GNSS-based Road User Charging

The last few years have seen a rapid growth of applications based on positioning information provided by satellite positioning systems. In transport management and control, satellite positioning has proven to be the most promising means for spatial location data collection. With the GPS modernisation programme well underway, and the recent developments of the Galileo project, even more GNSS-based applications are to be expected in the future. One such GNSS-based application is the use of position and velocity information as the prime input to a road user charging (RUC) scheme. However, navigation in urban environments raises a number of problems. Most important are the difficulties related to signal obstruction by features such as tall buildings, urban canyons, bridges and trees, as well as the effects of multipath caused by signal reflections from buildings and other vehicles. Given the inevitable limitations of road trials, the use of simulation modelling to assess the present and future satellite positioning systems' performance to support urban RUC seems indispensable. The main objective of the research undertaken at the University of Nottingham Institute of Engineering Surveying and Space Geodesy (IESSG), and the Nottingham Centre for Infrastructure (NCI), was to develop a tool to simulate GPS for Satellite Positioning-based Road User Charging (SPRUC). In this regard, an existing GPS simulator was modified to rectify one of its major weaknesses, namely the inability to address properly the change in non-static GPS measurements with respect to changes in built environment. For this purpose, state-of-the-art Geographic Information Systems (GIS) software was used to complement the simulator, and consequently a seamless interface between the two software has been developed. Finally, in order to provide a prime input to the simulator, field tests have been undertaken and significant amounts of GPS data were collected. Statistics were also derived for positioning accuracy and signal availability so that the results from the simulation modelling can be validated against those from the undertaken road trials.