RATIONAL LOOK AT TRUCK AXLE WEIGHT

The load applied by trucks on pavement varies instantaneously due to road roughness, truck speed, suspension type, tire pressure, and other factors. The instantaneous actual (dynamic) load fluctuates above and below the static weight, and the difference can be significant. Current weigh-in-motion (WIM) devices provide a snapshot of the dynamic load spectrum. These measurements can be improved by using multisensor devices to better represent the actual wheel load distribution. The larger the number of sensors in a WIM device, the larger the accuracy in representing the dynamic load spectrum. Multisensor WIM devices can be used to estimate both the mean and the standard deviation of the dynamic wheel forces applied by the tires on the pavement. A larger number of sensors is required to accurately estimate the standard deviation than the number required to accurately estimate the mean. Also, the chance of underestimating the actual standard deviation is larger than that of overestimating the actual standard deviation. Because pavement performance is affected more by dynamic loads than by static loads, dynamic loads could be better used to control the legal load limit, taxation, penalties, and pavement design and analysis. Further research is needed to provide proper implementation procedures and to separate the dynamic forces caused by truck and road factors.