Triggering traffic signals with magnet?

[Bmblbzzz]

I rang the police on this one, and got the curt answer " no one can give you permission to go through a red light"

Highway Code?

Does that not count?

Rule 176
You MUST NOT move forward over the white line when the red light is showing. Only go forward when the traffic lights are green if there is room for you to clear the junction safely or you are taking up a position to turn right. If the traffic lights are not working, treat the situation as you would an unmarked junction and proceed with great care.

It depends on what is meant by "not working". It would probably come down to a court's decision in the case. When I took my motorcycle test I went through a set of lights that were definitely not working; they were not showing any lights in any direction. It's not a common occurrence but I remember the procedure which I'd been taught: Stop at the stop line. Do your checks, right, left, right, behind. Proceed to the edge of the junction if road between stop line and junction is clear (pedestrians obviously being the ones to look out for there). Stop. Treat as stop line.

I passed the test -- but I wonder if I would have done if I'd approached those lights on the main road rather than on a side road (T-junction)? Where one road is clearly "more major" than the other, traffic on the major road doesn't tend to stop for broken lights. In practice, we have an unofficial priority/non-priority system as is official in many countries with the white and yellow diamond sign.

[ambodach]

There appears to be a system in place on Connel bridge near Oban which is a single carriageway controlled by lights. This seems to detect bikes on the bridge after the traffic lights. If there is a long wait after the last car has gone past one way then eventually a bike appears before the change to green. No idea how it works as I always just cycle on the narrowish pavement so long as there are no pedestrians coming toward me. This is common practice here but probably illegal. Easier all round anyway since I am not exactly a speed merchant nowadays.

[mjr]

In a slight thread swerve, I am reminded of the cases where people have been fined for going into a bus lane or crossing a red light line when an emergency vehicle has behind them, going 'blues and twos'. I have little sympathy for the whiny, entitled crybabies who make up the overwhelming majority of the British driving public, but on this one, I can't see how it can be right or just to penalise someone who in a gesture of compassion moves out of the way of an ambulance which might be rushing an infant on the brink of death, to hospital.

The stop line is a limit not a target and you should stop far enough back to give you some wiggle room in case a blue-light vehicle comes up behind... and I don't understand why you would go into a bus lane because that's likely to be the clearest lane for the ambulance.

Most British drivers are rubbish at allowing themselves enough space to deal with reasonably predictable but unusual events like these. Fine them until they learn and don't give in to their squawking.

[thirdcrank]

I rang the police on this one, and got the curt answer " no one can give you permission to go through a red light"

If a traffic light isn't working, it's not "lawfully erected" and it may be passed with due care and attention, ie, you cannot simply ignore it. If traffic had to wait at a traffic light stuck at red, we'd get some long queues. Put another way, you don't need permission.

Rule 176
You MUST NOT move forward over the white line when the red light is showing. Only go forward when the traffic lights are green if there is room for you to clear the junction safely or you are taking up a position to turn right. If the traffic lights are not working, treat the situation as you would an unmarked junction and proceed with great care. (My emphasis)

The police have powers under the Road Traffic Acts and the Common Law to direct traffic and if you insisted on obeying a red light in preference to a police officer directing you to ignore you would risk prosecution (The main decided case I can remember was a driver who refused to reverse "the wrong way" on a one-way street when directed by the police to allow a public ambulance to pass in an emergency.)

Rule 105
You MUST obey signals given by police officers, traffic officers, traffic wardens (see ‘Signals by authorised persons’) and signs used by school crossing patrols.

Otherwise, the HC seems clear that you may not ignore traffic signs to allow emergency vehicles to pass. AFAIK, this usually crops up if somebody triggers a traffic light enforcement camera.

Rule 219
Emergency and Incident Support vehicles. You should look and listen for ambulances, fire engines, police, doctors or other emergency vehicles using flashing blue, red or green lights and sirens or flashing headlights, or traffic officer and incident support vehicles using flashing amber lights. When one approaches do not panic. Consider the route of such a vehicle and take appropriate action to let it pass, while complying with all traffic signs. If necessary, pull to the side of the road and stop, but try to avoid stopping before the brow of a hill, a bend or narrow section of road. Do not endanger yourself, other road users or pedestrians and avoid mounting the kerb. Do not brake harshly on approach to a junction or roundabout, as a following vehicle may not have the same view as you. (My emphasis.)

[kwackers]

Rule 176
You MUST NOT move forward over the white line when the red light is showing. Only go forward when the traffic lights are green if there is room for you to clear the junction safely or you are taking up a position to turn right. If the traffic lights are not working, treat the situation as you would an unmarked junction and proceed with great care. (My emphasis)

I'd be interested in knowing what constitutes "not working".
I'd put good money on it that actually being lit up at all would have some jobsworth claiming they were working (probably then demonstrated by using the patrol car to trigger them).

[Mick F]

I'd be interested in knowing what constitutes "not working".

Me too.
Just like what has been said earlier.

I looked at the links supplied and saw the bit about passing through traffic lights that are not working, but not the about traffic lights working, but faulty. I go through them if I think they are stuck on red, but if stopped by a policeman, I am not sure where my argument would come from.

Not working?
What about "not working properly"?

[thirdcrank]

... I'd be interested in knowing what constitutes "not working".
I'd put good money on it that actually being lit up at all would have some jobsworth claiming they were working (probably then demonstrated by using the patrol car to trigger them).

