SMRT will be stepping up checks and replacing rails earlier after a recent spate of four rail cracks in the last five weeks, the latest occuring on Friday night.

The measures were announced at a joint media briefing by SMRT and the Land Transport Authority on Saturday afternoon.

In the short term, SMRT will be prioritising inspection of curved track segments. All four cracks, which occurred on April 29, May 18, Thursday morning and Friday night, were all on curved tracks. Ultrasound checks will be conducted on a further 246 rail joints.

Some 40km of rail will be replaced earlier, out of the total 400km route length of the North-South and East-West lines. The new regime will see rails replaced once they have been worn down by 12mm, instead of 14mm.

To speed up this replacement, SMRT is looking to expand its workshop facilities in the longer term.

LTA will be appointing an international trackwork specialist to assess the condition of the rails. It will also be auditing SMRT's maintenance works fortnightly instead of monthly.