Abstract
In late 2001, the American Association of State Highway and Transportation Officials (AASHTO) published a long-awaited update to "A Policy on Geometric Design of Highways and Streets," commonly known as "the Green Book." Green Book policies guide engineers in designing the physical layout and dimensions for safe and efficient highways. The 2001 version--900-plus pages in an 8.5-in. x 11-in. softcover format--is a comprehensive, substantive update of the 1994 edition. In this article, three researchers involved in the revisions provide an overview of the new policies, specifications, and terminology.