SMRT 'not 100% sure' of root cause of breakdown

Train services on the East-West and North-South Lines recovered yesterday morning after a major breakdown on Tuesday evening.

They were crippled because a safety device was triggered, causing power supply to trains to be cut off, said SMRT's managing director of trains Lee Ling Wee.

Commuters had to look for alternative transport options until train services resumed 3½ hours later.

Tuesday's incident is the first time train services on both lines broke down at the same time.

It also marks the worst disruption for SMRT since Dec 15, 2011, when train services were down for about six hours on the North-South Line between Bishan and Marina Bay, affecting about 127,000 commuters.

Two days later, train service on the North-South Line was disrupted between Toa Payoh and Marina Bay, affecting about 94,000 commuters.

SMRT, however, is still not "100 per cent sure" of the root cause of Tuesday's breakdown.

Mr Lee narrowed it down to three possible causes, which he shared at a joint press conference with the Land Transport Authority (LTA) yesterday.

TRACK

The power cables that connect to the third rail could have been damaged, causing a power trip that triggered the safety device. The third rail is a conductor that runs alongside the entire track and provides electricity to each train.

POWER SUBSTATION

Something faulty at the power substation, where power runs through cables to the third rail. TRAIN

Something broken dangling from the train that touched the third rail, causing the power to trip. SMRT has since ruled out this cause after checking all the trains on Tuesday night.

On the same night, three faults were also found and rectified, Mr Lee added. The faults were:

The insulation of two power cables along the North-South line was damaged.

A faulty relay system (an electrical device activated by a current or signal in one electric circuit to open or close another circuit) was found at Kranji's power substation.

There was water leakage along a section of the Tanjong Pagar tunnel, close to a third rail insulator.

Train services resumed without a glitch after these faults were rectified, but it is not clear if they had a "system-wide effect" on the rail network, said SMRT chief executive Desmond Kuek.

The faults found in SMRT's investigations were not identified during routine maintenance checks, which are conducted every six months or yearly, Mr Lee conceded.

He said that in an ageing system, some of the train parts may fail in between the interval checks.

The train operator is looking at monitoring devices that can identify faults on a real-time basis, Mr Lee added. It is also considering stepping up the frequency of checks.

LTA's chief executive Chew Men Leong added that a new voltage-limiting device has been piloted for Downtown Line 1, which can contain power trips into smaller zones.

Mr Lee said it will take some time for SMRT and LTA to look through all the data becoming coming up with a solution.

Mr Chew also promised to leave no stone unturned in this investigation.

TIMELINE

5.59pm SMRT detects first traction power trip, but it can be reset by Operations Control Centre (OCC), not affecting commuter service.

6.03pm 20 other such power trips detected across the rail network. SMRT activates the engineering and operations teams and puts buses on standby.

6.52pm OCC detects a power trip that has to be manually reset at the power station. A segment of the track is affected, stalling five trains.

7.06pm Two more such power trips. Arrangements are made for passengers to detrain at stations. Free bus services are provided.

7.34pm SMRT starts investigations.

8.10pm Tests are conducted to determined if the power trip is track-related or train-related.

9pm Service on East-West Line resumes, but with fewer trains running.

9.35pm Train service on North-South Line resumes, but with fewer trains running.

1.38am The last train clears the North-South and East-West Lines.

2.10am Island-wide free bus service ends.

'We'll try to minimise the road bumps'

MRT BREAKDOWN CHAOS

SMRT chief: There will be unexpected incidents in effort to improve rail reliability

With changes introduced to existing systems while they are running live, unexpected incidents can occur.

And when that happens, there is a certain degree of fire-fighting to be done, said SMRT chief executive Desmond Kuek.

"In the journey to recovering and bringing about a higher level of rail reliability, unfortunately, there will be some of these road bumps... that we will have to try to minimise and mitigate," he said.

Mr Kuek was speaking yesterday at a joint press conference with the Land Transport Authority (LTA) to address the rail breakdown on Tuesday evening.

Both he and LTA chief Chew Men Leong apologised for the major train disruption on the North-South and East-West Lines.

DIFFICULT

Mr Kuek said the incident was a "stark reminder" that the journey to bring about a highly reliable train service expected by commuters is difficult, but reiterated SMRT's commitment to this.

Mr Chew also acknowledged the severity of the incident, saying: "This is obviously a serious disruption. It is also the first time we had disruption on the East-West and North-South lines altogether at the same time...

"Again, I think our focus right now is really to go down to investigate really what the root cause of the power trip (is), and getting to know what were the contributing factors... (so that we could) rectify them and... minimise a re-occurrence."

Minister of Transport Lui Tuck Yew, who was at Ang Mo Kio MRT station yesterday morning to observe the running of the trains, shared the same sentiments.

But rather than calling for a Committee of Inquiry into the incident, he said it will be more useful for SMRT and LTA to focus on finding the exact cause of what went wrong.

Some previous train disruptions

MRT BREAKDOWN CHAOS

MARCH 9, 2015

A power trip between Pending and Jelapang stations caused a service disruption on the entire Bukit Panjang LRT line, at around 5.30pm.

A fire then broke out inside the electrical room of Senja station at around 5.45pm.

No one was injured but train service was not resumed for the rest of the evening. Full service was restored only at 5.30pm the next day.

FEB 23, 2015

A train stalled on the open viaduct between Yew Tee and Kranji stations on the North-South line.

The fault was due to a damaged third rail which supplies power to the trains.

Services were disrupted from 3.07pm to 7.33pm and passengers were transferred to Yew Tee station.

OCT 25, 2012

About 10,000 passengers were affected as faulty power cables caused service disruption throughout the entire Circle Line in the evening.

It happened at 10.26pm, and 102 commuters who were onboard a stalled train between Promenade and Bayfront stations were guided safely to the nearby Bayfront station.

Services were partially resumed around 11.20pm between HarbourFront and Paya Lebar, but only fully restored the next morning at 5.30am.

DEC 17, 2011

94,000 commuters were affected during a train service disruption that lasted seven hours and damaged seven trains.

The disruption lasted between 6.50am and 1.48pm, and across 12 stations from Ang Mo Kio to Marina Bay.

Most commuters could get off at station platforms, but 500 who were onboard a stalled train were guided to walk about 150m in the tunnel to Somerset station.

DEC 15, 2011

A faulty third rail caused a train disruption between Bishan and Marina Bay in the evening.

Lights went out in some train cabins and a 41-year-old woman reportedly fainted onboard due to a lack of ventilation.

Services resumed at 11.40pm and around 127,000 commuters were affected in total.

OCT 17, 2011

Services on two MRT lines were disrupted in the morning.

At 10.27am, a train fault disrupted service between Ang Mo Kio and Bishan stations on the North-South Line.

Full service resumed only at 12.05pm and more than 7,000 commuters were affected.

On the Circle line, a train also had to be taken out of service due to a train fault between Labrador Park station and Pasir Panjang station. Service was disrupted from 8.36am to 11.12am.

This article was first published on July 9, 2015.
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