Traffic Lights and Magnets

E

Eclectic

1 kW
Joined
Aug 6, 2012
Messages
308
Location
Southern California (San Gabriel Valley)
Like everyone else (I assume) that uses 2 wheeled transportation, I am frustrated with traffic light sensors that don’t “see” me. I searched around on the net and saw a lot of stuff on using magnets. I tore apart a couple of old hard drives and put the magnets on my pedals. I seemed to get about a 25-30% improvement in triggering traffic lights.

Unfortunately I didn’t change things in an organized manner. I added some magnets with the Mu-metal attached and some magnets just wrapped in pvc heat shrink. I also changed my behavior. I now try to place my lower pedal directly on top of the cut in the street where before I always tried to center my bike on the whole sensor. My problem is that right now all I have is some anecdotal evidence that it might work.

Since I only have a very basic understanding of how an induction sensor works, I thought I might ask others who probably have a much better understanding of magnetic flux and sensors; does the theory work? Can a small molybdenum magnet or a small piece of Mu-metal close to the sensor wire actually change the inductance enough to trigger the sensor?
 
Steel toe shoes seem to work if you stand on the line and slide or wiggle your foot. :wink: I used to carry a magnet on a rope for fishing and reeling up tool road kill, never tried it to change the light to green though. :?
 
This was previously brought up a few times and ends up in the same place. Magnets don't work, although some have anecdotal evidence to the contrary. There just hasn't been a single perfect solution for ebikes.

Here's the latest thread:

Red Light Changer / Induction Loop Thread
 
My favorite solution is the one where I live. Bikes and motorcycles can treat red lights as stop signs if they are pole position due to the poor technology not detecting them. Although I would probably trade that for your lane splitting laws in CA with the amount of city riding I do.
 
I pulled up to a red light on my DRZ-400S. I knew that the sensor would not see me, but there was a car behind me, so it seemed ok. I pulled up a few feet *past* the stop line so that the car could get close.

The car stopped about 30 feet behind me!

I had to turn and wave to them and point to the ground to get them to move forward, but it seemed likely they did not understand my intention, and only moved up a few feet.

When I am alone, I either wait one full cycle, and then go through it, or make a right, then a u-turn, then another right.
 
cal3thousand said:
This was previously brought up a few times and ends up in the same place. Magnets don't work, although some have anecdotal evidence to the contrary. There just hasn't been a single perfect solution for ebikes.

Here's the latest thread:

Red Light Changer / Induction Loop Thread
Click to expand...

Thanks for the link. I thought I remembered some threads here (looks like they have been combined now) but searching for Magnets on ES was not very useful. I guess "Red Light" was the key word I should have been looking for. I know the info is often here someplace, it's just so hard to find it.

And yes I do stop at red lights (although I sometimes do an "Idaho Roll" at a Stop sign if there are no other cars around). I try to follow traffic laws as much as possible (as long as I can do it safely). I like to be as predictable as possible and I feel that is best accomplished by following the laws and trying to be an ambassador for light vehicles in general.
 
I once put on my turn signal and waited to turn left into a parking lot. A car hit me from behind at maybe 30 mph. It destroyed the rear-end of my few-week old Sequoia. No one was hurt.

If they cannot see a 6000 lb car, I am not sure they could see a bike. If I were on a bike, I would have been launched 300 feet into the air.

Not sure what the solution is, but I am extremely concerned about stopping on the road on a bike if cars are behind me.
 
VA,SC,NC have addressed traffic actuated signals directly. Some other states may not, but I didn't goog for individual states. I usually due the right turn and a U, or treat the light like a stop sign when no one is around.

(pick state, and it's alphabetical to 'traffic actuated'.)
http://www.americanmotorcyclist.com/rights/State-Laws.aspx?stateid=25

MO uses 'affirmative defense'
http://www.moga.mo.gov/mostatutes/stathtml/30400002851.HTML

I would assume that states that haven't addressed this directly are still the same, or have less of a specified wait. It's a non-issue imo? And even less so for bicycles and pedalcycles.
 
I think it is a non-issue, because when you explain it to the police officer, they are unlikely to write you a ticket. Partly because the signal issue will make sense to them, and partly because they know that a judge or hearing officer will be annoyed at them if you take it to court.

At least if you wait a complete cycle and don't just blast through it.
 
Not sure what the solution is, but I am extremely concerned about stopping on the road on a bike if cars are behind me.
Click to expand...

Didn't mean to skip this; I'd say it's obviously the more important issue. I guess full alertness and a good education coupled with proper defensive and offensive driving is the best way to share the road with the bigger vehicles unscathed?
 
rsilvers said:
Flashing super LEDs should help.
Click to expand...
Drivers ram into police cars/etc at roadside, while said cars are flashing all their extremely bright and numerous lights.

I don't think lighting matters much if a driver isn't even looking. ;)



I haven't been hit (yet) from behind but I am always watching the vehicles approaching me when I am waiting at a light, day or night, because there have been a couple of times when if I was not, I *would* have been hit, but instead I was able to gun it and swerve one side or the other out of the way (once at night, once in daylight).

Same applies to any other situation--be aware of what's going on around you and have an escape plan. If you don't, then be prepared to be smashed at any moment, regardless of what you're riding or driving. ;)
 
Yes. I was standing next to a police officer directing traffic around construction. There were three giant orange signs leading up to him that said "POLICE OFFICER AHEAD" and a few dozen orange cones. Occasionally a car would drive past all of that and now slow down and not even follow his instructions to stay in the open lane. He even had white gloves on his hands. Maybe that was just one car out of 50 or 1 car out of 100, but it would happen several times a day.
 
What about this?

https://buy.garmin.com/en-US/US/into-sports/cycling/varia-rearview-radar/prod518151.html
 
A mirror has additional benefits of always being on, not needing batteries, and giving more information. I am going to order some mirrors now actually.

That radar thing would be nice wired into my bike battery, but I would not want to deal with removing it to USB charge it all of the time.
 
My cargo bike (all steel frame and large steel framed foot pads which sit low to the ground) seem to do a great job actuating street light and electric gate sensors. They have eliminated the frustrations of sitting and waiting for a few cycles of the traffic lights on a few occasions, but where they really shine is opening our driveway gate from the inside. Other lesser mass ebikes just won't do it :)
 
mikebikerad said:
Other lesser mass ebikes just won't do it :)
Click to expand...

Has nothing directly to do with just mass.

Has everything to do with magnetically reactive metals. ;)

Only has to do with mass in that there usually must be some critical amount of mass of the magnetically reactive metals.


Unless they are using a *weight* sensor, in which case even my heavy bikes laden with cargo probably wouldn't trigger them. ;) (and I've never run across a gate, traffic light, or other things for traffic/cars/etc triggered by weight sensors, here in Phoenix, AFAIK).
 
amberwolf said:
I don't think lighting matters much if a driver isn't even looking. ;)
Click to expand...

Oh they are looking .... at their cell phones.
 
I look right, I look left. If the coast is clear, I take off. I don't sit at red lights.
 
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