A wooden or more usually steel plate, but occasionally a concrete block used to fill a gap. In grouting, a packer is inserted and expanded to seal the hole for injecting grout only below the level of packer e.g. "tube � manchette" a special type of packer.

Any material used to fill the void between support members and the rock

The use of sheet metal to divert inflows of water from working areas so that concrete can be placed against a drier surface.

A parking / transportation system providing remote parking and mass transit service to a destination

A multi-level parking structure with access ramps for cars to reach each level

Tiny, physical objects in the air of any kind, e.g. dust. High levels can represent a form of air pollution

Companies, agencies or people who are affected by an issue or who seek resolution of an issue

Distribution of stream of materials over the receiving surface during shotcreting. A layer of shotcrete is built up by making several passes

A user, but not an operator, of a transit system or vehicle

In U.K. usage, the pedestrian movement area at the edge of a street. In U.S. usage, the carriageway area itself and/or its structural makeup

The line, or tunnel section, which constitutes limits of payment for excavation and concrete lining. Overbreak is any excavation beyond the pay line, and overrun is any excess concrete placed beyond the pay line. May also be referred to as the "B" line.

The line or tunnel section which constitues limits of payment for excavation and concrete lining. Overbreak is any excavation beyond the pay line, and overrun is any excess concrete placed beyond the pay line.

A person traveling on foot

The optimum speed with which a drill or excavator can advance through the ground in a short time before it is slowed or stopped by mechanical breakdown, ground instability, or the like.

Two perforated half round sections of sheet metal which are filled with grout, wired together, and installed in a hole. A steel bar with a rounded nose is forced inside the aleeve, causing the grout to squeeze through the perforations and bond to the sides of the hole.

Non-structural solid material placed inside or outside an immersed tunnel to increase its effective weight permanently

Issues pertaining to health or the functioning of living things

A small tunnel excavated over the entire length or over part of a larger tunnel, to explore ground conditions and/or to assist in final excavation. May also be referred to as "pilot drift".

Traveling support for the discharge line from a concrete placer.

Excavating a tunnel under air pressure.