THE NEW AASHTO METRIC POLICY ON GEOMETRIC DESIGN OF HIGHWAYS AND STREETS

The American Association of State Highway and Transportation Officials (AASHTO) is revising "A Policy on Geometric Design of Highways and Streets," also referred to as the "Green Book" in the transportation field. The "Green Book" is undergoing a conversion from English to metric units, which was necessitated by the need to comply with a federal law requiring that each federal government agency begin using the metric system in all procurements, grants, and other business-related activities. This article reviews the major revisions to the "Green Book" and summarizes the changes to various chapters.