NO CAUSE FOR ALARM: The LTA and contractor Sembawang said there is no cause for alarm from the ground movement at Telok Blangah. -- ST PHOTO: DESMOND LIM
ALL tunnelling works on the Circle Line worksite near Telok Blangah have been halted, after part of the road sank four days ago.
The Building and Construction Authority (BCA) issued the order and revoked the contractor's tunnelling permit after a 7m stretch of two lanes sank about 20cm, close to the junction of Telok Blangah Road and Alexandra Road on Saturday evening.
The BCA said the stop-work order 'allows the Land Transport Authority to carry out investigations and take precautionary measures to ensure safety of workers and the public'.
Tunnelling work will not resume until the BCA is satisfied all is safe.
The stop-work order at the Telok Blangah site is the fourth this year on the $6.7 billion Circle Line project.
Last year, BCA stepped in three times to halt work, it told The Straits Times.
'For the Circle Line projects, the stop-work orders were mainly issued for tunnelling works when ground movements are more than what is predicted,' said the BCA spokesman.
The Straits Times understands that over the past four months, there have been two other instances when ground settlement resulted in craters measuring 8 to 10m.
Both were at the same Circle Line worksite where the future One North Station will connect to the Buona Vista interchange.
As for the problems at the Telok Blangah site, both the Land Transport Authority (LTA) and the contractor, SembCorp Engineers & Constructors, said there is no cause for alarm.
'Ground settlement is a natural occurrence close to excavation sites and above tunnels. It will not pose danger to the public as long as the settlement is within pre-
determined levels,' said LTA spokesman Naleeza Ebrahim.
An extensive array of instruments monitor the impact of construction works on structures in the vicinity of the worksite, she added.
Readings, designs and construction methods are also checked and reviewed regularly by the LTA and independent engineers to ensure the structures are safe.
In the case of Telok Blangah Road, Ms Naleeza added that the LTA had anticipated the problem and taken additional precautions by temporarily diverting traffic away from the site.
Also confident that the problem had been licked was Semb Corp.
Company spokesman Khoo Khim Seng said: 'There is no likelihood of further sinkholes because we have taken all the necessary precautions.'
SembCorp was awarded the contract worth more than $335 million three years ago, mainly to build the new orbital line's West Coast, Pasir Panjang, Alexandra and Telok Blangah stations.
The stations will form the 17km western arc of the 33km Circle Line. When completed in 2010, it will have 13 stations, with provision made for an extra three to be built later.
Work on all construction projects are subject to more stringent safety standards since tunnelling work at the Nicoll Highway stretch of the Circle Line collapsed three years ago, killing four workers.
Professor Leung Chun Fai, from the National University of Singapore department of civil engineering, said the sinkhole at Telok Blangah, although not major, is a warning sign.
'The authorities and contractors should take action before a major incident occurs,' he warned.
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