The report of the subway derailment accident on the east-west line in Singapore has been released

The Rail Transit Exhibition learned that the Ministry of Transport of Singapore has been involved in the derailment accident of the East-West Line subway in September last year, and the investigation shows that the possible reason for the large-scale interruption of some services of the East-West Line in September last year is the deterioration and degradation of the lubricating oil of the subway axle box, which wears the bearings (axle bearings), causing the parts to overheat and thus fail. On the day of the accident, the detection system had measured the temperature of the axle box of the train concerned as high as 118 degrees Celsius. However, due to a malfunction in the alarm system, it was not possible to identify which train was experiencing the high temperature, resulting in the operator not being able to take timely countermeasures.

The Traffic Safety Investigation Bureau under the Ministry of Transport released an investigation report on Tuesday (June 3), detailing the results of the investigation into the train derailment incident on the east-west line of the subway on September 25 last year.

According to the report, the Kawasaki Heavy Industries train T310 departed from Pasir Ris Station that morning and passed through Lavender Station when the axle box heat detection system detected an abnormally high temperature and triggered a Level 1 alarm at the engineering maintenance center console.

However, the system only showed "no number", that is, the train number was not determined, so the dispatcher on duty misjudged it as a false alarm by the system, and the train continued to run as usual without further notification or inspection.

At 8:22 a.m., the train arrived at Tuas Link Station and turned back to eastbound at 8:25 a.m. About five minutes later, the officers on duty reported to the control center for the first time that there was a burning smell in the compartment. The CFS immediately instructed a number of station masters to board the train at Clementi Station and Dufer Station for inspection; They confirmed a burnt smell, but no smoke was seen. At 8:53 a.m., the centre decided to withdraw the train to the Ulu Pandan Depot for maintenance.

Unexpectedly, after the train turned to the westbound line through the Queenstown Interchange, the traction power was interrupted twice between Clementi Station and Duver Station. At 9:20 a.m., the train lost power again when it entered the depot entrance track and stopped on the track.

The inspection found that the four front wheels of the middle car had been derailed, the axle box of the second axle had also fallen off, and part of the wreckage was scattered near the Duver station. The accident caused damage to about 2.5 kilometres of tracks, switches, cables and power rails.

The total number of trains traveled is 690,000 kilometers, far exceeding the 500,000 kilometers maintenance interval

The investigation found that since the last complete overhaul in 2018, the train has traveled a total of 690,000 kilometers, far exceeding the original maintenance interval of 500,000 kilometers.

According to the operator's regulations, trains must be inspected every 500,000 kilometers traveled, but there is a mechanism for postponing inspections, that is, if the mileage is extended by 10% (to 550,000 kilometers), no technical assessment is required; Extensions of 15% (to 575,000 km) or more require assessment and approval from the top management. Although the operator claimed to have assessed the reliability and condition of the train at the time, it was unable to provide a record of these extension requests, assessments and approvals.

While the lack of records of maintenance decisions does not necessarily lead directly to incidents, the report highlights that ensuring that every decision and assessment made by an organization in its day-to-day operations is well-documented and integral to ensuring the safety of the system.

The report also pointed out that there was a discrepancy between the operator's actual maintenance work and the train manufacturer's advice. For example, the manufacturer recommends semi-annual clearance checks for V-springs, while the operator increases the frequency to once every three weeks. Lubricating oil leak checks are recommended by the manufacturer on a weekly basis and every three months, and once every three weeks and every six months.

In terms of axle box inspections, although the manufacturer did not require a visual inspection every three weeks, the operator took the initiative to do so. However, the manufacturer recommended that a detailed inspection should be carried out every three months, but the operator extended it to once every six months.

As for overhauls, the manufacturer recommends overhauling every two years, while the operator arranges for overhaul every 500,000 kilometers according to the mileage of the train, which translates to about 3.3 years.

The investigation also found that the detached axle box and bearings were severely damaged, the internal lubricating oil was completely burned out, and the V-shaped spring wreckage was too damaged to determine whether these parts were already in danger. In other words, due to the severe damage to the key components, the investigation could not determine whether the accident was caused by bearing failure or whether the train was indirectly caused by uneven stress caused by the aging of the springs, which indirectly caused the axle box to overheat and fall off.

According to the report, the issue of "unnumbered" alerts had been reported by employees prior to the incident, but had never been resolved. Operators are also not trained on how to deal with such situations, resulting in an inability to make accurate judgments in the face of alarms. The frequent occurrence of false alarms in the past has also caused some dispatchers to become numb to such alerts and fail to act at critical moments.

The report stresses that if the operator had heeded the "unnumbered" alert at the time, the train might have had the opportunity to be withdrawn in time before it derailed.

It is reported that the Land Transport Authority imposed a fine of $3 million on SMRT.

Rail Transit Exhibition Booth Reservation

Rail Transit Exhibition Free registration for visit