Abstract: A bridging unit for use in bridging apparatus for traversing a bridging zone, the bridging unit including a stowage housing which in use is disposed to one side of the zone, a spanning assembly operatively mounted to the stowage housing for movement between a stowed position and a deployed position in which it at least partially traverses the bridging zone in an elevated position, and deployment means operable to cause movement of the spanning assembly between the stowed and deployed positions.