Within the framework of the Urban Master Plan for the Barcelona Metropolitan Area, this parallel study is conducted to assess the potential for the conversion of the metropolitan radial roads. These currently high-capacity and highly specialized roads, which segregate the surrounding neighborhoods, can be transformed into spaces for territorial, environmental, urban, and civic interaction, completing the private, public, and active mobility system to define the metropolitan avenues of the future.

The B-23 road is a paradigmatic case. It stretches for 5 kilometers from the Ronda de Dalt in Barcelona to the Llobregat River, with a continuous layout of gentle slopes and well-characterized sections that can be understood as part of Barcelona's Diagonal Avenue. Proper interpretation of the geography and history allows for the connection and utilization of the interstitial spaces to unfold new economic and residential activities and bring nature to the metropolis.

The project seizes the opportunity to present an innovative city that makes the cities in its surroundings more efficient and "smart." It establishes, through the landscape, continuity between nature and the metropolitan cities. It will be possible to reduce or erase the current fracture of the B-23, creating urban sectors that diminish its significance and constitute urban continuity. It is a "resilient" strategy for changing mobility, increasingly sustainable, and becoming a model for other cities.