American Association of State Highway and Transportation Officials Publications

AASHTO is a nonprofit, nonpartisan association representing highway and transportation departments in the 50 states, the District of Columbia, and Puerto Rico. It represents all five transportation modes: air, highways, public transportation, rail, and water. Its primary goal is to foster the development, operation, and maintenance of an integrated national transportation system.
AASHTO includes specifications, provisional standards, standard test methods, recommended practices, guide specifications, manuals, the Bridge Welding Code, etc.