What Are The Bars On The Back Of A Semi Called

What Is A Mansfield Bar On A Truck

The horizontal bar hanging low across the back of a semi-trailer is commonly known as a Mansfield bar. Officially, it’s called a rear underride guard, sometimes a rear impact guard or ICC bumper, but “Mansfield bar” is the widely adopted term.

The reason the bar exists at all comes down to basic physics. A passenger car’s bumper and crumple zones sit low to the ground, built to absorb impact around that height. The back of a trailer, without a guard, sits well above that, so in a rear-end collision the car can slide straight underneath it, and the trailer bed ends up hitting the windshield and roof instead of the bumper. That’s an underride crash, one of the most dangerous ways to be hit by a truck.

Federal regulations now set minimum standards for how strong these guards have to be and where they sit on the trailer. But standards on paper don’t always match what’s actually installed and maintained. In a lot of underride crashes, the guard turns out to have been missing, rusted through, mounted wrong, or just not strong enough to do its job.

If you or someone you love was hurt in a crash where a vehicle went underneath a trailer, the condition of that guard, or the fact that there wasn’t one, can be critical evidence. A truck accident lawyer can look into whether the trailer met federal safety standards.