An Evaluation of the Safety and Environmental Impacts of Microcars

Abstract

The existence of single-occupancy vehicles (SOVs) in the traffic stream leads to unjustified congestion and shortage in the available parking spaces especially in mega cities. This research analyzes the traffic safety and environmental impacts of using microcars on roads using microsimulation. VISSIM was used to model two case studies: an urban corridor and a suburban expressway in Greater Cairo, Egypt. Safety assessment was performed using surrogate safety assessment model (SSAM) to calculate different surrogate safety measures such as the average Time to Collision (TTC), Post Encroachment Time (PET), Deceleration Rate (DR), and number of lane changes. It was found that the increase in the percentage of microcars on the urban corridor led to a slight improvement in safety measures especially in case of mixed lanes traffic operation. For the suburban expressway, providing exclusive lanes for microcars was found to have a significant positive impact on safety. As for the environmental impacts, vehicles’ emissions were calculated for two scenarios. In the first scenario, it was assumed that the microcars were non-electrical. In that case, the change in the amount of emissions would be attributed to the change in traffic conditions due to the introduction of microcars. In the second scenario, it was assumed that all the introduced microcars were electric. The results of the first scenario showed that the introduction of microcars had led to a large reduction in the total amount of emissions for low and moderate traffic volumes, but it did not have a significant effect on emissions at high traffic volumes on the urban corridor. In the second scenario, it was found that increasing the percentage of microcars on the urban corridor significantly decreased NOx emissions , and that increasing the percentage of electric microcars decreased NOx emissions for the simulated suburban expressway but with a percentage that is less than that on urban roads.