East-West Line probe shows no detail is too minute in rail maintenance

Even the smallest early warning signs of trouble should not be ignored

- Kenneth Cheng

The outcome of a months-long investigation into one of Singapore's worst MRT breakdowns is a stark and vital reminder that no single part of the rail system — even something as basic as grease — can be ignored.

Degraded grease on a faulty part of a train's undercarriage was pinpointed as the likely cause of a chain of events that downed MRT services along a stretch of the East-West Line for six days in September 2024.

Several points raised by investigators in reports released on June 3 highlight the need for rail operator SMRT to tighten its procedures and take early signs of a fault seriously. They also point to the importance of greater regulatory oversight of maintenance procedures.

First, while it was commendable of SMRT to install a tool on its own initiative to detect overheating in an undercarriage component called an axle box, the system did not work as intended.

On Sept 25, 2024, the tool detected a temperature of 118 deg C on the faulty axle box — an early sign of overheating — but the system could not identify which train it was on.

As a result, a staff member believed the notification to be a false warning and did not follow up.

This was a missed opportunity for SMRT to nip the problem in the bud, given that the temperature reading came almost two hours before the axle box dislodged from the train. An axle box holds the train's wheels to the axle, a rod connecting a pair of wheels.

Had the tool worked and the operator's protocol been activated, the train would have been withdrawn immediately, potentially altering the course of events that fateful day.

The findings from an independent Transport Safety Investigation Bureau (TSIB) probe were also instructive.

It found that SMRT staff had told their supervisors about the system's inability to identify trains with axle boxes of higher temperatures, but the issue went unresolved.