Towards a Sustainable Society

Introducing our main achievements : Civil Engineering

Project with Stories

A Partner in Turkey's 150 Year Dream:Bosphorus Strait Crossing Railway Tunnel

Recipient of the Prime Minister's Award

Recipient of the Prime Minister's Award

Client : General Directorate of Railways Ports and Airports
Construction (DLH), Turkish Ministry of Transport

Design : Taisei, Gama, Nurol JV

Partial opening : October 2013

Location : Istanbul, Republic of Turkey

The Bosphorus Straits Crossing Railway Tunnel has been constructed as a national project of the Republic of Turkey. An undersea tunnel is said to be a “150 year dream”, envisaged since the time of the Ottoman Empire. The Bosphorus Strait which connects Asia and Europe divides Turkey's main city Istanbul into two, and has been an obstacle to traffic from ancient times. With economic development in recent times traffic congestion and atmospheric pollution have become more serious, so in August 2004 work on construction of a railway tunnel that is capable of large volume transport commenced supported by a yen loan from the Japanese Government. This is a giant project implemented by a joint venture of Taisei Corporation together with 2 Turkish construction companies, with a total length of about 13.6 km. The most advanced tunneling techniques were used for constructing the tunnel: the approximately 1.4 km undersea tunnel was constructed by the immersed tunnel method, and the on-land tunnel was constructed by a combination of the shield tunnel method and the NATM method, etc. This was a difficult project requiring construction under severe and highly difficult natural environmental conditions and detailed response to conservation of archeological and historical structures, but the railway was opened on 29th October 2013 on the 90th anniversary of the proclamation of the Republic of Turkey. The opening ceremony was attended by both Prime Minister Erdoğan and Prime Minister Abe.

Technology Window

The undersea tunnel was constructed by the immersed tunnel method in which concrete elements are immersed to the bottom of the sea and joined. Immersion to a depth of 60 m from the surface of the sea, the world's deepest, for an immersed tunnel was achieved using IT, etc., to deal with the complex and rapid tidal currents in the Bosphorus Strait. In addition, the undersea tunnel (immersed tunnel method) and the land tunnel (shield tunnel method) were directly connected under the sea. This is the first time in the world that this was accomplished, and it required great accuracy and safety. On the other hand the portion of the tunnel on land was carried out by the shield method, excavating underground with a shield machine, and by the NATM method at the densely built up area around Sirkeci Station. The ideal construction methods were adopted taking into consideration the locality which contains many historical structures as well as the effect on buildings.

  • Direct connection of different types of tunnel (schematic diagram of connection between shield tunnel and immersed tunnel element)

    Direct connection of different types of tunnel (schematic diagram of connection between shield tunnel and immersed tunnel element)

  • World's first working vessel for constructing RC immersed tunnel element on the sea and immersing them

    World's first working vessel for constructing RC immersed tunnel element on the sea and immersing them

  • The NATM method was used for construction below the built up area around Sirkeci Station, due to restricted operating land

    The NATM method was used for construction below the built up area around Sirkeci Station, due to restricted operating land


Hidemi Ohmi

Hidemi Ohmi
Senior Managing Executive Officer In charge of Marmaray Project BC1

“By combining all our efforts, we accomplished everything up until opening”

This project was an engineering, procurement, and construction contract (EPC contract*). We were responsible for virtually everything up until opening of the railway, from determining the alignment of the underground railway, the configuration of services and systems, preparation of maintenance and operation manuals, and training. In addition, this was a site that required the greatest care and bold ideas, such as marine operations in the strait under complex currents, excavation of tunnels under historic buildings that have degraded with time, etc. Of these, what made it possible to safely and reliably complete such a large scale construction was the culture of resolutely taking up new challenges, and comprehensive technical capability such as design, construction, IT, etc. I feel that this is a project that has demonstrated to the world the capabilities of Taisei.

