This manual describes the elements, considerations, investigation tools and techniques, and reporting requirements for geotechnical subsurface investigations for transportation facilities. This second edition, which supersedes the 1988 first edition, has been updated to address advancements in geophysical, in situ, and laboratory testing; reliability-based design as codified by the AASHTO LRFD Bridge Design Specifications, 9th Edition; and project delivery methods. These updates are a reference for planning, executing, and using subsurface investigations and geotechnical characterizations in order to design, construct, maintain, and manage assets of transportation facilities. --From publisher