Triggering traffic lights

[imellor]

Not specifically an electric bike issue, but still relevant.

I read on an American website that it is a good idea to place a couple of strong magnets under your bottom bracket.

The idea is that when you stop at traffic lights the inductive loop in the road is unable to detect a bicycle due to the limited mass if metal as opposed to a car. Adding the magnet distorts the magnetic field of the inductive loop and hence alerts the traffic light control gear that a vehicle (your cycle) is waiting.

What do you think, is this technically sound, or an urban myth?

Regards

Ian

 

[flecc]

Our loops are usually on the approach to the lights so measure the passing of more than one vehicle, I think up to three or four waiting between the loop and the white line. It would probably be necessary to trigger the approach loop repeatedly to have an effect.

Having said that, a strong magnet probably would have a disturbance effect sufficient to be read as a vehicle of some sort. The average Alnico magnet would be heavy though, I'd want something lighter like a neodymium one, but any benefit at the lights is probably too small to bother.
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[Mussels]

I'm guessing my ebike has some fairly strong magnets in it but it's not enough to trigger the older lights on my way to work, thankfully most have motion detectors up top so they do see me. Having traffic lights ignore me makes it easier to justify me ignoring traffic lights.

 

[dan]

Not specifically an electric bike issue, but still relevant.

I read on an American website that it is a good idea to place a couple of strong magnets under your bottom bracket.

The idea is that when you stop at traffic lights the inductive loop in the road is unable to detect a bicycle due to the limited mass if metal as opposed to a car. Adding the magnet distorts the magnetic field of the inductive loop and hence alerts the traffic light control gear that a vehicle (your cycle) is waiting.

What do you think, is this technically sound, or an urban myth?

Regards

Ian

Most if not all traffic lights in london are computer controlled from a central point....I would have thought it would be the same in most cities.

 

[Mussels]

Most if not all traffic lights in london are computer controlled from a central point....I would have thought it would be the same in most cities.

The computer still uses information from the sensors to see if any vehicles are waiting, if the sensors don't detect a vehicle the lights might not change.

 

[imellor]

Our loops are usually on the approach to the lights so measure the passing of more than one vehicle, I think up to three or four waiting between the loop and the white line. It would probably be necessary to trigger the approach loop repeatedly to have an effect.

Having said that, a strong magnet probably would have a disturbance effect sufficient to be read as a vehicle of some sort. The average Alnico magnet would be heavy though, I'd want something lighter like a neodymium one, but any benefit at the lights is probably too small to bother.
.

I've just ordered a Neodymium one from Ebay, so I'll let you know if it works.
I certainly hope it will trigger the right turn at West Croydon, so I don't have to keep waiting for a bus or tram to turn up behind me.
(Although I don't think that set have an inductive loop!!! I'll have a look next time)

Ian

 

[Mussels]

I've just ordered a Neodymium one from Ebay, so I'll let you know if it works.
I certainly hope it will trigger the right turn at West Croydon, so I don't have to keep waiting for a bus or tram to turn up behind me.
(Although I don't think that set have an inductive loop!!! I'll have a look next time)

Ian

I see some in London that need special tags to trigger the lights so there is usally a Pelican crossing style button for cyclists to push.

 

[BertYardbrush]

Many lights seem to have a thing that looks like a camera mounted above them. I think this is some sort of motion sensor. I believe that the sensitivity of this instrument can be adjusted. Our local cycle campaign group has written to the council and had lights adjusted to sense the presence of cyclists approaching.
I am not confusing this with the red light jumping cameras that there are in some parts of the country.

 

[HarryB]

I am not confusing this with the red light jumping cameras that there are in some parts of the country.

Annoyingly I haven't managed to trigger these cameras or speed cameras for that matter, though I suspect that has less to do with my mass than the pathetic speeds I achieve.

 

[flecc]

I certainly hope it will trigger the right turn at West Croydon, so I don't have to keep waiting for a bus or tram to turn up behind me.

