Contribution of Aggressive Drivers to Automobile Tailpipe Emissions under Acceleration and Braking Conditions

A small fraction of the vehicle fleet produces a large ratio of the total mobile source emissions or the total fuel consumption due to different patterns of driving behavior based on driver characteristics. The Next Generation Simulation (NGSIM)—Federal Highway Administration (FHWA) trajectory data were used to compare the driving patterns of drivers under congested and uncongested conditions. Drivers were statistically classified into three groups; aggressive, moderate, and defensive drivers based on degree of strength of pushing pedals: gas pedal or brake. Accelerating and braking events, named as process, were counted, and strength of pushing pedal was measured in each process. In this paper, the measured strength of pushing pedal is named as target operating acceleration. Then, the emissions and the fuel consumption of each vehicle were estimated using the Virginia Tech Microscopic energy and emission model (VTMicro) model, which consequently provided the comparison of the emissions and fuel consumption of each driver group. The comparative statistical analyses indicate that aggressive drivers, who frequently used stronger acceleration pedal than other drivers, emitted more hydro carbon (HC), carbon monoxide (CO), and oxides of nitrogen (NOx), particularly under uncongested traffic conditions. The results also indicate that if aggressive drivers change their driving pattern to be defensive, the emissions are expected to decrease by 15.1% of HC, 20.8% of CO, and 16.7% of NOx under uncongested condition.