Now with newly updated seismic and foundation specifications. This major step in improved bridge design and more accurate analysis is expected to lead to bridges exhibiting superior serviceability, enhanced long-term maintainability, and more uniform levels of safety. This edition includes newly updated foundation specifications, as well as updates throughout. Based on the load and- resistance factor design philosophy (LRFD), this book is the result of a five-year research effort under AASHTO's National Cooperative Highway Research Program (NCHRP) Project 12-42, and a continued effort through AASHTO technical committees. Since the 1st edition was published in 1994, the provisions have continued to be updated and improved based on continuing research and the experience of the user community. The new specifications have been systematically tested in trial designs and have now been implemented by all 50 states, with 48 states fully implemented. As of October 2007, the LRFD design code will be mandated by FHWA for all state projects using federal funding. As of 2010, it will apply to all state bridges regardless of funding and to local bridges using federal funding. Supersedes all previous editions and interims. The single-user CD-ROM contains both the standard and metric editions of the AASHTO LRFD Bridge Design Specifications 4th Edition and is available with the book.