Longtime California cyclist advocate Bob Shanteau sent this 1985 report on traffic signal bicycle detection and asked me to archive it here at Cyclelicious.
Everybody who cycles on American roads has likely encountered problems triggering a green light at intersections. This report looks at solutions used in other cities, including the now-familiar bicycle pavement stencil that was apparently pioneered in Boulder, Colorado and San Luis Obispo, CA. This stencil helps cyclists identify the placement of their tires over the detection loop embedded in the roadway.
The report discusses the problem (cyclists can’t get across many San Diego intersections) and proposes solutions, including technical discussion on inductive loop placement, sensitivity settings, and training for the signal technicians who maintain traffic lights. The report’s discussion on “beg buttons” notes their shortcomings for cyclists, recommending their use as supplements rather than replacements for in-pavement detection methods that require no interaction by the cyclist.
Some fun quotables from this document highlight both how far we’ve come with cycling and cyclist advocacy in California, and how far we have to go.
- “Changes in the traffic signal systems to enhance their usefulness by bicycles should not be made at the expense of the majority of road users.”
- “The cost of pedestrian push buttons is very low and no additional controller equipment is required. Theoretically speaking, if a pedestrian can be trained to push the button, then a bicyclist, with apparently more skill by virtue of the fact that he/she hasn’t fallen down, can also. The obvious flaw to this theory is that too many pedestrians don’t bother to push the button before crossing the street and bicyclists’ behavior can probably be expected to be similar.”
- “Local bicyclists suggested … add some device” [e.g. a transponder of some kind] “to the bicycle to make it easier to detect at traffic signals.” [For whatever it's worth, I continue to hear similar suggestions today.]
- Regarding early experiments with pavement stencils to aid in positioning on detector loops: “A review of time lapse films, taken before and after, shows no evidence that the bicyclists understood the purpose of the markings.”
Today, all new actuated traffic signal installations in California are required to detect bicycles thanks to AB 1581. California law also mandates green light timing that gives cyclists enough time to cross intersections for new traffic signal installations.
You can download and read the full 48 page report as a scanned PDF here.