With gas prices the way the are, I have been doing a lot of motorcycling lately and today I came across something that engenders this thread. The bike was not heavy enough to activiate the stoplight facing me to turn green.
What are my legal alternatives? Wait until somebody comes along with sufficient weight to activate it? Go over to the right lane turn right go down a block find a parking lot and turn around and head the direction I wanted to go? Turn around and try to find a street without a weight activated light? The proverbial hell freezing over scenario? Or are there legal grounds for me to cross on red? (and no there was no pedesterian button that I could get off the bike go over to the button and press).
Are you sure they are weight activated? I thought there were activated by electric fields and the motorcycle should have enough metal to set it off. I’ve been told to drive them along the saw lines in the roads where the induction (?) wires are buried.
And here is a description of the most common type of detector.
“Because the sensor is a metal detector, a vehicle’s weight doesn’t really affect it. It reacts to only the presence of metal (or an electromagnetic field). Most of these loop sensors merely serve as an antenna [in what is] known as a whe[a]tstone bridge. When a certain mass of iron interferes with the balance of the circuit, the circuit reacts. If the electrical value of the antenna/bridge changes in any way, the voltage will be changed, triggering a relay to switch the lights. These sensors detect large masses of metal, and a touring bike surely qualifies. A sensor may be out of adjustment, however.”
The author made a couple of booboo’s, like not capitalizing Wheatstone and misspelling it, that might cast a little doubt on his accuracy. However, his description agrees with what I have learned about how such devices work.
I had this same problem with bicycles, which in Texas are supposed to operate like other road vehicles and are expected to stop at the lights, etc. It’s pretty annoying when you’re trying to obey the law but the technology is working against you.
Whatever the type and remember this is rural America so these new-fangled E-lecktronic dodads may not have gotten here yet (there could be a little guy up in the light shinning a flashlight for all I know) - it still didn’t work until a woman drove up behind me and activated it. If someone could further enlightenment me on what my alternatives are next time it doesn’t work I would appreciate it (and I will stasrt packing a sandwich, Cliffy)
You can get magnetized plates to bolt on motorcycles that are supposed to help. Don’t know if they really do or where to get one though.
I know that some places (sorry, no specifics again) allow motorcyclists to run red lights in such situations after waiting a decent amount of time.
I imagine a local motorcycle shop or group would be able to help in either regard.
I ride almost daily and when I come up to one of these lights that doesn’t change I do one of two things. If there’s a car behind me, I’ll roll forward enough for the car to creep up onto the edge of the sensor and that’s usually enough to trip it. If there’s nobody behind me, I’ll just go when the coast is clear after waiting what I believe to be a reasonable amount of time. I’m not going to sit there until I get hit by somebody who didn’t see me. I haven’t gotten a ticket for that yet but if I did, I think I could justify it if I had to.
(BTW, I find it sometimes helps if you stop the bike right on one of the sensor lines.)
You can get those from most anyplace that sells motorcycle accessories. From the reviews I’ve read, they don’t really help very much, though I’ve never tried one myself.
What about a motorcycle with an aluminum engine? Although the frame and other parts may be steel, an aluminum engine would leave a large metaphorical hole in the induced magnetic field of the bike. Aluminum isn’t a soft magnetic material (easily magnetized and demagnetized) and so would be relatively unaffected by the magnetic field of the current.
BTW, the scientific term for this is magnetic flux. Magnetic flux is a change in a magnetic field, and changes in a magnetic field induces a current through a circuit. The iron in a car is magnetized by the magnetic field of the current flowing underneath it. The car’s presence (and movement) creates magnetic flux and therefore a change in current in the circuit below. As described, this change in current trips the stoplight program to give you a green light.
If the sensors work like a metal detector, I don’t think it’s necessary for the metal to be magnetic. After all, guys with metal detectors find non-ferrous items all the time (like lead musket balls, for example). My bike has an aluminum frame and it seems to set off the majority of signals just fine.
The outline of the sensors at these stoplights can be seen in the pavement, usually as a what looks like a rectangular shape cut in the asphalt. The trick to setting these sensors off with a bicycle is to position the bike over one side of the cutout. Roll your wheels right over the line in the pavement. This seems to be the most sensitive part of the sensor.
If the intersection is new, the wires may have been laid down before the asphalt was poured, in which case there wouldn’t be any telltale lines.
And the detectors don’t detect magnetic materials per se (although a large magnet probably would show some sort of signature), but conductive materials. Since aluminum is a better conductor than iron, it should, if anything, be even more easily detected. Both theory and annecdotal evidence indicates that laying a bicycle flat on its side will make it more detectable; I’ve never gotten this to work, but that may just be because I was in the wrong place (the intersection I tried it at was one of those new construction ones without grooves).
Since what the sensor detects is <i>change</i> in the circuit, if you haven’t set it off when you first show up, you’ve made your modifications to the EM field influencing the circuit already and sitting there like a bump on a log isn’t going to introduce any further change. Otherwise it’s just going to keep comparing the circuit state with you sitting there… to the circuit state with you sitting there… and say to itself “No Change! No One Waiting!”
Move the big hunk of metal around to introduce further changes. I’ve had to do this with my <i>car</i> at a particular light near where I used to live in Nashville.
The shop I work at carries them, they’re called Green Light Triggers. Never used one personally, though. If I’ve waited through a full cycle of the stoplight and still haven’t got my green light, I run it if no traffic is coming. I know I probably would get a ticket if caught, though.
Our newspaper has one of those “local help” columns, and they have addressed this sort of issue. If it is an intersection that you encounter a lot, you may be able to ask the city to re-calibrate it, so your motorcycle will trip the sensor.