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Izmit Bay Bridge Opens for Traffic

Photo: IHI

​The world's fourth longest suspension bridge is now officially open to commuters! With a free span of 1550 metres between its pylons and a total length of almost three kilometres, the impressive Izmit Bay Bridge, named the Osman Gazi Bridge, in Turkey will contribute to reducing travel time from Istanbul to İzmir with up to six hours.

​Thursday 30 June, the Izmit Bay Bridge opened to traffic. President Erdoğan and the Prime Minister attended the grand inauguration ceremony. In collaboration with IHI, COWI has carried out the design of the Izmit Bay Suspension Bridge. The impressive construction is the world’s fourth longest suspension bridge and will cut a 70-minute drive around Izmit Gulf to just six minutes. It is in other words very welcomed by thousands of commuters.

"Opening of the Izmit Bridge after totally 42 months of construction is a fantastic achievement and COWI's support throughout the project period has without doubt been a major factor in this achievement. All team members can be very proud of having been part of this world class project and the final result", states Kent Fuglsang, Project Director, Major Bridges International.

The total length is 3 km and with 1550 metres 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 record short construction period.

Finishing the Izmit Bay Bridge is a major accomplishment for COWI. It is an impressive project to add to the list of record setting bridge, which among others include the Great Belt Bridge in Denmark and Stonecutters Bridge in Hong Kong – just to mention a few of COWI's major bridge designs.


Izmit Bay Bridge is built in one of most seismically active areas in the world, which places additional demands on the bridge’s design. In contrast to the Great Belt Bridge in Denmark, the design team decided to use steel instead of concrete for the Izmit Bridge’s 250-metre-high pylons.

"In 1999, a major 7.5 magnitude earthquake occurred close to the bridge site, and we had to provide innovative solutions in the design to protect the bridge and the users against another major earthquake that almost without any doubt will hit the area during the life time of the bridge", explains Kent Fuglsang.

Based on knowledge from COWI's earthquake specialists, the bridge is made earthquake resistant by building its pylons on a concrete foundation that rests on a large gravel bed the pylons can slide on in the event of a major earthquake. The bridge is thereby partly isolated from the enormous energy, which a major earthquake releases.

Published: 05.07.2016

LAST UPDATED: 24.05.2017