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 Asian 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; since February 2020, ₺36.40 (about $4 US) for cars and ₺54.70 ($6 US) for minibuses. In February 2021 the toll increased by 26% to ₺46 (approx. $6.20) and ₺69 (~$9.30) respectively. 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 (toll plaza, administrative units). 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. (ATAŞ) was founded on 26 October 2009