RECENT GEOMETRIC DESIGN RESEARCH FOR IMPROVED SAFETY AND OPERATIONS

This synthesis report will be of interest to roadway geometric design, safety, and operations engineers, researchers, and managers. It reviews and summarizes selected geometric design research published during the 1990s, particularly research with improved safety and operations implications. Information for the synthesis study was collected using an extensive literature review and analysis. A short survey of U.S. transportation agencies was also used to gather additional published information and to identify projects that may not have been included in national databases. In part, the incentive for this study was for an updating of the American Association of State Highway and Transportation Officials' "A Policy on Geometric Design of Highways and Streets," more commonly referred to as the Green Book. The results of this review are presented in agreement with the primary sections of the Green Book; that is, design controls and criteria, elements of design, cross sections, intersections, and interchanges.