A joint venture between the Japanese firms Taisei Corp and Kumagai Gumi, with Turkish contractors Gama Endustri and Nurol Insaat has been awarded the $832M contract to construct the Bosphorous Strait rail tunnel connecting the European and Asian sides of Istanbul (T&TI, July 2003).
The JV beat off competition in the final round from one other Turkish-Japanese consortium consisting of Obayashi Corp from Japan, with the Turkish companies Yapi Merkezi, Kiska Insaat and Metis Insaat. Initially three JV’s submitted preliminary bids to the Turkish Transport Ministry but one was reportedly rejected for technical reasons.
In August 2003, a fourth consortium of Kajima, Nishimatsu and Mistubishi Heavy Industries with Turkish partners Enka Insaat and Dogus Insaat allegedly withdrew from bidding as the contract conditions were said to be difficult to fulfil.
The Marmaray Project is a 76km long upgrade to the rail link across Istanbul, of which 1.8km is an immersed tube tunnel across the Bosphorous River and 11km are running tunnels to be excavated by TBM and cut and cover. The tunnel phase of the project is being financed by the Japan Bank for International Cooperation (JBIC). The second phase, linking the tunnel to existing rail lines is expected to cost US$700M.
