Smart traffic signals designed to improve the flow of traffic also could help pedestrians with visual or other disabilities safely cross streets, or even catch a bus.

Researchers at Carnegie Mellon University's Robotics Institute have begun a two-year project, sponsored in large part by a $2 million grant from the Federal Highway Administration, to develop a system that relays information from a user's smartphone directly to the smart traffic signals. The signals could adjust their timing to accommodate users who need extra time to cross.

"The smartphone can learn how fast the pedestrian moves, or if the user might have difficulty at certain intersections," explained Research Professor of Robotics Stephen Smith. "The intersection could extend the green in real time to give her the extra time she needs. And it might monitor the phone's location so that it notices if she starts moving outside the crosswalk."                   

With support from CMU'sTraffic21 andMetro21 initiatives, Smith previously led development of the Surtrac system of smart signals. The signals use artificial intelligence to monitor traffic. They can alter their timing to maximize the number of cars that can pass through an intersection and keep cars from idling needlessly at a stop light when no cross traffic is present.

In Pittsburgh, the adaptive traffic signal system has shown it can reduce travel time by 25 percent, braking by 30 percent and idling by more than 40 percent. A spinoff company, Rapid Flow Technologies, now manufactures and is further developing the signals, which have been installed at 50 intersections in Pittsburgh's East End. The company recently installed smart signals in Atlanta, with installations planned over the next year in at least two other cities.

Development of the system for people with disabilities initially will involve a set of existing smart signals on Pittsburgh's Baum Boulevard and Centre Avenue in the vicinity of the Carnegie Library for the Blind and Physically Handicapped. In the program's second year, two additional intersections will be equipped with smart signals to connect the system with the Western Pennsylvania School for Blind Children in Oakland.

The first year of the project will concentrate on developing a basic system for increasing the safety of street crossings, Smith said. In the second year, the researchers will explore what might be possible if pedestrians share their routes and destinations with the smart signals.

"With vehicles, we've shown that if drivers are able to tell us their routes, we can move them through faster," Smith said. "We propose we can do the same with the pedestrians by coordinating pedestrian and vehicle flows."

Smith added that it also might be possible to help users catch buses if the system knows which bus stop or what bus route they need.

Smith said he anticipates field tests each year involving 25 to 30 people with visual disabilities. Once developed, the system also should work for people with other sorts of disabilities. This capability eventually might be of use to all users, disabled or otherwise, such as in suburban areas where pedestrians might be infrequent and signals aren't timed to accommodate them, he said.

Smartphones will need to be equipped with dedicated short range communications (DSRC) radios to communicate with the signals. For the study, a DSRC sleeve can be fitted to existing smartphones, Smith said, but smartphones could eventually be equipped with DSRC radios if this application proves useful.

The project is supported by the Federal Highway Administration's Accessible Transportation Technology Research Initiative, with additional aid from the City of Pittsburgh, Port Authority of Allegheny County, Rapid Flow Technologies and others.