Marmaray: Asia-Europe Tunnel
Just a pointer to a fascinating project that recently achieved a major milestone: the underwater tunnel of the Marmaray project, connecting the European and Asian sides of Istanbul, was completed on October 20th:
This is an immense engineering feat, since (in the words of one of the managers) "I can't think of any challenge this project lacks". Istanbul is an earthquake zone, the Bosphorus is one of the world's busiest shipping lanes, the excavation continually runs into historical ruins, and Turkey is not one of the world's stablest countries politically or economically. Once up and running in 2012, this will provide both commuter services across Istanbul (which are currently limited only to ferries) and allow through service for long-distance trains from Europe through to mainland Turkey.
Wikipedia has a fairly good article, plus a good map showing how radically transport will change once Marmaray and a few other metro projects are ready, all projected for 2012:
But the official site has not been updated since 2005...
As I had seen a documentary about this project some months ago - an interesting fact on this tunnel is that it is in fact not a tunnel in the normal sense, that means a hole drilled through the soil or bedrock. Instead they descended pre-constructed concrete structures onto the seafloor and connected them there.
Originally Posted by jpatokal
No where close to making the longest list but a significant railway tunnel opened in Istanbul last week providing both the symbolic and physical link between Asia and Europe.
Marmaray tunnel opens to link Europe with Asia, Railway Gazette, 29 Oct 2013
TURKEY: 'This project that was dreamed of 153 years ago, has been realised' said President Abdullah Gül as he inaugurated the Marmaray tunnel between the European and Asian sides of Istanbul on October 29, as part of the Republic Day celebrations marking the 90th anniversary of Atatürk's proclamation of the Turkish Republic.
Guests at the opening of the 'project of the century' included Romanian Prime Minister Victor Ponta and Somalian President Hasan Sheikh Mahmud. Also present was Prime Minister Shinzo Abe from major funding partner Japan, who ambitiously suggested that the line could one day form part of a rail route from Tokyo to Istanbul and London.
Initial operations will be limited to metro-style services on the core tunnel section of the route, including a 4 min journey through the immersed tube under the Bosporus between Sirkeci and Üsküdar. Work is still underway to upgrade the suburban railways at either end of the tunnel, with trains expected to run over the full 76·3 km between Halkali and Gebze from mid-2015.
Project of the century
Plans for a tunnel across the Bosporus were first developed during the reign of Sultan Abdülmecid in 1860, and the scheme was revived on a number of occasions. A comprehensive study in 1987 established that the project was feasible and selected the alignment, including the 1·4 km immersed tube tunnel said to be the deepest in the world at 60 m, and 12·2 km of mainly bored tunnel with four underground stations.
Turkey and Japan International Cooperation Agency signed a financing agreement in 1999. Preparatory works began in 2001 and construction of the tunnel in August 2004, with the immersed tube completed in February 2009. Works at Sirkeci station were delayed by significant archaeological discoveries. The government's General Directorate of Infrastructure Investments is project promoter, with state railway TCDD responsible for operation.