Communications-based, Communications-lost. Why it went off track.

It has been about 10 months since the CBTC system started testing. This highly complex yet necessary upgrade to the aging North South & East West Lines (NSEWL) has encountered many setbacks which we will discuss in the following blog post.

The views expressed are our own personal views based on our observations and does not reflect the views and/or opinions of the Land Transport Authority, SMRT or Thales. While every effort has been made to ensure the accuracy of the blog post, we cannot guarantee that the information stated is accurate and will not accept liability for any errors, omissions or misleading statements.

1. Implementation of the new system

Prior to the testing of the CBTC signalling system on the North South Line (NSL), the CBTC had first commenced its trial as a Proof of Concept (POC) on the Changi Airport Line – which is a branch of the East West Line (EWL). Chosen due to its short length, it was the ideal line to trial the system on before implementing it to the other lines once it was proven successful.

After it had been deemed stable, the CBTC was introduced on the NSL. The NSL launched its CBTC testing on 28 March 2017 at 11pm – while the line was still in passenger service – during which the entire NSL halted operations for a full 10 minutes to allow a switchover to the new signalling system. Starting with operations only on Sundays, the CBTC system eventually progressed to full daily operations.

A train halted operations for a full 10 minutes at Woodlands station to allow a switchover to the new CBTC signalling system.

Introduced as an entirely new system, the CBTC is a highly complex, yet necessary upgrade to the aging NSEWL. The passenger volumes that these arterial lines handle daily are on a steady rise, following our increasing population. With the new signalling system, train frequencies can be improved, increasing the maximum capacity of the lines and making them future-proof. The CBTC also allows for a fully automated system, improving the regularity of train frequencies.

The upgrade of the MRT signalling system is unlike a simple software update on our Personal Computers. It is highly complicated, involving multiple sets of complementing software programmes and infrastructure. Even the oldest trains in the fleet, built between the years 1986 – 1989, were required to undergo upgrading to be compatible with the CBTC.

Employees from both the regulator and operator were sent overseas for a few months to the Thales Transportation Headquarters in Canada to learn and understand the CBTC system. This was necessary as employees needed the knowledge and information of this new system and pass it on to the staff in Singapore, implementing the CBTC according to our local infrastructure.

Meanwhile, the new Kawasaki-Sifang C151B trains (stickered in orange, red and black livery) were designed only to operate under the new CBTC and as a result, were not able to operate on the NSEWL while it was using the older legacy signalling system. Despite the new trains being delivered to Singapore in 2015/16, these trains were only rolled out on 16 April 2017, as the full day CBTC testing on Sundays commenced on the NSL.

2. Problems faced

The initial implementation of the CBTC on weekdays was chaotic and plagued with teething issues. At times, train doors closed without warning and occasionally the system would glitch and cause delays or even disruptions to train services. Up till today, some issues have yet to be resolved.

These issues, while not critical and concerning safety , are still a cause of concern. One recurring issue is that of older generation trains failing to apply electric brakes while stopping at stations. Without the use of electric brakes – hence only friction brakes applied – the train’s brake pads wear off faster, giving off a burning odour that commuters often express concern over, via SMRT’s feedback channels.

Burning odour that commuters often express concern on SMRT Facebook page.

Another problem is an issue related to the in-train announcements that has been observed since the CBTC was implemented on the NSL early last year.

Based on our understanding on the issue, there are interferences between the legacy and CBTC systems, which causes abnormalities in the train-borne announcement equipment. There would be instances where announcements are played repeatedly, cut off, or played randomly out of sequence. Different trains are observed to have various occurrences of this abnormality, mostly occurring at underground interchange stations on the NSL between Bishan and Marina South Pier.

The in-train route-maps would also display erroneous information on the present location of the train and scroll unrelated information on the vacuum fluorescent displays.

The teething issues that had surfaced had been gradually ironed out and in general, the whole system has progressively stabilised over time as compared to its initial testing period.

There have been multiple delays that were caused by glitches on the new system’s hardware and software. These problems led to a range of inconveniences to passengers, from minutes of delay, to severe crippling of sections along the lines. For instance, in mid-2017, there were several instances of major signalling faults affecting the NSL during the weekday peak hours.

Queue lines were placed at underpass linking Bishan NSL, where passengers had to queue for a Northbound train during the weekday evening peak hours, similar to a queue for an amusement park ride. The platform often faces overcrowding problems as the train headways are unstable and are at times unable to cope with the large volume of passengers transferring from the Circle Line.

Passengers queueing for a Northbound train at Bishan NSL underpass.

Notably, the collision at Joo Koon station on 15 November 2017 was a result from a severe miscalculation in distances by the CBTC, after its signalling transition at Pioneer station. The incident led to a halt in the progress of the CBTC, while authorities stepped in to assess the conditions that led to the unprecedented nature of the accident.

Two trains collided at Joo Koon MRT station (Photo: Jonathan Choo, Straits Time)

3. East West Line CBTC

The Tuas West Extension (TWE) on the EWL commenced operations on 18 June 2017, with the new stretch utilising the CBTC.

