Almonte HSR ViaductCáceres, Spain
This viaduct over the Alcántara Reservoir, which is part of the Madrid-Portuguese Border High Speed Rail (HSR) link, is a challenge for bridge design, engineering and construction. Its 384-m main span will make it the largest HSR arch in the world and the largest railway bridge in Spain. A both formally and structurally innovative design has been used to give response to the specific problems of a major HSR crossing from the design stage: the arch, linked to the deck at the crown, has an octagonal section with variable depth and width in its central 210 m, from where it splits itself into two legs with irregular hexagonal section until its springings. The design brings together structural efficiency, out-of-plane stability (as HSR horizontal deflection limits require), improved wind-load response, transparency, aesthetics and durability.