Marmaray Project, is the suburban rail system connecting Istanbul Halkalı and Gebze.
The rail system that is going to connect European and Asian sides of Istanbul with a 1387 m long railway tunnel under the Bosporus is 76 km in total. This railway track will go into the underground tunnel at Yedikule, and thus proceed to Yenikapı and Sirkeci, pass the Istanbul Strait through the tube tunnel to arrive at Üsküdar Underground Station and continue in the underground tunnel until Söğütlüçeşme. The passage under the Bosporus is materialised by 11 tube elements of different lengths (98.5-138 m) that have been sunk and united. The underground tunnels of the project, just like the similar constructions in the world, are assumed to be considerably safe in the state of a possible earthquake.
