|Marmaray, the world's deepest immersed tube tunnel at 60.46 metres (198.4 ft)|
|Start||Fatih, Istanbul, Turkey|
|End||Üsküdar, Istanbul, Turkey|
|No. of stations||41|
|Work begun||May 9, 2004|
|Opened||October 29, 2013|
|Length||13.6 km (8.5 mi)|
|Line length||76.3 km (47.4 mi)|
|No. of tracks||track on surface with additional passing loops|
1,435 mm (4 ft 8.5 in)Standard gauge
|Operating speed||45 km/h (28 mph)|
Marmaray (pronounced [ˈmaɾmaˌɾaj] ( )) is a rail transport project in the Turkish city of Istanbul. It comprises an undersea rail tunnel under the Bosphorus strait, and the modernization of existing suburban railway lines along the Sea of Marmara from Halkalı on the European side to Gebze on the Asian side. The procurement of new rolling stock for suburban passenger traffic is also part of the project. Construction started in 2004, with an initial target opening date of April 2009. After multiple delays caused by the discovery of historical and archaeological finds, the first phase of the project opened on October 29, 2013. It is the first standard gauge rail connection between Europe and Asia.
The name Marmaray 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 Turkish press has compared it to the Silk Road.
The construction contract for the project was awarded to a Japanese-Turkish consortium led by Taisei Corporation in July 2004. The consortium included Kumagai Gumi, Gama Endustri Tesisleri Imalat ve Montaj, Nurol Construction, and Trade of Turkey.
The project includes a 13.6-kilometre (8.5 mi) Bosphorus crossing, the upgrade of 63 kilometres (39 mi) of suburban train lines to create a 76.3-kilometre (47.4 mi) high-capacity line between Gebze and Halkalı, and the provision of 440 electric multiple unit cars.
The Bosphorus (Istanbul Strait) is crossed by a 1.4-kilometre-long (0.87 mi) earthquake-proofed immersed tube, assembled from 11 sections; eight are 135 metres (443 ft), two are 98.5 metres (323 ft), and one element is 110 metres (360 ft) long. The elements weigh up to 18,000 tons. The sections have been placed down to 60 metres (197 ft) below sea level: 55 metres (180 ft) of water and 4.6 metres (15 ft) of earth. This underwater tube is accessed by bored tunnels from Kazlıçeşme on the European side and Ayrılıkçeşme on the Asian side of Istanbul. It represents the world's deepest undersea immersed tube tunnel. Fire-resistant concrete developed in Norway was crucial for the safety of the project.
New underground stations have been built at Yenikapı, Sirkeci, and Üsküdar. Thirty-seven other above-ground stations along the line will be rebuilt or refurbished. The station at Yenikapi connects with Istanbul Metro and Istanbul LRT. The above-ground suburban lines have been upgraded to three tracks, two for commuter and one for long-distance/high-speed passenger trains (bi-directional). The tunnel section allows for two, bi-directional tracks to be used by commuter and long-distance trains. During off-peak hours, freight trains will also cross the tunnel. The capacity for the suburban lines is planned for 75,000 passengers per hour in each direction. Signaling is also modernized to allow trains to be as close as two minutes apart. The predicted travel time from Gebze to Halkalı is 104 minutes.
Construction of the Marmaray project started in May 2004. The Marmaray tunnel was completed on September 23, 2008, with a formal ceremony to mark completion of the tunnel on October 13. Completion of the entire project had been repeatedly delayed, and as of December 2009, was expected to occur in October 2013. On October 29, 2013 the first stage of Marmaray project, covering the underground connection between Europe and Asia, was inaugurated. Since then, passengers can travel between Yenikapı and İbrahimağa.  In the early days after opening, trains had to stop several times which caused hard discussions in Turkey. These stoppages were explained to be caused by curious passengers using emergency brakes. 
The second stage is the renewal of current railway on ground, between Gebze and İbrahimağa on the Asian side and between Yenikapı and Halkalı on the European side. It is scheduled to be completed in 2015. A third line will be added which will provide the metro cars and other rail cars the ability to move separately. Only after completion of this stage, it'll be possible for trains to cross from Europe to Asia or vice versa. 
After completion, the usage of rail transportation in Istanbul is predicted to rise from 3.6% to 27.7%.
Although not officially announced by TCDD, the Prime Minister and officers stated several times that Marmaray will help to bring back the use of the term "Silk Road" with a new name of "Iron Silk Road" by allowing freight trains to move between Europe and China. Freight trains free of dangerous goods will be able to move through the tunnel during the time metro cars are not working.
5 or 10 cars per train
|Operator||Turkish State Railways|
|Floor height||1,300 mm (51 in)|
|Electric system(s)||Overhead line|
|Current collection method||Pantograph|
1,435 mm (4 ft 8.5 in)Standard gauge
Hyundai Rotem announced on November 11, 2008, that it had signed a €580 million contract to supply the rolling stock for the Marmaray cross-Bosphorus tunnel project in Istanbul. The Korean firm had competition from shortlisted bidders Alstom, CAF, and a consortium of Bombardier, Siemens, and Nurol for the 440-vehicle contract which was placed by the Ministry of Transport's General Directorate of Railways, Harbours, and Airports.
