Trrl Lr 910

The laboratory has developed a weighbridge system that records automatically, without interference with the traffic, the magnitude of wheel loads passing over it. The report summaries the results obtained from 30 weighbridges installed, primarily for the purposes of research, at a number of full-scale road experiments and on three motorways. Systematic data have been obtained from some of the more important sites; at others it has proved possible to make only infrequent measurements. Since 1973 the weights and hence the damage factor, of axle of the commercial traffic using motorways and some heavily trafficked trunk roads have risen considerably faster than on other roads. Traffic on the exit road from a refinery and port has been shown to have a greater axle damage factor than any measured motorway traffic. Estimates have been made of the number of axles and the damage factor of the average commercial vehicle using different categories of road. The results have then been combined to give curves for estimating the changes in vehicle damage factor of commercial vehicles on four categories of road between the years 1945 and 2005. Tables are presented of the factors required for the design of a new road, for the prediction of the remaining life of an existing road and for the design of strengthening measures for such a road