(5) Immersion Joint: The watertight joint that is dewatered when an element is installed at the seabed. It may remain flexible or can be made rigid, as is usual with steel tunnels. A temporary immersion gasket or soft nosed gasket is usually used, and an omega seal may also be installed later.

(4) Expansion Joint: A special moveable watertight joint between segments of a tunnel element.

(3) Earthquake Joint: An immersion joint of special design to accommodate large differential movements in any direction due to a seismic event. It is also applied to a semi-rigid or flexible joint strengthened to carry seismic loads and across which stressed or unstressed prestressing components may be installed.

(2) Construction Joint: A horizontal or vertical connection between monolithic parts of a structure, used to facilitate construction. A waterstop is commonly placed in such a joint.

(1) Closure or Final Joint: Where the last element has to be inserted rather than appended to the end of the previous element, a marginal gap will exist at the secondary end. This short length of tunnel will need to be cast-in-place and is known as the closure or final joint.

Used in comparative travel time and travel cost calculations. Comparison is also bound with preferences among mode of travel, waiting versus travel time and variability of travel time.

See Drill jumbo.

Any travelling frame used to support other items, such as drills, men, pipe for conveying concrete and conveyors.

One steel rib or unit of timber framing installed between two overstressed sets or between two pre-existing sets.

The least vertical distance between the deepest part of a floating body and the bed beneath.

Concrete, often ballast, placed in the lowest portion of an element.

Wood planking or other structural materials spanning the area between ribs.

Permission required to substantially change the land-level i.e. through excavation or land-filling within areas with development plans. Permission is obtained by the Building Committee

A term used for a discrete thickness of shotcrete (sprayed concrete), built up from a number of successive passes of the nozzle and allowed to set (see Pass).

(the making of) laws

The full period from the creation of a facility or object to its destruction, replacement and/or disposal. The planned life cycle may be very different from the actual life cycle

An analysis that compares project alternatives on the basis of a comparison over their respective full life-cycles taking account of differences in the timing of the investments. May focus only on issues that can be monetarized or may attempt to weigh monetarized issues against non-monetarized issues.

The cost of a project alternative resulting from a life-cycle analysis

Holes drilled in the bottom of the invert to fragment the rock in the invert. Because drills cannot be positioned to drill on the invert line, they have to be pitched slightly down in order to prevent tights.

Temporary lifting points from which an element is suspended during immersion, usually removed after an element is set on its foundation.