People are getting killed by drunk, criminal, crazy and senile drivers entering motorways, freeways, autobahns by the exit ramps and driving into oncoming traffic against the flow. It's usually the police officers who try to stop these people who become casualtys.
What if the exit ramp from the freeway/motorway only allowed traffic to flow in one direction over it by installing a device like a very long cattle grid at the top of it which had rollers embedded in it. The rollers would be designed so that they would not move if a vehicle passed over them in the correct direction to exit the freeway but would spin if someone drove over them in the wrong direction trapping their car at that point. Perhaps they could have stingers embedded on the undersides of the rollers to puncture the tyres.
Sure, a smart criminal could figure a way around this trap but the drunk, crazy or senile driver would be stopped at the rollers before they caused a major pile up.
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What if a person applied the brakes on these rollers?
Seems to me the same rotation that prevents a car from going the wrong direction would also prevent it from stopping.
I agree, applying the brakes when you were driving in the correct direction over the rollers is an obvious design flaw in a ratchet based roller system which allows rotation in one direction but not the other, and undoubtedly people would apply the brakes while travelling on the rollers which would result in accidents.The design would have to be modified to take this into account which would add to the complexity and the cost.
I think that a criminal could also apply the brakes when he was driving in the wrong direction which would lock the rollers against their ratchets and allow him to skid across the trap if he was going fast enough which is why the trap would need to span a large distance on the exit ramp
There is also the case where two cars are on the rollers at the same time, one is going in the correct direction and the other is going in the illegal direction and the legal car locks the roller its drive wheels are on which could assist the illegal car but you could counter this by having each roller being made up from individual wheels on the spindle so the direction control mechanism (aside from the design flaws mentioned above) would still work correctly for each car.
It's a tricky problem to solve and the idea needs a bit more work.
The other problem I thought about with putting stingers on the undersides of the rollers to puncture the illegal drivers tyres is: "Would the non powered wheels on the legal car drag the rollers round as they passed over them to expose the stingers just in time for the guy behind you to drive over them?"
Instead of rollers, install the same one-way device auto rental agencies use at airports (in the US - metal blades/spikes that fold into the pavement if you're headed the right direction, or puncture your tires if headed the wrong direction). These could be connected to a motion sensor that deploy only when the sensor detects a driver headed for disaster. Or forget the spikes and have the sensor drop a gate...or fire a surface-to-car missile and eliminate the problem driver for ever (just kidding!!...that would simply cause more traffic delays!!). .
I like the fold in spikes idea, think that would work much better than a roller/ratchet based system which would need a more complex design and engineering, if the spikes folded into the exit ramp when someone drove over them in the correct direction then returned (sprung) back to the deployed position when the legal driver had passed and remained deployed and angled to stop an illegal driver headed in the wrong direction that would solve the problem.I think you have provided a solution to this one..
It's generally a bad idea to disable a vehicle. A driver can't control a damaged vehicle, which increases the chance of an accident, and there's always the chance that the driver who drove over this device may have noticed what he was doing and avoided a crash. If you disable the car, the driver no longer has this ability.
Actually the stingers that the police use now are designed to deflate the vehicles tyres without shredding them and the driver can stop the vehicle under control, use these type of stingers on the exit ramp device.
How much control does someone who is attempting to drive the wrong way down a freeway or motorway have? much better to stop them on the exit ramp before they drive the wrong way into a traffic flow and cause a 100 car pile up.
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http://news.bbc.co.uk/1/hi/england/manchester/4475332.stm
I drove over some of these uni-directional spike strips at the Albert dock car park in Liverpool yesterday, the spikes get pushed in to the road when your car goes over them in the correct direction and lock in the deployed position to shred the tyres when you drive the wrong way. It would be very easy to put a beefed up versison of this simple technology at the bottom of the motorway exit ramp.....