Drivers are just realizing the reason why semis have bars behind back tires

A TRAVELING musician has revealed the safety hazard that a semi truck's back tire bars prevent — and this security feature's history runs deeper than you may imagine.

We the Kings Bassist Charles Trippy unveiled the fast fact in a Facebook video posted to his account.

Charles’ (@CharlesAndAllie) video clip starts with him saying that actress Jayne Mansfield crashed her car into the back of a semi-truck in the 1960s.

He added that Mansfield suffered severe head trauma and died from the crash since her car went directly under the semi-truck that didn't have safety bars.

Charles clarified that these safety bars stop cars from driving underneath semi-trucks, decreasing driver fatality risk.

The technical term for the safety bars is D.O.T. (Department of Transportation) bumpers.

His wife, who was driving the car, initially thought it was a step to help commercial truck drivers load cargo.

But Charles stated that there's an exception to this safety bar rule.

The rockstar said that commercial trucks with wheels further back don't need this safety bar since another driver hitting their rear would make contact with the wheels and stop.

Many reports had stated that Mansfield was decapitated when she died in her June 29, 1967 car accident.

The actress’ police report on the accident stated that she had the upper portion of her head severed, according to Snopes.

The death certificate also stated Mansfield had a crushed skull with forcible separation or detachment of cranium and brain tissue.

One viewer commented on Charles’ Facebook video: "Those ‘bars’ are also used to lock a trailer to a dock so safe unloading/loading can happen without trailer creep."