Several urban design methodologies are suggested to reduce the amount of automobile traffic in cities. These proposals have significant environmental, health, and eonomic implications, with the latter not generally well understood.
Superblocks
Many cities, especially those whose development was planned, are arranged so that the city block is the basic unit defined by the streets. In a planned city, there is typically a network of north-south and east-west streets, which divide the non-road portion into rectangular areas. A city block is typically around 100 to 200 meters on a side, though it doesn’t necessarily have to be square.
See Tiran et al. (2023) for a basic overview of the superblock plan. A superblock, as envisioned for Barcelona, consists of a 3×3 array of regular city blocks and is about 400 meters on a side. Superblocks are created by closing two of every three streets in the north-south direction and in the east-west direction to through traffic, thus turning nine smaller city blocks into a single block. Using taxicab geometry and a typical walking speed of 5 kilometers per hour, it would take just under 10 minutes to walk from one corner of the superblock to the opposite corner. Thus a superblock defines a natural walkable community.
Medium population density, typical of rowhouses, townhouses, or low-rise apartments, is typically around 30-40 dwellings per hectare. If that is 60 people per hectare (1.5-2 people per dwelling), and we assume that half of the superblock is for residences, with the other half for other functions, then 480 people live in the superblock. High-rise apartments can support at least 25 times the density, allowing the superblock to house 12,000 or more people and thus support many day-to-day urban functions such as grocery stores, a variety of restaurants, and general practitioner doctor offices.
There is a significant gap between the vision for superblock design and what we have—so far at least—seen in practice. As Tiran et al. (2023) discuss, the original plan in the 1970s called for Barcelona to be divided into 503 superblocks. As of the publication of the report, six had been implemented, four of which have been implemented since 2016. As of 2019, their populations range from 5993 to 38,566 people in the San Antoni neighborhood, which is about three times the area of the prototypical superblock discussed above. As Magrinyà, Mercadé-Aloy, and Ruiz-Apilánez (2023) discuss, public opposition led to a reduction of the plan’s ambition to become the Green Axes plan, which calls for one of three streets in each direction to be closed to through traffic instead of two of three.
Health and Environmental Impacts
In the literature review Nieuwenhuijsen (2024), the authors discuss several rationales for the superblock program. The program has an explicit goal to reduce the amount of driving in Barcelona, and as such, these goals are similar to those of other driving reduction plans, such as mixed use development and road diets.
Chief among the reasons is environmental quality. Passenger vehicles constitute about 10% of world carbon dioxide emissions, and so reducing the amount of driving is viewed as a climate change solution. The space taken by roads, as well as the longer travel distances that abundant road infrastructure enable, are contributors to urban expansion and thus land use change. Cars are also major sources of air pollution, such as particulates, and noise pollution.
More walkable communities also have claimed health benefits. Nieuwenhuijsen (2024) discusses mental health benefits from the green space that will result from converting roads, and they discuss how improved walkability should improve physical fitness.
Palència et al. (2021) examine how several metrics evolved around three neighborhoods—-Poblenou, Sant Antoni, and Horta—-before and after the superblock transformations. In Horta, nitrous oxide emissions decreased by almost a third, while PM₁₀ emissions (particulate matter with particles up to a diameter of 10 microns) and PM₂.₅ decreased by about 25% and 8% respectively. However, there are issues with with pre and post measures occurring at the same points, and the post data was collected at the height of COVID-19 restrictions, and so when these factors are addressed, the authors do not find a significant effect of the intervention. In surveying residents about noise pollution, 45% of women and 50% of men thought that noise had decreased, while 8% thought it had increased.
San Antoni does not suffer from the two above problems. Palència et al. (2021) found that in San Antoni, NO₂ and PM₁₀ emissions declined by 25% and 17% respectively. Daytime noise decreased by 3.5 decibels, while there was no overall statistically significant change in nighttime noise. In Poblenou, there are not quantitative results available, but interviews with residents suggest that pollution levels decreased within the superblock and increased outside the superblock, as traffic was pushed to the surrounding streets. Overall, Palència et al. (2021) show some pollution benefits to the superblock treatment, but the results are not decisive or terribly impressive.
