Lead Pipe

The leading pipe designed to fit the rear of a jacking shield and over which the trailing end of the shield is fitted.

Line

(1) The specified direction of the proposed bore in a horizontal plane. (2) (Path) The shortest distance between two points as laid out by a survey crew for the installation of pipelines and their bores and tunnels.

Liner Plate

A proprietary product, used to line tunnels instead of casing, and comes in formed steel segments. When these segments are bolted together they form a structural tube to protect the tunnel from collapsing. The segments are made so that they may be bolted together from inside the tunnel.

Lining

A rehabilitation process where a length of material is introduced to extend the life of the existing sewer. The lining may or may not utilize some structural strength from the existing sewer,  and it may or may not function as a structural enhancement within the existing sewer, or an internal non-structural coating or lining material applied to a pipe.