NSL disruption: Malfunctioning water pumping system resulted in flooded MRT tunnel, says LTA

Channel NewsAsia 8 Oct 17;

SINGAPORE: A water pumping system malfunction led to the flooding of the MRT tunnel between Bishan and Braddell stations and the delay of train services on the North-South Line (NSL), according to a statement by the Land Transport Authority (LTA) on Sunday (Oct 8).

A torrential downpour caused a section of the tunnel between the two stations to be flooded on Saturday afternoon, halting service on half the NSL - from Ang Mo Kio to Marina South Pier - for more than 3 hours.

Train services in both directions were suspended between Ang Mo Kio and Newton MRT stations for almost 20 hours before they resumed at 1.50pm on Sunday.

Preliminary investigations have indicated that water entered the tunnels through a "portal opening" near Bishan MRT station where rail tracks that are above ground descend underground, LTA said.

"Under normal circumstances, rainwater runoff accumulated in the adjacent storm water sump pit would have been siphoned off by a system of pumps," said LTA.

However the water pumping system malfunctioned, causing rainwater to overflow from the collection pit into the tunnel and to collect at the tunnel's lowest point, between Bishan and Braddell stations.

As a safety measure, transport operator SMRT immediately deactivated the trackside power supply, said LTA.

It added that the pump system has since been repaired, and that investigations into the incident are ongoing. Checks have also been carried out on other portal pump systems located along the NSL and East-West Line.

Officers from the Singapore Civil Defence Force (SCDF) and national water agency PUB worked through the night along with LTA and SMRT staff members to clear water from the flooded tunnel. SBS Transit was also on standby to support their efforts.

"Affected trackside equipment was subsequently inspected, cleaned, replaced and tested before passenger services resumed," said LTA.

In a Facebook post, SCDF said that the water was cleared at 11am on Sunday.

In its statement, LTA said that it was also investigating the small trackside fire which happened between Marina Bay and Raffles Place MRT stations on Saturday evening.


NSL train disruption: Malfunctioning water pump system to blame for flooded tunnel
Today Online 8 Oct 17;

SINGAPORE — A water pumping system that broke down was to blame for the MRT underground tunnel flooding that completely shut down train services along six stations on the North-South Line (NSL) from Saturday evening to Sunday (Oct 8) afternoon, affecting thousands of commuters in one of the worst outages since 2011.

The Land Transport Authority (LTA) revealed this in an update Sunday evening, although it said it was still looking into how this had happened. Details on when the water pumping system, which should have siphoned off rainwater buildup in an adjacent sump pit, was last maintained were not given.

The malfunction allowed water to overflow from the storm water sump pit during a torrential downpour on Saturday afternoon, and enter the tunnel through the rail tracks where trains from Bishan MRT station go underground towards Braddell MRT station.

SMRT, which operates the NSL, was forced to deactivate the trackside power supply as a safety precaution, halting services from Ang Mo Kio to Newton, both ways, from 5.33pm. The clearup of the flooding in the tunnel involved officers from the Singapore Civil Defence Force (SCDF) and PUB working overnight alongside LTA and SMRT officers, and took nearly five hours longer than initially hoped. Normal service resumed at 1.50pm Sunday, after the water pumping system was repaired, and trackside equipment were inspected, cleaned, replaced and tested.

The LTA said checks have also been conducted on other tunnel portal pump systems located throughout the North-South and East-West Lines (NSEWL), the Republic’s two oldest and busiest MRT lines.

SCDF gave the public the first glimpse of the incident when it released a set of pictures on Facebook showing its personnel wading in almost knee deep water in pitch dark conditions as they worked to clear the water through the night on Saturday.

Their operation concluded after the water in the tunnels were completely cleared at approximately 11am on Sunday.

Before the cause of the incident was released by the authorities, commuters wondered why the flood protection works, such as barriers at entrances to keep out floods below 1.5m, carried out at 35 existing stations — including Braddell and Bishan — had failed. They also expressed concern that another downpour would result in another outage, especially during the work week, and given that heavy thunderstorms are forecast on Monday morning and the coming days.

