The use of wider longitudinal pavement markings.

Over the past two decades, as more knowledge has been gained about driver visibility needs and the aging driver population trends, some highway agencies have begun to use longitudinal pavement markings that are wider than the 4-inch minimum for standard centerline, edge line, and/or lane line applications. The overall goal of this study was to identify information pertaining to the use of wider markings by highway agencies in the United States, Canada and worldwide and combine with the technical literature to provide a comprehensive report detailing the use and benefits of wider markings. Research activities included surveys and reviews of technical literature. A survey was administered to roadway agencies in the United States and Canada in Spring 2001. This survey revealed that a number of these agencies are using wider pavement markings, although levels of implementation and reasons for using them vary. A separate but similar survey was administered to highway personnel worldwide. A review of the research literature has identified five main methods for evaluating the effectiveness of wider pavement markings. Traditional measures of effectiveness have centered on crash evaluations and service life evaluations mainly because the results can readily be used in benefit/cost evaluations. Unfortunately, conclusive crash reduction or improved service life data does not exist in the literature or within highway agencies. Evidence has suggested that because conclusive benefit/cost data are not obtainable, highway agencies and researchers alike are turning to indirect (or implied) safety measures to justify the use of wider markings. These indirect measures include: driver opinion surveys/comments, visibility measures, and "intermediate" or "surrogate" safety measures. Although very little research exists, the available scientific evidence suggests that the greatest benefit that wider markings may provide is improved peripheral visibility, which is related to primary driving tasks such as lane keeping. This paper presents the survey results and a critical review of the literature regarding wider pavement markings in the United States, Canada, and worldwide. Conclusions and suggestions have been made as to the use of wider markings by highway agencies and future research endeavours.