Part of the research program of the Transport and Road Research Laboratory in the United Kingdom is the study of road transport problems in developing countries. The unit that specializes in this work has carried out an assessment of a new design of timber bridge. It is a truss type made from prefabricated panels and is appropriate for use in countries that need low-cost bridges, but have only a supply of relatively small-section timber. The design is now being developed and promoted in Honduras, Madagascar, and other countries by the Timber Research and Development Association under sponsorship by the United Kingdom and United Nations Industrial Development Organization.

There are few areas of the world that are not now open to road transport. Its importance in the developing world has increased to the point where the economic and the social order are dependent on it, as they are in the western world. The creation and maintenance of a road network is extremely costly for countries that have little to export, so they are obliged to use as much as their own indigenous resources as possible, both in the road pavements and in the bridges. Th is has led to a variety of different bridge designs using different materials around the world. The Chinese are known for their concrete arch bridges. Several Ba iley-t ype steel frame bridges still exist in areas whe re they were used as temporary bridging by armies in times of war. Timber bridges are found everywhere, but the type of timber available and the ability of the constructors have led to the development of different types of timber structure. The most primitive (and still the most common) is the simple beam, which can take the form of a pedestrian bridge or may be used in multiple forms as a highway bridge.