The structure will form part of the North Marmara Motorway, which will bypass the city and cross the Bosphorus to the north of Istanbul, thus relieving road traffic in the city and on the two existing suspension bridges further south.
With its innovative design and 1,408-m long central span, the structure has a 58-m wide deck carrying 2 x 4 traffic lanes and two railway lines in the middle.
The deck, which has a reinforced concrete back span and a metal central span, is held up by a hybrid suspension system comprising:
- 176 stay cables, requiring 8,400 tonnes of steel (1,960 MPa) and made up of parallel strands, the longest of which is 588 m
- Two 2,420-m long suspension cables holding 34 pairs of vertical hangers, supporting the central section of the deck.
The entire system is supported by two A-shaped concrete towers approximately 320 m in height.
"The Contracting Authority and the General Contractor have chosen the Freyssinet stay cable system for this exceptional structure. This confirms our customers' interest in our technology, and in particular its excellent performance and durability," says Jean-Daniel Lebon, Freyssinet Major Projects Director.
Construction began in the first quarter of 2013 and the structure will be completed in December 2015. The stay cables will be installed between September 2014 and July 2015.
When the bridge is complete, Freyssinet
will set a new record for the world's longest cable-stayed bridge, following
on from the Normandy Bridge in 1994 (856 m) and the Russky Island Bridge
in 2012 (1,104 m, the current record).
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