This is basically a sprung ramp built into the road. Cars approaching the ramp from the correct direction depress the spring thus flattening the ramp, and travel unimpeded. Cars approaching the ramp from the incorrect direction are faced with the vertical face of the ramp and thus cannot proceed.
This could be used in carparks, one-way streets, and normal roads.-- xaviergisz, Aug 10 2009 Fake speed bumps http://www.foxnews....2933,373123,00.html [ldischler, Aug 11 2009] 1st of all, baked by the one-way spike strips that they have in parking lots already.
2nd, you overlook the fact that the bump will spring back into its original position underneath your car and probably break something.-- DIYMatt, Aug 11 2009 A no-way speed bump would be novel. One that only looked like a speed bump--perhaps painted on the road.-- ldischler, Aug 11 2009 I think I read about that. (Paint-only speed bumps, I mean.)
This idea would be better than the "severe tire damage" spikes in that it wouldn't absolutely kill your tires if you have to go over, it would just require extra care and attention. Or the cooperation of someone going into the opposite direction.-- jutta, Aug 11 2009 Yep, it's supposed to be a gentler alternative to the road spikes for two reasons: a) no severe tire damage (as noted by jutta), and b) it's not actually a speed bump at all when approached from the correct direction.
The ramp could be long enough such that the vehicle's rear wheel would depress the spring during and after the front wheel had rolled off (thus not springing back underneath your vehicle). Or alternatively, the top of the ramp could be lower than the typical height of a car's undercarriage.-- xaviergisz, Aug 11 2009 Ooh, a see-saw speed bump (about 10m long and 20cm high).
If you go over it too fast you jump off the end, but if you go at the correct speed it is hardly a bump at all, more of a hillock. The 'correct' speed would be determined by a damper.
It would also have the added benefit of forcing cars to leave a safe distance in front to allow time for it to reset.-- marklar, Aug 11 2009 Completely baked, a car park near me when I was young had 2 staggered rows of weighted metal flaps about 1 foot square, which were at 45 degress when up. A car driving out pressed them down with it's tyres with a series of satisfying 'clunks' as the counterweights popped them back up (less satisfying noise for drivers of low slung sports cars!).-- pocmloc, Aug 11 2009 The satisfaction derived from driving a large, powerful tracked vehicle the wrong way over one of those "severe tyre damage" strips , completely crushing and mangling it beyond repair, has to be experienced to be believed, particularly when a legitimate reason to do so exists, such as "Well, you said put it in the car park, and these things don't have much of a turning circle, we can't park it on the road, and you did invite us here anyway .... next time we'll just go straight through the fence...."-- 8th of 7, Aug 11 2009 What kind of tracked vehicles 'don't have much of a turning circle' ?-- Twizz, Aug 11 2009 Most armoured fighting vehicles have difficulty executing sharp turns at low speed; it can cause track damage. That's because the their tracks are of a very different suspension design from those on civilian equipment like earthmovers, which are designed for very low speed operation.-- 8th of 7, Aug 11 2009 what [pocmloc] said: baked.-- FlyingToaster, Aug 11 2009 Quite baked, as others have said, but I'd like to point on the error in terminology. As described, this is not a one-way speed bump, but a one-way barrier.
Just giving it some cursory thought, it seems that it might be quite difficult to slow, but not stop, only one direction of travel on a road that allows movement in both directions.-- tatterdemalion, Aug 11 2009 I won't bother to link to it - just check out the long line at the top of the page.-- normzone, Aug 12 2009 random, halfbakery