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Magnetically Managed Speeders

Make 'em slow with eddy current flow
  (+7, -4)
(+7, -4)
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To slow down speeders near schools, ahead of crosswalks, stop signs, etc. a permanent or electromagnet could be embedded in the roadway. The latter would be activated by radar upon the approach of a speeding vehicle. As the conductive car frame passes through the magnetic field, induced eddy currents cause an opposing force that slows it. Any current produced could be bled off to the city power grid.
FarmerJohn, May 27 2002

Regenerative braking system for cars http://www.halfbake...system_20for_20cars
I mentioned a v. similar idea to this in an annotation here [hippo, May 27 2002, last modified Oct 05 2004]

Smart car for stupid drivers http://www.halfbake..._20Stupid_20Drivers
...and here too. [hippo, May 27 2002, last modified Oct 05 2004]

streetlight motion detectors http://www.halfbake...20motion_20detector
...and here! I must stop posting this annotation... [hippo, May 27 2002, last modified Oct 05 2004]

Millennium Force http://www.darkstud...com/c2c/051100.html
Roller coaster at Cedar Point in Sandusky, Ohio. Uses magnetic brakes. [phoenix, May 28 2002, last modified Oct 21 2004]

[link]






       On the condition that you include safety features to stop the next car plowing into the back end of the slowing vehicle, pastry.
yamahito, May 27 2002
  

       Most cars have magnetic sensors for ignition timing and other engine management functions. A magnetic field capable of appreciably slowing down a car might also incapacitate those systems - and maybe wreck the tyres and suspension due to the extra load on them.
neelandan, May 27 2002
  

       in reference to both the last two annos: serves 'em right for speeding past a school!
yamahito, May 27 2002
  

       Not that I'm advocating speeding, particularly near schools, but...
Have you noticed that, whenever car/pedestrian accidents occur where the car was doing a legal speed and the pedestrian was wandering around like a blind half-wit, the official response is always to reduce the speed limit.
angel, May 27 2002
  

       That's the beauty of it. Nothing has to be added to (or can be taken away from) standard makes. The faster or heavier the vehicle, the stronger the braking force acts on it.
FarmerJohn, May 27 2002
  

       I think that what UB meant was that those vehicles are almost entirely fibreglass...
mwburden, May 27 2002
  

       At least the engine and transmission should decelerate.
FarmerJohn, May 27 2002
  

       A magnetic field of sufficient strength might also relieve the little bastards round my neck of the woods of the machettes and flick-knives they come to school armed with.
brewmaster, May 27 2002
  

       And, to be fair, that's probably most of the weight right there.
yamahito, May 27 2002
  

       [mwburden] Except for Land Rovers, which are Aluminium
(The British Government, after World War II was almost penniless and gave generous tax breaks to anyone who could bring in export sales. Rover cars thought they could do this with a general-purpose vehicle for developing countries - the only problem with this was that steel was hard to get hold of because it had all been used up in the war, so they chose aluminium instead)
hippo, May 27 2002
  

       Anything to stop Mothers in Hummers (ie: the mother dropping off the kids in the Jeep Cherokee, then speeding off, knocking over schoolkids as they go.
thelumberjack, May 28 2002
  

       I think some annotators are a bit confused about eddy current braking. The affected parts need not be magnetic, but electrically conductive. Aluminum would work just fine. Better in fact because it is more conductive than steel. Fiberglass would be unaffected, however.   

       The biggest problem is that a sudden, unexpected decrease in speed would probably cause a crash more often that it would prevent one. Startled drivers tend to panic and swerve in unpredictable ways.
BigBrother, May 28 2002
  

       "I think some annotators are a bit confused about eddy current braking. The affected parts need not be magnetic, but electrically conductive."
Count me in. How do you grab onto aluminum with a magnet?
phoenix, May 28 2002
  

       Phoenix: the point is, you're not using what you might think of as the magnetic interaction, but an electromagnetic one. remember doing things with motors and dynamos in school? same thing - an electric charge moving through an electric field produces a force sort of thing. When this happens, it can be shown that the force will always oppose a direction of motion.   

       The thing is, the charge does not have to be in a magnetic medium, so aluminium would be fine too.   

       I have to admit, i've always been bad at electromagnetics, so pls excuse me if I got something wrong - it's been a while.
yamahito, May 28 2002
  

       Okay, but that implies a path for current flow, doesn't it?
phoenix, May 28 2002
  

       The idea is OK, but I don't trust the government to only put them in front of schools. The next thing you'll see is the technology being sold to retailers trying to get people to stop at their establishments.   

       Also, what an opportunity for car-jackers!
bspollard, Sep 16 2002
  

       I think custard would be a better (and tastier!) way to slow down cars.   

       A magnet that is big enough to stop a car by induction would also likely be big enough to rip all that shrapnel you got in 'Nam right out of your legs.
gastronaut, Apr 07 2003
  

       Sorry to disapoint all the gorre seekers, but the car has to pass through a uniform electric field. This means its not actually being attracting in any direction. Same as iron isnt affected by the earths magnetic field, as its the same strength all around. It would, however, 2 large coil loops at the side of the road, with a few thousand volts going through it. And outside the coils the magnetic field can be huge.
miasere, Apr 07 2003
  

       [angel] As I understand it, the rationale behind lowering the speed limit is to reduce the damage done to aformentioned loony pedestrian when they get hit. Also it reduces your breaking and reaction distance so you would be less likely to hit them.   

       Last night a lady with a push chair didn't bother looking and walked straight out in front of me, If I'd been going ten miles an hour faster there would now be two more winged harp players.
rambling_sid, Dec 23 2004
  

       Perhaps schools should be placed somewhere where there are no roads.... Sigh I can hear people talking about pedestrian zones can't I?   

       Solves all the problems... mums can't drop there kids off and you can drive as fast as you like.
madness, Dec 23 2004
  
      
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