In this research project, the influence of long heavy vehicles on traffic flow at freeway interchanges was analyzed by using the microscopic simulation tool BABSIM. The sample consists of different exit and entrance types as well as a weaving area. The simulation models were calibrated and validated for heavy vehicle percentages between 10% and 15% with data from loop detectors. For each investigation site, simulations were conducted with a percentage of long heavy vehicles of 0%, 1%, 2% and 5% as well as three different scenarios with different proportions of entering and exiting vehicles. Another approach was to compare scenarios in which three regular heavy vehicles were substituted by two long heavy vehicles. For each scenario, ten simulation runs were conducted. The mean traffic breakdown volume was used to estimate the capacity and to compare the different scenarios. Overall, the results of the simulation study indicate that percentages of long heavy vehicles between 1 and 5% of the total traffic volume do not significantly influence the capacity of freeway interchanges. The effects of long heavy vehicles on interchange capacity are in the range of the capacity differences between different interchanges that can be observed in the field even under similar geometric and traffic conditions. (Author/publisher)
Samenvatting