Joo Koon rail accident

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Joo Koon rail accident
Joo Koon MRT Station, where the accident occurred at the platform towards Tuas Link.
Joo Koon MRT Station, where the accident occurred at the platform towards Tuas Link.
Date 15 November 2017
Time approximately 8.30 a.m. (SST)
Location Joo Koon MRT Station
Country Singapore
Rail line East West MRT Line
Operator SMRT Trains
Type of incident Software failure in CBTC signalling system resulting in collision between two trains[1]
Cause Software-related issue
Statistics
Trains 2 Kawasaki-Sifang C151A trains
Passengers 517[2]
Deaths 0
Injuries 38 (including 2 crew)[3]

The Joo Koon rail accident, or sometimes referred to as the Joo Koon train collision, was an accident which happened on 15 November 2017, when a C151A train travelling at 16 kilometres per hour (9.9 mph) rear-ended a stationary C151A train at Joo Koon station on the East West MRT Line, resulting in 38 injuries.[2][3] The stationary train was in the process of being detrained due to a train fault. Both trains were operating under the recently installed Thales SelTrac CBTC signalling system at time of incident, and the Minister of Transport Khaw Boon Wan expressed that he was "disturbed" by an initial finding that "critical safety software" was inadvertently removed from the stationary train, possibly due to a malfunctioning signalling circuit, which led to the accident.[4] This incident is the second train collision in Singapore MRT's history, after the Clementi rail accident.

Background

The East West MRT Line, at the time of the incident (and up to the present day), was in the transition process between the older Westinghouse ATC fixed block signalling and the newer Thales SelTrac CBTC moving block signalling.[4] Both systems are in use on the same line, but only the newer CBTC signalling equipment was available for the Tuas West Extension between Joo Koon and Tuas Link.[4][5] As a result, trains are required to switch from the Westinghouse signalling to the Thales signalling at Pioneer prior to heading towards Tuas Link, and vice versa in the other direction.[5]

There were previous high-profile train disruptions in June 2017 during the testing phase on the North South MRT Line, when it was transitioning to the Thales SelTrac CBTC.[5] Those incidents were found to be a result of human error when new software was being installed.[5] Before this accident, SMRT had originally scheduled full-line testing of Thales CBTC to begin on the East West Line in December 2017.[5]

Incident

The first train, a Kawasaki-Sifang C151A heading towards Tuas West, had to be removed from service due to a train fault at 8.18am caused by another separate signalling fault.[1][6] The second train headed in the same direction, another C151A, stopped behind the first train while the automatic platform gate was manually opened to allow the detrainment of the first train to take place.[1][6] The second train had 517 passengers on board.[2] As the doors of the first faulty train were closed, the second train suddenly accelerated to a speed of 16 km/h and rear-ended the first train.[2] Witnesses outside the train reported hearing a loud bang.[7] This resulted in 38 injuries, including two SMRT Trains staff members.[2] Many of the injuries resulted from passengers losing balance and impacting the floor or fixtures, and ranged from vomiting to a broken tooth.[2][7] The injured passengers and staff were treated at National University Hospital and Ng Teng Fong General Hospital.[3]

Response and investigation

Reactions

The accident increased public anger and pressure on both SMRT Corporation and Land Transport Authority (LTA),[8] in light of a major tunnel flooding incident weeks prior, which resulted in a discovery that SMRT maintenance workers had failed to perform the necessary maintenance work on its pumps and had falsified records.[9] Both organizations described the accident as one train "coming into contact" with another train in their initial media releases, and this was criticized by commentators and the public as an attempt to downplay the incident.[10][11] A later statement by the LTA changed it to a collision.[10]

Opposition parties have responded to the incident as well. Singapore Democratic Party called for transport minister Khaw Boon Wan to resign, while the Workers Party asked for the authorities to launch an investigation.[12] Prime Minister of Singapore Lee Hsien Loong admitted that both the tunnel flooding and the Joo Koon accident has "hurt public confidence a lot".[9] Despite that, PM Lee has insisted that Singapore's public transport remains "first class".[9]

Transport minister Khaw initially apologized to the commuters involved.[13] Later, Khaw expressed that he was "disturbed" by an initial finding that "critical safety software" was inadvertently removed from the stationary train, possibly due to a malfunctioning signalling circuit, which led to the accident.[4]

Investigation

A preliminary investigation held jointly between SMRT Trains, Land Transport Authority, and Thales found that the first train had had a safety protection feature removed when it went over a faulty signalling circuit.[6] That safety protection feature was designed to fix a known bug which wrongly designated the six-car train as a three-car train under certain degraded modes, such as when the two onboard computers in the train's Thales CBTC system are unable to communicate with each other.[6]

While the first train was being detrained and the automatic platform doors were opened, a separate protection module was activated to block off the entire length of the platform at Joo Koon station.[14][15] The module notified the second train's signalling computer that the Joo Koon station's westbound platform was occupied and to stay clear of the platform.[6][14] The second train stopped at the correct distance behind the first train while the automatic platform doors were open. However, once the doors were closed, the platform length protection module was removed. When the signalling on the second train detected the first train as only three cars instead of six, it started moving to close the perceived gap between both trains for the distance of three cars, thus allowing the acceleration of the second train and the rear-end collision with the first train.[6] SMRT later explained that when the first train was detraining at the platform, a signal was given off to show that the platform was occupied. However, when the platform screen doors closed, the protection was then removed, allowing the second train to hit the first.[16]

