Commuters should expect a short interruption in their train journeys tonight, when trains on the North-South Line (NSL) stop running for 10 minutes at around 11:00pm. This is to accommodate the first test of a new and upgraded signalling system by the Land Transport Authority (LTA) and train operator SMRT during passenger service hours. During the 10 minutes of stoppage, the trains and the network will be switched over to the new system.

This system will be in use until midnight, when passenger service ends. Thirty trains will be in service during the switchover, and announcements will be made to explain the situation to passengers - both in the trains and on the platforms.

Most trains will pause at the platforms of the 26 NSL stations, with a few on the tracks in between stations. The trains' lights and air-conditioning will continue to work during this period. SMRT added that service staff will be deployed to assist commuters.

SMRT's Director for Station Operations for the North-South and East-West lines, Mr. Siu Yow Wee, said that apart from the delay, passengers should not feel any difference and train services should function normally after the switchover. Tomorrow morning, the old signalling system will be back in use. The LTA said tonight's test will help it decide when to extend trials to longer service hours, and eventually make the full switchover to the new signalling system.

The current fixed-block signalling system has been in use for 30 years, since the NSL started operations. The new Communications-Based Train Control (CBTC) system will allow trains to run closer together, and arrive at intervals of up to 100 seconds during peak hours, instead of 120 seconds currently. Train doors will also open and close automatically, instead of being controlled by the train captain.

Transport Minister Khaw Boon Wan said earlier this month that there could be teething problems with the new system. Singapore Institute of Technology Assistant Professor Zhou Yi said the new CBTC system relies heavily on communication between various equipment and devices. He noted that testing during passenger service hours was indeed necessary. "Operations during passenger service can be different. For instance, the commuters' weight will dynamically affect the total mass of the train, which affects the speed control," he said.