The authorities rushing the implementation of the CBTC on the NSL and the opening of the TWE – when it was still clearly unstable – was a major oversight on their part. TWE opened to much fanfare in June 2017, only to be isolated from the rest of the EWL just 5 months later in November 2017. The segregation of Gul Circle and Joo Koon was done because both ends operated under different signalling systems. Ironically, a portion of the cost saved on single fitting the TWE is now spent on deploying shuttle buses daily to ferry passengers between Joo Koon to Gul Circle. The extension was not planned to be dual fitted with both the old and new signalling system as the authorities probably did not forsee that the entire project will be delayed.

4. Our opinions

Amidst the progress made, some considerations could have been better managed for the transition into the CBTC signalling system.

Firstly, the weekday testing of the CBTC was overly rushed and launched hastily without full consideration of peak hour commuters. The CBTC testing could have been trialled through more phases over a longer period. This may allow for a more progressive yet comprehensive analysis of the system before it finally operates in peak-hour conditions. They could have done it by introducing the system test from full day tests on Sundays only, to both Saturdays and Sundays. If there were any issues, the number of passengers affected will be significantly reduced. Once the system proves to be stable enough, it should then be rolled out to weekdays.

If there was really a need to push the CBTC into weekday testing at this stage, there should have been parallel bus services deployed along the NSL corridor during the initial phase of testing to alleviate the situation should train services be disrupted. Also, fares along the NSL could be waived should there be delays of above 15 minutes, making the journey less frustrating for commuters.

Based on what we observed overseas such as Kuala Lumpur’s Sri Petaling Line, which is also using the Thales SelTrac system, trains from Pasir Ris with the old signalling system could end at one platform at Joo Koon, while trains from Tuas Link with CBTC could end at the other platform. We are unsure if there are any technical constraints with operating each platform at Joo Koon with a different signalling system, however, while it still segregates the 2 signalling systems, commuters can simply alight and cross the platform at Joo Koon to continue to their destination on the respective trains.

A diagram of how both the legacy and CBTC signalling system operates.

Platform A
Joo Koon to Pasir Ris (WS – Old legacy signalling system)

Platform B
Joo Koon to Tuas Link (CBTC)

During peak periods when there are more trains running, single platform operations at Joo Koon may not be able to handle the number of trains coming in from Pasir Ris. This can be overcome by turning back trains at Boon Lay, which is done frequently when a fault occurs near Joo Koon.

The Tuas West Extension (TWE) should have not been built with only the CBTC, especially when the EWL was not planned to migrate to the new system by the time the TWE opens in the year 2016/17. Dual fitting the TWE with the old and new signalling systems would increase the cost of the extension, but doing so would have eliminated many technical and operational issues after opening.

Alternatively, the authorities could have planned to finish re-signalling on the EWL first, instead of the NSL. Passenger testing could have been done on Changi Airport Line to iron out teething issues before implementing it to the rest of the EWL to reduce delays, disruptions, and inconveniences to the main passenger network.

Since December 2017, stations along the NSEWL will close earlier on Fridays and Saturdays, and open later on Saturdays and Sundays. The additional hours will allow renewal projects and maintenance work to be carried out for up to 7.5 hours each night, doubled from 3 hours on other days. There will also be full Sunday closures on these stretches.

Roller shutters were down at Pioneer station during the full Sunday closures.

With extended engineering hours, the completion of re-signalling works on the EWL will be significantly accelerated from December 2018 to June 2018. This will allow trains to run seamlessly on the new CBTC system across the entire EWL, including the TWE. Shorter train service hours are expected monthly at different sectors of the EWL for the first half of the year accelerate the completion of the CBTC system.

From the various issues faced on the NSL, we could take all these into learning points and implement the EWL CBTC with a smoother transition and fewer hiccups along the way. On the first few weeks of revenue service CBTC testing, there should be parallel bus services deployed along the EWL corridor to alleviate the situation should train services stalls or degrade.

This happened quite often during the first week of weekday testing on the NSL affecting passengers who needed the MRT for their commute to work or school. Also, fares along the EWL could be waived should there be delays of above 15 minutes.

Whenever major train incidents occur, SMRT staffs bear the full brunt of commuters’ frustrations. In addition, many off-duty SMRT staff are obliged to respond to the call of duty immediately upon activation, providing assistance to queries and guiding passengers to alternative transportation – all these amidst waves of unhappiness from commuters. Frustration is not only felt by passengers, but also the staff as well. We would sincerely like to applaud and appreciate all the SMRT staff for their commitment and patience through these episodes.

In all, better planning from the authorities could have prevented these incidents, and if the authorities had not pushed for such a tight deadline to commission the CBTC system, it would have allowed the signalling contractor Thales to continue testing on the NSL for a longer period of time. The result could have been a CBTC roll-out that is much better, with less teething issues as compared to those experienced by the NSL currently.


You Yuan

President of SGTrains since 2011. Studying Bachelor in Business Information System at University of Wollongong, Australia.