The influence of variable message signs on en-route diversion between a toll highway and a free competing alternative

In the field of road transport, Advanced Traveller Information Systems represent a relevant tool to manage road traffic, improve drivers' utility and make a more efficient use of transport infrastructure. Due to the growing sources of en-route information available nowadays, it is crucial to understand better its influence on drivers' behaviour, particularly with regard to route choice. Previous research in this field has mainly focused on the provision of en-route information in toll-free environments. However, few researches have explored its influence when a tolled alternative is available. This paper is aimed at exploring the influence of variable message signs (VMS) information on drivers' route choice, made between a free highway and a competing tolled alternative. To that end, we develop a binary logit analysis based on empirical data from the metropolitan area of Madrid, Spain. Results show that the type of information provided to drivers through VMS panels significantly influences their route choice when one of the alternatives is tolled. Furthermore, some combinations of messages, such as adding travel time estimates together with incident messages, greatly increase the diversion rate to the tolled route. The research also offers evidence that the influence of the information provided changes according to the type of day, which may be related to traffic conditions, and to the different types of user characteristic of weekday and weekend mobility.