WIM Technologies

OBJECTIVES: The objectives of this study are: 1) to review the current Weigh-in-Motion (WIM) technology, 2) to evaluate the current calibration procedures, 3) to evaluate the stability of current calibration equipment, 4) to recommend calibration technique and equipment types. BACKGROUND: Traffic data are recognized as a key data element or feature for the analysis of pavement performance. Although there are several types of automatic traffic data collection devices, WIM technology has so far provided the most detailed information on axle loads. The collected accumulative axle loads can be used to build a load spectrum and used for mechanistic pavement analysis. In the new pavement design guide under way, the 2002 Guide for Design of New and Rehabilitated Pavement Structures, the axle load spectrum is a necessary input. Although the data collected by WIM is important, some calibration issues have been raised on this type of equipment in Kentucky and other agencies. The calibration problem has caused unstable weight values and misclassified vehicles, which impair the usage of the valuable traffic load data. The Kentucky Transportation Center is undertaking a WIM calibration study in a small scale. The results of this study will be incorporated in this new study. Upon completion of this study, a better calibration procedure will be developed and the potential of WIM technology can be fully us~ ' FY 2006 ACCOMPLISHMENTS: Work has continued to evaluate the updated WIM calibration procedures. Data collected in 2004 and 2005 has been analyzed to evaluate the effects the new calibration process has on calculated ESAL factors. Tests have also begun to evaluate the feasibility of using portable systems to collect WIM data, two tests sites have been established and the data has been collected to evaluate the accuracy and repeatability of the systems. FY 2007 PROPOSED WORK: Review ofthe portable systems will continue and recommendations will be made regarding their potential use in the statewide data collection program. A scope of work will also be developed and initiated to allow for the Transportation Center to collect and process all WIM: data, while the Division of Planning would maintain and installed the data collection equipment. PROJECTED COST THROUGH FY 2006: PROGRAMMED COST FY 2007: TOTAL ESTIMATED COST: $198,000 $ 20,000 $225,000