More studies for the Great Istanbul Tunnel under the Bosporus

Work has started on a geological condition field study for a proposed 6.5km three-deck road and rail tunnel under the Bosporus Strait in Istanbul, Turkey.

Average daily road traffic through the Great Istanbul Tunnel is expected to be 120,000 vehicles and the rail line will move around 75,000 people daily.

The tunnel, announced in 2015, will be nearly 19m in diameter and have two road levels and one rail level. It will run between Gayrettepe on the European side and Küçüksu on the Asian side.

The city transportation plan shows the tunnel as an integral part of the strategy to make travel more easy between Istanbul’s three airports - Istanbul Atatürk, Sabiha Gökçen and Istanbul New Airport.

Cost of the project will be around US$3.5 billion and delivered under a build–operate–transfer contract, according to Turkish media.

In December 2016, Istanbul’s 5.4km twin-deck Eurasia Tunnel opened for traffic, connecting the Asian and European side of the Bosporus strait. The tunnel, part of a 14.5km route costing $1.25 billion, carries around 100,000 vehicles a day.