Estimation of Dynamic Traffic Densities for Official Statistics

Traffic density is one of the important variables to identify traffic states. Traffic management and traffic control require real-time estimation of traffic density as an input for large spatial and temporal coverage of the road network. Statistics Netherlands as a national data collection institute publishes quantified traffic data, among others to support policy makers. In this paper, we aim to validate the usage of GPS information for traffic statistics. The density definition is applied for modelling, and by combining loop detector and GPS data we take the advantages of both data sources. However, the adoption of GPS data is seriously hampered by the fact that few vehicles are equipped with GPS transponders. GPS-collected data thus represent only a limited part of the whole traffic for a delineated area and specific time slots. In our model, travel time of GPS vehicle is an essential concept to get the time boundary of density measurement. Finally, the estimated dynamic density is scaled up to the whole road network to be used for official statistics. GPS data collection has the marked advantage that traffic data are captured automatically at highly frequent rates. As such, it provides dynamic information and offers opportunities to reduce administrative burdens. Furthermore, GPS data collection opens the door to other relevant application areas.