Alaska Department of Transportation & Public Facilities
Evaluation of Track Circuits Through Whittier Tunnel
Prepared By: Bill Wiedmann Bert Wescott
April 2013
Prepared For:
Alaska Department of Transportation & Public Facilities Research, Development, and Technology Transfer 2301 Peger Road Fairbanks, AK 99709-5399
FHWA-AK-RD-13-12
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FHWA-AK-RD-13-12 April 2013 FINAL 09/2012 to 04/2013
4. TITLE AND SUBTITLE 5. FUNDING NUMBERS
Evaluation of Track Circuits Through Whittier Tunnel AKSAS #61862/T2-12-07 Federal # RI-4000(116)
6. AUTHOR(S)
Bill Wiedmann, Bert Wescott
7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION REPORT NUMBER The Burns Group Engineering and Construction 1835 Market Street FHWA-AK-RD-13-12 Philadelphia, PA 19103
9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSORING/MONITORING AGENCY REPORT NUMBER Alaska Department of Transportation and Public Facilities Research, Development &Technology Transfer FHWA-AK-RD-13-12 2301 Peger Rd Fairbanks, AK 99709-5399
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13. ABSTRACT (Maximum 200 words)
The Alaska Department of Transportation and Public Facilities (Alaska DOT&PF) in cooperation with the Alaska Railroad (AKRR) is seeking viable mitigation strategies for the progressive failure of the track circuits traversing the Anton Anderson Memorial Tunnel, better known as the Whittier Tunnel. This report documents our findings and proposed mitigation measures and includes: • Narrative on the field evaluation of the existing track bed and track circuit systems used to determine the causes for the track circuit failures, • Alternative solutions for modifying the existing track circuit system including, but not limited to modifying the rail bed, and/or using axle counters, • Budgetary cost estimates for the alternatives developed.
15. NUMBER OF PAGES 14. KEYWORDS : Tunnels (Pdvt), Automatic train location (Dmbyc), Track panels (Pmudbv), Automatic train control (Dcmvgyf) 16. PRICE CODE
N/A 17. SECURITY CLASSIFICATION OF 18. SECURITY CLASSIFICATION 19. SECURITY CLASSIFICATION 20. LIMITATION OF ABSTRACT REPORT OF THIS PAGE OF ABSTRACT
Unclassified Unclassified Unclassified N/A
NSN 7540-01-280-5500 STANDARD FORM 298 (Rev. 2-98) Prescribed by ANSI Std. 239-18 298-102
SI* (MODERN METRIC) CONVERSION FACTORS APPROXIMATE CONVERSIONS TO SI UNITS Symbol When You Know Multiply By To Find Symbol LENGTH in inches 25.4 millimeters mm ft feet 0.305 meters m yd yards 0.914 meters m mi miles 1.61 kilometers km AREA in2 square inches 645.2 square millimeters mm2 ft2 square feet 0.093 square meters m2 yd2 square yard 0.836 square meters m2 ac acres 0.405 hectares ha mi2 square miles 2.59 square kilometers km2 VOLUME fl oz fluid ounces 29.57 milliliters mL gal gallons 3.785 liters L ft3 cubic feet 0.028 cubic meters m3 yd3 cubic yards 0.765 cubic meters m3 NOTE: volumes greater than 1000 L shall be shown in m3 MASS oz ounces 28.35 grams g lb pounds 0.454 kilograms kg T short tons (2000 lb) 0.907 megagrams (or "metric ton") Mg (or "t") TEMPERATURE (exact degrees) oF Fahrenheit 5 (F-32)/9 Celsius oC or (F-32)/1.8 ILLUMINATION fc foot-candles 10.76 lux lx fl foot-Lamberts 3.426 candela/m2 cd/m2 FORCE and PRESSURE or STRESS lbf poundforce 4.45 newtons N lbf/in2 poundforce per square inch 6.89 kilopascals kPa APPROXIMATE CONVERSIONS FROM SI UNITS Symbol When You Know Multiply By To Find Symbol LENGTH mm millimeters 0.039 inches in m meters 3.28 feet ft m meters 1.09 yards yd km kilometers 0.621 miles mi AREA mm2 square millimeters 0.0016 square inches in2 m2 square meters 10.764 square feet ft2 m2 square meters 1.195 square yards yd2 ha hectares 2.47 acres ac km2 square kilometers 0.386 square miles mi2 VOLUME mL milliliters 0.034 fluid ounces fl oz L liters 0.264 gallons gal m3 cubic meters 35.314 cubic feet ft3 m3 cubic meters 1.307 cubic yards yd3 MASS g grams 0.035 ounces oz kg kilograms 2.202 pounds lb Mg (or "t") megagrams (or "metric ton") 1.103 short tons (2000 lb) T TEMPERATURE (exact degrees) oC Celsius 1.8C+32 Fahrenheit oF ILLUMINATION lx lux 0.0929 foot-candles fc cd/m2 candela/m2 0.2919 foot-Lamberts fl FORCE and PRESSURE or STRESS N newtons 0.225 poundforce lbf kPa kilopascals 0.145 poundforce per square inch lbf/in2
*SI is the symbol for the International System of Units. Appropriate rounding should be made to comply with Section 4 of ASTM E380. (Revised March 2003)
Evaluation of Track Circuits Through Whittier Tunnel
Contents Overview ...... 4 Purpose ...... 4 Historical ...... 4 Construction ...... 5 Tunnel Operation ...... 6 Tunnel Signal System (TSS) ...... 7 The Problem ...... 9 Track Circuit ...... 10 Ballast Resistance ...... 11 Shunting ...... 14 Broken Rail Protection ...... 14 Condition of Tunnel Roadway and Rail ...... 15 Summary of rail observations ...... 15 Summary of panel observations ...... 15 Cracks ...... 15 Surface Deterioration...... 16 Joints ...... 17 Settled panels...... 18 Rubber Rail Seal ...... 18 Pandrol® Clips and Other Track Material (OTM) ...... 19 Water Issues ...... 19 Track Circuit Overview ...... 20 Track Circuit 1OST ...... 21 Whittier to Safe House #4, 1OST Tra ...... 21 Track Circuit 2OST ...... 23 Safe House #4 to Bear Valley, 2OST Track ...... 23 Safe House #4 Insulated Joint Location ...... 23 Insulated Joints Separating 1OST and 2OST ...... 23 Conclusions ...... 28
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Recommendations ...... 29 Recommendation 1 - Axle Counters ...... 29 Recommendation 2 – A More Robust Track Circuit ...... 32 Recommendation 3 –Polymeric Encasement or Rubber Boot Around the Rail ...... 34 Immediate Remediation Initiatives ...... 36 APPENDIX I ...... 37 LIST OF CRACKED PANELS ...... 37 APPENDIX II ...... 39 LIST OF PANELS WITH SURFACE DETERIORATION ...... 39 APPENDIX III ...... 41 LOCATIONS OF PANELS WITH MISSING SEALANT ...... 41 ROUGH ORDER OF MAGNITUDE COST BREAKDOWN ...... 42 Axle Counter Installation ...... 42 Replace E-Code with MicroTrax Track Circuit ...... 43 Rail Encasement ...... 44
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Overview
Purpose The Alaska Department of Transportation and Public Facilities (Alaska DOT&PF) in cooperation with the Alaska Railroad (AKRR) is seeking viable mitigation strategies for the progressive failure of the track circuits traversing the Anton Anderson Memorial Tunnel, better known as the Whittier Tunnel. This report documents our findings and proposed mitigation measures and includes:
• Narrative on the field evaluation of the existing track bed and track circuit systems used to determine the causes for the track circuit failures, • Alternative solutions for modifying the existing track circuit system including, but not limited to modifying the rail bed, and/or using axle counters, • Budgetary cost estimates for the alternatives developed.
On September 9, 2012, the Alaska Department of Transportation awarded a research project to Burns Engineering to evaluate the apparent progressive track failure of the track circuit system in the Anton Anderson Memorial Tunnel, better known as the Whittier Tunnel.
On October 8, 9 and 10, 2012, Burns Engineering performed visual observations on the embedded track system that runs through Whittier Tunnel. The purpose of the observations was to assess the condition of the embedded track system and to determine if its condition is a contributing factor to the problems that Alaska Railroad (AKRR) is experiencing with the track circuit based signal system. While doing the track observations, there were simultaneous investigations of the signal system (by Burns Engineering), the tunnel drainage system (by AKDOT) and the subgrade, which was performed using ground- penetrating radar (GPR) also by AKDOT. Follow-on research looked at various ways of re-establishing electrical isolation between the rails and ground.
Historical The Whittier tunnel was constructed in 1941-1943 through Maynard Mountain to provide rail service that moved goods from the deep water, ice free port of Whittier, to Alaska’s largest city, Anchorage. The tunnel was constructed as a single track where direction of travel was controlled by railroad operating procedures. To allow residents access to and from Whittier, a method for transporting automobiles and trucks through the tunnel was devised by the Alaska Railroad by which the cars and trucks were driven onto flatcars, pulled through the tunnel and off-loaded on the other side. By 1992, the Alaska DOT was searching for ways to streamline this process. After evaluating numerous proposals, the most cost effective and efficient recommendation was to convert the tunnel into a mixed use facility with trains or automobiles provided access to the tunnel in a single direction at any given time. The Whittier Tunnel is the longest mixed use tunnel in North America at approximately 2.6 miles.
