Tunnelling projects for MRT lines and expressways may become quieter and be completed in a shorter time in future, as their designers will soon be required to make them easier to build.
The Building and Construction Authority (BCA) said yesterday that it will extend a framework now used for high-rise buildings to include tunnelling projects.
Under the buildability framework, designers and developers must meet a minimum standard of labour-saving methods and technology or face penalties.
For example, they can use machines and prefabrication - where parts are made elsewhere and taken to the construction site to assemble - and reduce the excavation on site.
Of prefabrication, Deputy Prime Minister Tharman Shanmugaratnam said: "There's a lot of reduction of disamenities for the public because projects are completed faster, less noisily and with much less dust."
He added that BCA expects site productivity to grow yearly by more than 2 per cent over the next five years, beyond the annual growth of around 1.2 per cent over the past five years.
Mr Tharman, who is chairman of the National Productivity Council, yesterday visited the construction site of three new Nanyang Technological University residential halls, which are being built using a more efficient "prefabricated prefinished volumetric construction" (PPVC) method.
Whole rooms are made overseas, including interior fittings such as lights and fans, fitted out further in Singapore before they are taken to the construction site and stacked into a building. This "Lego-style" method saves up to 25 per cent to 40 per cent in labour and 15 per cent to 20 per cent in construction time.
While the method costs around 18 per cent more than the conventional concrete construction now, Mr Tharman said costs can be reduced as more suppliers come on board. "The public sector is taking the lead in building up demand," he said.
The process involves more high-tech jobs in manufacturing the rooms and fewer low-tech jobs on the construction site, he said. "We are going to be short of manpower for the long term. We want to offer higher quality jobs and this is the way to go."
BCA will have 10 integrated construction and prefabrication hubs by 2020, where PPVC modules can be made in Singapore.
Speaking about the new framework for tunnelling projects, BCA chief executive John Keung said civil engineering projects are expected to take up a larger portion of Singapore's construction demand in the future, up from around a quarter now.
"It's not a building, so you've got to find a different way to encourage them to make it easy to build," said Dr Keung, adding that BCA is working with the Land Transport Authority and other regulatory bodies to develop the framework.
The aim is to achieve 25 per cent to 40 per cent productivity improvements.
Civil engineering firm KTC Group's chief executive Rajan Krishnan welcomed the move to encourage prefabrication for tunnelling. Besides tunnel linings, which are already made off site, things such as track beds, drainage systems and walkways could be precast too, he said.
"The final cost remains to be seen, as it is a balance between labour, equipment and land space but it would be more productive and safer because you have fewer people and equipment working underground," he added.
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