Index Measures Impact of Heat on Pedestrian Activity

When heat and humidity are high, people are more likely to opt for cars when possible.

1 minute read

June 26, 2025, 9:00 AM PDT

By Diana Ionescu @aworkoffiction


Man walking down city sidewalk with sweat on back of his t-shirt on hot day.

Aleksandar / Adobe Stock

New research from MIT finds that, unsurprisingly, high heat and humidity encourage people to choose to drive for trips that they would otherwise make by foot or transit.

As Christian MilNeil explains in Streetsblog Mass, the researchers calculated the influence of the “Universal Thermal Climate Index” (UTCI) incorporates wind speeds and radiant temperatures (“which vary according the amount of shade and heat-absorbing materials, like hot asphalt”) into the traditional heat index measurement, which combines heat and humidity. 

This index is more accurate to how people make choices about their travel based on perceived discomfort. As one researcher explained, “What that means is, if I am walking along a street, and there’s a 1 degree increase in perceived temperature, that block is going to feel like a longer walk, 81 meters longer, because it's hotter.”

The results have implications for policymakers and planners who want to encourage people to walk and use transit. Shade, cooling pavement, and other infrastructure interventions can increase the distance that people are willing to walk and make cities safer and more comfortable.

Wednesday, June 25, 2025 in Streetsblog Mass

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I love the variety of courses, many practical, and all richly illustrated. They have inspired many ideas that I've applied in practice, and in my own teaching. Mary G., Urban Planner

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Index Measures Impact of Heat on Pedestrian Activity

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