The invention refers to an improvement in the construction of segmental spans such as bridges and similar structures by the method known as "step-by-step" consisting in mounting segments or modules in succession at the end of a cantilever span section already erected. In accordance with this improvement, each module is moved in the decking parallel with its width as far as a stand-by position, then lifted by an arm which is pivoted a quarter of a turn about a vertical post located beside the module and inboard of the span section and resting on it by two beams. The module is next lowered and is in the erection position.

A cable-stayed girder bridge having a concrete deck girder which includes longitudinally extending stiffening girders having cables embedded therein and a laterally extending deck portion is constructed by sequential formation of said deck girder in successive adjacent sections. The longitudinally extending stiffening girder portions of said deck girder are first formed, support cables are embedded therein and subsequently tensioned. After hardening of the stiffening girders, the laterally extending deck portion of the duck girder is formed. A form carrier movable along the bridge during its construction extends in a cantilevered arrangement from a previously formed deck girder section to provide support for a successive deck girder section during formation thereof.

A system for rapid, cost-effective construction of highway bridges, traffic verpasses and bypasses, and causeways over water or wetlands utilizes light-lift crane structures together with modular, light-lift bridge sections and an enhanced stabilized crane, using controlled cables, to improve the safety and efficiency of the construction process. Stabilization of the payload against pendulation and rotation enables safe operation in harsh environmental situations such as wind. The construction system utilizes continuous site assembly processes for building bridges and causeways from repetitive modular elements. In some embodiments, the system uses the payload (one or more modular bridge sections) as a component of a stable lifting and positioning system, thereby eliminating the need for heavy auxiliary lifting equipment such as spreader bars and platforms. Lifting cables of the crane are directly attached to the bridge payload, which becomes part of the lifting system during placement. Other embodiments utilize installed modular elements as a staging platform for constructing subsequent modular elements.