Human error compounded MRT disruptions on Oct 14: Ong Ye Kung

Human error compounded MRT disruptions on Oct 14: Ong Ye Kung

MRT service disruption Buona Vista (10)
Crowds at Buona Vista MRT station after a power fault disrupted train services on several lines on Oct 14, 2020. (Photo: Christy Yip)

SINGAPORE: An "honest mistake" was among the factors that contributed to the disruption of train services on Oct 14, said Transport Minister Ong Ye Kung in Parliament on Tuesday (Nov 3). 

Services on parts of the Circle Line were disrupted after an initial power fault affected the North-South East-West Line (NSEWL). 

The Land Transport Authority (LTA) had said in a report of the incident that to restore power to the NSEWL, an attempt to draw power from a substation was done - but this was conducted without first isolating the fault. A power supply disruption then occurred on the Circle Line, which is also served by the substation.

This was a human error, said Mr Ong, referring to the attempt to draw power from the Buona Vista Intake substation before isolating the fault.

He was responding to questions from three Members of Parliament - Tanjong Pagar GRC MP Joan Pereira, Bishan-Toa Payoh GRC MP Saktiandi Supaat and the Workers' Party's MP for Hougang Dennis Tan. 

They had asked about the causes of the disruptions, the lessons learned and whether emergency preparedness exercises are conducted on a regular basis to ensure that the relevant teams know what to do in the event of a power failure.

READ: MRT disruption on Oct 14 prompts system overhaul, with early weekend closures from November

"There are, in fact, many sets of SOPs to cater to different scenarios, but one thing we have learned over the years is that every disruption is different and unique. So besides being guided by SOPs, the engineers on duty will have to exercise judgment and make quick decisions during an emergency," said Mr Ong.

"I have not been in their shoes and cannot imagine the challenge they are facing. But under the pressure of time and circumstances, the personnel involved made an honest mistake," he added.

"I have no doubt this has been a major lesson for them, they wish they had decided differently, and they have much learning to share with their colleagues so that such a mistake will not happen again."

Timeline: How a power fault caused an hours-long disruption on three MRT lines on Oct 14

SMRT CEO Neo Kian Hong said last week that its employees misread the graphics display and thought that the fault had been isolated when they drew power from the Buona Vista substation.

The power staff member and his supervisor have been suspended and will be required to undergo retraining and recertification before they can resume duties, he said then.

Melted 22kv breaker trip coil MRT breakdown Oct 14
A melted 22kV breaker trip coil (Photo: LTA)

Responding to a supplementary question by Mr Tan on whether LTA will look into how rail operators can improve their work processes, the Transport Minister said that improvements will be made. He emphasised that suspensions are not uncommon as part of the safety protocol of organisations with a strong safety culture.

"Suspension does not necessarily mean we are blaming them or they're being punished because - make no mistake - if there is gross negligence, if there's wilful wrongdoing, disciplinary actions will be taken," he said. 

"Sometimes it is really a matter of retraining ... self reflect and go back and do better, and share your learning with your colleagues and I think it is a good system to ensure that we keep on improving."

CABLE FAULTS

Mr Ong also said that testing and inspection of power cables will be stepped up. The faulty cables are being investigated, he noted, adding that the results of the forensic examination are still unknown.

He added that there have been four power cable failures along the Tuas West Extension since 2018, and LTA and SMRT had earlier expressed their concerns to the supplier Alstom.

"On other lines, they typically have a lifespan of 20, 25, 30 years so this is a bit premature to have four faults in the last few years, which I think explains why Alstom is stepping forward, replacing everything," he said.

READ: Train services resume on North-South, East-West, Circle lines after disruption due to power fault

Giving more details on the earlier cable faults in response to a question by Leader of the Opposition Pritam Singh, Mr Ong said that two failures happened when the cables were first commissioned in 2018. The other two happened this year.

22kV cable faults in 2018 and 2020 MRT disruption
22kV cable faults in 2018 and 2020 (Image: LTA)

"The reasons for the failures have not been established which is why, given what has happened, we should send them for forensic (examination) and understand the reason why. In the meantime, regardless of the reasons, cables will be replaced."

EVACUATION OF TRAIN PASSENGERS

Mr Ong also went into the considerations behind whether to ask passengers to alight from stalled trains and walk along the tracks.

"Safety of commuters is the top priority during service recovery. That is why detraining commuters is always a last resort because to have commuters walking along the track poses risk, especially for those who are elderly or handicapped, and so it needs to be very carefully carried out," he said.

Replying to supplementary questions by Ms Pereira and Mr Saktiandi, Mr Ong explained that typically, a decision should be made as to whether to "detrain" passengers in a disruption, but there are many factors to consider.

"And then, like that night, there was inclement weather and there was lightning risk. Once there's lightning risk, you stop - never put passengers' lives in danger. So you're balancing between these two ... In this case, there was some hope that they could repower, but the repower went wrong."

He also said that evacuation on the Circle Line was faster than on the older MRT lines as it has a side platform where commuters can walk and wheelchairs can be used.

Typically on the NSEWL, the elderly, the wheelchair-bound and those with mobility issues have to remain on a stalled train until more manpower, including Singapore Civil Defence Force (SCDF) officers, arrive.

"If need be, we use stretchers to carry such passengers to the nearest station. The stations are also equipped with battery-powered motorised trolleys," he said.

He added that the passengers have to walk beside a high voltage third rail, and they might trip.

"You got to make sure you disable it - double confirm, triple confirm, quadruple confirm because it is no joke walking next to 750 volts," he said. 

MRT service disruption Oct 14
Passengers on a train near Kranji on the North-South Line towards Woodlands evacuated after a power fault disrupted the MRT service on several lines on Oct 14, 2020. (Photo: Julie Chan)

The Operations Control Centre has to balance such risks against the discomfort and heightened anxiety of commuters on the stalled trains and as far as possible, it will try to restore power to the trains to bring commuters to the nearest station, said Mr Ong.

However, 40 minutes into the disruption, the centre concluded that it could not restore power to the system quickly and decided on "detrainment", he added.

In all, 6,800 commuters on the stalled trains were brought to the nearest station platform in under an hour, except for 78 people who were trapped because of the bad weather and risk of lightning.

Mr Ong concluded that there were many lessons to be learned from the incident, noting that mass rapid transit systems are very complex and when a major disruption occurs, the circumstances and causes are often unique.

"With the recent disruption, the morale of the teams on the ground has been affected ... There are many honest and hardworking people who have toiled over the past few years to make our MRT services among the most reliable in the world," he said.

"So as a team, we take collective responsibility, not finger point, and we will do our best, close the gaps, address the shortcomings."

Source: CNA/hm(gs)

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