Evaluation of velocity fields via sparse bus probe data in urban areas

The goal of this paper is to investigate how sparse public transport data such as bus data might be used in evaluating congestion in urban areas and in providing better information for road users and traffic managers. With this aim we use the well known concept of a velocity field and, building on our previous work, we specifically show how velocity fields can be usefully reconstructed from sparse bus data. Buses provide good coverage of cities and, increasingly, are being equipped with satellite navigation devices and monitored in order to display their predicted arrival times to bus passengers. We have had access to a wealth of bus data for the city of Cambridge, England for some years. We describe these bus data and show how its specifics may be used in conjunction with other sources of data, such as OpenStreetMap, in order to reconstruct information on transport traffic flow dynamics. Finally, we consider examples in which we compare our knowledge of the traffic regimes with the outputs of the technique presented.