Signal fault to blame for Joo Koon MRT collisionStalled train hit by another train at Joo Koon after software glitch; 29 injuredBy Maria Almenoar,
Assistant News Editor and Adrian Lim,
Transport Correspondent, The Straits Times, 16 Nov 2017An unprecedented software glitch in the signalling system of the East-West Line resulted in a stalled MRT train being hit from behind by another one at Joo Koon station yesterday morning.
This resulted in injuries to 29 people, three of whom were still in hospital yesterday evening.
The collision took place at 8.20am during the morning peak hour and disrupted train services between Boon Lay and Tuas Link stations through the day.
Train services between Joo Koon and Tuas Link stations will remain suspended today while the authorities carry out their investigations. Bus bridging services will be provided to the affected passengers. Other trains on the East-West Line will run at slower intervals.
In the accident yesterday, the first train had pulled into Joo Koon station when it stalled because of an anomaly in the signalling system, and its passengers were offloaded, save for a solitary SMRT staff member who remained on board.
The second train, which had stopped more than 10m behind and was carrying more than 500 passengers, unexpectedly lurched forward and collided with the first train.
At a press conference later in the day, Land Transport Authority (LTA) and SMRT officials explained that the signalling system had mistakenly profiled the stalled train as a three-car train, instead of the six-car train that it really was.As a result, the second train which had stopped 10.7m behind the first "misjudged the distance" between the two, resulting in a collision. Sharing their preliminary findings yesterday, SMRT and LTA said the first train departed Ulu Pandan depot with a software protection feature, but this was "inadvertently removed" when it passed a faulty signalling circuit.
Passengers got off the stalled train and the second one halted at the correct, safe stopping distance behind it. However, the second train moved forward a minute later when it could not properly detect the stalled train as having six cars.
Mr Alexandru Robu, 35, who was in the second train, described how it came to a sudden halt after its impact with the first one, causing passengers to lose their balance and fall. "I have experienced sudden stops before on the MRT, but this time, it was really bad," said Mr Robu, a service coordinator.
One MRT employee on each train and 27 commuters were hurt. Several were taken to hospitals, and most were discharged with minor injuries. The remaining passengers were taken off the train through the driver's cabin at the front - a process that took some time.
Thales, the firm supplying the new signalling system for the North-South and East-West lines, said it had never encountered a glitch similar to yesterday's before.
Mr Khaw said after the press conference: "Thales is confident of their system, but I advised the team, let's play doubly safe, where safety is involved, that is why I want them to suspend the Tuas West Extension tomorrow, so we have a whole day to do a thorough check before we resume the Tuas West Extension."
Asked if a committee of inquiry will be convened to look into this, Mr Khaw said the investigation should be allowed to take its course.On whether commuters' confidence in the MRT system had been undermined following yesterday's accident and last month's MRT tunnel flooding, Mr Khaw said: "Obviously people will be upset... I am equally upset."
Additional reporting by Christopher Tan and Tan Tam Mei
Joo Koon collision: 'It happened so quickly... It was a really big stop'Sudden impact threw many off balance; one door later opened to let passengers leave trainBy Aw Cheng Wei, Tan Tam Mei and Adrian Lim,
Transport Correspondent,
The Straits Times, 16 Nov 2017
Service coordinator Alexandru Robu, 35, was on his way to work yesterday morning when the train he was on collided with a stationary one in front of it at 8.20am.
"It happened so quickly," said Mr Robu, who was standing in the carriage closest to the collision. "It was a really big stop, and we heard a loud sound."
The sudden stop threw him off balance. He tried to break his fall with his hand and landed on the ground. He estimated that 30 people around him also fell.
"Some people fell on top of each other," said Mr Robu, who is from Moldova in eastern Europe. "Everyone took about one to two minutes to recover."
An announcement then came on informing commuters that help would be arriving in about 20 minutes. The plan was to tow the stationary train away before the second train could pull into the platform.
It was then that Mr Robu noticed a man on the ground holding his head.
"He did not look good," said Mr Robu. He went over to the man, who started to look unresponsive.
He said: "I tried to keep him engaged by talking to him and making sure that he was okay."
At this time, some people in the train were calling for an ambulance. Mr Robu pressed the emergency button to ask the driver if the first door could be opened to let the man out for fresh air.
It was starting to get stuffy in the train. "There was no air-con," Mr Robu said. "People were also getting anxious."
About 20 minutes later, a second announcement came on to inform passengers that the first door would be opened to let them out.
