The project exemplifies the government's plan for infrastructure expansion. The special purpose vehicle (SPV) on the job is Avrasya Tüneli İşletme İnşaat ve Yatırım A.Ş. (ATAŞ), a joint venture of Yapı Merkezi from Turkey and SK E&C from Korea. The consortium will develop, build and operate the tunnel over 30 years.

The project-team roster comprises an impressive array of blue-chip international firms: U.S.-based Parsons Brinckerhoff, as lead designer; U.K.'s Arup, in charge of technical due dilligence; U.S.-based Jacobs and Arup, for traffic studies; Netherlands-based Fugro, for geotechnical studies; Germany's Herrenknecht, as TBM supplier; and French firm EGIS, for tunnel operations.

The lead re-insurers came from Munich, Zurich and Korea. The European Bank for Reconstruction and Development and the Investment Bank were involved with the financing, as were several private banks from Europe, Korea and Japan. Just after the tender was signed, the world was hit by the financial crisis of 2008, delaying the project from the start. It was not the only cause for delays, however.

"One of the issues was that the project had to complete some bureaucracy in Turkey so that we could sign the actual concession agreement," said Basar Arioglu, chairman of the board of ATAŞ. "It turned out to be a lengthy process."

The contract was signed in 2011, but it took until February 2013 to achieve the financial close. The one-year delay occurred because of legal issues between the Turkish treasury and the SPV's lenders, according to S.J. Seo, CEO and board member of ATAŞ.

The technical challenges of the project were significant: the twin-deck, 13.7-m-dia tunnel is being bored through hard rock on the European and Asian sides and in soft sea sediment, which means the TBM has to withstand an expected water pressure of 11 bars at its lowest point of 110 m. Furthermore, the project is located 15 km from the fault line: Earthquake is a major consideration, and in order to accommodate the differential movement between soft soils and hard rock during an earthquake, the team is placing two rubber-and-steel seismic joints capable of accommodating up to 7.5 centimeters of differential movement, according to Mustafa Tanriverdi, technical director of ATAŞ.

The team will start boring the tunnel in April and expects to finish in May 2015, after which the fireproofing, electrical and egress work will start. The tunnel is scheduled to open in mid-2016.