Timber is a highly versatile construction material, strong and lightweight, with tremendous ease of handling and workability. It is both attractive in its appearance and in its environmental credentials. Correctly selected it has good durability, particularly in relation to de-icing salts. Bridges made from wood also tend to exhibit a natural empathy with the landscape. For the bridge designer, using timber offers a multitude of possible bridge forms ranging from simple beams to glue laminated arches, trusses and space frames.
Timber can also be used in conjunction with other materials such as natural stone, stainless steel and glass. Developments such as new, efficient connection techniques, modern wood based composites and stress laminated decks are further encouraging the use of timber for bridge building. Photographs of some modern bridges show the possibilities. This Digest covers the basic structural types, lists the standards for the different types of timber and composite that may be used, and discusses structural design including the evaluation of loads. Durability, detailing, connectors, parapets and handrails are covered briefly. 12 pages.