Aftermath

Temporary suspension of service

Following the incident, SMRT announced that services on the Tuas West Extension would be suspended on 16 November 2017 for safety checks on the signalling system. This was then extended to 20 November 2017, when SMRT announced that the TWE would reopen but operate separately from the rest of the line for at least a month. Eastbound trains from Tuas Link would terminate at Gul Circle, while westbound trains from Pasir Ris would terminate at Joo Koon,[17] allowing the two different signalling systems to be isolated until a solution was found.[17] Service between Gul Circle and Joo Koon was suspended on that date and free bus bridging services became available. On 21 November 2017, in a media statement made by Transport Minister Khaw, SMRT and LTA announced that services between Gul Circle and Joo Koon would be further suspended until mid-2018, when signalling upgrades on the remainder of the line are expected to be completed, to prevent another collision in the future.[18]

Early closure on NSEWL

Following the investigation, SMRT announced that operation hours on the NSEWL would be reduced to facilitate more maintenance works and the complete transition to the CBTC signaling system. Starting from 8 December 2017 to 31 December 2017, 17 stations on the East West Line from Tiong Bahru to Tuas Link and 2 stations on the North South Line from Bukit Batok to Bukit Gombak will close early at 11pm on Fridays and Saturdays, while the opening will be delayed to 8am on Saturdays and Sundays, and stations were closed throughout the day on Sundays (10 & 17 December 2017).[19] A second round of closures planned for January 2018 would affect the line from Paya Lebar to Pasir Ris and Changi Airport.[20] In the final round of closures, all stations on the East West Line would close earlier at 11pm on Fridays and Saturdays and open later on Saturdays and Sundays throughout the month, with two days having even earlier closing times. This is to facilitate for additional maintenance works along the line as it switches over to the new CBTC signaling system.[21]

See also

References

  1. ^ a b c "LTA statement in full: Software failure behind Joo Koon collision". Land Transport Authority. Today (online). 15 November 2017. Retrieved 17 November 2017. 
  2. ^ a b c d e f "517 passengers on the moving train in Joo Koon collision". Channel NewsAsia. 16 November 2017. Retrieved 17 November 2017. 
  3. ^ a b c "Joo Koon train collision: Total number of injured rises to 38". Channel NewsAsia. 19 November 2017. Retrieved 19 November 2017. 
  4. ^ a b c d Chai Chin, Neo. "Joo Koon MRT collision: Faulty train was transiting between old and new signalling systems". Today (newspaper). Retrieved 17 November 2017. 
  5. ^ a b c d e Kotwani, Monica (14 July 2017). "North-South Line signalling system to take up to 6 months to stabilise". Channel NewsAsia. Retrieved 17 November 2017. 
  6. ^ a b c d e f Lim, Adrian (16 November 2017). "Joo Koon collision: 'Inadvertent removal' of software fix led to collision". Straits Times. Retrieved 17 November 2017. 
  7. ^ a b Tan, Tam Mei (16 November 2017). "Joo Koon train collision: Some passengers cried and there was vomit in the train, says witness". Straits Times. Retrieved 17 November 2017. 
  8. ^ "28 injured in Singapore metro train collision". South China Morning Post. 15 November 2017. Retrieved 19 November 2017. 
  9. ^ a b c Choo, Cynthia (19 November 2017). "MRT incidents have hurt public confidence: PM Lee". Today (newspaper). Retrieved 19 November 2017. 
  10. ^ a b Tan, Christopher (16 November 2017). "Joo Koon collision: Signal failure hits confidence". Straits Times. Retrieved 19 November 2017. 
  11. ^ "Your views: Aftermath of the Joo Koon train collision". Channel NewsAsia. 19 November 2017. Retrieved 19 November 2017. 
  12. ^ Choo, Cynthia (16 November 2017). "Joo Koon collision points to systems 'failure', WP says in calling for 'exhaustive' checks". Today (newspaper). Retrieved 19 November 2017. 
  13. ^ Kotwani, Monica (15 November 2017). "Khaw Boon Wan apologises to commuters affected by Joo Koon train collision". Channel NewsAsia. Retrieved 19 November 2017. 
  14. ^ a b Ong, Justin (15 November 2017). "SMRT train collision at Joo Koon due to 'inadvertent' removal of software protection feature". Channel NewsAsia. Retrieved 19 November 2017. 
  15. ^ Chia, Lianne (21 November 2017). "2 full-day shutdowns, shorter operating hours for 19 NSEWL MRT stations in December: LTA, SMRT". Channel NewsAsia. Retrieved 21 November 2017. 
  16. ^ Lim, Adrian (22 November 2017). "Protective 'bubbles' became disabled, causing collision". The Straits Times. Retrieved 22 November 2017. 
  17. ^ a b "Joo Koon collision: Tuas West Extension train services suspended until Sunday for further checks". Channel NewsAsia. 16 November 2017. Retrieved 17 November 2017. 
  18. ^ "Joo Koon-Gul Circle link to remain closed till mid-2018". Straits Times. 22 November 2017. Retrieved 22 November 2017. 
  19. ^ "2 full-day shutdowns, shorter operating hours for 19 NSEWL MRT stations in December: LTA, SMRT". Channel NewsAsia. Retrieved 2017-11-22. 
  20. ^ https://www.channelnewsasia.com/news/singapore/sunday-closures-shorter-weekend-service-hours-on-another-part-of-9502414. Retrieved 2017-12-21.  Missing or empty |title= (help)
  21. ^ "shorter operating hours on east west line". Retrieved 20 January 2018. 

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