Truck Underride Accidents

The Bottom Line

Truck underride crashes are among the most catastrophic accidents on the road, with fatality rates far exceeding those of other collision types. Current federal safety standards only require rear underride guards -- and those guards are built to a standard that fails in many real-world crashes. There is no federal requirement for side underride guards. Multiple parties may be liable, including the truck driver, trucking company, trailer manufacturer, and guard manufacturer. If you or a family member has been involved in an underride crash, legal representation is not optional -- it is essential.

How Underride Crashes Happen

Underride crashes occur in three primary configurations, each with distinct mechanics and risk factors.

Rear Underride

Rear underride is the most recognized form. It occurs when a passenger vehicle strikes the back of a trailer or semitrailer and slides underneath. Common scenarios include:

• A truck stopped or moving slowly on a highway -- the speed differential between the car and truck is the primary danger
• A truck pulling onto a road from a side street -- the car strikes the rear of the trailer before the truck has fully accelerated
• Poor visibility conditions -- at night, in fog, or in rain, a trailer's rear may be nearly invisible if reflective markings or lights are inadequate

Side Underride

Side underride crashes happen when a vehicle strikes the side of a trailer -- typically when a truck crosses an intersection, makes a turn, or changes lanes. The gap between a trailer's rear axles and the landing gear near the cab leaves a long, unprotected expanse along the side of the trailer.

Side underride crashes are particularly dangerous because:

• The side of a trailer has no federally mandated guard -- there is nothing to prevent a vehicle from sliding underneath
• Trucks crossing intersections are vulnerable -- a car traveling at speed can strike the trailer broadside
• Lane-change collisions -- when a truck moves into an adjacent lane, a car beside it can be swept underneath

Front Override

Front override -- sometimes called "override" rather than "underride" -- occurs when the front of a large truck rides up and over a smaller vehicle. Because truck cabs sit high off the ground, the truck's bumper and grill can pass over the hood of a passenger car and strike the windshield and roof directly.

Front override crashes most commonly occur when:

• A truck rear-ends a passenger vehicle -- the truck's front end rides over the car's trunk and rear passenger compartment
• A truck fails to stop at an intersection -- the cab overrides the side of a passenger vehicle

Why Underride Crashes Are So Deadly

Underride crashes have a disproportionately high fatality rate because they bypass every safety system designed to protect vehicle occupants.

Roof shearing. In a severe underride crash, the bottom edge of the trailer acts like a blade against the car's windshield and roof. The roof structure -- which is designed to handle rollover forces pressing down from above -- is not engineered to resist a horizontal shearing force from a trailer edge. In many underride crashes, the entire passenger compartment above the dashboard is destroyed.

Airbags do not deploy effectively. Modern vehicle airbags are triggered by sensors that detect a frontal or side collision with the vehicle's structure. In an underride crash, the car's front end passes under the trailer without engaging the structural members that trigger airbag deployment. Even when airbags deploy, they offer little protection against a trailer edge striking at roof height.

Crumple zones are bypassed. A vehicle's crumple zones are designed to absorb collision energy through controlled deformation of the front or rear of the car. When the car slides under the trailer, the crumple zones never engage -- the collision energy is transferred directly to the passenger compartment.

Survival rates are low. Because the collision forces bypass the vehicle's protective systems and directly impact the occupant space, underride crashes are far more likely to be fatal than other types of truck-involved collisions. When occupants survive, injuries are typically catastrophic -- traumatic brain injury, spinal cord damage, severe facial and skull fractures, and traumatic amputations.

Current Federal Safety Standards

Federal underride regulations have not kept pace with the severity of the problem.

FMVSS 223 and 224: Rear Underride Guards

The Federal Motor Vehicle Safety Standards (FMVSS) 223 and 224, administered by NHTSA, establish requirements for rear underride guards on trailers:

• FMVSS 223 sets the strength requirements for rear impact guards
• FMVSS 224 requires that rear impact guards be installed on new trailers manufactured after January 26, 1998

However, the current standard has significant limitations:

• The guard only needs to withstand a 30% overlap crash at 35 mph. Many real-world rear underride crashes involve higher speeds, full-width impacts, or offset impacts that exceed the guard's design parameters.
• The standard was last meaningfully updated decades ago. Vehicle speeds and traffic patterns have changed, but the guard standard has not.
• Older trailers are grandfathered in. Trailers manufactured before 1998 may have weaker guards or no guards at all, and there is no retrofit requirement.
• Maintenance and inspection requirements are limited. Guards that are damaged, corroded, or improperly reattached after repair may not function as intended.

No Federal Side Guard Requirement

There is currently no federal requirement for side underride guards on trailers in the United States. This is a significant regulatory gap. Side underride crashes are deadly, and IIHS testing has shown that side guards can prevent passenger vehicles from sliding underneath trailers.

Several countries -- including the European Union, Japan, and Brazil -- require some form of side underride protection on trailers.

No Federal Front Guard Requirement

There is also no federal requirement for front override guards (also called front underride guards) on truck cabs. While some manufacturers have begun voluntarily installing improved front bumper designs, there is no regulatory standard.

The Stop Underrides Act

The Stop Underrides Act is bipartisan federal legislation that has been introduced in Congress multiple times. The bill would address the gaps in current federal standards:

• Require side underride guards on new trailers. This is the most significant provision -- it would close the regulatory gap that leaves the sides of trailers completely unprotected.
• Strengthen rear guard standards. The bill would update FMVSS 223 to require guards that withstand full-width crashes at higher speeds, reflecting real-world conditions.
• Require front override guards on truck tractors. This would address front override crashes where the cab of a truck rides over a smaller vehicle.
• Mandate a comprehensive study of underride crashes. Better data collection would improve understanding of how many underride crashes actually occur.

