Hong Kong Mass Transit Railway (MTR) has resumed testing of the signalling system on the East Rail Line during non-traffic hours.

The testing was suspended in March following a rare train collision during trials on the Tsuen Wan line.

Although the signalling systems on the two lines are different, MTR suspended all train tests relating to signalling systems to ensure safety and prevent incidents.

The tests restarted following a comprehensive safety review and a detailed assessment by the respective contractor.

An independent safety assessor appointed by MTR evaluated the signalling system and confirmed that it meets international safety standards for dynamic testing.

MTR operations director Adi Lau said: “Safety is of utmost importance to the corporation. Stringent and detailed review and investigation have been conducted during the past few months.

“We will continue to safeguard public safety, as well as the safety of our staff and contractors during the signalling replacement works.”

Testing on the signalling system will be conducted during non-traffic hours for two to three nights a week. MTR will monitor the trials throughout the testing period, as well as undertake necessary contingency measures to minimise any impact on regular services.

In March, two trains collided near Central station on the Tsuen Wan line during an overnight trial of the signalling system. No passengers were onboard during the incident.

However, the collision raised serious questions over the reliability of the new Thales-designed signalling system called SelTrac.

MTR said that a software issue in SelTrac may have been responsible for the crash, an allegation that Thales denied.