AASHTO ATG-4, AASHTO Transportation Glossary, 4th Edition (2009), updates and revises the 1983 Transportation Glossary and the unpublished 1998 edition. The glossary covers terminology for the highway, air, rail, water, and transit modes of transportation. The largest additions in terminology were made in bridge and drainage subjects. In addition to terms and definitions drawn from the 1998 glossary and supplementary sources, the publication includes lists of organizational acronyms and abbreviations and references to other glossaries. A shared vocabulary supports communication across transportation agencies and modes. Agency staff, writers, and editors can use the glossary as a standard reference for transportation terms.