Impact of Driving Behaviour on Emissions and Road Network Performance

This paper presents findings from a simulation-based comparative evaluation of driving behaviours and their impacts on road safety, environmental quality and network efficiency. Driving behaviour was represented by driver speed, acceleration, lane changing and gap acceptance actions. A fourmode elemental emissions model was used to collect second-bysecond data on fuel consumption and CO₂ emissions. Surrogate measures of safety, expressed in terms of the number of lane changes and severe decelerations, were used to describe the degree of safety in the simulation experiments. Aggressive drivers were found to be 35 times more likely to be involved in a crash on the motorway, and two times more likely to be involved in a crash on the urban network. The results for the motorway simulations also showed that aggressive drivers achieved only a 3.8 percent reduction in travel times (62 seconds on a 26 minute trip) at the expense of 85 percent more lane changes and 332 percent increase in fuel consumption and CO₂ emissions. The reduction in travel times for urban conditions was lower at around 1.6 percent (7 seconds on a 434 second trip) at the expense of 300 percent more lane changes and 138 percent increase in fuel consumption and CO₂ emissions. Sensitivity analysis of the impacts of varying proportions of drivers was also conducted. The results showed that the negative impacts of aggressive driving behaviour outweigh by a factor of three any benefits that can be obtained through reductions in travel times.