SINGAPORE - The launch of an upgraded signalling system on the North-South Line - which will allow trains to run at shorter intervals - will be pushed back to the first quarter of next year (2017).

More testing is required for the new system, which can enable trains to arrive at 100-second intervals instead of 120 seconds currently, the Land Transport Authority (LTA) said on Wednesday (Oct 26).

The upgrading project started in 2012 and was earlier slated to be completed by the end of this year. By allowing trains to travel more closely together, passenger capacity on the North-South Line will be increased and crowding reduced.

The LTA said that as a precautionary measure, it will "devote more time to do more extensive tests to ensure the reliability of the system before launching it".

More thorough testing was also the advice given by rail operators from other cities, such as in Taipei and London, which had upgraded their signalling systems previously, the authority added.

The North-South Line, along with the East-West Line, are Singapore's oldest MRT lines, having launched in 1987, and this is the first time their signalling systems are being updated.

The LTA said that for the North-South Line, works to install the new signalling equipment on trains and tracks, as well as in stations have been completed. On the East-West Line, these works are more than 80 per cent complete.

For the North-South Line, 93 per cent of the testing for the new signalling system has been completed.

The authority, along with operator SMRT, expects to perform more than 1,300 tests in total, which include ensuring that train doors are accurately aligned with platform screen doors when trains come to a halt at stations. Trial runs during off-service hours have also been ongoing since August.

Engineering staff only have between two to three hours every night, during off-service hours, to perform these tests.

The LTA also said on Wednesday (Oct 26) that the new Tuas West Extension - a 7.5km, four-station segment extending from the East-West Line's Joo Koon MRT - will open in the second quarter of next year.

The authority had earlier aimed to open the new section at the end of this year, but as the extension also uses the new signalling system, more time will be required for testing.

The LTA expects to launch the new signalling system on the East-West Line in 2018.