Rodriguez-Rey et al. (2022) apply a bespoke traffic and emissions model to determine the effect of various traffic policies. They find that on streets affected by superblock conversions, NO₂ pollution would go down by 17%, but those reductions would be offset on the streets that are not closed. They conclude that land use changes alone, such as street closures, would not be sufficient to reduce driving and air pollution, and that other policies are needed. Majoral, Sarwar, and Saurí (2025) model the effects of a superblock expansion on traffic and reach a similar conclusion: implementation should primarily shift traffic to main roads and have little effect on overall driving, and if a reduction in driving is the goal, additional policies are needed.
Mueller et al. (2020) are more optimistic about the prospect for reducing travel. They estimate that 19.2% of private automobile trips would be reduced from full implementation of Barcelona’s 503 superblocks. That number is based on modeling from the 2013-2018 Barcelona Mobility Plan and includes a range of policies to discourage driving and encourage active transportation beyond land use changes. They find a health impact of 667 reduced premature deaths per year, which are brought about from reduced NO₂ exposure (291 deaths), reduced noise (163), reduction in the urban heat island effect (117), extra green space (60), and increased physical activity (36).
Overall, the results are not decisive, but they do show some health and benefits to the superblock system. They also show that the benefits will be very modest unless paired with other measures to discourage driving.
Economics of Superblocks
Little research has considered the economic effects of superblocks specifically, and even on the broader question of the economic impact of driving restrictions, research is limited. Meijers, Hoogerbrugge, and Cardoso (2018), which is more extensively discussed in our analysis of polycentricity, considers several forms of integration in polycentric urban regions, which are collections of cities that are within a single commuting network but in which no one city is dominant. They find that more integrated regions, including integration by fast road travel, more strongly reap the benefits of agglomeration economy than less integrated regions.
Nederveen et al. (1999) consider the economic impact of parking restrictions. They find that parking restrictions bring economic benefit to the businesses in the immediately affected areas, but they harm businesses in adjacent neighborhoods. The authors do not consider the broader, citywide economic effect.
Huang, Li, and Ross (2018) consider the impact of changes in the price of Singapore’s Certificate of Entitlement, which the Singapore government issues as a right to own a car. They find that as the cost of the COE increases, the property value gradient in the city increases, meaning that there is a larger difference between property values in the central city and in the periphery. This result should be expected under the standard urban model, or the Alonso-Muth-Mills model, which holds that property values plus the cost of transportation to the central business district should be constant throughout the city.
The evidence is not decisive, but it suggests that limitations on driving, such as from superblock design, will have a negative impact on a city’s economy, especially in the periphery, due to the loss of the agglomeration effect that results from a high-capacity road network.
Expansion of Superblocks
Most superblock implementation worldwide has been in Barcelona, but there is interest in bringing the superblock concept to other cities, such as Vienna’s Supergrätzl. Li and Wilson (2023) find 5-50% of the residential area in Los Angeles would be amenable to superblock transformation, depending on how stringently they apply their criteria. They apply five criteria to identify suitable potential superblocks:
- Superblocks should not contain arterial streets defined by the General Plan Circulation System.
- Superblocks must be surrounded by arterial streets to facilitate circulation and minimize traffic congestion.
- Superblocks should not contain road segments in the Vehicle Enhanced Network.
- A greater total length of non-arterial road segments contained in the Neighborhood Enhanced Network, Bicycle Enhanced Network and Pedestrian Enhanced Districts is favored.
- Superblocks should cover at least 100,000 square feet.
Eggimann (2022) examines 18 cities worldwide and among them finds that 40% of the street network would be amenable to conversion to superblocks or miniblocks, defined as 2×2 arrays of city blocks rather than 3×3 arrays. He notes that a city having a regular, rectangular network of streets is neither necessary or sufficient to be amenable to superblock or miniblock conversion.
However, the expansion of superblocks faces significant challenges. Frago and Morcuende (2024) observe that the perceived right to drive is a powerful political force, and any policy that is perceived as restricting the freedom to drive is going to meet with severe opposition.
Oscilowicz et al. (2020) discuss gentrification in the context of pedestrianization of urban areas. Gentrification is the process of a neighborhood becoming more expensive as it improves, thereby causing the displacement of long-term residents who can no longer afford it. Oscilowicz et al. (2020) find that the use of public greenspace tends to be higher soon after a superblock conversion, and then it falls off as gentification causes the perception among families that the green space is for people who are “not like them”.
