Something is thinning in public space. Pavements are still crowded. Parks still bustle. But if you look more closely – or, better still, if you measure it – the texture of our interactions has changed.
Together with colleagues at Yale, Harvard and other universities, we used AI to compare footage of public spaces from the 1970s with recent video in the same locations in New York, Boston, and Philadelphia. The findings are striking: people walk faster, linger less, and are less likely to meet up. That’s no surprise in a world where phones, Netflix and AI companions are luring us away from real-world spaces and real-world friends. Yet, if technology is part of the problem, it may also be part of the solution. By using AI to study urban public spaces, we can gather data, pick out patterns and test new designs that could help us rethink, for our time, our modern versions of the agora– the market and main public gathering place of Athens.
The urban playground has always drawn curious minds. Among the sharpest was William “Holly” Whyte, who filmed plazas and parks in 1970s New York. He was fascinated by where people chose to sit, how they navigated space, and what drew them together. His findings, documented in The Social Life of Small Urban Spaces (1980), were at times beautifully simple: “What attracts people most, it would appear, is other people.” From his footage, Whyte turned his observations into data-backed recommendations: he said seats should be “two human backsides deep” and sung the praises of movable chairs that let people chase sun or shade. His analysis helped save New York spaces such as Bryant Park and shaped our modern approach to people-centred design.
Whyte’s experiments were revelatory, but hard to replicate. Why? Analysing the footage, frame by frame, took a team of assistants months. Now, finally, that challenge has been overcome, as we have invented non-human evaluators. Our team digitised Whyte’s original footage and compared it with recent videos – of Bryant Park, the steps of the Met Museum in New York, Boston’s Downtown Crossing, and Philadelphia’s Chestnut Street – collected by sociologist Keith Hampton. Then we trained an AI model to analyse the two sets of footage. AI allows self-driving cars to recognise bikes and pedestrians; that same technology excels at analysing footage of parks and plazas, and keeping track of hundreds of people at the same time. What took Whyte months now takes minutes.
The Metropolitan Museum of Art, New York. Photograph: Batchelder/Alamy
So how have cities changed between 1970 and 2010? As we discuss in a recent paper in the proceedings of the National Academy of Sciences, walking speeds have increased by 15%. People stand still less often. Dyads – pairs meeting and then walking together – have declined. Downtown Crossing in Boston, once lively and social, has become a pass-through. Even in Manhattan’s Bryant Park – improved, according to Whyte’s vision – the number of social interactions has fallen. Cities have not emptied, but a part of their essence has thinned.
Different forces have caused these changes. Work rhythms are accelerating and as time becomes more precious, we are less willing to spend it meandering. Perhaps people prefer Starbucks to the park. The iPhone was barely three years old in 2010, yet already we may have been pulled into our personalised data streams, abandoning the wandering gaze of the flâneur.
That could be a disaster for our social fabric. Online, we drift into curated echo chambers, scrolling past discomfort and filtering out dissent. Public space, by contrast, remains gloriously unfiltered. It invites friction, messiness, surprise. A rival football fan holds the door for you. Your children play with children who speak different languages. If we spend less time in public space, we might lose tolerance for the wider public – and thus lose the habit of citizenship itself.
Paradoxically, the same technologies pulling us inward might help bring us back out. Social media is addictive because algorithms are constantly testing out what we like. If we use AI to analyse outdoor public spaces, we can do the next best thing: give every park, plaza and street corner its own, personal William Whyte to test improvements there. What types of chairs and benches best promote interaction? Could adding greenery or water features create a more comfortable microclimate? Which public games might help break the ice? Temporary design interventions could be introduced, evaluated with AI, and iterated through a process of trial and error – evolving organically, much like nature itself.
To this end, architects should not shy away from using new AI tools, as we argue at this year’s Biennale Architettura in Venice. But how?
First, with humility. Public spaces of the past were far from perfect – often excluding women, minorities, and those with access needs. We should not romanticise them. Nor should we surrender to a technology-led present. Optimising public life through data alone risks repeating the mistakes of high modernism. AI can reveal patterns. It cannot dictate what is good.
Second, with curiosity. Public space is not static. It is alive. It responds to heat, light, geometry, programme. Small interventions – a bench in shade, a water fountain on a hot day, a winding path instead of a shortcut – can transform behaviour. In a recent study in Milan, we found that compliance with 30km/h speed limits had less to do with signage and more to do with street geometry. What slows us down is not instruction but design.
Climate change, too, plays a growing role. As temperatures rise across southern Europe, many urban spaces remain shaped by outdated climatic expectations. Sicily can now grow mangoes, yet its squares offer little protection from heat. We might learn from cities such as Singapore, where the orchestration of vegetation, water, and shading are used to actively mitigate heat. If Europe’s climate is changing then its public spaces must follow.
The deeper challenge is this: for too long, designers have worked at a remove – imagining how people should behave from studios located far from the street. Today, we have tools to observe how people actually behave. To test hypotheses. To prototype joy and proximity. Yet these tools must be used not for optimisation but for stewardship.
If we can use them wisely, we can counter the hollowing of public space. The agora isn’t dead. It just needs redesigning. And if we’re smart about it, AI might just help us get there. It may help us hear something else too: the fragile, elusive symphony of the commons.