ST Explains: What is a track point fault and why does it cause lengthy train disruptions?

SINGAPORE - A track point fault that occurred at about 6am on Aug 6 caused

delays to eastbound train services on the East-West Line (EWL)

between Boon Lay and Clementi, drawing ire from passengers travelling during the morning rush.

The issue occurred near Jurong East MRT station and took five hours to resolve.

Trains had to be driven at 18kmh – down from the usual speed of up to 80kmh – as SMRT engineers went on the tracks to fix the malfunction, resulting in additional travelling time of 25 minutes or more.

The Straits Times explains what a track point fault entails and why such faults can have a major impact on rail operations.

What is a track point fault?

A track point is a railway switch that allows trains to change tracks.

Track point faults are malfunctions of these switches, and they typically involve a key piece of trackside equipment called a point machine.

However, there have been occasions when an issue with a point machine was categorised as a “track fault”, which is a broader catch-all term that encompasses other track issues such as rail cracks.

For example, what was said to be a track fault on the North-South Line (NSL) on Feb 6, 2023, was later attributed to a piece of granite that got stuck on the underside of a point machine near Woodlands MRT station.

What is a point machine?

A point machine is a device weighing 90kg that is installed at rail junctions to control the movement of railway switches, ensuring they are correctly positioned.

These devices are usually controlled automatically by the MRT line’s signalling system, and they push and pull a piece of moveable rail that guides trains onto the right track.

This is so that, for instance, trains can move from the main MRT tracks to a set of side tracks leading to a train depot, and vice versa.

What can cause a point machine to fail?

A 2023 journal article by researchers from Beijing Jiaotong University and the operator of the Beijing subway noted that point machines naturally degrade due to operational wear and tear.

“Mechanical transmission components and electrical units in point machines inevitably fail. Furthermore, point machines work alongside railway lines, where the environment is... harsh,” the article said.

Singapore Institute of Technology associate professor Andrew Ng, who has done research on railway technologies, said a point machine can fail due to various reasons such as worn components and faulty electrical connections.

When this happens, trains cannot move in automatic mode and must be driven manually at significantly lower speeds for passenger safety, he added. During past track point faults here, trains have been driven as slowly as 5kmh.

Common parts that can fail include the drive mechanism that moves the railway switch, as well as the detector that ensures the switch is locked into position.

In 2018, a track point fault near Clementi MRT station that

lasted almost seven hours

was traced to a displaced point machine detector.

Another track point fault, which lasted six hours on Feb 8, 2023, was later traced to a faulty point detection cable, which had earlier been replaced as part of NSEWL (North-South and East-West lines) systems renewal.

How serious are track point faults and how long does it take to fix them?

Prof Ng said it is essential to fix track point faults to ensure that train operations can continue safely. The recovery time depends on what caused the failure and the components that need to be swopped.

It can take a few minutes if what is needed is a simple replacement of an easily accessible part, but it may take longer if the task is more complex, Prof Ng added.

Past faults have taken at least a couple of hours to resolve. This is because engineers need to access the track to diagnose the problem and fix it, which can be a safety concern when trains are still running, especially during peak periods.

Two SMRT workers died in 2016

while they were investigating a track point fault near Pasir Ris station, though this was because a number of personnel had failed to observe safety protocol that day.

Prof Ng said there are limited windows of about five to 10 minutes during passenger service hours for the maintenance team to identify and rectify the problem.

“If the team cannot complete the recovery within this time, they will return on another train for a follow-up,” he added.

In the case of the 2018 track point fault near Clementi station, SMRT engineers had to get onto the tracks six times to identify and work on the defect.

At first, train service between Clementi and Jurong East stations was halted for about 30 minutes, so the faulty point machine could be inspected. As the fault happened during the morning peak period, a decision was later made to let train service resume, albeit at slower speeds, and to work on the issue after the rush was over.

It was a similar story on Aug 6.

SMRT said in an update at 11.20am that its engineers went onto the track near Jurong East MRT station after the morning peak period to investigate and resolve the issue.

If left unfixed, a faulty point machine can lead to more serious incidents.

This was the case in Britain in 2002 when poor maintenance of a track point caused a train passing over it to derail, killing seven and injuring 76.

What else is being done about this?

In a Facebook post on Aug 6, Acting Transport Minister Jeffrey Siow said maintaining point machines is a laborious process, as it involves opening up the device, testing all the circuits and cleaning the gears by hand with a file.

SMRT has said that at least five people are needed to service and overhaul the machines during night hours because of their heft.

In recent years, rail operators SMRT and SBS Transit (SBST) have begun to roll out new systems that can monitor the health of point machines, so maintenance can be done before failures occur.

In August 2024, SMRT deployed an in-house monitoring system for point machines along the Circle Line. ST has asked the rail operator if the system has been extended to the NSEWL.

Meanwhile, 90 per cent of the point machines on the SBST-run North East Line will be equipped with a condition monitoring system by the end of August. Point machines with this system have also been installed at Bukit Panjang station on the Downtown Line (DTL).

In May 2024, SBST also inked a deal with German company Siemens Mobility to establish a local authorised maintenance centre for point machines that are used on the DTL and will be installed on the upcoming Jurong Region Line and Cross Island Line.

Under the agreement, Siemens Mobility will supply the essential spare parts. It will also train SBST engineers to maintain these specific devices.