The Marmaray project in Istanbul is currently one of the largest transport projects in the world. It comprises 1.5km of immersed tunnel, 9.4km of twin bore tunnel, with the remainder in the New Austrian Tunnelling Method (NATM) and cut and cover sections.
The Marmaray tunnel not only connects with Europe and Asia, but is also part of a larger project that includes updating existing train lines and 37 existing stations, creating a new continuous line from Gebze to Halkali.
The project therefore combined the need to look at the following challenges: building a new rail tunnel under the Bosphorus strait and the effects this would have on the city - integrating the existing suburban railway lines, and protecting any historical and archaeological finds along the construction route.
23%increase in rail capacity and transportation
Modernising transport along the sea of Marmara
Carrying 70,000 passengers per hour across the Bosphorus in just four minutes, the tunnel will also reduce travel time from Gebze to Halkali by forty minutes.
Arup prepared the concept design of civil landworks including drainage, bridges, culverts, retaining walls, stations, trackworks, depot areas and roadworks.
The project combined the name of the Sea of Marmara, which lies just south of the project site, with ray - the Turkish word for rail.
Improving suburban travel
The 76km long tunnel also adds a third line parallel to the two existing ones, to help increase capacity and raise rail transportation levels from 4.6% to 27.7%.
Marmaray is the fourth underground system in Istanbul after Tünel Funicular, Metro and Kabataş–Taksim funicular and highly integrated with Metro lines.
We offered multidisciplinary services to carry out the project
Arup was commissioned to carry out a full peer review of all tunnel ventilation and smoke control system design reports, drawings, specifications, risk analysis management system, test procedures from preliminary design up to installation, commissioning and handover.
The scope of services also comprised the design of civil landworks including utilities, bridges, retaining walls, seawalls and roadworks at tender stage.
Arup also prepared the concept design of civil landworks including drainage, bridges, culverts, retaining walls, stations, trackworks, depot areas and roadworks in the Marmaray CR1 project during the tender stage, which is from Gebze to Halkalı.
Construction began in 2004, with the final phase of the project scheduled for 2017
The project is being financed by the Japan Bank for International Cooperation (JBIC) and the European Investment Bank (EIB). JBIC has lent $950m under a long-term low-cost loan while EIB provided a €650bn soft loan.
The construction contract has been assigned to a Japanese-Turkish consortium led by Taisei. The firms in the consortium include Kumagai Gumi of Japan, Gama and Nurol.