Green Wave

Traffic Signal Synchronization is a traffic engineering technique of coordinating the green light times for a series of intersections to enable the maximum number of vehicles to pass through, thereby reducing stops and delays experienced by motorists.

As a driver it can be frustrating to stop at multiple signals along an arterial street. No sooner do you get your speed up and into the flow, and another red light brings you to a stop. As part of ongoing efforts to reduce congestion, the City has implemented updated traffic signal timing that will provide improved signal synchronization. The goal is to synchronize the signals so that drivers have a greater probability of getting a green light before they arrive at the next signal, reducing the number of times they have to stop.

Synchronized signal timing was previously implemented within the City of Elk Grove during the year 2020 and was referred to as “Green Wave”. This project included synchronization for Laguna Boulevard and Elk Grove Boulevard between Bruceville Road and Elk Grove Florin Road.

The City of Elk Grove’s newest project, “Green Wave Phase 2”, implements timing changes for traffic signals along Elk Grove Boulevard and Laguna Boulevard between Interstate 5 (I-5) and Bruceville Road. This signal timing adjustment allows drivers traveling near the posted speed limit to have a higher probability of arriving at an intersection on a green light and reduce the number of red lights encountered. It is important to keep in mind that coordination on the main roadway may cause side streets and left turns to have longer wait times. This is a necessary tradeoff to provide the green time needed to coordinate the higher volume signals in the east/west direction.

The changes included implementing three different time of day coordination plans for both corridors. These coordination plans are used throughout the day depending on the traffic patterns.

  • Weekday Morning
  • Weekday Evening
  • Weekend

When the coordination plans are not in effect (i.e., 8:00pm to 6:00am weekdays) the traffic signals default to their normal “free” operation by managing traffic through solely actuation via sensors.

Ongoing Improvements

We are continuously monitoring, on a quarterly basis, the effectiveness of the timing plans and will be making minor adjustments based on observations. The Traffic Engineering Division is looking into designing new coordinated signal timing for the entire signal system throughout the City.


Travel time data was collected for both corridors before and after implementing the new timing plans. The results are summarized in the graphics below. In short, we saw an average decrease in travel times, number of stops and delay along the corridors.

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