A support structure for supporting vehicles one above the other during transport or storage, the structure comprising a base frame (12) having four corner posts (13) extending generally vertically when in use to support a separate upper frame (14) on which an upper vehicle can be supported in an elevated transport position, and one or more separate lower frames (15) arranged to be positioned within the base frame when in use on which a lower vehicle can be supported. The upper frame is guided up the corner posts when the upper vehicle is raised to its upper transport position and support means (23, 24, 25, 29, 30, 31) associated with the corner posts fasten the upper frame in its transport position relative to the corner posts. The base frame, upper and lower frames are transportable in a collapsed state when not in use by folding the corner posts down and collapsing the base frame, upper frame and lower frame so that they occupy less space with the upper, and lower and base frames in a nested configuration.
