M : Rolling moment FL Lift force factor C = 3 L 1 2 ρ : Air density = 1.23 kg/m 2 U S U : Reference wind speed M Moment factor C = hB : Height of vehicle body M 1 U 2 Sh 2 B S：: Ares of side surface of the vehicle body The three levels of the test wind speed, i.e., the control wind speed, i.e., 20, 25, 30 m/s, were set in the wind tunnel test, but the measured result in 30 m/s was used to calculate the critical wind speed of overturning as the dependency of the aerodynamic forces etc., to the wind speed was small, because it was clarified that the difference in the aerodynamic force factors etc., due to the difference of the control wind speed was small. The aerodynamic force factors etc., of the 1st and the 2nd vehicles obtained from the wind tunnel test were as shown in Table 18, here, the average wind speed in the measuring point A3 was considered as the reference wind speed. The lateral force factors became to the maximum values when the wind direction angle against the train direction β was 60° for the 1st vehicle, and 75° for the 2nd vehicle.

Table 18 Aerodynamic force coefficient etc., of the 1st and the 2nd vehicles The 1st vehicle The 2nd vehicle Angle of wind direction β [deg] Side force Lift force Moment Side force Lift force Moment coefficient coefficient coefficient coefficient coefficient coefficient

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Cs CL CM Cs CL CM 30 0.69 0.42 -0.09 0.48 0.33 -0.07 45 0.95 0.55 -0.11 0.69 0.49 -0.08 60 1.07 0.60 -0.12 0.87 0.60 -0.10 75 1.03 0.57 -0.11 0.93 0.62 -0.10 90 0.89 0.55 -0.09 0.83 0.54 -0.09 105 0.71 0.48 -0.07 0.75 0.49 -0.08 [Refer to Attached Figure 44]

2.12.2.4. Calculation of the critical wind speed of overturning The critical wind speed of overturning for the train was calculated by the static analysis using the static balance equations considering the wind pressure and the lateral force of inertia, using the aerodynamic force factors etc., obtained from the wind tunnel test described in 2.12.2.3. Here, in the calculation, the half vehicle model considering the displacement of the vehicle body due to the spring system etc., of the vehicle was used, and calculated the wind speed corresponding to the observed value at a height of 5 m from the rail surface which was the same as the installed height of the existing anemometer, considering the effects by the running velocity of the train, wind direction, etc. (1) Method of the calculation The track was assumed as straight and the effects by the centrifugal acceleration were not

considered, in the calculation. The acceleration of the lateral vibration of the vehicle body αy [m/s2] was calculated by the following equation, referring the results of the running test using the commercial vehicles implemented in the past in Japan.

αy = 0.98 v/vmax

here, v [m/s] is the running velocity, vmax [m/s] is the maximum velocity of the train. Here, the above equation means that the acceleration of the lateral vibration of 0.1 G, i.e., 0.98 m/s2 which is 10% of the gravitational acceleration, is acted to the vehicle when the concerned train is running in the maximum velocity 120 km/h. Here, the calculation was also implemented for the case that the acceleration of the lateral

vibration of the vehicle was set as αy = 0.49 v/vmax and αy = 0, for the comparison. The model for calculating the critical wind speed of overturning was shown in the Attached Figure 45, and the model of the spring system of the vehicle used for estimating the displacement of the gravity center of the vehicle body was shown in the Attached Figure 46. In the Attached Figure 45, the equation to express the balance of the moment around the lee side contact point of wheel and rail when the rolling deviation of the gravity center of the

vehicle body φB could be considered as microscopic, was expressed as follows. Here, the

wheel load of the windward right wheel was expressed as PR. G  G   G  GPR = mT g + m B g  − y B  − FLA  − y B −e B  − hGB m B y − hBC FSA 2  2   2 

Here, G is the distance between the contacted points of wheel and rail, PR is the wheel load

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of right wheel, mT is the mass of the bogie, mB is the mass of the half vehicle body, yB is the

lateral displacement of the gravity center of the vehicle body, FLA is the lift force due to lateral wind, e is the distance between the center of the wind pressure and the gravity center of the

vehicle body, hGB is the height of the gravity center of the vehicle body, hBC is the height of

the center of the wind pressure, and FSA is the lateral force due to the lateral wind. The reduction ratio of wheel load D was expressed as follows, by rewriting the wheel load

of right wheel PR using the static wheel load P0 and the reduced wheel load ΔP.

(m B + mT )g P PR = P0 − P, P0 = ,  D 2 P0 The reduction ratio of wheel load D, obtained by solving the above equations, was expressed as follows.  1  y FSA FLA  G  D =  y B + hGB + hBC +  − y B − e B  G g m g m g 2 (1 + m m )  B B   2 T B

Here, the limit of overturning was considered as the wheel load of the windward wheel PR becomes to 0, i.e., D = 1, when the vehicle was hit by the strong wind. The wind speed when the wheel load of the windward wheel becomes to 0 can be obtained by the calculation, as the

aerodynamic forces acting on the vehicle FSA and FLA can be expressed by using the wind speed u. The wind speed is the relative wind speed for the vehicle as shown in Attached Figure 47, the wind speed vector of the natural wind w was calculated by the wind speed vector u and the velocity vector of the running train v, and determined as the critical wind speed of overturning for the wind direction α of the wind speed vector of the natural wind. The major specification of the vehicles used in the calculation were shown in Table 19.

Table 19. Specification of the vehicle used in the calculation of the critical wind speed of overturning Item Symbol Unit 1st vehicle 2nd vehicle

Mass of the half vehicle body mB kg 15,223 13,145

Mass of the bogie mT kg 5,650 7,380

Height of gravity center of vehicle body hGB m 1.67 1.67

Height of gravity center of bogie hGT m 0.50 0.50

Height of center of vehicle body hB1 m 2.24 2.24

Height of vehicle body hB m 2.47 2.47 2 Area of side surface of the half vehicle body SA m 25.6 24.7

Radius of the wheels RW m 0.425 0.410 Distance between contacted points of wheel and rail G m 1.12 1.12

Distance between centers of left & right axle springs 2b1 m 1.64 1.64

Distance between centers of left & right secondary suspensions 2b2 m 1.93 1.93

Distance between left & right vertical motion stoppers 2bS m 1.93 1.93

Height of center of the secondary suspension hKC m 0.777 0.777

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Height of the lateral motion stopper hSC m 0.543 0.543

Gap in the lateral motion stopper yS m 0.015 0.015

Gap in the vertical motion stopper zS m 0.022 0.022 5 5 Vertical spring constant of axle spring for each axle box k1 N/m 7.20×10 7.20×10 5 5 Vertical spring constant of each secondary suspension k2 N/m 3.71×10 3.26×10 5 5 Lateral spring constant of each secondary suspension kY N/m 2.19×10 1.92×10 6 6 Spring constant of a pair of lateral motion stoppers kYS N/m 2.42×10 2.42×10 7 7 Spring constant of a pair of vertical motion stoppers kZS N/m 1.41×10 1.41×10 4 4 Torsional rigidity of the torsion bar, the anti-rolling device. kR Nm/rad 3.14×10 3.14×10

The specification of the vehicles used in the calculation of the critical wind speed of overturning were based on the data provided by the Company, except for the height of the gravity center of the vehicle body and the mass of the vehicle body, which used the measured results for the similar vehicles of the same type remodeled as same as the vehicles in the concerned train described in 2.6.3. The calculation was implemented for the running velocity of the train from 0 to 120 km/h in every 5 km/h. (2) Results of the calculation The relationship between the wind direction angle of the natural wind α and the critical wind speed of overturning were as shown in Attached Figure 48-I and II, the relationship between the running velocity of the train and the critical wind speed of overturning were as shown in Attached Figure 49-I and II. As for the relation with the wind direction angle of the natural wind α, the critical wind speed of overturning becomes to the minimum when the wind blows from a little forward from the right angle, i.e., about 70° to 75°, and the critical wind speed of overturning was in the trend to decrease as the running velocity increases. The critical wind speed of overturning of the 1st and the 2nd vehicles were about 35 m/s and about 44 m/s, respectively, when the running velocity is 100 km/h, and about 32 km/h and about 41 km/h, respectively, when the running velocity is 120 km/h. The above calculation was implemented in case that the acceleration of the lateral vibration of the vehicle body was set as αy = 0.98 v/vmax.

When the acceleration of the lateral vibration of the vehicle body was set as αy = 0.49 v/vmax, the critical wind speed of overturning of the 1st and the 2nd vehicles were about 38 m/s and about 47 m/s, respectively, when the running velocity is 100 km/h, and about 35 km/h and about 45 km/h, respectively, when the running velocity is 120 km/h. In addition, when the acceleration of the lateral vibration of the vehicle body was set as αy = 0, the critical wind speed of overturning of the 1st and the 2nd vehicles, were about 41 m/s and about 49 m/s, respectively, when the running velocity is 100 km/h, and about 39 km/h and about 48 km/h, respectively, when the running velocity is 120 km/h. Here, when the wind direction angle of the natural wind α was changed about 20° from the wind direction angle 70° to 75° when the critical wind speed of overturning become to its

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minimum, the critical wind speed of overturning increased about 2 to 3 m/s.

2.12.3. Trial Calculation of the Critical Wind Speed of Overturning by Simple Equation The critical wind speed of overturning for the 1st and the 2nd vehicles of the concerned train were calculated by the following equation*39.

mgG 2h *   h   u =  D − G 1 −  GT  y c * G  1 +  *  g hBC  S ACY  hG 

* Here, hBC is the effective height of the center of the wind pressure and is 1.25 times of the height of the center of the wind pressure. G is the distant between the contact points of wheel and * rail. hG is the effective height of the gravity center of the vehicle and is 1.25 times of the height

of the gravity center of the vehicle. CY is the resistance factor of vehicle against the lateral wind,

here, CY = 1.00 when the wind had acted to the whole vehicle. μ is the ratio of the mass of the

vehicle body to the mass of the bogie, i.e., mT/mB. In this case, the acceleration of the lateral vibration of the vehicle body was set as 0.1 G = 0.98 m/s2, supposed the maximum operation velocity of the concerned train 120 km/h. Here, the above equation was well known as indicating the dynamic relationships on the overturning of the railway vehicles, but the effects by the velocity of running train and the wind direction etc., were not considered, different from the calculating method described in 2.12.2.4. Then, the critical wind speed of overturning was estimated by the above equation when the wheel load of the windward wheel was 0, when the wind had acted to the side surface of the vehicle from the direction in right angle. The specification of the vehicle used in the calculation were listed in Table 20. As for the each data of the specification of the vehicle etc., the same data used in the test to estimate the critical wind speed of overturning described in 2.12.2.3 and 2.12.2.4 (1), were used. The calculated results of the critical wind speed of overturning for the 1st and the 2nd vehicle were about 43 m/s and about 45 m/s, respectively. In addition, as described in 2.6.3, the vehicle in the concerned train had been remodeled but the height of the gravity center of the vehicle body had not been estimated after remodeled. Then, the effect by the height of the gravity center of the vehicle body to the critical wind speed of overturning was confirmed by the trial calculation. The results were that the critical wind speeds of overturning for the 1st and the 2ndvehicles becomes 0.6 m/s and 0.4 m/s smaller, respectively, when the height of the gravity center of the vehicle had increased by 10 cm. *39 M. Kunieda, "Dynamic theory analysis on overturning of railway vehicles", RTRI report, No.793, February 1972, in Japanese.

