In their closing report released yesterday (Dec 19), the Land Transport Authority (LTA) concluded that SMRT and the government is not responsible for the train collision incident that injured 38 passengers. Pushing all blame to the signalling system supplier, Thales, LTA said the bug in their software is the main cause:
“A “software logic issue” with the new signalling system and a “confluence of failure conditions” caused the train collision at Joo Koon MRT station on Nov 15, 2017… Thales has acknowledged its responsibility for this incident, and has apologised to the public.”
However, there will be no punishment for Thales or SMRT.
LTA yesterday explained in details about the software glitch saying that they overlooked the integration testing between the two signalling system:
“The collision arose from an “abnormal condition” on a train-borne CBTC signalling equipment. When this occurs, the CBTC system will, by design, apply a Non-Communicating Obstruction (NCO) protective ‘bubble’ around the affected train to ensure its safety. This was the requisite start state for the incident,” LTA said. However, the train crossed “the only track point” that has not yet been fully modified for compatibility with the CBTC system. The protective “bubble” was then “unexpectedly disabled” by the CBTC system, “as the software logic cannot correctly process a track point that has yet to be fully modified for compatibility with the CBTC system when running in passive mode. This is not an issue when the CBTC is running in active mode on the North-South Line and the Tuas West Extension (TWE) as they are fully on the CBTC system.”
Thales also announced that they will build a simulation facility to conduct more testings without having to use real-time operations for testing and data logging.
The Singapore government also said that they “reserve the rights” to take actions against “relevant parties” involved in the incident, but did not explain what actions will they be taking.