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Construction In 2001, the invert of Whittier Tunnel was rebuilt with Star Track® concrete modules, or panels, creating a 2.6-mile long embedded track. Star Track®, a modular pre-cast concrete grade-crossing system produced by Oldcastle Precast, has been used to build embedded track at other port facilities and at numerous grade crossings.
The Star Track® system selected for the Whittier Tunnel is comprised of pre-cast concrete panels that are 8 feet wide (across the track) and 7.5 feet long (along the track). The pre-cast panels are cast with slots for running rails. Pandrol® e-clips, hooked into shoulders cast into the bottom of the slots, are used for rail fixation. Electrical isolation of the running rails from the concrete panel is achieved by installing a 3/16-inch thick continuous polyethylene pad between the base of the rail and the concrete and by inserting nylon insulators between the e-clip and the flange of the rail.
Figure 1. Star Track Panel
In a typical highway grade crossing installation, after the panels are placed and rail installed, the driving surface for automobile traffic is completed by placing PPI Rubber Inserts® into the field side and gage side slots between the rail and concrete panel. At the Whittier Tunnel installation, the rubber inserts were used only at the first 52 feet at the Bear Valley Portal and at the first 54 feet at the Whittier Portal. In between, throughout the rest of the tunnel, geotextile was placed at the bottom of the slot to protect
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Evaluation of Track Circuits Through Whittier Tunnel the e-clips and the slots were filled with asphalt concrete. Construction was typically finalized by placing rubber joint gap filler strips in the joints between each panel.
The tunnel drainage system is comprised of a roadway drainage network and a perforated pipe sub- drain network. Slot drains at both edges of the roadway and drainage inlets collect water and route it to two corrugated steel roadway drainage pipes, one on each side of the tunnel. Ice control collectors at both entrances are also connected to the roadway drainage network. Below Figure 2. Sump Pump As Part Of The Tunnel Drainage System. the elevation of the roadway drainage pipes are 4-inch perforated sub-drain pipes. The sub-drain collects any water that collects in the filter stone along the edges of the roadway base layer. Cleanouts for both the roadway drainage pipes and the sub- drain pipes are located throughout the length of the tunnel. In profile, the tunnel is sloped from west to east. Consequently all water collected within the tunnel is discharged to a drainage ditch east of the Whittier Portal. Runoffm fro the roadway is prevented from entering the tunnel at the Bear Valley portal by a transverse slot drain.
Tunnel Operation Figure 3. Tunnel Operations Center The Whittier Tunnel is maintained by the Alaska Department of Transportation & Public Facilities (AkDOT&PF) with the Alaska
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Railroad supplying maintenance of the railroad equipment and circuitry through the tunnel. The tunnel operates on a schedule for automobile traffic with approximately 15 minute openings for traffic in each direction approximately every hour. Vehicles waiting to proceed through the tunnel are held at the respective staging area on either side of the tunnel. At the staging area the motorist will observe red traffic lights and horizontal highway crossing gates across the approach to the tunnel entrance. To release vehicular traffic into the tunnel, the tunnel operator ensures that the tunnel is clear of all traffic and proceeds to call for traffic in an east or westward direction. Provided the train signal system reports the tunnel is unoccupied by a train and a signal is not cleared for a train, and the opposing auto traffic gate is closed, the tunnel will be deemed safe to traverse for vehicular traffic. At that time, the crossing gates will rise and the traffic signals will turn green. At the end of the scheduled period, the operator will restore the signals to red and the gates will again drop across the road. Most trains that pass through the tunnel are short term scheduled with only a few hours’ notice prior to their arrival. When a train arrives, auto traffic will be halted to give the train priority. Signals, to allow a train to proceed, cannot be displayed until the tunnel operator gives a “Tunnel Safe” indication to the Train Signal System. “Tunnel Safe” means that there is no vehicular traffic in the tunnel, all traffic lights are red and the crossing gates on both ends of the tunnel approaches are in the horizontal position. Once the train proceeds onto the approach tunnel tracks, track circuits monitor its progress through the tunnel. The tunnel cannot resume operation for vehicular traffic until the two track circuits spanning the tunnel report that the track is clear.
Tunnel Signal System (TSS) The TSS as originally installed during construction was a very simple and singular system designed to keep rail traffic and highway traffic apart. To accomplish this task, the system had to have a method of conveying exclusive authority to either the Alaska Railroad, or to the DOT. Because the tunnel does not allow road traffic between approximately 11:00pm and 5:00am, the system had to have a means for after-hours access to meet the emergency needs of the City of Whittier. After-hours access was accomplished through a phone box on the gate islands in each staging area, and a button to raise and lower the doors. The phones allowed for direct communications with the Alaska Railroad dispatcher.
Initially, the train control system was a Harmon Industries track/interlock system. By 2002 the Alaska Railroad implemented changes to the system that eliminated the local blocking control located on each signal bungalow (Bear Valley and Whittier). Local blocking prevented the railroad dispatcher from clearing signals for trains into the tunnel. Thereafter, all after-hours access was through the railroad dispatcher only.
Around 2004, to accommodate their new Crash Avoidance System (CAS), the Alaska Railroad began to replace their existing Harmon equipment with material manufactured by Union Switch & Signal. The new system insures safe train separation for all trains operating on the AKRR system. To make the new system as economically responsible as possible, Alaska Railroad accommodated the new equipment by retaining some of the existing Harmon apparatus. In the tunnel, the track circuits became a hybrid with US&S equipment in the outlying control houses and Harmon equipment in Safe House #4.
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During 2011-2012 the AKRR completed the new signal system from the main line at Portage to Whittier. The new system fully integrated the TSS into the signal system. The new system involved moving the tunnel advance signal from mile F7.0 to mile F8.4, and creating an intermediate signal. The track circuit from the intermediate signal is immediately adjacent to the TSS circuit on the ARRC South and the Portage signal on the ARRC North.
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The Problem In recent years, the circuits that detect train occupancy in the tunnel have been experiencing a degradation of operational reliability. When either of the track circuits that run the length of the tunnel fails to operate properly, the default (fail-safe) state of the circuit is to indicate that the track is occupied. When this condition occurs, the tunnel operator cannot clear the traffic signals for vehicular traffic into the tunnel. This presents a difficult challenge for the tunnel operator as traffic will build in the staging areas to a critical mass. Furthermore, any trains that may need to pass through the tunnel will not be able to receive a proceed signal until the track circuits are restored. The Alaska Railroad, in response to the false occupancy failures, has sent out technicians to investigate. Their findings consistently indicated that the electrical conductivity of the track circuit was deteriorating along the rails. The remediation for this problem was to increase the power to the circuit in order to overcome the power dissipation through leakage current of the circuit. Presently, the upper limits of the track circuit module have been reached and can no longer be adjusted. Collectively, the railroad and Alaska DOT are concerned about further degradation of the track circuit.
In 2012, there were 35 false train requests that occurred during highway mode while highway traffic was in the tunnel. When a false request occurs, the TSS (Train Signal System) detects train occupancy and sends a request to the TSCS. Since the tunnel is in active highway mode, the TSCS signals the tunnel control operator that there is a train in the tunnel. Promptly, the system activates the highway gates across the road leading to the tunnel. Once the progression is initiated, the tunnel operator needs to override the highway gate operating sequence to prevent the gates from striking vehicular traffic. The tunnel is then scanned for rail vehicles, and finally a call to the Alaska Railroad dispatcher to verify that an ARRC request for an actual train move has not occurred. Once traffic is cleared, the railroad dispatcher and tunnel controller work through the scenario to clear the false request. This usually works 70% - 80% of the time. If this process fails to clear the false request, the railroad dispatcher will send a train request to the TSS and then cancel it. This strategy works nearly all the time on false requests when the tunnel is in highway mode.
Five times during 2012 the false train request occurred when the tunnel was in railroad mode. This type of train request (lock) occurs when a train has completed traveling through the tunnel, and the TCS has not detected if the train has exited the tunnel. In this case, the tunnel cannot be transferred back to highway mode. In this case, the tunnel control operator will request the railroad dispatcher to send another request for control of the tunnel which is quickly canceled. If this fails to clear the failure, the tunnel control operator will reboot the servers. If re-booting the servers still cannot clear the problem, the railroad signal crew will be required to proceed to the tunnel to override the system. Under a recently implemented procedure, the railroad dispatcher can give the tunnel control operator a command code which will override the false occupancy and reopen the tunnel to highway traffic.
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Track Circuit The American Railway Engineering & Maintenance of way Association (AREMA) defines a track circuit as “An electrical circuit which uses the track rails as the conductors between the transmit and receive devices, the limits of which are commonly defined by the location of insulated joints. The primary purpose of the track circuit is to detect an occupancy or interruption. It may also be used to convey information 1”. A track circuit in its most basic form uses a power supply to send current along the rails, using the rails as conductors, to pick up a track relay at the end of the block. The track relay attached to the rails is constantly energized by a closed loop circuit unless opened by an open wire, blown fuse, etc ., or by the axles of the train across the rails shunting the current away from the relay. In this way the track circuit is considered to be “fail safe” because any failure of the circuit will cause the relay to go to its most restrictive state.
The track circuits used in the Whittier Tunnel are commonly referred to as electronic coded track circuits. This type of track circuit can trace its ancestry to the coded direct current track circuits developed in the 1930’s. The original tunnel track circuits were manufactured by Harmon Industries (now GE Transportation) and consisted of Electro-Code 4 (EC4) modules. Although the EC4 is rated for a track circuit up to 15,000 ft., Alaska Railroad needed to upgrade to an EC5 which increased the available track circuit power to enable the track to extend to about 23,000 ft. The Ansaldo track circuits, which subsequently replaced the Harmon EC5 in the outside locations, were designed to be completely compatible with the Harmon system.
