Crossing urban streets can be dangerous for people who are blind or visually impaired, but a new smartphone app in development at the University of Minnesota could make it easier and safer.

Recent trials conducted in downtown Stillwater found the app, called PedNav, was about 95% accurate in accessing traffic signal control systems and sending correct auditory and visual messages to tell pedestrians when it was safe to cross the street.

The app remains in the research phase and is unavailable to the public. But its deployment could be a game-changer for anybody with a visual impairment or other condition affecting mobility, said Kate Grathwol, president and CEO of Vision Loss Resources in the Twin Cities.

"To navigate safely, you need to know where you are, how to find a button to get a walk sign and when traffic is moving in your direction," she said. PedNav "is like Google Maps for the visually impaired.'

A pedestrian arriving at an intersection points their smartphone at a crosswalk and taps it once to get their location and information about the street, such as "heading west to cross Washington Street, four lanes," said Chen-Fu Liao, lead researcher in the Department of Mechanical Engineering at the U. A second tap allows the phone to communicate with the traffic control signal, which returns visual images and text-to-speech messages to guide pedestrians through intersections.

Visual messages feature a green man walking when it's safe to cross, accompanied by audio messages such as "walk sign is on, 20 seconds to cross." PedNav displays a red hand when it is not safe to cross.

"Time is important information," Liao said. "Can I make it or should I stop? Do I have sufficient time to cross? This helps anybody with visual impairments or low vision when they can't see a walk sign."

U researchers teamed up with the Minnesota Department of Transportation (MnDOT) to test the app by placing beacons on traffic control boxes at six intersections in Stillwater, chosen because it could replicate an urban area. The test allowed MnDOT to learn more about programming signals, which will have to get smarter to send out more messages in the future with the arrival of autonomous vehicles, said Mike Fairbanks, MnDOT's metro signal operations engineer.

"It showed MnDOT is dedicated to pedestrian safety, including those with visual impairments," he said. "I think it is technology those with visual impairments would embrace."

PedNav could benefit a growing number of people who experience vision loss or blindness. A 2018 National Health Interview Survey found 32.2 million Americans 18 and older reported experiencing vision loss. In 2016, about 3.3% of Minnesota residents 18 and older — about 140,000 people — reported difficulty seeing. About 5% of residents 65 and older have vision loss, a significant number because 1 in 5 residents in Minnesota will be in that age range by 2030, Grathwol said.

About 80% of sensory information is absorbed through the eyes, "and the brain gets panicky when we can't see," she said. Technology like PedNav would be beneficial in breaking down barriers and making cities more walkable for everybody, she said.

"Nobody heard of curb cuts until the American with Disabilities Act," Grathwol said. "Now Rollerbladers, moms with strollers, the elderly with groceries and wheelchairs that take longer to cross the street use them. This technology [PedNav] will change lives for long time."

Tim Harlow • 612-673-7768