Cb(4)890/16-17(03)
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CB(4)890/16-17(03) Legislative Council Panel on Transport Subcommittee on Matters Relating to Railways Overhead Line Incident on MTR Kwun Tong Line on 10 April 2017 A fault occurred on the overhead line of the MTR Kwun Tong Line (“KTL”) on 10 April 2017, resulting in train service suspension between Kowloon Tong and Kwun Tong stations for around 2 hours and 20 minutes. Service was maintained on other sections of KTL but at reduced frequencies. This paper briefs the Subcommittee on the sequence of events, contingency arrangement, preliminary investigation findings and follow up actions regarding the incident. Sequence of events 2. At around 6:02 p.m. on 10 April 2017, the overhead line between Kwun Tong and Kowloon Tong stations on KTL (Whampoa-bound) tripped, affecting power supply to that section. The protection system was automatically triggered 1 . As a result, train service between Kowloon Tong and Kwun Tong stations on KTL was immediately suspended. When recovering an incident, it has to be carried out in a safe and orderly manner, with safety of passengers and maintenance staff coming first. According to established procedures, the MTR Operations Control Centre (OCC) immediately carried out inspection and recovery with three major steps – (1) firstly, OCC communicated with train captains of the seven trains which were stalled between Kowloon Tong and Kwun Tong stations to establish whether the tripping was caused by fault of any individual train. The preliminary assessment was that the tripping was not caused by a train fault; 1 When an irregularity is detected in the railway system, the protection system will automatically stop the train service, which can only be re-activated after conducting inspection and repair by maintenance staff. The purpose is to avoid the occurrence of more serious incidents and ensure passenger safety, but service disruption or suspension is inevitable in the circumstances. In terms of the power supply system, the protection system will cut off the power supply when it is in unstable condition, such as circuit overload or short circuit. Accordingly, train service will be suspended. 1 (2) there are three power supply zones along the section between Kowloon Tong and Kwun Tong stations (see Annex 1). OCC attempted to re-energise the overhead line power supply for the three zones one by one and was successful in re-energising two of them, namely the zone between Kowloon Bay and Kwun Tong stations and the zone between Diamond Hill and Kowloon Tong stations. Power supply for the remaining zone (between Kowloon Bay and Diamond Hill stations) could not be resumed. Therefore, OCC narrowed down the cause of the incident to the overhead line of that particular section; and (3) maintenance staff was arranged to enter the track between Kowloon Bay and Diamond Hill stations for inspection. 3. In parallel, OCC deployed trains to maintain service at sections where power supply was not affected. During the incident, train service between Kowloon Tong and Whampoa stations was maintained at 10-minute intervals, while service between Tiu Keng Leng and Kwun Tong stations was maintained at 12-minute intervals. 4. After resuming the power supply of two zones, namely between Kowloon Bay and Kwun Tong stations and between Diamond Hill and Kowloon Tong stations, OCC arranged 4 of the 7 trains which were stalled in the affected area to proceed to platforms at Lok Fu, Wong Tai Sin, Kowloon Bay and Kwun Tong stations for passengers to detrain at platforms. Passengers on another train boarded and alighted normally again at Kowloon Tong Station after resumption of power supply at the station. At one juncture, OCC succeeded to temporarily resume power supply at a short section near the platform at Kowloon Bay Station after multiple attempts, so that one train could enter the platform for detrainment. However, this process took a relatively longer period of time, delaying the subsequent inspection to be carried out by maintenance staff on track. This led to longer handling time. 5. Since the power supply for the zone between Diamond Hill and Kowloon Bay stations has yet to be resumed, a train (hereinafter referred to “Train A”) was stalled with two cars into the tunnel and the remaining 6 cars in the platform area of the Choi Hung Station, while the following train (hereinafter referred to “Train B”) was stalled at a location around 30 meters from the Choi Hung Station platform. OCC made a number of attempts to resume power supply for the two trains to proceed to the platform for detrainment, but to no avail. During the process, backup power supply for on-train equipment, including emergency lighting and 2 ventilation systems, was operational2. In around 40 minutes after the incident occurred (i.e. at around 6:42 p.m.), since the power supply for the zone between Diamond Hill and Kowloon Bay stations could not be