Independent party to do checks: LTA
ENGINEERS have yet to identify the root cause of Tuesday's massive train disruption, despite carrying out a comprehensive second round of checks.
In a statement yesterday, the Land Transport Authority (LTA) also said an independent consultant who specialises in transit power systems will be engaged to do the "overall conditional assessment of the entire power supply infrastructure and other railway trackside installations" from as early as this month.
Meanwhile, LTA and rail operator SMRT will continue checking the system.
During the second round of checks on Wednesday night, LTA and SMRT engineers conducted visual checks on all trains. Insulation testing between the cables and third rail was also carried out, to ensure that the test components of the power supply equipment are in good working order.
Data loggers monitoring the running rail voltage were also installed at specific points on the North-South and East-West lines, which experienced power trips.
"Despite carrying out a comprehensive second round of checks, we have yet to definitively identify the root cause of the disruption," LTA said.
Train services on the two lines were disrupted on an unprecedented scale on Tuesday, for more than two hours from around 7pm, causing commuters to be stranded during the evening peak hour.
It was the first time both the North-South and East-West lines were affected.
An estimated 250,000 commuters were affected that night as Singapore's two oldest and most heavily-used lines were crippled.
Many had difficulty finding alternative transport, even though additional buses were activated to cope with the crowds. Train services resumed later on Tuesday night, and continued to operate on schedule at normal speeds on Wednesday and yesterday.
SMRT said on Wednesday that it had identified three possible causes of Tuesday's breakdown: worn cable insulation, tunnel water leakage and a glitch in a power substation. Even so, it was "not 100 per cent sure" that they led to the breakdown.
SMRT has been in the spotlight following two major disruptions in 2011 which triggered a public inquiry.
National University of Singapore transport researcher Lee Der-Horng said that it was a "good sign" that engineers have been able to narrow down the possible causes of Tuesday's disruption.
"But even then, they could not be sure and my fear is that the root cause is none of the three. (If so), that would be quite problematic," he told The Straits Times.
Professor Lee and SIM University transport expert Park Byung Joon said it was important to understand how the flaws ended up affecting the whole network.
Said Dr Park: "The root cause could be something more fundamental, right down to the design and construction of the two lines. They may even need to look at the original blueprint. It would be good to have more manpower and a higher level of engineering expertise to find the root cause."