How to Get a Greeen Light

Tired of waiting forever for a green light only to give up and blow through the intersection? Stop waiting and turn the light green!

Most modern traffic signals should be able to detect the presence of your bicycle and put you in the rotation to get a green light. This is important because many signals stay red until they detect a vehicle waiting to cross. While most signals can be tuned to detect bikes, it is often a matter of reporting it to the proper public works people and getting them to go out and do the work.

Loop Detectors

These are wires embedded in the pavement that are basically metal detectors. The most common types are the double loop pictured at the right, or a single loop.

For best detection at a double loop like this one, place your bike along the center wire. For a single loop, place the bike along the wire on either side of the loop.

If you have a posh carbon fiber bike with few metal parts, the detector might not work. You might need lean your wheel rims onto the detectors, or lay your bike down on the ground.

Video Detectors

Many newer traffic signals use a camera to detect the presence of vehicles at the intersection. It is usually mounted near the lights or at the top of the pole. Camera detectors are being used on most new lights that KCMO is installing on the “mast arms” that extend over the street. Many suburbs are also switching to video detectors, but MoDOT is sticking with loop detectors for state-owned roads.

For best placement put your bike in the middle of the travel lane even over to the far left.  One four lane roads you need to put yourself if the left-hand lane. Be sure your body is turned towards the camera, which might be at an angle instead of straight ahead. If that doesn’t work try jumping up and down and waving your arms. It sounds dorky, but it often works. Video detection often fails to detect bikes at night. Make sure you are wearing bright colors and have a good headlight.   Try waving the headline back and forth a bit.

If your city is using video detection they should also be using a silhouette device to test and calibrate the detectors. If you get the run-around, ask public works to do this. Or ask them to meet you at the signal with your bike for a live demonstration.

Sweet Spot Markings

Here are examples of markings and signage used to indicate the “sweet spot” where a traffic signal detector is tuned to detect a bicycle.  This marking can be used when loop detectors get paved over or when a video detector is pointed at specific spot. It’s part of the national standards for traffic control signage, so your public works department is allowed to use it without any extra permission or liability issues.


References

Detection of bicycles at demand-actuated traffic signals, humantransport.org.

Detecting bicycles and motor vehicles using the same loop detector, presentation to California Department of Transportation by Robert M. Shanteau, PhD, PE.

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