LTA, rail operators to investigate root causes of three unrelated MRT disruptions in a week

The Land Transport Authority (LTA) and rail operators SMRT and SBS Transit are working closely to identify the root causes of three MRT disruptions in the past week.

LTA said in a statement on Thursday (Feb 13) that it takes a serious view of the recent incidents and that the three disruptions on Feb 7, Feb 10, and Feb 11 were unrelated.

North-South Line disruption on Feb 7 caused by derailment of stalled engineering vehicle at Bishan Depot

“North-South Line – Please expect longer waiting time of up to 5 minutes on North-South, East-West lines (NSEWL) train service due to an engineering vehicle fault. Free regular bus and bridging bus services are available between Bishan and Woodlands stations. Passengers are advised to use Thomson-East Coast Line (TEL) and Circle Line (CCL).” (Image: Screengrab from SGTrains)

In the early morning, at around 5:15am on Feb 7, an engineering vehicle broke down at a track crossing in Bishan Depot after completing routine maintenance works. This prevented MRT trains in Bishan Depot from being deployed into passenger service.

During SMRT’s attempt to move the stalled engineering vehicle using a rescue train, the engineering vehicle derailed; some of its wheels came off the running rails.

As trains from Bishan Depot primarily serve the North-South Line (NSL), the rail operator had to redirect some trains from the East-West Line (EWL) to the NSL to ensure that the NSL could commence operations.

“North-South, East-West lines – Please expect longer intervals between trains of about 3.5 minutes on North-South, East-West lines (NSEWL) during this evening’s peak hours. Commuters are advised to take alternative lines or other modes of transport to continue their journey.” (Image: Screengrab from SGTrains)

SGTrains understands that the other MRT depots which serve the North-South, East-West lines (NSEWL) include Tuas Depot, Ulu Pandan Depot, and Changi Depot.

The redirection of trains from the EWL to the NSL allowed train services to operate throughout the day on both lines, albeit with a longer interval between trains during peak hours, due to the lack of overall running trains.

Free regular and free bridging bus services were provided between Woodlands and Bishan stations to augment train capacity during the morning peak hours.

The stalled engineering vehicle was cleared by 5:30pm the same day, enabling SMRT to launch trains from Bishan Depot and progressively restore normal service for the evening peak.

“LTA and SMRT are conducting a thorough investigation into the root cause of this incident.”

North East Line disruption on Feb 10 caused by a fault in the signalling system near Buangkok station

“North East Line – Due to a signalling fault, please add an additional travelling time of 15 minutes.” (Image: Screengrab from SGTrains)

Just before the morning peak hours at 6:08am on Feb 10, a signalling system fault near Buangkok station caused trains on the North East Line (NEL) to travel slower.

Rail operator SBS Transit provided free regular and free bridging bus services between Punggol Coast and Dhoby Ghaut stations. Normal train services resumed nearly two hours after the disruption started at around 8:00am.

“Preliminary investigations indicate that the incident was due to a fault in the signalling equipment, caused by a malfunctioning electronic card,” said LTA.

It added that SBS Transit replaced the malfunctioning electronic card on the same morning and restored the system’s operations. The malfunctioning component has been sent to Alstom, the signalling system’s manufacturer, for further examination.

Circle Line disruption on Feb 11 caused by a fault in the signalling system, leading to a power trip, and a sluggish Central ATS system during resumption

“Circle Line – Delays reported along Circle Line. Crowding observed at interchange stations.” (Image: Screengrab from SGTrains)

During the height of the morning peak hours at 8:15am on Feb 11, a signalling system fault occurred between Paya Lebar and Marymount stations on the Circle Line (CCL).

The signalling system fault caused a “power trip”, which stalled 17 trains. Power was subsequently restored, and train movement progressively resumed at 8:20am.

However, while restoring operations, SMRT observed that the Central Automatic Train Supervision (CATS) system, which regulates the movement of driverless trains, was less responsive than usual, causing a delay in the resumption of normal operations.

LTA said: “We last experienced this issue on the CATS system in September 2024. LTA and SMRT have been working with Alstom, who is the system manufacturer, over the past few months to develop a software patch.”

The software patch was scheduled to be deployed during the weekend of Feb 15-16, following the completion of rigorous testing.

SGTrains noted that as we did not receive any train disruption alert from an LTA data feed, we were, however, alerted via crowdsourced information on the disruption, which we then proactively displayed on our Train Service Status web page.

In a news article published by The Straits Times, it said: “But it was only two hours later, just after 10.20am, that SMRT made its first social media post acknowledging the issue.”

SGTrains also understands that the NEL and CCL use Alstom’s ‘Urbalis 300’ Communications-Based Train Control (CBTC) signalling system, first commissioned in 2003 and 2009, respectively.

Unlike the NSEWL, which underwent a resignalling project in 2017-18 to replace its legacy fixed-block signalling system commissioned in 1987 when the line opened, the NEL and CCL continue to use their original signalling system since their respective openings.

Related Links
Train Service Status – SGTrains
North-South Line – SGTrains
East-West Line – SGTrains
North East Line – SGTrains
Circle Line – SGTrains

External Links
“Rail safety and reliability are key priorities” – LTA/Facebook

Images: SMRT/Facebook, Screengrabs from Train Service Status – SGTrains.
This article first appeared on SGTrains.