resumed, OCC decided to detrain the passengers of the two trains in accordance with the safety procedures3 to avoid further delaying the ensuing emergency handling work. MTRCL staff manually opened the platform screen doors at Choi Hung Station and train doors of Train A that were stalled in the platform to detrain passengers. Meanwhile, after confirming as quickly as possible that the overhead line of this section was isolated and no train was on track to ensure track access safety, OCC instructed the captain of Train B to arrange passengers to evacuate onto the track and walk to the platform of Choi Hung Station with the assistance of MTRCL staff. All passengers reached the platform at around 7:30 p.m.. Ambulance had already arrived at Choi Hung Station at the time to convey passengers feeling unwell to the hospital. 6. Meanwhile, maintenance staff confirmed that it would be necessary to conduct detailed inspection of the overhead line along the section between Diamond Hill and Kowloon Bay stations. After ensuring that safety protection measures were in place, four teams of engineering staff comprising three dedicated teams of overhead line maintenance staff and a team of Rapid Respond Unit members with a total of 10 persons were deployed to the track for inspection of the overhead line. Around 30 minutes after entering the track, the maintenance personnel found that two support components on overhead line at the tunnel of a reception track towards Kowloon Bay Depot were loosened, resulting in a slight displacement of a Current Return Wire which caused the tripping. 7. Maintenance staff immediately isolated the faulty overhead line and carried out inspection of the section where train service was suspended in accordance with safety procedures. After confirming that all passengers and other personnel were cleared from the track according to safety check procedures, power supply was resumed for mainline operation and test-run of trains on that section was arranged. Service was resumed upon confirmation of safe and smooth operation. Train service on KTL gradually resumed to normal starting from 8:23 p.m.. 2 The lighting and ventilation systems of Train B were shut down for 3 minutes because the train captain inadvertently pressed the wrong button. 3 MTRCL arranges detrainment at stations as far as practicable because they are more spacious and more staff members are present to assist passengers. Therefore, MTRCL made every endeavor to resume the power supply for trains to approach the stations. Backup power supply was in place to support emergency lighting and ventilation on trains to operate for at least an hour. 3 8. The faulty components were immediately replaced by maintenance personnel after close of traffic on that day. Detailed checking was also carried out on the overhead line and track at the concerned section, as well as the pantographs of trains that passed the concerned sections, to ensure safety. Contingency arrangement during the incident 9. MTRCL has established contingency plans for various kinds of incidents for execution by the staff in different divisions and stations when incident occurs. The contingency arrangement in the event of railway service disruptions is at Annex 2. On 10 April, MTRCL took the following actions according to this plan to minimise the impact on passengers – (a) Notification and information dissemination 10. At 6:05 p.m. on 10 April (i.e. within 3 minutes after the incident took place), MTRCL notified the Transport Department (“TD”) once the incident was expected to last for 8 minutes or more. MTRCL also notified passenger of the service disruption on KTL via the MTR Mobile App “Traffic News” at 6:10 p.m.. Once MTRCL ascertained that the railway section could not be re-energised within a short period of time and that train service would be disrupted for 20 minutes or more, a “Red Alert” message on major service disruptions was issued at 6:23 p.m. to inform TD and the media of the incident, so that TD could coordinate other public transport operators to strengthen their services. MTRCL also notified passengers of the service disruption and provide information on alternate public transport services as well as free MTR shuttle bus services via broadcasting in stations and on trains; signage inside stations and on the roads, as well as the Service Information Panel near station entry gates. 11. MTRCL further updated the public on the latest train service information via “Traffic News” and the media. MTRCL also made announcement via these channels when the KTL service started to gradually resume at 8:23 p.m.. 4 (b) Manpower deployment 12. During the incident, MTRCL deployed around 300 staff members (including operating and station staff, members of the Customer Service Support Unit and Customer Service Rapid Respond Unit) to assist passengers at various affected stations and major interchange stations of KTL, such as Prince Edward and Mong Kok stations.