The American Association of State Highway and Transportation Officials (AASHTO) is a standards setting body which publishes specifications, test

protocols Protocol may refer to: Sociology and politics * Protocol (politics), a formal agreement between nation states * Protocol (diplomacy), the etiquette of diplomacy and affairs of state * Etiquette, a code of personal behavior Science and technology ...

, and

guideline A guideline is a statement by which to determine a course of action. It aims to streamline particular processes according to a set routine or sound practice. They may be issued by and used by any organization (governmental or private) to make ...

s that are used in

highway A highway is any public or private road or other public way on land. It includes not just major roads, but also other public roads and rights of way. In the United States, it is also used as an equivalent term to controlled-access highway, or ...

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.

Purpose

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.

Membership

The voting membership of AASHTO consists of the Department of Transportation of each state in the United States, as well as those of

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and the

District of Columbia Washington, D.C., formally the District of Columbia and commonly known as Washington or D.C., is the capital city and Federal district of the United States, federal district of the United States. The city is on the Potomac River, across from ...

. The

United States Department of Transportation The United States Department of Transportation (USDOT or DOT) is one of the executive departments of the U.S. federal government. It is headed by the secretary of transportation, who reports directly to the president of the United States a ...

has a non-voting associate membership.

Publications

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. * ''Standard Specifications for Transportation Materials and Methods of Sampling and Testing''. * ''AASHTO LRFD Bridge Design Specifications''. This manual is the base bridge design manual that all DOTs use across the US. *
Manual for Assessing Safety Hardware
' (MASH), crash testing criteria for safety hardware devices for use on highways; it updates and replaces NCHRPbr>Report 350
In addition to its publications, AASHTO performs or cooperates in

research Research is creative and systematic work undertaken to increase the stock of knowledge. It involves the collection, organization, and analysis of evidence to increase understanding of a topic, characterized by a particular attentiveness to ...

projects. One such project is the AASHTO Road Test, which is a primary source of data used when considering transport policies and the structural design of roads. Much of AASHTO's current research is performed by the

National Cooperative Highway Research Program The National Cooperative Highway Research Program (NCHRP) conducts research in problem areas that affect highway planning, design, construction, operation, and maintenance in the United States. Spearheaded by the Transportation Research Board (TR ...

(NCHRP) which is administered by the

Transportation Research Board The Transportation Research Board (TRB) is a division of the National Academies of Sciences, Engineering, and Medicine. TRB's mission is to mobilize expertise, experience, and knowledge to anticipate and solve complex transportation-related challe ...

(TRB), a division of the National Academy of Sciences, Engineering, and Medicine. AASHTO re:source, formerly the AASHTO Materials Reference Laboratory (AMRL), accredits laboratories. Accreditation is often required to submit test results to state DOTs. For example, a contract for the construction of a highway bridge may require a minimum

compressive strength In mechanics, compressive strength (or compression strength) is the capacity of a material or Structural system, structure to withstand Structural load, loads tending to reduce size (Compression (physics), compression). It is opposed to ''tensil ...

for the

concrete Concrete is a composite material composed of aggregate bound together with a fluid cement that cures to a solid over time. It is the second-most-used substance (after water), the most–widely used building material, and the most-manufactur ...

used. The contract will specify AASHTO Test Designation T 22, "Compressive Strength of Cylindrical Concrete Specimens," as the means of determining compressive strength. The laboratory performing T 22 will be required to be accredited in that test. AASHTO coordinates the numbering of

Interstate Highway The Dwight D. Eisenhower National System of Interstate and Defense Highways, commonly known as the Interstate Highway System, or the Eisenhower Interstate System, is a network of controlled-access highways that forms part of the National Hi ...

s, U.S. Highways, and U.S. Bicycle Routes.

Standards

Current and withdrawn AASHTO standards include: * AASHTO TP10: Standard Test Method for Determining the tensile strength and temperature at fracture of field or laboratory compacted bituminous mixtures by measuring the tensile load in a specimen which is cooled at a constant rate while being restrained from contraction. * AASHTO T307: Standard Method of Test for Determining the Resilient Modulus of Soils and Aggregate Materials. * AASHTO T321/TP4: Test Standard for Determining the Fatigue Life of Compacted Hot-Mix Asphalt (HMA) Subjected to Repeated Flexural Bending. * AASHTO TP31: Standard Test Method for Determining the Resilient Modulus of Bituminous Mixtures by Indirect Tension * AASHTO TP62: Standard Method of Test for Determining Dynamic Modulus of Hot-Mix Asphalt Concrete Mixtures * AASHTO T321-03/TP8: Test Standard for Determining the Fatigue Life of Compacted Hot-Mix Asphalt (HMA) Subjected to Repeated Flexural Bending

References

External links