Masahiko Tsuchiya

Masahiko Tsuchiya
Design Project Manager

“We Realized a Bold Design and Construct Proposal”

In EPC contracts, normally the contractor plans everything based on the requirements of the customer. The specification to satisfy the required function is determined and proposed by the contractor. From an early stage we strove to gain the client's confidence. In the beginning we sensed an atmosphere of doubt regarding the design departments of general contractors, which are rare in Europe, but I believe we demonstrated our strengths by effectively undertaking both the design and construction. In this case there were many technical challenges, so from the design stage there was close communication with the Construction Division. Searching for specific methods of realization and sharing ideas from the stage of determining the specification was a contributor to the success of the project. The proof of this is the fact that the confidence of the client suddenly increased after seeing the product.

Kazunori Ito

Kazunori Ito
Construction Manager

“Appropriate Prior Studies make successful results”

A feature of the tidal currents in the Bosphorus Strait is that they are greatly affected by the weather, so forecast of the tidal current changes are difficult. It was essential to develop a system to forecast the tidal currents for safe operation of immersed tunnel installation. This system uses IT to deliver analysis forecast data based on monitoring site data. The data delivered via the web shows the tidal currents for a continuous 36 hours. Before commencement of construction work, we researched the available technical papers and conducted many hydraulic physical models at the Technology Center, but the truth is we had concerns until we started work on site. However, as measurement data accumulated the forecast accuracy also increased, so we became more confident. Also, we keenly felt the need for logic and suitable explanations through managing the Turkish staff and negotiating with the client. I believe that developing the skills of each member of staff will lead to further overseas expansion.

Tolga Pulak

Tolga Pulak
Construction Engineer, IMT Div.

“I have Grown Greatly as an Engineer and a Manager”

After being involved in all processes of the immersed tunnel from production of the elements to the immersion operation, I was transferred to the Design Department where I was responsible for work supervision and communication and coordination with other relevant organizations. Having experienced a wide range of work, I have been able to obtain overall project management knowledge. I have worked to be able to contribute to the maximum extent, by responding to the instructions of my bosses and avidly absorbing knowledge. This was my first experience of construction of an immersed tunnel, so initially I was unsure whether I could perform my work well, but seeing the success with my own eyes gave me great confidence. For the future I want to further study technologies, share my knowledge and experience with my colleagues as a manager, and accumulate many more marvelous successes like this one.

* One of the forms of contract for construction such as buildings, factories, power stations, etc. It indicates a construction project contract that includes design (engineering), procurement and construction.

Introducing our main achievements

Coal Unloading Jetty and Connecting Bridge

This jetty extends 2.2 km offshore, and was constructed to provide docking and unloading capability for coal ships of up to 150,000 dwt as well as transport facilities for Taiwan Power Company's coal-fired power plant outside Kaohsiung city. This large-scale jetty construction was undertaken in Taiwan's coastal area of typhoon-prone seas, requiring full implementation of Taisei's most advanced marine engineering know-how.

Client : Taiwan Power Company

Design : Union-Tech Engineering Consultants Co.

Completion : April 2008

Location : No. 125, Minzhi Rd., Qieding Dist., Kaohsiung City 852, Taiwan

Coal Unloading Jetty and Connecting Bridge

Bangkok Industrial Ring Road, Cable-stayed Bridges

Taisei constructed this pair of steel and concrete long-span hybrid cable-stayed bridges across the Chao Phraya River. These bridges form part of the Industrial Ring Road that connects the Center of Bangkok to the outlying districts. The bridges contribute to economic development in the area by significantly shortening transport time between the southern industrial district and the city of Bangkok, where goods previously had to be transported by ferry.

Client : Ministry of Transport, Kingdom of Thailand

Design : Mott MacDonald JV

Completion : August 2006

Location : Prapadaeng, Samutprakarn, Bangkok City, Kingdom of Thailand

Bangkok Industrial Ring Road, Cable-stayed Bridges

Southern Transport Development Project-Package2

The Southern Colombo Highway, the first genuine motorway in Sri Lanka, was completed in November 2011. The construction started in 2006, and extends 100km from Colombo to Galle, a famous world-heritage sightseeing city situated on the southwestern tip of Sri Lanka. The completion of this highway has led to considerable tourist development and the subsequent flow of foreign currency, as well as an increase in local employment. This in turn contributes to the elimination of poverty and closing the wealth‐gap between regions.

Client : Road Development Authority (Sri Lanka)

Design : Oriental Consultants Co., Ltd.

