Uneven sidewalks and sketchy intersections pose threats to all pedestrians, but they can be especially hazardous for people who have vision impairments or mobility issues. A new app from Carnegie Mellon University aims to solve this problem by interacting directly with traffic signal systems at intersections to help pedestrians safely get from point A to point B.

The app, called PedPal, represents a collaboration between the Intelligent Coordination and Logistics Lab in CMU's School of Computer Science; Rapid Flow Technologies, a CMU startup recently acquired by Miovision that provides complementary real-time traffic signal control technology; and pathVu, a University of Pittsburgh startup that aggregates sidewalk data for improved mobility and accessibility. PathVu's API knows the condition of sidewalks and curb ramps and provides step-by-step directions to PedPal for the most accessible route a pedestrian can take to a given destination.

Once a pedestrian reaches an intersection with a signal, CMU's intelligent intersection technology takes over to help the pedestrian cross the street. According to Stephen Smith, the lab director and a research professor in the Robotics Institute, the app first solicits the desired crossing direction and communicates the time the user needs to cross to the traffic signal control system. Then, during crossing, the app monitors the pedestrian's progress and interacts with the lights accordingly. If a pedestrian is crossing more slowly than anticipated, for example, the app can request more crossing time from the lights. If a pedestrian starts moving toward one side of the crosswalk or the other, the app will notify them and help them correct their course.

"The longer-term vision for this partnership between pathVu and CMU is to integrate the two technologies, working toward what is called the complete trip — where going from A to B you can know that the route is both safe and accessible for the pedestrian," said pathVu CEO Eric Sinagra.