The bill has bipartisan support and has been championed by safety advocates, families of underride crash victims, and organizations including IIHS. The trucking industry has generally opposed mandatory side guard requirements, citing cost and weight concerns. As of early 2026, the Stop Underrides Act has not been signed into law.

Who Is Liable in a NC Underride Accident

Underride accidents often involve multiple liable parties, each with a distinct legal theory of liability.

The Truck Driver

The truck driver may be liable for negligent driving that caused or contributed to the crash. This includes:

• Stopping or traveling at an unsafe speed on a highway
• Failing to use hazard lights or reflective triangles when stopped
• Making an unsafe lane change or turn
• Violating hours-of-service regulations and driving while fatigued
• Operating without adequate lighting or reflective markings

The Trucking Company

The trucking company (motor carrier) may be liable under several theories:

• Respondeat superior -- employer liability for the driver's negligent acts while on the job
• Negligent hiring or retention -- if the company hired or retained a driver with a poor safety record
• Negligent maintenance -- if the company failed to maintain the underride guard, trailer lighting, or reflective markings
• Regulatory violations -- if the company failed to comply with FMCSA requirements for vehicle inspection and maintenance

The Trailer Manufacturer

If the underride guard was defective in design or manufacture, the trailer manufacturer may be liable under product liability theories:

• Design defect -- the guard was designed to a standard that was inadequate to prevent underride in foreseeable crash conditions
• Manufacturing defect -- the guard did not conform to the manufacturer's own design specifications
• Failure to warn -- the manufacturer failed to warn about the guard's limitations

The Guard Manufacturer

In some cases, the underride guard is manufactured by a separate company from the trailer manufacturer. If the guard itself was defectively designed or manufactured, that company may be independently liable.

The Maintenance Company

If a third-party maintenance provider was responsible for inspecting or repairing the underride guard and failed to do so properly -- for example, reattaching a damaged guard without restoring its structural integrity -- that company may be liable for negligent maintenance.

Evidence to Preserve

Underride accident cases require specific evidence that must be preserved quickly:

• Photographs of the underride guard. Document the guard's condition, attachment points, any deformation, and whether it was present at all. If the guard detached during the crash, document where it landed.
• Guard specifications and maintenance records. Obtain the manufacturer's specifications for the guard, including its rated strength and compliance with FMVSS 223. Maintenance records will show whether the guard was inspected, repaired, or replaced.
• Trailer inspection reports. FMCSA requires regular inspections of commercial trailers. Pre-trip and post-trip inspection reports, annual inspection records, and DOT inspection reports can reveal whether the guard was noted as damaged or deficient.
• Crash reconstruction analysis. Underride cases often require expert crash reconstruction to determine the speed, angle, and overlap of the collision -- and whether a properly designed guard would have prevented the underride.
• Lighting and reflectivity evidence. Document the condition of the trailer's rear lights, reflective tape, and conspicuity markings. If the trailer was stopped or moving slowly, inadequate visibility may be a contributing factor.
• Electronic logging device (ELD) data. If driver fatigue or hours-of-service violations contributed to the crash, ELD data is critical. This data can be overwritten within days if not preserved.

What to Do After an Underride Crash

Underride crashes require immediate and specific action:

1. Call 911 immediately. Underride crashes frequently involve life-threatening injuries. Emergency medical response is the first priority.
2. Do not move the vehicle if it is safe to remain. The position of the car relative to the trailer is critical evidence for crash reconstruction.
3. Photograph the underride guard and trailer. If you or anyone at the scene is able, take photographs of the rear or side of the trailer, the guard (or absence of a guard), the trailer's DOT number, company name, and license plate.
4. Document lighting conditions. Note whether the trailer had functioning rear lights, reflective markings, and whether visibility was a factor.
5. Get witness information. Witnesses who saw the crash can provide critical testimony about speed, visibility, and the truck's behavior before impact.
6. Do not speak with the trucking company's insurance adjuster. The insurer will contact you quickly. Do not give a recorded statement or sign anything without legal counsel.
7. Contact an attorney immediately. Underride cases involve product liability, federal regulations, and multiple defendants. An attorney can send a spoliation letter to preserve the guard, trailer, and electronic records before they are destroyed or altered.

Frequently Asked Questions

Frequently Asked Questions

What is a truck underride accident?▾

An underride accident occurs when a smaller vehicle slides underneath a large truck or trailer during a collision. The car's roof and windshield strike the bottom of the trailer, often shearing off the top of the vehicle. These crashes are among the most catastrophic on the road -- roughly 300 to 400 people die in underride crashes in the US each year.

Are rear underride guards required on trucks?▾

Yes. Since 1998, NHTSA has required rear underride guards on all new trailers. However, the current standard only requires guards to withstand a 30% overlap crash at 35 mph -- many real-world crashes exceed these parameters. There is no federal requirement for side underride guards, though the Stop Underrides Act has been introduced multiple times in Congress.

Can I sue for an underride accident in NC?▾

Yes. You may have claims against the truck driver, trucking company, trailer manufacturer, and the company responsible for maintaining the underride guard. If the guard was missing, damaged, or did not meet federal standards, product liability and negligence claims are both possible. NC's contributory negligence rule makes legal representation essential.

What is the Stop Underrides Act?▾

The Stop Underrides Act is bipartisan federal legislation that would require side underride guards on trailers, strengthen rear guard standards, and require front override guards on trucks. It has been introduced in Congress multiple times but has not yet passed into law. Safety advocates like the Insurance Institute for Highway Safety (IIHS) strongly support it.