Turkey Bridge Spans Seismically Active Bay
A six-firm consortium now is assembling loans for a $6.5-billion project to build a 377-kilometer-long, privately financed toll highway in Turkey. The project—from Gebze, near Istanbul, to Izmir—includes a suspension bridge that likely will incorporate the world’s second-longest span over the seismically active Izmit Bay.
The Izmit bay crossing, with a 1,700 m span, “is still in the conceptual design stage,” says Simon Bourne, head of bridges at U.K.-based URS/Scott Wilson Ltd., Basingstoke. The firm, in a joint venture with AECOM, has a $15.9-million contract with the project consortium to supervise the bridge’s design and construction.
The consortium Otoyol Yatirims ve Isletme A.S. late this September signed a build-operate-transfer contract for the Gebze-Izmir highway with Turkey’s transportation ministry. The contract, expected to last 22 years, includes responsibility for operating and maintaining the highways and bridge.
Italy’s Astaldi S.p.A., based in Rome, is the only foreign member in the otherwise all-Turkish consortium. Local members are the Ankara-based contractors Nurol Insaat ve Ticaret A.S., �zalt?n Insaat ve Ticaret A.S., Yüksel Insaat A.S. and Gö�ay Insaat A.S. Makyol Insaat Sanayi Turizm ve Ticaret A.S., Istanbul, also is included.
The project will run along the Sea of Marmara’s northern shore to Izmir on the Aegean coast. In addition to the 377-km, six-lane highway, the project includes 44 km of connecting roads and the 3-km bridge with a 35.5-meter-wide orthotropic steel deck.
The project is slated to build over 18 km of viaducts, roughly 7.4 km of tunnels and 18 toll plazas. One of the key challenges facing the turnkey contractor is the bridge’s stability. The bridge will straddle the North Anatolian Fault, which shifted in 1999, devastating Izmit and surrounding areas.
In an effort to collect early insights into ground conditions at the bridge, the consortium last December awarded a $16.6-million site investigation contract to Netherlands-based Fugro B.V., Leidschendam.
The project is widely expected to start next year and last seven years. However, construction will begin only after the financing is fully in place, say officials at the General Directorate of Highways. The official financial launch will not be for another few months as the structure has not yet been finalized, adds one banker involved with the deal.
The consortium is required by the contract to put in 20% of the project’s financing as equity, with the balance in loans. In March, the joint venture mandated a group of Turkish, Italian and U.S. banks to structure the financial package. Project debt is expected to include commercial and multilateral loans with export credit guarantee agencies’ backing.
The consortium is expected to recoup its investment and operating costs with toll revenues, which it forecasts will generate $23 billion over the full concession period covered in the contract. The government has guaranteed revenues from a minimum traffic volume of 40,000 vehicles a day on the Gebze-Orhangazi stretch and of 35,000 vehicles a day on the Orhangazi-Bursa portion of highway.
The project revives earlier plans for the Izmit Bay bridge, won as a BOT contract by the Anglo Japanese Turkish Consortium in 1997. However, that contract was canceled when the consortium leader, Norway’s Kvaerner A/S, underwent a major restructuring. When completed, the project will more than halve to four hours the journey time between Istanbul and Izmir.