Evaluation of driver response to road user charging systems

Road user charging is uniquely able to manage demand for car use and to raise revenue to finance other measures. Most studies have assumed that charges would be levied at points, or possibly based on distance. However, following proposals for Cambridge the idea of charging in real time, based on time spent travelling or in congestion, has emerged. The technologies for all of these are under development, but those for cordon pricing are currently less complex. There has been a widespread reluctance to pursue real-time charging both because travellers may make sub-optimal decisions, since they will not know the charge in advance, and because drivers may take risks to reduce the charge. These concerns were highlighted in an assessment of the alternatives against Smeed´s criteria. However, recent research has shown that, provided that travellers perceive the charges similarly, congestion-based and time-based charges can have a far greater impact on congestion than point or distance charging.