Multiple-Presence Statistics of Heavy Trucks Based on High-Speed Weigh-in-Motion Data

The simultaneous presence of multiple heavy trucks on road bridges causes a higher stress to the structural members of bridges than the presence of a single heavy truck. Truck traffic data acquired using weigh-in-motion systems are typically used to assess the multiple-presence probability for side-by-side and following trucks. A number of high-speed weigh-in-motion (HS-WIM) systems are installed in the Korean Expressway Network to control overloaded vehicles and obtain long-term truck weight data. In this study, the multiple-presence probabilities for following and side-by-side trucks were determined using data from two HS-WIM sites. The correlation probability between the gross vehicle weights (GVWs) of successive trucks was also calculated. To determine the characteristics of heavier truck loads, the multiple-presence probabilities for the overweight trucks, which exceed the legal weight limit, were calculated separately. The analysis of the HS-WIM data showed that the multiple-presence probabilities of the trucks increased with the headway distance of following or side-by-side trucks, and the probability of following truck events was lower than that of side-by-side truck events. The probability of side-by-side truck events increased with the increase of daily truck traffic (DTT), whereas the probability of following truck events was only slightly affected by the DTT. The full correlation probabilities of the GVW for the following and side-by-side trucks were low.