Signal Spotlight: Norwalk’s New Adaptive Traffic Signals

The City of Norwalk has begun to implement new “Adaptive Traffic Signals” that will automatically adjust the cycle length and distribute green light time. The system will accommodate changing traffic patterns and helps ease congestion.

What are adaptive traffic signals?

Adaptive Traffic Signals adjust the timing of their green light cycles to match current traffic conditions on the roadway. The system constantly collects data of approaching vehicles and creates new timing sequences and adjusts accordingly. The signals will change based on traffic patterns in the area rather than a standardized shift from red to green.

The main benefits of adaptive signal control technology over conventional signal systems are that it can:

1. Automatically adapt to unexpected changes in traffic conditions.
2. Continuously distribute green light time equitably for all traffic movements.
3. Improve travel time reliability by progressively moving vehicles through green lights.
4. Reduce congestion by creating smoother flow.

The City of Norwalk began to imagine a citywide Traffic Adaptive System program in 2018.

The 1^st phase of the Adaptive Signal System was completed in 2019 with implementation of 8 adaptive traffic signals on West Avenue as part of the SoNo Collection project.

The 2^nd phase of the Adaptive Signal System will add 8 more signalized intersections on West Avenue and Belden Avenue to the Adaptive Signal System Network under LRARP funding. This project will be completed by the end of 2022.

The 3^rd phase of the Adaptive Signal System will add another 14 signalized intersections in South Norwalk on MLK, South Main Street and North Main Street to the Adaptive Signal System Network as part of the Walk Bridge project. This project will be completed late this year or early next year.

The 4^th phase of the Adaptive Signal System will add 3 more signalized intersections on East Avenue to the Adaptive Signal System Network as part of phase 4 traffic signal upgrade under CMAQ founding. This project will be completed by the end of 2023.

The 5^th phase of the Adaptive Signal System will add 21 more signalized intersections to the Adaptive Signal System Network. These signalized intersections are located on Route 1, East Avenue, Martin Luther King Boulevard, and South Main Street. This project will be built under the recently awarded CMAQ founding. The estimate time of completion is the end of 2024.

The City’s goal is to complete the Traffic Signal Adaptive System project by the end of 2025.

Along with implementing the Adaptive Signal System, the exclusive pedestrian crossing phase will be replaced with concurrent phasing and the LPI (Lead Pedestrian Interval) where appropriate. As part of these changes, all regular pedestrian push buttons will be replaced with an (APS) audible push button system.

Fred Eshraghi
City Traffic Engineer
City of Norwalk