Table 20. Specification of critical wind speed of overturning for the concerned train by the simple equation Symbol 1st vehicle 2nd vehicle Dangerous ratio, reduction ratio of wheel load D 1 1

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Resistive coefficient of vehicle body against side C 1.00 1.00 wind, side wind coefficient. Y Mass of the half vehicle m 20,873 kg 20,525 kg Distance between contact points of wheel and rail G 1.12 m 1.12 m Density of air ρ 1.23 kg/m3 1.23 kg/m3 * Effective height of gravity center of the vehicle hG 1.69 m 1.56 m

Height of gravity center of the bogie hGT 0.50 m 0.50 m Mass ratio of vehicle body and bogie μ 0.371 0.561 * Effective height of center of the wind pressure hBC 2.80 m 2.80 m 2 2 Acceleration of lateral vibration of vehicle body αy 0.98 m/s 0.98 m/s 2 2 Area of side surface of half vehicle body SA 25.6 m 24.7 m

3. REASONS TO IDENTIFY THE FACTUAL INFORMATION

3.1. Analysis on the Railway Facilities 3.1.1. Analysis on the Causes of the Derailment It is probable that there was no abnormal situation in the railway structures and the track to cause the derailment, because the crews of the related trains stated that they did not feel the abnormal situation in the track in around the accident site before the occurrence of the accident, as described in 2.1.5 (2) and (3), and there was no abnormal situation in the inspected results for the railway structures and the track, as described in 2.5.8.

3.1.2. Analysis on the Traces in the Railway Facilities The results of the analysis on the traces confirmed in the damaged status in the track, the railway structures and the electrical facilities, described in 2.3.1 and 2.3.2, were described in the followings. (1) The traces in the section backward, toward Akita station, from the over-road bridge start edge There were the traces considered as caused by running wheels on the rail fastening devices and the sleepers, and the spring clips of the rail fastening devices were broken in crashed status, and the surfaces of the sleepers were broken and lacked, in the inside gauge of left rail in the forward section from the sleeper No.12b, as described in 2.3.1 (1). There were the hit traces in the corner of tread of left wheels in all 4 axles in the front and the rear bogies of the 2nd vehicle, all 2 axles in the rear bogie of the 3rd vehicle, and the 1st axle in the front bogie of the 4th vehicle, as described in 2.3.3.2 (6), 2.3.3.3 (7) and 2.3.3.4 (3). Therefore, it is probable that these traces were caused by being hit by around the tread corners of the dropped left wheels in some axles described in the previous text, considering the shapes of the traces in the rail fastening devices etc., and the shape of the wheels, and were not caused by the moving right wheels. It is probable that the damages and fallen away of the rail fastening devices in outside gauge of left rail and the traces on the sleepers in the forward track from the sleeper No.7b, were

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caused by the running of the derailed left wheels, because there was no trace considered as caused by the running wheels on the concrete blocks in the left of the over-road bridge start edge and on the gratings in left of the over-road bridge, as described in 2.3.1 (2). It is highly probable that the plural wheels had been derailed in the rear part of the over-road bridge and continue running, because there were the traces as caused by the plural running wheels on individual rail fastening devices in the both inside and outside gauge and sleepers. It is probable that the flaw from around the center of rail surface to the gauge corner on the left rail in around the sleepers No.16b to 15b, and the flaw on the rail surface of left rail almost parallel to the direction of train running in the forward section from the sleeper No.12b, were caused by the wheels based on the directions and the shapes of the flaws. It is highly probable that the pole No.V had tilted and the weight of the pulley type automatic tensioner had been collided with the upper part of the steady rest because the vehicle, derailed and had falling slope of the embankment, collided with the poles No.VI to No.IX and pulled the overhead contact line when the poles had folded and damaged, and not caused by the collision with the vehicles. (2) Traces in the section on the over-road bridge It is highly probable that the wheels had already been derailed in the section backward from the over-road bridge as described in (1), and there were the traces considered as caused by the running wheels in outside gauge of the left rail on the sleepers in the over-road bridge as described in 2.3.1 (2). Therefore, it is probable that a part of the sleepers in the over-road bridge were pushed out forward due to being hit by the derailed wheels. In addition, only the front side of the sleeper No.1 was damaged and lacked, and the sleeper No.2 was folded and severely damaged, but the characteristics of the traces in these sleepers was different from the traces on the other sleepers. Therefore, it is somewhat likely that these sleepers were damaged by the large impacts due to the fallen off left derailed wheels. It is probable that the traces in the sleepers, the rail fastening devices, the hook bolts ant L-shaped sleeper connectors were caused by the running left wheels, because there was no trace on the concrete blocks and the gratings in left of the over-road bridge start edge, and there were the traces on the concrete blocks in left of the over-road bridge end edge as described in 2.3.1 (2). The traces found on the rail fastening devices in outside gauge of left rail on the over-road bridge continued in backward section from the sleeper No.13, however, there was no trace on the sleepers No.14 to No.18, and there were traces in outside gauge of left rail on all sleepers in the over-road bridge, furthermore, there were the traces on the concrete blocks in left of the over-road bridge end edge. Therefore, it is probable that the left wheels that had damaged the rail fastening devices in the backward section from the sleeper No.13 had moved to left still more in the forward section from the sleeper No.14. The traces on the rail fastening devices in inside gauge of left rail, which were continued to around the sleeper No.19, was not existed in the forward section, but the rail fastening devices in outside gauge of left rail on the sleepers No.19 to No.21 were damaged. Therefore, it is

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probable that the plural wheels, that had been derailed to inside gauge, climbed over the left rail in around here and moved to outside gauge of left rail. In addition, there were the traces considered as caused by the plural running wheels on the sleepers and the rail fastening devices on the sleepers on the over-road bridge and the concrete blocks in left of the over-road bridge end edge. Therefore, it is highly probable that plural wheels had been derailed and ran on the over-road bridge. (3) Traces in the forward section, toward Niitsu station, from the over-road bridge end edge The left side of the ballast were collapsed to forward continuously, and the slope was collapsed toward the compost house, in the forward section from the over-road bridge end edge. It is probable that these collapse of the embankment were caused by the concerned train that had been running on the over-road bridge as being derailed, ran on the ballast after that, and the 1st to the 3rd vehicles had fallen off from the embankment. It is probable that the traces in outside gauge of left rail found in the section from the over-road bridge end edge to around the sleeper No.71, were caused as the wheels had derailed to left and had been running on the track. It is probable that the traces on the rail fastening devices in the inside gauge of left rail, found in a part of the section to around the sleepers No.63 to No.108, were caused by being collided with the wheels. On the other hand, it is probable that the poles were folded and broken due to being collided by the 1st to the 3rd vehicles fallen off from the embankment, because these poles had been planted in left side of the track, as described in 2.3.2. It is highly probable that the damages of the overhead contact line suspension device etc., attached to the poles were caused by the accident, because the damages were existed in the place of the derailed trace on the track and in the forward and backward section including the stopped position of the concerned train.

3.2. Analysis on the Vehicles 3.2.1. Analysis on the Factors of the Derailment It is probable that there was no abnormal situation as caused the derailment in the vehicles of the concerned train, because the concerned driver and the driver, who operated the concerned train from Akita station to Sakata station, stated the that there was no abnormal situation in the vehicles of the concerned train as described in 2.1.2 (1) and 2.1.5 (1), and there was no abnormal data in the inspection records of the vehicles of the concerned train as described in 2.6.4.

3.2.2. Analysis on the Damages in the Vehicles It is probable that the damages, found in the vehicle bodies, the bogies, and the wheels in all vehicles of the concerned train, were caused by the occurrence of the accident, because it is probable that there was no abnormal situation in the vehicles of the concerned train as described in 3.2.1. In addition, it is probable that the hit traces in the tread corner of the left wheels in the 2nd to the 4th vehicles, described in 2.3.3.2 (6), 2.3.3.3 (7) and 2.3.3.4 (3), were caused as each

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wheel had collided with the sleepers and the rail fastening devices in the inside gauge of left rail in the forward track from the sleeper No.12b, as described in 3.1.2 (1) to (3).

3.3. Analysis on the Handling Train Operation As described in 2.7.2.2, it was prescribed that as the section between Sagoshi station and Kita-Amarume station was the normal control section, the speed control should be implemented when the wind speed was identified as exceeded 25 m/s, and the suspension of the train operation should be implemented when the wind speed was identified as exceeded 30 m/s. On the other hand, as described in 2.7.4, the chief dispatcher stated that the operation control was not carried out at the occurrence of the accident. It is highly probable that it was not in the status to implement the operation control under strong wind at the time of the occurrence of the accident, because the maximum wind speed in the records of the existing anemometer of the Company at 1 hour before the occurrence of the accident was 12 m/s at 19:02, as described in 2.8.3. The limited speed for the concerned train from the concerned bridge to the accident site was the maximum velocity 120 km/h, as described in 2.7.1.2 and 2.7.1.3. The concerned driver stated that he operated the notch off at about 110 km/h when the concerned train approached to the concerned bridge, and it is probable that the velocity of the concerned train passing Hiraoka level crossing was about 106 km/h calculated from the information memory in the level crossing protection device in the start point for warning of Hiraoka level crossing located at the backward of the concerned bridge, and the passing velocities calculated for the other level crossings were within the limited speed, as described in 2.1.2 (1) and 2.5.3. Therefore, it is probable that the concerned train had been running at the velocity within the limited speed in around the accident site. The handling operation by the drivers in the Company, in the status of strong wind were as prescribed in 2.7.3.2 and 2.7.3.3. The concerned driver stated as "The visibility in front of the track was well, wind was not so strong. When the train was passing the concerned bridge, wind was not so strong", and the maximum wind speed in the records of the existing anemometer at 1 hour before the occurrence of the accident was 12 m/s at 19:02, as described in 2.1.2 (1) and 2.8.3. Therefore, it is probable that the concerned driver was not in the situation to implement the operation control under strong wind, before the occurrence of the accident. Based on the above discussions, it is probable that there was no problem in the handling operation of the concerned train because the Company had not been in the situation to instruct the operation control at the occurrence of the accident, and the concerned driver had not operate the concerned train against the regulation of the Company such as the Implementing Standard for Train Operation, etc.

3.4. Analysis on the Weather Condition etc. 3.4.1. Analysis on the Results of Weather Observation As for the weather condition on the accident day, the low pressure moved to east as been growing, and the accident site was in the warm sector of the low pressure as described in 2.8.1. In addition, the existence of the clouds cluster, that the top of the clouds reached to about 4 to 6

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km that was tall as unusual in winter, were observed in the area of the warm sector, in the satellite image of the geostationary meteorological satellite. It is highly probable that these clouds cluster were composed of the cumulonimbus clouds because the height of the top of cloud was high, the shapes of the clouds were massive, and confirmed by the visual observation on the ground as described in 2.8.2. The linear echoes were observed in these cumulonimbus clouds cluster from NE to SW direction in the sky above the accident site, and there was the echo higher than in the peripheral as its top reached to about 6 to 8 km in the sky, as described in 2.8.4. It is probable that the movement of the echoes were in the following situations based on the analysis. (1) The whole linear echoes had been moving toward SE direction slowly. On the other hand, the individual strong echoes composed of the linear echoes had been moving at about 90 km/h toward ENE direction by the supposition based on the moving status of the echoes. (2) One of the strong echoes had moved in the sky along the area where a series of damaged by the strong wind had occurred described in 2.8.6, and passed around the accident site at about 19:15. Furthermore, the wind direction had changed from SW to WNW direction from 19:00 to 20:00, December 25, based on the observation in Sakata Observatory, and the westerly wind area and the southerly wind area had contacted each other in around Shonai area in the observation by the AMeDAS located in Yamagata Prefecture and its neighborhood, as described in 2.8.2. In addition, the wind direction changed in the height lower than 1 km in the observation of the wind profiler as described in 2.8.5. Based on the above discussion, it is highly probable that the shear line, i.e., the boundary line where wind direction and wind speed changes sudenly, had been existed in Shonai area at the time of the accident, and the wind direction had changed as the shear line had pass though over Sakata Observatory. In addition, it is probable that the shear line was corresponded to the movement of the linear echoes because the boundary of the wind directions had been moving toward SE direction slowly in Shonai area. In addition, it was snow and sleet etc., with thunder in Shonai area, based on the observed results by Sakata Observatory etc., and the statements of the passengers of the concerned train and the inhabitants etc., described in 2.8.2 and 2.8.7 (1). Based on the above discussions, it is probable that the weather in around the accident site at the time of the accident was in the status to easily induce the remarkable weather phenomena such as the gust of wind as the active cumulonimbus cloud cluster had been passing.

