Investigation into Singapore MRT disruption must determine whether incident was preventable and help restore public trust

SINGAPORE: Train services along a four-station stretch of the East-West Line between Jurong East and Buona Vista will remain disrupted over the weekend, in an outage that has so far affected travel for more than 1.3 million passengers.

The disruption was caused by a faulty train returning to the Ulu Pandan depot on Wednesday (September 25).

A faulty axle box – a component of a train’s running gear – has fallen near Dover station. This caused the undercarriage, or bogie, to derail.

It left significant damage to tracks and trackside equipment in its wake.

How did the axle box become dislodged from the bogie and was the incident preventable, given the widespread use of preventative technologies in railway maintenance?

These are among the questions that must be answered by the investigation into this serious incident.

Preventative maintenance has been a priority for SMRT.

About nine years ago, for example, the rail operator adopted a monitoring system that deploys sensors to scan the entire rail fleet on the North-South and East-West lines for defects on wheels and train axles.

Axles connect the wheels of a train.

Although it is unclear whether such a system could have detected a faulty axle box, the fact is that SMRT has used the technology to strengthen rail maintenance and better predict when parts will fail and need to be replaced .

The North-South and East-West lines have also just undergone a S$2.6 billion renewal program for its six main systems.

These include replacing the sleepers that hold the running rail in place, changing the third rail that powers the trains, modernizing the signaling system and renewing the electrical power system.

The replacement of older trains is also part of the renewal program and will be rolled out gradually until the end of 2026.

The faulty train in question was a first-generation workhorse of Kawasaki Heavy Industries for more than 35 years, and there are 48 others still in service.

This is the first time a faulty axle box has come loose from an SMRT train, and such occurrences are rare.

Associate Professor Yap Fook Fah, co-director of the Transportation Research Center at Nanyang Technological University, said it was very unusual for axle box failures to occur.

Train parts, such as axle boxes, are “over-engineered” and are built to last as they have passed rigorous testing to adhere to international standards, he added.

“This is because the axle boxes are designed to be very sturdy, so it is difficult to understand why they fell,” said Professor Yap, who is also a member of the railway and transport engineering technical committee from the Institution of Engineers, Singapore. .

Mahesh Hariharan, deputy director of the railway, transportation and logistics department at the Technical University of Munich in Asia, said one of the reasons could be wear of axle box bearings that have been exposed to harsh conditions on the tracks.

This could be due to repeated vibrations of the rail from the wheels coming into contact with the rail, he added, or to defects along the rail or on the wheels.

Another question is why the train continued to run on the westbound track towards Ulu Pandan depot despite the bogie derailing, causing serious damage to the track and equipment.

It is still unclear when on September 25 part of the wagon derailed and what prompted the train driver to stop it on the track leading to the depot.

What we do know is that the faulty axle box was on the third car of the six-car train.

Professor Yap said the train driver, located in the first carriage, could have been “quite far away” and might not have immediately noticed anything was wrong. Each car is approximately 22 m long.

Hariharan noted that older SMRT trains may also not be equipped with the same advanced condition monitoring systems found on newer trains.

These systems collect data from onboard sensors so that preventative maintenance can be performed before failures occur.

Older trains therefore “lack extra eyes” to detect defects, he added.

Whether sufficient checks were carried out on the defective part before the incident is another question the investigation should look into.

For now, Prof Yap suggested carrying out more checks – beyond the stipulated inspection frequency – to gather up-to-date information on the condition of trains, especially older ones.

Hariharan agreed that special attention could be given to older trains, with more frequent checks and stricter inspections for those in service longer.

Train axle boxes are inspected every three weeks as part of SMRT’s current maintenance regime.

The operator will discuss with the Land Transport Authority whether the frequency of inspections should be increased.

As well as shedding light on what went wrong, a thorough investigation will help train operators and authorities take steps to learn from this disruption and better manage the consequences of future incidents.

Given the major disruption that is inconveniencing so many, a full accounting of the incident will also go some way to restoring public confidence.

Affected commuters deserve no less. -The time of the straits/ANN