Signalling system blamed for HK MTR collision was also behind 2017 crash at Joo Koon station on Singapore MRT

19-Mar-2019 Intellasia | South China Morning Post | 6:00 AM Print This Post

The signalling system believed to be at fault for Monday morning’s MTR train collision was also behind a crash on Singapore’s network that injured 38 people.

Hong Kong Federation of Railway Trade Unions chair Lam Wai-keung said the trains had crashed while running the system, developed by French company Thales, known as SelTrac.

SelTrac, also known as communications-based train control (CBTC), was installed on Singapore’s East West MRT line. In late 2017, two trains collided at the line’s Joo Koon station while carrying passengers.

According to the Singaporean government’s Land Transport Authority, the collision was caused by a “software logic issue” that prevented communication between equipment on board the train and trackside.

Train crash may leave key link between Hong Kong stations closed until Tuesday

Thales was said to have fixed the issue in 2017.

Lam said the incident on Monday had not been the worst case scenario, as the trains were travelling at a low speed.

“The driver did what he should have, including trying to stop the train,” he said.

1. What is the MTR’s new signalling system? Who is the signalling system supplier?

In 2015, the MTR Corp spent HK$3.3 billion upgrading the signalling systems on seven lines, including the Tsuen Wan line, where the crash happened on Monday.

The other six lines are Island, Kwun Tong, Tseung Kwan O, Disney, Tung Chung and the Airport Express.

Existing signalling systems on the Kwun Tong and Tsuen Wan lines had been in used for decades since they opened in the late 1970s and 1980s.

As part of the Sha Tin to Central rail link project, the signalling system on the East Rail Line, which runs between Hung Hom in Kowloon and Lo Wu in the New Territories, was also to be replaced.

The upgrade on the Tsuen Wan Line was supposed to be completed late last year, while that on the East Rail Line was expected to be completed this year.

Thales, in a joint venture with fellow French company Alstom, were awarded the contract to resignal and upgrade the systems on seven lines.

Thales and Alstom are responsible for the replacement of the existing signalling system including Automatic Train Supervision (ATS), interlocking, and Automatic Train Control (ATC) in the control centre, trains and stations. Thales provides the SelTrac CBTC system.

A maintenance option is also included in the contract. The project will equip the seven MTR lines with the latest CBTC technology, safely adding capacity, reliability and maintainability on the existing infrastructure system.

The consortium says CBTC is the latest generation of technology for metro and suburban rail networks. It gives operators precise control in the movement of their trains, allowing them to run at higher frequencies and speeds in total safety – with or without drivers.

2. Is the SelTrac signalling system installed in train networks in other countries?

The system was also installed on Singapore’s East West MRT line.

On November 15, 2017, two trains collided at Joo Koon station while carrying passengers, injuring 38 people.

According to Thales’ official website, the London Underground is using SelTrac CBTC to modernise its signalling infrastructure on the Jubilee and Northern line upgrades.

3. What caused the accident in Singapore?

According to Singapore’s Land Transport Authority, the MRT was running both the old signalling system and SelTrac CBTC at the same time.

At the time of the incident, the train was travelling on tracks under SelTrac CBTC’s control.

A series of software faults meant that a safety feature, which ensures there is a sufficient distance between trains, was disabled, as the train moved onto tracks regulated by the older system.

Noticing the abnormality, the driver stopped the train at Joo Koon station to offload passengers, while another train stopped closely behind.

After the platform doors were closed, the second train moved forward and collided with the first, as it did not register the safety feature.

4. Where is the new signalling system being tested?

The system is currently being tested on the Tsuen Wan line, during non-operational hours, between 2am and 5am.

Lam said on Monday, that the crash happened during a test simulating services during peak hours, with trains travelling in close distances.

In addition to the driver, Lam said other employees are usually on board to record data for further analysis. He said no one else had been on board on Monday.

5. What are the differences between the new and old signalling systems?

The new system was supposed to help the MTR Corp increase train frequency and capacity, as well as reduce faults.

In a document provided to the Legislative Council in 2017, the railway firm said the new system was more reliable than the old one.

“Even if a component malfunctions, backup devices will ensure the signalling system continues to function properly,” it said of the new system.

The firm also said the new system had a similar number of parts as the one currently in use.

6. What other accidents have been related to the MTR’s signalling system?

In February this year, a train on the Tsuen Wan Line failed to stop correctly during a trial of the new signalling system. It was supposed to stop before turning back, but went slightly beyond the designated point, the firm said. The MTR said it was not an uncommon issue as the new system was being tested.

In October last year, four lines were hit by delays while running the current system.

The delays lasted more than six hours and the railway firm attributed it to a signalling fault.

A similar incident happened on the Kwun Tong Line in 2017, when trains had to be manually operated due to faults in communication equipment.

The delays lasted more than 10 hours and the railway firm was fined HK$2 million.


Category: Hong Kong

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