3.4.2. Analysis on the Damages by Strong Wind in around the Accident Site The damages by the strong wind in around the accident site were distributed in the belt shaped area of several ten meters to several hundred meters wide, from seaside, Hamanaka area of Sakata City, to about 14 km in ENE direction, Ishinazaka area of Sakata City. It is probable that these damages were caused by the passing echoes as one of the strong echoes had passed over the belt shaped area as described in 3.4.1, and it is hard to consider that different weather

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phenomena had caused damages separately in the belt shaped area. There were the continuous damages due to strong wind as some trees in the windbreak forest had folded in the area from Hamanaka area near the seaside to Kuromori area, and the snow-break fences, that had been designed as to withstand the instantaneous wind speed up to 40 m/s, had been scattered in Hirono area, as described in 2.8.6. On the other hand, as for the wind speeds observed in around the damaged area due to strong wind, the maximum instantaneous wind speed 36.9 m/s was observed at 19:07 on December 25, in the observation point at Shinkawa seaside near the damaged area, but the average wind speed was 10 to 20 m/s, and the maximum instantaneous wind speed was in the level of 20 to 25 m/s in the anemometers in the other many observation points, as described in 2.8.3. Based on the above discussions, it is probable that the damages due to strong wind had occurred in the area, narrow as the neighboring anemometers did not observe strong wind, corresponding to the passing same echo, and it is probable that the wind speed was faster than the observed values in the peripheral anemometers considering the levels of the damages. In addition, as described in 2.8.7 (1), it is somewhat likely that the damages due to strong wind was caused by the gust of wind because the inhabitants in the damaged area stated that the strong wind blew suddenly accompanied with the sound as rumbled. As the tornado, the down burst, the gust front, the dust whirl etc., described in 2.8.8, has the possibility to cause the damages due to strong wind such as in the accident, it is somewhat likely that the tornado or the down burst the damages were caused by considering the damaged status and its spread status, etc. in the concerned accident. There were many features of damages by the tornado, such as the belt shaped damaged area and there was the convergency of the distribution of the wind direction such as the neighboring trees fell to northerly and to easterly in the windbreak forest, from Hamanaka area near seaside to Kuromori area, as described in 2.8.6 (1). Based on these facts, it is somewhat likely that the tornado in the level of the Fujita scale F1 had been occurred from Hamanaka area to Kuromori area. However, it could not be determined that the weather phenomenon in around the accident site occurred at the time of the accident was the tornado or the down burst, because the whole damages were restricted in almost belt shaped area but the damaged areas were not continuous in the other areas, and there was no information to identify the phenomena on the wind direction of the wind caused the damages.

3.4.3. Analysis on the Weather Condition in the Accident Site The weather condition in the accident site at the occurrence of the accident were as follows. (1) As described in 2.8.6, the damages due to strong wind existed in dotted in the belt shaped area from near seaside to about 14 km distant to ENE direction, including the neighborhood of the accident site. Therefore, it is highly probable that the accident site was existed in the area of the belt shaped area. (2) It is highly probable that the existing anemometers were normally operated based on the

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results of the investigating analysis on the wind speed etc., implemented after the accident, as described in 2.12.1.3. In addition, it is probable that the place in around the accident site was not the place where the characteristics of the natural wind differs from the neighborhood, as described in 2.12.1.4. Furthermore, the almost similar trends were found in the wind speed in around the accident site and in around the existing anemometer as described in 2.12.1.6. It is probable that the possibility, that the wind speed in around the accident site at the occurrence of the accident had considerably exceeded the level of 20 m/s observed in the existing anemometer described in 2.8.3, was low as far as the local weather phenomena had occurred. (3) As described in 2.8.6 (5), the shed for agricultural machinery in around the accident site was collapsed. It was estimated that the instantaneous wind speed when the shed had collapsed was over 34 m/s, according to the analysis by professor Tamura et al. In addition, it is somewhat likely that the wind strong as 0.1 to 0.2 times stronger than the above wind speed blew on the embankment where the concerned train was running, considering the effects by the embankment as described in 2.12.1.5 and 2.12.2.2. It is somewhat likely that the wind speed on the embankment, at the time when the shed for agricultural machinery collapsed, was significantly exceeded the level of 20 m/s observed by the existing anemometer described in the above, based on the above discussions. (4) It is probable that the weather condition in around the accident site at the occurrence of the accident was in the status to easily induce the remarkable weather phenomena such as the gust of wind, as described in 3.4.1. In addition, it is probable that the damages due to strong wind was caused responding to the passing same echo as described in 3.4.2, and the echo caused these damages had passed around the accident site at about the time of the occurrence of the accident, as described in 3.4.1 (2). In addition, it is somewhat likely that the gust of wind blew at the accident site corresponded to passing of the echo, based on the statements of the concerned driver and the passengers that the strong wind blew suddenly just after the train had passed the concerned bridge, as described in 2.8.7 (2). Based on these results of the analysis, it is somewhat likely that the local gust of wind, that could not be observed by the anemometers installed in the neighborhood, had blown when the damages due to strong wind occurred corresponding the passing strong echo in the linear echoes in the accident site at the occurrence of the accident, as described in 3.4.3. However, it could not be determined that the gust of wind in the accident site was caused by the tornado or the down burst, because there was only insufficient information to be identified. In addition, it is somewhat likely that the wind speed of the local gust of wind was in the level of the 40 m/s instantaneous wind speed in the accident site, based on the descriptions in 2.8.3, 2.8.6 (2) and (5), and the following analysis described in the previous (3). (i) The instantaneous wind speed of 36.9 m/s was observed in the observation point in Shinkawa seaside near the seaside corresponding to the echo that caused a series of damages due to strong wind.

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(ii) The snow-break boards, in the snow-break fence that was designed to withstand the instantaneous wind speed of 40 m/s, had scattered in Hirono area. (iii) The estimated results, that the shed for agricultural machinery in around the accident site collapsed by the wind of the instantaneous wind speed over 34 m/s, was obtained. (iv) It is somewhat likely that the wind speed on the embankment where the concerned train was running becomes 0.1 to 0.2 times faster than the wind blew at the place of the shed for agricultural machinery by the effects of the embankment.

3.5. Analysis on Factors of the Derailment and the Vehicle Behaviors before and after the Derailment 3.5.1. Analysis on the Running Velocity in around the Accident Site It is probable that the concerned train had passed the section from the warning start point of Barano level crossing to the warning stop point of Nakadai level crossing, at the average velocity about 96 to 103 km/h, after that, had been accelerated and passed the warning start point of Hiraoka level crossing at about 106 km/h, based on the description in 2.5.3. In addition, the concerned driver stated that he operated the notch off at about 110 km/h when the concerned train approached to the concerned bridge, as described in 2.1.2 (1). Based on the above discussions, it is somewhat likely that the running velocity in around the accident site was about 100 km/h, based on the estimation for the case that the notch was turned off when the concerned train approached to around the warning start point of Hiraoka level crossing existed in backward of the concerned bridge.

3.5.2. Analysis on the Operation Control in around the Accident Site The earlier control section of the Company was designated by evaluating comprehensively the conditions such as the section considered as the critical wind speed of overturning was lower than that in the plane area such as the single-track deck bridge, as described in 2.7.2.4. The section between Sagoshi station and Kita-Amarume station of Uetsu Line was designated as the normal control section, and it is prescribed that the operation suspension should be implemented when wind speed reached to 30 m/s, as described in 2.7.2.2 and 2.7.2.5. The wind speed that the operation control should be implemented in the operation control sections in the existing lines in the whole country were prescribed as 25 m/s in 57 % of the total operation control sections, and 30 m/s in 37 % of the total operation control sections. Therefore, it is probable that the wind speed to implement the operation control in around the accident site was the general control value, as compared to the operation control sections in the whole country.

3.5.3. Analysis on the Critical Wind Speed of Overturning As described in 2.12.2.4 (2), as for the critical wind speed of overturning estimated by using the aerodynamic force factors etc., obtained from the wind tunnel test, in case that the running velocity of the train in around the accident site was set as 100 to 120 km/h supposed from the description in 3.3 and 3.5.1, the effect to the train was in its maximum when the wind direction

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angle of the natural wind against the train α was set in the level of 70°to 75°, here, the direction of the train running was set as 0°, and the right lateral direction was set as 90°, and the critical wind speed of overturning was over 30 m/s for the 1st vehicle, and over 40 m/s for the 2nd vehicle, considering the acceleration of lateral vibration of the vehicle body. In addition, when the natural wind direction α was changed by about 20° from the wind speed for the minimum critical wind velocity of overturning, i.e., 70° to 75°, the critical wind speed of overturning became higher by about 2 to 3 m/s. On the other hand, the critical wind speed of overturning, when the acceleration of lateral vibration of the vehicle body was set as 0, were around 40 m/s for the 1st vehicle and a little under 50 m/s for the 2nd vehicle. In addition, the results of the trial calculation of the critical wind speed of overturning using the simple equation were about 43 m/s for the 1st vehicle and about 45 m/s for the 2nd vehicle. It is probable that the critical wind speed of overturning of the 1st vehicle, that the critical wind speed of overturning was lower than that of the 2nd vehicle, was over 30 m/s but did not exceed 40 m/s considerably, based on the above results. Here, as the calculation of the height of the gravity center of the vehicle was not implemented after the remodeling works of the vehicles in the concerned train, as described in 2.6.3, the critical wind speed of overturning was estimated using the simple equation as described in 2.12.3 in order to estimate the affected level of the height of the gravity center of the vehicle body to the critical wind speed of overturning. The trial calculation, when supposed as the height of the gravity center of the vehicle body became 10 cm higher, showed the results that the critical wind speed of overturning for the 1st and the 2nd vehicles decreased by about 0.5 m/s. It is probable that the change in these levels would not affect to the critical wind speed of overturning.

