Why Are 18-Wheeler Safety Bars Called 'Mansfield Bars'?

LOUISIANA - Most of us have driven behind an 18-wheeler and noticed the thick metal bar mounted underneath the rear of the trailer. It's easy to overlook, but that piece of steel has saved countless lives over the years.

Known as the Mansfield Bar, this important safety feature written into law carries a name tied to one of the most heartbreaking highway tragedies in Louisiana history.

Here's why every 18-wheeler on the road has one today.

The Louisiana Crash That Changed Truck Safety Forever

The Mansfield Bar gets its name from actress Jayne Mansfield, whose tragic death helped spark major changes in highway safety.

Jayne Mansfield Car Crash — (Photo by Keystone/Hulton Archive/Getty Images)

In the early morning hours of June 29, 1967, Mansfield was traveling through Southeast Louisiana after a nightclub appearance in Biloxi, Mississippi. She was headed toward New Orleans for a scheduled television interview when disaster struck.

Authorities said the car she was riding in collided with the rear of a tractor-trailer on U.S. Highway 90 in Slidell, Louisiana after traffic slowed because of a mosquito-spraying truck operating ahead. The vehicle slid underneath the trailer, killing Mansfield, her attorney Samuel S. Brody, and the driver instantly. Her three young children, who were asleep in the back seat, survived with injuries.

From history.com -

Blonde bombshell and celebrated actress Jayne Mansfield is killed instantly on June 29, 1967, when the car in which she is riding strikes the rear of a trailer truck on U.S. Route 90 East of New Orleans, Louisiana.
On a dark stretch of road, just as the truck was approaching a machine emitting a thick white fog used to spray mosquitoes (which may have obscured it from Harrison’s view), the Electra hit the trailer-truck from behind.

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How The Crash Led To Safer Highways

The Mansfield Bar gets its name from actress Jayne Mansfield, whose tragic death helped spark major changes in highway safety. Public pressure following the fatal Louisiana accident prompted federal officials to strengthen safety requirements for commercial trailers.

Rear underride guards eventually became mandatory on newly manufactured trailers, dramatically reducing the chances of passenger vehicles sliding underneath the back of an 18-wheeler during a collision.

Even though the official name is "rear underride guard," truckers, mechanics, and many motorists still commonly refer to them as Mansfield Bars.

The next time you're driving behind a semi, take a look beneath the trailer. That heavy steel bar represents decades of safety improvements and serves as a reminder that many of today's vehicle safety standards were written after tragic events.

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Gallery Credit: Michael Dot Scott