I’m continuing with the topic of detecting bicycles at demand-actuated traffic signals.  You’ll recall that the City rep with whom I was corresponding suggested the metallic composition of the bicycle matters.  I was thinking that as well, but had in mind the composition of the frame, and always thought steel would be the easiest to detect.  I wonder if that’s what the City rep had in mind.  Then I read this.  Turns out the bicycle’s rims matter more than the frame.  Makes sense as the rims are nearest to the sensors.  Also turns out that aluminum rims are easier to detect than steel.  Would have guessed the opposite.  The design of the sensing loops matters as much as anything.  We should insist on “diagonal quadrupole loops” which were developed for better detection of narrow vehicles (i.e. bicycles and motorcycles).  We also want detectors with an inductance change sensitivity level that goes down to 0.0025% to reliably detect bicycles.  If the City cares about it’s pledge to provide complete streets, they would do well to read this article.  I’ve posted a link on See Click Fix.  Wish me us luck!


2 responses to “More

  1. If carbon rims become common, inductance loops will become less useful. The long term goal should be some sort of passive detection, like video or ultrasonic sonar. These could also replace beg buttons for crosswalks.

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