The Deadly Engineering Flaw Missing from Almost Every Commercial Trailer
If you look at the rear of any commercial 18-wheeler, you will see a heavy steel bar hanging down below the trailer doors. This is a rear underride guard (often called a DOT bumper or Mansfield bar). It is legally mandated and designed for one horrific purpose: to prevent a passenger car from sliding completely underneath the trailer during a rear-end collision, which would sheer off the car's roof and instantly decapitate the occupants.
However, if you look at the sides of that exact same 53-foot trailer, you will likely see nothing but empty space between the front and rear wheels. This massive gap sits at the exact height of a passenger car's windshield. When a truck driver illegally pulls out across a dark highway, or violently swings across lanes, cars easily slide under the side of the trailer. Exposing the deadly engineering flaw missing from almost every commercial trailer—the lack of side underride guards—is one of the most critical safety battles in modern trucking litigation.
Side underride guards are lightweight, energy-absorbing metal panels that bolt onto the sides of a trailer. Crash tests conducted by the Insurance Institute for Highway Safety (IIHS) have definitively proven that these guards successfully deflect passenger cars at high speeds, allowing the car's airbags and crumple zones to deploy normally, saving the occupants' lives. The technology exists, it works, and it is relatively inexpensive.
Why the Industry Refuses to Adapt
Despite decades of horrific fatalities and relentless pressure from safety advocates, the trucking industry continues to lobby heavily against federal mandates requiring side underride guards. When an attorney litigates a side-underride crash, they must expose the industry's choice to prioritize profits over human lives:
Trucking corporations argue that bolting steel guards to the side of a trailer adds roughly 500 pounds to the vehicle's total weight. Because federal law caps commercial trucks at 80,000 pounds, adding 500 pounds of safety equipment means the company has to haul 500 pounds less freight per trip. In litigation, this proves the company calculated that a human life was worth less than the revenue of 500 pounds of cargo.
Defense lawyers will also argue that side guards hang too low and could cause the truck to get "high-centered" (stuck) on steep railroad crossings or angled loading docks. However, engineers have already developed retractable and high-clearance guards that solve this issue completely. The refusal to adopt them is purely financial, not practical.
In some jurisdictions, attorneys don't just sue the negligent truck driver; they file a "Product Liability" lawsuit against the multi-billion dollar corporation that manufactured the trailer (such as Wabash or Great Dane). They argue that selling a massive highway trailer without side guards is legally equivalent to selling a defective, unreasonably dangerous product.
Fighting for Change Through Litigation
Because the federal government has historically been slow to mandate side underride guards, the only way to force the trucking industry to adopt this lifesaving technology is through massive civil verdicts. When juries punish motor carriers with multi-million dollar punitive damages for refusing to install a $2,000 piece of safety steel, it forces the entire industry to rethink its deadly financial calculus.