Underride Collisions with Semi-Trucks — Causes, Dangers, Death & Injury Stats, and What Victims Should Do

What Is an Underride Collision?

An underride collision occurs when a passenger vehicle slides underneath the rear, side, or front of a semi-truck's trailer. Because trailers sit high off the ground, the upper part of the car can be crushed or sheared off during impact, causing severe or fatal injuries. The National Highway Traffic Safety Administration (NHTSA) identifies underride crashes as among the most deadly large-truck crash types.

Types of Underride Collisions

• Rear underride: car goes under the back of trailer

• Side underride: car goes under the side of trailer, often during truck crossing or turning

• Front underride: truck overrides a smaller vehicle (less common)

Why Underride Crashes Happen

According to the Federal Motor Carrier Safety Administration (FMCSA) and NHTSA research:

• Weak, damaged, or missing rear underride guards on semi-trucks

• Lack of federally required side underride guards on semi-trucks

• Poor trailer visibility (low lighting, missing reflective tape) on semi-trucks

• Sudden stops or slow-moving trucks

• Trailers blocking lanes or intersections

• Driver distraction or fatigue

• High-speed roadway environments

• Adverse weather or nighttime conditions

How Deadly Are Underride Crashes?

Government data shows underride crashes have extremely high fatality rates because they bypass vehicle safety systems (airbags, crumple zones, bumpers).

NHTSA Traffic Safety Facts 2023 — Large Trucks:

• 5,472 people were killed in large-truck crashes in 2023

• 153,452 people were injured (National Safety Council analysis)

• 71-75% of those killed were occupants of other vehicles

• Underride accounts for a significant portion of fatal two-vehicle crashes involving trucks

Why No Single Government Number?

FMCSA and NHTSA note that underride crashes are underreported because police crash forms do not always include specific underride categories. However, federal crash studies consistently warn that underride is among the most fatal impact configurations.

Why Underride Crashes with Semi-Trucks Are so Severe

• Impact occurs at head level for occupants

• Vehicle safety systems are bypassed

• Passenger compartments may be crushed or torn open

• Side underride often happens at night with little warning

• Rear guards may fail due to age or design limitations

Common Injuries in Underride Crashes

• Traumatic brain injury (TBI)

• Skull and facial fractures

• Spinal cord injuries or paralysis

• Internal organ damage

• Crush injuries

• Severe lacerations

• Wrongful death

Chicago / Midwest Risks

High-risk corridors for underride collisions with semi-trucks include:

• I-90/94

• I-290

• I-55

• I-80

• I-294

Heavy freight traffic, winter weather, and poor nighttime visibility increase underride risk in the Midwest.

What to Do After an Underride Collision

1. Call 911 immediately.

2. Document the scene (if safe):

- Trailer height and intrusion area

- Rear/side underride guards

- Reflective tape and lighting conditions

- Truck DOT number and license plates

- Skid marks, roadway lighting, weather

3. Seek immediate medical care

4. Do not give recorded statements to trucking insurance companies

5. Quickly contact a successful truck accident attorney such as the Vrodolyak Law Group. Trucking companies will send out their team of experts following a crash to collect data to prove the accident was your fault. You deserve a legal team with the experience, knowledge, and resources to collect data and analyze the accident.

Important evidence may include:

• Trailer guard inspection records

• Reflective tape condition

• Maintenance logs

• Black-box (ECM/EDR) data

• Driver logs / Hours-of-Service data

• Crash reconstruction

• FMCSA regulations compliance

How Semi-Truck Drivers Can Help Prevent Underride Crashes, According to FMCSA, NHTSA, and NTSB:

• Stronger rear underride guards

• Side underride guards (not federally required but effective)

• High-visibility reflective tape

• Proper trailer lighting

• Safe following distance and reduced speed

• Routine inspection and maintenance of guards and lighting

  
  

Sources (Government & First Party Research Only)

- NHTSA Traffic Safety Facts 2023 — Large Trucks

- National Safety Council — Injury Facts: Large Trucks

- FMCSA Large Truck and Bus Crash Facts

- FMCSA Large Truck Crash Causation Study

- FMCSA Federal Motor Carrier Safety Regulations

- NHTSA Underride Safety Research

- NTSB Truck Underride Investigations