The San Sebastián City Council awarded Juan José Arenas the drafting of the project for a bridge to connect the center of San Sebastián with the Aiete neighbourhood.
This structure had to cross a valley located in the very urban center of the city, between the hills that border the coastline, saving a longitudinal slope of 9%. Taking all these circumstances into account, the chosen typology was the laminar arch bridge.
Our proposal was a slender arch, 90 m span, giving support to a deck of hollow cross section. The arch behaves like a shell vault, practically under uniform compression for every possible load case. Its shape derives from the condition of pure anti-funicular situation under the self-weight, leading us to design a polygonal vault.
Looking for a much greater visual slenderness, the vault is ripped on its axis with a void, forming two symmetrical vaults and also symmetrical pairs of thin wall piers. The whole bridge creates an incomparable architectonical object which underline the profile of the valley without filling its space.
Framing the urban valley, the polygonal flexible vaults produce a rest area of highest visual interest. The duality created by the vaults and the piers promotes in this way a stronger sense of structural integrity.
The night illumination underlines the different volumes of the bridge, in which we found visual contrasts and geometric integration.