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This article or section contains information about a planned or expected public transportation infrastructure. It may contain information of a speculative nature and the content may change dramatically as the construction and/or completion of the infrastructure approaches, and more information becomes available.

This article or section contains information about a planned or expected future tunnel. It may contain information of a speculative nature and the content may change as the construction or completion of the tunnel approaches, and more information becomes available.

Marmaray is the name of a project to link the European and Asian halves of Istanbul by an undersea rail tunnel across the Bosphorus strait. The name Marmaray (Marmara Rail) 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

The project includes a 13.6 km Bosphorus crossing and the upgrade of 63 km of suburban train lines to create a 76.3 km high capacity line between Gebze and Halkalı. The Bosphorus (Istanbul Strait) will be crossed by a 1.4 km earthquake-proof immersed tube, assembled from 11 sections, each as long as 440 feet and weighing up to 18,000 tons.^[1] The sections will be placed 56 meters below sea level, under 180 feet of water and 15 feet of earth.^[2] This tube will be accessed by bored tunnels from Kazlıçeşme on the European side and Ayrılıkçeşme on the Asian side of Istanbul. New underground stations will be built at Yenikapı, Sirkeci, and Üsküdar, and 37 other above-ground stations along the line will be rebuilt or refurbished.^[3][4] The station at Yenikapi will connect with Istanbul metro and light rail.^[5] The upgrade of the suburban lines requires the laying of a third track along most of the line to increase capacity to 75,000 passengers per hour in each direction. Signaling must also be modernized to allow headways of two minutes.^[6] Total travel time from Gebze to Halkali will be 104 minutes.<ref name="ff" />

Construction of the Marmaray project started in May 2004. Its completion, expected to occur in 2012,^[7] is projected to increase the fraction of trips in Istanbul made by rail transport from 3.6% to 27.7%. If this takes place, Istanbul's rail transport fraction will be third largest in the world, after Tokyo (60%) and New York City (31%).<ref name="tt" />

The project is currently two years behind schedule, largely due to the excavation of a Byzantine archaeological find on the proposed site of the European tunnel terminal. "In 2005, the dig ran into the remains of a fourth-century Constantinople port, Portus Theodosiacus."^[8] Researchers are recovering what appears to be the only Byzantine naval vessel ever discovered, preventing the project from proceeding at full speed. Each day the tunnel's progress is delayed is estimated to cost $1 million in revenue, yet Turkey cannot afford to destroy the site because it would hurt their chances of becoming part of the European Union. Some artifacts date back to the 6th millennium BC, the oldest settlements ever uncovered in Istanbul. Items found include amphorae, pottery fragments, shells, pieces of bone, horse skulls and nine human heads found in a bag.^[9]

Tunnel construction is only 12 miles from the active North Anatolian Fault, worrying engineers and seismologists. "Since AD 342, it has seen more than a dozen huge earthquakes that each claimed more than 10,000 lives." Scientists calculate the chances of the area being hit by a quake of 7.0 or greater may be as high as 77 percent. Waterlogged, silty soil like what the tunnel is being built upon has been known to liquefy during a quake and engineers are injecting industrial grout down to 80 feet below the seabed to keep it stable. The walls of the tunnel will be made of waterproof concrete and a steel shell, each independently watertight. The tunnel is made to flex and bend similar to the way a skyscraper is constructed if an earthquake occurs. Floodgates at the joints of the tunnel are able to slam down and isolate water in the event of the walls' failure.^[10]

Steen Lykke, project manager for Avrasyaconsult, the international consortium that's overseeing the construction, sums it up saying, "I can't think of any challenge this project lacks".^[11]

Financing

The Japan Bank for International Cooperation and the European Investment Bank have provided major financing for the project. To date (April 2006), JBIC has lent 111 billion yen and EIB 1.05 billion euros. Total cost of the project is expected to be approximately 2.5 billion euros (3 billion dollars).

See also

• Public transport in Istanbul
• Turkish Straits

References

External links

• Marmaray web site
• Istanbul Technical University Marmaray Laboratory web site
• Tunnelbuilder technical description
• Marmaray project: The project and its management, Steen Lykke and Hüseyin Belkaya, Tunnelling and Underground Space Technology, 20 (2005), pp. 600–603
• Considerations and strategies behind the design and construction requirements of the Istanbul Strait immersed tunnel, L. C. F. Ingerslev, Tunnelling and Underground Space Technology, 20 (2005), pp. 604–608
• Marmaray project: Marine operations, the Bosphorus Crossing, Steen Lykke and Frits van de Kerk, Tunnelling and Underground Space Technology, 20 (2005), pp. 609–611
• Marmaray project: Tunnels and stations in BC contract, Hideki Sakaeda, Tunnelling and Underground Space Technology, 20 (2005), pp. 612–616
• (Turkish) Marmaray BC1 project and surveying works
• BBC article on the project