This report documents the testing of a piezo-electric cable weigh-in-motion (WIM) truck scale. The equipment tested was developed by the French national laboratory, Laboratorie Central des Ponts et Chausees. Tests were made on the accuracy of the system's static weight estimates, its estimates of vehicle speed, and its classification of vehicles. Speed and vehicle classification estimates were quite good. Weight estimates did not meet the proposed HELP system specifications. The standard deviation of the difference between WIM and static gross vehicle weights was approximately 20 percent.
Tests were also performed to examine the effects of tire pressure, speed and lane position on the voltage output of the cable. Of these variables, tire pressure was determined to most highly effect cable voltage output. Reduction of tire pressures from 105 psi had a statistically significant effect on cable voltage output.