CMU, Pittsburgh’s Surtrac program aims to ease traffic congestion

“At the city, we have to be careful about not putting something in that’s not thoroughly tested,” Purcell said. “We have to make sure everything we put on the street is going to work all the time.” CMU’s studies on the East Liberty intersections show vehicles spend 40 percent less time idling and reduce emissions by 21 percent. Other partners in the installation include the Southwestern Pennsylvania Commission Regional Traffic Signal Program and CMU’s Traffic 21.