Testing of the new signalling system on the East-West Line - currently conducted only after the line closes to the public for the day - will soon be extended to normal operating hours, said Transport Minister Khaw Boon Wan yesterday.
This means that commuters should expect "glitches and delays", he said in a Facebook post, adding: "I urge commuters to bear with us and thank them for their patience."
Such testing has already been conducted on the North-South Line (NSL) during normal hours, but the upcoming tests mark the first time it will also be done on the East-West Line (EWL) - an indication of the progress of re-signalling works. Works are due to be completed in June.
Mr Khaw said in his post that the transport workers are focusing on the re-signalling of the EWL, now that the new signalling system on the NSL has stabilised.
"Learning from the NSL experience, we are intensifying testing of the system, without passengers," he wrote.
Mr Khaw, during the debate on his ministry's spending plans in Parliament last week, had similarly pointed out the need to start testing the new signalling system of the EWL during passenger service hours. He had noted this as "bad news", but said the "good news" was that the NSL, which had already started running on the upgraded system, was poised to cross its 150th consecutive day of no disruptions.
In his Facebook post, Mr Khaw also shared photos of his recent visit to train operator SMRT's Operation Centre, where he observed testing of the new communications-based train control signalling system on the entire North-South and East-West Line (NSEWL) network.
The system allows trains to run more frequently, thus increasing capacity and easing congestion.
"Testing allows us to calibrate and tune the signalling equipment on each train. That is why re-signalling is so complicated and time-consuming," Mr Khaw explained.
"That is why the #ECLO (Early Closure, Late Opening) is so useful to us," he added, referring to the move since December to shorten operational hours on the entire NSEWL network on weekends to cater more time for renewal and maintenance work.
This month, stations will open later at 8am and close early at 11pm every weekend until April 1.
Today and on Wednesday, during the March school holidays, the EWL stations will also close earlier at 10.30pm.
Trains usually run from 5.30am to about midnight daily.
Mr Khaw noted that the extra engineering hours provide engineering staff with longer blocks of time on the train tracks.
"With ECLO for the entire EWL, we are also able now to test the new system for the entire line, and not just partial stretches," he added.