Possible sources of data on drivers' reactions to route guidance are discussed. Field evidence is sketchy and appears likely to remain so for some time. It is argued that an interactive route-choice simulator might provide acceptable substitute data. The design and development of such a simulator, interactive guidance on routes (IGOR), is described; users make a series of journeys through test networks by indicating their desired exit from each junction they reach. At each junction IGOR displays a plan giving traffic conditions, and so on. For some journeys the user has access to a map of the network, guidance advice, or both. The advice system replicates in-vehiclesystems, which advise the driver what exit to take at each junction in order to minimise journey time in the current traffic conditions. To ascertain the effect of variations in the quality of guidance on user response, a "wrong" exit is sometimes recommended. The use of IGOR to collect data under the dedicated road infrastructure for vehicle safety in europe initiative is described and important results are presented. It is observed that acceptance of an item of advice depends on its (objective) quality, the quality of previously received advice, the drivers' knowledge of the network, and on the extent to which advice is corroborated by other evidence. Compliance with advice is a function of its credibility and this in turn depends on past experience, local conditions, and psychological factors. The value of IGOR and its results are discussed. Plans for use and further analysis of the IGOR data are outlined together with some options for further development of the concept. This paper appears in Transportation Research Record No. 1306, In-vehicle Information Systems: modelling Traffic Networks and behavioural Considerations 1991.
Abstract