Cowi awarded Singapore subway design contract


Japanese contractor Nishimatsu Construction has hired consultancy group Cowi to help with tunnel design for Singapore’s Cross Island Line.

Cowi has won a work package that includes 2.9km of bored tunnels and 300m of cut-and-cover tunnels in phase one of the Cross Island Line underground mass transit system.

It also includes a two-story operations building with a five-story basement for electrical and mechanical services.

One of the largest tunnel boring machines operating in Singapore, measuring 12.6m in diameter, will be used to bore the only dual track tunnel between Tampines North and Defu stations. The depth of the drilled tunnel varied from nearly 50m underground at the deepest to less than 12m overburden at the shallowest. The cut and cover adits will again extend to a depth of 45m.

Cowi will work on the design in collaboration with its client Nishimatsu Construction.

Singapore’s Land Transport Authority awarded Nishimatsu a S$446m (£251m) civil contract for this part of the project last year.

Jotham Vizard, Senior Vice President of International Transportation Unit at COWI, said: “We are very proud to support Nishimatsu in building this state-of-the-art subway in Singapore. As TBM technology improves, large diameter tunnels are becoming more common and this project maintains our leading position in the large diameter market.”

Vince Goh, Managing Director of Cowi Singapore added: “This project poses a number of exciting engineering challenges in addition to the large diameter tunnel. Among other things, the tunnel will pass under a military airport with delicate fiber-reinforced pipes, runways, taxiways, aprons and airport structures that will further restrict ground movements during both drilling and mine construction.

“Additionally, any TBM cutter deployment under the airbase must be pre-planned and, due to the depth, occur in a hyperbaric environment. Multiple closely spaced adits for future underground infrastructure are also part of the challenge. The tunnel will also pass under public roads and will pass under the Sungei Serangoon Vehicle Bridge and the Kallang-Paya Lebar Expressway viaduct.

Construction is expected to start in June of this year.

Expected to open in 2030, the Cross Island Line will be Singapore’s longest fully underground line at more than 50km. It is expected to carry more than 600,000 commuters daily.

When completed, the line will facilitate travel through the eastern and western parts of Singapore and reduce congestion on the existing east-west line.


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