Or just get hydrolics on one side of your car and when going toward them CLICK the button and wheely through them .LMAO, thats great.Surely someone with half a brain cell would wait untill a bus went over them then see how fast they come back up.
Think it either works buy a code you enter onto a panel or by a weight sensor buried in the road.Made me laugh - I've never seen them thougrh (I'd heard they were coming mind).
Absolutely classic though - the stupid things people will try 
What happens if someone who's allowed in tries to take a trailer tho that sees daylight?? Is that how it works??