Side Underride Crashes Kill Hundreds of Americans Every Year — Inside the 2026 Bill That Could Finally Require the Guards That Stop Them
There is a particular kind of truck crash that safety advocates call “the silent killer.” It is the underride crash — a collision in which a passenger vehicle slides underneath the body of a large truck or trailer. Because the point of impact is above the car’s bumper, hood, and engine — the structures designed to absorb a crash — the trailer instead strikes the passenger compartment directly. The roof and upper body of the car can be sheared away. Underride crashes are not merely severe; they are frequently and gruesomely fatal, even at moderate speeds.
In February 2026, members of Congress reintroduced the Stop Underrides Act — a bill that would, for the first time, require side underride guards on newly built trailers and large trucks. Federal regulations already require rear underride guards, but there is currently no federal requirement for side or front underride protection at all — a gap that safety researchers estimate costs hundreds of lives every year.
This guide explains what underride crashes are and why they are so deadly, what the 2026 Stop Underrides Act would actually change, and — for the families who have already lost someone — who can be held legally responsible when an underride crash happens, even before any new law takes effect.
What Underride Crashes Are — and Why They Are So Deadly
What happens: In an underride crash, a passenger vehicle travels beneath a truck trailer — from the rear or, more often fatally, from the side. The trailer bypasses the car’s crumple zones and strikes the windshield and roofline, intruding directly into the space occupied by the people inside.
The toll: Safety researchers and the Stop Underrides Act’s sponsors estimate that underride crashes kill more than 300 people in the United States every year — and many experts believe the true number is higher, because underride is often not separately recorded in crash data.
Current law: Following a mandate in the 2021 Bipartisan Infrastructure Law, federal standards FMVSS 223 and 224 were upgraded to strengthen rear underride guard requirements; the updated rear-guard rule took effect in January 2023.
The gap: There is no federal requirement for side underride guards, and none for front underride protection. The most lethal underride configuration — a vehicle striking the side of a long trailer — is the one current regulation does not address.
The Stop Underrides Act 2.0 — What the 2026 Bill Would Do
The Stop Underrides Act has been introduced in Congress before, and in February 2026 it was reintroduced in an updated form. The bill directs the Department of Transportation to finalize a rule — within 18 months — requiring side underride guards on newly manufactured trailers, semitrailers, and single-unit trucks. It would also direct continued work on rear and front underride protection. As of early 2026, the legislation has been referred to the Senate Committee on Commerce, Science, and Transportation and to the House Committee on Transportation and Infrastructure.
The trucking and trailer-manufacturing industries have opposed a side-guard mandate, citing cost and weight. The National Highway Traffic Safety Administration has estimated that side underride equipment could add roughly $3,740 or more per trailer, along with 450 to 800 pounds of additional weight that slightly reduces cargo capacity and fuel economy. Supporters respond that crash testing — including testing by the Insurance Institute for Highway Safety — has repeatedly shown that side underride guards work, preventing the catastrophic passenger-compartment intrusion that makes these crashes lethal. The core question before Congress is whether a few thousand dollars per trailer is worth several hundred lives a year.
Who Is Responsible When an Underride Crash Happens
A grieving family often hears a discouraging message after an underride crash: that because the trailer met current federal standards — or because no side-guard rule yet exists — nothing can be done. That is not how the law works. The absence of a federal mandate does not give a trailer manufacturer immunity from responsibility for a foreseeable, preventable, and well-documented hazard.
Liability after an underride crash can extend to several parties. The trailer manufacturer may be responsible if the trailer was defectively designed — including a design that omitted a feasible, proven safety device like a side guard. The motor carrier may be responsible for operating a trailer with missing, damaged, corroded, or improperly maintained underride guards. The truck driver and the broker that arranged the load may bear responsibility for the conduct that caused the collision itself. Each of these is a separate avenue of accountability, and a properly investigated case examines all of them.
