Leon Blum Viaduct

The new crossing spans over a large high speed rail station and the Boivre river valley running through the center of Poitiers. It replaces a concrete footbridge, now demolished, and expands the functionality of the crossing. It does so by providing access to the city center via a BRT bus network (Bus Rapid Transit), and a BRT station on its deck as part of bridge design. The new bridge therefore plays strategic role for the city development at a large scale.

The design consists of a 310 meter long composite truss. It is divided into 5 spans, with a main span of 81 meters. Of critical importance for the design was the integration of the project into the city surroundings and the railway platforms. The height of the structure over the station platforms increased the aesthetic requirements for the soffit. The truss system superstructure is continuous with the bridge piers that are articulated at their base. With this design, one perceives a cohesive tubular structure emerging from the footings.

Construction over active high speed rail required careful coordination with the rail operators and limited erection time during several nightly closures. Steel segments and pre-casting of the concrete deck and underside panels reduced site activities and lifts over the railway. In addition, the design build procurement allowed the design and construction to be fully integrated and streamlined the design, fabrication, and construction schedule.

The extensive studies carried out during detail design stage allowed to design a viaduct in full conformity and coherence with the initial conceptual vision. During this design process, the sections of the structural components have been optimized and refined to emphasize the slenderness of the architectural composition.