A bridge is a structure designed to cross a gap. They range in size from the tiny (a log across a stream) to the immense (kilometre long structures). Many bridges are engineering marvels, utilising massive amounts of ingenuity and knowledge. Building bridges out of LEGO is a popular activity amongst a large sub-group of fans particularly trainheads.
An arch bridge is a type of bridge in which vertical loads are partially transformed into horizontal forces, which are carried to supports (called abutments) on either side. The bridge deck can either be supported directly by the arch or suspended from the arch via cables. The deck can also be supported by trusses rising from an arch, to create a Truss-Arch bridge.
A notable example constructed entirely from LEGO elements is a model of the Sydney Harbour Bridge, roughly 12 feet (3.6m) long.
Suspension bridges are a class of bridges which use cables under tension to hang the bridge deck/load.
- See: suspension bridge.
Truss Bridges are a class of bridges which use frameworks, called trusses, to support the bridge deck from above, from below, or some combination of the two.
- See: truss bridge.