The weekend’s unprecedented incident of a train disruption caused by flooded tunnels is possibly the worst disruption since December 2011, when over 200,000 commuters were affected by a major service disruption along the NSL over two days.

On Dec 15 that year, an estimated 127,000 commuters were affected by a major service disruption along the NSL from Marina Bay station to Braddell station.

At that time four trains stalled because of a misalignment between the train’s current collector shoes and the power rail, also known as the third rail. The trains draw locomotive power from the third rail through the train current collector shoes. As there was a misalignment, the trains were unable to draw power and thus stalled.

Two days later, another service disruption took place on the same line during the morning and affected about 94,000 commuters. During this disruption, five trains stalled after encountering similar mechanical problems. SMRT was only able to resume service around noon a day later.


SMRT restores train services on NSL after flooded tunnels cause disruption for over 20 hours
Today Online 8 Oct 17;

SINGAPORE —Train services between Newton and Ang Mo Kio stations on the North-South Line (NSL) have resumed, SMRT said on Sunday (Oct 08), about 20 hours after rain water flooded tunnels and crippled train operations.

In an update on its Facebook page, SMRT said that train services in both directions resumed at 1.50pm.

“This follows an all-out, overnight effort to clear water in the tunnels between Bishan and Braddell MRT stations,” said SMRT, adding that teams from the Singapore Civil Defence Force, PUB, Land Tansport Authority and SMRT worked jointly to pump out water from the tunnels.

On Saturday night, teams from SMRT and LTA also conducted network-wide checks on MRT tunnels.

“SMRT thanks the various agencies for stepping in to assist since yesterday. In addition, the Singapore Police Force assisted with traffic control and crowd management along roads and at affected stations, and SBS Transit provided additional buses for the bridging bus services,” it said.

“We are very sorry for the inconvenience commuters had to bear this weekend.”

This weekend's transport chaos began around 5:33pm on Saturday, when SMRT halted train services between Bishan and Toa Payoh MRT stations "as a precaution" due to flooding in the tunnel from Bishan to Braddell MRT stations, following a heavy downpour. In a separate incident, a small fire on the trackside in the tunnel between Marina Bay and Raffles Place MRT stations was also reported, though the flames later died out on its own.

The tunnel was reportedly flooded despite flood prevention measures having been improved recently. Currently, flood barriers at 35 underground MRT stations have been completed across the network.

Also posting on its Facebook page on Sunday afternoon, SCDF said it received a call from SMRT at approximately 7.07pm on Saturday evening requesting assistance for a flooding situation in the tunnels between Braddell and Bishan MRT Stations.

Releasing the first set of official images following the incident, pictures showed SCDF personnel wading in almost knee deep water in pitch dark conditions as they worked to clear the water.

The SCDF said: “In a protracted overnight operations, SCDF Emergency Responders worked closely with the engineering teams from LTA, PUB and SMRT to pump out the water from the affected areas.”

It added that at approximately 11am on Sunday, the water in the tunnels had been completely cleared and SCDF has concluded its operations.

Commuters interviewed by TODAY welcomed the resumption of services, while adding that long term improvements are needed.

Mrs Koh, 55, said when interviewed at Bishan station: “I’m happy for everyone that the service has resumed”.

“Over the years, flooding has been well controlled in Singapore in my opinion. For something like this to happen, I think it is (a) very big (deal),” she said.

Her son, Mr Koh, 27, added: “It has become sort of like a gamble. Every time you take the train, you have no idea like whether it is going to come. People are slowly moving to alternative methods of transport like Grab.”

Mr Nam Hayul, 16, hoped that commuters can be more understanding.

“The delay is not on purpose from SMRT’s end… Although it has affected almost everyone. Hopefully, they can improve on their system.”

