SINGAPORE: Investigation findings for the six-day East-West Line disruption in September last year were released on Tuesday (Jun 3), with the Land Transport Authority (LTA) set to impose a S$3 million fine on train operator SMRT.
CNA breaks down the key points of the reports released by the Transport Safety Investigation Bureau as well as LTA.
Disruptions started on Sep 25 last year when a defective part known as an axle box on a first-generation KHI train dropped onto the tracks, causing a bogie – or an undercarriage with wheels – to come off the running rail between the Dover and Clementi stations.
This resulted in extensive damage to the tracks and other equipment, with a total of 46 rail breaks identified in a 2.55km stretch between Dover station and stretching beyond Clementi station, which took days to repair.
An estimated 500,000 out of 2.8 million train journeys were affected each day during the disruption, with train services resuming six days later on Oct 1.
An SBS Transit staff member holding an umbrella to shield commuters from the rain (left), while a long queue for bridging buses formed outside Buona Vista MRT station (right) after a train service disruption. (Photos: CNA/Wallace Woon)
SMRT activated free public bus and bridging shuttle bus services immediately when they understood that the train services would take some time to resume.
They also took action to limit the affected sector between Buona Vista station and Jurong East station.
Shuttle train services with 10-minute intervals operated between Boon Lay and Jurong East stations, as well as between Buona Vista and Queenstown stations.
Station staff members and track repair workers were also reported to have gone above and beyond their call of duty – from providing commuters with directions and assistance to coordinating track repairs round the clock.
The root cause of how the axle box failed could not be determined because key train components involved were too badly burnt and damaged in the incident, LTA said.
These parts were:
The axle box had dislodged from the third carriage of the train, causing extensive damage to the tracks.
Although the root cause could not be determined, the report concluded that the likely cause was degraded grease in the axle box, LTA said.
The degraded grease could have increased wear and tear on the axle bearings, eventually causing overheating, potentially burning the rubber of the chevron springs.
The chevron springs could have then progressively dropped off and eventually caused the axle box to dislodge, LTA added.
The sequence of events was further substantiated by the Hotbox system, which is set up along the tracks on both the East-West Line and North-South Line.
The system has been in place since 2014 and consists of a trackside infrared sensor. When a train runs by, the sensor measures the temperature of each axle box.
It is an extra monitoring tool put in place by SMRT and not a requirement set by LTA. The system had detected higher temperatures on one of the axle boxes of the affected train before the incident.
However, on the incident day, even though a warning was displayed in the maintenance engineering centre, the train identification number or train ID was not detected due to a system error. Instead, a “Null ID” was indicated.
This led the controller monitoring the system to believe the warning was a false one and no follow-up action was taken.
The axle box and chevron springs recovered from an MRT train. The dislodged components damaged the rail, leading to a disruption of train services. (Image: Transport Safety Investigation Bureau)
The missing axle box and chevron springs of the train that caused extensive damage to 2.55km of track and trackside equipment. (Image: Transport Safety Investigation Bureau)
The train in the incident was among 66 in SMRT's first-generation KHI fleet that were rolled out in the late 1980s. They are progressively being replaced by new Movia trains.
Initially, 66 Movia trains were to be handed over to SMRT by March 2024, with the first fleet in October 2021.
Due to the COVID-19 pandemic, there was a delay of 1.5 years and the first Movia train was handed over only in May 2023.
Upon receiving the first fleet of the new trains, SMRT began decommissioning the KHI trains.
In the meantime, SMRT was required to continue carrying out regular maintenance for the KHI trains still in service, including preventive works and overhaul, which refers to a complete tear-down and rebuild to restore trains to a condition "as good as new".
By the time of the incident on Sep 25, 18 KHI trains had been overhauled, but the incident train was not among them.
The stipulated interval for an overhaul was 500,000km, but SMRT twice extended the interval – first to 575,000km in August 2022 and then to 750,000km in August 2024.
At the time of the incident, the train had logged 690,000km since its last overhaul in 2018.
The extensions were carried out based on SMRT’s internal procedures, LTA said.
The authority also noted that since axle-box failures were not common, SMRT did not undertake a detailed engineering risk assessment on extending the overhaul interval for the axle box.
