This manual is designed to be used in connection with the Standard specifications for highway bridges /AASHO/, adopted in 1961. It has been compiled to assist bridge engineers concerned with the proportioning of concrete members for conditions of ultimate loading. The emphasis is placed on design methods for reinforced concrete members whose behavior is limited by the ultimate stage of behavior at ultimate loading. When the safety limits of the materials are considered, the ultimate design method produces superior economy over the working stress design method.