A-23 MUDÉJAR HIGHWAY IN SABIÑÁNIGO (HUESCA)

Location: Sabiñánigo (Huesca)
Contracting entity: MINISTERIO DE TRANSPORTES, MOVILIDAD Y AGENDA URBANA
Base bidding budget: 75.767.157,93 €
Completion period: February 2020 - February 2024

FEATURES:
The project consists of the construction of the new section of the A-23 Mudéjar highway, which will replace the existing N-330. The aim of this contract is to free the N-330 highway from long-distance traffic and complete the route that comprises the A-23 highway jointly with the A-21 Pamplona-Jaca and A-22 Huesca-Lleida highways.
The route has a total length of 8.6 km and includes three junctions (Sabiñánigo East, connection with the N-260 towards Biescas and Sabiñánigo West) and 18 structures: five overpasses, six underpasses and seven viaducts. Among the types of these structures one can find pre-tensioned double-T beams, post-tensioned lightened gull-wing slabs and rectangular concrete portal frames.
In addition, it is worth mentioning the 936-meter-long viaduct that crosses the Gállego and Aurín rivers. Due to the environmental protection of the rivers, it is not allowed to support the curved formwork on the bed of both rivers, so the construction procedure of self-launching girders and wing carriages was chosen.
The self-launching girder has a span of 92 meters, distributed over 11 spans, making it the longest viaduct in Europe to be built with this construction method. In addition to the complexity of using this construction procedure, there are several conditioning factors such as the 5% longitudinal slope, curves and superelevations, and variable edge sections along its entire length.
Therefore, a specific concreting procedure has been developed for each section, divided into 3 phases:
1)U-shaped section, with concreting volumes of 750 m3,
2)Upper slab, with volumes of 450 m3,
3)Side wings, with volumes of 420 m3.

This concreting procedure requires 16 hours of continuous work with four 56-meter pumps and 34 operators, as well as the supply of concrete from two concrete plants at the same time.
This project is of special complexity, not only because of the 18 structures, with the self-bridge viaduct, but also because of the large earthworks involved. On the one hand, excavations up to 26 meters high reaching a total volume of 1,689,295 m3, of which 649,204 m3 are excavated in rock by blasting and mechanical means. On the other hand, embankments of up to 16 meters in height made up of 1,538,534 m3 of material from excavation.