DEVELOPMENT OF MINIMUM TRAFFIC SIGNRETROREFLECTIVITY LEVELS IN THE U.S. ANDIMPLEMENTATION STRATEGIES

摘要

The purpose of this paper is to describe the background and current status regarding therndevelopment of updated minimum in-service retroreflectivity levels for traffic signs in the U.S.rnA summary of the earlier work, conducted in the late 1980s to mid 1990s, is provided along withrndescriptions of the relevant validation work. Related events occurring in the late 1990s arerndescribed and shown how, when combined with the assumptions and limitations of the earlierrnminimum retroreflectivity research, they resulted in a need for updated minimumrnretroreflectivity levels. The research related to the updated minimum retroreflectivity levels isrnsummarized. A brief description of a second round of national minimum retroreflectivityrnworkshops is also provided. The most recent set of recommended minimum retroreflectivityrnlevels for traffic signs is presented along with a description of the current U.S. rule-makingrnefforts. Finally, a discussion is also included concerning the implementation strategies that havernbeen developed for agencies to consider using in order to manage their signs in terms ofrnmaintaining minimum traffic sign retroreflectivity levels.