American Association of State Highway and Transportation Officials (AASHTO)
AASHTO is a leading standards development organization that produces technical standards for all phases of highway system development. Their standards focus on the design and construction of highways and bridges, as well as materials, and many other technical areas.
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Popular AASHTO Standards
| Standard Code | Title | Format Available |
|---|---|---|
| AASHTO GDHS-7 | AASHTO Green Book | PDF, Print |
What Are AASHTO Standards?
Founded in 1914, when the United States recognized the need for a unified body to guide the rapidly developing field of road building, AASHTO quickly provided engineering guidance to build reliable and interconnected road networks. Its early work focused heavily on creating standards that would help states coordinate roadway construction and ensure compatibility across state lines.
AASHO played a crucial role in the development of highway engineering as well as shaping national transportation policy. One of its most influential early contributions was its involvement in establishing uniform road design specifications and materials standards, ensuring that roads built in one state could safely and seamlessly connect to those in another.
By the 1970’s, the scope of transportation in the United States evolved beyond highways, and AASHTO encompassed a broader mission that included rail, transit, aviation, active transportation, and other emerging mobility modes. State departments of transportation were increasingly multimodal agencies and — as an established expert in the field — AASHTO began offering standards and guidance across diverse transportation systems.
AASHTO serves as a national forum for state transportation agencies to collaborate, share best practices, and influence federal transportation policy. The organization produces authoritative technical manuals that are widely used by engineers and planners. The most notable documents include the “Green Book: A Policy on Geometric Design of Highways and Streets”, bridge design specifications, and materials testing standards. These documents form the backbone of transportation engineering practice in the United States, ensuring consistency, safety, and reliability in infrastructure design and maintenance.
Today, AASHTO continues to guide the evolution of the world’s transportation system by supporting research, developing standards, and engaging in policy advocacy. Its work helps organizations navigate emerging challenges such as climate resilience, electric vehicle infrastructure, autonomous technologies, and sustainable mobility.
