When the city of Barcelona started rolling out new “superblocks” in 2016—nine-block grids that reclaim streets from cars and turn them into pedestrian-first zones—the idea was controversial. But, the concept proved to work: As traffic disappeared from neighborhood streets, so did air pollution and noise. Green spaces helped reduce the urban “heat island” effect. Kids suddenly had a place to play. Benches and planters turned former traffic lanes into parks. More people started walking and biking.
A new study in Nature Sustainability looks at how the design could work in other cities that are also rethinking their use of urban space. “I think the strength of superblocks is that it provides a vision to transform cities that is not centered around cars,” says Sven Eggimann, an urban infrastructure researcher at the Swiss research institute Empa who authored the study.
The basic concept of a superblock is simple: Inside a tic-tac-toe-shaped street grid, three blocks wide and three blocks long, traffic is limited to residents only. Anyone driving farther has to go around the perimeter. The streets inside the superblock become public squares for the neighborhood, with the few cars that remain traveling at six miles per hour and yielding to people on foot. In Barcelona, where some neighborhoods were built with a perfect grid, the design works particularly well.
Eggimann used an algorithm to analyze the potential for superblocks—or a smaller version of the design that he calls “mini-blocks”—in more than a dozen other cities, looking both at how traffic flowed and the population density of each neighborhood.
The study found that some other cities with a similar layout could also easily adopt a similar model. In Mexico City, for example, more than 40% of the city could transform into superblocks with little disruption to traffic. Better yet, the study also found that superblocks are also feasible in cities like Tokyo, which doesn’t have a regular grid, but is densely populated and has efficient public transit. In Atlanta, which has a regular grid but low density, only a tiny fraction of the city is well-suited for the superblock design, Eggimann found.
“Density is important, as the superblock model focuses on districts where many people live to allow active street life,” says Eggimann. Having enough people in one area also makes public transportation efficient, he says, and good public transportation is part of what makes the superblock possible. The design doesn’t work well in sprawling neighborhoods that only have single-family homes—even if those neighborhoods have a perfect street grid, as is the case in Atlanta and many other American cities.
But as cities become more dense—moving in the direction of the “15-minute city,” where offices and simple errands are a short walk or bike ride away from home—designs like the superblock become more feasible. It’s important “to spatially bring together where people work, live, and spend their time,” Eggimann says. Smaller changes, like reducing traffic on a block or two, can also begin to help catalyze larger transformations.
While cities are taking a variety of approaches to rethinking traffic on streets, Eggimann thinks that superblocks can be especially useful. “I think the superblock model is particularly interesting as it strives for combined tackling of multiple challenges neighborhoods and cities are faced with—mobility, noise, walkability, urban green space—and that it is a model which envisions city-scale wide and broad transformation, going beyond single street transformation,” Eggimann says.
In Barcelona, for example, the city wants to create a connected network of superblocks that would include more green corridors in the city center, with the goal of allowing residents in the area to access a small park within at least 650 feet. “I think it is a more radical model, as the street could potentially be used for alternative purposes, and thus much more becomes possible,” he says.