As the size of the tunnel and passing under the Bosphorus ground, one of the biggest Tunnel Boring Machine(TBM) in the world was sent from Germany in case of modules to Turkey.The main weldings of  excavation part have been carried out under the control of German Company Engineers.Each part has been controlled by radiographic testing method and successed in minimum revisions of weldings.

The connection of excavation part to the TBM Machine

The weldings have been made under the welding tent with convenient conditions.

The weldings of non-modular parts have been made under the difficult positions by using the safe platforms.