What are the challenges of tunneling?

Modern challenges in tunnel construction

1) Dusty conditions. With trucks taking rock and spoil away from the tunnel at all hours of the day, waterproofing membrane can become a difficult task because of the airborne particles such as silica dust and diesel particulates. ...
2) Delivery of membrane. ...
3) Membrane damage.

Do tunnels go underwater?

Various methods are used to construct underwater tunnels, including an immersed tube and a submerged floating tunnel. The immersed tube method involves steel tube segments that are positioned in a trench in the sea floor and joined together. The trench is then covered and the water pumped from the tunnel.