Marmaray () is a long intercontinental commuter rail line 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. 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 prime minister 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 Halkali. ==Project== The project involved building a tunnel under the Bosphorus and upgrading of 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. The consortium included Gama Endustri Tesisleri Imalat ve Montaj and Nurol Construction. 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 weigh