Evaluation of Road-Sign Geometry Parameter Space Using Exact Roadway Geometry Output Computer Model

Most reflective sheeting specifications were developed when glass-bead retroreflectors were the norm. Micro-prismatic retroreflective sheeting is now become wide-spread and specifications are being revised to accommodate this newer technology. Microprismatic retroreflective sheeting is not as rotationally symmetric as glass-bead sheeting and so greater care in performance specifications is needed. This paper analyzes a range of retroreflective geometries that will occur on the road through the use of the ERGO (Exact Roadway Geometry Output) program. Using this approach, the roadway geometry parameter space can be mapped and reasonable limits and testing may be applied to retroreflective sheeting.