There are three track circuit locations utilized for Whittier Tunnel:
• A signal bungalow at Bear Valley on the west end of the tunnel which houses Ansaldo E-Code track modules • A wall mounted case outside of Safe House #4 containing GETS EC-5 • A signal bungalow at Whittier on the east end of the tunnel also with Ansaldo E-Code.
1 AREMA C&S Manual, Part 1.1.1
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Figure 4. Whittier Tunnel Track Circuits
At each of these locations the track circuit modules send and receive coded pulses through the rails. DC track I/O are used to inject and extract coded pulses on and off the tracks. The polarity and level of current must be correct before the receiver will respond. The codes are transmitted through the rails between insulated joints with the absence of a receive code at either end indicating track occupancy.
Ballast Resistance Track ballast forms the track bed upon which the railroad ties are laid. It is generally used to facilitate drainage of water, provide a cushioning base, and to keep the ties in place on the rail bed structure. Ballast is typically made of crushed stone, although ballast has sometimes consisted of other, less suitable materials. Ballast resistance is defined as the resistance between the two rails of a track circuit and comprises of leakage between the rail fixings, ties and earth. When the ballast is wet or contains substances such as salt or minerals that conduct electricity easily, current can flow from one rail to the other rail. Wet or contaminated ballast is considered to have low ballast resistance. With low ballast resistance, track circuit leakage current is high. When the ballast resistance decreases significantly, the track circuit can be robbed of its current and become de-energized, or fail to energize after a train shunt has been removed from the circuit. Because ballast resistance varies between a wet day (minimum ballast resistance) and a dry day (maximum ballast resistance) the flow of current from the power source may vary considerably.
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Ballast resistance is critical in the operation of track circuits because the resistance offered by the ballast, ties, etc., to the flow of leakage current from one rail of a track circuit to the other may negatively impact the reliability of the track circuit. The ties that secure the rails in place act as insulation between the two rails. This insulation is not perfect however, it has a resistance value that may affect the correct operation of the track circuit. Each contact point between tie and rail can be
Figure 5. Rails Encapsulated In Bitumen roughly equivalent to a 1000 ohm resistor between rails. When the ties and the ballast become wet, the insulation of the ties will decrease. Depending upon the adjustment of the track circuit power settings, wet track may decrease ballast resistance enough to cause the track circuit to fail. Conversely, should the track circuit become dry, the danger is that the track circuit could become over energized and fail to shunt under a train. Standard track design stresses the importance of maintaining a reasonable level of insulation between the rails and the ballast, dirt, sand, etc. The isolation of the rails from ballast helps to mitigate fluctuations in ballast resistance and prevent under or over energization of the track circuit. The rails in Whittier Tunnel are in constant contact with the bitumen fill around the rails which in effect provides infinite contact points for leakage current trying to flow through the rail.
Conditions inside the tunnel remain fairly constant over the course of the year with some minor variations due to the weather extremes on the exposed sections of track. Spring induces a significant increase in water, dripping from the tunnel crown and walls onto the invert surface, brought on by melting snow from the mountain. In some areas, the underlying ballast becomes saturated. This could potentially impact track circuit operation by causing electrical “lumps” in the ballast resistance. Otherwise, the majority of the track circuits are within the confines of the tunnel and, as such, ballast resistance remains fairly constant. The ballast resistance calculations of the track circuits in the tunnel were based upon four meter readings for each circuit. Voltage and current readings were taken using the E-Code transmitter as a steady feed (not coding) in one direction only (from the wayside bungalows
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at Whittier and Bear Valley). The adjacent track circuit to the one being tested was completely de- energized to insure that voltage was not passing through insulated joints and affecting circuit readings.
Ballast resistance may
be calculated by using the formula
Figure 6. Worn Bitumen and Sludge Contaminate where Rb = ballast resistance per 1,000 feet, Ef = voltage at the feed end rails, Er = voltage at the relay end rails, If = current at feed end, Ir = current at relay end and L = length of track circuit in 1,000 ft. In most cases, the minimum ballast resistance under worse case conditions should not be less than 2 ohms per 1,000 feet of track for track circuits longer than 4,000 feet in length2. Based upon actual readings taken at the Whittier and Bear
Track Circuit Current Flow
Figure 7. Track Circuit Current Flow Around A Broken Rail
2 American Railway Signaling Principles and Practices, Chapter 7, Non-Coded Direct Current Track Circuits
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Valley locations, the ballast resistance of the 1OST track circuit is approximately 1.2 ohms and 2OST is 1.94 ohms per 1,000 ft.
Shunting A train entering a track circuit effectively shorts out (shunts) the track circuit voltage from reaching the device that is used for indicating train occupancy. In an electronic coded track circuit, coded pulses are used to establish a hand shaking protocol between the ends of the circuit which alternately send and receive data in both directions. The coding protocol provides a vital method for the signal system to detect a train and to provide broken rail protection. Any disruption to the code or the loss of code will appear as track occupancy to the signal system. There are many different forms of contaminates that could affect the shunting reliability of the wheel/rail interface. Contaminates may include rust, sand, brake material, oil, water, soil or metal particles. The rails in Whittier Tunnel appear to support various contaminates on the railhead. Water, soil, sand and traces of oil appear to collect on the rail head. These elements seem to originate from various sources in the tunnel. Because the tunnel is mixed use, many of these contaminates may come from outside of the tunnel on trucks, cars and boats as they proceed through the 2.6 mile tunnel. At some locations, silt from under the concrete rail panels seems to have percolated up through the joints between the panels and infiltrated the railway. The bituminous asphalt used to fill the gap between the panels and the rails has begun to wear and combined with the constant water in sections has created a slightly petrol based sludge. The sludge residing in the flange way of the track provides additional leakage paths for track circuit current and could compromise the shunting efficiency of the track circuit. When mud/sludge lie on top of the rails, the ability of the track circuit to effectively detect rail traffic may also be jeopardized.
Broken Rail Protection The effectiveness of track circuits in detection of broken rails has been the subject of considerable discussion among signal engineers for years. It is generally believed that approximately half of the broken rail situations will be detected by the track circuit. In the case of Whittier Tunnel, the subject becomes almost inconsequential. The embedded track structure combined with the bituminous fill on both sides of the rail make the probability of a broken rail impacting railroad operations unlikely. The detection of the broken rail in the tunnel environment by a track circuit becomes even less likely again due to the bituminous fill and the flange way sludge surrounding the rails. The conductivity of the fill around the rails acts to mitigate the effects of the break on the track circuit. This is borne out by the fact that there have been two rail breaks in the tunnel to date with both detected by an ultrasound broken rail detector and not by the track circuit system.
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Condition of Tunnel Roadway and Rail Panel identification numbers were used to record data at specific locations during the site investigation. The panel numbering system is based on a sequential numbering of each panel, from west to east, using the telephone numbering as a control. For example, panel 535-14 is the 14th panel east of phone 535. Each panel has a unique number in this system. Based on the records, there are a total of 1805 panels. There are 18 panels outside of the tunnel to the west of Bear Valley Portal and there are 18 panels outside of the tunnel to the east of Whittier Portal. There are 1769 panels inside the tunnel.
On October 8, 2012, the panels at the Bear Valley end of the tunnel were observed from the portal eastward to Panel 515-01 and then the south rail only was observed between Panel 515-01 and Safe House #4. On October 9, 2012, the panels and the north rail between 515-01 and Safe House #4 were observed, and then the south rail only was observed between Safe House #4 and Whittier Portal. On October 10, 2012, the remaining panels and the north rail between Safe House #4 and Whittier Portal were observed. Observation work in the tunnel was limited to 20-minute windows between traffic flows.
Observations were limited to what could be visually assessed using flashlights and headlamps to supplement the ambient tunnel lighting. The focus was on two items, 1) the condition of the rail head and 2) the condition of the panels.
Summary of rail observations No visible issues with the rail were observed. There was no evidence of broken rail and no significant wear. One location of a post-construction weld was observed, presumably at a broken rail location, and one location of insulated joint (IJ) replacement was observed. Other than these, there were no observed problems with the rail. We assume that AKRR will continue its routine inspections. Given that this line sees light tonnage (mixed traffic, freight and passenger) it is reasonable to assume that if the existing service patterns continue, the useful life of the rail could be another 30 years.
Based on these observations, the condition of the rail does not appear to be a contributing factor to the reliable performance of the track circuits.
Summary of panel observations The overall condition of the panels outside the tunnel is very different from the overall condition of the panels inside the tunnel. Outside the tunnel, the panels, rubber inserts and joint material are all very weathered. Inside the tunnel, where, conditions are climate controlled, relatively speaking, the panels are overall, in very good condition. There are some sections inside the tunnel where the embedded track system appears to have barely aged at all.
Cracks Observations: 1) there were 210 panels which had a single crack, from side-to-side, at the middle of the panel; 2) there were 24 panels with two or more cracks; 3) and there were 5 panels which were cracked
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Evaluation of Track Circuits Through Whittier Tunnel at other locations, such as the end or corner. No attempt was made to differentiate between cracks based on the width of the crack. Out of 1805 panels, a total of 239, or 13%, were observed to have cracks. There was no discernible pattern of cracked panels. The locations appear to be random: they did not appear to be grouped or clustered. There was no visible evidence of corrosion from the water penetrating the cracks and corroding the steel reinforcement. Cracked panels are listed in Appendix I.
