Vehicle sensitive traffic lights

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helston90

Eat, sleep, ride, repeat.
Location
Cornwall
In my town we only have one set of traffic lights but due to their layout are pressure sensitive to vehicles rather than on a cycle.

I approached them last night and clearly was not heavy enough to trip them (as I sat and watched them blissfully ignore me)

How would I excuse running the red light to carry on my journey? Short of jumping up and down on the sensors is there anything I can do?

Fortunately some cars came after about a minute of standing there- but I still felt rather daft having to wait.
 

screenman

Squire
With these lights if you get off of your bike turn around 4 or 5 times and wave your hands you will find they will change in time.
 

summerdays

Cycling in the sun
Location
Bristol
As far as I know they should be deemed as faulty and proceed with caution. However try reporting them. I had a set that refused to change for me and after complaining multiple times they finally adjusted it so that a bike did trigger the lights.

You need to look for the induction loops in the ground, and make sure you cross them, I think if you are having trouble triggering I've even heard it said that try crossing them at the edge, but I have no idea if that is true. Induction loops don't normally go as far as the gutter so it is another reason (if you needed one), not to cycle in the gutter.
 

GrasB

Veteran
Location
Nr Cambridge
You need to look for the induction loops in the ground, and make sure you cross them, I think if you are having trouble triggering I've even heard it said that try crossing them at the edge, but I have no idea if that is true.
The diamond shaped ones seem to be more sensitive if you go close to one of the corners but the short/wide parallelogram & rectangular ones I find work best if you pass through the centre of them.
 

Tim Hall

Guest
Location
Crawley
With these lights if you get off of your bike turn around 4 or 5 times and wave your hands you will find they will change in time.
Upto a point, Lord Copper. Lights tend not to be weight activated these days. Sure when I was young and the world was an innocent place, traffic lights were activated by pneumatic sensors set in the road. Squash the rubber tube and a puff of air switched a switch (more or less). These days there will either be a loop in the road or a doppler radar sensor.

The loop in the road (identified by a shiny, umm, loop in the road) is triggered by metal passing over the loop causing a flux in the space time continuuum the induction sensor to get triggered. To maximise your chances of detection, ride directly along the edge of the loop, so metal is "in the zone" for as long as possible. If riding with a buddy, attack both sides of the loop at the same time.

Doppler sensors look like video cameras without a lens, sitting on top of the light pole and are more often found on temporary traffic lights. They detect movement towards them, and should be sensitive enough to detect a bike. Whether the green cycle is long enough to get through the road works is another question, as I fouind out on Sunday. <killer of urban myth> what they don't detect is head lights being flashed. Not that anyone mentioned them yet. </killer>.

Anyway, back to the OP, if they don't detect you, do as others say and proceed with caution. And report them to the local authority. I've had the sensitivity on lights adjusted before.

(Edit; crossposted with GrasB and summerdays)
 

Sara_H

Guru
I ride on the edge of the loop on one of these, it seems to work ok for me. When it was first introduced it didn'y work for cyclists, but the council adjusted it after complaints.
 
If it's controlled by induction loop then it's my understanding that you need to have a quantity of steel or iron on you to trigger it. If your not ride g a steel bike you might not have enough ferrous material. No amount of silly dancing will trigger it. But what would I know, I'm a public servant.
 

Tim Hall

Guest
Location
Crawley
Tim, are you saying I have it wrong?
Yes, I'm fairly certain that turning around four or five times off the bike in front of an induction loop controlled light won't have any effect. Whether doing the same in front of a doppler controlled one will do is less sure.

I used to tell my kids that clapping their hands, while sitting in the car would make the traffic lights go green. Call it an early lesson in correlation vs causation.
 

the_mikey

Legendary Member
The spokes on a bicycle wheel leaning to one side should be enough to trigger a loop detector as long as the wheel is covering one side or corner of the loop. Corners seem most effective when I test loops (I am an Engineer and this is part of my job)
 
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