Impact of road traffic incidents on pollutant emissions

Road transportation is an essential component of the European economy. However, this sector is responsible for the increase of emissions and fuel consumption from year to year. Traffic incidents are one of the main causes of congestion. This paper has the main objective to calculate the consequences in traffic performance, fuel consumption and emissions that result from the occurrence of road incidents, including illegal parking, on an urban street. The case study developed was made on Avenue Dr. Lourenço Peixinho, in Aveiro, Portugal. Some alternatives were studied to avoid these incidents. The methodology was based on the microscopic road traffic simulation model VISSIM and on real data measurements. The results obtained show that incidents are generators of emissions and fuel consumption, since they lead to more aggressive driving modes. It was found that the increase in emissions is primarily due to the incident location. The most critical incidents are those that are close to adjacent lanes, regulated by traffic lights. Pollutant emissions increase while drivers are waiting behind the illegally parked cars to switch to the left lane. During these periods the vehicles are subjected to stop and go situations that lead to an increase in emissions. Depending on the occurring incidents on the lanes, a 60% increase of emissions and fuel consumption can occur.