Some panels being cracked is not, by itself, affecting the performance of the track circuits. However the cracked panels combined with the lack of water control probably is affecting the track circuits. Water control is discussed later in this report.
We discussed the issue of
cracked panels with the Star Track® manufacturer’s
representative. In their Figure 8. Panel With Cracks experience, it is not uncommon for panels to crack. Their recommended repair procedure for cracks up to 2- to 3-mm width (the thickness of a credit card) is to clean the crack and inject a Sika® product (SIKADUR 55 SLV). This repair would work for the majority of the cracks.
However there were some locations where panels were severely cracked. We were told that there were several locations like this which were affected during construction: rock being removed from the tunnel ceiling dropped onto the panel and the impact caused the crack. These panels should be evaluated for other repair or replacement options.
Surface Deterioration Observations - there were 368 panels, 20% of the total, which had surface deterioration. In almost all of these, the panel was under or near a visibly active water leak from either the roof or the tunnel wall. Over time, the combined effect of the erosion action between the water, the asphalt and the automobile tires is wearing away the surface of the panels. It appears that the water initially breaks down the bituminous binder in the asphalt and releases small amounts of aggregate. The aggregate in turn forms a paste with the water and increases the erosion of both the asphalt in-fill and the surface of the pre-cast panels. There may also be some additional consolidation of the asphalt occurring.
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Overall, the concrete panel surface conditions vary. At dry locations, it is very good. At wet locations, it is worn. The use of studded tires during winter months is contributing to the wearing. The condition of the asphalt in-fill also varies. As with the panels, the asphalt is in good condition at dry locations and is worn at wet locations.
Figure 9. Panel Repair With Bituminous Fill
The surface deterioration of the asphalt in-fill and the pre-cast panels, by itself, is not affecting the performance of the track circuits. However the long-term impact is the eventual, complete deterioration of the asphalt in-fill. Controlling water and preventing it from falling from the tunnel roof or splashing from the tunnel walls would be a significant improvement.
Spot repair of some of the worst areas of bituminous erosion can be done by removing the existing material and replacing it in-kind. The worn panels cannot be repaired and would have to be completely replaced.
Joints Observations: 59 panels, or 3% of the total, were observed to have lost joint material. The majority of the locations where joint material is missing are at the panels outside of the tunnel. In 2008, all of the panel joints were resealed in a span of three nights. This could explain why the total number of observations is so low. As with the cracks, the missing joint material combined with the lack of water control may affect the track circuits.
Spot replacement of the missing joint material is a straightforward maintenance item.
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Settled panels Observations: there were 46 panels, or 3% of the total, which were observed to have settled. Settled panels were observed in groups. One group is between Safe House #1 and Safe House #2, centered around Telephone #522. Another group is at Safe House #3. There are a couple of isolated panels between Safe House #3 and the Whittier Tunnel, in the area referred to as the “car wash”. Ground-penetrating radar study of the subgrade below the panels may help to understand the existing conditions that are contributing to the settlement.
We were told that some panels are rocking under truck traffic and that train cars can be seen rocking back and forth, particularly near Safe House #3. We were also told by one of the maintenance team that when the tunnel first opened, the driving surface was very uniform. The driving surface now has an irregular profile and snow plows and other equipment have to be driven at lower speeds than they once could, because otherwise they rock and buck severely. The settlement of the panels and loss of cross- Figure 10. Wet Panels level is probably a contributing factor to both of these situations.
We discussed the issue of panel settlement with the Star Track® manufacturer’s representative. Their recommendation is to inject grout, under pressure, through the grout ports in the panels, to lift the panels and bring them back into vertical alignment. The process is called mud-jacking or slab-jacking.
Rubber Rail Seal The rubber rail seal was installed in the panels outside of the tunnel and at the first 50 feet inside the tunnel. It is also installed at the insulated joint in the middle of the tunnel, near Safe House #3. Outside the tunnel, the rail seal is very weathered and is in poor condition. Inside the tunnel, it is in good condition.
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Pandrol® Clips and Other Track Material (OTM) Pandrol® clips and OTM were not assessed. Given the wet conditions, we assume that the clips and OTM have experienced some corrosion. This is not likely to affect the performance of the track because the rails are permanently stabilized by the asphalt in-fill.
Water Issues Whittier Tunnel does not have a liner. There are locations that have pans for water control. However, there are many locations where water rains down on the road/track surface from the roof or splashes in from water cascading down the wall. The rate of water incursion varies: at some locations it is a steady drip, other locations, like the “Car Wash” between Safe House #8 and Whittier Portal are like a waterfall. The observations we made were done in early autumn; it is plausible that water leak rates and locations vary with the season.
As noted above, the continuous presence of water is contributing to the deterioration of the panels and the asphalt in-fill and probably is also affecting the Pandrol® clips, OTM and the rail.
Water is also compromising the insulating nature of the Star Track panel system. As described above, the Star Track system is intended to provide electrical isolation of the running rails from the concrete panel by 1) installing a 3/16-inch thick continuous polyethylene pad between the base of the rail and the concrete, 2) by inserting nylon insulators between the e-clip and the flange of the rail and by 3) installing the rubber Rail Seal to complete the roadway surface. However, also as noted, asphalt in-fill was used in lieu of the Rail Seal throughout the length of the tunnel. Due to cracks in the panels, deterioration of the asphalt in-fill, loss of joint material and the pervasively wet conditions, the electrical isolation has been compromised and has affected the operation of the signal system.
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Track Circuit Overview Track circuits are used to detect the presence of a train on a section of track defined by insulated joints in the rails. There are two track circuits in the Whittier Tunnel, 1OST & 2OST respectively. The 1OST track circuit is roughly 8000 ft. (2438.4m) in length and runs from Bear Valley to Safe House #4. The
2OST circuit is approximately 6400 ft. (1950.7m) long and extends from Safe House #4 to the signal bungalow at Whittier portal. The OST designation for the track circuit generally refers to Over Switch
Figure 11. Safehouse 4 NEMA Enclosure Figure 12. Safehouse 4 Electro-Code
Track. This term refers to track circuits within interlocking locking limits that most often are used to detect the presence of a train on a switch. The OS track circuit will prevent the switch from being thrown while a train is occupying that section of track. Each track circuit within the Whittier Tunnel traverses switches that act as derails outside the tunnel at each end. There are many types of track circuits in use in railroad signal systems. The Alaska Railroad uses electronic coded track circuits in the Whittier Tunnel. Its dual-pulse, bi-directional modulated coding scheme vitally transmits signal aspect information over the rails between locations, thus eliminating the need to run signal cables through the tunnel to convey track occupancy between Bear Valley and Whittier. The Electro-Code track circuit signals are processed through an analog to digital conversion to improve broken rail protection, shunt sensitivity, and noise immunity. DSP (digital signal processing) technology adds digital filtering capability. Track circuit block lengths can be designed up to 23,000 feet under ideal ballast conditions. Track occupancy status received from either of the track circuit module units is interfaced with the signal system to prevent opposing signals from simultaneously clearing. In parallel with that, the track status is relayed to the tunnel control system to allow/prevent automobile traffic based upon tunnel occupancy status. The two track circuits meet at Safe House #4 where a NEMA enclosure houses the cardfile and associated equipment for the two track circuits. There is no wired interface at this location to the signal or tunnel control systems. Each of the track circuits is comprised of mixed vendor equipment with the end unit E-Code system manufactured by Ansaldo STS and the Electro-Code 5 system at Safe House #4 manufactured by General Electric Transportation Systems (GETS). On the tracks where 1OST and 2OST meet at Safe House #4, there is a set of insulated joints. An insulated joint
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Evaluation of Track Circuits Through Whittier Tunnel is defined as “A rail joint in which electrical insulation is provided between adjoining rails”.3 The insulated joints are maintenance intensive sections of track. In block signaling it is necessary to have sections of track electrically insulated from each other, disallowing the rail to be continuously welded seamlessly the length of the track section. The insulated joint is substantially weaker than the rail and is subjected to large stresses which may cause more frequent failures than un-jointed rail. The effect of a failed insulated joint will be indicated by a false occupancy indication. AREMA recommendations call for visual inspection of insulated joints for various signs of potential failure points and deterioration. With the apparent fouling of the insulated joint Figure 13. Sludge Encrusted Insulated Joint At by the rail flange sludge, the Safehouse 4. efficiency of the insulated joint may be questionable. The insulated joint on the south rail was recently replaced. Asphalt was used instead of rubber seals to protect the rail.
Track Circuit 1OST
Whittier to Safe House #4, 1OST Track
To investigate the effects of ballast resistance on the track circuits in Figure 14. Normal Insulated Joint. Whittier Tunnel, the track circuit between Bear Valley and Safe House #4 (2OST) was turned off and opened at both locations. The track circuit that extends from Safe House #4 to Whittier was opened at the Safe House location and placed on DC steady energy at the Whittier location. Voltage readings were taken approximately every 140 feet (20 track panels) and recorded to determine the voltage drop in the open track circuit over the length of the track. Each reading showed a consistent drop in voltage along the track with no significant variance at any specific location. However, as readings were being taken, we were required to clear for auto traffic approximately 2700 feet into the track section. When allowed to return to the track to continue taking measurements, the circuit voltage had risen by approximately 30 mv from where we had left off. To provide assurance that the
3 49 CFR §236.752
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Evaluation of Track Circuits Through Whittier Tunnel anomaly being witnessed was not a faulty reading, five readings were recorded at locations to the rear of where we had left off. Each of these readings corroborated the inexplicable rise in voltage. It was decided to proceed forward toward the middle of the tunnel and deliberate over the variance later.
