Cross members

The lateral supports under the track of a boring machine.

Crossing

Pipeline installation in which the primary purpose is to provide one or more passages beneath a waterway, road, or other surface obstruction.

Crown

The highest point of the pipe or tunnel.

Crush Lining

See Pipe EatingSee In-Line Microtunneling..

CSO

Combined SewerAn underground pipe or conduit for transporting stormwater and/or wastewater. Overflow; a hydraulic relief point within combined sewer systems designed to discharge excess flows during wet weather to receiving waters.