Waiting at a bus stop on a hot summer day can be uncomfortable, even dangerous.
While shelters are meant to protect riders from the heat, new research from UTHealth Houston reveals that some shelter designs might actually make things worse.
The study, published in Transportation Research Part D, looked closely at how different types of bus stop shelters and nearby trees affect heat stress—the strain the body feels from high temperatures, humidity, sunlight, and wind.
According to lead researcher Dr. Kevin Lanza, most people assume that standing under a shelter automatically helps cool you down, but that’s not always true.
Dr. Lanza explains that heat stress isn’t just about the temperature you see on your phone. If the sun is strong and directly shining on you, your body continues to heat up.
In severe cases, standing in the heat for too long—like while waiting for a late bus—can lead to heat stroke, a serious and potentially deadly condition.
The research team studied 17 bus stops around Houston during a particularly hot period in the summer of 2023, when temperatures ranged from 95 to 103 degrees Fahrenheit.
Using high-tech sensors, they measured something called the wet bulb globe temperature (WBGT), which gives a fuller picture of heat stress by combining temperature, humidity, sunlight, and wind.
On average, the hottest spots without shade showed a WBGT of 92.5 degrees, which is considered dangerous. However, when shade from trees was available, the WBGT dropped by nearly 6 degrees. Shelters also helped, but not all were equally effective.
One of the best-performing shelters had a stainless steel frame with glass sides and a glass roof, which brought down the heat stress level by 5.9 degrees. But another common design—with an aluminum frame, acrylic walls, and a domed roof—only lowered the heat by 1.6 degrees. Surprisingly, one shelter actually made conditions worse. Its enclosed acrylic walls and metal frame trapped heat inside like an oven, making it 5.2 degrees hotter than standing out in the open.
Dr. Lanza said the findings show the importance of shelter design and tree planting. Trees consistently provided the best relief from heat, but if trees can’t be planted, it’s crucial to build shelters that allow heat to escape and don’t trap sunlight.
This research could help cities across the country create safer, more comfortable public transit spaces, especially as summer temperatures continue to rise. For the millions of people who rely on buses, getting some shade should bring real relief—not make the heat even worse.
