Queries on pre-service rail checks
Multi-function vehicle used to check third rail reported loss of readings
By Royston Sim, The Straits Times, 3 May 2012
EARLY on Dec 17, SMRT maintenance officer Shamsuri Mohamad and a colleague jointly combed 900m of the south-bound track between Newton and Orchard stations.
The Committee of Inquiry (COI) heard yesterday that they squatted down more than 100 times along that stretch to make visual checks of the third rail claw assemblies and joints.
They spotted no abnormalities.
The second major disruption to the train service in three days was to happen hours later, inconveniencing more than 90,000 commuters over the next seven hours.
This was later found to have been caused by a portion of the third rail on the south-bound track between Newton and Orchard stations sagging and damaging the collector shoes on several trains, causing them to stall.
The focus of the COI yesterday, Day 12 of the public inquiry, centred on whether SMRT maintenance workers might have missed something during their checks before the start of service.
Six of them took the stand yesterday.
It turns out that it was not exactly business as usual that Dec 17 morning.
Some employees had earlier reported that a multi-function vehicle (MFV), used to measure whether the third rail is correctly aligned, had reported a loss of readings on two stretches of the south-bound track between those two stations. The MFV, installed with side mirrors to do this measurement, was reported to have developed a crack in one of its mirrors.
It was after this that Mr Shamsuri, 56, and his colleague were instructed to inspect the track and third rail.
In his report to line manager Isman Seymo, Mr Shamsuri said he found nothing amiss during the check, which he completed in 20 minutes.
Two COI members and the state counsel querying him expressed doubt that 900m of track could be inspected that quickly, and asked him whether he had actually checked every third rail claw assembly in that time. Mr Shamsuri stuck to his guns, saying it was possible to do so, and that he had done the inspection thoroughly and yet found nothing abnormal, although the cause of the loss of readings on two stretches of the track that morning remained unaccounted for.
The COI then moved to Mr Isman, 48, to ask him why he did not flag the cracked MFV mirror to his superiors, and whether the cracked MFV mirror was a sign of an abnormality.
COI member Soh Wai Wah, director of prisons, asked him: 'In the light of what happened on Dec 15, were alarm bells not ringing in your head?'
Mr Isman said he was not alarmed, and that his job was just to attend to requests made by the MFV operator.
Earlier yesterday, the COI was told that an incorrect data entry to the MFV had resulted in readings being off by about 100m. The inaccurate readings led to MFV operator Yew Kai Png identifying the wrong stretches of track for the manual inspections.
Besides their observations on the cracked mirror and what might have caused it, those who testified were asked about the tests they ran that night and MFV maintenance procedures.
The hearing continues today.
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