People left in a proper fashion, guided by SMRT staff and police officers. Mr Robu stayed with the injured man, who was put in a wheelchair once he got out of the train, and made sure he received medical attention.
Mr Samuel Ng, 48, a sports adviser who was getting off another train at about 8.50am, said that he saw people queueing to get out of the second train.He said: "There was no chaos, no shouting. When I went downstairs, there was also a very long queue at the control station."
Commuters on the platform said that they heard a dull thud before people started screaming.
Mr Ganeshan Sivalingam, 38, who was waiting at the platform for the train to Tuas Link, said he heard a "bang".
When he went closer, he saw that the blocks of metal at the front of the second train had hit the rear of the stationary train.
Station operators then ushered him and other commuters out of the station, where he got on a bus to work. He said that the train station was "not very crowded", and it took about five minutes for him to leave the station.
Parts of the platform had been cordoned off when Mr Robu left the train. Ground control staff from SMRT, and officers from the Singapore Civil Defence Force and the police directed commuters to leave the train station.
The platform reopened at about 11.20am, and trains were running on only one side of the tracks.
When reporters went to the National University Hospital and Ng Teng Fong General Hospital (NTFGH) in the early afternoon, the injured passengers were already being treated.
The Straits Times understands that some had already been discharged at that time.
Businessman Lim Kim Hock, 56, who runs a switchboard company, sent one of his workers, Mr Tan Ban Heng, 37, to NTFGH when he saw that Mr Tan's kneecap had become bloody and swollen.
Mr Lim said he wanted to see Mr Tan's injuries when he found out that he was in the accident.
He said Mr Tan had earlier declined medical help because the injury "did not look that bad". Mr Lim said: "Once I saw the injury, I told him he must go to hospital."
SMRT staff to help with compensation queriesBy Maria Almenoar,
Assistant News Editor,
The Straits Times, 16 Nov 2017
Passengers who were injured in the Joo Koon station train collision may approach staff at any SMRT station to ask about compensation.
Train operator SMRT said it would help any passengers affected even if they were not taken to the hospital immediately by its team.
SMRT said that at about 7.30pm yesterday, Ng Teng Fong General Hospital had admitted an injured passenger as a walk-in patient.
This brought the total number of injured to 29, including two SMRT employees.
The injured were treated at Ng Teng Fong General Hospital, where two remain warded for observation, and National University Hospital, where one passenger is still warded.
All injured passengers were on board the same train which had collided with a stationary train. The moving train was carrying 517 people, including its driver.
The injuries included bruises and fractures, with one passenger hitting the grabhold when the train lurched forward. One commuter broke a tooth, while another fainted during the incident.
An assistant station manager, who was on board the stationary train, was also injured after helping passengers alight.
The Ministry of Transport, Land Transport Authority and SMRT said they were in touch with injured passengers to offer them necessary assistance.
Joo Koon collision: 'Inadvertent removal' of software fix led to collisionLTA investigating why this happened, together with SMRT and firm supplying signal systemBy Adrian Lim,
Transport Correspondent,
The Straits Times, 16 Nov 2017
Software meant to fix a known problem in the East-West Line's new signalling system had been "inadvertently removed" and this led to the collision between two trains at Joo Koon station yesterday morning.
Sharing these details at a press conference 10 hours after the incident, the Land Transport Authority's (LTA) deputy chief executive Chua Chong Kheng said that it is investigating why this happened, together with operator SMRT and Thales, the French company supplying the signalling system.
Also present were Transport Minister Khaw Boon Wan, SMRT chairman Seah Moon Ming and SMRT group chief executive Desmond Kuek, but they were not part of the panel leading the press conference.
Mr Chua, who chaired the press conference, together with SMRT and Thales officials, revealed that earlier tests uncovered how an interruption in communications between onboard computers on a train would result in it being wrongly identified as a three-car train, rather than one with six cars.
To fix this on the East-West Line's new signalling system - which is used on the Tuas West Extension that opened in June - a software protection module was developed by Thales.
However, when a train passed by a faulty track circuit yesterday, this software module was "inadvertently removed". This caused it to be identified as a shorter, three-car train. This subsequently led to an-other train behind "misjudging the distance" to the one in front, causing the collision, in which 27 commuters and two SMRT staff were injured.
Thales, which has installed signalling systems for metros in cities such as Hong Kong and Vancouver, described the glitch as unprecedented.
