FCC Construccion
The Almonte Viaduct in western Spain is 3,268 ft long.
FCC Construccion
The contractor expects to complete the $130-million contract in the first quarter of 2016.

Upon completion this fall, the Almonte Viaduct in western Spain will hold the record for the longest high-speed-rail bridge arch span, according to the government. Despite this imminent high-profile success, however, Spanish civil construction spending remains at a fraction of what it was before the 2008 financial crisis.

The 3,268-ft-long Almonte Viaduct, located at the end of the Alcántara reservoir in the province of Cáceres in the west of Spain, is being developed by the state-owned Administrador de Infraestructuras Ferroviarias as part of a 3.9-mile subsection that includes four viaducts, two flyovers and one underpass. The $130-million contract was awarded to a consortium led by Spanish contractor FCC Construcción in 2010 for a 32-month construction period, which has been extended by 18 months already and has a projected completion in the first quarter of 2016, according to FCC.

The viaduct itself is due for completion in October.

The project is part of the high-speed Madrid-Extremadura railway line linking Madrid to the seaports of Portugal, one of several public-works projects that constituted a massive infrastructure overhaul initiated in Spain 25 years ago. Spain's economy was one of the hardest hit by the 2008 financial meltdown, however. The country halted many of its ambitious programs, and the Madrid-Extremadura line suffered several delays as well. Its scope has also been clipped.

“With the ‘crisis,’ the Portugal section has stopped, but we hope it will be reactivated,” says Alberto Enciso, FCC's director of transport. “If it isn’t reactivated, it will remain a [high-speed rail] connection between Madrid and Extremadura, cutting the journey time by up to 50%.”

“However, the most important thing is that the line connect to Lisbon so that it becomes an important commercial and logistical axis that will drive the Spanish and Portuguese, and indeed the European, economies, through having a direct port to America,” he says.

According to Pedro Cavero de Pablo, FCC’s project manager on AVE Alcantara-Garrovillas, the Almonte viaduct is the most challenging section of the entire line—“probably one of the biggest challenges that the project team will ever encounter in their professional lives.”

The environmental-impact clause of the project dictates that no support can be cemented to the riverbed, so the 1,260-ft-long concrete arch span will straddle the entire width of the Almonte river. Once finished, it will become the world’s longest railway arch span and the third largest concrete arch structure, after the 1,381-ft Wanxian bridge in China and the 1,280-ft KRK bridge in Croatia.

“The arc geometry varies in its edge and width with each centimeter that it advances,” Cavero de Pablo says. “In addition, it has two arms in its first [295 ft] and just one arm in the remaining [669 ft], making its construction an authentic daily challenge.” Up to 200 crew members and engineers have been working on the site daily, pouring over 1.8 million cu ft of concrete, placing more than 2,000 tonnes of S-355 and S-460 steel, more than 1,000 tonnes of cables and over 6,000 tonnes of corrugated iron.

The viaduct’s overall deck, which includes a hyperstatic caisson 46 ft wide and 10.2 ft thick, is made up of 23 spans that range in size from 118 to 148 ft. The deck is supported above the concrete arch with eight pylons; an additional 14 pylons, reaching up to 213 feet, support the access spans.

Unfortunately, the completion of the viaduct does not signal a return to a healthy construction market in Spain. “For me, this viaduct is a significant project in all its aspects, yet it does not imply that the Spanish economy is recovering,” Enciso says. Since the viaduct was commissioned in 2010, investment has fallen “drastically,” he explains, including in the transport area.

Like most Spanish contractors, FCC is finding its biggest new projects abroad rather than in Spain, Enciso said, including in the Middle East and Latin America.