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Major milestone achieved on Izmit Bay Bridge

Photo: COWI

​Immersion of 40.000 tons foundations with 25 m steel shafts for the Izmit Bay Bridge.

​The COWI designed Izmit Bay Suspension Bridge reached a significant milestone with a successful installation of two tower foundations. The Turkish Prime Minister visited the site and praised the construction and the great importance of the Izmit Bay Bridge.  

During two major operations carried out on March 15 and March 26 the two 40.000 tons tower foundations for the COWI designed Izmit Bay Suspension Bridge were successfully immersed and installed into their final position. The bridge is part of a new, extended highway system connecting Istanbul and Izmir.  

The total length is 3 km and with a 1550 m main span the bridge will have the 4th longest bridge span in the world. Yet one of the crucial factors in the high quality design is the ability to build the bridge on a 37 month record short construction period.

“We are very pleased to see this major milestone achieved within schedule which emphasises our position as one of the world’s leading consultancy firms on suspension bridges,” says Kent Fuglsang, Project Manager, International Bridges, COWI.


International teamwork 

During 18 months COWI had a world class team of around 100 people from COWI offices in Copenhagen, San Francisco and London each contributing with their field of expertise and working closely together on the detailed design. The COWI design enabled the Japanese main contractor IHI to construct the two foundations within a record short period of only 13 months.

“One of the most important parameters in our detailed design has been to facilitate easy and fast construction of the structures in order for the main contractor to meet a tight schedule,” says Flemming Pedersen, Deputy Project Manager. 

Each of the two foundations consists of a 54 m x 67 m and 15 m tall concrete caisson with an earth-quake resistant construction. Next to each other the two caissons take up the space equivalent of an international soccer field and reach the height of a five-story building. Furthermore each caisson supports two 25 m composite shafts with two concrete plinths and a tie-beam above sea level. 

“The construction of the caissons commenced in February 2013 in a purpose made dry-dock. After completion of the initial part in the dry-dock the caissons were towed to a wet-dock in September 2013 where the underwater concrete works were completed and the prefabricated steel shaft installed before the caissons were towed out and immersed into their permanent location at approximately 40 m water depth,” explains Flemming Pedersen, and continues: 

“Next important step in the construction of the tower foundations is the completion of the plinths and the tie-beams before the assembly of the steel pylons can start in June this year.”

Published 10.04.14

LAST UPDATED: 16.09.2016