CALIBRATION OF WEIGH-IN-MOTION SYSTEMS. VOLUME I: SUMMARY AND RECOMMENDATIONS. FINAL REPORT

The objective of this study has been to develop relationships between pavement roughness and weigh-in-motion (WIM) system measurement error for individual axles, tandem axles, gross weight and axle spacing. The dynamic weight measured by a WIM scale is determined by the dynamic response of the vehicle system to the pavement roughness. A dynamic simulation model was formulated and used to study the important parameters which affect tire/pavement dynamic force. A series of tests were conducted at three inservice WIM sites in Nevada to determine the relationship between WIM measurement error and vehicle factors including (1) cab type, (2) trailer type, (3) configuration, (4) suspension system type, (5) speed, and (6) roughness. A second series of tests were conducted using two vehicles and instrumented to measure dynamic tire/pavement force. An empirical relationship has been developed to predict axle and gross weight weighing error as a function of pavement roughness. A procedure is outlined to calculate pavement smoothness requirements for WIM installations to achieve specified accuracy levels. An example is included. The other volume in this two-volume series is FHWA-RD-88-129, Calibration of Weigh-In-Motion (WIM) Systems, Volume II: Final Report.