We go faster, continue less, and miss each other more

The city streets became less like town squares, but more like conveyor belts. A new study using computer vision and artificial intelligence shows that pedestrians in New York, Boston and Philadelphia are now walking 15% and walking 14% in public places, 14% less than in 1980.

This week Proceedings of the National Academy of SciencesThe study raises questions about how cities develop and what it means for social life, communities, and public design.

Forty years, four urban spaces have a major transformation

The research team—led by schoolers from MIT, Yale, Michigan State University, Harvard, and the University of Hong Kong—compared archive videos from urbanist William Whyte’s late-1970s fieldwork with matching footage filmed in 2010. The study focused on four iconic spots: Boston’s Downtown Crossing, New York City’s Bryant Park and the steps of the Metropolitan Museum of Art, and Chestnut Street in Philadelphia.

Using AI-powered computer vision models, the team measured walking speeds, patterns of social interactions, and how long people stayed in each location. Although some behaviors remain stable (for example, the proportion of people walking alone (67% in 1980, compared with 68% in 2010) has changed dramatically.

• Walking speed increased by 15%
• Lingering behavior dropped by 50%
• Group encounters become less: Only 2% of visitors joined a group in 2010, down from 5.5% in 1980

From the public square to the access

“Things have changed over the past 40 years,” said Carlo Ratti, MIT Practice Professor and Director of Sighable City Lab. “The speed we walk, how people meet in public places – what we see here is that public places work differently, more of a kind of access rather than a space to meet.”

It’s not just pace. This is also the purpose. Now, city dwellers tend to organize their gatherings over the phone, with the destination in mind. Wandering around, watching strangers or meeting friends (once the sign of city life) is rare. As Ratti observed, “When you look at William Whyte’s video, people in public spaces look at each other.”

Send text messages, Starbucks and the privatization of public life

The study floats some theories of social retreat from public spaces. The widespread use of mobile phones means people can coordinate gatherings or entertainment in advance, eliminating the spontaneity that once represented public squares. People may also avoid wandering outdoors and support the comfort of air conditioning.

The paper notes that “outdoor socialization may have changed the interior,” the paper notes that the spread of coffee shops is an alternative to sidewalks. Starbucks did not exist in 1980. Today, every neighborhood cafe offers Wi-Fi, exit and climate control, an attractive alternative to hard benches in the summer heat or winter monsoon.

New tools for urban design

Although the study describes past behavior, its implications are forward-looking. “Public space is an important factor in civic life,” said Arianna Salazar-Miranda, now co-author of Yale University. “The more we can continue to improve public spaces, the more we can make our city suitable for convening.”

The AI-driven approach also provides a new tool to understand how cities develop. Ratti and his colleagues are now analyzing videos of 40 squares in Europe to expand their findings.

“The question is: How can we learn more?” said Fabio Duarte of MIT. “This part is what we are doing.”

Public life in the fast lane

As sidewalks grow and squares become quieter, urban planners may need to rethink how to invite people to slow down and connect. Are we designing streets that bring people together, or are we taking them from point A to point B?

The city may still be alive, but its heartbeats are getting faster.

Magazine: Proceedings of the National Academy of Sciences
doi: 10.1073/pnas.2424662122

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