Why “There Is No Federal Requirement” Is Not a Complete Defense
Texas product liability law does not require a federal regulation before a manufacturer can be held accountable for a dangerous design. A product can be defective — and a manufacturer can be liable — when there was a reasonable, feasible alternative design that would have prevented the harm, and the manufacturer chose not to adopt it. Side underride guards are not theoretical. They have been designed, built, crash-tested, and proven effective. When a trailer manufacturer sells a trailer without that protection, and a person is killed in exactly the manner the guard would have prevented, the question for a jury is whether that omission was reasonable.
Compliance with a minimum federal standard is evidence a manufacturer will point to, but it is not a shield. Minimum standards are floors, not ceilings, and the law has long recognized that a manufacturer can meet every applicable regulation and still have built an unreasonably dangerous product. The fact that Congress is actively moving to mandate side guards only underscores what safety researchers have known for years: the technology exists, it works, and its absence is a choice.
What Families Should Know About Underride Crashes
- Rear guards are required; side and front guards are not. Federal rules strengthened rear underride guard standards in 2023, but impose no requirement for side underride protection — the most lethal configuration — or for front underride guards.
- The Stop Underrides Act 2.0 would close the gap. The bill reintroduced in February 2026 would require side underride guards on new trailers within 18 months of a final rule, but it is not yet law.
- A manufacturer can be liable even without a mandate. Texas product liability law allows recovery when a feasible alternative design — like a proven side guard — would have prevented the death. Meeting a minimum federal standard is not a complete defense.
- These deaths are preventable. Crash testing has repeatedly shown that side underride guards stop the passenger-compartment intrusion that makes underride crashes fatal. An underride death is, in most cases, an engineered-out outcome that was not engineered out.
Your Rights After a Truck Underride Crash
If you have lost a family member in an underride crash, or survived one with catastrophic injuries, the most important thing to understand is that “the trailer was legal” is not the end of the conversation. It is the beginning of an investigation. The questions that matter are whether the trailer could and should have been equipped with side underride protection, whether its existing rear guard was sound and properly maintained, and what caused the underlying collision in the first place.
Evidence in these cases disappears quickly. The trailer is repaired, returned to service, or scrapped. Maintenance and inspection records for the underride guards can be lost. The physical relationship between the vehicles — the crush patterns that prove an underride occurred and show how it happened — needs to be documented by qualified experts before the vehicles are moved or destroyed. Preserving evidence early is one of the most important steps a family can take, and it generally requires an attorney acting quickly.
Underride cases are technical. They involve trailer design, materials engineering, crash reconstruction, and biomechanics, and they are defended aggressively by manufacturers and their insurers. They also frequently involve catastrophic outcomes — wrongful death, traumatic brain injury, paralysis — and the recoveries available must account for a lifetime of loss. These are not cases to be handled casually or settled early without a full understanding of what happened and what protection was available but absent.
Our Texas truck accident attorneys investigate the full chain of responsibility in a truck crash — the driver, the carrier, the broker, and the manufacturer of the trailer itself. If an underride crash has taken someone you love, you deserve a complete and honest accounting of whether that death could have been prevented.
Your Future. Our Fight.
McFarlane Law represents the victims of catastrophic truck crashes and their families across Texas and the Permian Basin, including the families of those killed in underride collisions. We investigate quickly, preserve the physical evidence before it disappears, and hold every responsible party accountable — drivers, carriers, brokers, and trailer manufacturers. Every case is handled on a pure contingency basis — you pay nothing unless we win.
No fee unless we win. Available 24/7. Offices in Austin & Odessa.
Zach McFarlane
Zach McFarlane is a Texas trial attorney and the founder of McFarlane Law. He represents injured workers, families, and accident victims across Texas — from Austin and Houston to the Permian Basin — in catastrophic personal injury, oilfield, maritime, trucking, and wrongful death cases. The firm has helped clients recover more than $100 million in verdicts and settlements.
View Full Profile →
