American Human Factors Research
on In-vehicle Navigation Systems

Paul Green


This report emphasizes route guidance. European and Japanese research, which is extensive and significant, will be covered elsewhere. Critical research includes the Cross and McGrath work on maps, FHWA-funded research on ERGS, studies by Wierwille and his colleagues of the ETAK navigator, studies by Gatline and Davis on in-vehicle audtiory systems (Back Seat Driver), and comparisons of auditory and visual systems by Streeter and Walker. The following are the main findings:

1. Route guidance maps should be oriented heading up. It may be beneficial to
show both the current heading and the four cardinal directions.
2. For ordinary route guidance (well-spaced cross and T intersections, light to
medium traffic), instructions should be simple. ("Turn left at the next intersection,"
not "The next three streets are... When you get to ..."). More complex situations
(heavy traffic, rapid turns in succession) have not been examined.
3. Visual and auditory route guidance systems are about equal in usability.
Simultaneously providing guidance in both formats may not enhance usability.
4. Of the measures proposed to evaluate visually based navigation systems, eye
fixations and navigation errors seem to be the most sensitive to design differences.
5. Missing in the literature are theories that explain why differences occur, studies of
untrained users, and studies of elderly drivers.

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