Accident reduction effects of using weigh-in-motion and automatic vehicle identification for mainline bypass around truck weigh stations

Using weigh-in-motion (WIM) and automatic vehicle identification (AVI) technologies may permit trucks with appropriate credentials to bypass the weigh station on the mainline traffic stream. This would reduce the number of disruptions to the mainline traffic stream and reduce the chances that an accident might occur. Characteristics of accidents on road segments around weigh stations [influence zones (IZs)] are examined and compared with those for accidents on similar basic free-way sections [control zones (CZs)]. There were significantly more accidents around weigh stations than on similar basic freeway sections, particularly during operating hours. Similarly, there were significantly more accidents involving trucks in the IZs than in the CZs. A comparison of the number of IZ and CZ accidents during typical operating hours, excluding animal-related accidents, indicated that the CZs had 38 percent fewer accidents than the IZs. This would result in 146 fewer accidents during typical operating hours around the 20 Interstate weigh stations when animal accidents are not included. When animal accidents were included, the reduction was 30 percent. This would reduce the total number of accidents during typical operating hours around the 20 Interstate weigh stations over 10 years by 129. Thus, a maximum reduction of 129 to 146 accidents could be achieved if the IZs were made identical to the CZs. These figures represent the upper limit of accident reductions. A model is developed to predict potential accident reductions around weigh stations at varying levels of WTM and AVI usage. The resulting model is an S-shaped curve, which should approximate the potential accident reductions as a function of percent WIM-AVI usage.