In an earlier update just after 10am on Sunday, SMRT said that the rain water that flooded the tunnels and crippled operations from Saturday evening is "almost cleared".

"We are working towards full resumption of North-South Line train services as quickly as possible," SMRT had said.

Initially, SMRT planned to re-open services between Newton and Ang Mo Kio stations at 9am on Sunday.

Train services on the NSL from Jurong East to Ang Mo Kio, and from Newton to Marina South Pier stations in both directions were unaffected.

The disruption is possibly the widest outage since December 2011, when over 200,000 commuters were affected by a major service disruption along the NSL over two days.

On Dec 15 that year, an estimated 127,000 commuters were affected by a major service disruption along the NSL from Marina Bay station to Braddell station.

At that time four trains stalled because of a misalignment between the train’s current collector shoes and the power rail, also known as the third rail. The trains draw locomotive power from the third rail through the train current collector shoes. As there was a misalignment, the trains were unable to draw power and thus stalled.

Two days later, another service disruption took place on the same line during the morning and affected about 94,000 commuters. During this disruption, five trains stalled after encountering similar mechanical problems.

SMRT was only able to resume service around noon a day later.

Timeline of NSL disruption due to flooded MRT tunnel
Channel NewsAsia 8 Oct 17;

SINGAPORE: A torrential downpour on Saturday (Oct 8) afternoon wreaked havoc on train services on the North-South Line (NSL), causing a section of the tunnel between Braddell and Bishan MRT stations to be flooded.

Service on half the NSL - from Ang Mo Kio to Marina South Pier – was halted for more than 3 hours. Train services in both directions were suspended between Ang Mo Kio and Newton MRT stations for almost 20 hours before they resumed at 1.50pm on Sunday.

Here’s a look at the timeline of events:

SATURDAY

5:33pm: Train services halted between Bishan and Toa Payoh MRT stations after a section of the tunnel between Bishan to Braddell MRT stations flooded following a heavy downpour.

5.36pm: SMRT tweets that “due to a track fault”, there is no train service from Bishan to Toa Payoh towards Marina South Pier.

It adds that this is not linked to a project to upgrade the signalling system along the NSL.

5.55pm: An SMRT train captain reports a small fire on the trackside in the tunnel between Marina Bay and Raffles Place MRT stations. SMRT later says the Singapore Civil Defence Force was activated within minutes to Marina Bay. However, the fire had died out by itself, SMRT says.

6.05pm: SMRT announces on Twitter that train services in both directions between 13 stations from Ang Mo Kio to Marina South Pier are suspended. For safety reasons, North-South Line train services between Ang Mo Kio and Marina South Pier are not available.

7.32pm: SMRT gives first confirmation that the NSL train services were disrupted due to “water in the tunnel from Bishan to Braddell MRT stations”.

9.22pm: Train services between Newton and Marina South Pier are restored.

10.45pm: SMRT says train services from Newton to Ang Mo Kio stations in both directions are not available till end of service on Saturday. It says engineers will carry out network-wide tunnel checks throughout the night.

SUNDAY

6.09am: Service between Newton and Ang Mo Kio stations still not restored. SMRT says it is striving to resume service at 9am.

8.32am: SMRT says work to clear water in the tunnels between Bishan and Braddell MRT stations is still in progress and the effort requires more time.

10.09am: The water between Braddell and Bishan MRT stations is “almost cleared” thanks to overnight efforts from teams from the SCDF, PUB, Land Transport Authority and SMRT.

1:52pm: SMRT announces that train services in both directions between Newton and Ang Mo Kio MRT stations resumed at 1:50pm.

Engineers will deploy several empty trains on the tracks between Newton and Ang Mo Kio for final safety checks before passenger services resume, SMRT says.

1.56pm: SCDF releases first photos of the flooded MRT tunnels and says the water was cleared from the tunnel at 11am. It received a call for assistance from SMRT at 7pm, it adds.

