The Council of Extremadura decided in 1988 to commission the Lusitania Bridge to accommodate a sharp increase in regional traffic, which followed the promotion of Merida to the capital of Extremadura. The bridge connects the old town of Merida in western, central Spain to the newly developed area of Poligono on the northern side of the River Guadiana. The structure takes motor traffic away from the old Roman bridge, which has since been declared a footbridge.
The central load-bearing element of the bridge is its box girder: a torque tube 4.45 meters (14.5 feet) deep constructed from post-tensioned, pre-cast concrete elements.This element supports the loads of the dual carriageway along each of its sides. The loads of the bridge's approaches are delivered to reinforced concrete piers, which are spaced 45 meters (147.5 feet) apart. Within the center span, this box girder is suspended from the steel tied arch by 23 steel rod pairs. Pre-stressed concrete wings, supporting the road decks, cantilever from the concrete box girder and are post-tensioned to it. The upper surface of the box girder serves as a 5.5 meters (18 feet) wide roadway for pedestrians and cyclists.
Raised centrally above the dual carriageways, it passes through the concrete supports designed as portals for the bridge's arch. This elevated passageway permits unobstructed panoramic views of the area. Taking advantage of southern Spain's long dry summer season, the central box girder and the spine of the approaches were supported by scaffolding, and the central span was cast while supported on temporary piers resting on provisional gravel fill. Post-tensioning of the box caused it to rise slightly, so that the support structure could then be removed.
The Lusitania's generous dimensions are dictated by the width of the Rio Guadiana, and both the 139 meters (456 feet) side spans are dominated by a 34 meters (111.5 feet) deep central steel arch spanning 189 meters (620 feet). Being conceived as an integral structure, the bridge does not make use of expansion joints. The ancient rhythmic structure of the 2000-year-old Roman bridge, La Akazaba, 600 meters (1,970 feet) upstream is reflected in the spacing of the load-bearing piers for the approaches.
1988 - 1991
Puente de Lusitania