When vehicle tunnels are constructed through rock, the roof and walls are sprayed with concrete to create an even surface layer and prevent stones from loosening and falling onto the road.

There has been vociferous opposition to the tunnel by those who think increasing road capacity will in turn ... it will be attractive to HGVs that will drive through Greenwich and Newham ...

Image Credit: Chalmers University of Technology When vehicle tunnels are constructed through rock, the roof and walls are sprayed with concrete to create an even surface layer and prevent stones from ...