International Bridge over Guadiana River Ayamonte (Huelva)

The bridge, 2 km away from the mouth of the Guadiana River, is part of the road link between Spain and Portugal, close to the Spanish town of Ayamonte (Huelva) and the Portuguese town of Castro Marim (the Algarve).

It was completed in 1991, after nearly four years, and has a total length of 666 m between the abutments, is 18 m wide and 20 m above sea level at its centre point.

The bridge is divided into five continuous spans, with a combined length of 594 m, long, are suspended by 64 pairs of cables. The two main towers, raised as an "A" and nearly 100 m high, have an opening at the foot of 30 m between the axes. The tower on the Spanish side is built on an artificial island in the river bed, and its equivalent tower on the Portuguese side, as well as two minor pillars, are built on-shore. The towers are hollow and the inside can be seen along their entire height; the cables are anchored in a single shaft at the top.

The bridge deck has four traffic lanes and parallel service sidewalks, where the cable anchors are located. The deck cross-section consists of a tray 2.5 m deep, stiffened inside along the anchored spans by triangulated diagonal sections.

The construction process began with the towers. Once they were raised and the starter segments were constructed, the deck was constructed using successive overhangs, with formwork carriages at each tower. Work was carried out on the four fronts at the same time (two per tower), supporting each successive overhang with the cables.

Significant technical innovations were applied to the works. The cables used a novel solution that resolved the problem of cracks and corrosion suffered by conventional cables, by removing the cement-grout injection. Furthermore, techniques were used for loading purposes, reducing the usual complications inherent to traditional systems, thanks to a comprehensive analysis of the mass-stress/length ratio. Finally, the entire assembly process was strictly supervised by the works team, using a complex computer program for this purpose.