Edinburgh Napier University

  Over the past few decades there has been a renewed interest in road pricing. This has come about due to the increasing realisation of the negative effects of unrestrained car use, such as, the impact of congestion on the economy and pollution on the environment, to name a few. In this respect, road pricing offers a mechanism for controlling demand. To date, road pricing has been applied to city centres, sections of motorways, individual lanes, bridges, tunnels to name but a few examples. Charges can also be further refined and varied according to the time of day, day of the week, traffic volumes, vehicle types, vehicle occupancy, etc.
Moreover, the evaluation of transport schemes has become reliant on the careful consideration of all possible outcomes. An important technology which has been developed is traffic microsimulation modelling. This enables transport professionals to replicate by computer simulation the behaviour of individual vehicles within an exact representation of the actual road network. The robustness of microsimulation modelling, nevertheless, depends on the accuracy with which actual traffic behaviour is represented. In the case of road pricing the key element lies in predicting motorist’s behavioural responses when confronted with tolls.
There are various scenarios in which tolls could be applied and some may offer alternative routes, alternative modes, etc. Yet, these all depend on an individual’s willingness to pay to avoid a congested trip that comprises either increased journey times (measured as ‘Value Of Time’) or a more unpredictable journey time (measured as ‘Value Of Reliability’).
The purpose of this research is to advance the modelling of trip-makers behavioural responses to tolls in a PC-simulated environment. The objectives are therefore: (1) to determine the modelling procedure that proves most adequate to the requirements of the modelling of tolls, (2) to establish the necessity of including a VOT and VOR element in the route choice system of a model, (3) to review VOT and VOR values in the literature and to identify the variables that account for different valuations, (4) to assess whether values from literature are applicable to a UK context, and in case they are not (5) to develop a calibrated and validated microsimulation model that can be used in future research to derive UK values. From this modelling exercise, conclusions are derived about the challenges of modelling congested networks with highly variable travel times and its implications in the inclusion of VOT and VOR in simulation. Finally, recommendations for future research are presented based on the findings of this research.