Train services on the East-West Line between Bugis and Tanah Merah stations will end up to half an hour earlier from Sunday to Thursday, starting from Nov 15 until the end of the year.
The early closure, involving nine stations, is to give operator SMRT more time to replace timber sleepers - used to hold the tracks in place - with more durable concrete ones.
Train services will run normally on Fridays and Saturdays as well as on the eve of public holidays.
This is the first phase of the early closures on the East-West Line, on which 92,000 timber sleepers will be replaced. The second phase, which will affect stations between Joo Koon and Jurong East and between Pasir Ris and Tanah Merah, will start early next year.
The final phase, affecting stations between Jurong East and Outram Park, should be completed by early 2017.
About 96,000 timber sleepers have been replaced with concrete sleepers on the North-South Line.
Sleeper replacement is necessary because the "rise in ridership and increased train services have added stress on our ageing infrastructure", SMRT said. This is part of the rail operator's maintenance regime. It will also replace the third-rail power system by 2017.
Sagging sections of the third rail, which supplies power to trains, were singled out as the main cause of two major breakdowns on the North-South Line in 2011.
Last month, SMRT was fined $5.4 million for a massive breakdown that crippled both the North-South and East-West MRT lines during the evening peak period on July 7.
Lim Yi Han