I cannot point to any cases here but the onus is on the prosecution to prove a case. Obviously, few people want to get as far as court just to gain fame - or not - as the (insert name of junction) One. All I can say is that one of the "points to prove" in a traffic light offence always used to be that they were working properly. Presumably it still is. I think that if a police officer demonstrated that a set of lights was activated by motor traffic, it would be reasonable to ask to demonstrate with your bike that they didn't work for you. (NB, once upon a time you could have kept schtum and popped up with it at court but the current caution would make that risky.) I think one thing in your favour would be that a typical police officer might not know the bit about the three sensors. I only discovered it after retirement when I became involved in cycle campaigning. Unless there was really good evidence that the lights were working properly eg computer log then I think the CPS wouldn't touch it.

If somebody suggests you should have dismounted and walked, it would be just the time to mention that the legislation includes the word "propel." (And thank YOS for being so thread-to-needle with RLJ .. er ... threads.

This is all part of my rationale in recommending that riders report lights which don't detect the approach of cyclists. (A) They may be fixed to everyone's benefit (B) If they don't there should be a record dated before you were stopped which would be good evidence.

I only remember one case of my being spoken to by the police (words I choose carefully) about passing a traffic light at red, which I knew from experience did not detect an approaching cyclist. I was riding home from half nights at about 0230 in steady rain and as I approached the lights I looked around and nothing was coming that would have activated them so I rode through at moderate speed. A short way further along the road, a marked police car drew alongside, the window went down and the sergeant in the front passenger seat remarked "Traffic lights apply to you like everybody else, young man." (FWIW, I was by then in my mid forties.) His tunic was unbuttoned and the seat was half reclined. I said nothing and just pedalled steadily on. I wasn't looking for any sort of confrontation but I thought if you are going to deal with this you can button up your jacket and get out here in the rain. After what seemed like an age of silence but was probably only a couple of seconds, the driver decided to clear off and that was the end of it. By coincidence, my next posting was onto their shift at the now-demolished Dudley Hill Police Station. At some stage, they must have twigged it had been me because of my cycling to work but it was never mentioned.

[MikeF]

I can remember when traffic lights were controlled by raised pads in the road. When I was at school a new set of lights had just been installed in the town. This prompted a discussion about their operation amongst a group of us walking nearby. So in order to test the operation of the pad, a line of us jumped in unison on the pad to try to see if the lights changed. I'm not convinced we changed them - maybe it needed more weight.

Sign of the times regarding the traffic, but not teenagers' behaviour. But it was all in the interest of science.

Back on subject. I've only come across one set of lights that haven't changed for me. I do have a hub generator and a small magnet for the cateye computer but I'm surprised if this is significant. I usually ride a steel framed bike and maybe this makes a difference. It would be interesting to know whether the frame material ie Aluminium/ Steel makes a difference. What happens with a carbon frame - obviously there are small metal parts but I bought if these are significant? Some traffic lights have radar sensors as well eg temporary ones, and these seem to "pick up" cyclists.

[Patrickpioneer]

Well the magnet failed but mjr's suggestion works, ride on the edge of the sensors not down the centre as I was doing. At last I can get across the road
Pat

[MikeF]

Today I wanted to turn right at a set of traffic lights but my bike wouldn't trigger the lights even though I was on/over the sensor. A short queue of cars started to build up so I pressed the pedestrian buttons which were in easy reach to make them change.

[Patrickpioneer]

BTW, if you like me have a big magnet, just chuck it in a metal cat or dog dish and you have a magnetic dish for your bits.
Not a lot of people know that.
Pat

[Brucey]

They used to be pricey, but magnetic dishes start at about £2.25 these days on flea-bay for a small one;

https://www.ebay.co.uk/sch/i.html?_nkw=magnetic+parts+dish

Worth noting that if you use stainless steel screws, a magnetic dish won't retain them very well; most stainless steel screws only contain about 5% ferrite and are very weakly attracted to a magnet.

cheers

[andrew_s]

A magnet isn't very useful for triggering traffic light detector loops. They work more like upside down metal detectors.

[Redvee]

Another way of getting the lights to change is to reach for your watert bottle or start adjusting your clothing, it works for me and means I've had to ride away from lights with a zip undone or waterbottle in my mouth where I've been caught out.

[Brucey]

its all very interesting.

Coils are laid out in various different ways



and here

http://www.humantransport.org/bicycledriving/library/signals/green.htm

it explains that you should position your bicycle differently over different layouts of coil if you want to be detected. It rather begs the question as to what the best position is to activate loops which are shaped like 'sergeant's stripes' if you like...?

Here
https://marshproducts.com/PDF/Inductive%20Loop%20Write%20up.pdf

it explains that the resonant frequency of the inductive loop is changed and that is what causes the detection event. On the face of it this relies on eddy currents alone (so it mayn't matter too much if the metal is ferromagnetic or not) but in practice the way the flux linkage is changed as eddy currents are developed is also dependant on the magnetic state of any steel that is within the detection zone, e.g. the slope of minor loops in the B-H plot of steel isn't constant with varying levels of B field. [This is (sort of) analogous to 'bias' in tape recording, I think.]

Anyway I ride different bikes over the same sensors on a regular basis (and even the same bikes with different wheels in ) and it seems to me that if I have a hub generator fitted the sensor is more likely to react to me. This could just be a fanciful notion I suppose!

cheers