From the years 2012 to 2016, Surtrac was deployed at 50 total intersections across several neighborhoods in the city of Pittsburgh, Pennsylvania.
All of these intersections were using conventional coordinated, fully actuated control, and most of them had new timing patterns installed. When compared to the previous systems, Surtrac helped reduce travel time by 26%, number of stops by 31%, wait time at intersections by 41%, and emissions by 21%. A separate study by an unrelated third-party also showed safety improvement after the installation of Surtrac, with reductions in both total and fatal crashes by 13%-36%.
These 50 intersections are in diverse city environments with extremely tight and complex urban grid networks where major crossing streets require optimal switching and queue management service. One section of the deployment, in the East Liberty neighborhood, includes three major roads all converging in a triangle, with the dominant traffic flows changing throughout the day. One of these intersections, in a very mixed-use neighborhood consisting of retail stores, office buildings, a lot of pedestrian, bicycle, scooter and other multi-modal traffic, averages about 35,000 vehicles per day. Surtrac is also deployed on less complex single and double arterial corridors where precise coordination along the full length of the corridor, while still providing adequate service to side streets, is required.
FIGURE 1: Surtrac deployment in Pittsburgh, PA
Regardless of the environment, Surtrac quickly and automatically adapts to such diverse types of networks, in real-time, as traffic patterns change. Even more, over a longer time horizon as city neighborhoods naturally evolve, Surtrac adapts to an ever-changing number of factors causing congestion.
Parts of this project included extensive equipment upgrades, including new cabinets and controllers, broadband radio networking between intersections, and dedicated short-range communication (DSRC) radios. Detection types in the network are split, with about half of the intersections using video detection and the other half using radar.
This project, at various stages, was a collaboration between the City of Pittsburgh, the Southwestern Pennsylvania Commission (Pittsburgh’s metropolitan planning organization or “MPO”), PennDOT, and several Pittsburgh area neighborhood and citizen advocacy organizations. The funding was provided by several local non-profit foundations including the Hillman Foundation, the Heinz Endowments, and the R.K. Mellon Foundation.
This was truly a collaborative effort that required extensive coordination and responsiveness to numerous diverse stakeholders with varied priorities. The major goal of the initial deployment was reducing emissions. Within the first year, the goals broadened to include multi-modal transportation and improving neighborhood livability. As the deployment expanded, distinct characteristics of each neighborhood and constituent groups were considered during implementation. For example, transit is an essential component of this network, so in cooperation with the Port Authority of Allegheny County, continuing innovation focusing on using connected vehicle technologies to help move transit even more efficiently, which will benefit all travelers, has become a core focus. Further, in collaboration with Carnegie Mellon University, Rapid Flow has been supporting traffic signal communication solutions for older adults and individuals with disabilities, including those with vision, hearing, or mobility impairments. For example, Surtrac allows pedestrians to communicate directly with the intersection to request longer crossing times.
At various stages of this project, Rapid Flow helped secure additional funding, helped write the RFP to bid out the construction contract, worked with the contractor responsible for hardware installation (including defining detection needs and detection zone setup), helped configure communication between intersections, verified all communication and detection systems, and performed system verification.
Parts of this project won an ITS Pennsylvania Best of ITS award in 2015. Additionally, Pittsburgh has used its Surtrac and other smart city deployments in its marketing messaging as it competes with other cities to recruit businesses to the City (including Amazon’s HQ2 project), confident that Surtrac will help the City adapt to the increases in population and economic activity.
The deployment has been so successful that the City has plans to install another 100-200 adaptive control intersections in the city as part of a federal funding program. Some of these new intersections are focused on unique traffic congestion issues such as those associated with the City’s sports stadiums, concert venues, and other entertainment complexes.