Advertisement

Why Circle Line broke down: SMRT

A faulty cable and tunnel leakage caused the Circle Line’s four-hour delay on the morning of 20 September, said SMRT on Wednesday.

In a meeting with the media on Wednesday afternoon, SMRT’s executive vice-president for trains Khoo Hean Siang said it was the first time the train operator experienced a power fault of such a nature and scale.

And with the full Circle Line MRT service to launch in 10 days, SMRT is now inspecting all of its stations for faulty power cables. Checks on Lines Four and Five — which are the new lines to be opened next Saturday — are complete, and staff have to inspect 16 more stations along the older lines.

Yahoo! Singapore understands that so far, another two faulty cables have been found along the new lines and replaced. The checks will be completed by next Saturday.

The Land Transport Authority oversaw the initial installation of the cables.

Explaining last Tuesday's breakdown, Khoo said a damaged power cable was installed under the Dakota station train tracks, in the direction heading toward Dhoby Ghaut. The wires inside the cable were then exposed to water that had seeped into its encasing pit due to tunnel leakage.

Tunnel leakage is a common occurrence in SMRT’s train lines but had not caused problems at its main North-South and East-West lines because those lines were equipped with a drainage system.

Over time, the cable deteriorated and finally broke completely at 5:27am last Tuesday. This caused a power trip in the circuit breaker at Dakota station and cut power to the entire Circle Line.

To uncover what had happened, Khoo said engineers systematically isolated and tested sections of the 36-kilometre rail on the tracks before they identified the affected cables at Dakota station.

“We had to identify, isolate and physically remove the cable from the third rail, and then reroute power to it from the adjacent stations (Mountbatten and Paya Lebar),” said Khoo, adding that when he visited the site, he also observed that the water in the cable pit was heated and staff detected a burning smell from the cable.

“We have since combed through the whole system (for more faulty cables),” he said. “Our staff are working (every night) over the past few days, and are working closely with the LTA to complete (these checks) before the opening of Circle Lines 4 and 5.”

Last Thursday, Transport Minister Lui Tuck Yew said he had called for LTA to thoroughly investigate the Circle Line breakdown.

Khoo also noted that insulation for the cables are checked every six months and the cables on the Circle Line were inspected in June. “It had passed all the tests,” he said.

Why trains are delayed and fares are rising

SMRT also explained why commuters may have experienced an increase in the number of train delays exceeding five minutes — from an average of two out of every 100,000km travelled at the beginning of last year to slightly more than four in July.

Its vice-president of maintenance Ng Tek Poo said that about a quarter of its delays are caused by factors beyond the operator’s control, such as mechanical objects preventing its doors from closing or passengers triggering emergency alarms, as well as wet weather that affects above-ground tracks.

The other 75 per cent, according to Ng, arise from technical faults, in particular, due to teething issues after new trains or technology like the half-height platform screen doors are introduced.

When the screen doors were first introduced last September, the number of delays rose steadily over the next four months to peak at more than four delays per 100,000km before dropping back to slightly more than two delays per 100,000km.

Issues included the misalignment of platform doors and premature failure of belts that controlled the timing of the doors' opening.

The increase in the frequency of train services during peak hours on weekdays also means there is a higher chance of faults occurring.

“We are pushing our train services to the limit (during peak hours),” said Ng. With 103 trains in operation during peak hours, there is almost one train at every station at any one point in time.

A total of 22 new trains will be introduced by the end of this year so commuters could expect more delays, said Ng. But he was quick to assure that SMRT staff are working to rectify problems as soon as they arise.

“Interim solutions have been implemented and faults have since been significantly reduced,” said Ng. For instance, LTA and SMRT are working with the half-height platform screen door manufacturers to rectify defects.

Ng also explained that the hefty cost of maintenance, coupled with the rising energy costs, led to the need for increased train fares.

He said for every dollar paid in train fares, 25 cents is directed to maintenance, which excludes the manpower cost of the 1,700 maintenance crew needed.

As SMRT continues to work out the kinks in its system, SMRT’s Khoo stressed, “The safety of our passengers always comes first.”