The fleet composition on the Dutch roads relevant for vehicle emissions

The average emission per vehicle on a particular road depends on the fleet composition on the road. From the Dutch Pollutant Release and Transfer Register (PRTR) there is an interest in these variations and the way they affect the total emissions of road transport in the Netherlands. The PRTR has commissioned this study to update the fleet composition (per road) and road-type distribution (per vehicle) for the emission factors used for national emission reporting and air quality modelling in the Netherlands. The past assumptions regarding the road-type distributions of different vehicles categories is based on a study from 2010'. Current study is meant to update these assumptions including changes in the vehicle fleet, as seen on the road in 2016. In September 2016 fifteen licence plate cameras collected each two weeks of data in order to establish the typical fleet composition on the different Dutch roads: city, rural and motorways. The licence plate scans are the best way to determine the fleet composition on a particular road. For the vast majority of vehicles from the licence plate information the technical data of the vehicles can be recovered from the RDW (road authority). This data is used, together with the total mileages of each of the vehicle categories as supplied by the Bureau Statistics Netherlands (CBS) to determine the representation of the different vehicle categories on the different roads. Both the age of the vehicles and the fraction of diesel and heavy duty vehicles affect the emissions at that location. The average emission based on the average fleet composition, based on the total mileages alone, does not fully suffices for an accurate determination of the vehicle emissions.