LTA and SMRT, together with Thales, the supplier of the new signalling system for North-South Line (NSL), have been running tests progressively since 28 March.
2. Phase One of the tests started with the last hour of passenger service on selected weekdays.
3. Since 16 April 2017, we moved into Phase Two of the trials on full-Sunday service and have not experienced any major incident for the past seven weeks.
4. This gave us the confidence to move into Phase Three this week (29 May) which involved full-day weekday trials.
5. At Phase Three, system-level performance checks revealed two unrelated faults: one on Thursday (1 June) during the evening peak and another this evening (2 June).
6. The first incident at 6.20pm on Thursday (1 June) was due to a glitch in the computer server used to manage train schedules. This caused all trains on NSL to halt. Although the back-up server kicked in quickly, operations controllers needed 30 minutes to manually reassign train schedules.
7. Today, (2 June), a signalling equipment known as the Movement Authority Unit (MAU) registered a fault at around 4:48pm. The MAU fault resulted in slower train movement between Kranji and Admiralty stations. Service recovery took some time as engineers needed to troubleshoot and replace components in the faulty MAU. Service progressively resumed just before 8.00pm.
8. Signalling trials are part and parcel of new signaling systems and carried out to help train operators identify and resolve teething problems that may occur. As we continue to intensify the testing of the new signaling system and until the system stabilises, there may potentially be more delays.
9. LTA, SMRT and Thales engineers are intensifying system-level checks. We are very sorry for the inconvenience caused and seek the understanding of commuters.