scope:

PREFACE: This policy was developed as part of the continuing work of the Standing Committee on Highways. The Committee, then titled the Committee on Planning and Design Policies, was established in 1937 to formulate and recommend highway engineering policies. It has developed A Policy on Geometric Design of Rural Highways, 1954 and 1965 editions, A Policy on Arterial Highways in Urban Areas, 1957, A Policy on Design of Urban Highways and Arterial Streets, 1973, Geometric Design Standards for the National System of Interstate and Defense Highways, 1956 and 1967, Geometric Design Standards for Highways Other Than Freeways, 1969, A Policy on Geometric Design of Highways and Streets, 1984, and a number of other AASHO and AASHTO policy and "guide" publications.

An AASHTO publication is typically developed through the following steps: (1) The Committee selects subjects and broad outlines of material to be covered. (2) The appropriate subcommittee and its task forces, in this case the Subcommittee on Design and its Task Force on Geometric Design, assemble and analyze relevant data and prepare a tentative draft. Working meetings are held and revised drafts are prepared, as necessary, and reviewed by the Subcommittee, until agreement is reached. (3) The manuscript is then submitted for Standing Committee on Highways approval, and then Executive Committee approval. Standards and policies must be adopted by a two-thirds vote by the Member Departments before publication. During the developmental process, comments were sought and considered from all the States, the Federal Highway Administration, and representatives of the American Public Works Association, the National Association of Country Engineers, the National League of Cities, and other interested parties.

Changes in allowable maximum dimensions for truck-trailer combinations, the revision of the Highway Capacity Manual in 1985 and other developments subsequent to the 1984 edition prompted AASHTO to again update this policy.

Following the procedures outlined above, the Task Force on Geometric Design met in 1987 to begin the work that has resulted in this current edition. It is anticipated that a continuing effort will be maintained by the Subcommittee on Design to keep the policy up to date with future developments in geometric design.