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Traffic Signal Synchronization

2020 Green Wave Update

Traffic signal changes have reduced congestion and travel times along major east-west thoroughfares.

Learn more about the 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 plans to implement updated traffic signal timing plans 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.

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 only two streets with updated synchronized signal timing:
    • Laguna Blvd/Bond Road between Bruceville Road and Elk Grove-Florin Road
    • Elk Grove Blvd. between Bruceville Road and Elk Grove-Florin Road
  • Next year we are planning to complete the synchronization on Elk Grove Blvd and Laguna Blvd between Interstate 5 and Bruceville Road
  • In the future we hope to continue to add synchronized corridors based on traffic demands
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 the Traffic Congestion Management Plan (TCMP), which identifies the various strategies the City hopes to implement in order to reduce congestion.

In 2020, the City will be implementing 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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