Experts question use of plastic ties

SINGAPORE - Even as they deemed the initial assessment of last week's major service disruptions reasonable and fair, transport experts yesterday questioned SMRT's use of plastic cable ties for short-term repair.

Those my paper spoke to felt that the transport operator should justify this move. The cable ties, along with steel support brackets, were used to secure the "claws", or metal grips, which had become dislodged.

An overnight joint investigation by SMRT and the Land Transport Authority (LTA) last Saturday revealed 21 missing claws along the North-South and East-West lines. These secure the "third rail", which supplies electricity to trains.

Associate Professor Lee Der Horng, a transport researcher with the National University of Singapore, said he believes SMRT will be looking for other ways to provide "even a temporary solution", because if further vibrations occur, the plastic cable ties would not be able to take it.

Transport analyst Tham Chen Munn, who is the director of Transport and Urban Design Consultancy Services, said: "Can any mechanical system that is subject to extreme loads and frequencies be secured with plastic cable ties?"

As a result of the dislodged claws, the third rail had gone out of alignment, preventing the collector shoes on the trains from getting power, according to preliminary investigations.

LTA officials also said on Sunday that the claws might have fallen off due to vibrations in some sections of the tunnel tracks.

Still, Dr Park Byung Joon, programme head of the Master of Science in Urban Transport Management at SIM University, said that other measures which have since been taken are a step in the right direction.

This includes imposing a speed limit on trains running through the city area, where most of the missing claws were found.

"Slowing the trains down is the only way to make sure impact (on the third rail) is minimal... For the time being, it's the right way to reduce vibration," he said.

However, experts agreed that other factors, including an increase in passenger load, should not be ruled out for causing the disruptions.

Prof Lee said: "More passengers means the train becomes heavier... At this stage, we cannot exclude (other) possibilities."

Mr Tham said: "An overload on any system, coupled with other factors such as wear and tear, can cause a chain of events."

Meanwhile, SMRT saw its shares fall as much as 3.6 per cent yesterday, to its lowest level in more than two months, reported Reuters.


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