The role of timber bridges in the road system of Western Australia

The evolution of timber bridge design in Western Australia is outlined with reference to some notable early bridges and the way in which these structures were modified to cope with changing traffic needs. Details are given of current standard construction practice with special reference to the properties of timber. Design stresses used for various timbers are tabulated and methods used to rate bridges for vehicle load carrying capacity are briefly described. Maintenance of timber bridges is discussed including the application of recent technology to extend the life of structures and techniques developed to strengthen existing structures (A).