The 22-metre-long (72 ft) stainless steel cars will be formed into ten-car and five-car EMUs. Some production will be carried out locally by Eurotem, Hyundai Rotem's joint venture with Turkish rolling stock manufacturer TÜVASAŞ. The cars will arrive in three batches: the first 160 cars by 2011 and the last by June 2014.
The project was delayed four years, largely due to the discovery of a Byzantine-era and other 8,000-year-old archaeological finds on the proposed site of the European tunnel terminal in 2005. The excavations produced evidence of the city's largest harbour, the 4th-century Harbour of Eleutherios (later known as the Harbour of Theodosius). There, archaeologists uncovered traces of the city wall of Constantine the Great, and the remains of several ships, including what appears to be the only ancient or early medieval galley ever discovered, preventing the project from proceeding at full speed. In addition, the excavation has uncovered the oldest evidence of settlement in Istanbul, with artifacts, including amphorae, pottery fragments, shells, pieces of bone, horse skulls, and nine human skulls found in a bag, dating back to 6,000 BCE. Glass artefacts and fragments dating from the Hellenistic, Roman, Byzantine and Ottoman periods have been found during excavations at Sirkeci.
The suburban rail upgrade section of the project, known originally as CR1, was first awarded to the AMD Rail Consortium of Japan's Marubeni, Turkey's Dogus Insaat and France's Alstom. However, it faltered and the work was re-tendered as contract CR3 in early 2011. The replacement contract worth €932·8 million was awarded to a joint venture of OHL and Invensys Rail.
Tunnel construction is only about 18 kilometres (11 mi) from the active North Anatolian Fault, worrying engineers and seismologists. "Since AD 342, it has seen large earthquakes that each claimed more than 10,000 lives." Scientific calculations to estimate the probability that at some time in the next 30 years the area will suffer an earthquake of strength 7.0 or more produced an outcome of 77 percent. The waterlogged, silty soil on which the tunnel is constructed has been known to liquefy during an earthquake; to solve this problem, engineers injected industrial grout down to 24 metres (79 ft) below the seabed to keep it stable. The walls of the tunnel are made of waterproof concrete coated with a steel shell, each independently watertight. The tunnel is made to flex and bend, similar to the way tall buildings are constructed to react if an earthquake hits. Floodgates at the joints of the tunnel are able to close and isolate water in the event of the walls' failure.
Steen Lykke, project manager for Avrasyaconsult, the international consortium that is overseeing the construction, sums it up, saying, "I can't think of any challenge this project lacks".
The Japan International Cooperation Agency (JICA) and the European Investment Bank have provided major financing for the project. As of April 2006, JICA had lent 111 billion yen and EIB 1.05 billion euro. The total cost of the project is expected to be approximately 2.5 billion US dollars. As of late 2009, costs were expected to increase by approximately 500 million US dollars due to the archaeological delays.
On August 4, 2013, Prime Minister Recep Tayyip Erdoğan was the driver for the first test ride on Marmaray. The ride started from Ayrılıkçeşmesi station (older name İbrahimağa station) at the Asian side and ended at a distance of about 10 km (6.2 mi) on the European side crossing Bosphorus underwater, and then back.
It was announced that the first phase of the Marmaray project consisting of four stations would go into service on October 29, 2013, the 90th anniversary of the foundation of the Turkish Republic. The travel time on the first section, connecting both sides of the Bosphorus, being 19 minutes. The completion of the entire project is expected in 2015.
The tunnel was officially opened on October 29, 2013 on the Turkish Republic's 90th anniversary Republic Day. The maiden journey took place following the grand opening ceremony attended by Turkish President Abdullah Gül and Prime Minister Recep Tayyip Erdoğan, as well as Japanese Prime Minister Shinzō Abe, Romanian Prime Minister Victor Ponta, Somali President Hassan Sheikh Mohamud, and a number of foreign civil servants.
Following the opening ceremony, commuter trains now go from Ayrılıkçeşme station (Asian side) to Kazlıçeşme station (European side), stopping at 3 underground stations along the way.
Suicide threat scandal
After the opening ceremony it was discovered that Turkish authorities threatened their Japanese counterparts working on Marmaray that they would commit suicide if the project did not finish before the October 2013 deadline.
- Ministry Infrastructure Investment Director General Metin Tahan, saying that he and other Turks working on the project would commit suicide if the project were not finished by the scheduled deadline.
Marmaray in numbers
Some figures of the project are as follows:
- Overall length: 76.3 km (47.4 mi)
- Tunnel section: 13.6 km (8.5 mi)
- Immersed tube: 1,387 m (4,551 ft)
- Deepest point: 60.46 m (198.4 ft)
- Minimum curve radius: 300 m (980 ft)
- Maximum gradient: %1.8
- Surface stations: 37
- Underground stations: 3
- Interchanges: 4
- Inter-city stations: 8
- Minimum platform length: 225 m (738 ft)
- Average station spacing: 1.9 km (1.2 mi)
- Maximum speed: 100 km/h (62 mph)
- Commercial speed: 45 km/h (28 mph)
- Headway: 2–10 minutes
- Passengers per hour and direction: 75,000
- Number of passenger cars: 440
Note: Station of Mustafakemal is actually one of Kanarya, which is quarter of Küçükçekmece district.
