Moveable Sails for Bilbao

Estuary ports are a recurring feature of European coastlines. Where adventurous explorers set sail towards shores unknown (to them) hundreds of years ago, industrial port structures of unseen size were built during the 20th century. Now, nature and people are reclaiming their parts in these areas. We, as bridge designers, are increasingly asked to develop foot and bike links between suburbs, somewhat lost between ports and city center, all the while respecting the latest environmental regulations and ship traffic demands.There is sometimes confusion about the open and closed state of moveable bridges. In truth, they move from one open condition to another open condition: open for pedestrian and bike traffic, or open for ship traffic. During movement, they perform a spectacle: they are more alive than most bridges we design, which is also their peculiar challenge.This paper focuses on the conceptual design of one such bridge currently under construction, between Erandio and Barakaldo, north of Bilbao, two communities physically close, but historically divided by the estuary. Bikers and pedestrians can traverse the river estuary, divided by vertical sails and benches along its length. The two sail-supported segments allow the passage of larger ships and sailboats by elegantly rotating horizontally on slewing bearings concealed in the main piers. The back-spans of the sails are locked to the fixed approach spans at their ends to create a continuous girder in the closed condition.