This section of the high speed railway line Vitoria-Bilbao-San Sebastian has an overall length of 1.3 miles (2.1 km). The project´s section is located in the municipality of Elorrio that is an industrial town in a mountainous region, located 39 km away of Bilbao.
This two-track alignment is designed for an operation speed of 140 mph (220 km/h). The minimum radius is 8,202 ft (2,500 m) and has a maximum gradient of 2.5 %.
Detailed design of three HSR viaducts. Although the segment is relatively small,
due to its complex topography, it presents five structures with an overall length of 0.96 miles (1.54 km) and a tunnel. The width of the viaducts varies from 28 ft (8.5 m) to 59 ft (18 m) depending on the supported number of tracks, with spans ranging from 118 to 213 ft (36 to 65 m). All of viaducts consist of post-tensioned concrete box girders and are built with moveable scaffolding systems, span by span. The piers heights vary from 59 to 242 ft (18 to 74 m).
The bridges are segmental structures cast-in-place using a span by span erection method with a self-propelled form traveler supported on one pier and the edge of the previously erected span. As a result, the construction does not interfere with the traffic underneath and mitigates the environmental impact.