A signalling fault caused train delays along the North-South Line yesterday, SMRT said.
The rail operator sent out a tweet around 8am, advising commuters travelling from Newton to Marina South Pier to expect an extra 30 minutes of travel time.
Regular bus services ran for free from the affected stations.
On Monday, there were delays on the East-West Line, due to a track fault at Clementi.
In response to a Straits Times query, SMRT said that yesterday's incident involved a signalling fault with a train travelling towards Yishun in the morning.
Mr Patrick Nathan, SMRT's vice-president for corporate information and communications, said: "It was subsequently withdrawn from service after passengers disembarked at Raffles Place. We are sorry for the inconvenience caused."
Around 8.30am, SMRT sent an update, saying the fault had been cleared and train speeds were returning to normal.
When ST spoke to 10 commuters at Raffles Place station around 9am, some said their rides were slower and jerkier than usual.
Three commuters said they were directly inconvenienced by the delays.
Bank employee Eileen Lee, 38, took 15 minutes longer on her commute to work.
"It has become such a norm that the train will stop in between stations," she said.
"Disruptions have happened all the time in the past one to two years, so people have stopped complaining."