3.5.4. Analysis on the Occurrence of the Derailment of the Vehicles It is probable that there was no abnormal situation considered as caused the derailment in the track and the vehicles, as described in 3.1.1 and 3.2.1. Then, it is probable that the tracks and the vehicles had the low possibility to cause the derailment of the vehicles. In addition, the concerned driver stated as "there was no sense that the concerned train hit something or trampled something fallen" when the concerned train tilted and overturned, as described in 2.1.2 (1). There was no trace considered as caused by the wheels in backward track from the sleeper No.12b as described in 2.3.1. It is probable that the trace on the rail surface in the backward section from the over-road bridge start edge were considered as caused by wheels and there was no trace considered as caused by something else as described in 3.1.2 (1). Then, it is probable that there is no possibility for the concerned train to derail as being hit by something blown due to strong wind. It is probable that the possibility, that the wind speed in around the accident site at the occurrence of the accident had considerably exceeded the level of 20 m/s observed in the existing anemometer, was low as far as the local weather phenomena had occurred., as described in 3.4.3 (2). On the other hand, it is probable that the critical wind speed of overturning of the 1st

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vehicle of the concerned train was over 30 m/s but did not exceed 40 m/s considerably, as described in 3.5.3, and it is somewhat likely that the wind of the instantaneous wind speed in the level of 40 m/s blew in the accident site, as described in 3.4.3. Then, it is somewhat likely that the local gust of wind exceeding the critical wind speed of overturning, that could not be observed by the anemometers installed in the neighborhood, had blown suddenly. As for the status of the occurrence of the derailment, it is probable that the 1st vehicle or the 2nd vehicle derailed first, because it is somewhat likely that the 3rd vehicle ran onto the 1st vehicle after the 1st vehicle had overturned and halted. Here, behaviors of each vehicle before and after the derailment is described in the following paragraph 3.5.5. Furthermore, the critical wind speed of overturning for the 1st vehicle was lower than that for the 2nd vehicle, and it is somewhat likely that the 2nd vehicle derailed to inside gauge of left rail, because the left side of the rear end surface of the 1st vehicle approached to the front surface of the 2nd vehicle as the front part of the 1st vehicle, already derailed to outside gauge of left rail, moved to left, and the 2nd vehicle had been acted by the force to push to right as in the status to collide with the previously derailed 1st vehicle from behind. Therefore, it is somewhat likely that the 1st vehicle had derailed left at first. Based on the above results of the analysis, it is somewhat likely that the 1st vehicle of the concerned train, as suffered from local gust of wind from right exceeded the critical wind speed of overturning, tilted to left and derailed to left as the right wheels were raised up, because the concerned driver and the passengers stated as "the storm of snow blown up from the ground and the sleet etc., had blown from right suddenly, and the vehicle tilted to left just after something hit the window glasses", as described in 2.1.2 (1), 2.1.3.1 (1) and 2.1.3.2 (1). [Refer to Attached Figure 50]

3.5.5. Analysis on the Behavior of the Vehicles before and after Derailed As it could not be determined the precise behavior of each vehicle from the status and the traces in the accident site and the information of the statements etc., because it is highly probable that the behaviors of each vehicle before and after the derailment was in complex situation. However, it is somewhat likely that the behaviors of each vehicle before and after the accident was as follows, based on the process of the train operation described in 2.1, the information on the physical damages described in 2.3, the analysis on the railway facilities described in 3.1, and the analysis on the occurrence of the derailment of the vehicles described in 3.5.4.

3.5.5.1. The 1st vehicle (1) It is somewhat likely that the front part of the sleeper No.1 was folded and damaged and the sleeper No.2 was folded and severely damaged and moved to forward as being acted by the considerable shocks by the wheels, as described in 3.1.2 (2). It is somewhat likely that front part of the 1st vehicle derailed and moved to left as the 1st vehicle was hit by the gust of wind from right, as described in 3.5.4. Therefore, the 1st vehicle had tilted to left by the gust of wind from right and the front bogie derailed to left at around the sleeper No.2, as

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described in 3.5.4, while the concerned train was running in the backward of the over-road bridge, in the direction to Akita station, after passed the concerned bridge. (2) After the front bogie had derailed, it is probable that the left wheel moved to left still more in the forward section from the sleeper No.14 as described in 3.1.2 (2). Therefore the 1st vehicle moved to the front left and the rear bogie derailed to left at around the sleeper No.7b where there was the last trace in the direction to Akita station in outside gauge of left rail. (3) The sleepers on the over-road bridge were severely damaged as described in 2.3.1 (2), the left shoulder of the ballast and the left slope of the embankment were collapsed continuously as described in 2.3.1 (3), and the poles No.VI and No.VII were folded and broken as described in 2.3.2. Therefore, the 1st vehicle caused these damages and decelerated as turned the front part to left. (4) The vehicle body tilted to left still more, fell from the embankment, overturned, and skidded. After that, the front part faced to right of the north-west corner of the compost house, the rear part faced to left, and the center of the roof of the vehicle body collided to the north-west corner of the compost house and transformed to as concave, based on the collapsed status of the left shoulder part of the ballast and the left slope of the embankment described in 2.3.1 (3), and the stopped status and the damaged status of the 1st vehicle described in 2.3.3.1.

3.5.5.2. The 2nd vehicle (1) As described in 3.1.2 (1), there were traces considered as caused by some left wheels in all 4 axles in the front and the rear bogies of the 2nd vehicle, all 2 axles in the rear bogie of the 3rd vehicle, or the 1st axle in the front bogie of the 4th vehicle, on the rail fastening devices and the sleepers in inside gauge of left rail, respectively, in backward from the over-road bridge, in the forward track from the sleeper No.12b, as described in 2.1.2 (1). It is probable that the front bogie of the 1st vehicle had moved to left still more in the forward section from the sleeper No.14, as described in 3.5.5.1 (2). It is somewhat likely that the 2nd vehicle derailed as being acted by the force to right from the rear part of the 1st vehicle that had moved as the front part faced to left, as described in 3.5.4. The position of the trace on the concrete block in the over-road bridge end edge and the sleeper No.12 was in the distance about the length of a vehicle. Therefore, it is probable that the flaws from around center to the gauge corner on the rail surface of left rail from the sleepers No.16b to No.15b and the traces on inside gauge of left rail in the forward section from around the sleeper No.12b, were caused as some left wheel in the 2nd vehicle had been running. (2) The vehicle body of the 2nd vehicle had been tilted to left as the right wheel had been raised already when the 1st vehicle derailed, because there was no trace as caused by running wheels on right rail and the rail fastening devices etc., on right rail and in inside and outside gauge of right rail in the backward of the over-road bridge and in around the over-road

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bridge, as described in 2.3.1. (3) The 2nd vehicle tilted to left and the front bogie, followed by the rear bogie, derailed to inside gauge of left rail as described in the above (2), caused as being acted by the force toward right from the 1st vehicle decelerated due to be derailed, while the concerned train was running in the rear part of the over-road bridge, because there were trace considered as caused by the plural running wheels on the rail fastening devices etc., in the inside gauge of left rail in the backward of the over-road bridge. (4) The left wheels in the front and the rear bogies of the 2nd vehicle climbed over the left rail at around the sleeper No.19, as the 2nd vehicle was guided to the front left as being tilted to left and being coupled with the derailed 1st vehicle, based on that there was no damage of the rail fastening device in inside gauge of left rail in the forward section from the sleeper No.19 and there were the traces considered as the different wheels were running in inside and outside gauge of left rail on the sleeper No.19 as described in 3.1.2 (2). (5) The 2nd vehicle fell from the embankment as being tilted to left, overturned, skidded, and collided as the rear part of the 1st vehicle pushed the northern surface of the compost house, and stopped, based on the collapsed status of the left side of the ballast and the left slope of the embankment described in 2.3.1 (3), and the stopped status and damaged status of the vehicle described in 2.3.3.2.

3.5.5.3. The 3rd vehicle (1) There was no flaw on the rail surface of right rail until to around the sleeper No.70 as described in 2.3.1 (3). There was no noticeable damage on the sleepers inside gauge near right rail until to around the sleeper No.71. The rail fastening devices and the sleepers in inside gauge of left rail in forward section of the over-road bridge were damaged intermittently. The hit traces were found in the tread corner of the left wheels of all axles in the rear bogie of the 3rd vehicle. Based on the above information, the 3rd vehicle collided with the rear of the decelerated 2nd vehicle, after the 1st and the 2nd vehicles had derailed, and the vehicle body tilted to left and the left wheels derailed to inside gauge of left rail, and the left wheels climbed over left wheel as guided by the 2nd vehicle and derailed to left. (2) The rear part of the 2nd vehicle had been halted in the status as being hanged by the embankment, as described in 2.3.3.2, and the collided traces were found in the rear surface of the vehicle body of the 2nd vehicle. The hit traces were found in the front surface of the vehicle body of the 3rd vehicle as described in 2.3.3.3 (1). The passenger boarded on the 3rd vehicle stated that the vehicle body gradually tilted to right and skidded on the ground in the status as being tilted completely, as described in 2.1.3.1 (6). The vehicle body of the 3rd vehicle had been overturned as its right side down. Based on the above information, the 3rd vehicle moved toward the west surface of the compost house as the vehicle boy had been tilted to right, in the status as being pushed from backward by the 4th vehicle, after collided with the rear part of the 2nd vehicle, which was

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decelerated due to be derailed, and raised up, then, derailed and fell from the embankment. (3) The fretting traces were found in the front part of the right side surface of the 1st vehicle as described in 2.3.3.1 (3). The front bogie of the 3rd vehicle had been fallen in around the front part of the 1st vehicle, as described in 2.3.3 (7), and the vehicle body of the 3rd vehicle had been halted in the reverse direction to the running direction of the train. The compost house had been collapsed by the collision with the concerned train as described in 2.3.4.2. Based on the above information, the front bogie of the 3rd vehicle fell off from the vehicle body as the 3rd vehicle ran over around the right side surface of the driving cab of the 1st vehicle that had been halted due to being collided with the compost house, and the front part of the 3rd vehicle collided to around center of the roof of the compost house. After that, the vehicle body of the 3rd vehicle rotated in the horizontal plane in CCW as the front part of the vehicle body as its center in the status as the front part of the vehicle body had been supported by the steel frames of the roof of the compost house, then, fell to the west of the compost house and halted as being coupled with the 4th vehicle.

3.5.5.4. The 4th vehicle The 4th vehicle had been halted in the status that the front part of the 4th vehicle had been contacted with the rear part of the 3rd vehicle, and the front and the rear bogies of the 4th vehicle had been staying on the track as described in 2.3.3.4. Considering the above information and the derailed status of each wheel, after the 4th vehicle moved being as coupled with the 3rd vehicle and derailed as being guided to the front left by the 3rd vehicle, the front and the rear bogies fell away from the vehicle body in cooperated with the CCW rotation of the 3rd vehicle in around the front part of the 3rd vehicle collided with the western roof of the compost house, then, the front part of the vehicle body once moved to right of the track due to be pulled by the 3rd vehicle and be pushed by the 5t vehicle at the same time. After that, the 4th vehicle rotated in the horizontal plane CCW, and stopped as the front part of the vehicle went over to the left side of the track and the rear part of the vehicle body went over to the right side of the track. As the results, the vehicle body of the 4th vehicle had been halted as to cross the up and down tracks from left to right.

3.5.5.5. The 5th vehicle The 5th vehicle ran as being coupled with the 4th vehicle, collided to the 4th vehicle which was decelerated due to be derailed, and ran as being pushed by the 6th vehicle, then, the front bogie derailed to right and fell away from the vehicle body, because the front part of the 5th vehicle had been halted in the status as being contacted with the rear part of the 4th vehicle as described in 2.3.3.5. After that, the rear bogie derailed to right as the the front part of the vehicle body of the 5th vehicle moved to right of the running direction as being pushed the 4th vehicle. As the result, the 5th vehicle had been halted as the front and the rear parts stopped on the down track and the up track, respectively.

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3.5.5.6. The 6th vehicle The 6th vehicle ran as being coupled with the 5th vehicle, collided to the rear part of the 5th vehicle which was decelerated due to be derailed, then, only right wheel of the 1st axle in the front bogie derailed to inside gauge and stopped, based on that the 6th vehicle had been halted at the backward of the 5th vehicle, as described in 2.3.3.6.

3.6. Analysis on the Survival Factors 3.6.1. Analysis on the Causes of Death and Injuries 3.6.1.1. Status of the dead persons. As described in 2.2.2 and 2.2.4, the all 5 dead persons were boarded on the 1st vehicle, and dead by being crushed to death, the brain contusion, or the entire body contusion due to the shock by external injuries. Among 5 dead persons, 4 persons were found in around the center of the cabin, and one person was found from beneath the vehicle at around the center of the vehicle. On the other hand, the vehicle body of the 1st vehicle had been folded in concave as near the center of the roof had been collided to the compost house as the vehicle had been overturned, and the roof of the vehicle body had been crushed toward the cabin from the center to the rear part of the vehicle body, as described in 2.3.3.1. Based on the above information, it is probable that the death of persons were caused by sandwiched by the cabin instruments due to the remarkable reduction of the space in the cabin, or by crushed to death under the vehicle after thrown out to outside vehicle by the impact of the overturning or the collision.

