Drivers' awareness of traffic sign information
Field and laboratory experiments were carried out to investigate drivers' levels of awareness of traffic sign information under normal driving conditions, and to validate the laboratory technique. The reliability and sensitivity of the experimental measure (RSI—the level of reported sign information) were sufficient to show significant effects of factors such as sign ‘action potential’, traffic density, type of sign, sign background complexity and sign conspicuity; the dominant factor was sign action potential. Inexperienced drivers exhibited a significantly higher level of RSI (mean of 0·39) than experienced drivers (mean of 0·26).
Sign legibility was poorer in the laboratory and this significantly decreased the level of RSI for verbal signs, relative to field levels of RSI. Also, the effects of rated sign conspicuity were greater in the laboratory. Nevertheless, there was a high level of agreement between laboratory and field results, both in absolute levels of RSI and in the patterns of influence of the various independent variables, and the laboratory method is recommended for future use.