The Osman Gazi Bridge (Turkish: Osman Gazi Köprüsü) is a suspension bridge, located at the Gulf of İzmit along the eastern end of the Sea of Marmara, in close vicinity of Izmit and approximately 50 km (31 mi) southeast of Istanbul, Turkey. It is the fourth-longest suspension bridge in the world by the length of its central span.
Construction and operation of the bridge was awarded to a joint venture formed by five Turkish companies (Nurol, Özaltın, Makyol, Yüksel and Gocay) and one Italian construction company Astaldi following the international Build–operate–transfer tender that took place in April 2009. In 2010, a contract was signed for the project that was estimated to cost Turkish lira symbol 8x10px.png11 billion for the entire highway from Gebze to Bursa. After the completion of the bridge, the distance between Istanbul and İzmir will shorten about 140 km (87 mi) bypassing the long-stretched Gulf of İzmit. The projected highway of 420 km (260 mi) length with the bridge will reduce the travel time between the two major cities from six-and-half hours to three-and-half hours. The construction is completed in 30 June 2016.
On March 30, 2013, Prime minister Recep Tayyip Erdoğan laid the ground stone for the bridge.
EPC Bridge Contractor
The US$1 billion privately financed bridge was awarded to the Japanese firm IHI Infrastructure System Co. on 16 July 2011 as EPC basis with FIDIC Silverbook contract. IHI, which was one of the contractors of second Bosphorus bridge, also completed the seismic reinforcement projects for Halic and Mecidiyekoy viaducts.
IHI subcontracted the design works to Danish engineering design firm COWI A/S. The bridge will connect the northeastern and southeastern coast of the Izmit Bay, significantly reducing regional travel time. Crossing the bay, the bridge and the connecting highway will provide three lanes of traffic in each direction. Notice to proceed was given by Nomayg to IHI on 1 January 2013 and total project duration is 37 months.
The most important dimensions are:
main span length: 1,550 m (5,090 ft)
side spans length: 566 m (1,857 ft)
clearance: 64 m (210 ft)
tower height: 252.0 m (826.8 ft)
tower size (at the base): 8 m × 7 m (26 ft × 23 ft)
deck size: 35.93 m × 4.75 m (117.9 ft × 15.6 ft)
The bridge is fourth longest suspension bridge in the world
Accident at construction site
On March 21, 2015, a catwalk broke away from its bolted joint cable on the south tower during the construction at the bridge and fell into the water. Added in February 2015, the catwalk was needed to allow workers access to the other side of the bay. No one was harmed by the accident as work was interrupted at this section due to windy weather. Marine traffic to and from İzmit Bay was suspended following the accident for security reasons and resumed after recovering the cable in the morning of March 23.
Kishi Ryoichi, the 51-year-old Japanese engineer of the IHI-Itochu Consortium, who was in charge of the construction at site, committed suicide by cutting his wrist and throat with a blade knife. He was found dead at the entrance of a cemetery near his lodging in Altınova. He left a note saying that "...this failure ends my private and professional life. This project was mine and my country's pride. No one else is responsible for this failure."