MODELLING DRIVER RESPONSE TO VARIABLE MESSAGE SIGNS FOR INCIDENT MANAGEMENT

One of the most promising uses of variable message signs (VMSs) is in the area of incident management. If drivers' response, in terms of probability of diversion, to various VMS messages can be predicted, it may be possible to influence drivers' route-choice behaviour by the use of appropriate messages in order to achieve an 'optimum diversion rate'. This could be used as a valuable traffic management tool during incidents: a simulation model can estimate the 'optimum' diversion rate for any incident scenario, then the appropriate message content can be selected and displayed to generate the required diversion response from motorists. This paper presents the findings of our research in support of the above hypothesis. An interview survey was conducted in the Sydney Metropolitan Region to collect information on driver response to a range of VMS messages. Statistical analysis of the data was carried out and a route-choice model was developed which can be used to predict the diversion rate resulting from various VMS message contents. The VMS-response model was implemented in a microscopic simulation model, SITRAS, and a case study was conducted on a section of the Sydney road network, to demonstrate the benefits of the model in developing and optimising incident management plans. The paper outlines the model development process, presents the findings and conclusions of the case study, and finally it identifies issues for further research.