USE OF SUPPLEMENTAL PLAQUES TO IMPROVE EFFECTIVENESS OF WARNING SIGNS

The use of sign plaques to supplement the messages of a standard sign is a well-established practice. Guide signs make wide use of this practice through the use of cardinal direction and arrow markers. However, the use of supplemental plaques with warning signs is primarily limited to the Advisory Speed Plate and a few miscellaneous plaques. The described research evaluates the effectiveness of using supplemental plaques with standard warning signs to improve driver comprehension of the warning message. Driver comprehension of railroad and pedestrian crossing signs is evaluated with the standard sign alone and with supplemental plaques with arrow and distance markers. The results of driver surveys indicate that supplemental plaques improve driver understanding of the warning message. The research results include recommendations for using supplemental plaques with warning signs to indicate the distance to a hazard, the length of the hazard area, the location of the hazard, recommended driving responses for the hazard, and miscellaneous information. Other recommendations are suggested for the use of warning signs related to railroad and pedestrian crossings.