Under the Phoenix sun: How to fix deadly-hot bus stops

On a summer day in the Sonoran Desert, as temperatures often climb to 110 degrees, waiting for a bus can be uncomfortable — even deadly. At least 21 people died from heat exposure at bus stops in Phoenix, Arizona in 2023, according to data from the city’s health department. 

A little more than 4,000 bus stops dot Phoenix. Currently, 77.5% of these stops have shade structures, according to the Phoenix transit department, which has pledged to add shade to each structure by 2050. 

Adding shade can reduce a metric called the “physiological equivalent temperature,” or PET — how hot a person’s body feels. But a recent study from the University of Texas Health Science Center at Houston found that not all shade structures are created equal. 

Assessing the current shade structures 

In 2017, the city of Phoenix partnered with Arizona State University students to redesign its structures. Using perforated steel panels, the final design optimized ventilation to reduce heat retention, city spokeswoman Carmen DeAlba Cardenas told Straight Arrow News. It also protected against vandalism. 

The design won an award, and the city began the manufacturing process. 

However, a 2021 ASU study raises questions about their efficacy. Bus stops with shade reduced the PET by as much as 38 degrees, but the problem was far from solved. 

Even in the shade, the mean PET score was 113 degrees — nearly 13 degrees higher than the “acceptable thermal comfort threshold,” according to the study. Roughly half of the surveyed riders reported feeling “hot or very hot.” 

When man-made surfaces like concrete and metal benches were exposed to afternoon sun, the study found their temperatures climbed to 111 degrees or higher, meeting or exceeding the “skin-burn threshold,” the point at which skin burns can occur. 

Psychology also played a part in the study. Riders waiting at more “beautiful” bus stops said they felt cooler, even when there were no clear improvements in the surrounding microclimate. The phenomenon led researchers to suggest that aesthetic appeal, including structural design, art and vegetation, can influence a rider’s thermal sensations. 

A look at innovative strategies

Phoenix isn’t the only city trying to solve this complex problem. The city of Seville, Spain, is taking a futuristic approach. There, a pilot bus structure uses solar panels to power a passive cooling system that circulates water beneath the structure, cooling waiting areas by as much as 36 degrees. 

The structure costs about $30,566 when converted to U.S. dollars. In Phoenix, bus shelters cost $18,500, Cardenas told SAN. 

Florida is using AI to look to the future. Xiang “Jacob” Yan, an assistant professor in the University of Florida’s Department of Civil and Coastal Engineering, told SAN that he and his research team collect data from bus stops to assess which amenities are needed for upgrades. Recently, Yan’s team measured Miami bus stops and pedestrian paths connecting to transit stops with what they called a “Transit Heat Exposure Index” to determine how hot it gets for people waiting for public transit. 

Yan told SAN that when cities like Miami identify the bus stops most likely to expose people to unsafe heat levels, they can work with partners to add shelters and tree canopies along pedestrian paths. 

Evidence in the desert 

Arizona State University collaborated with 3M to test a reflective film on bus shelter roofs in Tempe, a suburb just outside Phoenix. The material reflected the sun’s energy and radiated its heat skyward, cooling the area beneath. Bus riders under the shelters with film felt 2-4 degrees cooler than under the control shelters without it, ASU found. 

Though the results held promise, Tempe officials told SAN they paused further testing to focus on installing additional shelters at unshaded spots due to limited resources. 

Phoenix’s light rail system, operated by Valley Metro, offers a model that other local officials have looked toward. Shade structures at light rail stops have both vertical and horizontal components, which allows “for more shade in the late afternoon and also in the morning times,” Valley Metro planner Arden Holloway told SAN. 

Valley Metro stations also incorporate drought-resistant trees and vegetation. 

The light rail stops are fewer and farther between than bus stops, with only 28 across the metro area, compared with “thousands of bus stops,” Holloway said. Therefore, she said it’s important to note “it’s a lot more money and more strain on the budget to consider allocating resources to every single bus stop.”

What the city is doing

Phoenix public transit is not currently planning any new bus shelter pilot programs focused on heat reduction strategies at bus shelters. Instead, Cardenas told SAN the city is evaluating a “wide range of shade and heat mitigation strategies for outdoor environments” through engagement with Smart Surfaces Coalition and the National League of Cities. 

Valley Metro and the city have partnered to provide information to transit users about where to find cooling and respite centers, as well as locations for water, Valley Metro spokeswoman Susan Tierney told SAN. The light rail provider also distributes fans and sunscreen, and educates frontline staff on how to recognize heat illness. All in, the city spent about $3 million on broader heat response programs last summer.

One of Valley Metro’s recent improvements is better air-conditioning in the bus fleet, as well as an app that provides real-time arrival schedules for the buses. 

“We advise people to time the arrival of a train or a bus so that they are limiting their wait outside,” Tierney said. 

A strained system

Heat-related emergency calls at bus stops often involve individuals who have been using drugs or alcohol. In 2023, 17 of 21 deaths recorded at bus stops — 81% — involved substance use, according to city data. That’s well above the rate for heat deaths overall that year. City data showed 51% of the valley’s overall heat deaths involved substance use. 

The majority of deaths happened in June-August, with 78% occurring when the temperatures rose to 110 degrees or greater. 

A regular bus rider, Steve Drotman, 84, began taking public transit a decade ago, when his vision waned and he could no longer drive. He is careful to choose morning routes, wear a wide-brimmed hat and avoid the worst of the afternoon sun. 

Sometimes, Drotman misses the bus and has to wait 30 minutes for the next one, leaving him to scout for shade. Despite the challenges, he remains loyal to public transit. 

“I love every day that I get on the bus,” he told SAN.

Others are not as positive about the city’s bus system. Riders complain that buses can arrive late or never at all, leaving them stranded for an hour or more. 

It’s also not always the speediest option. According to Valley Metro, it takes about 91 minutes to travel from one end of the line to the other, covering 28 miles. That same distance can often be traveled much faster by car. 

And there’s a stigma surrounding Phoenix’s public transportation, that it’s for the “poorest of the poor,” as one rider wrote. Many also note the growing number of unhoused people seeking refuge at bus shelters, forcing actual bus riders to wait in the heat. 

Phoenix’s vision would mean better outdoor infrastructure

In a city that runs on air conditioning and car culture, people who rely on public transit can be overlooked. Still, Phoenix’s fixed-bus routes logged more than 28 million boardings in the 2025 fiscal year. City leaders envision a future where 40% of the population will choose alternative transportation, including public transit, walking and cycling. 

Phoenix wants to become the world’s most sustainable desert city by 2050. This includes doubling the current tree and shade canopy to cover 25% of the city’s area.

That’s by design: UTHealth Houston researchers found that trees provided “greater cooling benefit than shelters and were associated with lower risk of extreme and high heat threat safety levels than areas without tree shade.”

During Arizona’s record-breaking 2023 summer, a study conducted in Tucson recorded ground temperatures at various bus stops around 2 p.m. and found stark differences. In areas lacking shelter, vegetation and tree shade, ground temperatures reached 124 degrees. Bus shelters with tree shade reached 108 degrees. That 16-degree divide can be the difference between survivable and intolerable heat for those waiting at bus stops.

“Every action is a climate action,” the Phoenix Climate Action Plan said. “Our climate strategies must use this logic to understand the potential impacts, both positive and negative, direct and indirect, on overburdened and disproportionately impacted communities.”