Triggering an inductive loop

[All uphill]

Its a bug bear of mine at traffic signals, especially as i am often out and about in the small hours when there is little traffic to help.

Ive reported several to TFGM and on several occasions had feedback from an attending engineer, usually along the lines of "I've turned the gain up" (read sensitivity) let us know how you get on. One particular set of ATS has an issue when emerging from a back street almost right on the stop line you wont go over the loop, they added an IR detector looking right down on the area before the stop line.

If ever you want to know more about ATS there is a chap the posts on sabre-roads forums he's either an ATS engineer or tech or similar.

Oh, you've just shown me a wonderful rabbit hole. Sabre roads.

Thanks, I think.

 

[markemark]

It’s actually a car signature frequency the sensors pick up. There’s and upper and lower limit frequency range and volume to trigger it. You need to either speak to the manufacturer but the easiest and quickest solution would be to cycle up and mimic the sound a car makes at the top of your voice. You may need to make lots of different car noises until you work out what works.

 

[Ming the Merciless]

You may need to make lots of different car noises until you work out what works.

Why not just record a real car, then play it on loud speaker on a loop as you approach ?

 

[cougie uk]

There's fantastically an inductive loop where bar a couple of houses to whom it is a benefit. means you need three cyclists together to make it change the lights on the end of an off road bridleway section of NCN67 in Harrogate. The highway engineers braincell worked enough to realise that would not work for horses so installed a push button at horse rider height

There's a crossing by me that has three separate crossings for pedestrians, cyclists and horses.

Only ever seen cyclists there so you can choose to pretend to be a horse if you can reach the button.

 

[Mike_P]

There's a crossing by me that has three separate crossings for pedestrians, cyclists and horses.

Only ever seen cyclists there so you can choose to pretend to be a horse if you can reach the button.

No chance of that. A bit of braincell and they could have put it lower and still be reachable by a horse rider, or even provide two but hey think of the cost.

 

[Tom B]

Oh, you've just shown me a wonderful rabbit hole. Sabre roads.

Thanks, I think.

You don't even want to know how I found it..... or actually one of the specialist sub sections of pointless geekiness.

....... Ill see you on the other side

 

[craigwend]

Cycle-Limbo?

 

[the_mikey]

I used to be an engineer that dealt with induction loops as a routine part of my job, they're usually set up with a few parameters, firstly they may operate on a number of frequencies (used when there are many different loops installed to prevent cross interference between them) , and they usually have a sensitivity control at least, and finally the logic settings that determine how it behaves when it detects or un-detects a vehicle, so it's quite simple in those terms. Large vehicles usually have no problem triggering loops, and even on the lowest sensitivity settings, something like a car will always trigger the loop, but at the lowest sensitivity setting motorcycles and bicycles usually struggle to trigger the detector, however the loop itself is seldom installed as a circle and will be cut into square, rectangle or diamond shapes, the corners of these loops are where the loop is most sensitive as you are able to influence a greater proportion of the loop, it doesn't matter which metal you use, aluminium will work, a bicycle wheel rim should be able to trigger it, but the trick is to cover as much of a corner of the loop as you can.

 

[Gwylan]

"Don't know what to tell you" "have to look into that" yep that's the response I get when it is mentioned. I am not looking to fix the industry stupid, just reliable trick to trip the sensors.

Make it a formal safety issue to the chief of elf safe tea. But you might like your job and the money.

 

[Mike_P]

it doesn't matter which metal you use, aluminium will work, a bicycle wheel rim should be able to trigger it, but the trick is to cover as much of a corner of the loop as you can.

How are you supposed know where the corners are?

 

[Alex321]

How are you supposed know where the corners are?

You can usually see the lines. I believe they are usually retro-fitted, by digging a narrow line in the tarmac, then covering with bitumen or something.

 

[HLaB]

O.k. here's the problem. The current employer uses some form of sensor to allow egress from the facilities. I have been unable to trigger this thing when heading out on my bike. Usually there is no keypad on the inside ( getting in is easy). I think it must be an inductive loop, not RFID, as random cars have no problems getting out. So it's the traffic light sensor problem. Ideas ?

Whoever in charge of it will be able to up the sensitivity of the loop signal receiver; its the same with traffic lights.
Separately from that I find riding over two sides of a loop slowly at the same time seems to trigger them. With the local traffic signals I find it has to be the top and bottom of all loops (there's a series of them) and not the sides or even close to the corners. Marginally too fast the signals won't trigger either or not clearing (rolling over them) in time can fail to trigger them too. With my old office which had a similar gate to you however, I found I had roll over the top and side bit of the loop close to the corner.

 

[Mike Ayling]

If they are sensing ferrous metal, then I would expect Alu (or Titanium) frames to be similar to carbon, but steel frames would be rather better than either.

[EDIT]
Apparently it is not frrous metal that is detected, but any conductive material - and with bicycles, it will mainly be the wheel rims that are detected.

So carbon frame will be fine if you have aluminium wheel rims, but if you have carbon wheel rims (even ona steel framed bike), detection will be much harder.

Also, from what I read, detection of the bicycle will generally be much easier at the edge of the loop than over the centre of it, unlrss it is a quad pole loop.

AFAIK carbon is a conductor.

 

[Mike_P]

You can usually see the lines. I believe they are usually retro-fitted, by digging a narrow line in the tarmac, then covering with bitumen or something.

I'll have a look next time. So if I stop the bike over the corner it should mean the lights change? How long should I need to wait before deciding to jump the red as normal?

 

[brommieinkorea]

I used to be an engineer that dealt with induction loops as a routine part of my job, they're usually set up with a few parameters, firstly they may operate on a number of frequencies (used when there are many different loops installed to prevent cross interference between them) , and they usually have a sensitivity control at least, and finally the logic settings that determine how it behaves when it detects or un-detects a vehicle, so it's quite simple in those terms. Large vehicles usually have no problem triggering loops, and even on the lowest sensitivity settings, something like a car will always trigger the loop, but at the lowest sensitivity setting motorcycles and bicycles usually struggle to trigger the detector, however the loop itself is seldom installed as a circle and will be cut into square, rectangle or diamond shapes, the corners of these loops are where the loop is most sensitive as you are able to influence a greater proportion of the loop, it doesn't matter which metal you use, aluminium will work, a bicycle wheel rim should be able to trigger it, but the trick is to cover as much of a corner of the loop as you can.

If nothing else I figured the query would yield entertaining results, but your mention of motorcycles made me wonder if the motor bikes were having issues, but I then remembered they're all Harleys with a large mass of metal and they are pretty low.