Izmit Bay Suspension Bridge

Today we had the opportunity to visit the Gebze-Izmir Motorway and Izmit Bay Crossing. This project is the largest Build-Operate-Transfer project currently in operation in Turkey and the first motorway project of the country. Additionally it is also the second largest suspension bridge in Europe and the fourth largest suspension bridge in the world.

In order to reach the project site we had to use a ferry. This was a unique experience for all of us. Once we arrived at the project site, Nurettin Akdeniz, the Technical Manager of Bridge Construction gave us a presentation on the project as well as walked on site with us. In the end he joined us for lunch and shared his work experiences with us.

The project is a contract with the General Directorate of Highways and is approximately worth US$6.3 billion. Otoyol Yatirim ve Isletme A.S. SPV (Otoyol) was specifically created in September 2010 for this project.  Otoyol consists of a consortium of companies including Astaldi, Nurol Insaat, Ozaltin Insaat, Makyol Insaat and Gocay Insaat. The project spans 421 km between Izmir and Gebze. The bridge consists of two towers and has three spans. The concession period is 22 years and 4 months and this duration commences after all the parties involved in the project sign the construction contract. Construction officially began in July 2012. The design process takes 14 months and the liability for the design rests solely on the contractor. However multiple parties including URS Corporation is involved in checking for the accuracy of the bridge’s design. The project consists of 199 bridges and has in total 377 motorways.

Because of Turkey’s rapid growth, traffic in Turkey has grown immensely. This project aims to curb the deteriorating traffic conditions as well as aims to help increase the GDP of the country. It is estimated that because of this project travel distances will decrease by half. There is also a projected savings of 870 million Turkish Liras per year once this project is established. Once the motorway is constructed and in operation, new industrial developments in Balikesar and Manisa are also predicted. Marmara and Aegen Regions would also be connected to the motorway and help the industries in Turkey grow. The Izmit Bay crossing time would become 6 minutes through the suspension bridge as well. The travel time from Istanbul to Bursa would also decrease by an hour. Tourism in Antalya would also flourish once access is improved to the location because of easy access provided through this project. There is a strong motivation to finish the project early as it is projected that revenue from 40,000 vehicles per day would be acquired once the project starts. Delays caused in construction would result in loss of revenue acquired from these vehicles. This revenue is estimated to be around $2 million dollars a day.

The primary design objectives for the project included providing quality work in a short duration of time. Cost effectiveness, durability and serviceability were also important design objectives. Among many other tests and feasibility studies done for the project, wind tunnel tests were specifically done for the tower and the deck. As Turkey is prone to seismic activity, the bridge is designed to operate under these seismic conditions more specifically known as the Functional Evaluation Earthquake, Safety Evaluation Earthquake and No Collapse Earthquake. The bridge is estimated to have a 100 year bridge life.

This project uses a unique cable system. The strands used are known as PPWS – prefabricated parallel wire strands. 110 strands are used for each of the cables and each of these strands contains 127 wires each of which are 582 mm in diameter. Once on site before our site tour we had a brief safety meeting by IHS. Pictures of our site tour are given below.

After our site tour our hosts graciously volunteered to take us to lunch. We had the opportunity to indulge in authentic Turkish food and eat with the locals of the area. Everyone’s consensus was that this was by far the best meal we’ve had on the trip so far!