starla

There's a new traffic on the route I take to my mom's house. I was happy the light was installed because that intersection is a bear to try and cross. So I waited there for about 2-3 minutes for the light to change, looked all over the ground for a rectangle, circle, or diamond shape that I could use to trigger the light, but could not find one. I was about to just run the light when a car pulled up behind me and triggered a change. I was told that the sensor might be underground. If so, is there a way for me to trip this? Waiting for a car could take a while because the road I was on is lightly trafficked, but the cross road is a 55mph four lane road that carries a lot of traffic. An adequate break can take a while.

BarracksSi

This thread just got pushed back to Page 2:

https://www.bikeforums.net/commuting/437590-tired-red-lights.html

If cars come often enough to trip it, I'd say to wait to the side, enough to give them room to move over it. If cars are rare, maybe stick a magnet to your frame, or lay it down sideways, etc. It could also be a motion sensing light; don't know how to trip those.

ItsJustMe

You can ask the city (or whatever) to mark where the sensor is and confirm that a bicycle can trigger it. They're supposedly required to be trippable by any legal vehicle.

I don't believe that magnets do anything; unless they're moving they won't be any different than a piece of iron the same size. The inverse square law applies though, so your rims 1" from the pavement will be many times more effective than your frame 12" from the pavement (144 times more effective, in fact). If you can figure out where the loop is, or better yet have the city paint where it is, and you get your rim right on the loop, it'll probably trip.

making

I ride over one every morning, and have still not gotten it to trip unless a car comes along. The light will eventually cycle throurgh green but not the turn arrow without a car. This AM I rode directly on it and stopped. nuthin.

tate65

3 things
1 Ride down the line where its burried, you can usually see the cut in thestreet
2 I have a strong magnet I epoxed in the heal of my cycling shoe, when I stop I place it on the cut
3 If you can't get it to trip, call the city streets department, ask for a report number and a time frame when you can expect them fix it.

Heckboy

Pulling up directly over the detection loop and laying my bike over to the side has been effective in some cases.

Later,
HB

Booger1

You could try a tin foil suit,hot during the summertime.Wrap the bike in tin foil.Wear tin foil booties.Or when all else fails,you could push the crosswalk button?

making

I already tried that, nuthin.

CastIron

Magnets? Foil? My quarter ton motorcycle won't trip half these things. If it won't change for you then it's faulty. Yield to all and proceed when safe. It's your only practical option.

Booger1

The crosswalk button doesn't work? or doesn't work fast enough?Tell the city if it doesn't work.

starla

Dude, you made your point. If there was a crosswalk button, I would use it.

making

I was talking about the tin foil suit. I never ride on the sidewalk. Last time I admitted to that I got in trouble.

ToddDav

Those sensors usually work via induction. This means that the ferrous metal in a car gets enough reaction to send a little charge to let the light know that it is supposed to turn. Aluminum will not do the trick, so laying down your bike might yield poor results depending on what it is made of. Also, scooters and motorcycles sometimes have trouble tripping them so a bike is prob not going to do the trick most times.

You need a rare earth magnet, the kind you find in a hard drive or somewhere like here. This is something that will hold a claw hammer to a metal surface with relative ease. A refrigerator magnet is nt going to cut it.

Also, rare earth magnets tend to rust when exposed to the elements, so wrap it in a plastic baggie and slap it to something magnetic, like the bottom bracket of a steel bike. If you bike is Aluminum, you will have to find another way to affix it since aluminum in non-magnetic.

ItsJustMe

I was going to suggest that, but the OP indicates that this is a difficult intersection if you don't have the light.

For other posters: crosswalk buttons are not that common around here and the OP has indicated that there isn't one on this light. Is it a given you'd get a left turn light with a crosswalk button anyway? And how do you ride over to the sidewalk, push the crosswalk button, then get all the way back over to the left turn lane? Seems really awkward and possibly dangerous.

Cerberusgl

My work has security gates with loop sensors and I never had problems with them opening for my commute bike but when I came to work on my Carbon fiber bike it didn't open so I jumped off and swung my bike horizontal to the ground and just a few inches off the ground and that was enough moving metal to trigger the gate although it might have looked a little funny.

Another intersection that is an exit for the bike path and access to a boat ramp the sensor only works if you go over it quickly but the sensor is right up to the intersection so I have to brake hard to trigger it and still stop before shooting into the intersection. At night the gate is closed so you have to go around the gate line up with the sensor and give a good push-off with one pedal stroke and then hit the brakes.

What ever it takes.

ItsJustMe

This is incorrect. Induction loops work with anything conductive. Someone says this EVERY TIME there's a question about this.

The induction loop is a big metal detector. Do you think metal detectors only pick up iron? They pick up zinc, gold, silver, aluminum, anything.

Any conductive OR ferrous material in the loop will be picked up by the coil.

I have an aluminum bike with aluminum rims, fork and handlebars; The only steel on my bike is the spokes (stainless, almost no reaction to magnets) random screws, the saddle rail and the drivetrain, but around here the *properly* adjusted sensors pick it up no problem.

Cerberusgl

Although aluminum isn't magnetic induction works with any metal. In a physics class I took we had a u-shaped electro magnet and a plate of aluminum. If you slide the plate in between the magnet heads slowly there was no resistance but if you tried to move it quickly there was a lot of resistance. So aluminum can trip an inductive sensor, just maybe not as easily.

michaelalanjone

I don't see how it could be triggered by a magnet, unless there was a magnetic reed switch, activated by a movable slab that had a magnet attached to it, or some sort of magnetic field sensor. Both are doubtful.

The switches (at least around here) are usually triggered by weight. My old motorcycle didn't set some of them off (it was a light bike, at 550 lbs + my weight, 175 lbs = 725 lbs).

Options:

1. Ride a Huffy Roadmaster.
2. Eat at McDonald's every day for a month.
3. Stop, and if the light doesn't change, run it.

I always opt for #3.

starla

I emailed the city and was told this was a temporary light until they install a new one some time in 2009.

I am a little confused by the response so I asked him if he was telling me that it was okay for me to run the red if there was an adequate gap in traffic, or if I was stuck waiting for a car to trigger the light.

To clarify the intersection because he refers to the MUP, which I am not using and does not impact my dilemma:

making

I have not given up on the aluminum foil yet.

BarracksSi

Ah, I knew something was up. After all, you yourself said that you couldn't see any loops in the pavement.

michaelalanjone

Hey, I found this wiki on traffic lights:
https://en.wikipedia.org/wiki/Traffic_light

This page has a photo, that shows the insides of a traffic computer box (near every intersection with lights).

Hmmm - I guess that disproves my theory that there is a chimpanzee inside that box, controlling the lights.

michaelalanjone

That must be it! Monkees control the stoplights!

ItsJustMe

The induction loop is run with alternating current, so the field moves which means the metal doesn't have to. The metal in the presence of the alternating field presents a resistance to the field fluctuations, which causes the frequency in the oscillator to drop. It works with any conductor because the magnetic field causes a current to flow in the conductor, and the current flow in turn generates its own magnetic field.

You can pick up aluminum with an electromagnet if the field is fluctuating at the right frequency.

HardyWeinberg

There is only one sensor here that reliably works for my bike, and it is on a barely used street where right-on-red is never a problem anyway. I have one brutal intersection where the sensor doesn't work, the button doesn't work, and a car coming toward me (they never come from behind me at this place) triggers their light but not mine.