Eurasia Tunnel
The Eurasia Tunnel is a road tunnel in Istanbul, Turkey, crossing underneath the Bosphorus Strait. The tunnel was officially opened on 20 December 2016 and opened to traffic on 22 December 2016.
The double-deck tunnel connects Kumkapı on the European part and Koşuyolu, Kadıköy, on the Anatolian part of Istanbul with a route including the tunnel approach roads. It crosses the Bosphorus beneath the seabed at a maximum depth of −. It is about south of the undersea railway tunnel Marmaray, which was opened on 29 October 2013. The journey between the two continents takes about 5 minutes. Toll is collected in both directions. As of 16 August 2024, daytime tariff is ₺156 for cars, ₺234 for minibuses and ₺60.80 for motorcycles. A 50% discount is applied during nighttime hours.
Background
In 1891, French railway engineer Simon Préault presented a preliminary project for an underwater tubular bridge "patented by the Ottoman imperial government", consisting of a submerged bridge supporting a tube where steam trains would run.The conceptual background of Eurasia Tunnel reaches back to the findings of the 1997 Transportation Master Plan undertaken by Istanbul University on behalf of Istanbul Metropolitan Municipality. Based on this plan, a pre-feasibility study had been conducted in 2003 for a new Bosphorus crossing. According to the results of this study, a road tunnel was recommended as the solution that offered the highest degree of feasibility.
The Ministry of Transportation, Maritime and Communication of Turkey commissioned a feasibility study by Nippon Koei Co. Ltd. in 2005 to assess route alternatives for a new tunnel crossing. Based on environmental and social criteria, cost and risk factors, the study concluded by supporting the initially proposed route as the preferred option.
The three current bridges across the Bosphorus were taken into consideration in selecting the tunnel's location, which was put farther south to better balance the distribution of traffic between the crossings. Other selection criteria included the route's lower investment cost due to a shorter tunnel length and the availability of sufficient space for construction sites and operational buildings. High level assessments based on corridor alternatives that are comprehensively defined in the feasibility study also support the selection of the proposed route in terms of environmental and social costs and risk factors.
Investors
Avrasya Tüneli İşletme İnşaat ve Yatırım A.Ş. was founded on 26 October 2009 by the partnership of Yapı Merkezi from Turkey and SK E&C from South Korea.The build–operate–transfer model adopted at the Eurasia Tunnel, has brought together the private investment dynamism and their project experience, and the support of international financial institutions. The concession lasts 29 years. Partnership contract includes guaranteed minimum revenue and profit sharing for parts exceeding guaranteed revenue.
The European Bank for Reconstruction and Development is supplying a finance package worth US$150 million. Other components of the US$1.245 billion financing package include a $350 million loan from the European Investment Bank and financing and guarantees from Export-Import Bank of Korea and K-Sure, also with participation from Sumitomo Mitsui Banking Corporation, Standard Chartered, Mizuho Bank, Türkiye İş Bankası, Garanti Bank and Yapı ve Kredi Bankası. A hedging facility for the transaction is provided by some of the lenders as well as Deutsche Bank.
Project segments
The project consists of three main segments:;European side
Construction of five U-turns as underpasses and seven pedestrian crossings as overpasses along Kennedy Street that stretches between Kazlıçeşme and Sarayburnu as a shoreline road beside the Sea of Marmara. Widening of the entire Segment 1, which is approximately, from 3x2 lanes to 2x4 lanes.
;Bosphorus crossing
Construction of a, two-deck road tunnel with two lanes on each deck, a toll plaza and an administrative building on the western end and ventilation shafts on both ends of the tunnel.
;Asian side
Widening from 2x3 and 2x4 lanes to 2x4 and 2x5 lanes along an approximately stretch of the current D100 road that links at Göztepe to Ankara-İstanbul State Highway, and construction of 2 bridge intersections, 1 overpass and 3 pedestrian bridges.
Technical details
The American firm Parsons Brinckerhoff was responsible for the design, while the British Arup Group and American Jacobs Engineering Group undertook the technical and traffic studies and HNTB provided independent design verification. The geotechnical survey was by the Dutch consultancy Fugro. The tunnel boring machine was supplied by the German manufacturer Herrenknecht. The Italian company Italferr was in charge of works management and project review on behalf of Administration. The French company Egis Group will be in charge of the operation and maintenance.The TBM section crossing the Bosphorus is long while another is constructed by the New Austrian Tunnelling method and cut-and-cover method. The tunnel's excavation diameter is, which allows an inner diameter of with -thick lining.
The tunnel alignment is located in a seismically active region, about to the North Anatolian Fault Zone. To decrease the seismic stresses/strains below the permissible levels, two flexible seismic joints/segments; with displacement limits of ± for shear and ± for extraction/contraction; were innovated, designed specially, localized through geological/geophysical/geotechnical conditions, tested in laboratory; implemented 'first time' in TBM tunnelling under similar severe conditions. The design earthquake magnitude was specified as moment magnitude of 7.25 and design of functional and safety evaluation earthquakes have a return period of 500 and 2,500 years, respectively. Seismic joint locations defined during design phase were verified through continuous monitoring of cutterhead torques.
The tunnel was excavated and constructed with a diameter Mixshield Slurry TBM exclusively designed and equipped with the latest