Triggering Traffic Signals

Triggering “demand” traffic signals by bicycles has been has been a problem for time immemorial… However it looks as though newer technology is creating the opportunity for more effective sensing. In general the best chance you have of triggering a demand signal is to pull up to the stop line in the center of the lane.

We’ve all been there — a traffic light that won’t change.

For what to do about the immediate problem, ADOT’s Arizona Bicycling Street Smarts recommends waiting, or failing that, treating the signal as inoperative:

…If your bicycle doesn’t trip the detector, you have to wait for a car to do it, or stop and wait until it is safe to go through the red light. Going through the red isn’t against the law, because the light is inoperative (Arizona Revised Statutes 28-645).
— retrieved from Chapter 9, When Traffic Lights Don’t Turn

But in the longer view, it’s important to get the situation remedied so that you and all bicyclists can avoid having the problem. The most common type of detector is still the inductive loop — such loops can readily be adjusted to detect bicycles (even alloy ones; the exception is carbon-fiber *wheels* are not possible to detect with the loop). And cites are transitioning to more and more use video detection; which can also be adjusted.

video detector;

The trick is to report and follow up with the jurisdiction who controls the signals. I recently had very pleasant experiences with both the City of Chandler (special thanks to Mike Mah), and the City of Tempe (special thanks to Christine Warren); by submitting requests to their streets departments. In both cases the results were prompt; and city personnel followed up with me to make sure the problem was corrected.
Brandon Forrey informed us that the City of Peoria now uses video at all new installations.

Below is a sample of how to contact a few cites — most cities have something similar… Please share your experiences.

City of Chandler:  Contact Chandler Form at,  Please choose Streets & Transportation as the category. Or by phone: for Traffic issues, such as bike lanes, striping, signing, traffic signals and street lights, you can call (480) 782-3454. For Streets issues, such as pavement condition, sidewalks, street sweeping, wheelchair ramps, etc, you can call (480) 782-3499.

City of (click “submit request”) or smartphone app (android/ios) or call 480-350-4311 for non-emergency requests for service or information, Monday-Friday, 7 a.m. to 5 p.m.

City of Phoenix: or Problems also can be reported to Street Maintenance Division staff during normal business hours at (602) 262-6441

2 Responses to “Triggering Traffic Signals”
  1. azbikelaw says:

    cool video about UDOT (utah)’s use of radar to detect any sort of vehicle and can allow, e.g. more time to a bicycle…

  2. admin says:

    “In 2007, California enacted a law to require all new and upgraded traffic signal sensors to detect bicycles and motorcycles. This was implemented in 2009 when Section 4D.105 of the 2010 California Manual on Uniform Traffic Control Devices was revised to define California’s performance standard for bicycle detection. As a result, demand-actuated traffic signals in California are now routinely designed and adjusted to detect bicycles. The most common implementation of a sensor meeting the CA standard is a type “D” quadrupole loop, although other loop shapes and video are used as well. Video based detectors in California are adjusted to detect a bicyclist using a headlamp at night…. BikeWalk NC recommends that North Carolina adopt an equivalent standard to California’s…”

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