References
Tiran, J., Goluža, M., Grigsby, J., Iturralde Farrus, B., Lemmerer, H., Leth, U., Frey, H., Lorenz, F., Müller, J., Stein, T., Gebhardt, V., Vith, T. “Literature review on Superblocks’ effects on the urban realm”. (J. Tiran, Ed.; D2.1). 2023.
Magrinyà, F., Mercadé-Aloy, J., and Ruiz-Apilánez, B. “Merging Green and Active Transportation Infrastructure towards an Equitable Accessibility to Green Areas: Barcelona Green Axes”. Land 12(4): 919. April 2023.
Nieuwenhuijsen, M., De Nazelle, A., Pradas, M.C., Daher, C., Dzhambov, A.M., Echave, C., Gössling, S., Iungman, T., Khreis, H., Kirby, N., Khomenko, S., Leth, U., Lorenz, F., Matkovic, V., Müller, J., Palència, L., Barboza, E. P., Pérez, K., Tatah, L., Tiran, J., Mueller, N. “The Superblock model: A review of an innovative urban model for sustainability, liveability, health and well-being”. Environmental Research 251(1): 118550. June 2024.
Palència, L., León-Gómez, B. B., Olabarría, M., Pérez, C., Artazcoz, L.. José López, M., Gómez, A., Marí-dell’Olmo, M., Rico, M., Puig-Ribera, A., Arumí-Prat, I., Cirera, E., Serrabou, M. S., Codina, A., Márquez, S., Cirach, M., Carrasco, G. “Salut als Carrers (Health in the streets)”. Agència de Salut Pública de Barcelona. 2021.
Rodriguez-Rey, D., Guevara, M., Linares, M.P., Casanovas, J., Armengol, J.M., Benavides, J., Soret, A., Jorba, O., Tena, C., García-Pando, C.P. “To what extent the traffic restriction policies applied in Barcelona city can improve its air quality?”. Science of the Total Environment 807:150743. February 2022.
Majoral, G., Sarwar, S., Saurí, S. “Effects of Superblocks on Travel Demand: A Cost–Benefit and System Dynamics Analysis”. Journal of Urban Planning and Development 151(2): 04025005. June 2025.
Mueller, N., Rojas-Rueda, D., Khreis, H., Cirach, M., Andrés, D., Ballester, J., Bartoll, X., Daher, C., Deluca, A., Echave, C., Milà, C., Márquez, S., Palou, J., Pérez, K., Tonne, C., Stevenson, M., Rueda, S., Nieuwenhuijsen, M. “Changing the urban design of cities for health: The superblock model”. Environment International 134:105132. January 2020.
Li, K., Wilson, J.P. “Modeling the Health Benefits of Superblocks across the City of Los Angeles”. Applied Sciences 13(4): 2095. February 2023.
Eggimann, S. “The potential of implementing superblocks for multifunctional street use in cities”. Nature Sustainability 5, pp. 406-414. March 2022.
Frago, L., Morcuende, A. “Urban Planning Paradoxes and Sociospatial Fragmentation: The Superblock Barcelona Case (2016–2023)”. International Journal of Urban and Regional Research 48(6), pp. 1055-1078. November 2024.
Oscilowicz, E., Honey-Rosés, J., Anguelovski, I., Triguero-Mas, M., Cole, H. “Young families and children in gentrifying neighbourhoods: how gentrification reshapes use and perception of green play spaces”. Local Environment 25(10), pp. 765-786. October 2020.
Meijers, E., Hoogerbrugge, M., Cardoso, R. “Beyond Polycentricity: Does Stronger Integration Between Cities in Polycentric Urban Regions Improve Performance?”. Tijdschrift voor Economische en Sociale Geografie 109(1), pp. 1-12. February 2018.
Nederveen, A.A., Sarkar, S., Molenkamp, L., Van de Heijden, R.E. “Importance of Public Involvement: A Look at Car-free City Policy in The Netherlands”. Transportation Research Record 1685(1), pp. 128-134. 1999.
Huang, N., Li, J., Ross, A. “The impact of the cost of car ownership on the house price gradient in Singapore”. Regional Science and Urban Economics 68, pp. 160-171. January 2018.