The Great Istanbul Tunnel is a three-storey, mixed tunnel project that will provide road and rail transportation between the Asian and European sides of Istanbul by passing under the Bosphorus Strait. The 3-Storey Grand Istanbul Tunnel, which will contribute significantly to the traffic of Istanbul, turkey’s most populous city, is the world’s first 3-storey tunnel. With the project, the bosphorus will be crossed at once, saving thousands of meters of tunnel construction costs and time. In addition, the metro tunnel needed by the July 15 Martyrs Bridge axis and the road tunnel needed by the FSM Bridge axis will be combined and crossed with a single tunnel. It is of great importance in terms of jointly providing road and metro transportation.
The project was announced on February 27, 2015. The tunnel, which will be built 110 meters below the strait, will be three storeys. The cost of the tunnel, which is scheduled to be completed within five years, is $3.5 Billion. Its length is projected to be 6.5 kilometres.
Tender preparation works are underway for the Great Istanbul Tunnel project. In the Great Istanbul Tunnel project, the main tunnel is planned to start at the Hasdal junction on the European Side, pass 140 meters below the strait and extend from the bottom of Beykoz Küçüksu on the Anatolian Side to the Çamlik junction. The tunnel will be connected to them from there.
Once operational, the tunnel will connect 11 rail lines and integrate with Marmaray. In the Great Istanbul Tunnel project, the rail system starting from Bakırköy Incirli will come to Mecidiyeköy and Zincirlikuyu and connect to the main tunnel. The metro, which passes under the sea to the Anatolian Side, will continue until Willows. While it is learned that the Gayrettepe-Istanbul New Airport and Halkalı-Istanbul New Airport metro lines are fully integrated into the 3-Storey Grand Istanbul Tunnel at Gayrettepe station and the Altunizade-Sabiha Gokcen metro line at Altunizade station, passengers will be able to reach Istanbul New Airport directly from Sabiha Gokcen Airport without landing at any station.