The mobility restructuration within Barcelona metropolitan area due to the 1992 Olympic Games empowered the splitting of C-32 motorway from Mongat to Barcelona, in order to link it with La Trinitat road junction and, from this point, to the ring roads. This new stretch, called B-20, ran through the municipalities of Mongat, Tiana, Badalona and Santa Coloma de Gramanet, and reached Barcelona. The special topography of the Maresme region and certain environmental awareness judiciously suggested the underground routing of the motorway. However, its urgent construction required that the works were made open cast, instead of executing them with a tunnel boring machine, so a box was created, that consequently had to be filled with soil. On the other hand, the scarce funds which the works were confronted with reduced the depth of the required burying process, so the box outcropped to the surface in some stretches and, on top of that, the workload that it had to support was lowered, so they had to diminish the volume of the land that could be located on top of it with the objective of reforesting the area.

The project that we carried out aimed to solve the impact of the road infrastructure, to restore the continuity of the territory and to build a park, not only on the 850 m long tunnel, but also in the entire area that had been expropriated for its construction (approximately 60,000 m2). Far from masking the motorway trace, our job was to dignify its mark within the territory, by proposing a promenade along the structure that could complement the reforesting process of the environment. This promenade is organised in two levels: a paved one, conceived as an itinerary for pedestrians and cyclists, and another one with grass, as a huge longitudinal meadow considered as a playground and a picnic area. The pedestrian itinerary is materialised by a 5.60m wide asphalt strip, painted in a blue and yellow checkerboard pattern, and a 4m wide printed concrete strip, that splits in order to overcome the elevation difference between both strips: in a horizontal one and in a variable bank to avoid punctual load transfer over the box. The meadow is made up of a 21.60 m long stretch, which undulates adapting itself to the original topography. Some groups of flowering trees are located