Span-by-span erection with self-launching gantries is the most common construction method for precast segmental bridges. From the very first applications with huge self-launching trusses made of low-grade steels and hundreds of labor-intensive field splices, the single-girder overhead gantries have evolved into light and compact machines that are easier to operate and provide unrivalled versatility in highway bridges in median and light-rail transit projects with tight plan and vertical curves.

In 21 pages, the eManual explores the evolution of the first-generation single-truss overhead gantries into modern non-articulated machines comprising front integral L-legs and rear C-frame, and the state-of-the-art telescopic gantries featuring main girder and underbridge connected by a central turntable.

For both families of self-launching gantries, the eManual provides exhaustive coverage of the loads, self-launch kinematics, performance and productivity, and when these machines should be selected in lieu of twin-girder overhead gantries. The eManual also discusses deck construction, the stiffness interactions to consider for the design of piers and superstructures, and staged application of post-tensioning to avoid decompression of epoxy joints and the risk of brittle span failure.

• Introduction
• Loading, kinematics, typical features
• Support, launch and lock systems
• Performance and productivity
• Structure-equipment interaction
• References

The eManual provides exhaustive coverage of the topic for bridge owners, designers and construction professionals interested in span-by-span construction of precast segmental bridges. Other monographs of the eManuals Project discuss segment fabrication, the span assembly operations common to all families of self-launching gantries, and the other types of self-launching gantries used for span-by-span construction.

The collection Span-by-Span Construction of Precast Segmental Bridges (134 pages) provides exhaustive coverage of span-by-span construction, ranging from segment fabrication by short- and long-line casting to the different types of self-launching gantries used for span erection, and is offered with 10% discount on the cover price of the five eManuals.