Background:
The Eixample (the famous grid by Idelfons Cerdà) is the district with the highest levels of air and noise pollution in the city of Barcelona, with the worst deficit of green areas, with only 2m2 of green space per inhabitant, and with streets where vehicles occupy 60% of the surface when they represent only 20% of users.
The city of Barcelona aims to reformulate this situation by establishing a new articulation of networks for active mobility (walking and cycling), road traffic, and public transport that can reverse the situation. Thus, the concept of green axes (streets of shared space with maximization of green spaces) is born as an evolution of the superblocks concept.
In 2020, the Barcelona City Council announced an international competition to undertake the design of four green axes and four squares at the intersections between the axes.
The team we present won the competition for Carrer Girona, where a project with an area of 16,466.00 m2 is developed, which represents a cost of €7,322,950.43 (Contract Execution Budget excl. VAT).
Concept:
The application of the green axes concept (Superblocks) to the Eixample implies a global reorganization of mobility that allows freeing approximately 1 out of every 3 streets from through traffic to convert them into shared space. In these streets, cars cannot circulate linearly and are required to turn at every intersection. This creates a new network of green axes and squares that acts as an environmental and social infrastructure, improving comfort and health conditions, increasing greenery, and systemic and balanced stay spaces throughout the area.
The new "green axes" allow the creation of new meaningful routes, connecting public spaces of reference and connecting the Eixample with the peripheral neighborhoods. The new "squares" appear at the intersections of the green axes, creating a new typology of broader, more naturalized public space for citizen use where previously there were only streets.
The projects follow the guidelines established in a Model Green Axes document, which is the result of a co-production process between multidisciplinary professional teams (i.e. the competition winners) and municipal technicians, as well as various participatory processes with the involved actors, including residents.
People are the main recipients of the new green axis model. A unique platform of universal accessibility is configured, where vehicles are invited agents and pedestrians always have priority.
Design:
The previous conditions offer a strong contrast between the rigidity of the block geometry and the built diversity, with a markedly heritage character in the urban landscape of Carrer Girona. The starting section of the 20m street dates back to 1863, with sidewalks of 5m and a central roadway of 10m, flanked by alignment trees (mostly platanus x hispanica and celtis australis).
The design strategy, starting from the maintenance of the existing trees, involves the construction of a system of solutions that maintains a high level of flexibility regarding its use as public space, responding to and exploiting its singularities. The new design treats the street as a three-dimensional environmental infrastructure that adapts to the impacts of climate change, improving health conditions, comfort, emotional well-being, and biodiversity. The subsoil is regenerated, with a richer and draining base (including the use of structural soil), SUDs are incorporated, the permeable surface is increased, and new vegetation and trees are planted.
The strategy of the new plantations involves introducing new trees outside the original strict alignment and promoting a green explosion at the corners, based on the introduction of non-paved areas with compact and diverse persistent sub-shrubs and perennials. The continuous canopy tunnel effect is sought, complemented by medium-sized trees and multi-trunk trees with a lower canopy to enrich pedestrian perception on various scales and distances.
Regarding pavements, the use of the characteristic "panot" of the city of Barcelona is maintained in contact with the buildings, and granite pieces are introduced in the central part of the street and the trapezoidal corners, reusing the ancient granite cobblestones found under the demolished asphalt. Other findings, such as tramway tracks revealed by demolition works in the position indicated by historical cartography, are integrated in the new layout. Additionally, to reinforce the concatenation of stay spaces generated, a variety of urban furniture is introduced, including a design of large wooden platforms -tatamis- for a more informal and playful use.
Overall, the design is conceived as an articulation of active mobility, green, cultural, and environmental infrastructures. It generates walking and stay spaces for pedestrians, increasing nearby green spaces in a district with a strong deficiency due to its built density. It values the city's heritage and recovers elements buried by the car-centric city with asphalt (e.g., granite cobblestones buried for more than 50 years or tramway tracks that used to run through the streets). The street is given the capacity to store rainwater in its subsoil in symbiosis with existing vegetation and new plantations, thereby enhancing biodiversity and the provision of ecosystem services to the future grid of green axes in the city of Barcelona.