Mr Chua also said the same type of signalling system, which has been implemented on the North-South Line this year, has "proven to be working very well".
While the Tuas West Extension - a four-station, 7.5km-stretch that extends from Joo Koon station - is using Thales' new signalling system, the rest of the East-West Line is on an older 30-year-old system.
"We are in a stage where we are going through a transition of trying to implement the new signalling system... this (faulty) signalling circuit, as we understand from Thales, was going through the process of being changed," Mr Chua said.
He added that it was "too early" to say whether yesterday's glitch will derail original plans to switch the rest of the East-West Line to the new signalling system before the end of the year.
The new signalling system allows trains to arrive at up to 100-second intervals, instead of the current 120 seconds.
Yesterday's collision occurred as the first train was about to move off from Joo Koon station. Before that, it had stopped there to offload all passengers, due to a separate signalling problem.
While the train and platform screen doors were opened for passengers to get off, the signalling system would prevent another train from pulling into the station and hitting it, said Mr Chua. The second train initially stopped about 10.7m - the correct safety distance - behind the first.
Experts said yesterday's accident was a worrying one.
Assistant Professor Andrew Ng from the Singapore Institute of Technology's (SIT) engineering cluster said that if the trains were moving on the tracks, and the front one was mistaken as a three-car train, the rear one could misjudge the distance, potentially leading to a collision.
Assistant Professor Zhou Yi, also from SIT, said that suspending operations on the Tuas West Extension today is a good move and puts the safety of commuters first.
"We need to be very cautious moving ahead," Prof Zhou said, adding that SMRT and LTA should request for Thales to further open up its systems for a better understanding.
Mr Ang Hin Kee, deputy chairman of the Government Parliamentary Committee for Transport and an MP for Ang Mo Kio GRC, said it was "important to quickly identify the cause of the collision and to provide assurance to all commuters that the matter is being addressed".
MRT collision: No train service on Thursday (Nov 16) between Joo Koon and Tuas LinkBy Maria Almenoar,
Assistant News Editor, The Straits Times, 16 Nov 2017
Train service between Joo Koon and Tuas Link stations was suspended on Thursday (Nov 16) for the authorities to carry out investigations, after two trains collided on Wednesday.
Bus bridging services were provided for affected passengers.
Commuters should also expect trains on the North-South and East-West lines to arrive at slower intervals, the authorities said on Wednesday.
The current two-minute interval between trains will be slowed down to between 2½ minutes and three minutes.
The Land Transport Authority (LTA) said that this was being done as an interim safety precaution after Wednesday morning's collision, which left at least 29 people injured.
"We want to make sure we understand fully what the cause is and that we have the right measures in place. Once we know that, we will be able to revert back to the previous... operations," LTA's deputy chief executive for infrastructure and development Chua Chong Kheng said at a press conference.
In a tweet at 4.43am on Thursday morning, SMRT said free bus services were available between Joo Koon and Tuas Link stations. It also said that trains were running as per normal on the North South Line.
Investigations so far found that a glitch in the new communications-based train control system wiped out a safety software feature when the first train passed a faulty circuit.
The French firm which provided the signalling system, Thales, said that this was the first time such an incident had happened.
"In fact, the CBTC (communications-based train control) is on record as one of the safest systems. We have never actually had a collision," said Thales representative Peter Tawn.
He added that it was unlikely, but the company has not ruled out increasing the safety factor - or the buffer distance - between trains, and a decision would be made once the investigations are completed. The current safety factor ranges from about 10m to 50m, and is calculated based on a number of parameters, including the gradient of the track, Mr Tawn explained.
In Wednesday's incident, the trains had adhered to the safety buffer of 10.7m before the train at the back lurched forward and collided with the one at the station platform.
SMRT's senior vice-president of rail operations for the North-South and East-West lines, Mr Alvin Kek, said that the operator was putting "additional checks and controls in place" as a safety precaution.
"We have told train captains to be a lot more vigilant... even if (the train is) driven in the automatic mode," he added, saying that drivers are trained to deal with such emergencies.
Additional information will also be made available to drivers in their train cabins to help them assess such situations better.
LTA added that trains will also go through an additional layer of control measures and manual checks before they are deployed.
Joo Koon collision: Signal failure hits confidenceBy Christopher Tan,
Senior Transport Correspondent,
The Straits Times, 16 Nov 2017
The word "ponding" comes to mind. It was used by national water agency PUB to describe massive floods which hit Singapore in December 2011.
