that's why I only wait 15 seconds, Al.

Do you mean you only wait 15s because all the light triggers in Seattle respond within 15s or do you mean you only wait 15s because more time is too long to wait and you'd rather break the law?

Al

Get off the bike, and lay it down- in the street?? No offense but that's some pretty weird stuff. Esp if it's snowing or raining and you're carrying any kind of a load on the back of the bike

There's gotta be a better way.

because I'm not going to wait two minutes, that indicates a faulty sensor to me. I wait fifteen seconds, then start looking for an opening. On some regular, obviously busy intersections, I just wait.

I'm always available to take tickets for my cycling transgressions, i rarely try to outrun the police on my bike

HH is probably right on this one...he even mentions Forrester

As long as you agree that technicaly not giving the time or conditions for a light to change does not make it a faulty sensor, but in that case why 15s, why not just run it immediately? It seems by your last sentence that you take full responsibility for any laws you break.

Al

Sure, Al.

On a lot of the lights around town, I know they will pick me up and cycle thru the light in due time. I wait. At unfamiliar intersections, when I see no traffic behind me, or opposite me, to trigger the sensor, and I personally feel my parking my bike over the sensor does not trigger the light cycle (m/l 15 secs?) I decide if I will try to progress once I can clear the intersection safely. And sometimes I don't.

Sometimes, there's very little cross traffic, while a sole bicyclist stands at the intersection of a minor street and an arterial, waiting endlessly for the signal to change. Screw that.

I don't even think my approach is legal in WA.

It is one (but a minor one) of the reasons I avoid minor streets vs. aterials, they are so much slower with many stop signs and traffic lights that take forever to cross arterials. Even if I wanted to break the law and run a red light across an arterial during 6am-11pm hours, I couldn't safely as arterial traffic density and speed is high enough that there are so rarely gaps in traffic long enough to cross 7-lanes of traffic. In the summer waiting at a minor street to cross an arterial can be brutal to wait 2min in 117F with no movement induced breeze.

What is even worse is crossing an arterial without a traffic control. Several years ago I used to ride the bike paths on canals and they don't have a light to cross. I once waited for >6min looking for a gap and gave up and rode up the sidewalk 1/4mi the wrong way to the nearest traffic light to cross. I stopped doing this as I hated wroing way sidewalk riding.

Al

An idea I've posted before in similar threads is that it would be a nice feature to have an LED illuminate on each of the corner signal support posts that indicate when a sensor has been triggered. That way at least cyclist (and motorists and peds after button is pushed) know that the signal has been triggered and now they just must wait.

Al

There are some new walk signs in my neighborhoods with countdown LED and/or an audible countdown. I have no idea what these do, since they don't seem to be coordinated with the lights (I didn't hang around to check them out).

You have certainly got some good - and bad- information on this one. Since no one else has addressed your question based on you picture, I'll give it a shot. Tripping the light is more a matter of location of the bike than any other factor. You want to position your bike over the most sensitive part of the loop (motorcyclist make this mistake, too.) Once you know where to find that place, most lights become easy to trip.

To understand the physics of the induction loop, you have to think of what's going on. The wire in the ground is only the physical manifestation of the induction loop. Unseen to us, since we don't see in magnetic fields, is another loop of magnetic lines extending out from the wire for a few inches to a couple of feet. The magnetic lines have strengths that are dependent upon their distance from the wire. The closer to the wire you are, the stronger the field strength. (All wires actually do this. You can get current detectors that clamp around the wire and allow you to measure the strength of the field as well as various other properties of the power within the wire.) This goes all around the wire from the signal box, out to the street and back to the signal box.

Now think of you and your bike coming along and going through this magnetic field. (Sorry but I can't draw worth beans so we'll have to make do with words.) Looking at your picture, if you cross over the magnetic field in the middle of the circles, you only break the field in 4 places and for pretty short duration. Most of the current sensors for these loops are set pretty low since they only have to detect cars directly over them. Cars have great masses of conductive materials in them so they detectors don't have to be set too sensitive.

But look at your picture again. There is a wire going from the detector box to the loop in the pavement. But what you forget is that this has to be a curciut, so there has to be a wire going back to the box. Usually, but not always, the wire going out and the wire coming back are in the same groove. (You only have to cut one slot that way.) Because of the magic of electric fields, the magnetic field of this 2 wire system is going to be twice as strong as those in the circles from your picture. If you ride with your wheel directly over this line (to the right of the circles), you will trip the sensor! Presto! Chango!


The loop that you are trying to trip is one of several different designs. Some are better for bikes than others. The 'figure 8' loop is probably the best since the most sensitive part of the loop is the easiest to find. The double circle one is probably easy to trip but it will put you in a bad lane position. I've seen them on the 'net but I have yet to run across one in the wild.

OK Looks like I'll try this over the next couple of days. It won't work for the left lane turn (other picture) but let's see if we can at least get one or 2 to change.

For the left lane (I'm assuming that it's another intersection) turn, there is probably a loop that is buried under the pavement (if it isn't obvious). I am a bit confused however. Is the white X marked on the pavement? If it is try lining up on the white X for a car length and riding in a straight line towards it. The loop extends quite a ways back from the intersection. If you line up directly over the wire, your wheels should trip it. The issue, as others have said, is finding that wire.

For the left lane (I'm assuming that it's another intersection) turn, there is probably a loop that is buried under the pavement (if it isn't obvious). I am a bit confused however. Is the white X marked on the pavement? If it is try lining up on the white X for a car length and riding in a straight line towards it. The loop extends quite a ways back from the intersection. If you line up directly over the wire, your wheels should trip it. The issue, as others have said, is finding that wire.