De Oversteek
Belgian practice NeyPoulissen Architects & Engineers have recently won the international competition to design & build the new bridge “De Oversteek” in Nijmegen, the Netherlands. The practice, formed by structural engineering office Ney and Partners and architect Chris Poulissen has teamed up to produce the winning scheme.

The project includes a tied-arch bridge over the Waal river, as well as the approach viaducts. This new crossing will connect the western part of the city to the ring road and will allow redevelopment of the southern docklands.

The scenography of the new crossing has played an important role in the project. The design results from the imposing dimensions of the river Waal, including forelands and shores, and in turn shapes the surrounding urban environment.

The bridge will have a strong symbolic form for the city as a double “gate”: Under the arch for boats approaching the city from the river and through the arch legs for vehicles and pedestrians entering from the South.

The new crossing is not considered as a highway bridge but rather as a city bridge: The material used for the approach viaducts is brick masonry to respect the roman heritage of Nijmegen and the piers follow the traditional building techniques of in-situ concrete. The human scale plays an important role in the plan view, elevation, materials and details of the design, being the link between an optimized engineering process and the surrounding urban landscape and architecture.

High-end engineering and a strong formal language were the tools used in the form-finding process of the tied-arch structure, which spans the whole river width rather than the navigation part in order to acknowledge and accentuate the river itself. Based on three basic parameters, several forms were structurally tested with the objective to increase the verticality of the arch legs and to rationalize the arch cross-section in smooth shape transitions. Performance indicators included resulting stresses in the structure as well as fabrication constraints. The reduction of the number of parameters involved in the overall geometry is achieved by the simplification of the arch topology. Structural efficiency is visible: shaping forces being taken into account in the form-finding stage and the absence of additional artifacts on the bridge result in a clear engineering and architectural concept, consistent with natural physical laws and urban relationships.

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6 photos and 4 drawings