Inspection of the conditions around the track while walking through the tunnel revealed a wet surface through the first half of the tunnel. A tunnel Inspection Form submitted Figure 15 – Percolated Mud by Alaska DOT supports this observation by highlighting the specific wet panels in this section of the tunnel. This area of the tunnel also shows some of the larger void areas as recorded by the GPR survey report that could collect water/dirt. The pumping action of the concrete slab would facilitate movement of mud and cause it to percolate to the rail.
The voltage drop toward the middle of the tunnel begins to level off showing a slightly less severe loss due to the ballast resistance. Aside from the abnormal rise in voltage witnessed after auto traffic progressed through the tunnel, the steady drop in voltage indicates that no single area of the track circuit is having a causal effect on track circuit operation. It appears as if it is the cumulative effect of the poor circuit conditions throughout the circuit that is having a negative effect on the operation of the circuit.
One potential hypothesis for the increased voltage readings after the auto traffic could be the egress of contaminants away from the rail. Progressing through the tunnel, we were required to clear for traffic approximately every 20 minutes. Track circuit values were not observed to change at any time after the first anomaly at Phone Box 573+10. Speculation may be that the truck and auto traffic slightly rocked or shifted a panel, possibly over one of the void sections, which increased the ballast resistance of the circuit. The precise reason for the voltage shift was not further investigated.
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Track Circuit 2OST
Safe House #4 to Bear Valley, 2OST Track To investigate the effects of ballast resistance on the 2OST track circuit in Whittier Tunnel, the track circuit between Whittier and Safe House #4 (1OST) was turned off and opened at both locations. The track circuit that extends from Safe House #4 to Bear Valley was opened at the Safe House location and placed on DC steady energy at the Bear Valley location. Voltage readings were taken approximately every 140 feet (20 track panels) and recorded to determine the voltage drop in the open track circuit over the length of the track. Similar to 1OST, each reading showed a consistent drop in voltage along the track with no significant variance at any specific location. The calculated ballast resistance for 2OST is 0.94 ohms per 1000 ft of track. This is far below the recommended AREMA minimum value of 2 ohms per 1000 ft
Safe House #4 Insulated Joint Location
Insulated Joints Separating 1OST and
2OST At the Safe House #4 location there are insulated joints (IJ’s) cut into each rail to separate 1OST and
2OST from each other. Figure 16. Booted IJ Figure 17. Encased IJ The joint on the north rail, or the rail closest to the Safe House (Figure 12), is encased in a rubber boot. The rubber boot allows for non-destructive access to the joint and enables maintenance forces from the Alaska Railroad to inspect the condition of the insulated joint and the wires that feed the track circuit. The south rail, or the rail farthest from the Safe House (Figure 13) is fully encased in the bituminous fill. The bituminous fill requires the Alaska Railroad to remove the fill before attempting to inspect the joint, then repacking the rail with fill when the inspection is complete. As previously stated, AREMA recommends access to allow for visual inspection of insulated joints. Generally, polarities at track circuit boundaries are staggered (reversed) to prevent insulated joint failures from falsely energizing the adjacent track circuit with a train (shunt) on the track. Often, the failure of an IJ will cause one or both of the track circuits to show a false occupancy. This is usually dependent upon the strength of the transmit and receive signals in the track circuits on both sides of the
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Evaluation of Track Circuits Through Whittier Tunnel joints. Unfortunately, this condition may only be intermittent and could change each time a train runs through the tunnel.
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Voltage Drop - Safe House 4 To Whittier
(1OST) Whittier 0.46 Signal House Assumed drop 0.45 PB – Phone Box VDC – Volts Direct Current Anomaly 0.44
0.43
0.42 Wet Areas throughout first Relative Leveling half of track circuit. VDC 0.41
0.4
Safe House #4 Wet
0.39
Assumed drop 0.38
0.37
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VDC
Track Wires Signal BEAR Start Panels
VALLEY Door House PB 511
PB 511 +20 PB 512
PB 512 +20 Voltage
Burns PB 513
PB 513 +20 of
Tr
Engineering, PB 514 ck
PB 514 +20 Drop
PB 516 rc PB 516 +20
-
T
PB 516 +40 Inc. Bear
PB 517 r
PB 521 g
W PB 521 +20 Valley PB 522
PB 522 +20 T er
PB 523 To PB 523 +20
e PB 525 Safe
PB 525 +20 Bituminous Defective
PB 533 House fill
PB 533 +20
PB 535
PB 535 +20 VDC PB
4 -
PB 531 Phone -
PB 531 +20 Voltage
PB 534 Box
PB 534 +20 Direct
PB 536
PB 536 +20 Current PB 537 Wet Safe
PB 537 +20
PB 541 House PB 541 +20 Page
PB 542 #4
26 Track Wires
Evaluation of Track Circuits Through Whittier Tunnel
To assess the condition of the insulated joints at Safe House #4, voltage reading were taken across each IJ into the dead section of track to ascertain if the joint was leaking voltage across joint boundaries. With the adjacent track circuit deenergized, no track voltage should have been detected on the adjacent track. Readings at the site revealed that there was leakage in both insulated joints at Safe House #4, but the south rail, the joint encased in the bituminous fill, showed considerably more leakage than the booted rail. This may have affected the operating efficiency of the track circuits in the tunnel, but the recorded measurements are only a snapshot of time and the conditions of the IJ could change over time and operating conditions. The voltage leaked across IJ on south rail may be indicative of potential circuit failure. The joint should be inspected per AREMA and FRA standards.
.084 VDC V
Whittier
V .341 VDC
Figure 18. Diagram Showing Voltage Path Through IJ On South Rail. Feed From Whittier CIH.
.319 VDC V
Bear Valley
V .112 VDC
Figure 19. Diagram Showing Voltage Path Through IJ On South Rail. Feed From Bear Valley CIH.
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Conclusions Based on the inspections and tests made at the Whittier tunnel, the conclusions reached for insuring reliable track circuit operation provides few surprises and validates many of the hypothesis presented by various personnel interviewed for this report. The findings for this report conclude that:
1. There is no single civil/ mechanical cause for the track circuit failures within the tunnel but, the low ballast resistance is ultimately the root cause of the failures.
2. The tunnel track is permanently wet in some areas due to dripping water from the ceiling and percolating water from the ground. The water, combined with road dirt from vehicular traffic in the track area, is acting to lower the overall ballast resistance to the track circuit in the tunnel.
3. Bituminous fill around the rail is breaking down due to vibration and moisture, contributing to the sludge like buildup in the wheel flangeway which is causing current leakage to ground and may be inhibiting shunting efficiency and broken rail protection.
4. Should the combination of dirt, water and sludge reach the head of the rail, it may act as an insulator between the wheels of a train and the track circuit causing a loss of shunt protection to the train.
5. Drying out the tunnel may increase the ballast resistance to allow for reducing the power required for track circuit operation. Ballast resistance and track circuit power are inversely proportional, but weather conditions or track panel infrastructure deterioration may cause unstable track circuit ballast conditions.
6. Unless the rails are completely booted, there is little difference between a rubber rail seal as presently used on the approach sections and the bituminous fill used in the tunnel. The greatest impediment to reliable track circuit functionality is the pervasiveness of wet sludge contaminating the rail trough in the panels.
7. It is dangerous to have the track circuits adjusted for maximum power when a change to the tunnel characteristics may overdrive the track circuits resulting in failure to properly shunt and failure to detect the presence of a train.
8. Ballast resistance deterioration within the tunnel appears to have leveled off over the course of the last few years. This implies that the tunnel track circuits will probably not get much worse in the future.
9. The insulated joint located at Safe House #4 on the south rail is embedded in bituminous fill which reduces its effectiveness in isolating one rail from the other. Each insulated joint should be accessible for visual inspection to the AKRR maintenance crews.
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10. Broken rail protection within the tunnel is not critical to safety because of the embedded track structure.
Recommendations A critical component of this report is to provide recommendations for a permanent solution to tunnel safety as it relates to train detection. To permanently eliminate the problem of track circuit failure in the tunnel due to water, mud, corrosion, etc., there are two mitigation strategies that can be readily implemented with minor capital investment and little impact to operations. A third strategy was investigated that would require a more significant investment in time, effort and money.
Recommendation 1 - Axle Counters The installation of axle counters in lieu of track circuits is the most effective way to insure that track conditions within the tunnel do not affect the operation of the wayside signal system. The term “axle counters” refers to the subsystem which is used for track vacancy detection on steel rail guideway systems such as railways. Axle counters function by detecting the presence and traveling direction of wheels at entrance and exit points of defined blocks of track. When a train enters a block outfitted with axle counters, the wheels (axles) are counted into and out of the block. If the same amount of axles are detected departing the block as were previously detected entering it, the block is considered vacant.
