About Traffic Signal Synchronization

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Project Overview

Traffic signal synchronization is a traffic engineering technique that coordinates green light timing across a series of intersections to allow the maximum number of vehicles to pass through, reducing stops and delays for motorists.

Stopping at multiple signals along an arterial roadway can be frustrating for drivers. As part of ongoing efforts to reduce congestion, the City of Elk Grove periodically updates traffic signal timing to improve synchronization along major corridors. The goal is to increase the likelihood that drivers will encounter green lights as they travel between intersections, reducing the number of stops and improving overall traffic flow. Drivers traveling near the posted speed limit have a higher probability of arriving at intersections during a green signal.

It is important to note that prioritizing coordination on major roadways may result in longer wait times for side streets and left-turn movements. This is a necessary tradeoff to provide sufficient green time for the higher-volume travel directions.

Previous Signal Synchronization Efforts

The City previously implemented synchronized signal timing in 2020 along Laguna Boulevard and Elk Grove Boulevard between Bruceville Road and Elk Grove Florin Road. In 2023, signal synchronization was extended west along Laguna Boulevard and Elk Grove Boulevard from Bruceville Road to Interstate 5 (I-5).

Current Project

The City recently completed its newest signal synchronization project, funded by Measure E. The project included eight major corridors and 110 traffic signals throughout the City.

Corridors included in the project:

  • Laguna Boulevard

  • Bond Road

  • Elk Grove Florin Road

  • Sheldon Road

  • Bruceville Road

  • Whitelock Avenue

  • Grant Line Road

  • Big Horn Boulevard

  • Elk Grove Boulevard

Franklin Boulevard was not included in this effort due to the ongoing Harvest Water Pipeline Project construction in the area but may be evaluated for signal coordination after construction activities are completed.

Project Results

Following implementation, all project corridors experienced measurable improvements in traffic flow. These improvements include:

  • Reduced average travel times

  • Increased average travel speeds

  • Fewer stops at traffic signals

  • Reduced delay at intersections

Signal Timing Plans

As part of the project, multiple time-of-day coordination plans were implemented to adjust signal timing based on changing traffic patterns throughout the day.

The following coordination plans are used:

  • Weekday Morning

  • Weekday Midday

  • Weekday Evening

  • Weekend

When coordination plans are not in effect (typically between 8:00 p.m. and 6:00 a.m. on weekdays), traffic signals return to normal free operation, meaning they respond to vehicle detection sensors and manage traffic based on real-time demand rather than coordinated progression along the corridor.

Ongoing Improvements

The City will continue monitoring signal performance on a quarterly basis to evaluate the effectiveness of the timing plans. Using signal performance data and field observations, staff will make minor adjustments as needed to further improve traffic flow and maintain efficient corridor operations.

Improving Mobility in Elk Grove

These improvements help create a more efficient transportation network for Elk Grove by reducing congestion, improving travel reliability, and supporting safer, smoother trips for residents, businesses, and visitors throughout the community.

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  • 🚦 110 Signals Coordinated
  • 🛣   8 Major Corridors
  • ⏱   Reduced Travel Time
  • 📊 Quarterly Performance Monitoring

Overall Project Benefits

  • 30% Increase in average speed 
  • 21% Decrease in travel time
  • 41% Decrease in number of stops
  • 46% Decrease in average signal delay

Frequently Asked Questions

What exactly does this mean?
  • Groups of signals are working together to allow drivers to get mostly green lights when traveling along a major street
  • By driving near the speed limit, signal lights are timed to turn green at the intersections ahead before you get there, or shortly after you arrive
  • This should save you time - and be less stressful as there is no need to speed up in order to make the next green
Why do I have to wait so long on the side street or left turn lanes when no one is coming?
  • In order to accommodate the signal synchronization, the total traffic signal cycle length must be increased, and the timings adjusted to favor the primary through movements
  • While this provides much needed congestion relief on the mainline, it can cause motorists on the side streets (secondary movement), or those turning left, to have to wait several seconds longer than before
  • This is the necessary tradeoff in order to provide the green time needed to synchronize the signals in the primary directions
  • Once drivers turn onto the major street, they should be able to make up the time they waited
How long should the wait be?

