Influence of vehicle speed on dynamic loads and pavement response

Weigh-in-motion systems have been used extensively to measure dynamic loads imparted by traffic vehicles. One of the major uses of these load data is to evaluate the equivalent single-axle loads (ESALs) generated by each load level. The cumulative ESALs are then used in the design or rehabilitation procedures, or both, for the existing road. In situ pavement response parameters, such as the strains at the bottom of the asphalt concrete layer, can also be used to evaluate ESALs. The findings of a research program aimed at evaluating the effect of vehicle speed on the measured dynamic loads and pavement response are documented. The data were measured through a full-scale field experiment. The analyses of the data indicated that vehicle speed has a significant effect on both the measured dynamic loads and the actual response of the pavement system. However, the effects of vehicle speed on dynamic loads and pavement response are not identical. For example, higher vehicle speed generates higher dynamic loads, whereas the strains at the bottom of the asphalt concrete layer are significantly reduced as the speed increases. This discrepancy has been shown to have a great impact on the final design of the pavement system.