Figure 20. Axle Counter Architecture
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Basic Axle Counter System Components Axle counters primarily consist of two types of components, the double axle counting head, and the axle counting computer (sometimes referred to as an evaluation computer). The axle counting heads are mounted alongside the rail profile and act to detect the presence of wheels. For the Whittier tunnel application, the counting heads would be mounted at the start of the 1OST track circuit at Whittier (outside of the tunnel) with the other set located at Bear Valley. The axle counter circuit protects the track section and provides clear and occupied contact outputs for the external signaling equipment. The double wheel sensor is employed to detect the train wheel flange passing over the wheel sensor and provides output pulses for each axle that passes over it to the two dual on board switching amplifiers. Each wheel sensor consists of 2 individual internal counting points (i.e., double wheel sensor), one double wheel sensor is required for each end of the track section. Both wheel sensor internal systems work independently and send their impulses per wheel flange to Figure 21 – Axle Counter Transducer Mounted On Rail the input of both switching amplifier modules which they are interfaced to. The wheel sensor is typically wired to a junction box at track side and then 18 gauge shielded twisted pair cable is ran from the junction box back to the 19” card cage DIN rail mounted terminals. The design of the wheel sensor also includes a "drop-off-detection". This ensures that if a wheel sensor drops off the rail or is de-installed it will send a specific signal to the amplifier that will activate a break down output which in turns activates the axle counting system to indicate the system is in failure mode. The evaluation computers will reside in the wayside signal bungalows at Whittier and Bear Valley. The evaluation computer will generate the data received from the axle counting heads and generate either a vacant or occupied declaration of the tunnel block. The axle counting heads and the computer are physically connected, typically by copper wire to sense the condition of the fields created within the head about the rail. The Whittier Tunnel solution will use fiber optic cable as a transmission media to transmit and receive data from Whittier to the Bear Valley end of the tunnel. An evaluation of the connection from the signal houses at either end
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Evaluation of Track Circuits Through Whittier Tunnel of the tunnel to the fiber cable running the length of the tunnel will be required prior to completing the final design for the fiber communications. The evaluation computers will interface to the MicroLok interlocking controllers via a dry contact relay interface.
Advantages of Axle Counters
The obvious advantage of using axle counters is their independence from the physical limitations imposed by using the rails as a transmission system. In the case of the Whittier Tunnel, wet or dry, mud or snow, 8,000 or 14,000 feet, the axle counter is impervious to these constraints.
By placing an evaluation computer at either end of the circuit, the axle counter will provide real time inputs to the MicroLok processor over Whittier Tunnels new fiber optic network.
Installation of the axle counter can be Figure 22 – Example of a Rack Mounted Axle performed without disruption to road or rail Counter Evaluation Unit. traffic. No modifications to the roadbed or track panels are required. All testing of the system may be done off line prior to placing the system in service with a short in-service cutover to enter the axle counter input into the processor. Off-line training for maintenance personnel may be facilitated prior to placing the system into full service. One reputable manufacturer estimates that the entire process of converting from track circuits to axle counters may be 4 completed in three days. Experience with axle counters in Europe demonstrates an improvement of up to five times the reliability of track circuits carrying out the same function. This has an immediate improvement in service reliability as track circuit failure is often the most significant cause of train delay. It also has safety benefits as it reduces the use of degraded modes of operation outside of the control of the signaling system due to failure. Axle counters have a history of use in the lower 485 and can be found on Class 1 railroads such as BNSF, Conrail and CSX. They also are in use on Metro North in New York and the Hiawatha Line in Minneapolis. Tiefenbach USA (www.tiefenbach.com), Thales Group (www.thalesgroup.com/Portfolio/Security/D3S_axle_counter) and Frauscher Sensor Technology (www.frauscher.com/en/mainlines_measuring_systems) are examples of three manufacturers currently with safety critical axle counters on the market. No insulated joints are required with axle counters and existing joints have no impact on the axle counter operation. As previously stated, insulated joints are often the weakest link in the rail track
4 Summers Only (ed.) 5 Contact information is available upon request
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Evaluation of Track Circuits Through Whittier Tunnel structure. Axle counters will allow the insulated joint at Safe House #4 to become irrelevant to the signal system and it may be retired if and when the Alaska Railroad feels compelled to remove it.
Disadvantages of Axle Counters The main disadvantage most often heard when discussing axle counters is the lack of broken rail detection that is inherently provided with track circuits. In fact, although track circuits are not specifically required in the new PTC rules (CFR 49 “Part I”), they do require broken rail detection for speeds above 59 mph for passenger trains and 49 mph for freight trains. Although there is a great deal of controversy in the industry as to the percentage of broken rails actually detected by track circuits before they are traversed by a train, axle counters will not detect any break whatsoever. In the case of Whittier Tunnel, this issue becomes almost irrelevant due to the fact that the rail is essentially bordering on direct fixation embedded track. In the case of a break, the rail will most likely fail to dislodge itself from the track structure. As previously stated, there have been two rail breaks in Whittier Tunnel, each of which has failed to be detected by the track circuit. If,r fo any reason there is a failure (possibly a loss of power during a train movement through the tunnel), axle counters can be manually reset (the default start up mode is to create an occupied block). This can be done remotely, but requires a pro-active, manual manipulation. The mitigation strategy for this scenario is the use of storage batteries for back-up power. No “shunt” – track circuits can be easily physically shunted by maintenance personnel (hard wired shunt applied to the rails), axle counters do not provide this function. A manual occupancy can be accomplished with axle counters by hand manipulation of a metal object in front of the sensor. However, there is no visualization of the state (as is the case with a physical shunt), and the system must be reset.
Recommendation 2 – A More Robust Track Circuit A second alternative to the existing Electro-Code system is to update the system to a MicroTrax track circuit system. The Ansaldo MicroTrax system is a simple, easily installed system for a variety of track circuit applications. The MicroTrax ® Coded Track Circuit is a solid state, programmable, microprocessor-based system designed to control wayside circuit applications in non-electrified territory. It is very similar to the E- Code system which is presently being used in the Whittier Tunnel. The track code signal format is AC and is connected to the rails through a Track Interface Panel that consists of a transformer and a low impedance inductor. A MicroTrax system consists of a Coded Track Circuit Unit cardfile assembly with plug-in modules and one-track interface panel per operating track. In the Whittier Tunnel track circuits, the existing cardfile assembly may be utilized at the Whittier and Bear Valley bungalow locations. At Safe House #4, a new cardfile will need to be installed to replace the existing Electro-Code 5 chassis along with a new track interface panel (TIP). As an option, to eliminate the insulated joint at
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Safe House #4, the MicroTrax track circuit may be able to extend the length of the tunnel for the full 14,000 plus feet. MicroTrax has a history of extending over 35,000 feet in some cases. Primarily, the MICROTRAX system is used to manage track circuits by providing end-to-end rail integrity, including detection of a train shunt, faulty insulated joint, or broken rail.
Advantages Advantages of the MicroTrax system include:
• Track circuits are well known and are the de facto standard for train detection for over 125 years.
• Track circuits in excess of four miles with minimum three ohm ballast. Ballast resistance in Whittier calculated to approximately one ohm. Even with low ballast resistance, the 2.5 mile tunnel circuit may be possible. If so, the insulated joint in the tunnel may be eliminated.
• Simple configurable software using the standard MicroLok tools that AKRR is already familiar with. • Two user-defined fast codes with a six second acceptance time (typically used for tumbledown). The tumbledown mode may be required if it is necessary to retain the insulated joint at Safe House #4.
• Quick Shunt mode (reduces shunt time from 6–12 seconds to 100 milliseconds).
• Adjustments for track circuit to compensate for length and ballast conditions made from the Central Processing Unit (CPU) module. The CPU also provides the ability to review track circuit functionality through a scrolling menu.
• The price of purchasing and installing a new MicroTrax track system will be the most financially appealing.
• The MicroTrax Coded Track Circuit Unit can manage track circuits and be interfaced the MicroLok® controlling unit. In utilizing the existing cardfile and MicroLok interlocking processor, minor changes to the MicroLok program will be required to integrate the track circuit to the interlocking.
Disadvantages • More of the same? While the MicroTrax has a proven track record in difficult low ballast resistance locales, the problem of deteriorating ballast conditions remains. The requirements that track circuit monitoring for changing ballast conditions must be maintained. This may be akin to putting a band- aid on the problem.
• FRA testing of track circuit functionality is required. Track circuits are, by design, reliant on a very specific shunting characteristic of train axles (often 0.06 or 0.25 Ohms). If a train axle actually differs from this resistance (perhaps due to environmental influences such as those mentioned in this report), track circuits can “overlook” trains and incorrectly determine track vacancy.
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• The MicroTrax track circuit has a slow recovery time based on the bi-polar code scheme which consists of a pattern of positive and negative pulses. Each message is two seconds long and contains an equal number of short positive and negative pulses, and an equal number of long positive and negative pulses. Recovery time for a single track circuit may be a long as 18 seconds.
• Cut-over of new track circuit will require a short interruption to the normal operational schedule.
• Properly maintained insulated joints remain vital to the operation of the circuit.
