Seattlest Pix 09Nov07
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Seattlest Pix 09Nov08
We're stumped by those weight-activated turn arrows at intersections. When you're on a bike, what do you do? If you're at the head of the line, you don't have a car in front to trigger it and you're there forever. (And sometimes drivers politely avoid crowding you, and don't trigger the plate behind you.)
We're baffled. Sometimes we bike through the crosswalk instead. Sometimes we just turn a street early to avoid the light. Is there a trick to this we don't know about?
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It's not weight. It's an electromagnetic coil (that's why they are loops).
Your massive ferrous car is enough to trigger it.
Your aluminum/composite/etc bike is usually not.
There is a trick. Stick some magnets in your shoes.
http://www.instructables.com/id/Traffic-Light-Trigger-for-your-Bike/
I should add that I know this because I was a parking booth attendant in college, and for kicks, we used to wave manhole covers over the coils to screw up the car counts.
Our supervisor: "The computer says 300 cars came in today, but 400 cars left. Are they multiplying in there or what?!?!"
Y'all are geniuses. Plus, you've prevented me from trying out what happens if I jump up and down on the plates. I'll just magneto myself up and see what happens.
Wow. I was going to come in with some smart ass remark like "Hit the walk button," but my smart ass is wow'd by smart science.
Science is way cooler.
The PI addresses this issue in its "Getting There" column from time to time...
http://seattlepi.nwsource.com/transportation/278614_getthere24.html
Not very helpful, but the columns about the same problem happening for motorcycle riders has the same info as above. The advice is always to try and ride the motorcycle over the edge of the ring, not through the center.
If you're on an aluminum or carbon frame though, not sure how that would work. Maybe note the intersection where the problem occurs and call the City DOT?
I did find this page on "How to Turn Signals Green" but it requires you to experiment a bit, which the cars missing light cycles behind you don't seem to appreciate.
There's a dude who rides a UNICYCLE to work, I see him during my daily commute and it boggles my Ford Taurus-driving mind--not least because I'm trying to figure out how he navigates intersections!! He has to stop half a block away sometimes, wherever there's a telephone pole to lean against. Crazy.
Short-term fix: Exactly where you ride makes a difference. Some intersections have the "sweet spot" marked with a little "T" or a stencil of a bike - if you see that, roll over it, and the chances are you'll actually trip the sensor. If you don't see one of those, look for the marks in the asphalt where it's been cut to put the induction loop in - the more you can ride over the edge of that, the better your chance of tripping the signal. If even that doesn't work, laying your bike down momentarily will usually do the trick, though for safety reasons I'd only recommend this if you can see a long way behind and know no cars are coming - otherwise it's really a better idea to press the button for the pedestrian signal, or just run the damn light.
Longer-term fix: all of that said, Seattle has a number of intersections where the detector is just not sensitive enough. I know of three on my 6-mile commute. These are faulty. When you think you've found one, email walkandbike@seattle.gov to ask them to fix it. Don't expect the courtesy of an answer, or a quick response--this department really sucks at customer service--but it's still worth emailing them in the hope that when they get enough complaints they actually do something about it.
And finally a legal question: I will run a red light if it's failing to actuate for me, on the basis that it's a faulty signal, and we're supposed to treat faulty signals like stop signs. If a police officer saw me doing this, would they see it the same way?
Re: red-light running
Dude, they ticket jaywalkers in this town... Need I say more?
Well, most sensored lights have pedestrian buttons, which is what I use on my route. It is legal to ride a bike in the crosswalk and drivers must treat you as a ped. In cases where there is no ped button, I treat it as a four-way stop and cross carefully. While I suppose it's techincally illegal I think a cop would have a hard time arguing that you had another choice.
p.s. -- Thanks for wanting to ride responsibly.