Some bus stop shelters, designed to protect transit users from extreme weather, may inadvertently increase heat stress during hot weather. This finding comes from a study led by UTHealth Houston and published in Transportation Research Part D: Transport and Environment.
Public transportation is often seen as a cost-effective and environmentally friendly alternative to car commuting. However, extreme summer temperatures can make waiting for public transport challenging. According to Kevin Lanza, PhD, assistant professor at UTHealth Houston School of Public Health, "Heat stress is a combination of factors, not just the temperature you see on your phone’s weather app or your car dash."
The study examined 17 bus stops in Houston over 13 days with temperatures between 95 to 103 degrees Fahrenheit. Researchers used sensors to measure wet bulb globe temperature (WBGT), which considers air temperature, humidity, wind speed, and solar radiation. They found that unshaded areas recorded an average WBGT of 92.5 degrees, indicating significant heat stress risk.
Providing shade significantly reduced WBGT at these stops. On average, trees lowered WBGT by 5.9 degrees. The research team evaluated four shelter designs; the most effective was a stainless steel frame with glass sides and roof, reducing WBGT by 5.9 degrees.
However, another design with acrylic walls trapped heat inside the shelter. Lanza noted that "it was like an oven," making it hotter than outside the shelter. He suggested that planting trees or strategic shelter design could mitigate this issue.
Co-authors include Baojiang Chen, PhD; Sara Ernst; and Katie Watkins.
