The under-construction Gebze-Izmir Motorway is the largest ever infrastructure project in Turkey’s history. The most notable feature of the project is the 3.3km Izmit Bay suspension bridge.

The $6.5bn road project will connect Gebze (located just east of the capital city İstanbul) and the city of İzmir in the Aegean region of Turkey with a 377km six-lane (three lanes in each direction) motorway. Access roads of 44km will also be built along with the motorway.

“The most notable feature of the project is the 3.3km Izmit Bay suspension bridge.”

The motorway project is being built through a public private partnership (PPP) and is the first road project in Turkey to be procured under the build operate transfer (BOT) model.

Concessionaire company Otoyol is implementing the project with a concession period of 22 years and four months, which includes a seven-year construction period. Otoyol is a consortium comprised of five Turkish companies, Nurol (18.50%), Özaltın (15.75%), Makyol (18.50%), Yüksel (15.75%) and Gocay (15.75%) and one Italian construction company Astaldi (15.75%).

The EPC contractor for the project is NOMAYG JV, which is a joint venture of the six companies comprising the BOT concessionaire.

The project broke ground in October 2010 and is set to be completed by 2018. It is expected to create approximately 10,000 construction jobs.

Gebze-Izmir Motorway Project details

The new motorway will shorten the road distance between Gebze and Izmir by more than 140km.

The 421km road project (377km motorway and 44 km connecting roads) will be completed in seven years and involves the construction of a 3km suspension bridge, 30 viaducts (total 18.21km in length), four tunnels (total 7.4km in length) and 209 bridges.

The project also includes 18 toll collection centres, five maintenance and operation centres, seven service areas and seven park areas.

The 53km Gebze-Orhangazi section of the motorway is being built as the first phase of the project. An EPC contract worth $2.3bn was awarded to NOMAYG JV in September 2011 for the construction of this stretch of the motorway. The section includes the Izmit Bay suspension bridge, which comprises the most complex part of the whole road project.

Benefits of the Gebze-Izmir Motorway

The existing route between Gebze and Izmir is 540km long and currently takes eight to ten hours to travel between the two places. The new motorway will reduce the average journey time between the two places to three to four hours, while relieving the traffic load on the existing route by more than 30%.

With the construction of the Izmit Bay suspension bridge, the gulf can be crossed in just six minutes compared to 70 minutes currently being taken with the use of peripheral state road.

Eurasia Tunnel Project, Istanbul, Turkey

Eurasia Tunnel Project is the construction of a 14.6km road link between the Kazlicesme and Goztepe regions of Turkey, including a 5.4km tunnel, that is being undertaken to address Istanbul’s increasing traffic problems.

The motorway will offer easy and safe connectivity between the Marmara and the Aegean regions of Turkey that together account for 60% of national GDP, 38% of freight transport and 41% of passenger transport in Turkey.

The Gebze-Izmir Motorway will also provide access to the İzmir Port, the ports in Marmara Region and the proposed Çandarlı Port.

Financing of the Gebze-Izmir motorway project

The $6.5bn cost is planned to be met though 50% equity and 50% debt. Bank Intesa, Citi Bank and Akbank are the financial advisors for the project.

Financing of $2.8bn towards the first phase of the project was completed in March 2013. Eight Turkish banks including Akbank, Finansbank and Ziraat Bankasi are providing 12.5% each for a credit facility of $1.4bn. International law firm Clifford Chance worked as the advisor to the lenders.

Construction of the Izmit Bay Bridge On the Gebze-Izmir motorway

The 3.3km Izmit Bay Bridge will be one of the largest suspension bridges in the world and the fourth longest suspension bridge by length of central span. The bridge will connect the northern and southern coasts of the İzmit Bay in western Turkey. It will be built at the eastern end of the Sea of Marmara, near İzmit.

The main span of the Izmit Bay suspension bridge will be 1,580m and the side span will be 566m. The vertical clearance will be 64m. The towers of the bridge will be 252m high with a base size of 8mx7m.

The bridge will use single cell steel orthotropic deck of 30.1m × 4.75m size supported by a pre-formed parallel wire strand cable system. The cable system in turn will be supported by anchor blocks.

The bridge is designed for earthquake resistance since it is located in a seismically active area.

The suspension bridge will have stiffened steel pylons built on concrete caisson foundation with steel piles. The foundation will rest on a gravel bed allowing the pylons to slide during earthquakes.

The bridge construction is estimated to require 85,000t of steel and about 125,000m3 of concrete.

Key players in the Gebze-Izmir motorway project

The international tender for the BOT motorway project was conducted by General Directorate of Highways, Turkey (TCK). The Turkish-Italian consortium was selected as the preferred contractor in April 2009.

The project implementation contract with Otoyol was signed in September 2010.

“The project broke ground in October 2010 and is set to be completed by 2018.”

BNV Mobility, a joint venture between Portuguese-based Brisa and the Netherlands-based NedMobiel, was appointed as the advisor for operation and maintenance (O&M) of the BOT motorway project.

The $1.1bn EPC contract for the suspension bridge was subcontracted to IIS-ITOCHU consortium in September 2011. The bridge is expected to be delivered by 2017.

Fugro carried out the geotechnical, geological and seismological survey works for the bridge project.

Cowi of Denmark was awarded a contract in September 2011 to carry out the detailed design of the suspension bridge. Halcrow is responsible for the independent design check on Cowi’s design. Denmark-based Dissing+Weitling is the architect of the bridge.