Thursday 24 May 2012

MRT breakdown COI: Day 26

Witness offers contradictory evidence
By Christopher Tan, The Straits Times, 23 May 2012

THERE were more questions than answers in court yesterday as the 111th witness of the Committee of Inquiry failed to corroborate a number of statements gathered so far.

In some instances, SMRT deputy director of rolling stock and tracks Ng Wai Yi even offered contradictory evidence, to the bewilderment of the court.

Mr Ng was first quizzed by the Attorney-General's Chambers (AGC) on the number of trains inspected at the Changi, Ulu Pandan and Bishan depots for damage to their current collector devices (CCDs) after the first breakdown on Dec 15 last year.

Mr Ng said SMRT had collated numbers from two shifts - evening and night - when it should have just done so from the night shift.

He also said he needed to check on three trains that had returned to the Bishan depot earlier in the day, as he was not certain if their CCDs had been checked.

An earlier witness had said all trains already in the depot that day were checked, but did not provide proper documentary evidence besides a handwritten note to prove it.

After the second breakdown on Dec 17, SMRT did a second check of the tracks.

The AGC asked if the crew members of a track-gauging vehicle were asked to check a stretch of tunnels between Orchard and Newton that were not covered earlier, but Mr Ng could not say if they were or not.

Asked who else in SMRT knew of this stretch being left out besides himself, the deputy director could not answer that question either.

Mr Ng was also unable to account for 'fresh scratches' on the power-supplying third rail detected after the second incident.

When Second Solicitor-General Lionel Yee, representing the AGC, put it to him that the team tasked with moving the damaged or twisted CCD shoes out of the way so that they would not come into contact with the third rail 'did not succeed', Mr Ng explained that the team worked when the trains were stationary.

He said when the trains are in motion, 'we're not certain about the dynamics of... dangling shoes'.

The inquiry, now into its sixth week, has yet to nail down evidence pointing to the cause of the second incident on Dec 17.

One theory is that trains with damaged CCDs - sustained on Dec 15 - had come into contact with and dislodged third rail supports and caused the conductor rail to collapse.

But this does not explain why trains ran fine on Dec 16.

Mr Ng was also unable to say why the back-up batteries on train 139 fell short of the minimum duration of 45 minutes.

He later pointed out that the first CCD shoe of train 139 was not damaged - contrary to earlier evidence presented by a panel of rail experts.

With the single shoe intact, Mr Ng said, the driver's carriage would still have air-conditioning and full lighting, and that might explain why the driver was unaware that the last three cars had neither.

The biggest mystery of the day, however, had to do with train 123, which stalled at Bishan station on Dec 17. It had one undamaged CCD shoe per car, which technically meant it still could move.

Mr Ng said that it might be because one compressor unit had failed, but 'I can't say with certainty whether that caused the train to stall'. He had earlier in the day said that as long as one out of two compressors on a train worked in such a situation, it would move.


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