SINGAPORE: A system to detect the overheating of axle boxes – undercarriage parts linked to a train’s wheels – will be installed on all existing MRT lines by 2028.
These are the North-South, East-West, Circle, Thomson-East Coast, Downtown and North East lines.
The system will also be installed on the Jurong Region Line (JRL) by the end of 2030, the Land Transport Authority (LTA) said in a Facebook post on Aug 3.
The JRL will begin operations in stages between mid-2028 and 2029, with a new station between Tengah and Choa Chu Kang scheduled to open in the mid-2030s.
The axle box, which contains the axle bearings and connects the wheels to an axle rod, was at the centre of a major six-day rail disruption on the East-West Line (EWL) in September 2024.
Valued at about S$12.5 million, the contract to install the new system was awarded to Chinese railway safety equipment manufacturer Chengdu Shengkai Co. The system will monitor axle box and gearbox temperatures of passing trains using trackside infrared sensors. Installation is expected to begin in 2027.
The system will alert rail operators to any abnormal temperature increase so that necessary recovery measures can be taken to prevent faults from developing further.
It will also replace existing systems that detect overheating axle boxes across the rail network to standardise designs and parts used. LTA noted that this would streamline the management of spare parts and the provision of technical support.
At present, hot axle detection systems have already been installed by operator SMRT on its North-South and East-West lines (NSEWL), and by SBS Transit on the North East Line.
Two complementary systems will also be installed alongside the new detection system to improve fault detection capabilities.
The first, an acoustic detection system – to be installed only on the NSEWL and JRL – will use trackside microphone sensors and predictive analytics to detect early-stage damage to axle bearings.
The second is a hot wheel detection system that monitors the wheel temperatures of passing trains to enable the early detection of wheel and brake-related faults. This will be installed on all lines, including the JRL.
Axle bearings are mechanical components that allow the smooth rotation of train wheels.
Excess friction within the axle bearings, caused by degraded grease or deterioration of the rubber in the chevron springs, for instance, could lead to the overheating of an axle box.
Chevron springs are metal plates bonded together by rubber that absorb vibrations on moving trains.
The LTA tender for the supply of the hot axle box detection system was launched in October 2025 and closed in January 2026.
The Cross Island Line, which is expected to be ready from 2030, was not included in the tender as it is still under construction.
In the major incident on Sept 25, 2024, a section of a train carriage derailed after the axle box fell out.
Extensive damage was caused to 2.55km of track and trackside equipment as the train was withdrawn to Ulu Pandan Depot.
This disrupted MRT services between the EWL's Jurong East and Buona Vista stations for six days.
Based on investigators' findings, a sensor detected that an axle box on the train had reached a temperature of 118 deg C on the morning of the incident, well above the typical operating temperature of between 30 deg C and 65 deg C.
However, due to system issues, SMRT's heat detection tool was unable to identify the train that experienced the temperature increase. The issues were subsequently rectified. – ST/ANN
