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

Young Professional

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 and Environmental Planner

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 and Environmental Planner

Get top-rated, practical training for planners

"Planetizen federal action tracker" logo superimposed over black and white image of US Capitol dome.

Planetizen Federal Action Tracker

A weekly monitor of how Trump’s orders and actions are impacting planners and planning in America.

October 28, 2026 - Zachary Whalen

A car drives through a puddle, making a large splash. Rain pours down.

California plans to bury El Niño’s downpour

If the state plays its cards right, it may be able to store a billion acre-feet of El Niño’s water in aquifers.

October 28, 2026 - Grist

A pencil rendering of Foundry Park, which shows skyscrapers and public green spaces.

Chicago breaks ground on $3 billion megadevelopment

The new neighborhood, titled Foundry Park, will one day host 3,700 residences.

October 23, 2026 - Chicago Sun Times

A swamp in South Carolina with tall pale trees and Spanish moss in the water.

Satanic place names

From streams and lakes to valleys and canyons, I mapped more than 1,000 places named after the Devil.

October 31 - The Daily Yonder

A rendering of a high speed rain station in California, with wide platforms and a sleep train with yellow highlights.

California High-Speed Rail Authority CEO resigns after $600,000 scandal

Under Ian Choudri, the authority used taxpayer dollars to fund first class flights and trips to nightclubs.

October 30 - Cal Matters

 A bridge stretches across the Missouri River at Chamberlain, South Dakota.

Want to study the Missouri River? Soon, you may need unanimous approval from 10 states

Legislation would require 10 governors’ permission to study or build projects moving water outside the basin.

October 30 - South Dakota Searchlight