Dr Vivian Balakrishnan, then Minister for the Environment and Water Resources, took issue with that in Parliament the following month.
"PUB should not have used the word 'ponding'. As far as I am concerned, I call a spade a spade. A flood is a flood," he said, echoing public sentiment.
The Land Transport Authority (LTA) and rail operator SMRT described yesterday's collision between two trains in Joo Koon station as an incident where one train had "come into contact" with another train, which conjures the imagery of a nudge.
SMRT repeated the same phrase on its Facebook page.
"This morning at 8.18am, a train heading in the direction of Tuas Link station stalled at Joo Koon station. At 8.19am, a second train stopped behind the first faulty train. At 8.20am, the second train moved forward unexpectedly, and came into contact with the first train."
It was only at 7.42pm that an updated statement by the LTA described the incident as a "collision".
Their earlier reluctance to call a spade a spade severely underplays the seriousness of an accident which left 29 people with injuries.
First and foremost, trains are not supposed to collide, or even come into contact with each other (unless one train was used to push out another disabled one, as has often been the case lately). That is what the signalling system is for. It keeps a safe distance between trains, acting like an invisible, impenetrable barrier between locomotives.
No metro system can operate without a reliable signalling system, which is actually the eyes of the network.
This is why when trains sense there is something amiss with the signalling system, or there is some interference, they will activate their emergency brakes. It is safety protocol - to be safe first rather than sorry later.
Usually, a train cannot pull into a station when the one in front of it has not left the station. This is why trains sometimes stop in the middle of a tunnel, and passengers are left wondering why. More often than not, it is precisely because the train in front has stopped for too long. So, instead of breaching the invisible barrier, the second train has to stop too, even if it is in the middle of nowhere.
That a train has somehow managed to breach this safety barrier is worrying, to say the least. At Joo Koon, trains switch over from the old fixed block signalling system to the new moving block system.
Investigations have uncovered that the glitch which caused the collision yesterday lies with the new system.
The new signalling system has been having numerous technical issues here, but none compromising safety until yesterday.
So, it is regrettable indeed that SMRT and the LTA have chosen such a light term earlier in the day to describe the incident. Like the tunnel flooding which took place just last month, it is not trivial. A signalling failure can have grave consequences. You do not need to have a vivid imagination to think of what might have happened if either train had more passengers. And if a "coming into contact" nudge can result in 29 people getting hurt, think of what a high-speed collision would entail.
In the 30-year history of Singapore's MRT system, there has been only one other train collision which resulted in injury. In 1993, one train ran into another at Clementi station, resulting in more than 150 people getting hurt. The incident triggered a public inquiry, which found that an oil spill on the tracks had compromised the stopping ability of the second train. It was not a signalling issue.
SMRT and LTA have to come out with full transparency on how yesterday's incident happened, and what concrete steps are to be taken to prevent a recurrence. And herein lies the rub: How does seeking to minimise yesterday's incident help reassure a public whose confidence has been shaken repeatedly since 2011 that the issues are being put right?
A sagging power-supply rail brought the North-South Line to a standstill on the evening of Dec 15 that year, and then again on the morning of Dec 17, as SMRT failed to detect and rectify the damage completely. Affecting more than 250,000 commuters, it was the biggest disruption then.
Another public inquiry was convened, and SMRT reshuffled its top management.
A power-supply trip caused both the North-South and East-West lines to fail on July 7, 2015, affecting about half a million commuters, the highest number on record here as of now. The LTA said a salt-caked insulator near Tanjong Pagar station was the cause.
A power trip at one of the network's substations caused the western sector of the North-South and East-West lines, parts of the Circle Line, as well as the Bukit Panjang LRT system to fail on April 25 last year. The unprecedented four-line disruption was suspected to have been caused by cable works on the East-West Line's Tuas West extension.
On March 22 last year, two SMRT trainee technicians were killed on the tracks near Pasir Ris station. Investigators found that a slew of standard operating procedures had been breached. The Manpower Ministry said SMRT had been flouting such guidelines since 2002.
On Oct 7 this year, tunnels between Braddell and Bishan stations were flooded, with water reaching waist level at some points. While preliminary investigations found that the crew in charge of maintaining the flood-prevention system at Bishan had not been doing their job properly and had in fact falsified work logs, the various individual key components such as pumps and switches were found to be in proper working order.
Even as Singaporeans were coming to terms with the flooding, yesterday's train collision took place.
Clearly, enough is enough.