5.07pm: A water pumping system malfunction resulted in flooding between Bishan and Braddell stations, according to preliminary investigations by the Land Transport Authority. The pump system has since been repaired, it adds, and investigations are ongoing.


Bishan, Braddell MRT stations among 35 flood-proofed in recent years
Today Online 8 Oct 17;

SINGAPORE — The unprecedented flooding in MRT tunnels along the North-South Line that halted services along a stretch of stations for some 20 hours over the weekend has thrown up questions of what had gone wrong, and whether a repeat could happen.

Operator SMRT said on Saturday (Oct 7) evening that the flooding at neighbouring MRT stations Bishan and Braddell “occurred during torrential rain this afternoon”.

But the two stations were among 35 underground MRT stations across the network to have had flood protection measures installed since 2012.

The flood-protection measures put in place include the installation of barrier systems — similar to what is done in Hong Kong’s MTR stations — at several points in each station to keep flood waters below 1.5m out. Glass panels, vent shafts and other openings were also sealed to make them watertight, while escape staircases were raised.

Earlier this year, the Land Transport Authority said that “with the completion of these works (at the 35 stations), all current and future MRT projects, including those on Downtown Line and Thomson-East Coast Line, will meet the requirements for flood protection as specified in PUB’s Code of Practice for surface water drainage”.

In 2006, after an early morning downpour, the Novena MRT station had waterlogged floors and a dripping ceiling. The water, which flooded the floor by a height of 5cm, appeared to have come from a nearby construction site.

While train services were not affected at the time, staff from other stations arrived to shelter commuters with umbrellas and mop up the mess. To prevent the water from damaging the electrical systems, the escalators, fare gates and lift were switched off.


NSL disruption: Water pumping system malfunction at Bishan MRT station caused tunnel to flood, says LTA
Yuen Sin Straits Times 8 Oct 17;

SINGAPORE - A malfunction in the water pumping system at Bishan station caused water to collect in the MRT tunnel, contributing to train service disruption along the affected stretch of North-South line on Saturday (Oct 7) that lasted close to 21 hours.

In a statement to the media on Sunday, the Land Transport Authority (LTA) said that preliminary investigations showed that water had entered the tunnel through the portal opening near Bishan MRT station, where above ground rail tracks transit underground, after a torrential downpour.

"Under normal circumstances, rainwater runoff accumulated in the adjacent storm water sump pit would have been siphoned off by a system of pumps.

"Yesterday, the water pumping system malfunctioned, resulting in rainwater overflowing from the storm water sump pit into the tunnel opening and accumulating at the lowest point of the tunnel, between Bishan and Braddell stations," said an LTA spokesman.

SMRT immediately deactivated the track side power supply as a safety measure. The pump system has since been repaired.

Trains in operation at Bishan MRT station at 3.20pm on Sunday (Oct 8). Water had entered the tunnel through the portal opening near the station. ST PHOTO: KEVIN LIM

Checks have also been conducted on other tunnel portal pump systems located throughout the North-South and East-West lines, added the LTA spokesman.

Detailed investigations into the cause of the disruption are ongoing. The disruption affected thousands of commuters travelling on a large stretch of the North-South Line from Ang Mo Kio to Marina South Pier for more than four hours on Saturday night.

The disruption was also made worse by another incident, a track side fire between Marina Bay and Raffles Place stations. LTA said that the fire was unrelated to the earlier incident, and it is investigating its cause.

While much of the train service was eventually restored on Saturday, the two-way service between Newton and Ang Mo Kio resumed only on Sunday at about 1.50pm.

LTA said that officers from the Singapore Civil Defence Force and national water agency PUB worked through the night alongside officers from the LTA and SMRT officers to clear the water, with SBS Transit also on standby to support the recovery efforts.

"Affected track side equipment was subsequently inspected, cleaned, replaced and tested before passenger services resumed," said LTA.

