North-South Line signalling system to take up to 6 months to stabilise

North-South Line signalling system to take up to 6 months to stabilise

The new signalling system on the North-South Line (NSL) will take between four and six months to stabilise, the Land Transport Authority (LTA) and SMRT said on Friday (Jul 14).

SINGAPORE: The new signalling system on the North-South Line (NSL) will take between four and six months to stabilise, the Land Transport Authority (LTA) and SMRT said on Friday (Jul 14).

But a software update to be installed on Friday night is expected to address glitches, some of which have resulted in multiple train disruptions since full-day tests on the new signalling system started in late May.

About 1,400 engineers and staff will be on standby round the clock to monitor the situation, as the train operator said it cannot rule out initial faults during the software update. Thales, the supplier of the signalling system also has more than 150 staff working with SMRT and LTA.

As for the East-West Line (EWL), SMRT said it hopes to test the new signalling system during passenger service sometime during the December school holidays, to ensure minimal impact to commuters.

These updates were given during a media briefing which was co-chaired by LTA CEO Ngien Hoon Ping.


SMRT Trains CEO Lee Ling Wee said it is important that the system is stress-tested “rigorously” during passenger service to resolve teething problems.

“This is a necessary process that we must undertake because the NSEWL (North-South East-West Line) is an operational line,” Mr Lee said.

However, it also resulted in signalling faults and rush-hour delays that affected commuters on two consecutive days in June. SMRT explained that one glitch that came up during the testing had to do with the alignment of train and platform doors on rainy days, when trains stop at above-ground stations.

With 60 per cent of stations on the North-South Line above ground, SMRT said alignment issues need to be manually realigned so that the train doors open and close in sync with platform doors.

To address this, it has reduced the speed of trains when nearing stations on rainy days. The software upgrade scheduled for Friday night will also “better calibrate and synchronise alignment”.

SMRT said another reason for delays and congestion is due to the fact that the North-South Line is now running on the new signalling system, while the East-West Line is still on the existing legacy system.

Explaining this, SMRT’s senior vice president for Rail Operations (NSEWL), Alvin Kek, said that in order to operate the NSL, trains have to be launched from both Bishan depot and its Ulu Pandan depot. Bishan is on the NSL, which means trains coming from there continue to operate on the new signalling system.

The Ulu Pandan depot, on the other hand, is on the EWL, which means that when trains are launched from Ulu Pandan to Jurong East station, trains have to be switched from the old signalling system to the new one.

“This switch at Jurong East station takes about one-and-a-half minutes, and in the morning with a headway of about two minutes, it does cause delays and congestion and impacts commuters’ journeys,” Mr Kek said.

He added that the same switch needs to happen with the Tuas West Extension. To mitigate such delays, SMRT has opened the Jurong East Platform A an hour earlier than the typical 8am timing. He said the earlier operating time for the platform has addressed the launch and time delays incurred for switching the signals and has also eased congestion.

Mr Lee said so far, data shows delays due to teething problems over the new signalling system have reduced in the past weeks, and it is hoped that the software upgrade will improve the situation.

He also pointed out that not all incidents over the past few weeks are due to signalling faults. For instance, the disruption on Wednesday (Jul 12) between Jurong and Clementi station was due to a track circuit failure, and is not related to the new signalling system on the NSL and Tuas West Extension. 

SMRT said another incident on Jun 28 was due to human error during a software implementation process. 


In testing the system during passenger service, SMRT and LTA said they were mindful that the process should be progressive, with minimal inconvenience to commuters.

SMRT said after lab tests were conducted on the new signalling system, it was rolled out on the Changi Airport Line.

The system underwent 10 sessions of testing from 11pm onwards from the end of March, and in mid-April, it was tested on Sundays, starting with 41 trains, 50 and subsequently 61 trains.

It said that as a precaution, all the 140 trains are fitted with both the old and the new signalling system, should there be a situation in which they need to be reverted to the old signalling system.


Despite the system being rolled out progressively, delays caused by signalling glitches raised questions as to why SMRT was carrying out tests during the day, including at peak hour.

LTA’s CEO Mr Ngien reiterated that a "full load" test is inevitable to understand how the system runs. Compared to cities like London, where entire lines were partially closed for weeks during its system testing, Singapore cannot afford to do that.

Instead it took the "progressive" approach, including testing out the system during its engineering hours of between 1:30am and 4:30am.

But he said that if the system was only tested during this time window, it would take many years before the system is implemented. That’s because other maintenance works and projects to the rail network are also carried out in the same time.

Additionally, the signalling system change has also required upgrading works to some 95km of track, 140 trains and almost 55 stations.

Still, when the system stabilises over the next few months, a better commute can be expected, Mr Ngien said. SMRT expects the system on the NSL to be fully operational by May 2018, a year from when testing during passenger service started.

The new communications based train control (CBTC) signalling system is expected to improve waiting time for trains, as it will allow a safe reduction in distance between trains travelling on the network. This means more trains can be packed during service hours.

SMRT said testing of the EWL has started on some stations during engineering hours, and once the NSL signalling system stabilises in the next few months, it hopes to begin testing the signalling system on the EWL in December. 

Source: CNA/cy