An investigation into the effect of heavy vehicles on traffic flow during congestion is presented in this paper. Several factors that are thought of as determinants of this effect were considered in the investigation. Empirical data and microscopic traffic simulation were used in the analysis. A passenger car equivalency factor derived from queue discharge flow was used as an indicator of heavy vehicles' effect. While stud y results suggest some similarities between free-flow and congested traffic regimes concerning heavy vehicles' effect, some important differences exist due to the different mechanisms that govern heavy vehicles' performance in the two regimes. Also, lane-use restriction and the location of bottleneck relative to upgrades were found to have considerable influence on heavy vehicles' effect during congestion. (a).
Abstract