Millimetric Precision for Building the 906-meter Los Feos Viaduct

Sacyr Engineering and Infrastructure is building the railway section Los Arejos-Níjar, which is part of the Mediterranean Corridor of the High-Speed Line Murcia-Almería (Spain).

Among the unique infrastructures of the section, three viaducts stand out, which will be launched from one of their supports. The first of them is the Los Feos Viaduct.

This viaduct over the dry bed of a rambla is 906 meters long and its 17 spans total a collective maximum span of 67 meters. Its construction has just achieved a significant milestone: the first six culverts have been placed, at 153 meters in.

Launching in this type of viaduct, being so long and with such a self-weight to mobilize, is not a common occurrence, explains Francisco Julián Rodríguez Muñoz, manager for this project.

"Viaducts of mixed metal and concrete structure with a double-width track, by their very nature, are complicated. This one is even more so because we launch it with the lower concrete slabs and the upper pre-slabs installed. It will be secure among the national records of launches of metal railway bridges," Rodríguez adds.

35 Sacyr team members from diverse areas have successfully completed the launch of this first section, composed of six of the 34 culverts (each measuring 30 meters and weighing 100 tons) required for the infrastructure.



For the launching system, a lifting crane has been installed at the end of the bridge, while at the back of each section, the crawling tail is placed. There, 800-ton jacks are installed, which will be responsible for tensioning the drag cables and pushing the bridge forward. Rockers and side guides have been placed on all the piers and in the push park, which are responsible for sliding and fitting the bridge into place.

Once the entire deck has been launched, the upper and lower slabs will be assembled and concreted.

"In the first span span launch, you confirm that all the work of over a year has been done well," explains Francisco.

The secret to success lies in manufacturing tolerances and exhaustive topographic control, i.e., the minimum allowed errors in this process. When launching the spans from one support to the other, which is nearly a kilometer in length, geometric eccentricities must be minimal.

There is only a lateral margin of two centimeters along the entire length of the viaduct and three millimeters of flatness in the lower platform.




In total, six launches will be carried out: four of six spans and two of five. The last launch is scheduled to take place in the summer of 2024.

For the launch of the metal decks, high-precision topographic devices and sensors have been installed in various sections of the bridge and the nose. In addition, software has been developed to make geometric corrections in the launch process.

Through a tablet, mobile, or PC, one can check how the launch is progressing; any user can see the real-time data of the bridge's topography.

In the future, the viaduct will have seismic elements and state-of-the-art supports such as spherical supports and dampers, which will allow accommodating this viaduct of such length to different thermal and seismic effects.

Pondio Engineers have carried out the design and constructive project of the viaduct, the project for its launch, and provide technical support to Sacyr Engineering and Infrastructure.

  • Railway infrastructures
  • AVE
  • Viaducts
  • Spain

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