Drivers’ Response to In-Vehicle Route Guidance Information Systems: An Experiemnt with a Mock-Up Guidance System.

The paper reports an exploratory study, using an unusual technique to investigate drivers' response to in-vehicle route guidance information systems. Eighteen drivers were recruited, and asked to make a series of three trips in an unfamiliar area. Each driver was given turning advice, via a speech synthesiser, on one of these trips. This advice was based on average traffic conditions for the time of day. Unbeknown to the drivers, the advice was in fact triggered by the experimenter, who was riding as a back-seat passenger. Details were kept of times and routes taken with and without guidance, and with different levels of network familiarity. Records were also kept (using questionnaires and video and audio recording) of planning and route-following strategies.

As expected, both receipt of guidance and even very rudimentary network familiarity resulted in reduced journey times, and routes closer to the guidance recommendations. The study indicated that factors including the directness of possible routes, their perceived complexity, and familiarity all affect route choice, but to different extents for different individuals and under different circumstances. Error was shown to be important in determining the route actually followed when guidance was withheld. The study showed that giving in-vehicle guidance using the mock-up technique described is practicable, and does influence drivers' route-choice and route-following behaviour. A possible future study is outlined, aimed at identifying the determinants of the drivers' level of compliance with advice when they believe that advice is based on real-time traffic information.