Red-light techniques for the urban cyclist, Part 2: Loopy

EUGENE BICYCLIST: Hey, we’re back for Part 2 of our red-light Q&A. Our questioner, I see, is still holding that track stand.

QUESTIONER: Yeah, but man I’m glad you’re back.


I really have to pee.

Oh, go ahead.

(Questioner leaves and then returns) That’s better. So continuing our Q&A, I was wondering: Did you have a bad-karma experience yesterday?

I did. The thing is, it’s the perfect anecdote to get started talking about what I want to talk about today: inductive loop sensors. Would you like to know about inductive loop sensors?

I thought I got to ask the questions.

I was just using my “media training.”

What’s media training?

That’s when a consultant comes in and — for utterly exorbitant sums of money — tells people who work in government or business how to talk to a reporter — or as they like to put it, how to “interact with the media.”

Really? What do they teach in media training?

One of the important things is: It matters not one iota what question the reporter asks. When you answer, you simply talk about whatever it is you want to talk about.

That explains a lot of the interviews I have watched on the TV news.


So, I was wondering if you know anything about how it’s going on that new stretch of bike path they’re building out in the River Road area?

Oh, I’m so glad you asked about inductive loop sensors! These are just terrific if you have to wait for a red light.

But I asked about …

Here is an example of an inductive loop sensor. We saw this in the previous post, remember?

Yeah, but that wasn’t my question.

Do you mind? I rarely get to dispense actual useful information here. Look: Say you are approaching a red light and there in the bike lane is an inductive loop sensor. Do you know what to do?

Ride straight through the red light?

No, no! You park your bike over it like this:

Another blurry photo? Seriously?

You see, the inductive loop sensor will sense that there is cyclist waiting for the red light. And it sets the light to change to green. In theory.

Do we know for certain that these things work?

Proving that an inductive loop sensor works is like proving there is no such thing as a UFO. Who’s to say the light wouldn’t have changed anyway? But, anecdotally, I would say they seem to work.

What trips the sensor?

Metal. It’s just a big metal detector in the pavement. It might help if you have a titanium hip like my mom, who sets off the metal detector every time she goes through airport security.

Does it matter how you park your bike over the loop?

As I understand it, the best way is to have both wheels touching the cuts in the pavement where the loop was installed. (By the way, if you have carbon fiber wheels, this probably won’t work. But if you have carbon fiber wheels, you can probably afford the citation, so just go ahead and run the red light.)

Also, I’ve noticed that in a couple of places around town they’ve painted markings showing where your wheels are supposed to be.

OK, so if you are the kind of person who pages through the Oregon Bicyclist Manual, you will find a diagram (shown at right) of a suggested method for activating one of these loops. Have you seen this method? Do you do this?

If I had to do that, I think I would just wait for a truck to pull up alongside me and trigger the loop out in the traffic lane.

We were corresponding about these loops with the city of Eugene’s traffic engineer, a gentleman named Tom C. Larsen. We showed him this diagram. His response: “The pictured leaning technique would help make a metal object more obvious to the inductive loop, but I would say is not necessary for normal operation.”

I’m glad to here that — because is there not something strange and vaguely obscene about that diagram?

I think it’s important that we move on and mention another kind of inductive loop sensor, don’t you?

Yeah, here’s one I’ve seen at Coburg Road and Beltline. Why is this loop so far back from the intersection? Am I supposed to park way back there and wait?

No. I was wondering about this, too. So we asked Larsen about this, as well. He said this is an “advance loop.” So, say the light is green and is about to turn to yellow. And here you come, trying to make it through the green light. If you ride over that loop, it is supposed to extend the green light a bit, to give you time to get through the intersection.

You don’t say? But, hey, did one of these have something to do with that bad-karma experience we mentioned earlier?


What happened?

I was heading south on Coburg Road, coming up to the light at Oakway, right there by P.F. Chang’s. The light had been green for a while. There is one of these “advance loops” there. So I rode over it. Then, just as I started to enter the intersection, the light changed to yellow.

So the advance loop didn’t work?

Well, I don’t know. Maybe I didn’t hit it right. But I went for it anyway. It’s a long crossing, this intersection. So the light went red before I had fully crossed the street. At which point there was a loud, angry horn blast from a car that was waiting to enter the intersection from Oakway.

Did you think the horn blast was necessary for anyone’s safety?

No, I think it was an expression of anger, impatience and general jerk-ness.

So after having been critical of cyclists who run red lights in the last post, you were promptly running a red light yourself and getting honked at by some angry, impatient jerk in a car?

I justify it by saying I was testing out the “advance loop.”

Yeah, well, it serves you right.

I should also mention that I was riding an Xtracycle with another bicycle frame, a 1970s-era Miyata, lashed onto the back. So, while I was hauling a lot of metal to hopefully activate the loop, I also looked perhaps like I could have been some kind of militant, car-hating bicycle freak.

Yeah, the kind of oddball who carries a bike on a bike. So why did you have a extra bike frame on the back of your Xtracycle?

That’s a story for another post.

OK, at Sixth and High, there is a loop. And there is also one of those older posts with a button that a cyclist is supposed to be able to press to tell the traffic signal someone is waiting. See:

Does that button still work, too, even though there is also a loop?

Apparently, yes. Larsen says:

“Our current standard would be to install in-pavement loops, not push buttons. Sixth and High has been upgraded to the passive loops.  In a perfect world we would have taken out the push button at the same time. We didn’t. I can’t really say why. The button is still active so we have redundant systems at that intersection. Because it still works, I probably won’t rush out and remove it.”

Say, which costs the city more? Inductive loops or push-button posts?

On this question, Larsen says:

“My sense is that cyclists very much prefer the passive loops, and that’s why they became our standard for new construction.  … Cost is an ‘it depends’ item. Retrofitting either (a post or a loop into an intersection) can become expensive. Our standards are based more on utility and functionality than an initial cost. Push button posts close to the edge of the road are often hit by errant drivers and need repair. … Loops do fail and do need repair or replacement, just not as frequently.”

Media training?

Perhaps … but gracefully answered, nevertheless.

3 thoughts on “Red-light techniques for the urban cyclist, Part 2: Loopy

  1. “My sense is that cyclists very much prefer the passive loops, and that’s why they became our standard for new construction. … ” I wonder if Larsen actually polled any cyclists? I very much prefer not to unclip when I have to stop at an intersection, so I personally like a post better.

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