Beginning at an introductory level, this text explores the principles and applications of the design provisions for highway bridges using the new LRFD (Load and Resistance Factor Design) AASHTO code. Combining all the basic information into a single source, it covers bridge loads, load distribution, strength and serviceability, limit states, calculation of load carrying capacity for girder bridges (steel girders, composite steel girders, reinforced concrete T-beams, prestressed concrete girders, various wood bridges), evaluation of existing bridges, effect of corrosion, and fatigue.