Ian McNeil Glossary #2

BRIDGE GLOSSARY 

Abutment a construction that takes the thrust of an arch or vault or supports the end
of a bridge

Arch a curved structure, usually in the vertical plane, that spans an opening or gap

Beam a long, straight piece of wood, metal or concrete used as a horizontal structural
member

Caisson a watertight compartment or chamber, open at the bottom and containing air
under pressure, used for carrying out work under water

Caisson disease Divers working at higher than normal atmospheric pressure breathe in
increased nitrogen, which is dissolved in the bloodstream. When they return to
normal pressure, the nitrogen forms bubbles which, if collected in the capillary
vessels, causes cramps (‘the bends’). If it collects in the joints, damage to nerve
endings can cause paralysis, temporary or permanent

Cantilever a beam or girder fixed at one end only; a part of a beam or structure which
projects beyond its support

Centring a temporary structure, usually of timber, which serves to support an arch
under construction

Coffer dam a watertight structure enclosing an area below water level, pumped dry so
that construction work can take place

Corbel a projection of timber or stone etc., jutting out from a wall to support a weight

Falsework a temporary framework used during building

Girder a substantial beam, usually made of iron or steel

Keystone the central stone forming the top of an arch or a dome or vault (also called a
quoin or headstone)

Lintel a horizontal beam as used over a door or a window

Pier a vertical member or pillar that bears a load

Pile a column of timber, iron, steel or concrete, driven into the ground or river-bed to
provide a foundation for a structure

Soffit the underside of a structure such as an arch, beam or stair

Spandrel the space between the shoulder of an arch and the surrounding rectangular
moulding or framework, or between the shoulders of adjoining arches and the
moulding above

Springer part of an arch where the curve begins; the lowest stone of this

Starling an arrangement, usually of piles, that surrounds a bridge pier to protect it
from erosion caused by scouring, debris etc.

Truss a structural framework of wood or metal, usually arranged in a formation of
triangles, forming a load-bearing structure

Voussoir a wedge-shaped stone or brick used in the construction of an arch or vault.