“Railway Bosphorus Tube Crossing (Marmaray) Project” is planned to provide an uninterrupted mass transportation system by integrating the upgraded commuter rails on European and Asian Coasts of Istanbul with a tube tunnel under the Bosphorus. The project covers the deepest immersed tunnel of the world with 58 meters. It has the total length of 76.3 km where almost 1,400 meters as immersed tube tunnel.

System will be established by; add of a third line to existing double track commuter rails on Europe and Asia sides, rehabilitation of tracks, infrastructure, stations, electromechanical systems, and new vehicles already procured. One track will serve for intercity passenger and cargo trains while the others as high standard commuter rails.