Work Begins On ‘World’s Longest’ Underwater Tunnel

onstruction of the ‘world’s longest’ underwater tunnel has begun in Istanbul, Turkey. The 6.5 km Great Istanbul Tunnel has a scheduled opening date of 2028.

Construction of the ‘world’s longest’ underwater tunnel has begun in Istanbul, Turkey. It is officially named the Great Istanbul Tunnel, and it has a scheduled opening date of 2028, New Civil Engineer reports. The tunnel will be 18.8m in diameter and 110m below sea level. 

The Turkish Transport and Infrastructure Minister Adil Karaismailoğlu said that the tunnel would be one of the symbols of the “Century of Türkiye” vision as set out by the government last year. 

The tunnel will connect the European and Asian shores of Istanbul under the Bosphorus strait. It will be a total of 6.5 km (4 miles) in length and will carry a railway line and highway, with two tiers for road traffic and one for rail. It will have 13 stations and be integrated with Istanbul’s three airports and its metro stations.

Transport officials claim that the tunnel will carry 1.3 million passengers per day with a journey time of 40 minutes. The initial construction cost will be in the region of $3.5 USD. The investment is necessary to accommodate the predicted 3 million crossings per day of the Bosphorus within the next five years. 

There are currently two other tunnels providing routes under the Bosphorus: the Marmaray railway tunnel at 3.5km long, and the Eurasian road tunnel at 5.4km long. 

Ministers claim it will be the world’s longest underwater tunnel. However the 18 km Fehmarnbelt tunnel between Denmark and Germany is currently under construction, due to be completed in 2029. It will cross a stretch of the Baltic sea and have a dual road and rail system.

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