The Longest Suspension Bridge in the World Connects Asia to Europe

This Week in Engineering explores the latest in engineering from academia, government and industry.

Episode Summary:

The recently opened 1915 Çanakkale Bridge in Turkey is an engineering marvel. The world’s largest suspension bridge, the project was thought to be technically impossible as late as the mid-1990s but has emerged as a key link between Europe and Asia.  

The bridge required very high towers and large, submerged caissons built on-site, as well as advanced project management and planning. Some 4,000 workers built the bridge which—despite COVID-19—was completed ahead of schedule. A consortium of two Korean and two Turkish engineering firms handled the construction, and will operate the bridge for 16 years before turning control over to the Turkish government. The estimated cost of the project is $2.7 billion, and it is expected to carry as many as 45,000 vehicles per day. 

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Transcript of this week’s show:

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For millennia, large-scale civil engineering projects have been symbols of progress and a source of national pride, from the Pyramids to modern structures like the Burj Dubai.  

 Major bridge projects can serve a dual purpose: they can carry that symbolic meaning, and also address more practical concerns of traffic flow. There are several chokepoints that restrict motor traffic flow between Europe and Asia, most notably the Bosporus, the Sea of Marmara and the Dardanelles Straight. Linking Asia through Turkey to Europe has always been important, and with expanding global trade the existing bridges and tunnels in operation now at the Bosporus are inadequate to handle growing traffic.  

A logical place for a new bridge was Çanakkale, where the Dardanelles Straits narrow—although at some 4 km wide, narrow is a relative term. The Turkish government realized this as far back as the mid-1990s, but studies determined that a suspension bridge of that size was unfeasible with the then-current technology.  

Some two decades later, a new study by Pyunghwa Engineering Consultants determined that the project was feasible with available technology and did preliminary design work. Denmark’s COWI won the contract for detail design, with Parsons and Tekfen handling project management. On January 26, 2017, construction contracts were signed with a consortium consisting of Korea’s Daelim and SK Engineering and Construction, and Turkish civil engineering firms Limak and Yapi Merkezi. The overall project includes the marquee 1915 Çanakkale Bridge and 89 km of connecting highway.  

The bridge structure is record-breaking. The main span is 6,637 feet long, making the structure the longest suspension bridge in the world with an overall length of 11,690 feet. Suspension bridges by design require higher towers to support increased span, and the bridge’s towers rise 1,043 feet, measured to the intersection point of the main cable, making the project the sixth tallest bridge in the world.  

Towers were built using submerged 66,000-ton caissons, 40 and 48 m below the surface. While the tower height is dictated by physics, it is also symbolic. At 308 m, it commemorates the March 18, 1915 victory of the Turkish Navy against the British. The reinforced concrete deck supports six lanes of traffic with two maintenance walkways and is 148 feet wide, 11 feet thick and lies 239 feet above the Strait. The deck’s split design addresses winds, and the entire structure is designed to accommodate seismic activity in the region.  

The bridge was officially opened by Turkish President Recip Erdogan on the 18th of March.  

The 1915 Çanakkale Bridge is the sixth link between Asia and Europe, after three bridges over the Bosporus near Istanbul and two tunnels beneath. However, it is the first fixed crossing over the Dardanelles. The project’s overall cost was $2.7 billion, and the toll for using the bridge is approximately $14. The four major construction partners will operate the bridge for 16 years, after which control will pass to the Turkish government. And despite COVID-19, the large and complex project—employing 4,000 workers—was completed ahead of schedule. 

Written by

James Anderton

Jim Anderton is the Director of Content for Mr. Anderton was formerly editor of Canadian Metalworking Magazine and has contributed to a wide range of print and on-line publications, including Design Engineering, Canadian Plastics, Service Station and Garage Management, Autovision, and the National Post. He also brings prior industry experience in quality and part design for a Tier One automotive supplier.