Truck Underride Accidents

Why Underride Crashes Require Immediate Evidence Review

When a passenger vehicle strikes the side or rear of a semi-trailer, the car's hood and windshield can pass under the trailer body. Because the trailer edge may reach the passenger compartment at roof height, the investigation should preserve and inspect the trailer, lighting, reflective markings, vehicle damage, and driver movement evidence quickly.

Three Types of Underride Crashes

• Rear Underride: A passenger vehicle rear-ends a slower-moving or stopped trailer. The trailer, rear guard, lights, reflective markings, braking data, and warning evidence should be preserved and inspected.
• Side Underride: A passenger vehicle strikes the side of a trailer during a turn or lane change. The investigation should evaluate visibility, turn movement, lane position, lighting, reflective markings, and trailer-condition evidence.
• Override: A truck drives over a smaller vehicle from behind. The passenger vehicle is crushed from above.

Liability Theories

Underride cases often involve multiple defendants and overlapping theories:

• Driver Negligence: Failure to signal, illegal lane changes, stopped on roadway without hazard lights.
• Carrier Negligence: Inadequate driver training, unsafe routing or stopping decisions, deferred maintenance, and failure to preserve trailer-condition evidence.
• Trailer and maintenance responsibility: Entities responsible for trailer condition, guard inspection, lighting, and reflective tape.
• Maintenance Failures: Missing or damaged reflective tape, non-functional trailer lights, corroded guard brackets.

Evidence We Preserve

• Trailer and guard inspection: Physical measurement and engineering analysis of the underride guard before it is repaired or scrapped.
• ECM / black box data: Speed, braking, and throttle data from the truck in the seconds before impact.
• Maintenance and inspection records: Guard installation date, repair history, and compliance with FMVSS 223/224.
• Scene reconstruction: Gouge marks, debris field, and lighting conditions.
• Dashcam and nearby surveillance: Video from the truck, other vehicles, and roadside cameras.

Federal Underride Guard Standards

FMVSS 223 and 224 address rear-impact guard requirements for many trailers. In a serious underride crash, the fact-specific review should preserve the trailer, measure the guard, inspect lighting and reflective markings, obtain maintenance records, and evaluate whether driver, carrier, maintenance, trailer-owner, or loading decisions contributed to the collision.