A three-level subsea tunnel under Istanbul’s Bosphorus Strait, which will connect the city’s two sides with one railway and two highways, has been put out to tender for feasibility efforts.
Four companies have presented technical and financial offers in the tender for project and engineering services for the “Grand Istanbul Tunnel,” which is estimated to be worth $3.5 billion.
The tender for the project was first released on Aug. 10, 2016, with İdom, Tecnimont and Yüksel Project firms’ financial offers, but it was later declared null due to a financial mistake in one of the companies’ offer.
This year the offers were made by Tecnimont Civil Const., İtalfer-Sintagma, Arcadsi-Prota and Yüksel companies.
The price for the feasibility bid was determined to be 30 million Turkish Liras, with some 7.5 million liras of the funds allocated to feasibility, engineering and deep drilling works that will take place over this year. The authorities will determine the ground data for the project.
The three-level tunnel will pass under the Bosphorus, featuring tubes for cars and trains. Trains will pass through a tube in the middle, while tubes below and above will be for vehicular transit.
One part of the planned 6.5 kilometer-long tunnel will connect a high speed subway system from the İncirli neighborhood on the European side to the Söğütlüçeşme neighborhood on the Asian side. The second part will connect a two-lane land route between Hasdal on the European side and Çamlık on the Asian side.
The tunnel will be integrated into nine subway lines, the TEM Motorway, the E-5 Motorway and the Northern Marmara Motorway, according to officials.
Around 6.5 million passengers are expected to use the tunnel on a daily basis once it is completed in the next five years.
Passengers will be able to reach Söğütlüçeşme from İncirli in 40 minutes. The travel time between Hasdal and Çamlık will be reduced to 14 minutes.
The tunnel will be the largest in the world in terms of size and capacity.
The project was launched in 2015 by then-Prime Minister Ahmet Davutoğlu.
“The three-level megaproject will be the signal flare of the Turkish Republic, the fourth global state in Istanbul after three empires,” he said in a publicity meeting for the project on Feb. 27, 2015 at the Istanbul Congress Center, adding that the tunnel is “the first of its kind in the world.”
He said the Bosphorus Bridge, the Fatih Sultan Mehmet Bridge, and the Yavuz Sultan Selim Bridge, which was under construction at the time, but is now functioning, will all be connected to each other once the tunnel is completed.
It was also announced that the subsea tunnel will be built with a build-operate-transfer model in the form of a public-private-partnership scheme, so “the state will not have to pay a single penny.”
Some 2,800 workers are planned to be employed for the construction, and 800 more workers will be employed once it goes into operation.