3.6.1.2. Status of the injured persons As described in 2.2.2, the 37 passengers etc., among the total 44 passengers etc., were dead or injured. Among 35 persons in the 1st to the 3rd vehicles, 5 persons were dead, and 29 persons were injured. On the other hand, it is probable that many injured persons had been thrown out from their seats by the shocks due to collision of the vehicle to the compost house and the overturning, and bumped into the wall in the cabin or the seats etc., because all of the 1st to the 3rd vehicles had been fell to left from the embankment, overturned, and severely damaged, as described in 2.3.3.1 to 2.3.3.3. In addition, as described in 2.2.5 (3), it is probable that the levels of the injuries of the many persons, who broke their bones and considered as injured in relatively sever level, were affected by that their bodies were thrown out from the seats, because many persons had been staying in the place different from they were before the accident compared to the persons who stayed in the same position as before the occurrence of the accident.

3.6.2. Analysis on the Actions of the Emergency Rescue Organization etc. As described in 2.9.4.3, the rescue teams arrived at the accident site at about 19:32, about 18

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minutes after the occurrence of the accident, and implemented the triage and the rescue activities for the injured persons in the cabin from about 19:42, in the severe blizzard. In addition, transportation of the injured persons to the hospitals started from about 20:00, and the medical treatment teams arrived at about 20:50 and implemented the medical treatment activities in the accident site. All injured persons, except for an injured person who was difficult to be rescued as being sandwiched by the cabin facilities, were transported to the hospitals by about 21:00. An injured person, who was difficult to be rescued as being sandwiched by the cabin facilities, was rescued using the hydraulic rescue tools as being dosed the medicine to prevent the crash syndrome, and transported to the hospital at about 23:55, then, the transportation of all injured persons to the hospitals were completed. It is probable that the actions by the emergency rescue organization and the medical institutions were implemented almost properly, although the rescue activities were implemented in the bad condition as in the blizzard.

3.7. Analysis on the Train Protection 3.7.1. Analysis on the Handling of Train Protection by the Crews of the Concerned Train It is highly probable that the concerned conductor sent the alarm signal from the train protection radio device in the 6th vehicle at about 19:15, as described in 2.10.5. As the results, it is highly probable that the opposite 831D train and the following train received the alarm signal issued from the train protection radio device of the concerned train in Amarume station and Higashi-Sakata station, respectively, and all trains running toward the accident site were stopped, as described in 2.10.8 and 2.10.9. In addition, it is probable that the train dispatcher, who received the first report from the conductor, arranged the procedure of the operation suspension of the related trains immediately, as described in 2.1.4 (1). However, it is probable that the measures of the train protection against the opposite train by the ignition of the fuse for vehicle, the portable fuse, and the rail clamp shunt, hereinafter referred to as "the train protection tools etc.", prescribed in the Implementing Standards for Train Operation, etc., of the Company, were not implemented, as described in 2.10.2 and 2.10.6. As for these situations, it is probable that the concerned driver was in the status as difficult to find the train protection tools etc., in the driving cab of the 1st vehicle, because the whole vehicle body of the 1st vehicle fell off to left from the embankment, overturned, and damaged severely, and the concerned driver stated that he could not find the train protection radio device, the train radio device, etc., as it was dark in the driving cab, as described in 2.1.2 (1) and 2.3.3.1. On the other hand, it is probable that the train protection tools etc., in the 6th vehicle was in the status to be used to implement the measures of the train protection against the opposite train, because the 6th vehicle had been halted in the same status as in running on the up track, as described in 2.1.2 (2) and 2.3.3.6. In addition, it is probable that the crews of the concerned train did not comprehend the status of operation suspension of the related trains by about 19:30, because the train dispatcher stated

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that he communicated to the concerned driver that the operation suppression for the related trains was already arranged at about 19:30, as described in 2.1.4 (1). It is probable that the measures of operation suspension against the opposite train using the train protection tools etc., should be implemented promptly after operated the train protection radio device, at the occurrence of the accident, because the train protection should be implemented at top priority and surely in order to prevent the secondary damages.

3.7.2. Analysis on the Handling of the Train Protection etc., Prescribed in the Company It is highly probable that all trains operated toward the accident site had stopped due to receive the alarm signal sent by the train protection radio device of the concerned train, as described in 3.7.1. However, when the train protection radio device was in trouble, the stop signal was not displayed, therefore, the measures of the train protection for the opposite trains should be implemented promptly in order to prevent the secondary damages, as described in 2.5.4. Then, it is probable that the Company had been prescribed it in the regulations and implemented the education, as described in 2.10.2 and 2.10.4. Among these regulations, the Handling Manual for Operation in Abnormal Situation, driver edition and conductor edition, described in 2.10.2, prescribed that to indicate the stop signal by the alarm signal of the train protection radio device, and implement the measurement of train protection by the train protection tools etc., then communicate with the train dispatcher. On the contrary, the Implementing Standard for Conductor described in 2.10.3, prescribed on the contents of the work in the handling of the train protection radio device, as to push the switch if the train protection is required, and the description as to communicate with the driver and the dispatcher when sent the alarm signal, was followed. As the Implementing Standard for Conductor describes the handling of the train protection radio device, but there was a fear to induce misunderstanding on the procedure of the method of the train protection, therefore, it is probable that there was the necessity to make these descriptions consistent each other. Furthermore, when the driver could not implement the train protection procedure as in the concerned accident, the implementation by the other crews was required, but in this case, it is probable that the minute investigation and the enrichment of the regulations, and the implementation of the education to make the train crews well understand the meanings of each procedure of the train protection were required, as it is necessary to act as prompt and certainly without mistakes in the procedures. In addition, it is probable that the stop signal against the opposite trains was not indicated in the block signal device, etc., because the track circuit was in the status as not short-circuited by the axles if the all axles in the concerned train had been derailed in the concerned accident. In these case, the train protection against the following trains was also needed in addition to the train protection against the opposite trains, as different from the contents of the education described in 2.10.4. Therefore, it is desirable to study the methods of implementation and the

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methods of description in the regulations on the handling of the train protection when all axles had been derailed, in addition to the education described in 2.10.4. In addition, it is probable that the concerned driver did not implement the arrangement of the preventing wheel rolling because he judged as there was no need to implement it considering the derailed status, as described in 2.10.13, as it is probable that there is the case that required the measurement of the preventing wheel rolling according to the situation, in the section where there was the gradient as in the accident site.

3.8. Analysis on the Concept of the Measures against Strong Wind 3.8.1. The Effective Use of the Weather Information It is probable that the measures based on the instantaneous prediction of the gust of wind due to the tornado or the down burst were difficult at present, because the mechanism of these weather phenomena were not elucidated well and the observation system or the system of information provision were not established at present. However, the enforcement of the observation system against the phenomena that lead the gust of wind such as the preparation of the Doppler radar monitoring cumulonimbus which had the possibility to induce the tornado etc., and have been studying on the effective use of the observed results and the information provisions etc., in the JMA. Therefore, it is probable that the railway operators were also required to study the measures such as the active acquisition of the high reliable weather information based on the new knowledges. In addition, it is probable that the operation control using the existing weather information including the information observed in the Company, was open for further improvement, in order to measure the phenomena including the local gust of wind. As an example, it is probable that the operation control for strong wind was determined based on the information etc., of the measuring devices such as the track side anemometers etc., installed by the Company, as referred to the weather information in the neighborhood, as usual, but it could not be judged on the changes of weather phenomena in around the track only by the observed results in the track side, because the change of weather phenomena did not depend on only the change along the track. Therefore, it is probable that the proper measures being comprehend the weather phenomena in the plane based on the information from outside of the Company, were required, in order to measure the various changes of the weather phenomena. Particularly recent years, the information on the weather warnings etc., were issued to the subdivided area, the live status could be obtained more promptly by the improved weather observation system, and the new information such as the tornado advisories had been provided. Therefore, it is probable that it is effective for the railway operator, to measure properly by using the weather information well, and to implement the research as being interested in the trends in the field of weather observation, and watching the progress in the weather observation technologies and the information processing technologies etc. Based on the above information, it is probable that it is required to establish the situation to obtain the latest weather information promptly, and to study the measures of effective use of

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these weather information, such as to set up early advisory formation based on these weather information in the train operation management, referring the opinions of the weather concerned persons, based on the recent changes in the situation.

3.8.2. Implementation of the Measures against Strong Wind It is probable that the critical wind speed of overturning was in the trend to decrease as the running speed of the train increased as described in 2.12.2.4 (2), and affected by the wind directions, in addition to the structures of the vehicles etc. It is probable that the wind speed becomes large on the embankment, as described in 2.12.1.5 and 2.12.2.2. Based on the above information, it is probable that various factors should be considered to secure the safe train operation under strong wind. Therefore, it is probable that the study on the comprehensive measures against strong wind was required including the measures such as to enrich observation of the wind speed, to install the windbreak fences, etc., base on the latest researches on the vehicle behaviors against wind, in order to promote the improvement of the safeness responding to the increased velocity of the running train and the change of the vehicle structures etc., in recent years. Here, it is probable that the regulations should be required to be revised promptly based on the actual situations in order to implement the proper operation control thoroughly, as there was the situation that the Implementing Standards for Train Operation estranged from the actual situation on the operation control under strong wind, as described in 2.7.3.4.

3.9. Summary of the Results of the Analysis 3.9.1. Analysis on the Railway Facilities It is probable that there was no abnormal situation considered as caused the derailment in the railway structures and the tracks etc. It is probable that the traces in the rail fastening devices etc., in inside gauge of left rail in the section between the over-road bridge start edge and the sleeper No.12b in the direction to Akita station, were caused as being hit by around the tread corner of the dropped left wheels. i.e. some of the left wheel in the 2nd to the 4th vehicles. In addition, it is probable that the damages etc., of the rail fastening devices etc., in outside gauge of left rail in the forward section from the sleeper No.7b, were caused as the derailed left wheels were running. The sleeper No.1 was damaged as lost and damaged only in the front part, and the sleeper No.2 was severely damaged, as different from the traces in the other sleepers in the over-road bridge. It is somewhat likely that these situations were caused as being hit significantly by the left wheels of the 1st vehicle which derailed at first and dropped in around there. It is probable that the plural wheels which had been derailed to inside gauge, ran over the left rail and moved to outside gauge, based on the situation of the traces in around the sleeper No.19.

3.9.2. Analysis on the Vehicles It is probable that there was no abnormal situation considered as caused the derailment in the

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vehicles of the concerned train. In addition, it is probable that the damages of the vehicle bodies, the bogies, the wheels found in all vehicles were caused be the occurrence of the accident.

3.9.3. Analysis on Handling Train Operation It is probable that the Company was not in the status to implement the operation control under strong wind at the time of the occurrence of the accident, because the maximum wind speed in the records of the existing anemometer before the occurrence of the accident was 12 m/s. It is probable that the concerned train had been running at the velocity within the limit speed as 120 km/h, in around the accident site. In addition, it is somewhat likely that the velocity of the concerned train running in around the accident site was in the level of about 100 km/h, based on the calculation in the assumption that the notch was turned off at about 110 km/h in around the warning start point of Hiraoka level crossing in backward of the concerned bridge. It is probable that the concerned driver was not in the situation that he could operate the handling of the operation under strong wind, before occurrence of the accident.

3.9.4. Analysis on the Weather etc. 3.9.4.1. Analysis on the results of weather observation It is probable that the weather was in the status as easy to induce the remarkable weather phenomena as the gust of wind etc., as the active cumulonimbus cloud cluster were passing in around the accident site at the time of the occurrence of the accident.

3.9.4.2. Analysis on the damages by strong wind in around the accident site The damages by strong wind were distributed in the belt shaped area of several ten meters to several hundred meters wide and about 14 km long, from seaside to ENE direction. It is probable that these damages by strong wind occurred responding the passage of the same echoes in the narrow area where the anemometers located in the neighborhood did not observed, and it is probable that the wind speed of the strong wind was larger than the values observed in the peripheral anemometers, based on the levels of the damages. It is somewhat likely that the phenomenon caused the above damages by the strong wind was the tornado or the down burst. It is somewhat likely that the tornado had occurred in the area from Hamanaka area in around seaside to Kuromori area, but it could not be determined that the damages in the other area were caused be the tornado or the down burst.

