Beware of this Subtle Road Hazard

[fahrvergnugen]

I found this video while looking at some crazy car crash compilations.   Pretty scary.  But I also found a couple more cases where this was captured that were similar in result.  One of those caused the car to jump and roll into the center barrier wall.

 

I think the physics behind this is that a tire rolling down the road has the back edge going upwards as it rolls.  When a car’s bumper hits it it acts like a brake trying to stop the tire from rolling which also causes the tire’s friction with the road to increase.  The net result is to cause the bumper to go upwards, and then the tire starts to wedge it’s way under the bumper making the problem worse.  The tire is strong enough to carry the weight of a car and as it goes further underneath the car must go airborne to get over it.  

 

The problem might be less severe if the car’s bumper touches the tire BELOW the center of the tire, which would force the tire upward over the car.  Then you have the risk of that tire/wheel (weighing maybe 100 lbs) to crash into your windshield.

 

Bottom line,  if you EVER get into this situation, immediately jam on the brakes as hard as you can.  This pushes the nose down to reduce the case of the tire going under you and reduces the impact speed.  You then risk being rammed by the car behind you, but that is less risky than a total flip and roll incident.  When cars roll of flip the sudden inertial effects on your internal organs can be fatal, even if you are not otherwise harmed.  The last thing I would ever want to experience is a roll or flip.

 

Pretty weird shit going on out there.