3rd Bosporus Bridge

The pylons of the 3rd Bosporus bridge are rising to record height.
SCHWING is the main supplier for this the mega-project in Istanbul.

Istanbul, Turkey. The go-ahead for the commencement of the construction work to build a new bridge over the Bosporus was given on May 29, 2013 when the foundation stone was laid on the occasion of an official ceremony in the presence of Turkey’s President Abdullah Gül and of Prime Minister Tayyip Erdogan. With this project, Turkey continues to pursue the ambitious targets of implementing further measures to improve the country’s infrastructure.

The two existing road bridges in the centre of Istanbul crossing the heavily frequented strait used by merchant ships form a true bottleneck for the daily commuters in Istanbul, Europe’s largest metropolis with 14 million inhabitants. Estimates indicating a further increase in the number of 4.5 million cars registered to date and the future road link to the planned new major airport caused the authorities to launch a project for another bridge link in the northern part of the city. The new suspension bridge with an overall length of 1.3 km will span the Bosporus near the Black Sea between Garipce in Europe and Poyrazköy in Asia and thus relieve the through traffic with a new motorway section.

The newly founded ICA Consortium consisting of the Turkish Building Company IC İçtaş and the Italian Company Astaldi S.P.A. has been awarded the Contract as General Contractor for the construction of the bridge. The mega-project amounting to a total of 4.5 bn USD will be financed and implemented by way of the so-called “Build-Operate-Transfer” model. In this scheme, ICA will receive the concession to operate the bridge on completion of the project and can thus refinance the investment with the revenues generated by the toll rate. After a stipulated period of time of exactly 10 years, 2 months and 20 days, the structures will be transferred to the Turkish government.

The company responsible for the production and placing of concrete on site is the Turkish company Akcansa owned by HeidelbergCement AG. A special challenge of the building work is the necessity of pumping the concrete for the four bridge pylons up to the total future height of 322 m. For the purpose of elaborating the optimal concrete mix formula and to plan the site logistics, extensive consulting discussions with Akcansa and the participation of the local SCHWING representative were necessary before the order was placed. An economical global concept, fast machine availability and a list of references from comparable projects were the reason that SCHWING was appointed main supplier for this project. The main part of the order are three powerful stationary concrete pumps of the SP 4800 type as well as a supply of concrete pumping lines with an overall length of 3.800 m designed for a maximum concrete pressure of 200 bars. The scope of supply is completed by specially developed watertight SCHWING high-pressure shutoff gate valves and an extensive amount of cleaning and fastening hardware.

To respect the ambitious time schedule set by the Client, a project team was created at the SCHWING headquarters composed of staff from the technical, purchase, service, testing and distribution departments. After evaluating the results of a pumping test with a horizontally laid 500 m-long pumping line, the concrete mix formula could be fine-tuned and the concrete placing work for the bridge pylons be started right away. The equipment was commissioned by SCHWING service technicians who are now in permanent contact with the local project management. The reliable concrete pumps ensure that the four towers on both shores of the Bosporus will be rising up into the sky at an average rate of approximately 2 to 3 m per day. The working platforms equipped with climbing formwork are operated by 60 workers at the same time. The construction logistics are on schedule so that a total height of 210 m was reached in February 2014.

The elegant appearance of the structure realized as a combined cable-stayed and suspension bridge mirrors the design developed by the well-known French engineer Michel Virlogeux. The total height of 322 m is a new record for suspension bridge towers and also the 59 m-wide bridge deck accommodating 8 road-traffic lanes and two railway tracks is unique throughout the world.

The concrete placing operations will be terminated in October 2014 and the first traffic will be able to cross the Bosporus on the new bridge already next year. The connection of the bridge to the trunk road network is envisaged for the end of 2015.
In the meantime, the ambitious Turkish government is already focusing its attention on the tender for the next mega-project: the projected third airport will be designed for an annual volume of 150 million passengers and is earmarked for completion by 2017.