3.9.4.3. Analysis on the weather in around the accident site It is probable that the accident site was not the place where the characteristics of the natural wind did not show the property of weather different from that in the neighborhood. In addition, the wind speeds in around the accident site and in around the existing anemometer showed the similar trends. According to the analysis be Professor Tamura, et al., it was estimated that the instantaneous

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wind speed over 34 m/s had blown, as the compost house in around the accident site had been collapsed. Then, it is somewhat likely that the strong wind, as 0.1 to 0.2 times larger than the estimated wind speed, had blown on the embankment where the concerned train had been running, considering the effects by the embankment. In addition, the instantaneous wind speed 36.9 m/s was observed in Shinkawa Seaside and the windbreak boards of the windbreak fence, designed to withstand the instantaneous wind speed 40 m/s, in Hirono area had been scattered. Based on the above information, it is somewhat likely that the local gust of wind of about 40 m/s, that significantly exceeded the observed value in the existing anemometers, had blown in the accident site.

3.9.5. Analysis on Factors of the Derailment and Vehicle Behaviors before and after the Derailment 3.9.5.1. Analysis on the operation Control in around the Accident Site The section between Sagoshi station and Kita-Amarume station of Uetsu Line was designated as the normal operation control section, and prescribed as to implement the speed control at the wind speed 25 m/s, and to implement operation suspension at the wind speed 30 m/s. It is probable that these were the popular control values compared with the operation control sections in the whole country.

3.9.5.2. Analysis on the critical wind speed of overturning It is probable that the critical wind speed of the 1st vehicle, which was considered the possibility to derail as first, was higher than 30 m/s but not exceed 40 m/s significantly, in the velocity range from 100 to 120 km/h, from the results calculated using the aerodynamic force coefficient obtained from the wind tunnel test.

3.9.5.3. Analysis on the occurrence of the derailment of the vehicle As it is probable that there was no abnormal situation as caused the derailment in the track and the vehicles, it is probable that the possibility, that the track and the vehicle had related to the derailment of the derailment, was low. It is probable that there was no possibility as the concerned train derailed due to being contacted with the objects flown by the strong wind. It is somewhat likely that the 1st vehicle of the concerned train tilted to left, and the right wheels were raised up from rail and derailed to left, because the concerned train was hit by the local gust of wind, strong as exceeded the critical wind speed of overturning from right. As for the 1st to the 3rd vehicles that had been fallen from the embankment overturned and derailed, it is somewhat likely that the 3rd vehicle ran over the fallen and halted 1st vehicle. The critical wind speed of overturning was low in the 1st vehicle compared to the 2nd vehicle. It is somewhat likely that the left wheel of the 2nd vehicle derailed to inside gauge of left rail as in the status that the 2nd vehicle had collided with the 1st vehicle which had already been derailed. Therefore, it is probable that the 1st vehicle derailed at first and the 2nd vehicle and

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the 3rd vehicle derailed in turns.

3.9.6. Analysis on the Survival Factors 3.9.6.1. Analysis on the Factors of Death and Injuries It is probable that the dead persons were sandwiched by the cabin facilities in the extremely reduced space in the cabin as the roof had been crushed toward the cabin from center part to rear part of the vehicle body of the 1st vehicle, or thrown to outside vehicle by the impact of the overturning or the collision and crushed to death under the vehicle. It is probable that many injured passengers hit the walls, seats etc., in the cabin as being thrown from their seat due to the impacts by the collision of the vehicle and the compost house and the overturning.

3.9.6.2. Analysis on the actions of the emergency rescue organizations etc. It is probable that the actions of the emergency rescue organizations and the medical treatment organization had been implemented properly even though it was the rescue activities under bad condition as in blizzard.

3.9.7. Analysis on the Train Protection Procedures 3.9.7.1. Analysis on handling train protection procedures by the crews in the concerned train It is highly probable that all trains running toward the accident site had stopped as received the alarm signal that was sent from the train protection radio device in the 6th vehicle of the concerned train operated by the concerned conductor. It is probable that the crews of the concerned train did not implement the measures of the train protection against the opposite trains using the train protection tools etc., in the situation that they did not comprehend the status of the operation suspension for the related trains. It is probable that the measures of the train protection against the opposite trains should be implemented certainly, because it is necessary to implement the train protection at the top priority in order to prevent the secondary damages.

3.9.7.2. Analysis on handling train protection prescribed in the Company It is probable that the Company should investigate thoroughly and enrich the regulations and let the related staffs understand well by the education etc., in order to be able to act promptly and properly unless to mistake the procedures, even when the driver could not implement the train protection procedures immediately and the other crew should implement the train protection procedures as in the concerned accident.

3.9.8. Analysis on the Concept of the Measures against Strong Wind 3.9.8.1. The effective use of the weather information It is probable that the railway operators were also required to study the measures such as the active acquisition of the high reliable weather information based on the new knowledges, considering the recent changes in the situation such as the enforcement of the observation

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system against the phenomena that lead the gust of wind such as the preparation of the Doppler radar in the JMA, etc. In addition, it is probable that it is effective to implement the proper measures of the operation control by using the most of the live information and the predictions by the weather information, in addition to the measures based on the information from the measuring instruments etc., installed in the track side by the Company's route, in order to measure the situation including the local gust of wind. Therefore, considering the above changes in the situation, it is probable that the studies are required to the measures of effective use of weather information, referred to the opinions of the weather concerned persons, by established the situation to obtain the latest weather information promptly, and set up early advisory formation etc., by using these weather information in the train operation management.

3.9.8.2. Implementation of the measures against strong wind It is probable that the study on the comprehensive measures against strong wind was required including the measures such as to enrich the observation of wind speed, to install the windbreak fences, etc., based on the latest researches on the vehicle behaviors against wind, in order to promote the improvement of the safeness responding to the increased velocity of the train running and the change of the vehicle structures etc., in recent years.

4. PROBABLE CAUSES

It is probable that the vehicles in the concerned train, while running in the straight section of the embankment structure and passed by the concerned bridge, tilted to left as being hit by the local gust of wind as exceeded the critical wind speed of overturning from right, them, the 1st to the 3rd vehicles derailed, fell from the embankment and overturned, in addition, the 4th to the 6th vehicles also derailed in the accident.

5. REMARKS

5.1. Studies on the Measures against Strong Wind The "Meeting on Measures against Strong Wind in Railway" consisted of the Ministry of Land, Infrastructure, Transport and Tourism, MLIT, the JMA, the railway operators, et al., had been studied on the measures against strong wind, and the railway operators has been enforced the measures such as the installation of the new anemometers etc., after the occurrence of the accident. However, the railway operators should endeavor further enrichment of the understandings and the monitoring system of the status of strong wind in around the railway track, in order to implement more proper operation control in the required place, by using effectively the weather information such as the weather warnings issued by the JMA, in addition to the observed results in the anemometers installed by the Company. In addition, the railway operator should study on the

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proper measures against strong wind, comprehensively considering the factors affected to the train operation under the strong wind such as the increased velocity of running train, changes in the vehicle structures, installation of the windbreak fences etc.

5.2. Research on the Measures against Gust of wind The JMA started to provide the tornado advisory information from March, 2005, which should be studied its effective use, when taking the measures against the local gust of wind as in the concerned accident, but it is probable that there was still the technical limits in the degree of its accuracy. However, the railway operators should endeavor sincerely to the realization of the effective measures against dust of wind, by implementing the research activities in the broad area as keeping interests in the new trends of the meteorological field, and watching the progress in the weather observation technology and the information processing technology etc. In addition, it is expected that the JMA manages as to respond the social needs such as to improve accuracy and to detail in the smaller lattice information on the tornado advisory information etc., in the future, as the railway system is the public transportation that is required to operate properly and accurately.

6. ACTIONS TAKEN

6.1. Measures Taken by the Company (1) Installation of the windbreak fences The Company installed the windbreak fences in the 11 places in the 5 sections including the concerned bridge, in addition to the existing windbreak fences in the 4 places in the 4 sections. (2) Introduction of the strong wind alarm system The strong wind alarm systems, which predict the maximum wind speed until to several 10 minutes ahead based on the time series analysis method using the wind speed data observed continuously, were introduced in the 59 sections in the 16 lines, including the section between Kita-Amarume station and Sagoshi station, in addition to already installed section, i.e., the 6 sections in 1 line, by the end of February 2008. (3) Additional installation of anemometers in the existing operation control section The Company decided to install plural anemometers basically in the existing operation control section. The 312 anemometers were additionally installed in the existing lines of the Company, including the concerned bridge, by the end of February 2008. (4) Establishment of the Disaster Prevention Laboratory The Disaster Prevention Laboratory was established in the Research and Development Center of JR East Group, that is the organization for research and development in the Company, in order to accumulate the scientific knowledge on the meteorological phenomena and the whole natural phenomena, in the Company. (5) Confirmation of the operation control section by drawing up the strong wind map The strong wind map by the simulation based on the wind status in the sky and the

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topography was drawn up, and the reconfirmations of the operation control sections by the staffs in each site were implemented. Then, the Company decided to designate the 75 new operation control sections, in addition to the existing 221 operation control sections under strong wind, and already started the operation in some sections. (6) Trial implementation of the operation control by the effective use of weather information The operation control method, that the train operation was decided by combining the indices such as passage of the cold front, the height of the cumulonimbus cloud, the intensity of the echoes etc., using the weather information effectively, has been implemented as trial in the sections between Niitsu station and Sakata station of Uetsu Lin and between Niigata station and Shibata station of Hakushin Line, from January 2008. (7) The Company prescribed the "establishment of headquarter to measure the accidents in the Head Office" in the regulation on December 2007.

6.2. Measures Taken by the Ministry of Land, Infrastructure, Transport and Tourism The Railway Agency of the MLIT, issued the instruction on the implementation of the urgent inspection involved in the anemometers in view of the accident, on December 26, 2005. In addition, the Railway Agency established the Meeting on Measures against Strong Wind in Railway Systems and exchanged the information on the concerned accident and studied on the possibilities etc., of the measures against strong wind that can be implemented urgently. After that, the Railway Agency put together the intermediate report on the results of the urgent inspection on March 3, 2006, and at the same time, instructed the urgent measures against strong wind as follows. (1) Installation of the anemometers in the "Path of the Wind". (2) Adding the alarm functions when the measured value of the anemometer exceeded the standard value of the operation control. (3) Change of the standard wind speed for the operation control from the average wind speed to the instantaneous wind speed. (4) Establishment of regulations on the inspection and the maintenance of anemometers. In addition, the meeting put together the measures etc., against strong wind that could be implemented urgently in view of software and hardware, on September 12, 2006, and prescribed the guidance for the wind observation and the guidance for the windbreak facilities, in addition to prescribed the newly installation of the anemometers as the item of the measures. The meeting decided to continue the studies on the operation control and the measures against strong wind and put together the installation plan of the anemometers on December 19, 2006.

6.3. Measures Taken by the Japan Meteorological Agency The JMA promoted the installation of the Doppler radar monitoring the cumulonimbus clouds that had the possibilities to cause the tornado, etc., and started the observation of the instantaneous wind speed, that had been restricted in the District Observatories, in some AmeDAS observing station on March 25, 2008.

