A track record in high-speed rail

The technical complexity of building tunnels and viaducts breaks down into myriad engineering tasks, drawing on all the experience ACCIONA possesses in this expertise. The Company has become a sought-after partner in making such ventures a success.

Construction of high-speed rail lines began in Spain in 1986 with the building of the Madrid-Seville link. Since then, and till now, the country has placed itself at the cutting edge for this kind of work worldwide.

In 26 years, ACCIONA has laid a total of 1,216km of line, including the building of 165km of tunnels and 48km of viaducts, and assembled 1.401km of single track. Abroad, the Company has built the high-speed entrances to Bologna, on the Milan-Naples line, in Italy, using single-shield tunnel boring machines (TBMs) to yield twin tunnels of over 6km long.

ACCIONA has patented its own launched deck bridge-building system

Trains operating on high-speed railway infrastructure travel at speeds of up to 350kmph, which requires special conditions for ground and elevated track, and a large number of tunnels and viaducts in uneven areas. In the sections it has built, ACCIONA Infrastructure has contributed its own personnel, machinery and ancillary equipment to make projects a success.

Launched decks

On the first high-speed link ACCIONA Infrastructure worked on, the Company built 15 sections using novel solutions in various works, including the first construction of railway viaducts to use launched decks in Spain, on the Villanueva de Cordoba-Adamuz section in Spain's southern region of Andalusia.

In this constant process of technological evolution, ACCIONA improved - and later patented - its own launched-deck bridge-building system, using this mechanism to construct, among others, the great viaducts of the Arcos de Jalón-Santa María de Huerta section in Aragon (northeastern Spain) and those over the region's Huerva River for the Zaragoza bypass on the Madrid-Zaragoza-Barcelona-French Border line. These were the longest launches in Spain, able to transport up to 30,000 metric tons in weight.

This solution has served as the base for building many other high-speed viaducts in Spain. We have, however, built viaducts employing other solutions, such as decks built with successive cantilevers, mixed decks, prefabricated decks and those using self-supporting higher and lower arch centering.

For tunnel construction on high-speed lines, ACCIONA Infrastructure has used both TBMs and traditional hollowing and explosive methods.

The Company used TBMs to build the Guadarrama tunnels on the Madrid-Valladolid link, the Leon-Asturias (central and northern Spain) line tunnels and those on the Vigo-Das Maceiras Atlantic Axis link (northwestern Spain), as well as the Bologna tunnels on the Milan-Naples link in Italy.

The Guadarrama (central Spain) tunnels are parallel ones, each 28.6km long and of 9.9m diameter, for which double-shield TBMs were used as part of a joint project. There are 114 communication galleries crossing between the tunnels and they required the installation of 52.7km of Rheda 2000 ballastless track.

The Pajares tunnels in Asturias (northern Spain) are also parallel, each 25km long and 10m in diameter, and were built, in another joint project, using simple-shield TBMs. Their construction included 63 transverse communication galleries, as well as another for emergency exit.

Record-breaking tunnels

Construction of the Guadarrama and Pajares (northern Spain) tunnels represents a huge milestone for engineering with respect to the technical problems that were overcome using ad hoc solutions conceived especially for the job. Indeed, the Guadarrama tunnel is the fifth longest in Europe and seventh in the world. Those at Pajares are the sixth longest in Europe and 10th worldwide.

Spain's Guadarrama and Pajares tunnels are a great milestone in engineering in general and for the Company itself.

Tunnels built using conventional means include the following:

• The tunnel crossing the Serra Llarga mountain range in Lleida province (northwest Spain) on the Madrid-Zaragoza-Barcelona-French Border line, built under strict environmental controls avoiding disturbing a pair of eagles during the breeding and raising of their offspring.
• Naharros tunnel in Cuenca province on the Madrid-Castile-La Mancha Region- Valencia Region-Murcia Region line, where several galleries were discovered belonging to mines dating back to the height of the Roman Empire (1stC. AD).
• Madrid's 4.6km Paracuellos tunnel, the longest on the Madrid-Zaragoza-Barcelona-French Border line.
• The Villalgordo del Cabriel (eastern Spain) tunnel, which, alongside the one at Naharros (central Spain), is one of the longest built by conventional means on the Madrid-Castile-La Mancha Region- Valencia Region-Murcia Region line.