Recommendation 3 –Polymeric Encasement or Rubber Boot Around the Rail An insulating rail boot or some other form of polymeric trough component encasing a rail embedded in the Startrack panels would serve to insulate each rail from each other. The resilient material used in the panel would help distribute load, mitigate vibration and would provide the necessary electrical insulation to help insure track ballast resistance remains high and track circuit current remains concentrated in the rails Where a rail boot is used, the rail and the rail boot are secured in place by retaining clips. ·Then a bituminous asphalt or concrete filler is poured around the boot to serve as a smooth running surface for vehicular traffic. Where polymeric encasement is used, it is recommended that an isolating base matting be used under the rail. Elastomeric Products We identified two elastomeric products that potentially could be used to encapsulate the rail: 1. a CDM-Novitec product called CDM-Qtrack 2. an edilon)(sedra product called EDILON Corkelast. Both of these systems are common in Europe but there are only a few installations in the U.S. The CDM-Qtrack system is a combination of rubber blocks and elastomeric in-fill. In this system rubber blocks are adhered to the rail, leaving a wide gap between the rubber and the edge of the slot in the concrete panel. The gap is filled with a pourable elastomeric compound that hardens and completes the support of the rail and the electrical isolation. To build the system, the existing rails would have to be removed and the slot cleaned and prepped. The shoulders for the Pandrol e-clips are removed. An isolation pad is placed on the bottom of the concrete slot. The rail is replaced and rubber blocks (or jackets) are adhered to each side of the rail. The elastomeric in-fill (CDM-ERF) is placed in the gaps between the rubber and the concrete in two separate pours with cure time in between. The vendor provided a material price of $75 per track foot for the rubber and elastomeric in-fill. We estimate the total cost for this system would be $2.4m, which includes labor for removing and re-installing the rail. The EDILON Corkelast system is based on a pourable polyurethane and cork mixture that hardens to support the rail and provide electrical isolation. Due to high material costs, the vendor recommended that for Whittier Tunnel, additional concrete be poured along the sides of the existing slots in the pre- cast panels to reduce the volume of Corkelast material required for the installation. To build the system, the existing rails would have to be removed and the slot cleaned and prepped. The shoulders
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Evaluation of Track Circuits Through Whittier Tunnel for the Pandrol e-clips are removed. Concrete would then be poured in place along the edge of each slot. The rail would be placed back into the slot on top of a strip of elastomer, to insulate the bottom of the rail from the pre-cast panel. Construction would be completed by pouring the Corkelast. The vendor provided an installed price of $700 per track meter for new construction. We estimate the total cost for this system would be $4.1m, which includes labor for removing the existing rail, since this is a retrofit, not new construction. Rail Boots Unlike the two pourable elastomeric products, rail boots are relatively common in the U.S. A boot system is comprised of a rubber jacket that wraps completely around the rail section and, when used in the Star Track pre-cast panel system, it includes rubber rail seals to fill the gap between the rail head and the concrete panel. We contacted two vendors: PPI and Poly-Corp. PPI’s products are typically co- specified with the Star Track system. Poly-Corp is a competitor. PPI provided a material price of $113 per track foot for boots and rails seals. We estimate the total cost for this system would be $3.0 m, which includes labor for removing and re-installing the rail. PPI suggested an alternate, which they described as a “bondable” boot. The bondable boot is made from a special material that is adhered to the web and sides of the head of the rail and therefore does not require the installation of rail seals when used with the Star Track panels. In lieu of the rail seals, the slot in the panels can be in-filled with Portland cement concrete or asphalt after the bondable boot is installed. PPI provided an estimated material price of $60 per track foot for the bondable boot. We estimate the total cost for this system would be $2.3m, which includes asphalt in-fill and labor for removing and re-installing the rail. Poly -Corp provided a material price of $105 per track foot for boots and rail seals. We estimate the total cost for this system would be $2.9m, which includes labor for removing and re-installing the rail. Advantages
• The high level of electrical resistivity provided by the thermoplastic elastomer prohibits the signal current from finding its way to ground and to the other rail.
• The embedded portion of the rail is completely encased with vibration damping, elastomeric polymer. The close proximity of the rail boot allows for maximum surface contact with the rail. The elasticity of the polymer helps to dampen vibration imparted to the rail by the passing street cars and train. This limits the detrimental effects on the rigid concrete roadbed, created by track vibration.
• The elastomeric compression of the boot helps limit and control the amount of rail movement. Controlling the rail, inside the concrete encasement, prohibits the transfer of destructive forces to the concrete rail panels. This isolation should reduce the period between maintenance intervals.
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• Star Track customized boot kits are available to fit specifically in the Star Track Panels used in the Whittier Tunnel. The kits would provide the correct fit in the panel to insure that electrical isolation and vibration dampening are maintained. Star Track can also supply seam filler to reduce the infiltration of detritus from the substrata. Disadvantages • The high cost of material and installation. Material and installation costs will be significantly higher than the other alternatives mentioned above. To install the insulating boot or the elastomeric polymer fill, the existing bituminous fill will need to be completely removed. The rail must be pulled out of the panel’s rail channel and then be encased in the boot. Should an elastomeric polymer fill be used in lieu of the boot, the rail will still need to be raised to allow a rubberized base matting to be placed underneath the rail. New insulated rail clips will need to be installed in both scenarios.
• The scheduling of this type of work will interfere with the operation of the tunnel for auto and rail traffic. The track contractor will have mandatory work hours during a night time shutdown and will be required to have the road and the track restored for daytime operation.
• The lifecycle for this type of restoration hovers around 15 years when the process will need to be repeated.
Immediate Remediation Initiatives Based on our observations we make the following recommendations: 1. At the insulated joint repair in the middle of the tunnel, the rail slot was backfilled with asphalt. Remove the asphalt and install one section of rubber Rail Seal, which will allow visual inspection of the insulated joint. 2. Control water that is falling from the roof and walls of the tunnel. Prevent it from entering the roadway by installing pans and pipe. Continue to maintain the tunnel drainage system, including periodic inspection and repair of the sump pumps. 3. Slab-jack panels that have settled. 4. Spot remove and replace the deteriorated asphalt in-fill. 5. Continue to monitor the condition of cracked panels.
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APPENDIX I
LIST OF CRACKED PANELS
Phone Location ID # BVP-12 BVP-13 BVP-18 BVP 511 511-01 511-04 512 512-09 512-11 512-13 512-15 512-33 513 513-01 513-03 514 514-11 514-21 514-28 515 515-01 515-06 515-09 516 516-05 516-13 516-15 516-17 516-27 516-29 516-35 516-43 517 517-01 521 521-06 521-10 521-12 521-21 521-30 522 522-02 522-04 522-35 522-37 523 523-01 523-04 524 524-02 524-06 524-26 524-27 524-38 525 525-08 525-10 525-17 525-20 525-24 525-26 525-27 525-28 525-32 525-33 525-38 531 531-02 531-05 531-13 531-24 531-31 531-34 531-36 532 532-02 532-04 532-06 532-08 532-09 532-10 533 533-01 533-03 533-06 533-20 533-23 533-24 533-27 533-30 533-32 534 534-01 534-02 534-05 534-08 534-14 534-28 534-30 534-37 534-40 535 535-03 535-05 535-14 535-18 535-28 535-33 535-38 536 536-04 536-07 536-10 536-12 536-15 536-16 536-18 536-24 536-29 536-33 536-38 537 537-02 537-06 537-09 537-15 537-17 537-18 537-23 537-29 537-31 541 541-01 541-08 541-11 541-14 541-15 541-18 541-33 541-35 541-38 542 542-06 542-12 542-17 542-24 542-26 542-36 543 543-05 544 544-05 544-06 544-08 544-17 544-21 544-24 544-26 544-29 544-36 545 545-05 545-08 545-16 545-17 545-18 545-20 545-28 545-30 545-36 545-41 546 546-03 546-05 546-16 546-19 546-34 551 551-04 551-13 551-15 552 552-03 552-26 552-36 552-38 552-40 553 553-05 554 554-03 554-05 554-14 554-20 554-24 554-31 554-32 555 555-02 556 556-06 556-21 556-32
