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What makes a public space great?

Our open-source app, CommonSpace, gives park operators and communities a new tool to study that vital question.

By Ananta Pandey and Sebastian Soto

A woman in a hijab looks at her phone

A surveyor using CommonSpace in R.V. Burgess Park. (David Pike / Sidewalk Labs)

Update: As of September 2020, CommonSpace is no longer live. However, all of the code is on Github and is freely licensed. We hope that anyone interested in bettering cities’ public spaces will further adapt and advance this open-source community project.

A vibrant public realm is the foundation of a strong urban community. Public spaces offer people a place to gather with friends, to run into neighbors, to be active, or to sit and reflect in nature. But what makes a public space great? It’s a question that, for much of history, planners and architects answered from a purely aesthetic perspective. That is, until a few key figures changed the way the profession — and indeed urbanists around the world — think about public spaces.

It started, as did many of the world’s greatest public spaces, in Italy. In the early 1960s, Jan Gehl was a young architect focused on the design of buildings — not the spaces between them. When he met Ingrid Mundt (later to become Ingrid Gehl), one of the first psychologists in Denmark studying human behavior in urban environments, she fundamentally shifted his thinking away from “bricks” and towards “people.” When Gehl received a travel scholarship to go to Siena in 1965, he and Ingrid used it to discover the ways people behave in public spaces.

Observing for hours on end, they noted where people sat in the square, where people stood, how many people were in the square in the morning, how many at night, how many in winter; how many in summer, and so on (How to Study Public Life). These early studies greatly influenced Gehl’s thinking and, indeed, the rest of his career. In fact, his careful documentation of people standing, sitting, waiting, and talking along Strøget, Copenhagen’s main thoroughfare, made the case for pedestrianizing the street, helping to transform the city into a global leader in vibrant, human-centered public spaces.

But while Gehl’s methodology has been embraced in the subsequent decades, inspiring planners to design public spaces for people, the tools used to study public space have changed very little. Today, urban planning researchers, managers of public spaces, and community advocates still rely on clipboards or manual clickers to count the number of people in a space and classify what they are doing — a slow and labor-intensive process that has hindered the widespread adoption of public life studies. While sensor-based counting methods, using cameras or infrared sensors, provide one potential alternative, they come with their own challenges, including cost, power and network requirements, privacy implications, and data quality.

Without public life studies, managers are left to steer the design, programming, and maintenance of spaces without full knowledge of what is happening on the ground or what communities need or want. Moreover, a lack of standardized, quantitative information can make it hard to share findings or compare interventions across cities.

To address these challenges, Sidewalk Labs has prototyped a digital application called CommonSpace that makes it easier for public space managers and community members to collect reliable, privacy-sensitive data on how people use public spaces. To prototype CommonSpace, Sidewalk Labs partnered with the non-profit Gehl Institute and a Canadian national charity, Park People. The app was field tested as part of Park People’s Public Space Incubator Program, an initiative that awards grants to experimental programming pilots in Toronto’s public spaces.

With CommonSpace, park operators or community organizers can enter information they observe about public life — such as what areas people tend to eat in, play in, or avoid—into a user-friendly app. The app records data in accordance with the Public Life Data Protocol, an open data standard (published by the Gehl Institute and founding municipal and private partners) that makes it possible to compare data from public spaces. The data collected with CommonSpace can be easily exported into visualization and analysis tools that communities and space managers alike can use to see patterns, generate insights, and develop evidence-based approaches to advocating for change.

We’ve also embedded Privacy by Design principles throughout CommonSpace; no personal information is recorded about the people who are observed in studies.

Managing a Public Life Study With and Without CommonSpace

In fall 2018, Sidewalk Labs worked with Park People and the Toronto-based Thorncliffe Park Women’s Committee to conduct a field test of CommonSpace in R.V. Burgess Park. The Thorncliffe Park Women’s Committee was funded by Park People’s Public Space Incubator to further develop the community cafe and market the committee had started in the park. The test concentrated on using CommonSpace to measure how increased programming and better cafe seating changed how people used the space. Local youth and other residents collected data on how many people came to the park and how the new chairs and programming affected what they did there.

The team found that the park saw a massive, 365 percent spike in visitors on programming days, and that the activity was far more social, with large increases in people coming in groups, meeting new people, and staying into the evening. For the Thorncliffe Park Women’s Committee, the study not only gathered valuable data that can help them understand and communicate the impact of their efforts, but it also enabled participants to learn about their community while changing how they think about the park.

Prototyping CommonSpace with our partners taught us some important lessons. First, we learned that user-centric technology could improve public studies by simplifying data collection and reducing friction for surveyors in a privacy-preserving way. Second, while we explored many different ideas (including more “high-tech” or automated solutions, such as cameras and computer vision), we learned that in-person approaches can be preferable because they lead to stronger studies: when community members participate, they not only add important local context but subsequently tend to become more active participants in the planning process (an outcome important to the long-term success of any public space).

Finally, we learned about the incredible variety of how people use their public spaces, and how hard it is to capture that activity in a standardized format. While the Public Life Data Protocol is a huge step forward, and will enable more global conversations about the design and programming of public spaces, the raw data itself is not enough to make important planning decisions, which requires a deeper understanding of the people who bring these spaces to life.

With these lessons in mind, we are excited to announce that, starting today, CommonSpace is publicly available for free on U.S. and Canadian app stores (Apple/Android) as a “beta test,” with open source code available on Github, for people in cities and organizations around the world to use to conduct their public life studies. While in “beta,” study administrators who are interested in conducting public life studies will need to start by reaching out to us to set up a CommonSpace administrator account.

If you’re a city or organization planning (or interested in planning) a public life study, please e-mail us at

If you’re just interested in seeing what CommonSpace can do, feel free to check out the demo version (the app does not require an account nor store any data; you can find the Responsible Data Use Assessment for CommonSpace here.)

The first goal of the beta test is to generate feedback. We’ll be asking CommonSpace users to leave their comments publicly on our Github page, so anyone can join the conversation.

The second goal of the beta test is to open CommonSpace to third-party development, so that new developers can adapt CommonSpace to work better for their communities. We believe open-source tools are better for cities, because prevent lock-in around single vendors, they are more flexible, and they can be improved by anyone. Sidewalk is committed to open standards and plans to continue using and contributing to open source projects whenever possible.

We are excited that there is already a growing community around the Public Life Data Protocol, which is at the center of CommonSpace. CommonSpace is free for anyone to use and modify for any purpose under the Apache 2.0 license. An issue list includes some features we think are the highest priority to add, but we are excited to see how the community builds upon CommonSpace!

If you’re a developer interested in contributing to CommonSpace, please visit

From Jan and Ingrid sitting on the steps of Sienna’s plazas, to the founding of the Gehl Institute, to the creation of the Public Life Data protocol, we see CommonSpace as another step in an exciting trajectory towards the widespread adoption of public life studies. And, of course, we hope this tool helps cities and community organizations everywhere to create vibrant, people-centered public spaces — and stronger urban communities.