How to use the Barcelona superblock concept for community and sustainability
Recent articles have featured Barcelona’s initiative to transform its car-dominated grid into a people-centric network. One illustrated the nature of the transformation and a second heralded the start of its implementation. These events mark a major city planning milestone, which has implications beyond Barcelona: They signal the beginning of a systematic approach to remodeling metropolitan areas everywhere with the intent to redress the imbalance among mobility modes. Moreover, they validate approaches for shaping new districts to achieve a movement system, which is inherently well-balanced. This article describes such a system: it incorporates and extends the principles underpinning Barcelona’s transformation to the design of street networks on undeveloped land.
The need to transform existing metros, and especially their overcrowded centers, became pressing in the 1960s; an inevitable outcome following 50 years of motorization in cities that were built at a time when auto-mobility was simply inconceivable. Sporadic responses that followed included cities closing streets to cars; declaring specific districts exclusive for pedestrians; redistributing traffic flows and removing highways from central areas or redirecting through-traffic to underground tunnels. All these case-by-case changes nurtured an appreciation for the vast improvement in the quality of the daily city experience, the heightened sociability and the intensified economic activity. In turn, this new appreciation generated greater demand for spaces and places endowed with these qualities.
What was still needed was a system, a model, which could be applied methodically to an entire city fabric that would change its texture and colour. A system that would also be equally applicable to existing districts and to undeveloped land. And while theoretical underpinnings for such a system were being developed, no comprehensive practical application had emerged — until now. Barcelona’s superilles (Catalan for superblock) and Calgary’s “fused grid” models stand at the forefront of implementation.
The main goals of both models are well-established, carefully researched and self-evident:
- To reclaim urban surface space from the over consuming motorized transport
- To reallocate such space so as to meet the needs of all modes of mobility equitably
- To introduce nearby nature in urban settings
- To reduce risk and annoyance in public spaces
- To foster sociability and enhance community cohesion
- To evoke delight in experiencing the city
To achieve these goals consistently, a neighbourhood layout follows a set of fundamental principles, which, in turn, generate repeatable patterns; just as Ildefons Cerdà’s original Eixample plan for Barcelona emerged from his social reform ideas.
Three overriding principles set the context for the creation of repeatable patterns:
- Circulation system hierarchy — adapting methods found in biological and man-made systems
- Filtered permeability — introducing physical and operational controls (switches) in network design
- A triad of vital spaces — seeing habitation, circulation and commons as inseparable parts
Hierarchy is an emergent characteristic of all complex systems, cities included. It allows for optimizing resources and performance in a well-functioning system. A street network, for example, need only occupy surface area proportional to the type, volume and speed of traffic moving on each of its parts; sizing each component in the hierarchy suitably, conserves resources and improves system performance. Research has revealed useful ratios of sizes found in natural systems that could guide the design of movement systems.
To reap the full benefits of hierarchy, however, filtered permeability becomes essential. Filters or “switches” are another universal characteristic of complex systems. For example: Open/closed stomata control breathing in plants; switches make telephony possible; on/off coded lights control traffic flow and floor-workers have no direct line to a company’s CEO. Switches (or filters), combined with a hierarchical structure, maximise total system outcomes.
Hierarchy and filtered permeability can manage mobility efficiently but might by-pass a crucial element of community — people interaction — which has a distinct physical counterpart: common ground (i.e. public space). It completes the triad of vital spaces of a functional, vibrant neighbourhood: habitation, circulation and commons.
These primary principles can be seen at work in the two applications of hybrid network models and their repeatable modules.
- No through motor traffic means that streets at the walking scale (400 x 400 m) serve as capillaries only; they occupy the lowest rank in the network hierarchy, where circulation essentially stops. They serve the residents of a “quadrant” (or “quartier”) only. They are unmistakably local and, thanks to lighter traffic, can be made narrower, freeing up space for other functions.
- Full accessibility for active transport within the quadrant: people circulation is switched “on” while motorized transport is “off” by means of looping cars back to its perimeter. This preferential filtering (i.e. diode) manages the permeability of the quadrant to its residents advantage. Additional switches, such as card-activated bollards and the scheduling for entry, parking and deliveries, would add accuracy and flexibility of the “on-off” switching and refine the filtering.
- Surface space gained from the circulatory function is then assigned to nature and to recreational/social activities thereby strengthening cohesion within each quadrant superille.
- The triad of vital spaces is clearly present in the diagrams.
These typical layouts, though publicly known under separate names, are, in essence, hybrid networks. They incorporate distinct elements into a functioning whole: public parks and open spaces that serve as social magnets double up as extensions of paths for pedestrians. Similarly, car routes within the quadrant can occasionally act as social spaces due to the induced low-speed, low-volume traffic. Through these transformations each element can play many roles, maximizing the efficiency of the system as a whole.
What emerges when you add to these design efficiencies the absorptive capacity of the open spaces; the enhanced security through informal surveillance; and the health outcomes of nearby nature and active transport, is an evolved grid — a hybrid model that addresses the key priorities of future cities.
Fanis Grammenos heads Urban Pattern Associates (UPA), a planning consultancy. UPA researches and promotes sustainable planning practices including the implementation of the Fused Grid, a new urban network model. He is a regular columnist for the Canadian Home Builder magazine, and author of Remaking the City Street Grid: A model for urban and suburban development. Reach him at fanis.grammenos at gmail.com
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