T-11, the road between Tarragona and Reus airport, Catalonia, Spain, presented two lanes in each direction, but due to the various intersections with smaller roads and private properties, did not deliver the quality standard of a highway. Due to the relevance of the road and the traffic volume, a profound road improvement was developed, with elimination of several intersections, improvement of others and widening of some road sections. These works, and the fact that the existing pedestrian crossings became obsolete in terms of accessibility, required the construction of four new footbridges.
Due to different geometry requirements, the spans of the structures vary between 19.55 and 28.50 m. The carbon steel Vierendeel truss is connected with GFRP panels that act like webs of the girder. Each footbridge has a set of ramp and stairs on each side. Again, although the layout is similar on every bridge, the spans and dimensions vary according to specific requirements of each location.
The cross section of the deck consists of two steel box cross-sections (lower chords) and two upper chords (a plate with variable thickness), connected by vertical posts spaced at 2.20 m. Transversally, the lower chords are connected every 2.20 m by a floor GFRP beam. On top of the transverse beams, the GFRP panels, with anti-sliding finish, are used as the pedestrian deck. The deck is supported by the central steel pier and the ramps. In all supports, elastomeric bearings have been used. The lighting system is encased on the vertical posts and the hand rail is connected to the upper chord of the Vierendeel. Both the ramps and the stairs are reinforced concrete structures, with variable spans according to local constraints of each bridge.
During the construction of the ramps and pier foundations on site, the steelwork contractor assembled the hybrid steel-GFRP structure at the factory. All the bridges were assembled in two segments to allow for their transport to the site. On site, with the pier and ramps built and the bearings in place, the first bridge segment was installed. The same procedure was applied to all the bridges: the first segment had the length of one whole span and 20% of the second span. This way, the second segment was supported by the ramp on one side and the cantilevered deck on the other, with the aid of a temporary steel component.