In Texas, commercial vehicle safety is increasing in priority due to the rising volume of truck traffic and the disproportionate percentage of crashes and fatalities involving large trucks. One particular safety issue is the visibility of signing and pavement markings at night from a commercial vehicle driver's perspective. Through a nighttime controlled field study, the relationship between vehicle type (passenger car versus commercial vehicle) and sign/pavement marking material was evaluated in terms of the legibility distance of signs and the end detection distance of pavement markings. Additional research issues included investigations among sign type (guide, destination, and speed limit) and age (young, middle-aged, and old). The findings indicate that the commercial vehicle provided statistically longer legibility distances than the passenger car. However, an examination of headlamp illuminance suggests that the headlamp illuminance of the commercial vehicle used in the nighttime controlled field study was higher than the average headlamp illuminance of on-road commercial vehicles. In addition, the type of retroreflective material was found to be a significant factor for the speed limit signs and the pavement markings, but not for the guide signs or destination signs. The relationship between vehicle type and material type was found to be statistically significant only for the speed limit signs. However, the practical difference was small and the legibility distance did not clearly depend on any particular combination of vehicle type and material type.
Abstract