Friday 25 May 2012

MRT breakdown COI: Day 27

SMRT unaware vibration would disrupt power
By Jermyn Chow. The Straits Times, 24 May 2012

RAIL operator SMRT was unaware of the damage that vibration from passing trains could inflict on its system until its train services broke down for the second time in two days last December.

Its vice-president for maintenance Ng Tek Poo told the Committee of Inquiry (COI) yesterday that the rail operator did not know that vibration could dislodge the metal claws holding the power supply third rail in place.

In last December's breakdowns which hit more than 200,000 commuters, third-rail claws that had come loose caused the third rail to sag, disrupting power supply to the trains.

After the second breakdown on Dec 17, Mr Ng said the SMRT management was 'puzzled as to why it happened again'.

It dawned on them only after an Australian vibration expert ran tests on its tracks. Mr Ng said: 'So I fully agree, vibration is a concern, yes. That was after the incident and we have done so many tests. But before that, we knew there was vibration... but we did not foresee that it could cause such damage to the system.'

COI panellist Lim Mong King, a professor at Nanyang Technological University's School of Aerospace & Mechanical Engineering, pointed out the flat spots on the metal wheels of many trains could have caused excessive vibration, damaging insulators and other parts.

Mr Ng, asked by inquiry chairman Tan Siong Thye why the problem of dropped claws was not reported to SMRT's top management, replied that it happened 'randomly and sporadically' and was a problem maintenance engineers could previously explain and solve.

The Chief District Judge then quipped: 'Mr Ng, if you had raised it and if you had dealt with that problem, we would not be here today.'

Going forward, Mr Ng said, SMRT will set up a system that measures track vibration levels so potential problems can be identified and fixed.

SMRT's senior management continued to defend the network's maintenance regimen.

Its deputy director of rolling stock and tracks Ng Wai Yi said that, even after the first breakdown on Dec 15, he was satisfied with the subsequent checks overnight and the next day on the tracks and the current collector devices. But the vice-president of rail operations Lui Wai Meng admitted that SMRT could have opted for other vibration-proof claw designs. 'We were not persuasive enough with the authority at that time,' he said.

SMRT has said it will change all claws to the latest fifth-generation ones.

The six-week hearing is likely to end tomorrow.


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