A major step in improved bridge design and more accurate analysis methods, which are expected to lead to bridges exhibiting superior serviceability, enhanced long-term maintainability, and more uniform levels of safety. 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 Project 12-33. The new specifications have been systematically tested in trial designs in bridge design divisions of 14 AASHTO Member Departments. The publication is available in either U.S. or metric versions, or may also be purchased as a two-volume set. For complete information, purchasers should also obtain the 9600 and 1997 Interim Revisions.