This blog post was originally going to be about my frustration with and the danger of traffic signals that operate on sensors.  It is very annoying when trying to obey traffic laws, you are ignored by traffic signals.  In times when traffic is light or non-existent, you will have to run the light because it will never change for you.  This is a very dangerous scenario!  We all know, there is an inherent danger to running red lights in motor vehicles.  At least in that case, the vehicle is easy to see.  Run that same light on a bicycle, and your chances of being seen decrease dramatically.

This brings me to the second part of my post - the “A Day Late and a Dollar Short” part.  As I was riding around town on Black Friday, I got caught by a traffic light that wouldn’t change for me.  There were no cars and no crosswalk button that I could push to encourage the light to change to green.  My choices were to wait a very long time for a car to meander down this secluded side street,  turn around and abandon my trip, or attempt to run this red light with as much precaution and safety as you can get when breaking the law.  This made me realize that though bicyclist have as much right to the road as motorized vehicles, the roads were not designed with bicyclists in mind.

First I started researching how traffic lights that change based on vehicle presence worked.  I found that there are three basic types:  Ones that use lasers, ones that use air hoses, and ones that use inductance.  If you’ve seen the “pressure plates” at stop lights that look like your vehicle tire must be on them to work, then you’ve actually seen the inductive loop sensors.  Those pressure plate looking things are not actually pressure sensors, but are cuts in the asphalt to insert a coil of wire used in inductive loops.  I am not going to butcher the explanation, because I barely understand it myself.  There is a good explanation of it here.  Let’s just say that inductive loops provide a electromagnetic field which is interrupted by large metal objects (cars, trucks, etc.).  Bikes do not have enough inductive material to interrupt that electromagnetic field.  During my research, I found several products that were created for bicyclist to solve this problem.

GreenLight has two products (one an improvement over the other) that promises bikes will “Stop Getting Stuck at Red Lights!”  Here is their explanation of how their product works, but the abbreviated version is they have small metal magnet that  you place on your bike that will interfere with the electromagnetic field at intersections, “fooling” the computer into thinking your bike is a large metal object, thus triggering the light to turn green.  At $24.95 with an unconditional 30-day money back guarantee, it is probably worth a try.

If you are not wanting to buy a product, Instructables.com has a DIY version that involves epoxying a magnet to the bottom of your bike shoe.  Comments to the blog post indicate it works and suggest other alternatives.

Personally, I don’t run into this problem very often in Atlanta.  I happened upon it Friday, because I was biking around town in Columbus, GA.  If you are running into this problem often, try one of these solutions and let us know how it went.

And there you have it.

- Joe.

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