Vehicle characteristics and load effects of four-lane highway

For vehicle flow on four-lane highway, one of the most typical features is the significant differences in the vehicle distributions and load characteristics among different lanes. These differences exert great influence on the structure responses. WIM (Weight In Motion) system is adopted to obtain traffic data of a four-lane highway and a two-lane highway in Guangdong Province, China. Statistical analysis is introduced for the vehicle distributions and load composition on different lanes, and spatial distribution laws of vehicle flow and load are explored. Based on the analysis, sensitivity of bridge structure to the transverse differences of vehicle flow is discussed. It is indicated that traffic is heavier on the inner lanes with a larger proportion of compact vehicles, while the integral level of vehicle load is higher on the outer lanes. Vehicle load effect extreme value of the bridge structure is the largest on the second outer lane. It is discovered that the measured vehicle load effect values are generally larger than the values calculated by the current Chinese code. This result suggests that the vehicle load models in the current Chinese code are in urgent need of proper modification.