More than 130 monitoring points along Hong Kong’s most expensive rail line have sunk to the point that further investigation is required, with the future Exhibition Centre station in Wan Chai being the most affected, the MTR Corporation revealed on Thursday.
This was the first comprehensive picture of subsidence problems made public by MTR Corp since it was hit by a series of construction scandals over the past months. But both the rail operator and the government played down safety concerns.
The troubled railway giant promised to change its protocol and suspend work as soon as any case of subsidence was deemed to reach “trigger value”, or a level requiring attention.
The MTR Corp submitted data from 1,482 monitoring points along the Sha Tin-Central rail link, parts of which are still under construction, to the city’s lawmakers on Thursday, ahead of a special meeting of the Legislative Council’s railways subcommittee on Friday.
The rail operator said it had installed “thousands” of monitoring points since construction on the HK$97.1 billion (US$12.4 billion) line started in 2012.
As work progressed, 1,482 points remained active, attached to buildings, roads and other public facilities such as water and gas pipes. The document submitted by the MTR Corp did not include the exact addresses of the monitoring points.
The data showed subsidence reaching the trigger values at 131 points near, or related to, eight out of 10 stations along the new line, which is due to start phased operations by the middle of next year.
“Exceeding the trigger values does not necessarily mean that nearby buildings, structures and facilities would become unsafe,” the MTR Corp said, adding that constant monitoring and remedial work would ensure their safety.
“Works [under the changed protocol] will only be resumed after new trigger values, or after sufficient protection measures have been implemented and agreement with relevant government departments and utility operators has been reached.”
The most affected station was Exhibition Centre, where 14 per cent, or 49 out of 355 points, reached or exceeded trigger values. None of the 49 points were attached to buildings, but one – a pavement – sank by 7.5cm.
Buildings Department guidelines call for action if land subsidence of more than 2.5cm is found.
Subsidence was also discovered at 23 out of 76 points near a tunnel connecting the Exhibition Centre and Admiralty stations.
Three buildings at the Fleet Arcade complex on Fenwick Pier Street on Hong Kong Island had sunk beyond the trigger values. The 14 points installed at the complex recorded an average subsidence of 3cm, and the MTR Corp said the affected buildings were tilting “within allowable levels”.
At To Kwa Wan station in Kowloon, the rail operator flagged 36 out of 248 points, including one attached to a building on Ma Tau Wai Road that sank by 6.1cm, while 13 other points subsided from 1.8cm to about 5cm. Five sections of gas pipes were also hit by subsidence.
The MTR Corp said additional water had been pumped under some of the buildings, and tilting levels in all the affected blocks were acceptable.
The company said the trigger values set for buildings in To Kwa Wan had been “revised” to 1.5cm-6.1cm, but gave no information on the original values.
The government, in a separate document sent to the subcommittee, said it had found no structural issues in the 18 buildings affected by subsidence.
“The Buildings Department also inspected relevant buildings nearby and no obvious structural problem was found,” it said of the Exhibition Centre area, where work has been suspended since August 10.
Structural engineer Ngai Hok-yan said the variation in trigger values set for buildings in To Kwa Wan showed signs of the railway firm “moving the goalposts” over the years.
“I believe the government would have asked the MTR Corp to tweak their designs before works started, to ensure they would not exceed the limit of 2.5cm,” Ngai said.
Lawmakers have previously questioned whether the rail firm has been changing the trigger values on its own.
But pro-establishment lawmaker Michael Tien Puk-sun, who chairs the railways subcommittee, said the MTR Corp was being honest by revealing it had exceeded revised trigger values at “many inspection points”.
The Democratic Party is set to move a non-binding motion at Friday’s meeting, calling for an investigation under Legco’s special powers.
“The MTR Corp said it would certify the safety of the buildings, but it’s actually the one causing all this; how can Hongkongers believe it?” party veteran Helena Wong Pik-wan said.
The construction scandals prompted the government to demand heads roll among those in charge of the troubled project earlier this month, while asking police to investigate “huge discrepancies” and “conflicting reports” about what went wrong.
Four senior managers left the company immediately while the CEO is due for early retirement.
This article MTR Corp admits subsidence at more than 130 locations along Hong Kong’s costliest rail line first appeared on South China Morning Post
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