By ROBERT JOHNSON
Monday, February 1, 2010
Although bicycling on roads has always been legal, some infrastructure is designed only for the automobile. When a bicyclist encounters these features it can be frustrating for all road users. Bicyclists get annoyed because they have encountered something that does not work well for them, and motorists are confused watching bicyclists react to something in a way the motorist does not understand. One of these pieces of infrastructure is the device that communicates to traffic lights that a vehicle is waiting to cross.
There are three main types of traffic light control mechanisms. Some lights operate on a timer, where the signal changes periodically regardless of traffic conditions. There also are lights that use a camera that senses when a vehicle is waiting, even a bicycle. The type bicyclists get most frustrated with, however, are the ones that use an inductive loop buried under the pavement that senses when something metal is on top of it. As you can imagine, this type of system often has a hard time picking up something as small as a bicycle and changing the light accordingly.
Inductive loops can be adjusted to different levels of sensitivity, but it is a difficult balancing act. They need to be sensitive enough to detect a vehicle in that lane but not so sensitive that they pick up a vehicle in the lane next to it. Now imagine how difficult it can be to adjust them to pick up a bicycle, with maybe 20 pounds of metal, and not mistakenly detect a 3,500-pound motor vehicle just a few feet away in the other lane.
In most communities, because bicycling might not be as popular, it can be safely assumed that the person who adjusted the magnetic induction loop was not doing so with bicycles in mind. This means a bicyclist can sit and wait at a red light without much hope that the light will change. Columbia used to be a community like that. I can remember waiting at red lights for a long time before eventually having to get off my bicycle to walk back and ask the motorist behind me to pull up so the light would change for us. Luckily for both motorists and bicyclists, this has mostly changed.
In the past couple of years most of Columbia’s intersections have been adjusted to pick up bicycles that are properly positioned. To be recognized by these systems, bicyclists need to arrive at a red light in the middle of the traffic lane and look for the lines in the pavement where the cable is buried underneath. These cables are often buried in a double-loop configuration. The bicyclists should position their front wheel in the middle of this “∞” where two of the cables come together because that is the most sensitive position.
There still are times when the induction loops simply will not work for a variety of reasons. Perhaps the bicycle is made of carbon fiber and not metal, or the light just has not been adjusted properly. This is why there is a new state law that went into effect on Aug. 28, 2009, nicknamed “Dead Red.” This law allows someone riding a motorcycle or bicycle to proceed through a red light if it is malfunctioning. Cyclists have to first stop and give the light a chance to work, but if it’s obviously not picking them up, they can proceed through if it is safe.
Adjusting inductive loops to pick up bicycles has not only made bicycling more convenient but safer. Today, it’s pretty rare to come across a signal in Columbia that will not pick up a properly positioned bicycle, and that makes the city more inviting and safer for nonmotorized travel.
For more information go to: www.pednet.org/active-living/traffic-lights.asp.
Robert Johnson is education coordinator with the PedNet Coalition. Reach him at (573) 289-6479 or firstname.lastname@example.org.