Commuters on board a stalled train during the East-West Line disruption near Clementi station disembarked on the tracks and were guided back to the station platform. (Images: SGTrains)
Rail operator SMRT will be fined $3 million for lapses that caused the major six-day East-West Line (EWL) train service disruption in September 2024, the Land Transport Authority (LTA) said in a report released on Jun 3, following the completion of its investigation.
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In its report, LTA said the likely cause of the failure was degraded grease in the axle box, which can increase wear and tear on the axle bearings, eventually causing overheating and failure.
Diagram of an axle box (left) and its chevron springs (right). (Image: TSIB)
It added that recovered axle box components, including the chevron spring, were also badly damaged, and the axle box grease had also completely burned off, preventing further testing to identify any initial damage prior to the incident.
Thus, LTA said: “It was therefore not possible to establish a definitive root cause.”
Incident Background
Axle box of the second axle was missing. (Image: TSIB)
On Sep 25, 2024, Trainset 065/066, a 1st-gen Kawasaki Heavy Industries C151 train running on the North-South, East-West lines (NSEWL), registered high axle box temperature readings of 118 degrees Celsius as it passed by westbound at Lavender (EW11) station.
In response to reports of smoke and a burning smell from Trainset 065/066, the Operations Control Centre (OCC) instructed the train to be withdrawn to Ulu Pandan Depot (UPD). When Trainset 065/066 was entering UPD, it came to a stop on the depot’s reception track.
KHI C151 train bogie structure overview. (Image: LTA)
Four wheels on the front bogie of Car 2065 from Trainset 065/066 had derailed and come off the running rails. The axle box of Car 2065 was missing and was later recovered near Dover (EW22) station.
The running rails and trackside equipment along a stretch of 2,550m were severely damaged, a total of 46 rail cracks were formed, leading to the train service disruption. Normal train services on the EWL only resumed six days later on Oct 1, 2024.
The incident of Trainset 065/066 involving the fallen axle box, due to degraded grease that caused overheating and failure
LTA concluded that the likely cause of failure was degraded grease in the axle box, eventually causing overheating and failure, as supported by the presence of burned rubber and metal pieces from the chevron springs found along the path of Trainset 065/066.
“This suggested that the axle box had generated sufficient heat to burn the rubber of the chevron springs. The chevron springs then progressively dropped off and eventually caused the axle box to dislodge,” said LTA.
The Hotbox system failed to identify Trainset 065/066 and indicated a Null ID with a Level 1 warning, for an axle box temperature exceeding 90 degrees Celsius, at the Maintenance Engineering Centre. (Image: TSIB)
The overheating was further substantiated by the Hot Axle Box Detection (Hotbox) system, which had detected high temperatures on one axle box of Trainset 065/066 before the incident occurred.
The Hotbox system is an additional monitoring tool initiated by SMRT to detect high temperatures and alert maintenance staff to potential axle box-related issues.
However, the Transport Safety Investigation Bureau (TSIB), a department under the Ministry of Transport (MOT), also released a report on Jun 3, mentioning that the Hotbox system could not identify Trainset 065/066 and “generated a label of Null identity (ID) for the train”.
TSIB said the controller who was monitoring the Hotbox system noticed an indication of a Level 1 warning icon with the Null ID, and “believed it to be a false warning and took no follow-up action”.
“The training received by controllers did not address or provide guidance on actions to take when they encountered Null ID indications.
“The TSIB investigation team noted that there were instances of Null ID indications (i.e. train ID was not detected by the Hotbox system) as well as feedback from staff to the rail operator.
“However, the issue had not been resolved as Null ID indications were still being generated during operations,” said TSIB.
Locations where the debris pieces were found. (Image: TSIB)
When Trainset 065/066 turned around to go eastbound from Tuas Link (EW33) station, TSIB said some staff reported to OCC of a burning smell. OCC instructed the station manager (SM) of Tuas Link to check the westbound tracks, who later reported “there was no burning smell”.
As instructed by OCC to conduct an inspection, the SM of Clementi reported back that there was a burning smell inside Trainset 065/066 when it arrived at Clementi (EW23) station. OCC then ordered a detrainment, and for the train to be withdrawn.
Trainset 065/066 had to travel eastwards for four stations until the nearest turnaround point near Queenstown (EW19) station. OCC instructed the SM of Dover (EW22) station to check for any burning smell and smoke inside the train when it arrived at Dover station.
SM of Dover station reported to OCC that he noticed a burning smell inside Trainset 065/066 but did not notice any smoke on board. The train captain (TC) of the 1st-gen C151 train also did not notice any fault indications in his driving cab.
The SM of Dover station remained on Trainset 065/066 as it crossed over and turned around at Queenstown crossings. The traction power was tripped westbound between Dover and Clementi stations, but the train could coast without propulsion power into Clementi station.
