Underwater pedestrian tunnel crossing Istanbul's Bosphorus to go out to tender

An underwater pedestrian tunnel connecting Istanbul's European and Asian sides will go out to tender on March 27. 

The two-kilometers tunnel, with a diameter between 12 and 15 meters, will connect the Kabataş district on the European side to Üsküdar district on the Asian side and will include moving walkways as well as bicycle and electric vehicle lanes. 

The tender for drilling works was held in December 2016 and according to the tender agreement drilling works must be completed by March 12. 

Drilling work for the project, designed by the Istanbul Municipality's engineering and architecture company BİMTAŞ, was sold to an Ankara-based construction company for 7.5 million Turkish Liras. 

Istanbul Mayor Kadir Topbaş previously dubbed the tunnel a "crazy project" that heralded his "mastership period" as mayor. The entire project is expected to finish before Topbaş's third term ends in 2019. 

The tunnel will have two levels and will run 46 meters below the surface of the Bosphorus. On its top floor, pedestrians and cyclists will be able to commute between the continents, while on the bottom floor rubber tire-vehicles and electric cars will be able to drive.  

The tunnel will connect to a transportation transfer center, which is currently under construction in Kabataş and is designed in the shape of a seagull with open wings located on a 10,000-square-meter pedestrian concourse. Kabataş was shut down to maritime traffic in July.

The transfer center is expected to have multiple interchange platforms to sea and road traffic with the city's rail system.

Currently, commuters in Istanbul can use ferries, the Bosphorus Bridge (renamed the July 15 Martyrs' Bridge after the failed coup attempt of July 2016),...