During the service disruption, free regular bus and bus bridging services were activated, with more than 40 buses from SMRT and SBS Transit deployed to provide bus bridging services, it added.


Experts call for more measures after North-South Line MRT disruption
They suggest having more checks and a backup system after pump malfunction results in flooding in tunnels
Felicia Choo, Yuen Sin Straits Times 9 Oct 17;

Transport experts have called for more measures to be taken to prevent a repeat of a nearly 21-hour disruption of North-South Line train services over the weekend, one of the worst here since 2011.

A malfunction in a water pumping system had caused flooding in the MRT tunnels, which contributed to the disruption.

Experts said more checks and having a backup system could prevent a repeat of the incident.

Thousands of commuters on a 13-station stretch of the North-South Line, from Ang Mo Kio to Marina South Pier, had to delay their plans or make alternative travel arrangements when services were affected for more than four hours on Saturday night.

The disruption stretched further yesterday, when services between Ang Mo Kio and Newton stations remained down before they were restored at 1.50pm.

In a statement yesterday, the Land Transport Authority (LTA) said preliminary investigations showed that water had entered the tunnels between Bishan and Braddell stations through a portal opening near Bishan MRT station - where above-ground rail tracks transit underground - after a torrential downpour on Saturday afternoon.

MRT tunnels are equipped with pumps, which are supposed to kick in when water enters.

Under normal circumstances, rainwater run-off accumulated in the adjacent storm water sump pit - a hole designed to collect water - would have been siphoned off by a system of pumps, said the LTA.

But on Saturday, the water pumping system did not work, causing rainwater to overflow from the storm water sump pit into the tunnel opening and accumulate at the lowest point of the Bishan and Braddell stretch of the tunnel.

SMRT immediately deactivated the trackside power supply as a safety measure, and the pump system has since been repaired.

Detailed investigations into the cause of the disruption are ongoing, said the LTA.

The disruption on Saturday was made worse by another incident - a trackside fire between Marina Bay and Raffles Place stations that later went out by itself.

The LTA said the fire was unrelated to the earlier incident, and it is investigating its cause.

National University of Singapore professor Lee Der Horng, who specialises in transportation systems, said the weekend disruption "could have been avoided".

He said the malfunction could be due to insufficient maintenance or testing of the water pumping system, adding: "SMRT should identify critical systems and should have redundancy in place, so if the first-line equipment fails for whatever reason, the backup system can just kick in."

Singapore Institute of Technology assistant professor Zhou Yi suggested that SMRT consider first installing back-up pumping systems at the transit areas between the underground and overground sections of the tunnel, subject to conditions and cost limits, to prevent similar incidents from occurring.

He added that the frequency of checks on the pumping and underground drainage systems may need to be stepped up during the rainy season.

"However, it is good to see that the buses were arranged effectively... It is also good to see the joint effort from various parties, including LTA, SMRT, PUB and the Singapore Civil Defence Force (SCDF)," he said.

Train operator SMRT, in an update on Facebook at 1.52pm yesterday, said the resumption of train services followed an "all-out, overnight effort" to clear water in the tunnels between Bishan and Braddell stations.

SMRT said it worked with teams from SCDF, national water agency PUB and LTA to pump out water from the tunnels, an operation that SCDF said was completed at around 11am yesterday.

Affected trackside equipment was inspected, cleaned, replaced and tested before passenger services resumed. Checks were also conducted on other tunnel portal pump systems located throughout the North-South and East-West lines, said the LTA.

When The Straits Times visited Bishan MRT station at around 7.30am yesterday, about 30 commuters were seen queueing for the bridging bus service at the bus stop outside the station. SMRT staff were present to guide them.

One of the commuters, Mr Alvin Chong, 53, had to take a bridging bus from Bishan to Newton.

Mr Chong, who is self-employed, had already been affected by the breakdown on Saturday while out with friends - he ended up taking a bus from Beach Road to Buona Vista.

"You get more frustrated as you experience more (of the disruptions)," he said.

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