An evaluation of medium range "advance information" in route-guidance displays for use in vehicles

Methods of presenting route guidance information to drivers are compared. Field trials are conducted, with each of 16 subjects undertaking two driving conditions, each on a different route, one with visual guidance information only, and the other with both visual and auditory information. Half the subjects immediately after completing a manoeuvre are briefly given advance information messages warning them of the distance to, and nature of the next turn from the road ahead. Perceived mental workload, frequency and duration of glances to the display, and subjective views are measured. The presentation of visual and auditory information is the preferred mode, reducing both mental workload and time spent looking at the display. Advance information helps in the navigation task, but does not reduce the glance frequency or duration to the guidance display.