15 minutes (Halkalı – Gebze) Marmaray (pronounced [ˈmaɾmaɾaj] ⓘ) is a 76.6-kilometre-long (47.6 mi) commuter rail line located in Istanbul, Turkey.

[3] 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.

A third line was added to enable the electric multiple unit (EMU) cars and other railway carriages to move separately.

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.

[18] In February 2010, Railway Gazette International reported that the tunnel's administrators were hiring consultants to analyse options for carrying freight traffic.

[19] 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.

The Japan International Cooperation Agency (JICA) and the European Investment Bank (EBI) provided much of the financing for the project.

The original €580 million contract called for 440 vehicles to be produced locally by Eurotem, Hyundai Rotem's joint venture with Turkish rolling stock manufacturer TÜVASAŞ.

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.

[12] Archaeologists also 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 as planned.

This demonstrated that the China to Turkey transportation time could be reduced from a month to 12 days as part of the Iron Silk Road concept.

The waterlogged, silty soil on which the tunnel is constructed has been known to liquefy during an earthquake so engineers injected industrial grout to 24 metres (79 ft) below the seabed to keep it stable.