Speaking to the media on Tuesday, Mr Lam Sheau Kai who is president of SMRT Trains said the operator's overhaul regime has served it well over the past 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.”
SMRT was fined S$3 million by LTA, an amount that was “proportionate" to the incident’s circumstances, the authority said.
In determining the fine, LTA said it took into consideration that SMRT had borne the cost of repairs as well as provided free bridging buses, regular bus services and shuttle train services at the affected stations.
SMRT also provided free travel to passengers alighting at Jurong East and Buona Vista stations during the six days of disruption.
The total cost of SMRT’s service recovery amounted to more than S$10 million.
The financial penalty collected by LTA will go to the Public Transport Fund, which helps lower-income families with the spending on public transport fares.
SMRT will have the opportunity to appeal the fine to the transport minister.
After the incident, SMRT pre-emptively withdrew all KHI trains that had exceeded 500,000km mileage since their last overhaul from service to undergo overhaul activities for axle boxes before they were put back into service.
In consultation with LTA, SMRT has also starting using data analytics for earlier detection of abnormal axle-box temperatures, so that pre-emptive action can be taken.
SMRT has also worked with the Hotbox system maker to rectify the Null ID indication issue.
It now requires its maintenance engineering centre to share system warnings with the operations control centre.
SMRT has also instituted that the withdrawal of trains back to the depot under such scenarios should occur at a slower speed of 35kmh to limit the potential damage to the tracks and trackside equipment.
LTA was not involved in and did not review SMRT’s proposed extensions to the overhaul intervals of the trains.
The authority said that as an asset owner, it has since strengthened its oversight of operators’ management of assets, including their internal procedures to adjust maintenance schedules.
“LTA and operators will work together for future overhaul decisions,” it added.
Mr Lam from SMRT said that for “rare, black swan events like COVID-19”, it is important that SMRT the operator and LTA the asset owner come together to “reassess collectively”.
“In hindsight, we could perhaps have exercised greater caution in how we managed the transition and decommissioning of the older trains,” he added.
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CNA breaks down the key points of the reports released by the Transport Safety Investigation Bureau as well as LTA.
What happened in September?
Disruptions started on Sep 25 last year when a defective part known as an axle box on a first-generation KHI train dropped onto the tracks, causing a bogie – or an undercarriage with wheels – to come off the running rail between the Dover and Clementi stations.
This resulted in extensive damage to the tracks and other equipment, with a total of 46 rail breaks identified in a 2.55km stretch between Dover station and stretching beyond Clementi station, which took days to repair.
An estimated 500,000 out of 2.8 million train journeys were affected each day during the disruption, with train services resuming six days later on Oct 1.
An SBS Transit staff member holding an umbrella to shield commuters from the rain (left), while a long queue for bridging buses formed outside Buona Vista MRT station (right) after a train service disruption. (Photos: CNA/Wallace Woon)
How did SMRT respond then?
SMRT activated free public bus and bridging shuttle bus services immediately when they understood that the train services would take some time to resume.
They also took action to limit the affected sector between Buona Vista station and Jurong East station.
Shuttle train services with 10-minute intervals operated between Boon Lay and Jurong East stations, as well as between Buona Vista and Queenstown stations.
Station staff members and track repair workers were also reported to have gone above and beyond their call of duty – from providing commuters with directions and assistance to coordinating track repairs round the clock.
Related:
What did further investigations find?
The root cause of how the axle box failed could not be determined because key train components involved were too badly burnt and damaged in the incident, LTA said.
These parts were:
- the axle box itself, which secures the wheels to the axle
- the axle bearings, which reduce friction so the wheels spin smoothly
- the chevron springs, which contain rubber to absorb shocks to keep the ride smooth
The axle box had dislodged from the third carriage of the train, causing extensive damage to the tracks.
Although the root cause could not be determined, the report concluded that the likely cause was degraded grease in the axle box, LTA said.
The degraded grease could have increased wear and tear on the axle bearings, eventually causing overheating, potentially burning the rubber of the chevron springs.
The chevron springs could have then progressively dropped off and eventually caused the axle box to dislodge, LTA added.
The sequence of events was further substantiated by the Hotbox system, which is set up along the tracks on both the East-West Line and North-South Line.
