Superblock

What is a superblock?

A superblock is a group of neighbouring city blocks where through-traffic is moved to the outer edge and the streets inside the group are turned into shared, greened space for residents. In Catalan it is called a superilla, and the plural is superilles. The concept is most closely associated with Barcelona, where it became a flagship model for traffic calming and public space. Inside the superblock people walk, cycle, play and sit, while motor traffic is kept to the roads that surround the group, with local access still allowed at low speed.

How does the Barcelona superilla model work?

The model was promoted by the Barcelona Urban Ecology Agency and its director, the urban ecologist Salvador Rueda, and the city began applying it with pilot projects in the mid-2010s. The logic is straightforward. A grid of short city blocks normally carries traffic along every street, so the superblock groups several blocks, closes the internal streets to through-traffic and sends that traffic along the outer edges. The freed space is then redesigned for people. A typical superblock combines several measures:

• Through-traffic is routed onto the perimeter roads, which carry the main vehicle flow.
• Inner streets have low speed limits and give priority to people walking and cycling.
• Parking on the inner streets is reduced and relocated to the edge, or placed underground where that is practical.
• Former carriageways are planted with trees, seating and play areas, which adds shade and helps surface water soak into the ground.

The model depends on the perimeter roads being able to take the displaced traffic. That is why a superblock is a network decision and not only a decision about one street, and why it is usually introduced together with changes to bus routes and cycle paths.

Why does the older meaning of superblock still cause confusion?

In twentieth-century planning a superblock meant something different: a large residential or mixed development built as one unit, often set apart from the surrounding street grid. Modernist planners from the 1920s to the 1960s used large repeated building units and internal open ground for this purpose. The Radburn layout in New Jersey is a well-known precedent, because it separated pedestrian routes from vehicle routes as a central principle.

Slovak panel housing estates (sídliská) follow a similar logic of large, self-contained complexes, although local planning practice rarely used the word superblock for them. Anyone searching the term may therefore be looking for either meaning, and the two should be kept apart in a brief or a planning document.

What changes on the inner streets of a superblock?

The inner streets are the core of the model. The carriageway is narrowed or reshaped so that it no longer reads as a route for through traffic, and the surface may be laid at a single level so that pedestrians, cyclists and slow-moving residents share it. Trees, planters, benches and play equipment take the place of parked cars. Noise falls, and the streets become places where neighbours meet.

The design approach has similarities with shared space, where the removal of kerbs and signs encourages drivers to slow down through social negotiation. A superblock differs in one key respect: it does not rely on removing all traffic rules. It restricts through motor traffic by network design and keeps conventional traffic control on the perimeter, where speed and volume are highest.

The greening also has a climate purpose. Planting and shade reduce the heat that builds up on dark, sealed surfaces, which connects the superblock to the urban heat island problem. The effect is strongest where the inner streets are fully planted, not just decorated with a few trees.

How is a superblock different from a car-free zone?

Both ideas reduce the dominance of cars, but they work at different levels. A car-free zone usually restricts cars across a whole district through parking policy, access rules and ownership incentives. A superblock is a street-layout rule applied to a group of blocks: local access stays open at low speed, and the change is aimed at through traffic.

Does the superblock idea fit Slovak towns and new developments?

The idea is relevant to Slovak towns, because many residential areas were laid out for local access but now carry cut-through traffic. Older streets near town centres, and some housing estates, could benefit from rerouting through traffic onto a clear perimeter road, provided the surrounding network can absorb the displaced vehicles. Traffic capacity and emergency access must be checked before any change is made.

In new developments the principle is easier to apply, because the masterplan can set the perimeter road, the inner access streets and the planting from the start. In Slovakia the planning side sits with the territorial plan under the zákon o územnom plánovaní 200/2022, while construction is governed by the new building act 25/2025 Z. z., which applies since 1 April 2025. A superblock is not a term defined in either act, so it has to be expressed through the zoning, road design and municipal planning documents that the municipality adopts.

For a small Slovak town, the practical question is less about the model itself and more about the existing road hierarchy and the bus network. A superblock works where the perimeter can take the traffic, and it is usually best introduced with the local authority, residents and the transport operator at the same table.

What are the common misconceptions about superblocks?

• A superblock is not a gated estate. Pedestrians and residents can still pass through, and the streets remain public.
• Cars are not banned from the whole city. Through traffic is moved, not eliminated, and local access stays open.
• Greening is not decoration. Planting carries the drainage and cooling functions that the model depends on.
• The model does not succeed automatically. Its outcome depends on enforcement, the perimeter network and sustained maintenance of the planting.