The Project provides an upgrading of the commuter rail system in Istanbul,
connecting Halkalı on the European side with Gebze on the Asian side with an
uninterrupted, modern, high-capacity commuter rail system.
Railway tracks in both sides of Istanbul Strait will be connected to each other
through a railway tunnel connection under the Istanbul Strait. The line goes
underground at Yedikule, continues through the Yenikapı and Sirkeci new
underground stations, passes under the Istanbul Strait, connects to the Üsküdar
new underground station and emerges at Sögütlüçesme.
This Project is one of the major transportation infrastructure projects in the
world at present. The entire upgraded and new railway system will be
approximately 76 km long. The main structures and systems; include the immersed
tube tunnel, bored tunnels, cut-and-cover tunnels, at - grade structures, three
new underground stations, 37 surface stations (renovation and upgrading),
operations control centre, yards, workshops, maintenance facilities, upgrading
of existing tracks including a new third track on ground, completely new
electrical and mechanical systems and procurement of modern railway vehicles.
The idea of a railway tunnel under the Istanbul Strait was first raised in 1860.
However, where the tunnel under the Istanbul Strait crosses the deepest parts of
the Strait, the old-fashioned techniques would not allow the tunnel to be on or
under the seabed, and therefore the design indicated a "floating" type of tunnel
placed on pillars constructed on the seabed.
Such ideas developed further during the following decades, and a similar design
was developed in 1902 also showing a railway tunnel under the Istanbul Strait,
but this design indicates a tunnel placed on the seabed. Since then, several
different ideas have been tested and new technologies have allowed more freedom
in the design.
The technique that will be used in the Marmaray Project to cross the Istanbul
Strait - the immersed tube tunnel technique - has been developed since late in
the 19th century. The first immersed tube tunnel ever built was constructed in
North America for sewer purposes in 1894. The first tunnels for traffic purposes
constructed using this technique were also built in the United States. The first
one was the Michigan Central Railroad tunnel in 1906-1910. In Europe, Holland
was the first country to adopt the technique, and the Maas Tunnel in Rotterdam
was opened in 1942. . In Asia, Japan was the first country to adopt this
techniques and the two-tube road tunnel (Aji River Tunnel) in Osaka was opened
in 1944. However, such tunnels remained rare until a robust and well proven
industrial technique was developed in the 1950s, thereby allowing the
construction of large-scale projects in many countries.
The desire to construct a railway mass transit connection from west to east in
Istanbul and under the Istanbul Strait was becoming stronger and stronger in the
early 1980s, and consequently the first comprehensive feasibility study was
carried out and reported in 1987. This study concluded that such a connection
would be feasible and cost-effective, and the alignment we see in the project
today was selected as the best of a range of alignments.
The project as outlined in 1987 was discussed during the following years, and
around 1995 it was decided to make more detailed studies and update the
feasibility studies, including the passenger demand forecast from 1987. These
studies were concluded in 1998, and the conclusions underlined the earlier
conclusions that the project would offer many advantages to the people working
and living in Istanbul, and it would ease the rapidly growing problems regarding
traffic congestion in the city.
In 1999, a funding agreement between the Republic of Turkey and the Japanese
Bank for International Cooperation (JBIC) was signed. This loan agreement forms
the basis for the funding of the Istanbul Strait Crossing portion of the
Project, which represents some 35% of the costs for the entire railway project