OCC restored traction power and Trainset 065/066 then continued to UPD, while the SM of Dover station alighted at Clementi station. The traction power was again tripped, and the train stalled at the entrance of the UPD reception track.
This time, OCC could not restore traction power as Trainset 065/066 derailed at the UPD reception track, after causing severe damage to the running rails and trackside equipment.
SMRT extended the overhaul interval for Trainset 065/066 beyond its stipulated maintenance requirement twice
LTA said Trainset 065/066 was part of the 66-train 1st-gen C151 fleet, which is progressively being replaced by the 7th-gen Alstom Movia R151 trains.
Sixty-six (66) 7th-gen R151 trains were initially to be handed over to SMRT by March 2024, with the first trains to be handed over in October 2021.
However, LTA said that due to the pandemic, “there was a delay of 1.5 years” and the first R151 train was only handed over to SMRT in May 2023. It entered passenger service the following month on the EWL on Jun 4, 2023.
LTA said SMRT began decommissioning the C151 trains upon receiving the first R151 trains. It was still required to continue regular maintenance for the C151 trains still in passenger service, including preventive maintenance and overhaul.
The axle box assemblies on Trainset 065/066 had regular preventive maintenance carried out by SMRT, including one on Sep 10, 2024, just over two weeks before the incident, with “no anomalies found”.
LTA said: “SMRT had twice extended the overhaul interval for the incident train beyond its stipulated maintenance requirement of 500,000km, to 575,000km in August 2022, and to 750,000 km in August 2024.”
Trainset 065/066 was last overhauled in 2018 and had logged 690,000km since its last overhaul, around six years earlier.
The extensions of the overhaul intervals were carried out “based on SMRT’s internal procedures”. SMRT relied on analysis of the performance of the C151 train fleet and its “continued reliability” in deciding on the extensions for the incident train.
Since “axle box failures are not common”, SMRT did not undertake a detailed engineering and risk assessment on extending the axle box overhaul interval, LTA said.
In December 2023, SMRT started a “cycle of modular overhaul” for 38 C151 trains, including the incident train, still in passenger service and requiring overhaul of their safety-critical components.
A total of 18 1st-gen C151 trains had been overhauled by the time of the incident on Sep 25, 2024, with Trainset 065/066, the incident train, having not.
LTA said: “Had the incident train been overhauled in a more timely manner, the condition of its axle box assemblies would have been checked and any degraded grease could have been replaced earlier.”
Financial penalty of a $3 million fine on SMRT
The $3 million fine considers that SMRT bore the cost of repairs as rail assets are owned by LTA, and provision of free bridging and regular bus services across various bus operators, as well as shuttle train services at affected MRT stations.
“It also provided free travel to passengers alighting at Jurong East and Buona Vista stations for the six days of disruption. The total costs amounted to over $10 million.”
The financial penalty collected by LTA will go to the Public Transport Fund to help lower-income families with their public transport expenditures.
Subsequent actions following the incident
Following the incident, SMRT pre-emptively withdrew all C151 trains that had exceeded 500,000km mileage since their last overhaul from service in October 2024. They will undergo overhaul activities for axle boxes before re-entering passenger service.
Not mentioned in the report, SGTrains observed that following the incident, SMRT have also pre-emptively withdrawn the 2nd-gen Siemens C651 trains and the 3rd-gen Kawasaki-Nippon Sharyo C751B trains. These trains were fully decommissioned by December 2024.
READ MORE: Singapore’s 2nd-gen Siemens C651 have retired on Nov 27, 2024; first entered passenger service in 1995 »
READ MORE: Singapore’s 3rd-gen C751B trains have retired on Dec 7, 2024; first entered passenger service in 2000 »
LTA also developed an accelerated delivery programme for the new R151 trains, with the support of additional resources from SMRT and various contractors, to mitigate the delays from the pandemic.
This will allow all C151 trains to be decommissioned by the third quarter of this year. There are currently 33 C151 trains remaining, including 16 on regular passenger service. Rail operator SMRT earlier intended to fully retire all C151 trains by the third quarter of 2025.
SGTrains understands that 66 R151 trains have been delivered in Singapore, with 58 in passenger service, one on dynamic mainline testing, and the remaining in the depot for various testing and commissioning activities.
MORE INFO: Delivery of Alstom Movia R151 »
MORE INFO: Running Status of NSEWL Trains »
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Related Links
Train Service Status – SGTrains
Kawasaki Heavy Industries C151 – SGTrains
East-West Line – SGTrains
Running Status of NSEWL Trains – Spotters by SGTrains
Trainset 065/066 – Spotters by SGTrains
External Links
LTA Completes Investigation into the Cause of East-West Line Service Disruption in September 2024 – LTA
Final Report: East-West Line Faulty Train Incident – TSIB/MOT
Images: SGTrains, TSIB, LTA.
This article first appeared on SGTrains.
Last updated on 04 Jun 2025.