Comparison of Observed Retroreflectivity Values with Proposed FHWA Minimums

Until recently, no federal guidance existed on the retroreflectivity of highway signs, and the replacement policy has been left to the discretion of local officials. FHWA has now published a proposed set of minimum retroreflectivity requirements for traffic signs. The proposed minimum retroreflectivity values published by FHWA were compared with retroreflectivity values observed from signs with ASTM Type III sheeting in the state of Indiana. Research found that approximately 4% of signs scheduled for removal in 2000 or 2001 were below the proposed FHWA minimums. Having different retroreflectivity minimums for different speeds and sign sizes unnecessarily complicates the proposed minimums. Using the single most conservative retroreflectivity value for each color would be sufficient.