Computer-Based Modeling to Determine the Visibility and Minimum Retroreflectivity of Pavement Markings

Abstract

The Federal Highway Administration was mandated by the U.S. Congress to establish in-service levels of minimum pavement-marking retroreflectivity and commissioned research to determine the minimum in-service level from a driver’s point of view. Computer Aided Road Marking Visibility Evaluator (CARVE) was developed and refined to systematically investigate drivers’ visual needs in terms of nighttime pavement-marking visibility and to allow the formulation of minimum retroreflectivity recommendations. The components within CARVE and the methods, algorithms, and equations that are used to determine the visibility distance of a given pavement-marking treatment are presented and discussed. CARVE systematically manipulates the pavement-marking efficiency (ηPM) up and down using a bisecting-search algorithm until the desired minimum required preview distance for selected conditions is achieved. Future expansions of CARVE, or the development of models that supersede it, may require additional research to investigate the wet-weather visibility of pavement markings, the effects of combined treatments consisting of pavement markings and raised reflective markers, and the visibility in inclement weather such as fog and blowing snow.