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News

January 24, 2014

A New Bridge of Friendship between Turkey and Japan
A subway opens traversing the Bosphorus

On Oct. 29, 2013, the 90th anniversary of the founding of the Republic of Turkey, a ceremony was held to mark the opening of a subway traversing the Bosphorus. Attending the ceremony were Turkish President Abdullah Gül, Prime Minister Recep Tayyip Erdoğan, Minister of Transport, Maritime Affairs and Communication Binali Yıldırım, and on the Japanese side, Prime Minister Shinzo Abe. At the ceremony, which was held on Turkey's Republic Day celebrating the founding of the republic, the historical importance of the project connecting Asia and Europe was on display.

JICA supported the project by providing Japanese ODA loans totaling 196 billion yen since 1999. The strong ties between Turkey and Japan were the driving force that overcame every kind of physical and economic difficulty, said Akio Saito, chief representative of the JICA Turkey Office.

What follows is a look at the ties among the various stakeholders in the subway.

photoSubway map (Kazlicesme station to Ayrilikcesme station)

Helping realize a 150 year dream of the Turkish people

The Bosphorus strait bisects Istanbul, Turkey's largest city, and it has been an obstacle to transportation since antiquity.

"We want to unify this city that is divided by the strait."

In 1860, the time of the Ottoman Turks, plans had already been drawn for a tunnel to transverse the strait. In the background of the realization of this dream of the Turkish people over the course of 150 years was a strong partnership of trust between Japan and Turkey that also spanned many years.

The strait has been spanned by two suspension bridges, but chronic traffic congestion and accompanying air pollution from exhaust gas were becoming more serious. As a means of transport to alleviate congestion and environmental problems at the same time, the Turkish government planned a subway to transverse the strait. Since 1999, Japan has supported construction through Japanese ODA loans, and Taisei Corporation, along with a joint venture (TGN) between Turkey's Gama Endustri Tesisleri Imalat ve Montaj and Nurol Construction, built the subway, including the undersea tunnel between Kazlicesme station and Ayrilikcesme station.

While doing the construction, they were expected to work in a way befitting an historic city, constructing a subway and stations while being careful not to damage buried cultural assets, and using the advanced technology necessary to construct the world's deepest immersed tube tunnel (*1) on the sea floor at 60 meters under water, under the severe conditions of the fast tidal current that flows in the channel and dense maritime traffic.

With the opening of the subway, the time required for a trip across the strait, which used to be around 30 minutes by ferry, was reduced to about four minutes. The subway is expected to carry 1.5 million people per day by 2015.

photoA cross-sectional schematic of the tunnel

Training young engineers amid a series of difficulties

photoUsing a work barge (catamaran ship) to lower an enclosure to the sea floor. The enclosure is in the foreground.

The work TGN carried out was a project of extending the subway 13.6 kilometers total. This encompassed building a 1.4 kilometer immersed tube tunnel under the sea floor, two 9.5 kilometer shield tunnels (*2) connecting to each side of the tube tunnel, three underground stations and one aboveground station. Taisei Corporation, which constructed the Seikan Tunnel (1989) and the Kobe-Naruto route of the Honshu-Shikoku Highway (1997), was in charge of construction of the undersea tunnel, thought to be the most technically difficult of all those jobs.

"Construction of the immersed tube tunnel was a battle with nature."

These are the words of Taisei Corporation's Fumio Koyama, general manager at the Procurement Division, who was responsible for the immersed tube tunnel construction work from 2004 to 2009. First his team devoted nearly a year to gathering data on the flow and speed of the strait, and then it built a work barge.

The work at sea after that was, "like working on a raft (the barge) on a fast-flowing river (the strait). And off to the side everything from yachts to ferries and large tankers frequently came and went. If we slipped our moorings, it would have been a big accident."

Every day they had to advance their work while exercising great caution.

photoFumio Koyama, guiding the job of lowering the last enclosure in September 2008.

Hiring was also difficult.

"There were no local companies with immersed tube tunnel construction experience, so for the main underwater construction we directly hired everyone from engineers to laborers at our local office, without using any subcontractors," Koyama explained. Taisei carried out the construction by hiring young people eager to acquire new technology, and having Japanese supervisors provide technical guidance. While building the undersea tunnel, Taisei usually had about 30 engineers on the payroll. Many of those engineers used their newly acquired skills to move on to new jobs, but there is one who was hired in 2004 and is still working on site, as a manager.

"It was a series of mental strains, and to be honest, it was the kind of experience that shortens your life. Even so, forming a team with foreigners who have a different culture from mine and finishing this difficult construction work was a big accomplishment. The pride of an engineer having tackled this big project that connects Japan and Turkey as well as Asia and Europe gives everyone a strong feeling that 'there's no way I could give up,' and I have the feeling we finished a project that can be called a miracle," Koyama said with deep emotion.

The completed undersea tunnel is the world's deepest underwater tunnel constructed by sinking prefabricated box culverts, and the technique of using the shield method to connect the land section with the tunnel was a world first. In consideration of the fact that Turkey is an earthquake-prone country, the tunnel was given a design that could withstand a 7.5 magnitude earthquake.

Contributing financially and with risk countermeasures

photoIn August, Chief Representative Akio Saito of JICA Turkey office attends a trial run of the subway.(Photo by Ibrahim Unver)

It was JICA that contributed financially and with risk countermeasures. Since the beginning of construction work in August 2004, unexpected buried cultural assets have been discovered, causing enormous delays. Along with these delays, project costs have grown to be much more than what was estimated when the construction contract was formed.

JICA held seminars with UNESCO, aiming to maintain transparency in buried cultural asset surveys, and dispatched experts to secure the safety of the construction work. It also encouraged smooth coordination between Turkish government agencies so construction could be carried out without a hitch. To speed up procedures for paying construction costs, it tenaciously negotiated with the Turkish government.

Chief Representative Saito, who from 2001 has intermittently been involved in the project, said, "If the Turkish parliament had not approved the increased construction contract amount to accompany delays from the historical ruins survey, construction might have been interrupted."

photoThe remains of a wharf from the Roman era found near Yenikapi station

What allowed the difficult situation to overcome was the great efforts of Turkish government agencies, including the leadership of Prime Minister Erdoğan, who from when he was the mayor of Istanbul had been pushing forward this project. It was also because of the cooperation of consulting companies and TGN and the support of the Japanese Embassy, among others.

The friendship between Japan and Turkey began with the 1890 Ertuğrul Frigate disaster (*3) and deepened at the time of the 1985 Iran-Iraq War (*4). And now, the opening of a subway traversing the Bosphorus strait with Japan's technical and financial cooperation can be expected to become a new symbol of friendship between Turkey and Japan.

The opening of all lines, including pre-existing lines now being improved, is expected in 2015. Used for passenger trains during the day and freight trains at night, the tunnel is expected to become an artery for the physical distribution of goods among Europe, the Middle East and Asia. JICA will continue cooperating with its Turkish counterparts and providing support to keep the project running smoothly.


*1 A construction method of creating a box-shaped structure called an enclosure, carrying it with a barge and lowering it to the sea floor.

*2 A construction method of excavating from inside a large, cylindrical excavating machine called a tunneling shield, while then burying segments called panels.

*3 In 1890, when the Ottoman Turk frigate Ertuğrul was shipwrecked off Wakayama prefecture, local residents mounted a rescue effort and the Japanese navy delivered the surviving crew members to their home country using a Japanese frigate.

*4 Japanese people living in Iran and having trouble leaving were placed on a special Turkish government plane and rescued, in what the Turkish government called repayment of Japan's kindness in the Ertuğrul Frigate disaster.

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