Cut And Cover
Cut-and-cover is one of the oldest methods of tunneling in urban areas where traffic or business interruptions due to large excavations shall be minimized. The method involves the installation of tunnel walls using conventional retention wall techniques (“cut”), typically followed by installing the tunnel roof as internal bracing slightly below the street level (“cover”).
The surface is then reinstated except for access openings. This allows early reinstatement of roadways, services, and other surface features. The final excavation and construction of the tunnel itself then take place under the permanent tunnel roof.