The system has been in place since 2014 and consists of a trackside infrared sensor. When a train runs by, the sensor measures the temperature of each axle box.
It is an extra monitoring tool put in place by SMRT and not a requirement set by LTA. The system had detected higher temperatures on one of the axle boxes of the affected train before the incident.
However, on the incident day, even though a warning was displayed in the maintenance engineering centre, the train identification number or train ID was not detected due to a system error. Instead, a “Null ID” was indicated.
This led the controller monitoring the system to believe the warning was a false one and no follow-up action was taken.
The axle box and chevron springs recovered from an MRT train. The dislodged components damaged the rail, leading to a disruption of train services. (Image: Transport Safety Investigation Bureau)
The missing axle box and chevron springs of the train that caused extensive damage to 2.55km of track and trackside equipment. (Image: Transport Safety Investigation Bureau)
How much of a factor was maintenance?
The train in the incident was among 66 in SMRT's first-generation KHI fleet that were rolled out in the late 1980s. They are progressively being replaced by new Movia trains.
Initially, 66 Movia trains were to be handed over to SMRT by March 2024, with the first fleet in October 2021.
Due to the COVID-19 pandemic, there was a delay of 1.5 years and the first Movia train was handed over only in May 2023.
Upon receiving the first fleet of the new trains, SMRT began decommissioning the KHI trains.
In the meantime, SMRT was required to continue carrying out regular maintenance for the KHI trains still in service, including preventive works and overhaul, which refers to a complete tear-down and rebuild to restore trains to a condition "as good as new".
By the time of the incident on Sep 25, 18 KHI trains had been overhauled, but the incident train was not among them.
The stipulated interval for an overhaul was 500,000km, but SMRT twice extended the interval – first to 575,000km in August 2022 and then to 750,000km in August 2024.
At the time of the incident, the train had logged 690,000km since its last overhaul in 2018.
The extensions were carried out based on SMRT’s internal procedures, LTA said.
The authority also noted that since axle-box failures were not common, SMRT did not undertake a detailed engineering risk assessment on extending the overhaul interval for the axle box.
Speaking to the media on Tuesday, Mr Lam Sheau Kai who is president of SMRT Trains said the operator's overhaul regime has served it well over the past 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.”
What penalties were imposed?
SMRT was fined S$3 million by LTA, an amount that was “proportionate" to the incident’s circumstances, the authority said.
In determining the fine, LTA said it took into consideration that SMRT had borne the cost of repairs as well as provided free bridging buses, regular bus services and shuttle train services at the affected stations.
SMRT also provided free travel to passengers alighting at Jurong East and Buona Vista stations during the six days of disruption.
The total cost of SMRT’s service recovery amounted to more than S$10 million.
The financial penalty collected by LTA will go to the Public Transport Fund, which helps lower-income families with the spending on public transport fares.
SMRT will have the opportunity to appeal the fine to the transport minister.
Related:
What follow-up actions have SMRT and LTA taken since then?
After the incident, SMRT pre-emptively withdrew all KHI trains that had exceeded 500,000km mileage since their last overhaul from service to undergo overhaul activities for axle boxes before they were put back into service.
In consultation with LTA, SMRT has also starting using data analytics for earlier detection of abnormal axle-box temperatures, so that pre-emptive action can be taken.
SMRT has also worked with the Hotbox system maker to rectify the Null ID indication issue.
It now requires its maintenance engineering centre to share system warnings with the operations control centre.
SMRT has also instituted that the withdrawal of trains back to the depot under such scenarios should occur at a slower speed of 35kmh to limit the potential damage to the tracks and trackside equipment.
LTA was not involved in and did not review SMRT’s proposed extensions to the overhaul intervals of the trains.
The authority said that as an asset owner, it has since strengthened its oversight of operators’ management of assets, including their internal procedures to adjust maintenance schedules.
“LTA and operators will work together for future overhaul decisions,” it added.
Mr Lam from SMRT said that for “rare, black swan events like COVID-19”, it is important that SMRT the operator and LTA the asset owner come together to “reassess collectively”.
“In hindsight, we could perhaps have exercised greater caution in how we managed the transition and decommissioning of the older trains,” he added.
Continue reading...