The mysterious signal interference which interrupted service on the Circle Line MRT two months ago is back. Thousands of commuters were affected during the morning crush yesterday when an "intermittent signal fault" persisted for three hours from around 7.30am.
At one point, service ground to a halt for more than an hour in the northern stretch of the line, affecting five stations between Botanic Gardens and Serangoon. On other parts, journeys were delayed by 20 to 30 minutes up to past 10am.
The disruption had a ripple effect as stranded commuters took to taxis and private transport, adding to peak-hour traffic on the road.
Motorist Chester Chong said he took an hour and 20 minutes to get from Teban Gardens to Bartley, a journey which usually takes 45 minutes or less.
"I was stuck on the PIE (Pan-Island Expressway) for 45 to 50 minutes," the 31-year-old sales consultant said. "When I reached the Braddell flyover, I could see a huge jam in the other direction."
SMRT said that preliminary findings revealed a communications glitch similar to the one which disrupted service on the line for a week in late August.
The first incident was traced to an unknown signal interference which disappeared as mysteriously as it appeared - before the source could be established.
In a joint statement yesterday, SMRT and the Land Transport Authority (LTA) said they had arranged with the Infocomm Media Development Authority and mobile network operators "to suspend telecommunication signals along stretches of the line for short periods of time to assist in investigations". This is to establish whether telco signals are behind the interference.
They also said the driverless Circle Line trains "will be manned during evening peak hours".
SIM University senior lecturer Park Byung Joon said: "They have to find the source of this interference. The system is not a living organism. It won't heal itself. So unless they find the fault and fix it, it will remain."
Meanwhile, many commuters reached their destinations far later than usual.
IT consultant Davis Li, 32, was stuck in a train for an hour and 45 minutes when it stalled between Caldecott and Marymount stations.
"I got on at 8.15am, and the train started to move again only at 10am," he said.
He reached his workplace in Bishan at 10.30am - 90 minutes late.
Mr Li said it was the worst breakdown he has been caught in, but was nonchalant about it.
“There was nothing much we could do. Fellow passengers were helpful to one another, asking the elderly to sit down, and I saw someone asking a child if he was hungry.
“Someone in front shouted to ask if anyone needed medical attention. One uncle called the LTA to complain, and another pressed the communication button onboard but there was no response.”
Undergraduate Denise Tan, 21, said she was late for class despite spending $33 on a cab which she managed to secure after 20 minutes. She usually takes the train from Bartley to Kent Ridge station.
“I asked the station staff about the situation but no one could tell me anything,” she said. “They don’t even inform incoming passengers.”
Student care teacher Bryan Lee, 33, said he was delayed for 20 to 30 minutes. "I left my house at around 9.40am to get to Bishan station. When I found out about the breakdown, I went up to catch the free bus," he said. "Then I heard the announcement that service had resumed, so I went back down again."
Free buses were activated along the line but the roads, too, were congested.
The latest disruption occurred despite the LTA announcing on Sept 21 that it was planning to prevent a repeat of the signal interference through steps such as fitting trains with an electromagnetic shield.
Meanwhile, service on the East-West Line lapsed during the evening peak period.
SMRT tweeted at around 5.45pm that there was no service between Queenstown and Outram Park stations towards Pasir Ris because of a train fault at Tiong Bahru station.
Free buses were activated.
The stalled train was cleared at around 6.20pm but free buses were still available, SMRT said.