Development of minimum traffic sign retroreflectivity levels in the U.S. and implementation strategies.

The purpose of this paper is to describe the background and current status regarding the development of updated minimum in-service retroreflectivity levels for traffic signs in the U.S. Related events occurring in the late 1990s are described and shown how, when combined with the assumptions and limitations of the earlier minimum retroreflectivity research, they resulted in a need for updated minimum retroreflectivity levels. The research related to the updated minimum retroreflectivity levels is summarized. A brief description of a second round of national minimum retroreflectivity workshops is also provided. The most recent set of recommended minimum retroreflectivity levels for traffic signs is presented along with a description of the current U.S. rule-making efforts. Finally, a discussion is also included concerning the implementation strategies that have been developed for agencies to consider using in order to manage their signs in terms of maintaining minimum traffic sign retroreflectivity levels. (Author/publisher) For the covering entry of this conference, please see ITRD abstract no. E213531.