Despite the lower traffic volumes, nearly 50 percent of America's fatal motor vehicle crashes occur at night. A contributing factor to the higher fatality rate at night is the reduced ability of motorists to be informed by visual cues. Therefore, motorists often rely on traffic control devices (TCD) under dark conditions for information, warnings, and guidance. This study focused on the visibility of traffic signs under dark conditions.;The new MUTCD standards on traffic sign retroreflectivity have been promulgated to improve nighttime driving safety on all roads open to public travel. This includes roads under the jurisdiction of local road agencies which may lack the resources such as management systems, money, and personnel to comply with these new standards. To assess the impact of the new MUTCD minimum retroreflectivity levels on local road agencies in West Virginia, the current state of traffic sign management practices at the local agency level was determined via survey. Knowing the state of traffic sign management practices in the state of West Virginia, it was then possible to design a case study to assess the effort needed to effectively comply with the new MUTCD traffic sign retroreflectivity standards.;Additionally, this thesis presents a theoretical model for predicting observed light intensity from traffic signs. Ultimately, the model could be used to determine traffic sign size, sheeting material and location to maximize retroreflectivity at critical distances at which motorists are safely and effectively informed. The observed luminance model is a function of the target traffic sign size and sheeting material, the vehicle headlamp intensity pattern, and the horizontal, vertical, and lateral offsets between the motorist's eye, each respective vehicle headlamp, and the target traffic sign.
展开▼
