TRB\'s National Cooperative Highway Research Program (NCHRP) Synthesis 431: Practices to Manage Traffic Sign Retroreflectivity includes examples of practices that illustrate how different types of transportation agencies might meet federal retroreflectivity requirements for traffic signs.NCHRP Synthesis 431: Practices to Manage Traffic Sign Retroreflectivity
TRB\'s National Cooperative Highway Research Program (NCHRP) Synthesis 431: Practices to Manage Traffic Sign Retroreflectivity includes examples of practices that illustrate how different types of transportation agencies might meet federal retroreflectivity requirements for traffic signs.