The article deals with the design of bimetallic bridges, their advantages in comparison with reinforced concrete bridges. Its given the characteristics and chemical composition of conventional bridged steel and high strength steels. The scheme of dividing continuous lash of span structure into spans is considered and the ratio of spans with equal bending moments is calculated. Its given the calculation of an effective three-span system. The existing efforts and bimetallic standard blocks of three types are proposed for them. Blocks are made of two types of steel: conventional cross section of bridge steel, heavily loaded cross section of structural high tensile. In block A, the lower belt; in block B the lower belt, the wall and thongs of the orthotropic plate; in block K the lower belt and the beam wall is made of strong steel. Such unification will significantly reduce labor intensity and weight of the structure.

Keywords: bimetallic, span structure,steel grade,enveloping the diagram, normal stresses, mounting block, sheet hire