What is an immersed tube tunnel? And are there any others in Britain/Europe?
A. An immersed tube tunnel is a tunnel made up of a number of ‘tube’ units which are constructed in a dry dock and floated out to their final location and then sunk into a dredged trench. The tube units are then fastened together and covered over for protection. The technique has many advantages over a bored tunnel (like the existing vehicle tunnel for example) and has been used for numerous tunnels in Europe. Contractor Bouygues TP was responsible for the recent construction of an immersed tube tunnel in Rostock, Germany. There are two examples in Britain at Medway, Kent, and Conwy in North Wales.
