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good post! i was driving in my car the other night with my dad and he asked what all the squiggly tar marks were on the road right before the stop line and said that he always wondered what those were for. a moment to shine for me as we had been taught in driver's ed that there was a magnetic sensor so if you are in a car or a motorcycle pull up so that the engine compartment/hood is right over that black loop on the pavement so that it picks up a vehicle waiting at the light. as my ex knows i snoozed thru a lot of the course material, but this part i managed to be awake for lol. good little tip - only thing that sucks is when u get caught behind the seniors that aren't so up to date on these things and they stop at lights about 6 feet from the stop line and u end up waiting until someone on the other side of the intersection pulls up to the right spot.
 

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Mmm...beer
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Nice find.
 
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just to clarify janet, it's not a magnetic sensor. it's an inductive loop that creates an electrical signal when a metal is passed over it. it's the main reason why bikes have a hard time tripping the lights. the aluminum and other non-ferrous alloys do not generate the same induction that steel does. we used to be able to trip "secure community" driveway gates with 6" electrical box covers slid over the sensors. was great when we couldn't get into a gated community to do service work. we ended up having one labelled as the "master key".

another sensor used is a photo sensor. it detects light. you can flash your high beams at it and have the lights change well before you have to brake at the intersection.
 

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West Koots, I'm here....
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Discussion Starter · #6 · (Edited)
just to clarify janet, it's not a magnetic sensor. it's an inductive loop that creates an electrical signal when a metal is passed over it. it's the main reason why bikes have a hard time tripping the lights. the aluminum and other non-ferrous alloys do not generate the same induction that steel does. we used to be able to trip "secure community" driveway gates with 6" electrical box covers slid over the sensors. was great when we couldn't get into a gated community to do service work. we ended up having one labelled as the "master key".

another sensor used is a photo sensor. it detects light. you can flash your high beams at it and have the lights change well before you have to brake at the intersection.
I think I recall reading in the article that they state it's an inductive loop. "There are all sorts of technologies for detecting cars - everything from lasers and cameras to rubber hoses filled with air! The most common technique, by far, is the inductive loop. An inductive loop is simply a coil of wire embedded in the road's surface that acts somewhat like a magnet."

Doug, you don't have to explain these traffic systems to me, that's my specialty in electrical. I have designed intersections, built and programmed the traffic signal controller, and installed all the wiring and controller at the site. The intersection at 100 Mile House near Tim Horton's was a project of mine while spending 6 months at the MOTH traffic signal engineering dept.

On the Barnett Hwy at the refinery intersection, MOTH was experimenting with video detection for activation, and I set that up as well. I don't know what is presently there, as it is no longer under the jurisdiction of MOTH.
 
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Doug, you don't have to explain these traffic systems to me, that's my specialty in electrical.
i wasn't explaining for you. we've talked about our qualifications in the past, and i know you've had a lot more experience working in traffic systems than i have. i was clarifying for the other janet, janesee.
 

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West Koots, I'm here....
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Discussion Starter · #8 ·
i wasn't explaining for you. we've talked about our qualifications in the past, and i know you've had a lot more experience working in traffic systems than i have. i was clarifying for the other janet, janesee.
Ah, got it. Sorry for my confusion then, and now I recall our previous discussions, but if I remember correctly they were at a time of distress (?).
 
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I hate it when people stop a few feet back of the censors. Honking and inching forward to the clueless doh head infront of my to move up, or for another car to come to the lights in the opposite direction.

Doh Heads!
 

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West Koots, I'm here....
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Discussion Starter · #10 ·
I've also been at an intersection which I couldn't activate with my bike, so I moved ahead and signalled the car behind me to close up to me, thereby getting it over the loop. But sometimes you just get the clueless driver who hasn't ever even noticed a tar loop in the road and has no idea what it's for.
 

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Jackie Chan's stuntdouble
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just to clarify janet, it's not a magnetic sensor. it's an inductive loop that creates an electrical signal when a metal is passed over it.
A further clarification is that the inductive loop is essentially a metal detector, not a magnet detector. Don't waste your money buying a permanent magnet to attach to your bike when a chunk of scrap iron will work better.
 

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I am the liquor
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I think it was TeeTee that once said that if you have trouble triggering a loop on you bike then you can try putting you kickstand down close to the rubber line in the road, which might help trigger it. Sorry if I am misquoting you TeeTee, thats just what i remember from the post. Perhaps you can clarify?
 

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A further clarification is that the inductive loop is essentially a metal detector, not a magnet detector. Don't waste your money buying a permanent magnet to attach to your bike when a chunk of scrap iron will work better.

that's what i meant to say - metal sensor, not magnetic - but thanks for the clarification doug, that's just the way it was explained to us in driver's theory. in my motorcycle course we did our day and night ride in nanaimo and encountered several intersections with this inductive loop, and the bikes didn't seem to have any problem triggering the sensor. we tested this at a light that crosses a main street and has little to no crossing traffic. the light changed as soon as my bike came to a stop over the loop.

and flyfishinwoman - we share a great first name lol, i'm a janet too:rockon
 
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