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562 563 563-03 563-05 563-08 563-15 563-26 564 564-01 564-10 565 565-11 565-13 565-19 565-21 565-29 565-32 565-34 565-36 565-37 565-39 566 566-07 566-10 566-13 566-14 566-29 567 567-02 567-18 567-27 571 571-14 571-17 572 572-06 572-10 572-33 572-38 573 573-04 574 574-01 574-22 574-30 574-31 574-36 576 576-31 581 581-04 581-08 581-12 581-18 581-20 581-21 582 582-19 582-26 583 583-02 583-08 584 584-07 584-11 584-18 584-21 584-25 584-39 585 585-27 586 586-17 586-18 586-20 586-26 Oct. 587 587-14 587-24 587-32 587-34 587-37 2012
BVP – Bear Valley Portal
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APPENDIX II
LIST OF PANELS WITH SURFACE DETERIORATION
BV-01 533-35 551-07 562-10 576-18 586-14 587-24 WP-14 BV-02 533-36 551-08 562-11 576-33 586-15 587-25 WP-15 BV-03 533-37 551-09 562-12 576-34 586-16 587-26 WP-16 BV-04 534-17 551-10 562-15 581-12 586-17 587-27 WP-17 BV-05 534-18 551-11 562-16 581-13 586-18 587-28 WP-18 BV-06 534-19 551-12 563-06 581-14 586-19 587-29 WP-EP BV-07 535-05 551-13 563-07 581-15 586-20 587-30 BV-08 535-07 551-14 563-08 581-16 586-21 587-31 BV-09 535-08 551-15 563-09 581-36 586-22 587-32 BV-10 535-09 551-16 563-10 581-37 586-23 587-33 BV-11 535-10 551-17 563-11 582-01 586-24 587-34 BV-12 535-21 551-18 563-12 583-09 586-25 587-35 BV-13 535-22 551-19 563-13 583-10 586-26 587-36 BV-14 535-23 551-20 563-14 585-10 586-27 587-37 BV-15 535-24 551-21 563-15 585-11 586-28 587-38 BV-16 535-25 551-22 563-16 585-13 586-29 587-39 BV-17 535-26 551-23 563-17 585-22 586-30 588-01 BV-18 535-27 551-24 563-18 585-23 586-31 588-02 524-15 535-28 551-35 563-19 585-24 586-32 588-03 524-22 535-29 551-36 563-20 585-25 586-33 588-04 524-23 535-30 552-02 563-21 585-26 586-34 588-05 524-24 536-06 552-03 563-22 585-27 586-35 588-06 524-25 536-07 552-13 563-23 585-28 586-36 588-07 524-26 542-09 552-14 563-24 585-29 586-37 588-08 524-27 544-28 552-17 563-25 585-30 586-38 588-09 524-28 545-12 552-18 565-33 585-31 587-01 588-10 524-29 545-13 552-23 566-11 585-32 587-02 588-11 524-30 545-14 552-24 567-04 585-33 587-03 588-12 525-05 545-15 552-25 571-15 585-34 587-04 588-13 525-06 545-16 552-26 571-16 585-35 587-05 588-14 525-40 545-17 552-27 574-33 585-36 587-06 588-15 531-20 545-18 554-10 574-34 585-37 587-07 588-16 531-21 545-19 554-11 574-39 585-38 587-08 588-17
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532-05 545-20 554-12 574-40 585-39 587-09 588-18 533-03 545-37 554-33 575-01 585-40 587-10 588-19 533-04 545-38 555-02 575-02 586-01 587-11 WP-01 533-05 545-39 555-32 575-03 586-02 587-12 WP-02 533-06 546-07 555-33 575-04 586-03 587-13 WP-03 533-07 546-26 556-02 575-05 586-04 587-14 WP-04 533-08 546-27 556-03 575-06 586-05 587-15 WP-05 533-09 546-28 556-33 575-07 586-06 587-16 WP-06 533-10 546-29 556-34 575-08 586-07 587-17 WP-07 533-11 546-30 562-02 575-09 586-08 587-18 WP-08 533-12 546-31 562-03 575-10 586-09 587-19 WP-09 533-13 546-32 562-04 575-11 586-10 587-20 WP-10 533-14 546-33 562-05 575-12 586-11 587-21 WP-11 533-33 551-05 562-08 575-13 586-12 587-22 WP-12 533-34 551-06 562-09 576-17 586-13 587-23 WP-13 OCT 2012
Sorted By Phone Location ID Number BV – Bear Valley WP – Whittier Portal
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APPENDIX III
LOCATIONS OF PANELS WITH MISSING SEALANT
BV-01 BV-02 BV-03 BV-04 BV-05 BV-06 BV-07 BV- BV-08 BV-09 BV-10 BV-11 BV-12 BV-13 14 BV-15 BV-16 BV-17 BV-18 BVP-01 BVP-02 BVP-03 BVP-04 BVP-05 BVP-06
524-14 524-18 524-32
572-23 572-24
585-22 585-27 586-18 586-32 586-37 587-05 587-17 WP-01 WP-02 WP-03 WP-04 WP-05 WP-06 WP-07 WP- WP-08 WP-09 WP-10 WP-11 WP-12 WP-13 14 WP-15 WP-16 WP-17 WP-18
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ROUGH ORDER OF MAGNITUDE COST BREAKDOWN
Axle Counter Installation
AXLE COUNTERS
Design and Test Axle Counter System at Whittier Tunnel Alaska Railroad to install using force account labor, support and training provided by designer and axle counter vendor.
ITEMIZED ESTIMATE: TIME AND MATERIALS UNITS HOURS AMOUNT Preparation for communications, evaluation computers & transducers 160 $12,800.00 Test and Commissioning (Force Account) 68 $5,440.00 Track work (IJ Removal) 64 $4,160.00 AKRR Equipment LS $5,000.00 Design and Check 40 $8,000.00 CAD 32 $3,200.00 Vendor Installation Support (Flat Rate $1000 p/day) 5 $5,000.00 Vendor Supplied Material LS $75,000.00 Railroad Supplied Material LS $5,000.00 Consultant Support 40 $8,000.00 T&L $6,500.00
Contingency @ 10% $13,810.00
TOTAL ESTIMATED JOB COST 404 $151,910.00
This is an estimate only, not a contract. This estimate is for completing the job described above, based on our evaluation. It does not include unforeseen price increases or additional labor and materials which may be required should problems arise.
PREPARED BY DATE
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Replace E-Code with MicroTrax Track Circuit
MICROTRAX TRACK CIRCUIT REPLACEMENT
Design and Test MicroTrax Track Circuit System at Whittier Tunnel Alaska Railroad to install using force account labor. Programming, support and training provided by designer.
ITEMIZED ESTIMATE: TIME AND MATERIALS UNITS HOURS AMOUNT Site preparation for new track circuits (Force Account) 48 $3,840.00 Hardware design and check 24 $4,800.00 CAD 16 $1,600.00 Programming design and check 16 $3,200.00 Clean and re-boot IJ's @ SH4 64 $4,160.00 AKRR Equipment (Vehicles) LS $2,500.00 Vendor Supplied Material LS $30,500.00 Railroad Supplied Material $1,000.00 Consultant Support & Training 40 $5,600.00 T&L $2,500.00
Contingency @ 10% $5,970.00
TOTAL ESTIMATED JOB COST 208 $65,670.00
This is an estimate only, not a contract. This estimate is for completing the job described above, based on our evaluation. It does not include unforeseen price increases or additional labor and materials which may be required should problems arise.
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Rail Encasement
RAIL ENCASEMENT
CDM-Novitec Product: CDM-Qtrack Alaska Railroad to install using force account labor, support provided by designer and boot vendor.
ITEMIZED ESTIMATE: TIME AND MATERIALS UNITS HOURS AMOUNT
Track work Days 16000 $1,040,000.00 AKRR Equipment LS $250,000.00 Vendor Supplied Material LS $1,100,000.00 Railroad Supplied Material LS $110,000.00 Consultant Support Hr 160 $16,000.00 T&L $10,000.00
Contingency @ 10% $252,600.00
TOTAL ESTIMATED JOB COST 16160 $2,778,600.00
This is an estimate only, not a contract. This estimate is for completing the job described above, based on our evaluation. It does not include unforeseen price increases or additional labor and materials which may be required should problems arise.
RAIL ENCASEMENT
Edilion)(Sedra product: EDILION Corklast Alaska Railroad to install using force account labor, support provided by designer and boot vendor.
ITEMIZED ESTIMATE: TIME AND MATERIALS UNITS HOURS AMOUNT
Track work Days 41000 $2,665,000.00 AKRR Equipment LS $350,000.00 Vendor Supplied Material LS $1,004,000.00 Railroad Supplied Material LS $100,400.00 Consultant Support Hr 160 $16,000.00 T&L $10,000.00
Contingency @ 10% $414,540.00
TOTAL ESTIMATED JOB COST 41160 $4,559,940.00
This is an estimate only, not a contract. This estimate is for completing the job described above, based on our evaluation es not include unforeseen price increases or additional labor and materials which may be required should problems aris
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RAIL ENCASEMENT
PPI Boot Alaska Railroad to install using force account labor, support provided by designer and boot vendor.
ITEMIZED ESTIMATE: TIME AND MATERIALS UNITS HOURS AMOUNT
Track work Hours 17000 $1,105,000.00 AKRR Equipment LS $300,000.00 Vendor Supplied Material LS $1,600,000.00 Railroad Supplied Material LS $160,000.00 Consultant Support Hr 160 $16,000.00 T&L $10,000.00
Contingency @ 10% $319,100.00
TOTAL ESTIMATED JOB COST 17160 $3,510,100.00
This is an estimate only, not a contract. This estimate is for completing the job described above, based on our evaluation. It does not include unforeseen price increases or additional labor and materials which may be required should problems arise.
RAIL ENCASEMENT
PPI Bondable Boot Alaska Railroad to install using force account labor, support provided by designer and boot vendor.
ITEMIZED ESTIMATE: TIME AND MATERIALS UNITS HOURS AMOUNT
Track work Hours 15575 $1,012,375.00 AKRR Equipment LS $250,000.00 Vendor Supplied Material LS $1,030,000.00 Railroad Supplied Material LS $103,000.00 Consultant Support Hr 160 $16,000.00 T&L $10,000.00
Contingency @ 10% $242,137.50
TOTAL ESTIMATED JOB COST 15735 $2,663,512.50
This is an estimate only, not a contract. This estimate is for completing the job described above, based on our evaluation. It does not include unforeseen price increases or additional labor and materials which may be required should problems arise.
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RAIL ENCASEMENT
Poly Corp Boot Alaska Railroad to install using force account labor, support provided by designer and boot vendor.
ITEMIZED ESTIMATE: TIME AND MATERIALS UNITS HOURS AMOUNT
Track work Hours 16000 $1,040,000.00 AKRR Equipment LS $300,000.00 Vendor Supplied Material LS $1,530,000.00 Railroad Supplied Material LS $153,000.00 Consultant Support Hr 160 $16,000.00 T&L $10,000.00
Contingency @ 10% $304,900.00
TOTAL ESTIMATED JOB COST 16160 $3,353,900.00
This is an estimate only, not a contract. This estimate is for completing the job described above, based on our evaluation. It does not include unforeseen price increases or additional labor and materials which may be required should problems arise.
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