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SMRT to be fined $3m for major East-West Line disruption in September 2024
Jun 03, 2025
SINGAPORE –Rail operator SMRT will be fined $3 million for a major six-day disruption on the East-West Line (EWL) in September 2024, said the Land Transport Authority (LTA) on June 3.
LTA said the penalty was “proportionate” to the circumstances of the incident, which crippled MRT services between Jurong East and Buona Vista stations and disrupted about one in six train trips daily.
The authority said it considered the cost SMRT had borne from repairs, as well as from providing free bus and shuttle train services at the affected stations.
Releasing the findings of its months-long investigation into the incident, LTA said degraded grease was likely to have caused a faulty part of a train’s undercarriage to fall out, which precipitated the disruption on the morning of Sept 25, 2024.
The part – called an axle box, which holds the train’s wheels to the axle, a rod connecting a pair of wheels – was dislodged near Dover station while the train was being withdrawn from service to Ulu Pandan Depot.
This caused one of the train’s 12 bogies – a structure below the train carriage – to derail.
The six-car train could continue travelling as the other 11 bogies remained on the rails. But the derailed portion of the third carriage caused extensive damage to 2.55km of track and trackside equipment, such as power cables and the third rail, which supplies power to trains.
LTA found that grease keeping the axle bearings lubricated within the axle box was likely to have been degraded. The bearings are mechanical parts that allow the smooth rotation of the wheels when the train is running.
Grease that has lost lubrication capabilities can cause increased wear and tear of the bearings and, eventually, overheating.
The axle box is held in place by chevron springs – metal plates bonded together by rubber that absorb vibrations when trains are operating.
LTA said its investigation findings suggest that the bearings had produced enough heat to ignite the rubber layers between the springs, causing them to disintegrate.
With the springs progressively falling off, the axle box was then dislodged.
The axle box and bearings were badly damaged, and the grease in the axle box had been completely burned off when these parts were later recovered. Debris from the chevron springs was also too badly damaged for tests to be done to determine any initial damage before the incident, said LTA.
“It was therefore not possible to establish a definitive root cause,” it said, adding that grease samples from other axle boxes of the affected train had also shown signs of degradation.
LTA said this sequence of events was substantiated by a monitoring tool that SMRT installed near Lavender station, which detected a temperature of 118 deg C on the affected axle box earlier that morning – higher than the typical operating temperature of up to 65 deg C.
A system error, however, meant that SMRT could not identify the train on which the axle box was mounted, leading to a staff member mistakenly believing the notification to be a false warning. There was no follow-up action.
In a separate probe into the incident, Singapore’s Transport Safety Investigation Bureau (TSIB) said it had considered two possible scenarios.
One, that the bearings had failed first due to heat and friction generated within the axle box because of the degradation of grease.
Two, that the rubber of the chevron springs had deteriorated to a point where it could no longer serve as the train’s primary suspension. This then put stress on the bearings, which eventually failed, generating heat and friction within the axle box.
However, TSIB, a department of the Ministry of Transport, said it could not determine which scenario was more likely to have occurred, owing to the severely damaged axle box and springs.
LTA, which commissioned SGS Testing and Control Services to do an independent forensic analysis, said the company found that degraded grease was a likely cause.
“While the weakened chevron spring could not be ruled out as a possible cause, the possibility was likely low,” LTA added, noting that the high temperature of the axle box detected near Lavender suggests that the bearings had failed first.
The train in question, which is no longer in use, is a Kawasaki Heavy Industries (KHI) train.
These first-generation trains are being progressively replaced by new trains, the delivery of which was delayed by 1½ years because of the Covid-19 pandemic.
The last maintenance checks on the affected train, on July 15 and Sept 10 in 2024, did not detect any anomalies.
LTA noted that SMRT had extended the interval between overhauls for the train beyond the requirement of doing so after every 500,000km travelled. The interval was extended to 575,000km in August 2022, and to 750,000km in August 2024.
At the time of the incident, the train had logged 690,000km since its last overhaul in July 2018.