Typically the maximum wait time does not exceed 120-150 seconds, depending on the time of day and when you arrived at the signal.

What happens if an emergency vehicle goes by?
  • The signals are equipped with special devices to give emergency vehicles ( PD, Fire, and Ambulance ) priority at an intersection
  • The signal will change to green for the direction the emergency vehicle is traveling, and red for all other directions for their safety
  • This can cause the signals to fall out of synchronization and it may take several cycles for them to recover
Sometimes I get stopped on the major street and delayed a long time, and don't see an emergency vehicle; are there other reasons for this delay?
  • There can be several reasons for delays - pedestrians crossing, signal trying to get back in step with others in the group, or even a malfunction that holds the signal after the cars have all passed
  • Signal synchronization is not fail-safe, but in general the timing makes it more likely for drivers to receive a green light on the major thoroughfare
Can I speed up along the street and make all the lights?
  • The signal knows how long it takes to drive from the previous signal and won't change the lights to green until it is programmed to. The lights are programmed for drivers to travel at or near the speed limit. If you drive faster, you will arrive at the next signal too soon and the light will still be red.
  • By speeding up, you will stop more, so it's better if you drive with the flow near the speed limit for which the signals are timed
What are the benefits of synchronization - why are we doing this?
  • Signal synchronization is a low cost, very effective way to reduce congestion on a street and improve traffic flow, and avoid or delay much more costly widening projects
  • There are many other benefits from signal synchronization:
    • Reducing the number of times you have to stop at a signal
    • Saving you time in your trip across town
    • Making travel times more predictable
    • Reducing the amount of gas you use
    • Saving you money to use otherwise
    • Reducing vehicle emissions in Elk Grove
    • Improving air quality in Elk Grove
    • Reducing stress, frustration and aggressive driving
    • Improving safety and reducing accidents
    • Rewarding drivers for staying close to the speed limit
    • Reducing congestion and improving the flow
    • Reducing response times for emergency vehicles
Are all routes synchronized?
  • No. Currently there are eight streets with updated synchronized signal timing:
    • Laguna Boulevard / Bond Road 
    • Elk Grove Boulevard
    • Elk Grove Florin Road
    • Sheldon Road
    • Bruceville Road
    • Whitelock Avenue
    • Grant Line Road
    • Big Horn Boulevard
  • Franklin Boulevard is not part of this project due to the Harvest Water Pipeline Project construction in the area but will be coordinated after construction. 
When are the signals synchronized?
Currently, there are four different synchronization periods based on travel demands at specific times of day:
  • Weekday morning (6:00am to 10:00am)
  • Weekday midday (10:00am to 3:00pm)
  • Weekday evening (3:00pm to 8:00pm)
  • Weekend (10:00am to 3:00pm)
Does it matter what direction I am driving?

Generally, no, the lights are programmed to give the priority to both directions on the major street.

What happens at other times, late at night or weekends for example?

When the synchronization plans are not in effect (i.e., 8:00pm to 6:00am weekdays) the traffic signals default to their normal operation, with priority given to the primary direction and allocating green lights to secondary and left turns based on the vehicle detection sensors at each signal This will reduce the wait for secondary and left turn movements, but traffic traveling along the major street may stop more often.

Are there any enhancements to the signal system that the City is pursuing?

Yes. Reducing congestion is a major priority for the City. In April 2019, the City introduced theTraffic Congestion Management Plan (TCMP), which identifies the various strategies the City hopes to implement in order to reduce congestion.

In 2020, the City implemented a pilot project for the use of left turn flashing yellow arrows. Learn more about the flashing yellow arrow pilot project.

Who can I thank or call if I have questions?

You can call the City of Elk Grove Public Works Department at (916) 478-2256

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