After a trouble-free week that followed a mysterious signalling interference which led to longer train journeys, a major disruption on the Circle Line affected tens of thousands of commuters for more than three hours yesterday.
The breakdown, traced to a track switch fault between the Paya Lebar and MacPherson stations, was the single worst rail disruption in five months.
Operator SMRT was unable to shed more light on the fault beyond saying it was on the same track switch that was hit by a glitch on Sept 5 from 8.30pm to 9.15pm.
Commuters who were affected yesterday included public relations executive Ashley Wu, who said she was late for work by half an hour.
"I take the Downtown Line from my home in Bukit Panjang to change to the Circle Line at Botanic Gardens," said Ms Wu, 35.
"When I got to Botanic Gardens, the station was just so crowded. People were rushing and pushing... I could board only the fourth train."
Ms Wu said the information was not comprehensive or given quickly enough, and that she would have made alternative arrangements if she knew about the glitch before taking the Downtown Line.
"Breakdowns are inevitable, but SMRT needs to communicate better and also support affected commuters with breakdown slips which they can show their employers," she said. "My company is strict about punctuality. And I'm sure many out there are as well."
She said she lived in Japan for two years, and it is a practice to give out such breakdown slips there.
SMRT first tweeted about the glitch at 6.57am, warning of five minutes in additional travelling time. At 7.06am, it said the fault had been cleared.
But barely 10 minutes later, it said travelling time from Dhoby Ghaut to MacPherson would be five minutes longer. This was revised to 10 minutes at 7.34am, and to 15 minutes an hour later.
At 9.53am - nearly three hours after the fault occurred - SMRT told commuters to expect an additional 10 minutes of travelling time from Dhoby Ghaut to Bishan.
Free regular bus service between Paya Lebar and Bishan was made available. At the height of the disruption, SMRT staff at Bishan station were overheard suggesting to commuters that they take other MRT lines to get to Dhoby Ghaut.
Then, at about 10am, SMRT tweeted to say regular service had resumed. But between 10.30am and 11am, The Straits Times found that Dhoby Ghaut-bound trains at the Serangoon and Bishan stations were still arriving at intervals much longer than that for HarbourFront- bound trains, and train arrival notifications were not available at the stations.
The Circle Line was hit by a mysterious signal interference between Aug 29 and Sept 5. The yet-to-be determined interference caused trains to apply emergency braking intermittently, leading to longer and jerkier journeys for a week. The problem stopped as suddenly as it started.