During such overhauls, the axle box, bearings and chevron springs will be replaced where needed. Fresh grease will also be reapplied on the bearings.
Had the affected train been overhauled in a more timely way, the “condition of its axle box assemblies would have been checked and any degraded grease could have been replaced earlier”, LTA noted.
At the time of the incident, 18 out of 38 KHI trains that were set to undergo overhauls had been refurbished. These 18 trains had been chosen based on their reliability, mileage and condition, SMRT said.
While the authority was aware of SMRT’s procedures to vary its overhaul intervals, there was no requirement for SMRT to notify LTA when these were done.
“As axle box failures are not common, SMRT did not undertake a detailed engineering and risk assessment on extending the axle box overhaul interval,” said the regulator.
SMRT Trains president Lam Sheau Kai told reporters at a briefing that the operator’s overhaul regime has served it well over the last 38 years.
“What may have caught us off guard this time was the convergence of factors – delays in new train deliveries due to Covid-19, our efforts to balance and adjust overhaul schedules, and the lag in receiving critical spare parts,” he said.
The pandemic disrupted global supply chains, holding up new trains and the spare parts needed for the overhauls. It also affected SMRT’s ability to do additional overhauls after 2018, the operator said.
In black-swan events such as Covid-19, it is important that SMRT and LTA come together to reassess the circumstances collectively, Mr Lam added.
“In hindsight, we could perhaps have exercised greater caution in how we managed the transition and decommissioning of the older trains.”
LTA said it would provide “more time buffer” in future purchases of trains to mitigate against unforeseen supply chain disruptions.
There have been similar incidents of axle boxes getting dislodged in other rail systems, Mr Lam said, adding these are “extremely rare, sudden and catastrophic”.
“Even for those metros, such failures caught them off guard due to their acute nature.”
What triggered the six-day East-West Line MRT disruption in 2024
Interactive: How a faulty MRT train left a trail of destruction
What SMRT, LTA did after the incident
After the incident, SMRT withdrew all KHI trains with a mileage exceeding 500,000km to undergo overhauls of the axle boxes, before they were returned to service. This was completed in October 2024.All 16 KHI trains that are still in service will be phased out by September.
SMRT also began tapping data analytics to detect abnormal axle box temperatures earlier. It resolved the system error with its temperature-monitoring tool, and strengthened procedures for staff to raise alerts about high temperatures in a timely manner.
It has also lowered the speed of trains being withdrawn to depots under similar scenarios to 35kmh, to limit potential damage to the tracks and trackside equipment.
LTA said the affected train had been withdrawn to Ulu Pandan Depot at about 70kmh on automatic mode – which does not require driver input – in accordance with SMRT’s protocols, as its staff were not aware that doing so could exacerbate the damage.
SMRT said that during interviews for the investigation, the driver of the affected train said he did not observe irregularities or unusual occurrences as it was being withdrawn.
SMRT is also reviewing how it approves changes to maintenance regimes.
As the owner of rail assets, LTA has beefed up its oversight of how operators manage assets, including their procedures to adjust maintenance schedules.
The authority said it will work with operators for future overhaul decisions.
Operators remain responsible for their maintenance decisions, but have to flag changes to overhaul intervals for systems that are critical to safety, LTA added.
LTA said it is also engaging independent advisers to get advice on operations and maintenance strategies, as well as reliability improvements.
The major disruption – one of the worst to hit Singapore’s MRT system – affected about
500,000 out of 2.8 million train journeys
daily from Sept 25 to 30 in 2024.
It started after the train developed a fault at about 9am while travelling eastward near Clementi station.
A burning smell was detected from the faulty train, and SMRT stopped the train at Clementi station so passengers could alight, before it was withdrawn to Ulu Pandan Depot.
The train turned around at Queenstown station and was travelling westward between Dover and Clementi stations when the axle box came off.
Train services along the affected stretch resumed on Oct 1, 2024, after extensive repair and restoration works were completed on Sept 30.
