Incident that caused MRT service disruption was a rare case, say experts

SINGAPORE: Experts told CNA that the train fault that caused an MRT disruption stretching across nine stations and now expected to last several days was a rare case.
On Wednesday (Sep 25), a component fell off a first-generation train, resulting in what authorities described as “extensive damage” to the train track and equipment between Clementi and Dover stations. This, in turn, caused a power trip that led to the disruption on the East-West Line, one of the two original lines built back in the eighties.
“Just like cars, (trains) have axle boxes; it’s very rare for (them) to drop. It’s very unfortunate and a very rare case,” said electrical engineering expert Teo Chor Kok.
Mr Teo said this was the first time he had heard of an axle box dropping off after becoming dislodged. Routine inspections of the train would have included the undercarriage area and the axle boxes, he added.
The axle box, which houses the bearings that allow the train’s wheels to rotate smoothly, is designed for heavy-duty use, said another expert.  
“Under normal circumstances, the axle box, bogie (an undercarriage with wheels) and train wheels do not come off from the train,” said Mr Jumadi Husani, the chief specialist for rail operations at Dubai’s Roads & Transport Authority.
If it does happen, it is mainly due to improper installation of parts after maintenance or testing activities or if defective components like damaged bolts or screws are not replaced, Mr Jumadi said.
At about 9am on Wednesday, a faulty first-generation Kawasaki Heavy Industries train that had been in service for more than 35 years was returning to Ulu Pandan Depot when its axle box became dislodged and dropped, said SMRT and LTA. 
This caused one bogie to come off the running rail between Dover and Clementi stations.
In turn, this severely damaged the track and track equipment, with 34 rail breaks across 1.6km of westbound tracks between Clementi and Dover stations. 
Three machines that are used to divert trains to different tracks, a third rail that supplies power, as well as power cables and rail clips were also damaged. 
This is what caused the power trip at about 9.25am on Wednesday, disrupting train services between Boon Lay and Queenstown MRT stations. 
When the axle box was dislodged, the train probably became unstable, causing it to move left and right on the rails, said Mr Teo, who is the managing director for Amega Asia.
Using the 34 rail breaks along the 1.6km of track as a gauge, he estimated that the train would have travelled for one to two minutes after the undercarriage came off the rails before stopping. 
Typically, the time taken for a train to come to a complete stop after the brake has been applied depends on several factors, including the speed of the train and whether the train is in automatic or manual mode, said Mr Jumadi.
In this case, the emergency brake should have been applied when the bogie came off the train, he added.
The train was not carrying any passengers since it was on the way to the depot, or the problem might have been caught earlier, said Mr Teo. 
As the power lines are typically located right next to the rails, the train’s movements damaged not only the tracks but also the power cables and other equipment, he added. 
With over 30 rail breaks and the time needed to conduct repairs, the damage seems “quite serious”, said Mr Teo. 
“I can only assume that with the momentum of the train, the bogie that came off would have been dragged along the track, which caused the damage,” added Mr Jumadi.
“However, the investigation currently being conducted will reveal more facts about what actually happened.”
On Thursday night, LTA and SMRT shelved plans to partially reinstate services between Jurong East and Buona Vista stations. Authorities had hoped to run a single-line train shuttle service between the two stations at 20-minute intervals.
But that was called off as operating the shuttle service would have slowed down repair work and risked full restoration of train services by at least a few days, said LTA and SMRT.
The calling off of the shuttle train service will likely mean the continuation of snaking queues for bridging buses. 
“(The shuttle train service) has a tremendous impact in alleviating long queues for buses, as one train carries (about) 1,200 passengers per way,” said Associate Professor Raymond Ong, a transport infrastructure researcher at the National University of Singapore
This is about 10 times the capacity of one double-decker bus, which can hold over 100 people. 
About 358,000 commuters were affected on Wednesday, according to information provided by LTA and SMRT.
It is estimated that on Thursday, about 516,000 commuters would be affected by the continued disruption.
However, the capacity provided by a shuttle service will fall far short of regular peak-hour services, where trains typically come every two to three minutes.
Thus, Assoc Prof Ong said that besides the 80 bridging buses that are rolled out, commuters should also be aware of free public bus services between Queenstown and Boon Lay stations, found at bus stops with yellow beacon lights.
“The public bus services, for example, those that ply along the MRT stations, that go out of the affected areas or to an area with train services … that are not affected by the disruptions – these can greatly increase the (public transport) capacity,” he said.