Assessing the environmental impact associated with different trip purposes

We examine how trips with diverse motivations vary in their spatio-temporal characteristics and result in different impacts on the environment. An integrated model chain is used includes an activity-based traffic demand model, an emission model and a pollutant concentration module. The model setup is applied to the northern region of Belgium and analysed for NO2, an important transport-related air pollutant. The results demonstrate that not every vehicle kilometer has the same impact on the environment in terms of emissions and concentration increases. We find that the highest concentration increase per kilometer is produced by work-related trips. Trips for shopping purposes and services produced the lowest marginal concentration increase. The difference between the highest and lowest marginal concentration increases is about 40%. Important explanatory factors include the time of day when a trip is made as well as vehicle type and speed.

► Vehicle emissions are determined largely by the vehicle type and the vehicle speed.
► Marginal concentration increases depend on the time of day.
► Not every trip motive causes the same environmental impact.
► Difference between the highest and lowest marginal concentration increases is 40%.