Alfa Polaris designs new footbridge to merge two previously divided neighbourhoods
The construction of the Can Gilli Footbridge was an old claim of the inhabitants of two neighbourhoods separated from one another by the trench of the BV-1432 road. So far, people from one neighbourhood wanting to go to the other one had to make a detour, crossing the road through a highway bridge, placed at the east border of these urban areas, with a single narrow footway in one of the sides of its deck.
The client and the designers looked for a solution with reduced whole life cost and environmental burdens. As a result the team, led by structural engineer Xavier Font, chose Corten steel (whose rusted skin protects itself from further corrosion) for the structure; LED lamps (with long life span and energy efficiency) for the street lighting over the deck; and polymeric timber (with almost no maintenance) for the decking over the structure.
A cranked shape beam varying in width and in depth was proposed, formed by two Corten steel longitudinal hollow box girders. Over the main span the footpath is channelled by these two box girders which are linked together at bottom flanges by transversal beams. The latter, in turn, gives support to the 2m wide polymeric timber decking through longitudinal joists. Over the south foundation, placed on a small platform that is in the middle of the south cutting of the trench, the main cranked beam takes a V shape, the top ends of which give support to a small deck.
The design of the new footbridge was strongly conditioned by the asymmetric shape of the cross section of the road trench. Alfa Polaris looked for a design that highlighted this asymmetry marked by the different level of the two banks and the presence of the mentioned small platform.
Client: Granollers Borough Council
Architectural design and structural engineering firm: Alfa Polaris S.L.
Street lighting engineering: GESA Gestió d’enginyeria, serveis i arquitectura
Main contractor: ACSA, Obras e Infraestructuras, S.A
Steel contractor: Talleres Plain, S.A.