International companies vying for the lucrative design-build contract to build the 32km long southern section of Sweden’s 190km long Bothnia high-speed rail line have until April to submit bids. The section includes 22km of tunnelling work (Oct 2002, p16).
The contract (with limited design freedom) involves construction of two major single tube tunnels between Offersjön and Bjällstaån. Firstly the 6km long, 70m2 Namntallhöjden tunnel, and secondly the 5.2km long, 70m2 Björnböleshöjden tunnel, both with parallel 25m2 service tunnels.
Construction will be by drill and blast through Sweden’s competent Gneiss.
Thorough pre-investigations by the client, Botniabanan, have indicated that the rock is of good quality with few significant problems envisaged. With an overburden maximum of 200m, the approximately 7.5m diameter running tunnel will be lined with a fibre re-inforced shotcrete lining ranging from 40mm to 100mm in thickness, depending on the rock Q values.
Having already received an internationally “positive response”, Kenneth Nordstrand, Civil works South project manager for the client told T&TI that the plan was to have a contractor on board by August this year with mobilisation work commencing in September. Although still speculative, early client estimates have put the cost of the contract in the region of US$118M.
The southern section is the first on the Bothnia Line to be let as an international tender with all of the project’s tunnels to the north currently being built by Scandanavian contractors.
The Bothnia Line includes 15 tunnels totalling 25km, costing some 20% of the US$1.2bn budget.
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