What if an omnipresent cop were directing traffic, aware of all flows and bottlenecks, moving people walking and in vehicles to their destinations as rapidly as possible?
In Pittsburgh, the next best thing is happening: an array of sensors, in conjunction with machine learning, is directing traffic signals to keep cars and people flowing.
Named the Scalable Urban Traffic Control, or Surtrac, the system is already reducing overall travel time (that is, time spent getting to destinations) by 25 percent, time spent waiting at intersections by over 40 percent, stops that cause wear on roads and tires by 30 percent, and emissions that harm human and planetary health by 20 percent. As the website puts it, Surtrac uses “research from artificial intelligence and traffic theory” to optimize “the performance of signals for the traffic that is actually on the road, improving traffic flow.”
The system does so by using multiple “eyes,” many previously operating, including cameras and radar. It then times signals to maximize traffic flow—or, depending on how it is programmed, to maximize the flow of people, including those in buses, on bikes, even on foot.
Ensuring equity for people on buses, bikes, and foot
This might seem to be a win-win situation, but a question springs to mind for those of us concerned with sustainable transportation. What if this remarkable traffic system leads to a “rebound” effect, in which, as traffic moves more smoothly, more people drive until the system returns to its previous state? Such induced traffic invariably happens when roads are widened, resulting in more and more solo car trips.
To find out more, I spoke to Karen Lightman, Executive Director of Metro 21 at Carnegie Mellon, which partners with the City of Pittsburgh and an array of other municipalities and institutions to create and deploy Surtrac.
Lightman put creating an environment that’s safe and efficient for pedestrians and bicycles, and that prioritizes buses, front and center. Regarding the latest iteration of Surtrac, in Pittsburgh, she explained that “people are the rulers of downtown. Cars come after the people, and so the focus will be on insuring safety for the pedestrians.”
Ultimately, however, Lightman pointed out, it comes down to policy, which is driven largely by values. Metro 21 and its partners can provide the technology, they can predict likely outcomes of different priorities, but it’s up to policymakers—and the public—to decide how to deploy it. “We show what the technology is capable of, and then it’s up to the policy folks and the government folks. They decide this is a priority,” whether it’s bicyclists, buses, or cars.
As one example, if a bicyclist is approaching an intersection at 20 miles per hour, the technology can be programmed to hold the light for an additional 2 seconds to let her pass. Bus priority is also developing rapidly, with obvious benefits for moving the most people in the shortest time.
Lightman hopes Surtrac, or similar technology, will be central to multimodal smart cities of the future. The Pittsburgh system had already been growing swiftly, from a 2012 pilot deployment at nine intersections, to 50 intersections from 2014-18, to an expected 150 intersections powered by a $29 million grant from the U.S. Department of Transportation, from the City of Pittsburgh, and from the state of Pennsylvania.
Community input makes technology work for people
The issue of pedestrian access came up early in Surtrac’s deployment, when people walking reported that they were stranded interminably waiting for traffic signals optimized for cars. Since the technology is iterative, it can learn to enable individual pedestrians who might need just a bit more time to cross the road.
Rapid input from local community partners allowed Surtrac’s operators to respond quickly to early problems for people walking. Indeed, Lightman emphasized, Surtrac would not be nearly as effective without multiple partnerships, including city governments, citizen groups, and businesses. An associated company, Rapid Flow technologies, was formed to deploy the technology.
As one example of community involvement, Lightman points to a partnership with the Pittsburgh School for the Blind, to “connect the traffic signalization with buses and people who are visually impaired.”
Sharing data is another key priority for Metro 21. “We’re really big on open data,” said Lightman, pointing to a partnership with the Western Pennsylvania Regional Data Center, which provides accessible information on transportation, mobility, parking, real estate, and related issues. This means that researchers, businesses, and governments are not operating blind when developing a transportation project, but can begin with quality data from the real world.
The smart city of the future is almost here
Data is the lifeblood in connecting transit to all aspects of city life. “Now that we’re using technology to address traffic,” Lightman asked, “what about everything else? If you can’t breathe the air, if the water quality is poor? If you’re dealing with cars it’s usually an equity issue.” She also mentioned potholes, air quality, and emergency medicine among a host of related issues, all connected to transit access.
Mobility 21 and Surtrac are part of an ongoing project to address transit, and its many related issues, with the latest technology. “We use the city as a test bed, and the city uses us as their R & D arm,” said Lightman. If all works out – and that means smart policy – not just smart technology – Surtrac may be opening the door on the smart city of future in which platoons of bikes, small electric vehicles, pedestrians, buses, and trains enact a dance of perfect harmony. It will be a city where even the humblest resident gets safely and efficiently to her destination at all hours.
If the 1950s myth of a car zooming down the open road has long faced the reality of jammed freeways, the smart city of the near future may be the site of real freedom, real mobility, for all.
Photo of people walking on the Roberto Clemente Bridge in Pittsburgh by Britt Reints