SINGAPORE - Train service on the North-South Line was delayed slightly on Thursday (July 20) evening when workers fixed a loose clamp on the rail.

After a quiet spell following a software patch to fix glitches in a new signalling system, the line experienced a delay at around 5.30pm when SMRT workers tightened a clamp on the running rail northbound of Choa Chu Kang station.

The clamp - put in place for more permanent repairs to be done later in the night after service hours - had come loose, and had to be tightened for safety reasons.

The entire exercise took slightly over 10 minutes, and delayed the service of around four trains.

On Wednesday night, a train fault near Newton station affected service on the same line.

Neither event was related to the new signalling system, which is still being tested for bugs. The software patch - a piece of software designed to update a computer programme to fix or improve it - was installed last Friday night.