I have read many news reports of truck crashes. It often strikes me how little the media, along with everyone else, understands the underride problem. Last night I read an article about a truck crash which happened in November in Dallas; it was a good example of this common misunderstanding of what an underride is.
A car was traveling northbound along Harry Hines Boulevard when it started coming up on a UPS truck at the Lombardy Lane stoplight. The 18-wheeler’s 53-foot trailer was empty at the time. However, the car’s driver did not stop and slammed into the back of the big rig. The UPS truck’s rear bumper broke as the car went underneath the trailer. http://dfw.cbslocal.com/2017/11/13/car-slams-into-big-rig-dallas/
What the reporter apparently misunderstood was that the rear bumper did not break off as the car went underneath the trailer. No, the car went underneath the trailer because the bumper broke off!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! It was too weak — just like on the majority of the millions of trucks on the road today. Underride tragedies waiting to happen.
At first I was frustrated with the way underride gets reported (or rather does not get reported). But then I realized that this is a perfect example of the common misperception that something about the severity of the crash forces/dynamics itself is what leads to the car knocking off or bending the rear underride guard. In fact, it is the weak guard which gives way, fails, and bends or comes right off the trailer and then there is nothing to stop the car from going into the empty space under the truck.
Or, as Jerry Karth says, to put it another way, “the guard failed to perform as it was designed to do.” (As this IIHS video so thoroughly explains.)
In contrast, see what happens when there is an effective underride protective device to cause the car to bounce off the guard (deflects the crash forces) and allows the car’s crush zone, airbags, and seat belts to work like they were supposed to upon collision.
Improved Rear Underride Guard Crash Test:
Side Guard Crash Test:
The car is damaged, but the passengers are safe:
I hope this helps people to better understand the dynamics of an underride crash.
