Group of nine comb through list of recommended actions
By Christopher Tan, The Straits Times, 17 May 2012
A TEAM of experts engaged by SMRT, the Land Transport Authority (LTA) and the State yesterday went into the nitty-gritty of how to prevent a repeat of last December's MRT breakdowns.
They spent their second day at the Committee of Inquiry going through a list of recommended actions that they submitted on Tuesday - actions framed by a regimen of checks, maintenance and investment in better components.
The group of nine experts, mostly from Britain, paired their recommendations with 44 items, which were grouped into nine categories:
- Defective components;
- Third-rail crack at City Hall station;
- Third-rail crack at Orchard station;
- Third-rail sag;
- Vibration levels during train service;
- Vibration tests to determine conditions that can cause third-rail claws to drop;
- Claw design;
- Contributing factors to December's incidents; and
- Inspection processes.
The items comprise largely flaws identified in the team's findings to be the likely causes and contributing factors to the incidents last December.
Others are tests conducted to support those findings. For each of the 44 items, the experts listed one or more of the 21 recommended actions that they had earlier presented to the inquiry.
For instance, for the defective third-rail claw fastener found to have triggered the Dec 15 incident, the team said SMRT should 'develop and implement an improved method for detection of rail sag', referring to the collapsed third rail, which resulted in breakdowns on both Dec 15 and Dec 17.
For the third-rail crack at City Hall station, the panel recommended that the operator conduct 'non-destructive testing of fishplate joints of third rail on a prioritised basis, starting with incident sites'.
Along with that, SMRT and the LTA should 'develop risk-based protocol to identify actions to be taken when a (third-rail) crack is found'.
To prevent isolated incidents of third-rail sagging from worsening, the experts recommended two actions: that SMRT further tighten its maintenance regimen for the third rail, track and trains; and that it should develop and implement an improved method for the detection of rail sag.
Most of the suggested actions had the support of all the experts, but a few did not.
For instance, the team was divided over the item 'Phase I claw design adequate to continue in service'. This prompted the inquiry chairman, Chief District Judge Tan Siong Thye, to interrupt the discussion.
'It would help the committee if we can have some clarity,' he said, before asking the experts for precise views on whether the following were adequate supports for the third rail:
- 'First-generation' claws with no securing clips;
- Same claws with clips; and
- Same claws with cable ties.
Mr Roderick Smith (left), a research professor at London's Imperial College, said the first-generation claw was inadequate. 'I'm also concerned about using cable ties on an engineering design. It does not seem adequate in the long term,' he added.
But Interfleet Technology principal engineer Jerry Evans disagreed. 'Cable ties are inelegant but are effective,' he said.
'I can't accept the cost of going into tunnels and replacing all the fastener assemblies because I don't like the look of cable ties.'
Mr Huang Xianya, the chief consultant at Singapore-based testing laboratory TUV SUD PSB, said claws with clips are 'not absolutely effective' either.
In short, the experts could not make a unanimous recommendation on the best support design.
But they suggested that SMRT explore the latest third-rail support assemblies available to see which is the most robust and suitable.
The December breakdowns affected more than 220,000 commuters.
Review speed cap?
By Christopher Tan, The Straits Times, 17 May 2012
AN EXPERT hired by the Land Transport Authority (LTA) has suggested that SMRT considers lifting a speed limit imposed on trains after last year's breakdowns.
Mr Richard Greer (right), a director of engineering group Arup, told the Committee of Inquiry yesterday that the rail operator might do that even as it puts in place measures to make its network more reliable. He did not elaborate on this during the hearing, or when approached by The Straits Times later.
After the two breakdowns on Dec 15 and 17 last year, SMRT imposed a speed restriction of 40kmh on trains going past floating slab tracks (insulated sections underneath high-rise buildings that shield them from the noise and vibration of passing trains).
This was because it suspected that these sections were prone to more vibrations, and hence might cause metal claws holding the power-supply 'third rail' in place to dislodge. But vibration and noise experts testifying at the inquiry have said tests found no significant difference in vibration levels at floating slab tracks and other parts of the rail network.
Asked for comment on Mr Greer's suggestion, the LTA said it would 'review the speed restrictions with SMRT as the floating slab tracks have been ruled out as a contributing factor' to the December breakdowns. SMRT said it would ask the LTA to lift the restrictions 'once we are clear on what caused the claws to drop causing the disruptions in December'.
Hairline cracks: SMRT says rails safe but it'll do more checks
By Jose Hong, The Straits Times, 17 May 2012
By Jose Hong, The Straits Times, 17 May 2012
SMRT yesterday gave the assurance that the hairline cracks discovered on some third rail joints on the North-South and East-West lines do not affect the integrity of its rail or pose safety concerns.
But it said it will take the additional precaution of checking all 13,000 pairs of third rail joints that are in similar conditions to where the hairline cracks were found.
At the Committee of Inquiry hearing on Tuesday, experts said the power-supplying third rail of the two lines could have hairline cracks and asked for checks to be carried out at once. The cracks were discovered after last year's Dec 15 and 17 breakdowns.
The Land Transport Authority (LTA) has asked SMRT to check for cracks and replace third rails where cracks are visible, and to monitor the condition of third rail joints across the network.
Elaborating yesterday, an SMRT spokesman said that 'as the rail infrastructure belongs to LTA, SMRT has proposed and LTA has agreed for SMRT' to do three things:
- Change the third rails where cracks have been discovered
- Conduct weekly checks in areas where the cracks are minor and to monitor the condition of the rail.
- Use its multi-function vehicle and laser guns for regular checks to ensure that third rail joints are aligned.
SMRT said its current maintenance process, based on the manufacturer's recommendations, requires it to check only for visible defects. The hairline cracks discovered are hidden by a hulk-bolted fish plate which holds the third rail joints together and are not visible in routine inspection, it said.
Hence, in addition to these checks, it will seek to work with the LTA on a system-wide check for all 13,000 pairs of third rail joints in similar conditions to where the hairline cracks were found. The checks may include ultrasonic tests and will be completed in 18 months.
SMRT said the expenditure for what it will be doing on the third rail is included in the $900 million planned renewal and preventive maintenance works announced last month.
'Details on how the $900 million would be split between LTA and SMRT will have to be worked out and agreed on,' the spokesman said.
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