The Osmangazi Bridge is a suspension bridge spanning the Gulf of İzmit at its narrowest point, 2,620 m (8,600 ft). The bridge links the Turkish city of Gebze to the Yalova Province and carries the O-5 motorway across the gulf. The bridge was opened on 1 July 2016 and surpassed the Fatih Sultan Mehmet Bridge to become the longest bridge in Turkey and the sixth-longest suspension bridge in the world by the length of its central span.
The length of the bridge is expected to be surpassed by the Çanakkale 1915 Bridge, which is currently under construction across the Dardanelles strait.
Construction and operation of the bridge was awarded to a joint venture (NOMAYG JV) 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 ₺11 billion for the entire highway from Gebze to Bursa.
After the completion of the bridge, the distance between Istanbul and İzmir shortened by about 140 km (87 mi), bypassing the long-stretched Gulf of İzmit. The 420 km (260 mi) highway and bridge reduced the travel time between the two major cities from six-and-half hours to three-and-half hours. The bridge and the connecting highway provide three lanes of traffic in each direction. The construction was completed on 30 June 2016.