AASHTO GTDP-2, Guidelines for Traffic Data Programs, 2nd Edition (2009), provides guidance for improving the quality of the traffic information that supports decisions at all levels of the transportation profession. Traffic data programs support the mission of state departments of transportation in ensuring safety and mobility for the traveling public. Traffic data inform capital investment programs and budgets as well as design and maintenance practices. The guidelines are organized in seven chapters, although the preview lists the chapter headings without titles. The work was sponsored by AASHTO in cooperation with the Federal Highway Administration and conducted under the National Cooperative Highway Research Program. State DOT traffic monitoring staff and data program managers can use the guidelines to structure and operate their traffic data collection programs.