ABSTRACT
The 50 m deep Bosphorus is an international waterway that connects the Black Sea to the Sea of Marmara, with the European side of Istanbul on one side, and the Asian side on the other (Figures 1 & 2). The existing rail systems on each side of the Bosphorus are to be upgraded to a commuter rail system connected by
a tunnel. While that tunnel descends through soft ground into rock each side of the Bosphorus, an immersed tunnel is used to traverse the very soft deposits beneath the Bosphorus and thereby to connect the two rock tunnels.
