The Assessment of Guide Sign Informational Load

Abstract

The informational load of highway guide signs was measured in laboratory experimentation by having subjects view projected highway signs and choose the highway lanes leading to preassigned destinations. The informational load was measured in terms of response times and errors. Subjects were able to very quickly select the proper lane when they viewed common freeway signs and fictitious signs with as many as eight possible destinations. The inclusion on the sign display of unfamiliar destinations and nonguidance information did not appreciably slow subjects' responses. When the destination was not on the sign, subjects had to make navigational decisions, relating sign information to what they knew about the routes. The associated response times were significantly longer than when scanning alone was required. The findings are interpreted in terms of their implications for the design of highway signs.