The Bilbao metro, after crossing the river over the two arch bridges of Bolueta, included in the arch bridges, crosses the river again at a place very close to the second one. At this point, the metro crosses the river on two superimposed levels, because the Etxebarri depot is located on the left bank of the river, and this makes it necessary to create a crossing at a different level, which has made it necessary to build a bridge with two platforms over the river, which is extended on both banks with access viaducts.

The bridge crosses the river at an oblique angle and it is not possible to place piers over the river, so a single-span bridge with a span of 86 metres has been built. The two levels led to the bridge being built with a prestressed concrete triangulated girder, with a Warren triangulation to make the structure as clear as possible.

The obliquity and the load of the two levels with a double metro track have led to the bridge being built with three segments, two lateral and one central, joined by the upper and lower slabs.

The bridge is built with precast segments in a Z-shape, formed by the upper slab, the lower slab and a diagonal. The segments are assembled by successive cantilevering by crane. To do this, two provisional supports are placed on the river’s edge approximately 10 metres from the definitive supports.

In this way, the bridge has a first provisional span from which the cantilever starts until it closes at the keystone. Once the keystone is closed, the provisional supports are removed and the triangulated beam remains supported at the ends.