TRB’s National Cooperative Highway Research Program (NCHRP) Research Results Digest 305 - Pavement Marking Materials and Markers: Testing the Relationship Between Retroreflectivity and Safety explores the safety impact of pavement markings and markers with their performance, principally measured in terms of their retroreflectivity. The digest summarizes the final report on the project that was published as NCHRP Web-Only Document 92: Pavement Marking Materials and Markers: Real-World Relationship Between Retroreflectivity and Safety Over Time.