Information published on 25 June 2010 in the UIC electronic newsletter "UIC eNews" Nr 192.

Marmaray Tunnel construction under the Bosphorus

Technical visit of the 6th UIC World Congress on Rail Security to the Marmaray Tunnel construction

Participants at the 6th UIC World Congress on Rail Security had the opportunity yesterday to visit Marmaray Tunnel, the undersea rail tunnel being constructed to link the European and Asian sections of Istanbul, running under the Bosphorus Strait. The idea of linking the two sides of Istanbul underwater was first dreamt of by Sultan Abdul Mecit 150 years ago.

When completed, it will be the world’s deepest undersea immersed tube tunnel dedicated to passenger traffic, and most probably freight traffic (the tunnel’s administrators hired consultants to study the options for allowing the tunnel to carry freight traffic). The name Marmaray (Marmarail) comes from combining the name of the Sea of Marmara, which lies just south of the project site, with ray, the Turkish word for rail.

The project includes a 13.6 km Bosphorus crossing and the upgrading of 63 km of suburban train lines to create a 76.3 km high-capacity line between Gebze and Halkali. The Bosphorus (Istanbul Strait) will be crossed by a 1.4 km-long earthquake-proof immersed tube. Construction of the Marmaray project started in May 2004. The Marmaray tunnel was completed on 23 September 2008 with a formal ceremony to mark the completion of the tunnel on 13 October. Completion of the entire project has been repeatedly delayed, and as of December 2009, was expected to occur in October 2013. After completion, Istanbul’s rail transportation usage is predicted to rise from 3.6% to 27.7%, which would see Istanbul’s percentage rate of rail transportation use as the third highest in the world, behind Tokyo (60%) and New York City (31%).

The Japan International Cooperation Agency (JICA) and the European Investment Bank have provided major financing towards the project. Since April 2006, JICA has lent 111 billion yen and EIB 1.05 billion euros. The Japanese partners are involved in the civil engineering and many international companies are dealing with equipment and engineering.

The total cost of the project is expected to be approximately 2.5 billion dollars. From late 2009, costs were expected to increase by approximately 500 million dollars due to the archaeological delays.

More information on this project will be published in a later edition of UIC eNews.