Causes for Joo Koon station, Hong Kong MTR incidents different

Initial reports indicate that the issue is linked to a software problem with the Tsuen Wan line's new signalling system.
Initial reports indicate that the issue is linked to a software problem with the Tsuen Wan line's new signalling system. PHOTO: HONG KONG MTR CORP

The Land Transport Authority (LTA) is concerned and is closely monitoring Hong Kong MTR's investigations into the collision of two Tsuen Wan line trains on March 18 (Safety under spotlight after trains collide in Hong Kong, March 19).

Initial reports indicate that the issue is linked to a software problem with the Tsuen Wan line's new signalling system.

While the developer of the SelTrac signalling system, Thales, also developed the new Communications-Based Train Control (CBTC) signalling system for Singapore's North-South and East-West lines (NSEWL), there are many versions of the SelTrac system.

No two CBTC systems are identical as they need to be custom-built. Each metro uses a unique system architecture, with software logic customised for the local environment and infrastructural conditions.

The SelTrac system itself is not new. It has been in existence for many decades and has been adapted for 86 metros in 40 different countries, including multiple lines in London, Shanghai, Dubai, Toronto and Vancouver.

Based on preliminary information, the causes and conditions that led to the Joo Koon station incident in late 2017 are completely different from what happened in Hong Kong this week.

What we faced was due to interface issues between the NSEWL's legacy and new signalling systems.

Immediately after the incident, LTA and SMRT delinked operations between the two systems to decisively remove this risk.

LTA also invited Thales to set up a CBTC simulation laboratory in Singapore - the first of its kind in Asia.

This has allowed LTA and SMRT, since April last year, to perform additional tests to fine-tune the new signalling systems' software and hardware before it is implemented on our rail lines.

The NSEWL has seen an improvement in mean kilometres between failure from 115,000 train-km in 2017 to 556,000 train-km last year.

The NSEWL has been operating entirely on the new CBTC signalling system since May last year.

Chua Chong Kheng

Deputy Chief Executive, Infrastructure and Development

Land Transport Authority

A version of this article appeared in the print edition of The Straits Times on March 20, 2019, with the headline 'Causes for Joo Koon station, Hong Kong MTR incidents different'. Print Edition | Subscribe