Underride Truck Accidents: The Deadliest Crash on the Highway
An underride accident occurs when a passenger vehicle slides beneath the trailer of a semi truck, either from behind (rear underride) or from the side (side underride). Because the trailer bed sits at windshield height, these crashes defeat every safety system a car has — crumple zones, airbags, seat belts — and cause a disproportionate share of truck crash fatalities. Survivors and families of victims have powerful legal claims, often against multiple parties.
Rear vs. Side Underride Crashes
Rear underride typically happens when a truck stops suddenly, drives far below the speed of traffic, or is parked on a shoulder without proper warning triangles and lighting. Federal law (49 CFR §393.86) requires rear impact guards — often called Mansfield bars — on most trailers, and the NHTSA strengthened rear guard standards in 2022.
Side underride commonly occurs at night or in poor visibility when a truck crosses or turns across traffic and a car strikes the trailer broadside. The IIHS has petitioned for mandatory side underride guards for years; most U.S. trailers still lack them. That regulatory gap is central to many liability theories against carriers and trailer manufacturers.
Who Can Be Held Liable?
Potential defendants include the truck driver (unsafe stopping, missing reflective triangles, dirty or inoperative marker lights), the motor carrier (poor maintenance of underride guards, conspicuity tape violations), the trailer manufacturer (defective or absent guards under product liability law), and even a shipper or broker in some circumstances.
FMCSA regulations require reflective sheeting and functioning lamps on trailers precisely because underride crashes so often involve a driver who never saw the trailer in time. Roadside inspection histories and CSA violation data frequently show a pattern of ignored conspicuity and lighting defects.
Compensation in Underride Cases
Underride collisions cause decapitation-level trauma, traumatic brain injury, facial and cervical spine injuries, and a high rate of wrongful death. Families may pursue wrongful death and survival actions recovering medical and funeral expenses, lost financial support, and loss of companionship.
Because defective-guard claims implicate manufacturers as well as carriers, total available insurance often far exceeds the trucking policy alone. An experienced truck accident attorney will pursue every layer of coverage, including excess and umbrella policies.
Frequently Asked Questions
What is a Mansfield bar?
It's the common name for the rear impact guard required on trailers, named after actress Jayne Mansfield, who died in a 1967 rear underride crash. If a guard was missing, rusted, improperly repaired, or failed on impact, both the carrier and the trailer manufacturer may be liable.
The truck was parked — do I still have a case?
Possibly, yes. Federal rules require drivers stopped on a highway or shoulder to deploy warning triangles or flares within 10 minutes. A truck parked at night with no warnings and inadequate reflective tape is a classic underride liability scenario.
How long do I have to file an underride claim?
Statutes of limitations range from one to four years depending on the state and whether the claim is for injury or wrongful death. Product liability claims against trailer manufacturers may have different deadlines. Speak with an attorney promptly to protect the evidence and the claim.