SINGAPORE: The collision between two Mass Rapid Transit (MRT) trains that resulted in 28 people being injured was caused by a software problem on one of the trains.
Singapore's Land Transport Authority (LTA) deputy chief executive (infrastructure and development) Chua Chong Kheng said that a faulty signalling system on the MRT East-West Line had inadvertently removed a software protection feature on the first of two trains which had came to a halt at the Joo Koon MRT station in Jurong East.
This train was in front of the second train which would later also stop at the same station.
The second train was supposed to come to a complete stop 10.7m behind the first train.
But the software glitch caused the second train, which local media estimated was carrying 517 people, to incorrectly detect the first stalled train as a three-car train instead of a six-car train, thus leading to the collision.
"The preliminary finding was that the first train, which departed from the Ulu Pandan Depot with a software protection feature turned on, had the feature inadvertently turned off 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 as 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," said Chua.
In explaining what occurred prior to the collision, Chua said the first train stopped and detrained passengers at the Joo Koon station at 8.18am yesterday due to an anomaly in the train signalling system.
"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," he said.
Chua said that Thales, the supplier of the signalling system has confirmed the old and new signalling systems used along the East-West MRT Line continue to be safe for operation.
He said that the Joo Koon to Tuas Link route of the MRT would be temporarily suspended today (Nov 16) as checks were being done by Thales.
"As a precautionary measure, trains will go through an additional layer of control measures and manual checks before they are deployed," he said.
Singapore's Transport Minister Khaw Boon Wan told local media that he ordered for the closure of the Joo Koon-Tuas Link route (Tuas West Extension) which spans five stations to allow for a very thorough check.
"It's an awful day today. Commuters were inconvenienced, and some even injured. We are deeply sorry for that."
"Thales is confident of their system, but I advised the team, let's play doubly safe, where safety is involved, that's why I want them to suspend the Tuas West Extension on Thursday, so we have a whole day to do a thorough check before we resume the Tuas West Extension," Khaw told the Straits Times.