Another area of research is user responses to pricing measures and the impact on transport, the environment and the economy.
Few studies have been carried out on whether the complexity involved in highly differentiated pricing schemes based on the social marginal cost (SMC) principle will lead to correct estimation of the price to be paid and, based on this, will generate the desired user responses.
Future research may analyse the factors and dimension of infrastructure charges (e.g., time variability versus spatial differentiation) that make one price signal more complex than others.
Furthermore, research may investigate road charges since this is politically relevant in terms of analysing whether road charging policies are likely to achieve the desired outcome.