Trucking Side Guards Could Save Lives

When a car strikes the side of a trailer at highway speed, the consequences can be devastating. The hood crumples, the windshield shatters, and the entire vehicle slides beneath the trailer. In a matter of seconds, the passenger compartment is sheared away. These are known as side underride accidents, and they are among the most devastating—and preventable—collisions on the road. Our Colorado truck accident attorneys prepared this article to talk about measures that could save lives.

What Are Side Guards?

“Side guards” are physical barriers mounted along the lower sides of trailers, usually between the rear axles and the landing gear. Side guards are designed to prevent smaller vehicles, cyclists, or pedestrians from sliding underneath a trailer in a side-impact collision.

The guards can be rigid (solid steel or aluminum barriers) or energy-absorbing, designed to deform on impact and dissipate force. Both styles protect passenger vehicles from catastrophic underride, keeping the vehicle outside the trailer’s deadly undercarriage zone.

Side guards are not new technology. The European Union, Japan, Brazil, and the United Kingdom already mandate them. In London, for example, side guards have been standard since the 1980s—largely to protect cyclists and pedestrians. The European Commission estimates these systems have reduced side underride fatalities by up to 60%.

In contrast, the United States has only required rear underride guards since 1998. Despite strong data and growing public pressure, side protection remains optional. It is one of those uniquely American policy paradoxes: we have the technology, we have the proof, and yet we are still debating whether safety is worth the investment.

Mandating Side Underride Guards

The National Highway Traffic Safety Administration is considering a proposal that would mandate side underride guards on large trailers. The proposal is in the Advance Notice of Proposed Rulemaking (“ANPRM”) stage. It would require:

• Rigid or energy-absorbing barriers mounted between the trailer’s axles and landing gear;
• Certification standards similar to rear underride guards (already mandated);
• Possible retrofit requirements for newer fleets within a certain model year range.

The NHTSA first began studying side guards decades ago, but progress has been painfully slow. The agency’s most recent ANPRM, published in 2023, asked for new data, cost estimates, and industry feedback. Since then, the rulemaking process has been stuck in the “analyzing comments” phase—a bureaucratic holding pattern that has now been pushed to January 2026 for further review.

Safety groups argue side guards could save hundreds of lives per year and significantly reduce fatality rates in truck accidents. The trucking industry, however, has raised legitimate concerns:

• Weight and fuel efficiency: Side guards can add several hundred pounds per trailer, reducing payload capacity and increasing fuel burn;
• Cost: Outfitting a large fleet could cost thousands of dollars per trailer;
• Data: The industry says crash data doesn’t yet show a clear cost-benefit ratio for mandatory installation.

There’s also a legal dimension to this debate that often gets overlooked. In wrongful death or personal injury cases, the absence of a regulatory standard complicates accountability. If side guards are not required, defense lawyers can argue a trucking company “followed all applicable laws.” This is true even if the result was a preventable death. Jurors, who are often unaware that side guards exist at all, struggle to assign blame in a vacuum of regulation.

But when a safety rule does exist, the analysis becomes simple. If a carrier ignores a side-guard requirement and someone dies, liability is clear. The existence of a mandate creates a standard of care—a line between negligence and compliance that juries can easily understand. Regulations, in that sense, do not just save lives. They also make justice more consistent and fair.

Until the NHTSA finishes analyzing the comments and testing data, the rule remains in limbo.

Bowman Law: Colorado Truck Accident Attorneys

From my perspective as a Colorado truck accident lawyer, side guards represent the next logical step in highway safety—just like seat belts, airbags, and rear underride bars once did.

When those technologies were introduced, industries complained about cost, weight, and complexity. Today, no one questions their necessity. The same will be true of side guards.

Their benefits go beyond crash prevention. They create transparency, accountability, and standardization. They give juries clarity and victims justice. And most importantly, they save lives—lives that can never be replaced once lost to a preventable design flaw.

Unfortunately, we will not see any new rules enacted until at least 2026. This delay is not due to lack of evidence. There is a delay due to pressure. Major freight and trailer lobbies argue that mandating side guards would be too expensive, too heavy, and not justified by the available crash data.

Moving forward, the trucking industry will continue to talk about cost-per-pound and marginal fuel efficiency. But we should be talking about human value. We should be talking about the cost of inaction. Every life lost in a side underride crash is one too many, and every year without a mandate is another missed opportunity to make our roads safer.

As a Colorado truck accident attorney who has seen the aftermath of these collisions firsthand, I can say this with certainty: no trucker, no company, and no regulator ever wants to face another family whose loved one died in a crash that could have been prevented by a $3,000 piece of metal.

The Colorado truck accident attorneys at Bowman Law have the experience and resources to go after truckers for negligence. We have built a reputation in trucking cases by combining deep knowledge of FMCSA regulations, skilled accident reconstruction, and relentless advocacy for our clients. At Bowman Law, we do not just handle cases — we build them to withstand the most aggressive defense strategies.

If you were injured in Colorado truck accident, you deserve a law firm with a proven record of success. Please send us a message or call us at 720-526-0298 to schedule a free case evaluation. With Bowman Law on your side, you gain a team of Colorado truck accident lawyers who will fight to protect your rights, secure the compensation you need, and deliver the justice you deserve. We serve clients across Colorado’s Front Range and beyond, including Denver, Colorado Springs, Boulder, Fort Collins, Westminster, Lakewood, and Aurora.