Marmaray () is a commuter rail line located in Istanbul, Turkey. The line runs from Halkalı, on the European side, to Gebze, on the Asian side, along the north shore of the Sea of Marmara. Mostly using the right-of-way of two existing commuter rail lines, the Marmaray line linked the two lines via a tunnel under the Bosporus strait, becoming the first standard gauge rail connection between Europe and Asia (all prior connections ran through Russia and used the incompatible Russian broad gauge). The two existing sections of the line were rebuilt and expanded from two tracks to three tracks, to allow for higher capacity with intercity and freight rail. The name Marmaray is a portmanteau of the words Marmara and Ray, which is Turkish for rail.
History
Construction started in 2004 and was originally intended to be completed by April 2009. After multiple delays caused – among other things – by the discovery of historical and archaeological sites along the route as new stations were built, the first phase of the project was finally opened by president Erdoğan on October 29, 2013. The second phase of the project was scheduled to open in 2015 but work once again stopped in 2014. It was restarted in February 2017 and the line finally opened in its entirety on March 12, 2019. The trains came with completely new rolling stock, with carriages that can be walked through from end to end.
The line can carry 75,000 passengers per hour in each direction (PPHPD). Travel time from Halkali to Gebze normally takes 104 minutes.
The Marmaray is integrated with other parts of the Istanbul public transport network, including the Metro and the Metrobus network, via a number of interchanges. It is also integrated with the YHT high-speed train network to Ankara, Eskişehir and Konya, as well as with the international trains to Sofia in Bulgaria which depart from Halkalı.
<!--is this the medieval trade route or the modern rail link?-->==Project==
The project involved building a tunnel under the Bosphorus and upgrading of existing suburban railway lines to create a high-capacity passenger line between Halkalı and Gebze, along with the provision of 440 electric multiple unit carriages.
First phase
The contract for the project was awarded to a Japanese-Turkish consortium led by Taisei Corporation in July 2004.
thumb|Plaque at the [[Üsküdar railway station commemorating Japanese-Turkish partnership]]
The Bosphorus (Istanbul Strait) is crossed by a earthquake-proofed immersed tube, assembled from 11 sections – eight are long, two are , and one element is . Each section weighs up to 18,000 tons. The tube was placed below sea level, beneath of water and of earth.
Construction started in May 2004 and the Marmaray tunnel was completed on September 23, 2008, with a formal ceremony to mark its completion on October 13.
thumb|upright=0.9|Path of the rail tunnel project (dotted line) within the Marmaray railway, across the Bosphorus strait
Second phase
The second phase of the project involved the renewal of the old suburban railway that ran between Halkalı and Kazlıçeşme on the European side of Istanbul and between Ayrılıkçeşmesi and Gebze on the Asian side. The work was meant to be completed at the same time as the first phase (the tunnel and underground sections), but was delayed until March, 2019.
A third line was added to enable the electric multiple unit (EMU) cars and other railway carriages to move separately. Signalling was also modernised to allow trains to travel as close as two minutes apart (although in reality far fewer trains than that actually run).
The suburban-rail upgrade part of the project, known originally as CR1, was first awarded to the AMD Rail Consortium, comprising Marubeni of Japan, Dogus Insaat of Turkey and Alstom of France. However, they were unable to complete the work and it was re-tendered as contract CR3 in early 2011. The replacement contract worth €932.8 million was awarded to a joint venture between OHL and Invensys Rail. The Prime Minister and other officials have suggested that the Marmaray will help to create a modern "Iron Silk Road" by allowing freight trains to travel between Europe and China. Freight trains that are not carrying dangerous goods will be able to use the tunnel when commuter services are not operating (between 1:00 a.m. and 5:00 a.m.). At other times only passenger trains will be in the tunnels.
Financing
The Japan International Cooperation Agency (JICA) and the European Investment Bank (EBI) provided much of the financing for the project. By April 2006, the JICA had lent 111 billion yen and the EIB 1.05 billion euro for the work. The original cost was estimated at $4.5 billion although it finally cost almost twice that.
Rolling stock
The Marmaray uses TCDD E32000 rolling stock manufactured by Hyundai Rotem in ten- and five-car EMU configurations. The original contract called for 440 vehicles to be produced locally by Eurotem, Hyundai Rotem's joint venture with Turkish rolling stock manufacturer TÜVASAŞ. Hyundai Rotem was chosen ahead of Alstom, CAF, and a consortium of Bombardier, Siemens, and Nurol.
There are two depot and maintenance yards on the line (one at each end) where the sets are stocked.
Archaeological discoveries during work on the Marmaray
The project was delayed by four years, largely due to the discovery of Byzantine-era and other 8,000-year-old archaeological finds on the proposed site of the European tunnel terminal at Yenikapı in 2005. Excavations then produced evidence of the city's largest harbour, the 4th-century Harbour of Eleutherios (originally known as the Harbour of Theodosius). In addition, archaeologists uncovered the oldest evidence of settlement in Istanbul, with artefacts, including amphorae, pottery fragments, shells, pieces of bone and horse skulls, and nine human skulls found in a bag, dating back to 6,000 BCE.
Opening
thumb|upright=1.2|Marmaray train passing under the Bosphorus as depicted in tile in Sirkeci Station
On August 4, 2013, Prime Minister Recep Tayyip Erdoğan, test-drove the Marmaray from Ayrılıkçeşmesi station (originally İbrahimağa station) on the Asian side under the Bosphorus and back again.
On October 29, 2013, the first stage of the Marmaray project, the underground tunnel between Europe and Asia, was inaugurated on the 90th anniversary of the Turkish Republic'. The maiden journey took place after a grand opening ceremony attended by President Abdullah Gül and Prime Minister Erdoğan, as well as by the Japanese Prime Minister Shinzō Abe, the Romanian Prime Minister Victor Ponta, the Somali President Hassan Sheikh Mohamud, and a number of foreign civil servants.
Earthquake protection
The tunnel construction is only about away from the active North Anatolian Fault and has worried some engineers and seismologists. "Since AD 342, it has seen large earthquakes that each claimed more than 10,000 lives."