American Association of State Highway and Transportation Officials

The American Association of State Highway and Transportation Officials (AASHTO) is a standards setting body which publishes specifications, test protocols, and guidelines that are used in highway design and construction throughout the United States. Despite its name, the association represents not only highways but air, rail, water, and public transportation as well. Although AASHTO sets transportation standards and policy for the United States as a whole, AASHTO is not an agency of the federal government; rather it is an organization of the states themselves. Policies of AASHTO are not federal laws or policies, but rather are ways to coordinate state laws and policies in the field of transportation. The American Association of State Highway Officials (AASHO) was founded on December 12, 1914. Its name was changed to American Association of State Highway and Transportation Officials on November 13, 1973. The name change reflects a broadened scope to cover all modes of transportation, although most of its activities are still specific to highways. While AASHTO is not a government body, it does possess quasi-governmental powers in the sense that the organizations that supply its members customarily obey most AASHTO decisions. The voting membership of AASHTO consists of the Department of Transportation of each state in the United States, as well as those of Puerto Rico and the District of Columbia. The United States Department of Transportation, some U.S. cities, counties, and toll-road operators, most Canadian provinces as well as the Hong Kong Highways Department, the Turkish Ministry of Public Works and Settlement, and the Nigerian Association of Public Highway and Transportation Officials have non-voting associate memberships. Some noteworthy AASHTO publications are: A Policy on Geometric Design of Highways and Streets, often called "The Green Book" because of the color of its cover. This book covers the functional design of roads and highways including such things as the layout of intersections, horizontal curves, and vertical curves.