Joo Koon train collision: LTA responds with preliminary finding

An investigation by Thales, the Land Transport Authority (LTA), and SMRT regarding the train incident at Joo Koon MRT Station on Wednesday morning (Nov 15) showed that a faulty signalling circuit had removed a software protection feature on the first train, which led the second train to mistake it as a three-car train instead of a six-car one. 

This, in turn, caused the second train to misjudge the distance between the two and resulted in it colliding into the first train.

An official statement by the LTA read:

“This morning at about 8.18am, a train heading in the direction of Tuas Link Station stopped at Joo Koon Station to detrain passengers due to an anomaly in the train signalling system. 

“At 8.19am, a second train stopped 10.7 metres behind the first stationary train. 

“This is in accordance with the safety protocol of the signalling system protection that ensures safe stopping distance between two trains. 

“At 8.20am, after detrainment, the first train’s doors closed and before this train could move off, the second train, activated by the signalling system, moved towards the first train and hit it. 

“Thales, LTA and SMRT are investigating the incident.

“The preliminary finding was that the first train departed Ulu Pandan Depot with a software protection feature, but the feature was inadvertently removed when the first train passed by a faulty signalling circuit. 

“This train then arrived at Joo Koon station without the feature. The removal of this feature resulted in the first train giving off a train profile on the new signalling system of a three-car train instead of a six-car train. 

“As a result, the second train detected the first train as a three-car train and misjudged the distance between the two trains, therefore resulting in the collision.

“Thales has confirmed the old and new signalling systems continue to be safe for operation. 

“The East-West Line is currently running on the old signalling system from Pasir Ris to Pioneer, and the new signalling system from Joo Koon to Tuas Link. 

“As a precautionary measure, trains will go through an additional layer of control measures and manual checks before they are deployed. Operations from Joo Koon to Tuas Link will also be suspended on 16 Nov 2017, while we conduct assurance checks with Thales. 

“Bus bridging will be deployed for the affected stretch for the duration of the suspension.”