On-road CO2 and NOx emissions of a diesel vehicle in urban traffic

Light-duty diesel vehicles are a significant contributor to urban air pollution. This study aimed to investigate the variation in driving style and emissions based on traffic conditions, route features and route familiarity using 30 drivers. Driving styles were assessed using acceleration, relative positive acceleration and velocity × positive acceleration and it was found that approximately 42% of drivers were aggressive on both trips. The difference between the highest and lowest emitting drivers was observed to be a factor of 5.9 for nitrogen oxides (NOx) and 1.56 for carbon dioxide (CO2). A linear relationship between cumulative NOx emissions and cumulative CO2 emissions was found at the individual driver level. The study also detected several emission hotspots resulting from certain route features. This study will contribute to: 1) understand how driver behaviour, traffic conditions, route familiarity and route features contribute to emissions; 2) develop predictive emission models; and 3) optimise route characteristics.