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The JMA decided to start the publication of the tornado advisory information from March 26, 2008, to secure the safety of the lives against the violent gust of wind such as the tornado, the down burst, etc., as the results of the studies in the "Study Meeting on Effective Use of the Information of Short Time Prediction of the Gust of Wind etc.", on the contents of the information, form of the presentation. methods of transmission, methods of utilization etc., based on the enrichment of these observation system. The tornado advisory information was the weather information, that report promptly the status at that moment as the cumulonimbus clouds to cause the violent dust of wind, i.e., the tornado, the down burst, etc., are easy to exist in that moment. It is prescribed to transmit the information to the disaster prevention organization and the press and list up in the home page of the JMA, as the information to complement the thunder advisory. Here, the JMA decided to publish the "Short Time Predicting Information on Gust of Wind etc.", predicting the dangerous area for each precise lattice area, from 2010 fiscal year.

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Attached Materials

Attached Figure 1. Route map of Uetsu Line ...... A1 Attached Figure 2. Topographical Map in around the Accident Site...... A2 Attached Figure 3. Schematic Diagram of around the Accident Site I ...... A3 Attached Figure 3. Schematic Diagram of around the Accident Site II ...... A4 Attached Figure 4. Boarded Positions of the Passengers, etc...... A5 Attached Figure 5. Status of Injuries of the Answered Injured Persons I ...... A6 Attached Figure 5. Status of Injuries of the Answered Injured Persons II ...... A6 Attached Figure 6. Status of Movement of Passengers due to Impact of the Accident ...... A7 Attached Figure 7. Rough Sketch of Damaged Status of the Facilities ...... A8 Attached Figure 8. Damages etc., of the Railway Facilities ...... A9 Attached Figure 9. Relationship between Traces on Rail and Wheels ...... A13 Attached Figure 10. Damages etc., of the Electricity Related Facilities ...... A14 Attached Figure 11. Damaged Status of the Vehicles I [1st Vehicle] ...... A15 Attached Figure 11. Damaged Status of the Vehicles II [2nd Vehicle] ...... A18 Attached Figure 11. Damaged Status of the Vehicles III [3rd Vehicle] ...... A20 Attached Figure 11. Damaged Status of the Vehicles IV [4rth Vehicle] ...... A22 Attached Figure 11. Damaged Status of the Vehicles V [5th and 6th Vehicles] ...... A24 Attached Figure 12. Damages in the Objects except for Railway Facilities and Vehicles ...... A25 Attached Figure 13. Process of the Train Operation ...... A26 Attached Figure 14. Composition and Indicators of the PreDAS ...... A27 Attached Figure 15. Track Irregularities before and after the Accident ...... A28 Attached Figure 16. Diagram for the Vehicle Types etc...... A29 Attached Figure 17. Ground Weather Map for Asian Pacific ...... A32 Attached Figure 18. Image of the Geostationary Meteorological Satellite ...... A33 Attached Figure 19. Time History of Observed Records in Sakata Observatory on the Accident Day ...... A34 Attached Figure 20. Wind Direction and Wind Speed in the AMEDAS at the Accident Time ... A35 Attached Figure 21. The Maximum Instantaneous Wind Speed at the Observing Point I ...... A36 Attached Figure 21. The Maximum Instantaneous Wind Speed at the Observing Point II ...... A37 Attached Figure 22. Maximum Wind Speed at the Observing Points I ...... A38 Attached Figure 22. Maximum Wind Speed at the Observing Points II ...... A39 Attached Figure23. Observed Records of Wind Speed at the No.2 Mogamigawa Bridge on the Accident Day ...... A40 Attached Figure 24. Intensity Distribution of Rader Echo and Vertical Section at the Accident . A41 Attached Figure 25. Damages by Strong Wind and Movement of Rader Echo I ...... A42 Attached Figure 25. Damages by Strong Wind and Movement of Rader Echo II ...... A43 Attached Figure 25. Damages by Strong Wind and Movement of Rader Echo III ...... A44 Attached Figure 25. Damages by Strong Wind and Movement of Rader Echo IV ...... A45 Attached Figure 25. Damages by Strong Wind and Movement of Rader Echo V ...... A46 Attached Figure 25. Damages by Strong Wind and Movement of Rader Echo VI ...... A47 Attached Figure 26. Observed Wind Profiler in Sakata Observatory on the Accident Day ...... A48 Attached Figure 27. Distribution of Damages by Strong Wind ...... A49 Attached Figure 28. Damaged Status in Hamanaka and Kuromori Area ...... A50 Attached Figure 29. Collapsed Wooden Windbreak Fence in Hamanaka Area ...... A51 Attached Figure 30. Fallen Trees in the Windbreak Forest in Hamanaka and Kuromori Area .... A52 Attached Figure 31. Damaged Status of Vinyl Houses in Kuromori Area ...... A53 Attached Figure 32. Damage of Windbreak Fence along National Highway 7 in Hirono Area I . A54 Attached Figure 32. Damage of Windbreak Fence along National Highway 7 in Hirono Area II ...... A55 Attached Figure 33. Collapsed Shed for Agricultural Machinery in Enoki Area I ...... A56

i Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 33. Collapsed Agricultural Machinery House in Enoki Area II ...... A57 Attached Figure 34. Installed Status of the Additional Anemometer ...... A58 Attached Figure 35. Observing Points for Wind in around the Accident Site ...... A59 Attached Figure 36. Plane View of the Large Scale Low Noise Wind Tunnel ...... A60 Attached Figure 37. Measuring Test for Aerodynamic Force etc...... A60 Attached Figure 38. The Vehicle Model and Six-Component Balance ...... A61 Attached Figure 39. Layout of Turbulent Boundary Layer Creating Device ...... A61 Attached Figure 40. Turbulent Boundary Layer Creating Device ...... A62 Attached Figure 41. Measuring Points of Wind Speed ...... A62 Attached Figure 42. Wind Speed Distribution of the Created Turbulent Boundary Layer, Measuring Line B ...... A63 Attached Figure 43. Aerodynamic Forces etc., acting on the Vehicle and Coordinate System .... A63 Attached Figure 44. Relationships between Aerodynamic Coefficient etc., and Angle of Wind Direction ...... A64 Attached Figure 45. Calculation Model for Critical Wind Speed of Overturning ...... A65 Attached Figure 46. Model for Suspension System of Vehicle ...... A65 Attached Figure 47. Wind acting on the Running Vehicle ...... A66 Attached Figure 48. Relationship between the Direction of Natural Wind and the Critical Wind Speed of Overturning I. The first vehicle...... A67 Attached Figure 48. Relationship between the Direction of Natural Wind and the Critical Wind Speed of Overturning II, The second vehicle...... A67 Attached Figure 49. Relationship between Running Velocity and the Critical Wind Speed of Overturning I, The first vehicle ...... A68 Attached Figure 49. Relationship between Running Velocity and the Critical Wind Speed of Overturning II, The second vehicle ...... A68 Attached Figure 50. Image of the Analysis on the Occurrence of the Vehicle Derailment ...... A69

ii Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 1. Route map of Uetsu Line

Uetsu Line connected Niitsu station and Akita station, 271.7 km business mile, by the single and double track.

1 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 2. Topographical Map in around the Accident Site

2 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 3. Schematic Diagram of around the Accident Site I

3 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 3. Schematic Diagram of around the Accident Site IIl

4 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 4. Boarded Positions of the Passengers, etc.

5 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 5. Status of Injuries of the Answered Injured Persons I Unit : Person Category of Answered Status at train stopped 1st 2nd 3rd 4th 5th 6th Total injuries injured persons Bone fracture 0 1 0 0 0 0 1

In the same position as Whiplash 0 0 0 0 0 1 1 4(1) before the accident Contusion 1 1 0(1) 0 0 0 2(1) Others 1 1 0 0 0 2 4 Bone fracture 3 2 0 0 0 0 5

In the different position Whiplash 0 0 0 0 0 0 0 7 as before the accident Contusion 2 2 1 0 0 0 5 Others 9 3 0 0 0 0 12 Bone fracture 0 1 0 0 0 0 1

Position was unknown Whiplash 0 1 0 0 0 0 1 6 when the train stopped Contusion 1 3 1 0 0 0 5 Others 4 3 2 0 0 0 9 * Based on inquiries by questionnaires implemented on September 2007. * Numbers in round brackets are the passengers standing when the accident occurred, counted separately. * When a passenger injured different kinds of injuries, counted as the different injuries.

Attached Figure 5. Status of Injuries of the Answered Injured Persons II Unit : Person Category of Answered 1st 2nd 3rd 4th 5th 6th Total injuries injured persons Bone fracture 0 3 0 0 0 0 3 Whiplash 0 0 0 0 0 0 0 Hold something 5(1) Contusion 1 3 1(1) 0 0 0 5(1) Others 1 5 2 0 0 0 8 Bone fracture 0 0 0 0 0 0 0 Whiplash 0 1 0 0 0 0 1 Protect my head 2 Contusion 0 1 1 0 0 0 2 Others 0 0 0 0 0 0 0 Bone fracture 3 1 0 0 0 0 4 Whiplash 0 0 0 0 0 1 1 Could not do anything 10 Contusion 3 2 0 0 0 0 5 Others 13 2 0 0 0 2 17 * Based on inquiries by questionnaires implemented on September 2007. * Numbers in round brackets are the passengers standing when the accident occurred, counted separately. * When a passenger injured different kinds of injuries, counted as the different injuries.

6 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 6. Status of Movement of Passengers due to Impact of the Accident

7 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 7. Rough Sketch of Damaged Status of the Facilities

8 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 8. Damages etc., of the Railway Facilities [1/4]

9 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 8. Damages etc., of the Railway Facilities [2/4]

10 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 8. Damages etc., of the Railway Facilities [3/4]

11 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 8. Damages etc., of the Railway Facilities [4/4]

12 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 9. Relationship between Traces on Rail and Wheels (1) Study on the trace in inside gauge of left rail in the section before the underbridge

It is probable that left wheel derailed at the position shown in the figure and damaged spring clips of rail fastening devices and sleepers, because there were broken spring clips as to be crushed or deformed heads of the fastening bolts in the rail fastening devices and lacks in the surfaces of the sleepers.

(2) Study on the traces in around the start edge of the underbridge

It is probable that the traces on the concrete blocks were caused by left wheels because there was no trace on the gratings of the underbridg.

(3) Study on the traces on the abutment concrete blocks in the end edge of the underbridge

It is probable that the traces in outside gauge were caused by left wheels because there was no trace on the gratings of the underbridg.

