THE Land Transport Authority (LTA) has launched an investigation into a two-hour disruption on the North East Line (NEL) on Wednesday evening.
Following the chaos caused by the stoppage, LTA said it will look into operator SBS Transit's management of the incident, "including rescue and detrainment of affected commuters".
A spokesman said it will also investigate the cause of the train fault, which left 250 commuters stranded on a train for about an hour and affected 50,000 passengers. The train travelling towards HarbourFront stalled as it approached Hougang station on Wednesday evening.
SBS Transit deployed a second train to push the stalled train to the nearest station - a standard recovery procedure - but could not move it despite repeated tries.
Services were disrupted between Woodleigh and Punggol for about two hours, with passengers having to complete their journeys on free shuttle buses.
When asked about the cause of the train stalling, the failed recovery operation and the transport operator's handling of the incident, SBS Transit spokesman Tammy Tan would only say investigations were ongoing.
The NEL had an average daily ridership of more than 450,000 last year.
An expert on trains who declined to be named said it was possible the stalled train's brakes could not be released as designed, thus preventing the rescue train from moving it. Some signalling control could also have restricted movement, he said.
Banking officer Vivien Chionh, 43, who had to get out at Woodleigh, said there were hundreds of people milling outside the station, and the scene was chaotic.
There were not enough station employees to guide commuters, nor signs to say where the shuttle bus pick-ups were, she added, and the buses that arrived were full. It confirmed what other commuters had said.
In a strongly worded Facebook post, Transport Minister Lui Tuck Yew said he expected SBS Transit to manage such incidents much better in the future.
National University of Singapore transport researcher Lee Der Horng noted the difficulty bus services faced in coping with the sheer numbers of rail passengers.
Even so, he said, transport operators have to equip themselves for such situations: "In this incident, they (SBS Transit) have not done enough."