a novel design of a type of timber truss bridge that has been developed in kenya is described. the bridge comprises a number of identical timber frames that are assembled into trusses of the required span. two or more parallel trusses are supported on conventional abutments, and the timber deck rests on top of the trusses. loading tests carried out on individual frames, on groups of frames, and on complete bridges, have indicated that the design is suitable for bridges ranging in span from 12m to 24m required to carry limited numbers of vehicles up to 20t gross weight provided that the deck is accepted as contributing to the structural strength of the bridge. this assumption would not normally be made for bridges of this kind, but in practice measurements show that the deck does contribute significantly to the strength of the bridge. in lightly loaded situations, provided regular maintenance is undertaken, the bridge can be expected to have a life of 20 years. evidence of the durability of the bridge at higher traffic loadings is not available. the cost of the bridge in kenya is between one-half and one-fifth of comparable steel or concrete bridges.(a)

Want to know more about this project?