Hong Kong leader Carrie Lam Cheng Yuet-ngor has vowed to learn from the troubled construction of the city’s most expensive rail project, a key stretch of which is slated to open on Sunday after repeated delays and cost overruns.

At a ceremony on Saturday ahead of the full opening of the Tuen Ma line – whose Tai Wai-Hung Hom section comprises part of the HK$90.7 billion (US$11.7 billion) Sha Tin to Central link – Lam admitted the rail project had been beset by challenges over the years.

“The Hong Kong government, MTR Corporation and our construction teams have deemed every challenge a motivation for innovation. We have sought to resolve the problems facing us and also learn our lessons to ensure smooth sailing for future projects,” she said.

Sunday’s opening involves the stretch of the Tuen Ma line running from Kai Tak to Hung Hom.

The chief executive also pledged to make transport infrastructure the government’s top priority in an attempt to release more land along rail lines for housing projects and improve transport connections in the city, such as the Northern link.

Plagued by shoddy work and cover-ups, the construction of the Sha Tin to Central link by railway operator the MTR Corp and its contractors has been investigated on several occasions, including through a government-appointed commission of inquiry, a probe by an expert team of officials and an auditors’ review.

The Tuen Ma line will connect existing lines via new stations to become the city’s longest rail corridor, at 56km.

The first section of the 27-station line, connecting Wu Kai Sha and Kai Tak by way of Tai Wai, Hin Keng and Diamond Hill, opened in February last year.

Sunday’s opening involves the rest of the line, which runs from Kai Tak to Hung Hom – where it will connect with the former West Rail line – via Sung Wong Toi, To Kwa Wan and Ho Man Tin.

The line had been expected to open in mid-2019 after an earlier target of December 2018 was pushed back because of construction problems.

It was further delayed to this month to allow for reinforcement works at the scandal-hit Hung Hom station, where a whistle-blower revealed issues involving shoddy work.

More delays loom for the Sha Tin to Central link’s cross-harbour section between Hung Hom and Admiralty, which was already pushed back from the fourth quarter of 2021 to the first of 2022. Work on the section was affected by signalling system glitches for the connecting East Rail line in September last year.

The eight-car trains on the Tuen Ma line will run at three-minute intervals during the morning and evening peak hours, with journeys between To Kwa Wan and Central taking only 20 minutes and costing HK$12.50. A trip between Kai Tak and East Tsim Sha Tsui will take 13 minutes and cost HK$7, down from 32 minutes on the previous routing.