Completion : November 2011

Location : Dodangoda~Kurundugahetekma Sri Lanka

Southern Transport Development Project-Package2

Bali Beach Conservation Project, Package IV: Shore Protection Works for Kuta Beach

Artificial beach nourishment work was carried out on the Indonesian island of Bali to protect the sand beach in Kuta district from erosion and simultaneously safeguard the landscape of this major tourism resource. Shore protection was performed by evenly laying sand taken from the seabed and removing unnecessary sea banks and tetrapods. This environmental project also transplanted corals within the reef (35,000 m2) as part of an environmental conservation measure. At present, the lively beach is attracting many tourists and local residents.

Client : Ministry of Public Works of Indonesia

Design : Nippon Koei Co., Ltd. JV

Completion : December 2008

Location : Kuta District, Bali, Republic of Indonesia

Bali Beach Conservation Project, Package IV: Shore Protection Works for Kuta Beach

Sagami Traverse Hayamajima Tunnel

This is a road tunnel between Hayamajima and Ogura in Midori-ku ,Sagamihara City on the Sagami Transverse Road as part of the Ken-Ō Expressway, located at a radius of 40 to 60 km from the center of Tokyo. The tunnels in both directions, each 2.1 km long and 73 m2 internal cross-sectional area, were excavated by the NATM method. Ground improvement work was also carried out at the sag (the depression between the downward slope and upward slope).

Client : Kanto Regional Development Bureau, Ministry of Land, Infrastructure,Transport and Tourism

Design : Kanto Regional Development Bureau, Ministry of Land, Infrastructure,Transport and Tourism

Completion : February 2014

Location : Sagamihara City, Kanagawa Prefecture

Sagami Traverse Hayamajima Tunnel

Shirako River Underground Flood Control Reservoir (No. 5)

This is a flood control reservoir for temporarily storing water during a floor, in response to short localized downpours of rain of recent years. A shield tunnel internal diameter 10.0 m and about 3.2 km long was constructed along Mejiro Dori Avenue, and when there is a rise in water levels the tunnel can receive water from both the Shirako River and the Shakujii River. This is the first case of a flood control reservoir being connected to several rivers in Tokyo. The storage capacity is 212,000 m3, corresponding to a rainfall of 50 mm in 1 hour.

Client : Tokyo Metropolitan Government Bureau of Construction (No. 4 Construction Office)

Design : Tokyo Metropolitan Government Bureau of Construction

Completion : January 2014

Location : Nerima-ku, Tokyo

Shirako River Underground Flood Control Reservoir (No. 5)

New Tomei Expressway Aokigawa Bridge

This is a long span bridge as part of the New Tomei Expressway. The project was implemented by the design and construct method, the first time for the client, Central Nippon Expressway Company Ltd. The structural form was determined from the given conditions: a corrugated steel web box girder superstructure and hollow bridge piers using high strength reinforcement. The bridge was constructed in a short period of time using advanced technologies such as installation of a temporary platform for environmental considerations, construction of large blocks using a very large traveling erection gantry, etc.

Client : Central Nippon Expressway Company Ltd., Nagoya Branch

Design : Taisei-Oriental Shiraishi Joint Venture (design and construct)

Consultants : Chuo-Fukken Consultants Co., Ltd., Nippon Koei Co., Ltd., Oriental Consultants Co., Ltd., Yokohama Consulting Center

Completion : May 2013

Location : Okazaki City, Aichi Prefecture

New Tomei Expressway Aokigawa Bridge

Southern Contract 907 Construction and Completion of Landmark Station Including Associated Tunnels for Downtown Line

The longest metro in Singapore, Downtown Line, with 40 kilometers in length and a total of 33 stations, is currently under construction over a separated period of three terms. The 907 work package, which we built in the first term (completed in 2013), was constructed under an all-in contract including the downtown metro, as well as the west and east sides of the open-cut tunnel, and completed on September 30, 2013. On December 21, the day it commenced its operation, an opening ceremony was held with Prime Minister, Lee Hsien Loong, as a guest of honor.

Client : Land Transport Authority of Singapore

Design : AECOM Singapore Pte Ltd.

Completion : September 2013

Location : Marina Bay area, Singapore

Southern Contract 907 Construction and Completion of Landmark Station Including Associated Tunnels for Downtown Line
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