“We’ve been retesting the new system with the new trains for different scenarios,” he said. “During the process, we’ve discovered some problems with route-setting for the trains and we’ve decided to further improve the system. We don’t know how long it will take, but we hope to deliver a safe and reliable service to passengers.”

Chow admitted the work would further impact the opening of the cross-harbour section of the link between Hung Hom and Admiralty, which had already been delayed from the fourth quarter of 2021 to the first quarter of 2022.

“The improvement work will definitely impact the progress of the section between Hung Hom and Admiralty,” he said. “We are now making assessments and hope to reduce the impact to a minimal extent.”

Another MTR Corp source said that during a recent trial run, one of the new trains was mistakenly assigned to the wrong route.

“If a train is assigned a wrong route, it will go to a different destination. Normally it will affect the journey, but it won’t cause any safety issues,” the insider said.

“Since all the routes are assigned by the computer, the MTR needs to find out if there’s something wrong with the signalling system, or if it was caused by human error over wrong data entered.”

However, MTR Corp management stopped short of saying what caused the route-setting problems, or how serious they were.

Operations chief Sammy Wong Kwan-wai would only offer assurances that the issue would not affect safety, and that the East Rail line would maintain its normal services on Saturday.

“For this route-setting situation, it will not affect our automatic train projection system – trains will keep a safe distance between each other. Therefore, service safety will not be affected,” he said.

MTR Corporation seeks to allay fears of congestion over shorter train models

In a statement on Friday night, MTR Corp said that it had already been aware of the “route-setting situation”, having noticed it after they started testing the new system in May.

“This situation has not affected the operational safety of the railway system or the new signalling system … Our project team thinks we can better meet public expectations if we roll out the new train arrangement after conducting the enhancement work,” it said.

Civic Party lawmaker Jeremy Tam Man-ho, however, accused the operator of covering up the real problem, saying it was inevitable that the Sha Tin-Central link would be further delayed.

“Delays and cost-overruns are expected. I am very unhappy with the account given by the MTR Corp. They failed to tell us what exactly has happened with the new signalling system,” he said.

“When did it happen, who should be responsible and how will they rectify the problems? The MTR should have given us a detailed account.”

Hong Kong MTR shoddy-work scandal: Hung Hom station site safe, inquiry panel says

A May trial run of the signalling system on the East Rail line during off-hours saw the automatic train supervision system experience a blackout, the line’s interlocking system shut down and a test train run past a red signal. In a report submitted to the government in August, the rail giant said the incidents were all caused by human or procedural errors, and noted no one was injured and no facilities were damaged. It also pledged to enhance staff training and conduct new tests on the signalling system.

The Sha Tin to Central link, whose price tag has so far run to HK$90.7 billion (US$11.7 billion), has suffered repeated delays and cost overruns. The first part of the rail link – known as Tuen Ma line phase 1, connecting Wu Kai Sha to Kai Tak through Tai Wai, Hin Keng and Diamond Hill – opened on February 14.

The Tai Wai-Hung Hom section was initially expected to open in the middle of last year after an earlier target of December 2018 was pushed back due to construction problems. It was further delayed until late 2021 due to reinforcement work at Hung Hom station, where shoddy work was revealed by a whistle-blower.