Since that junction follows the bus station, I wonder if that has some bus controll? Some change sequences in London are able to be triggered by the bus driver on approach.
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[Alex728]

Many lights seem to have a thing that looks like a camera mounted above them. I think this is some sort of motion sensor. I believe that the sensitivity of this instrument can be adjusted. Our local cycle campaign group has written to the council and had lights adjusted to sense the presence of cyclists approaching.
I am not confusing this with the red light jumping cameras that there are in some parts of the country.

Ipswich cycle campaigns mailing list is monitored by various Council staff, from elected Councillors to various other officials.

When I mentioned one of these detectors in passing I received an official email from a traffic control engineer apologising for the problem and assuring me it would be corrected!

whilst it didn't happen immediately, the lights did get adjusted..

 

[BertYardbrush]

On a flight of fancy ... I have very little electrical knowledge .... maybe you could fix up an electromagnet to run off your battery to be switched on every time you approach a set of lights.

 

[Mussels]

Annoyingly I haven't managed to trigger these cameras or speed cameras for that matter, though I suspect that has less to do with my mass than the pathetic speeds I achieve.

I used to trigger those warning signs when I had a big torch mounted on the front, after I removed it my radar footprint must have shrunk as I no longer set them off. Occasionally when a car passes just in front of me they will then display my speed so they can see me but generally ignore me.
I need a tin foil hat to alert them to my presence.

 

[Mussels]

On a flight of fancy ... I have very little electrical knowledge .... maybe you could fix up an electromagnet to run off your battery to be switched on every time you approach a set of lights.

It will have to be pretty powerful to create a significantly stronger field than your motor.

 

[flecc]

Our motors have very little external field as a check with a screwdriver or other steel object will show, the design concentrates and focuses the field where it's needed.

An additional magnet would be best placed under the bottom bracket as low as possible with one pole focused vertically downwards. The current needed for an electromagnet would be to great for our batteries, a permanent magnet is best.
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[lemmy]

At very obstructive lights, I get off the bike and walk across them.

I checked with a cop and it seems that a person wheeling a bicycle is a pedestrian in law.

 

[flecc]

I checked with a cop and it seems that a person wheeling a bicycle is a pedestrian in law.

Indeed, here is the legal justification:

"Anyone pushing a bicycle is a "foot-passenger" (Crank v Brooks [1980] RTR 441) and is not "riding" it (Selby). In his judgment in the Court of Appeal in Crank v Brooks, Waller LJ said: "In my judgment a person who is walking across a pedestrian crossing pushing a bicycle, having started on the pavement on one side on her feet and not on the bicycle, and going across pushing the bicycle with both feet on the ground so to speak is clearly a 'foot passenger'. If for example she had been using it as a scooter by having one foot on the pedal and pushing herself along, she would not have been a 'foot passenger'. But the fact that she had the bicycle in her hand and was walking does not create any difference from a case where she is walking without a bicycle in her hand."
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[rosjen]

As this would only be a problem when there is no traffic you can just lean your bike, the more horizontal position creates a larger metal footprint - I have to do it to get out of our gates at work.

 

[Alex728]

As taxpayers, why not just contact the Councils? Although the call centres are sometimes overloaded and slow to answer, if your local cycling campaign doesn't do this (not every area has one) there are websites like fixmystreet where these things can be reported.

That way the lights gets fixed for everyones benefit. I'd always get the call log number from Reading Borough Council when I lived there and would chase the progress after a week but I actually very rarely had to do this!

Ipswich by and large works apart from a couple of lights on bus lanes (signposted for cycles) which do not correctly trigger at night. In these cases I simply move on when the light in the next car lane (in the same direction) is green. "naughty" perhaps but not dangerous (as the lights on the other side would be red anyway")

Rather curiously the light seems to work in daytime whether or not there is a bus. I wonder if this is a deliberate compromise to keep cars out of the bus lane at night as there is no CCTV up that end of town yet, but at daytime cops and PCSOs do patrol.

I think modern systems are actually quite complex and there is a trade off between recognising bicycles and the risk of false detection, which cause confusing signals and could put road users in more danger.