13 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 10. Damages etc., of the Electricity Related Facilities

14 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 11. Damaged Status of the Vehicles I [1st vehicle, 1 of 3]

15 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 11. Damaged Status of the Vehicles I [1st vehicle, 2 of 3]

16 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 11. Damaged Status of the Vehicles I [1st vehicle, 3 of 3]

17 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 11. Damaged Status of the Vehicles II [2nd vehicle, 1 of 2]

18 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 11. Damaged Status of the Vehicles II [2nd vehicle, 2 of 2]

19 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 11. Damaged Status of the Vehicles III [3rd vehicle, 1 of 2]

20 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 11. Damaged Status of the Vehicles III [3rd vehicle, 2 of 2]

21 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 11. Damaged Status of the Vehicles IV [4th vehicle, 1 of 2]

22 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 11. Damaged Status of the Vehicles IV [4th vehicle, 2o of 2]

23 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 11. Damaged Status of the Vehicles V [5th and 6th vehicles]

24 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 12. Damages in the Objects Except for Railway Facilities and Vehicles

25 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 13. Process of the Train Operation

26 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 14. Composition and Indicators of the PreDAS

Image of composition of the PreDAS

Image of the display in the operation control

27 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 15. Track Irregularities before and after the Accident

28 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 16. Diagram for the Vehicle Types etc. [1/3]

29 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 16. Diagram for the Vehicle Types etc. [2/3]

Major specifications, etc. Vehicle in train set 1st 2nd 3rd 4th 5th 6th Ku Ha Mo Ha Mo Ha Mo Ha Mo Ha Ku Ro Ha Symbol & number 481-3506 485-3018 484-3018 485-3044 484-3044 481-3010 Newly produced date April, 1974 April, 1974 April, 1974 April, 1974 April, 1974 April, 1974 Remodeled date Dec., 2000 Dec., 2000 Dec., 2000 Dec., 2000 Dec., 2000 Dec., 2000 Tare [t] 42.4 40.7 48.4 44.1 49.6 44.5 Capacity [Person] 64 72 64 72 58 52 Vehicle length [m] 21.250 20.500 20.500 20.500 20.500 21.250 Vehicle height [m] 3.475 3.475 3.475 3.475 3.475 3.475 Height of folded 4.241 4.241 pantograph [m] Vehicle width [m] 2.949 2.949 2.949 2.949 2.949 2.949

30 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 16. Diagram for the Vehicle Types etc. [3/3]

31 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 17. Ground Weather Map for Asian Pacific

15:00, December 25, 2005

21:00, December 25, 2005

Revised the material provided from the JMA

32 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 18. Image of the Geostationary Meteorological Satellite

33 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 19. Time History of Observed Records in Sakata Observatory on the accident day

34 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 20. Wind Direction and Wind Speed in the AMEDAS at the accident time

35 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 21. The Maximum Instantaneous Wind Speed at the Observing Point [1/2] [From 18:30 to 19:30]

36 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 21. The Maximum Instantaneous Wind Speed at the Observing Point [2/2] [From 18:30 to 19:30]

Weather observing point Maximum instantaneous Time of Installed height of Remarks wind velocity [m/s] observation, anemometer [m] round up subsecond JMA Sakata weather station WSW 21.6 19:12 27.5 Shonai airport WSW 23.2 19:24 10 Sakata river and national highway office, MLIT Miyanoura WNW 23.1 18:54 5.15 *1 Shinkawa beach S 36.9 19:07 8 *1 Hamanaka SSW 22.5 19:09 10 Up stream of Shinkawa SW About 20.5 About 19:10 7.8 *1 Drainage No.10 WNE About 15 About 19:10 6 *1*2*3 Amarume snow removal ST W 18.0 19:30 About 10 Hirota IC SW 21.7 19:00 About 10 Obako bridge W 24.7 19:30 About 10 Sakata harbor office, MLIT Sakata harbor office WNW 22.6 19:10 to 20 14.1 *1 Hokko office W About 24 About 19:05 About 13 *1*2 Hirata General Branch, Sakata City Asuka W 14.5 19:19 About 10 *1 Yamahashi ESE 3.5 19:13 About 10 *1 Tazawa WNW 18.7 19:21 About 10 *1 Sakata district fire association Fire association W 24.6 19 to 20 Hr. 17 Sakata District Clean Association Clean aasociation WSW 17.2 19:11 About 33 Tohoku Branch, East Japan Highway Company No.2 Mogamigawa bridge, Unknown 21 19:27 to 30 About 6.5 Existing anemometer

*1 Observed data that was measured by the device without official approval or the expired period of validity. *2 The rough estimated value that was obtained by reading visually the recorded data printed in the recording paper. *3 There was a possibility that the environment around observing point had affected to the observed values.

37 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 22. Maximum Wind Speed at the Observing Points I [ From 18:30 to 19:30 ]

38 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 22. Maximum Wind Speed at the Observing Points II [From 18:30 to 19:30 ]

Weather observing point Maximum instantaneous Time of Installed height of Remarks wind velocity [m/s] obserbation anemometer [m] JMA Sakata weather station SW 11.4 18:30 27.5 Shonai airport WSW 15.0 19:30 10 Karikawa SSW 5 19:20 6.5 Sakata river and national highway office, MLIT Miyanoura WNW 16.2 19:16 5.15 *1 Shinkawa beach SW 18.3 19:09 8 *1 Hamanaka SW About 10.5 About 19:15 10 *2 Sakata harbor office, MLIT Sakata harbor office WNW 13.2 19:20 14.1 *1 Hokko office WNW About 17 About 19:05 About 13 *1*2 Off Sakata WNW 19.9 18:50 19.2 Culture & environment dept., Yamagata Prefecture Sakata inversion layer WNW About 13 About 19:00 10 *1 Sakata Wakahama W About 11 About 19:20 13 *1*2 Sakata Hikarigaoka SSW About 4.5 About 18:30 6 *1*2 Sakata Ueda W About 13.5 About 19:20 7 *1*2 Amarume W About 4 About 19:30 6 *1*2 Citizen live Dept., Sakata City Nishi Arase WNW About 7.5 About 19:10 6.0 above sea level *1*2 11.0 above sea Hiyoriyama SSW About 11 About 18:50 *1*2 level Nishiki Machi WNW About 6.5 About 19:20 3.0 above sea level *1*2 Hirata General Branch, Sakata City Asuka WNW 6.8 19:20 About 10 *1 Yamahashi ESE 2.7 19:20 About 10 *1 Tazawa WNW 8.8 19:30 About 10 *1 Sakata district fire association Fire association WNW 15.6 19:15 17 Tohoku Branch, East Japan Highway Company Shiratori Bridge, Mogami river WSW 13.2 19:22 4.5

Kuromori-Akagawa bridge W 12.0 19:15 4.5 *1 Eco Power Company The 6th power station Unknown 7.6 19:13 About 46.5 *1

*1 Observed data that was measured by the device without official approval or the expired period of validity. *2 The rough estimated value that was obtained by reading visually the recorded data printed in the recording paper.

39 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure23. Observed Records of Wind Speed at the No.2 Mogamigawa Bridge on the Accident Day [ Observed data by the existed anemometer ]

* The observed wind speed was estimated to pick up the maximum value in the past 3 minutes from the wind speed measured every 0.5 second and hold the value for 3 minutes in the observation system. Here, when the wind speed reached to the standard vale was observed for the first time, the holding value was changed by the interrupting signal.

40 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 24. Intensity Distribution of Rader Echo and Vertical Section at the Accident

41 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 25. Damages by Strong Wind and Movement of Rader Echo I [ Observed about 19:05:20 ]

42 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 25. Damages by Strong Wind and Movement of Rader Echo II [ Observed about 19:05:50 ]

43 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 25. Damages by Strong Wind and Movement of Rader Echo III [ Observed about 19:06:20 ]

44 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 25. Damages by Strong Wind and Movement of Rader Echo IV [ Observed about 19:14:20 ]

45 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 25. Damages by Strong Wind and Movement of Rader Echo V [ Observed about 19:14:50 ]

46 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 25. Damages by Strong Wind and Movement of Rader Echo VI [ Observed about 19:15:20 ]

47 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 26. Observed Wind Profiler in Sakata Observatory on the Accident Day

48 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 27. Distribution of Damages by Strong Wind

49 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 28. Damaged Status in Hamanaka and Kuromori Area

50 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 29. Collapsed Wooden Windbreak Fence in Hamanaka Area

51 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 30. Fallen Trees in the Windbreak Forest in Hamanaka and Kuromori Area

52 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 31. Damaged Status of Vinyl Houses in Kuromori Area

53 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 32. Damage of Windbreak Fence along National Highway 7 in Hirono Area I

54 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 32. Damage of Windbreak Fence along National Highway 7 in Hirono Area II [ From west of the road ]

55 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 33. Collapsed Shed for Agricultural Machinery in Enoki Area I

56 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 33. Collapsed Agricultural Machinery House in Enoki Area II

57 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 34. Installed Status of the Additional Anemometer

Photo 1. Additional anemometers in Akita station side of the concerned bridge [ Existed anemometer of the company was installed in the center]

Photo 2. Additional anemometers in around the accident site

58 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 35. Observing Points for Wind in around the Accident Site

59 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 36. Plane View of the Large Scale Low Noise Wind Tunnel

Attached Figure 37. Measuring Test for Aerodynamic Force etc.

Photo. Status of measuring test for aerodynamic forces etc.

60 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 38. The Vehicle Model and Six-Component Balance

Attached Figure 39. Layout of Turbulent Boundary Layer Creating Device

61 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 40. Turbulent Boundary Layer Creating Device

Attached Figure 41. Measuring Points of Wind Speed

Measur- Height Measur- Height Measu- Height ing from RL ing from RL ring from RL point [m] point [m] point [m] a1 15.2 b1 15.2 d1 15.2 Measur- Measur- Measur- a2 10.0 b2 10.15 d2 10.0 ing line ing line ing line a3 5.0 b3 5.0 d3 5.0 a b d a4 2.5 b4 0 d4 2.5 * RL : Rail level.

62 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 42. Wind Speed Distribution of the Created Turbulent Boundary Layer, Measuring Line B

Attached Figure 43. Aerodynamic Forces etc., Acting on the Vehicle and Coordinate System

Coefficient of lateral force F C = S S 1 2 2 U S Coefficient of lift force F C = L L 1 2 2 U S Coefficient of moment M C = M 1 2 2 U ShB

β : Angle of wind direction refer to vehicle

F s : Lateral force

F : Lift force L M : Rolling moment ρ : Air density ( 1.23 kg/m3 ) U : Standard wind speed l ; Length of the vehicle body

hS : Height of the vehicle body S : Area of side surface of the vehicle

63 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 44. Relationships between Aerodynamic Coefficient etc., and Angle of Wind Direction

64 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 45. Calculation Model for Critical Wind Speed of Overturning

CA : Center of the wind pressure GB : Gravity center of the vehicle body GT : Gravity center of the bogie FSA : Lateral force caused by a side wind FLA : Lift force caused by a side wind mB : Mass of the half vehicle body hBC : Height of the center of wind pressure hGB : Height of the gravity center of vehicle body e : Distance between CA and GB mT : Mass of the bogie αy : Acceleration of lateral vibration of vehicle body g : Acceleration of the gravity hGT : Height of the gravity enter of the bogie PR : Wheel load of right wheel PL : Wheel load of left wheel yB : Lateral displacement of GB φB : Roll displacement of GB G : Distance between contacted points of wheel and rail 1 Lateral force F = C u 2 S SA 2 S A 1 Lift force F = C u 2 S LA 2 L A C Height of center of air pressure M hBC = hb1 + hB C S ρ : Air density (1.23 kg/m3) hB1 : Height of vehicle body center[m] u : Wind speed [m/s] hB : Height of vehicle body [m] 2 SA : Side surface area of half vehicle body [m ]

Attached Figure 46. Model for Suspension System of Vehicle

C : Vehicle body center, i.e., the point at the half height of the vehicle body GB : Gravity center of vehicle body GT : Gravity center of bogie hGB : Height of gravity center of vehicle body hGT : Height of gravity center of bogie hB1 : Height of vehicle body center hB : Height of vehicle body hKC : Height of center of secondary spring hSC : Height of lateral displacement stopper yS : Gap of lateral displacement stopper zS : Gap of vertical displacement stopper G : Distance between contacted points of wheel and rail 2b1 : Distance between centers of left and right axle spring 2b2 : Distance between centers of left and right secondary spring 2bS : Distance between centers of left and right vertical displacement stoppers

65 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 47. Wind acting on the Running Vehicle

w : Wind speed vector of natural wind, critical wind speed of overturning α : Angle of wind direction of natural wind u : Wind speed vector refer to the vehicle β : Angle of wind direction refer to the vehicle v : Velocity vector of running train

66 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 48. Relationship between the direction of Natural Wind and the Critical Wind Speed of Overturning I, The first vehicle.

Attached Figure 48. Relationship between the direction of Natural Wind and the Critical Wind Speed of Overturning II, The second vehicle.

67 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 49. Relationship between Running Velocity and the Critical Wind Speed of Overturning I, The first vehicle.

Attached Figure 49. Relationship between Running Velocity and the Critical Wind Speed of Overturning II, The second vehicle.

68 Translated by T. A. Lab., Inc., Japan, Sept., 2019

Attached Figure 50. Image of the Analysis on the Occurrence of the Vehicle Derailment

69 Translated by T. A. Lab., Inc., Japan, Sept., 2019

70