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INTRODUCTION

The compilation of these specifications began in 1921 with the organization of the Committee on Bridges and Structures of the American Association of State Highway Officials. During the period from 1921, until printed in 1931, the specifications were gradually developed, and as the several divisions were approved from time to time, they were made available in mimeographed form for use of the State Highway Departments and other organizations. A complete specification was available in 1926 and it was revised in 1928. Though not in printed form, the specifications were valuable to the bridge engineering profession during the period of development.

The first edition of the Standard Specifications was published in 1931, and it was followed by the 1935, 1941, 1944, 1949, 1953, 1957, 1961, 1965, 1969, 1973, 1977, 1983, 1989, and 1992 revised editions. The present sixteenth edition constitutes a revision of the 1992 specifications, including those changes adopted since the publication of the fifteenth edition and those through 1995. The constant research and development in steel, concrete, and timber stmctures practically dictates the necessity of revising the specifications every few years, and the 1996 edition continues this trend.

Interim Specifications are usually published in the middle of the calendar year, and a revised edition of this book is generally published every 4 years. The Interim Specifications have the same status as standards of the American Association of State Highway and Transportation Officials, but are tentative revisions approved by at least two-thirds of the Subcommittee on Bridges and Structures. These revisions are voted on by the Association Member Departments prior to the publication of each new edition of this book, and if approved by at least two-thirds of the members, they are included in the new edition as standards of the Association. Members of the Association are the 50 State Highway or Transportation Departments, the District of Columbia, and Puerto Rico. Each member has one vote. The U.S. Department of Transportation is a nonvoting member.

Annual Interim Specifications are generally used by the States after their adoption by the Bridge Subcommittee. Orders for these annual Interim Specifications should be sent to the Publication Sales Office of the Association at P.O. Box 967 16, Washington, D.C. 20906-6716. To order by phone call 1-800-231-3475. You can also order online by visiting our website at www.transporation.org.

The Standard Specijîcations for Highway Bridges are intended to serve as a standard or guide for the preparation of State specifications and for reference by bridge engineers.

Primarily, the specifications set forth minimum requirements which are consistent with current practice, and certain modifications may be necessary to suit local conditions. They apply to ordinary highway bridges and supplemental specifications may be required for unusual types and for bridges with spans longer than 500 feet.

Specifications of the American Society for Testing and Materials, the American Welding Society, the American Wood Preservers Association, and the National Forest Products Association are referred to, or are recognized. Numerous research bulletins are noted for references.

The American Association of State Highway and Transportation Officials wishes to express its sincere appreciation to the above organizations, as well as to those universities and representatives of industry whose research efforts and consultations have been most helpful in continual improvement of these specifications.

Extensive references have been made to the Standard Specifications for Transportation Materials published by the American Association of State Highway and Transportation Officials, including equivalent ASTM specifications which have been reproduced in the Association's Standard Specifications by permission of the American Society for Testing and Materials