How do city traffic signals work?

Thanh -- June 11th, 2009

Last year, the City of Harrisonburg formed the Transportation Demand Management Program within the Department of Public Works. The program is comprised of a team dedicated to signal timing, signal coordination, and transportation planning. Earlier this year, the Transportation Demand Management Program released a set of webpages that details their program and provides insight into the complexity of traffic signal operation, timing & coordination, and maintenance.

Citizens can also use the links on the webpage to electronically submit traffic signal maintenance requests and sign maintenance requests.

For a fun, up close and personal opportunity to see this work (and the work of many other city departments), consider joining this year’s Citizen Academy, which begins September 3. Applications and additional details will be available in a month or so at this webpage.

6 Responses to “How do city traffic signals work?”

  1. Cindy says:

    What a perfectly timely article on the traffic lights for the first visit to your site! I sent in my suggestion and encourage others to also to make the Burg a more walker/biker friendly space. Nice job Thanh!

  2. Justin C says:

    If only the city had some way to tie all those traffic lights together for communication purposes. Some kind of “wireless” system. That would be useful.

  3. Thanh says:

    Justin, most of the signals in the city are tied together. From the web pages referenced above:

    “Many of the traffic signals along major corridors in the City communicate with each other through hard-wire connections or radio communications. These systems are tied in with a master controller that “talks” to multiple signalized intersections, allowing them to be coordinated with one another. For instance, the signals on Route 42 all the way from South Avenue to Gay Street are tied into a master controller that manages coordination for all of the signals when programmed to do so.”

    Read more at the bottom of this page, under “Coordination”, :)

  4. Don says:

    The info on those links is fantastic – great job folks. Now, is there a way to educate the motoring public in Harrisonburg that:

    “In order to be detected by the (video detection) camera, you must stop at the stop bar in the middle of the lane.”

    Whatsup with stopping 50 feet from the stop bar?

    And from “Signal Timing” section of Signal Function Primer:

    “The maximum time will keep counting down unless there is a ‘gap’, or space in traffic. Typically, the gap time is set at 3 seconds, meaning that the signal will change if no vehicles are detected for 3 seconds.”

    So folks, how about disconnecting that cell phone call and MOVING when that green arrow lights up – it’s the neighborly thing to do.

  5. Karl says:

    I’m convinced that the lights talk to each other…when they’re not saying “stop that blue car” they’re saying “let’s screw with this guy.”

  6. mikekeane says:

    I haven’t checked out these websites yet but i’ve been fuming lately that my wait time driving from reservoir to court square on 33 is completely unacceptable. In addition the sterling/market light will skip the north side of the street, so will the 33/mason light. I’ve been skipped 3 times in a row at the light all the way down on south main/covenant. I know i should walk more but its not always the best option. I can’t think of a worse city/town than Harrisonburg for inconsistent traffic lights.

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