Train services along parts of the North-South and East-West lines will start up to an hour later on Sundays to give engineers more time to carry out maintenance works.
Stations open at different times but full services will be up by 7am.
The later start times will affect 13 stations from June 5 to Dec 18, excluding public holidays.
The stations are between Joo Koon and Queenstown on the East-West Line (EWL), and between Bukit Gombak and Jurong East on the North-South Line (NSL).
In Parliament on Tuesday, Transport Minister Khaw Boon Wan called for commuters to allow operators to open some of the MRT lines a bit later in the morning to facilitate maintenance works.
Operator SMRT said yesterday the later starts will give staff more time during engineering hours - when trains are not running - to carry out works, including replacing sleepers and upgrading the power-supplying third rail. Maintenance teams now have only three to four hours each night. "The later opening will enable these teams to gain the equivalent of 29 additional maintenance nights over the six-month period," SMRT said.
SMRT has advised commuters who need to travel earlier to use bus services to get to other train stations, or use the Circle and Downtown lines to get to the city. A parallel bus service between Joo Koon and Bukit Gombak will be launched. Details of the route and fares will be released in the next few weeks.
SMRT has also been closing stretches of the EWL - between Tanah Merah and Pasir Ris stations, and between Joo Koon and Jurong East stations - half an hour earlier. It has advised commuters who board EWL trains after 11.15pm to check last-train times. The early closures, which will last till end-August, are from Sundays to Thursdays, except on the eve of public holidays.
Giving an update on its rail upgrading works yesterday, SMRT said it had replaced half of the 92,000 timber sleepers on the EWL with concrete ones. Sleepers are used to hold the tracks in place.
An earlier project to upgrade the 96,000 sleepers on the NSL was finished in April last year.
An ongoing project to upgrade the signalling system on the NSL is about 96 per cent completed, and at 67 per cent on the EWL. Upgrading the signalling system allows trains to run at shorter intervals of 100 seconds during the peak hours, instead of 120 seconds currently.
To reduce power-related faults, the ageing third rail is also being replaced. SMRT said about 27 per cent of the work for the EWL has been completed, while work for the NSL is 6 per cent completed.