I'm watching a show called Crash Science, and they're talking about concrete median barriers. Wow I had no idea there was so much engineering that goes in them. So I looked it up on the net, some of you may find this interesting . .
For the more common shallow-angle hits, the NJ-shape is intended to minimize sheet metal damage by allowing the vehicle tires to ride up on the lower sloped face . . . It is only necessary to lift the vehicle enough to reduce the friction between the tires and the paved surface. This aides in banking and redirecting the vehicle. If the vehicle is lifted too high into the air, it may yaw, pitch, or roll, which can cause the vehicle to roll over when the wheels come in contact with the ground again.