Bosphorus bridges

Year:1973 - 2016

Duration:9 years

Cost:£11.6bn today

Country: Turkey

What did this project achieve?

Build road and rail bridges across the river Bosphorus

The Bosphorus is a narrow strait of water in northwestern Turkey. It’s part of the boundary between Europe and Asia and connects the Black Sea with the Sea of Marmara.

The Bosphorus is straddled by Istanbul - the capital of Turkey, with a population of 17m. Most of the strait’s shores are heavily populated.

Along with the Dardanelles, the Bosphorus forms the Turkish Straits. It’s a major access route to the Mediterranean Sea for many countries, including Russia and Ukraine.

There are three suspension bridges across the Bosphorus.

The first to be built was the 15th July Martyrs’ Bridge in 1973. At 1,560m long, it’s part of the O1 motorway.

The second – completed in 1988 – is the Fatih Sultan Mehmet Bridge. About 5km north of the first bridge, it’s 1,090m long and part of the Trans-European motorway.

The third – the Yavuz Sultan Selim Bridge – was completed in 2016. At 2,164m long, it’s near the northern end of the Bosphorus. The bridge is part of the Northern Marmara motorway.

Difference the projects have made

The three Bosphorus bridges all created essential links between key regions and made the movement of people and goods easier.

As part of the main routes between Europe and Asia, they’ve all helped to increase international trade. All three bridges are also credited with boosting local economies.

How the work was done

The 15th July Martyrs’ Bridge – originally called the Bosphorus Bridge – has a deck width of 33.4m and a main span of over 1km. When it opened, it was the fourth longest suspension bridge in the world. It’s now the 25th longest.

Engineers designed the structure as a gravity-anchored suspension bridge. This means its main cables are attached to the road deck, rather than the ground.

The project team used steel for the 165m towers. The road deck – which is 64m above sea level – was hung from zigzag steel cables.

The Fatih Sultan Mehmet Bridge has a main span of 1,080m and a deck width of 39m.

Engineers chose a more conventional design than the first bridge, using vertical hangars to hang the road deck.

The Yavuz Sultan Selim Bridge is a road and rail bridge. At 58.4m wide, it’s one of the widest suspension bridges in the world. The 322m tall structure is the second tallest bridge in the world of any type.

Engineers developed a 3D-computer model of the bridge to help with construction. One of the 3D model’s uses was to monitor the shrinkage and creep of concrete used for the structure.

Creep means how concrete ‘stretches’ or deforms under a continuous load. Creep doesn’t necessarily mean concrete fails or breaks. Engineers factor in creep when they design a concrete structure.

Shrinkage is the process of change as drying concrete changes and hardens. Shrinkage can increase stress on concrete and affect how much load a structure can take.

"​‌

Life can’t be all that bad…whatever happens, I can always take a long walk along the Bosphorus.

Orhan Pamuk

Turkish novelist and Nobel Prize winner

Fascinating facts

The Bosphorus bridge was renamed the 15th July Martyrs’ Bridge on 25 July 2016. This was following an attempted coup in Turkey on 15 July that year, when a faction of the Turkish army occupied and blocked the bridge. The soldiers surrendered to police and civilians the next day.

US tennis star Venus Williams played a show game with Turkish player İpek Şenoğlu on what was then the Bosphorus Bridge in May 2005. It was the first tennis match played on two continents.

The Yavuz Sultan Selim Bridge was named after Ottoman Sultan Selim I, who expanded the Ottoman Empire into the Middle East and North Africa in the early 16th century.

People who made it happen

  • Client: Turkish Highways Authority
  • 15th July Martyrs’ Bridge
    Structural engineers: Freeman Fox and Partners
    Designers: William Brown (ICE member), Gilberts Roberts, Michael Parsons
  • Fatih Sultan Mehmet Bridge
    Structural engineers: Freeman Fox and Partners
    Consulting engineer: William Brown (ICE member)
  • Yavuz Sultan Selim Bridge Designer: Michel Virlogeux
    Construction engineers: consortium of Turkish company İçtaş and Italian company Astaldi

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