- Rails under the Bosporus, Railway Gazette International 2009-02-23
- "Marmaray tunnel opens to link Europe with Asia". Railway Gazette International. October 29, 2013.
- "TCDD launches Eskisehir – Konya high speed service". Railway Gazette International. March 28, 2013. Retrieved October 28, 2013.
- "Istanbul, apre il tunnel sotto il Bosforo: la "Via della Seta 2.0" (Silk Road 2.0)" (in Italian). la Repubblica. October 29, 2013. Retrieved October 30, 2013.
- "MARMARAY: THE MODERN DAY SILK ROAD". Sabah English. October 29, 2013. Retrieved October 30, 2013.
- "Marmaray Projekt: Ein Tunnel unter dem Bosporus für Istanbul" (in German). M-hesse.com. May 2011. Retrieved October 28, 2013.
- Smith, Julian. "The Big Dig" Wired Sept. 2007: pages 154–61.
- "Norwegian technology in the world's deepest immersed tunnel" (in Norwegian) Teknisk Ukeblad, October 12, 2013. Accessed: October 13, 2013. Technical report: Claus K. Larsen. "Testing of fireproofing for concrete" Norwegian Public Roads Administration, 2007.
- Facts and figures, web page at the Marmaray web site. Accessed on-line September 24, 2007.
- Travel time and alignment, web page at the Marmaray web site. Accessed on line, September 24, 2007.
- Istanbul Metro and LRT, web page at the Marmaray web site. Accessed on-line September 24, 2007.
- Istanbul, web page at urbanrail.net. Accessed on line September 24, 2007.
- Final tubes sunk on Bosphorus Tunnel, International Railway Journal, November 2008.
- Marmaray completion delayed to 2013, cost increases by $500 mln, Today's Zaman 2009-12-19
- Uysal, Onur. "Marmaray Opened", Rail Turkey, 29 October 2013
- Uysal, Onur. "Marmaray Started With Discussions", Rail Turkey, 6 November 2013
- Uysal, Onur. "Completely False Facts About Marmaray", Rail Turkey, 20 May 2013
- Contracts February 2010, Railway Gazette International 2010-02-09
- Uysal, Onur. "Is Marmaray Key for Europe-Asia Rail Connection?", Rail Turkey, 12 November 2013
- Marmaray train contract signed, Railway Gazette International 2008-11-14
- Tunnel links continents, uncovers ancient history CNN
- Rose, Mark; Aydingün, Sengül. "Under Istanbul". Archaeology.org. Archaeological Institute of America. Retrieved October 27, 2008. ; Nautical archaeology takes a leap forward, The Times, December 31, 2007
- Üzlifat Canav-Özgümüş. "Recent glass finds in Istanbul" Doğuş University, September 2012. Accessed: October 13, 2013.
- "Marmaray railway upgrading contract awarded". Railway Gazette International. Nov 3, 2011.
- Marmaray completion delayed to 2013, cost increases by $500 mln, Today's Zaman 2009-12-19
- "Marmaray'ın güzergahı değişebilir". Hürriyet (in Turkish). June 30, 2009. Retrieved August 6, 2013.
- "Başbakan Erdoğan Marmaray'da test sürüşü yaptı". Hürriyet (in Turkish). August 4, 2013. Retrieved August 6, 2013.
- "Turkey ready to take first ride on landmark undersea train line". Today's Zaman. October 28, 2013.
|Wikimedia Commons has media related to Marmaray.|
- Marmaray project official website
- Overview of the Marmary history, justification, and construction process with pictures
- Marmaray Project:
- L. C. F. Ingerslev, 2005, "Considerations and strategies behind the design and construction requirements of the Istanbul Strait immersed tunnel," Tunnelling and Underground Space Technology 20: 604–08.
- Steen Lykke and Hüseyin Belkaya, 2005, "The project and its management," Tunnelling and Underground Space Technology 20: 600–03.
- Steen Lykke and Frits van de Kerk, 2005, "Marine operations, the Bosphorus Crossing," Tunnelling and Underground Space Technology 20: 609–11.
- Hideki Sakaeda, 2005, "Tunnels and stations in BC contract," Tunnelling and Underground Space Technology 20: 612–16.
- Ahmet Gokce, Fumio Koyama, Masahiko Tsuchiya, Turgut Gencoglu, 2009, "The challenges involved in concrete works of Marmaray immersed tunnel with service life beyond 100 years," Tunnelling and Underground Space Technology 24: 592–601.
- Istanbul Technical University Marmaray Laboratory web site.
- Tunnelbuilder technical description.
- (Turkish) Marmaray BC1 project and surveying works
- BBC article on the project.