Low-medium capacity rail system that does not always require a dedicated right-of-way

Iron or steel plates which can be fastened together to support the arch, sides, and in some cases the invert of a tunnel.

A casing of brick, concrete, shotcrete, iron, steel, or wood placed in a tunnel or shaft to provide final everlasting bearing structure of underground space and/or to finish the interior.

Liquid polluted products.

A device for measuring axial loads by means of strain pages attached to an elastic structural member, for which a calibration curve between applied load and gage readings has been established.

Backfill, usually granular, placed carefully around the lower part of a tunnel to hold it in position.

Procedure of drilling long holes to contain powder for breaking the rock in underground excavation. As an illustration, a tunnel may be excavated by first driving a pilot drift near the center of the tunnel. Then approximately 10 ft lengths of this drift are enlarged to full tunnel dimensions at intervals of 100 to 200 ft. THese excavated areas are used as working chambers to drill holes in the remaining rock to the next enlarged section. Holes are then loaded and exploded, with relief for the explosion provided by the pilot drift.

Non-reversible modifications suffered by the ground, resulting of the decrease of one or several stresses near an underground cavity

Acoustic intensity.

Compressed air used to facilitate tunnelling in soft or very wet ground by counterbalancing external hydrostatic pressures.Supplied at 5 to 40 psi.

Grout pumped through the concrete lining under low pressure to fill any voids between the concrete lining and the tunnel surface or between steel tunnel liners and backfill concrete.

Continuous tunnelling by means of boomheaders, tunnelling machines, TBMs, etc. Distinguished from drill-and-blast.

Drill jumbo that travels on the main rail line; has man platforms on the sides that can be folded back when not in use. After drillind out the round, the jumbo has to be moved back from the face to a passing track before the mucker can be moved in.

The act of caring for a facility or system to keep it in working order or to preserve its appearance or value

The cost of carrying out maintenance activities

The value an item would be worth if it were sold under normal market conditions

Good which is the object of exchange in a market

Provision for the movement of people in an urban area in unstructured groups, e.g. by bus, train, metro, etc

In geology, the homogeneous structure of a rock without any planar, directional arrangement of textural or structural features .

The removal of soil or rock by means of heavy cutting or digging equipment (not hand-held). Distinguished from hand mining and drill-and-blast excavation.