Variations in Axle Weights of Moving Trucks 650515

This paper presents an analysis of axle weight data collected during the performance testing of the Broken Bridge dynamic electronic highway scale. Test results are analyzed by comparing the in-motion axle weights as measured by the Broken Bridge scale with the corresponding static values for an instrumented two-axle test vehicle and for a sample of trucks diverted from an Interstate highway. Analysis of the two-axle test truck data shows that the actual loads applied to the highway surface by the wheels of a moving vehicle vary above and below the static equivalents in a manner that is typical for a specific location and range of speeds. For a random selection of different types of trucks, the variation of dynamic from static axle weight is further affected by axle position (front, second, third, and so forth) and spacing. It is generally concluded that dynamic scales should be used to collect large samples of axle weight data at various locations in the highway system and that such information should be evaluated and used in formulating future pavement design criteria. It is also suggested that further research be conducted in the field of vehicle dynamics to consider the variations in axle loads due to vehicular, driver, and environmental characteristics.