Commuters travelling on the North-South Line (NSL) yesterday were stranded after a signalling fault on the 30-year-old line caused delays for two hours during the evening peak period.
At 6.18pm, SMRT first cautioned commuters to expect an additional 20 minutes' travelling time between the Yishun and Marina South Pier stations, due to a fault with the new signalling system near Ang Mo Kio.
Nearly half an hour later, the additional travelling time was updated to 25 minutes. This was further increased to 40 minutes at 7pm.
Mr Lim Chia Wei, 21, was on his way from Novena to Bishan when the train stopped at Braddell for 15 minutes. "The door opened and did not close," said the student, adding that it was "extremely crowded" at the Bishan station when he got there.
Though the delays were said to be on the 16-station stretch between Yishun and Marina South Pier, commuters complained of delays affecting the entire 44km-long rail line.
Photos and videos posted on social media showed packed train platforms at the Jurong East interchange station - at the other end of the line from Marina South Pier.
Free bus services, including buses plying between train stations, were provided for commuters between Marina South Pier and Ang Mo Kio in both directions during the delays.
On its Facebook page, SMRT said a signalling unit along the tracks near Ang Mo Kio experienced a fault at about 5.35pm, affecting signalling communication to trains. "A joint team of engineers are working to rectify the signalling fault on the North-South Line," it later said, and advised commuters to travel on other lines or make alternative transport arrangements.
Train services were back to normal at 8.15pm.
SMRT apologised for the "difficult evening for affected commuters". It said: "Our engineers continue to closely monitor the system for the rest of the night, and investigation works will continue after service hours."
Full-day tests of the new signalling system on the NSL, which will allow trains to run closer together, began in May. Since then, there have been numerous delays on the line. The Land Transport Authority and SMRT have said full-day tests of the signalling system on weekdays "cannot be avoided" as they allow for problems to be quickly identified and resolved.
Last month, a software update developed by French firm Thales, the contractor in charge of the $195 million resignalling project on the North-South and East-West lines, was rolled out to address some of the "teething issues" that had affected the new system.
At a forum organised by SMRT last month, Coordinating Minister for Infrastructure and Minister for Transport Khaw Boon Wan said that the new signalling system should stabilise by year end "if there are no new surprises", with tests of the new system on the East-West Line to follow.
•Additional reporting by Clara Chong