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Connecticut’s First Adaptive Traffic Signal System Deployed
Publication Date
April 29th 2022, 11:00 am

Urban Engineers provided design and construction support for this project that includes new cutting-edge technology aimed at mitigating traffic and improving air quality


greenwich intersection ribbon cutting 1

(from right to left) Town of Greenwich First Selectman Fred Camillo, Town of Greenwich Department of Public Works Deputy Commissioner Jim Michel, Town of Greenwich Department of Public Works Senior Civil Engineer and Project Manager Gabriella Circosta Cohee, NY-Conn Corporation Vice President Ross Rizzo, Town of Greenwich Department of Public Works Traffic Operations & Maintenance Foreman Sean Turpin, NY-Conn Corporation Project Manager Andy Mastrogiannis, Town of Greenwich Department of Public Works Commissioner Amy Siebert, Urban Engineers Project Engineer Dane Greene, and Urban Engineers Vice President Jason L. Cardinal celebrating the completion of the Arch Street Corridor Traffic Improvements Project at the ribbon cutting ceremony on April 26, 2022. Credit: Renee Wallace, Town of Greenwich

Connecticut’s first adaptive traffic signal system is officially activated at five signalized intersections on Arch Street to help improve traffic flow, decrease travel time, reduce congestion, and lower vehicle emissions on a road used by approximately 35,000 vehicles daily. Urban Engineers provided the original design work for the project – including plans, specs, and estimates – and was subsequently retained to provide construction support.


“We are excited to celebrate the completion of this project that is immediately reducing congestion and improving air quality in Connecticut with less power consumption,” said Jason Cardinal, PE, CCM, an Urban vice president and New England regional manager. “This project is a true success and team effort, led by the Town of Greenwich’s Gabriella Circosta Cohee with support from Urban’s traffic design team and construction support staff, as well as the folks from the NY-Conn Corporation.”


The Arch Street Corridor Traffic Improvements Project installed cutting-edge cameras and signal controller software to collect and analyze traffic data on directional traffic flow, vehicle delay, and lane queue length.  The intelligent signal controller software receives the current traffic information provided by the cameras and automatically optimizes the traffic signal timing. Each traffic control box communicates with each other in real-time through a fiberoptic network loop. 


“Adaptive Signal Control Technology (ASCT) makes traffic signals more effective and efficient. Unlike traditionally timed traffic signals, ASCT accommodates changing traffic patterns and calculates a traffic signal timing plan based on the changing traffic conditions on the roadway caused by traffic crashes, special events, road construction, and other roadway incidents in real-time,” said Gabriella M. Circosta Cohee, P.E., Town of Greenwich Senior Civil Engineer and Project Manager. “The new adaptive traffic signal system can detect an influx of vehicles and can improve the traffic congestion by instantly adjusting the timing of the traffic lights at all five intersections.”


According to the U.S. Department of Transportation Federal Highway Administration adaptive signal control technology can:


  • Automatically adapt to unexpected changes in traffic conditions
  • Improve travel time reliability by progressively moving vehicles through green lights
  • Reduce congestion and fuel consumption by creating a smoother flow
  • Prolong the effectiveness of traffic signal timing
  • Decrease vehicle emissions of hydrocarbons and carbon monoxide due to improved traffic flow
  • Continuously distribute green light time equitably for all traffic movements


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Construction of Arch Street Corridor traffic improvements Credit: Renee Wallace, Town of Greenwich

In addition to installing the first adaptive signal, this project also introduced the first yellow flashing arrow in the state. The flashing yellow arrow is a new type of signal located in a dedicated left-turn lane at a signalized intersection and signifies yield to oncoming traffic and then proceed with caution. This alleviates traffic and queue time by allowing vehicles to turn when there is no traffic in the opposing direction. Prior to the flashing yellow arrow, motorists had to wait for the green light.


“When DPW embarked on this project several years ago, we knew there was significant traffic in this corridor that was due to the Train Station, I-95, the proximity to downtown, the Bruce Museum, Bruce Park and especially Roger Sherman Baldwin Park. We knew we had to look into the future to see if there is new technology that could be used to improve traffic flow. In reviewing several different options, we decided that Adaptive Signal Technology was the best option for this location,” said Town of Greenwich Department of Public Works Deputy Commissioner Jim Michel. “We are excited to be a leader for the State of Connecticut in implementing new and advanced infrastructure that can decrease vehicle emissions and improve air quality. This project is an example of how the Department of Public Works can make a positive impact for our residents today and for future generations to come.”


The five signalized intersections are located at Arch Street and Railroad Avenue, Arch Street and Horseneck Lane, Arch Street and I-95 southbound ramp, Arch Street & I-95 northbound ramp and, Arch Street and Steamboat Road/Museum Drive. The new traffic lights, control boxes and pedestrian signals are more efficient and use 66 percent less energy. This project received $2.75 million in funding through the Federal Highway Administration’s Congestion Mitigation and Air Quality (CMAQ) program.


Urban was involved with the project from its start. During construction, the firm redesigned two of the intersections as additional unforeseen field conditions changed the design. Urban staff prepared construction plans and were involved during all of the construction meetings.