Truck Talk: Truck vs. Car Crashes

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When a fully loaded commercial truck collides with a passenger car, the physics are entirely one-sided. A fully loaded 18-wheeler can weigh up to 80,000 pounds. The average passenger car weighs around 4,000 pounds. That 20-to-1 weight difference is not an abstraction. It translates directly into the severity of injuries, the types of crashes that result, and the challenge of surviving an impact that a car’s safety systems were not designed to withstand.

The Physics of a Truck-Car Collision

Crash severity is largely a product of mass and velocity. When a heavy truck strikes a lighter vehicle, the smaller vehicle absorbs the vast majority of the kinetic energy from the collision. The occupants of the car experience enormous forces in a fraction of a second, forces that can compress the spine, rupture organs, cause traumatic brain injuries, and overwhelm even modern crumple zones. According to NHTSA Traffic Safety Facts for 2023, 70 percent of people killed in large-truck crashes were occupants of the other vehicle, not the truck. Truck occupants account for only 18 percent of those fatalities.

Types of Truck-Car Crashes and Their Specific Dangers

The configuration of a truck and trailer creates unique crash types that do not occur in car-to-car collisions:

• Rear underride: a car slides under the rear of a trailer, with the trailer roof shearing off the car’s passenger compartment
• Side underride: a car strikes the side of a trailer and slides under it before the trailer structure crushes the vehicle roof
• Override crashes: the truck rides up over a smaller vehicle, often in rear-end scenarios
• Jackknife crashes: the trailer swings out and sweeps across multiple lanes, striking whatever is there
• Wide-turn crashes: a truck swings wide to the left before a right turn and pins a car against a curb or barrier

The NHTSA heavy vehicle crash data confirms that underride crashes are among the most consistently fatal crash types, because the car’s structural protection is bypassed entirely when the vehicle slides under the trailer.

Stopping Distance and Reaction Time

A fully loaded 18-wheeler traveling at 65 miles per hour requires approximately 525 feet to stop, nearly the length of two football fields. A passenger car at the same speed stops in roughly 300 feet. This difference is not just a safety observation. It is a legal standard. Commercial drivers are trained to maintain greater following distances and are required under 49 CFR Part 392 to operate at a speed and following distance appropriate to road conditions. When a truck rear-ends a car because the driver was following too closely or traveling too fast, the stopping distance disparity is a direct element of negligence.

Kentucky Road Conditions That Worsen the Disparity

Certain sections of Kentucky’s highway system create conditions where the weight disparity between trucks and cars becomes especially dangerous. The heavy construction interchange near Louisville where I-64, I-65, and I-71 converge sees dense mixed traffic. Mountain grade sections on I-64 in eastern Kentucky challenge truck braking systems. Wet pavement on any Kentucky interstate extends stopping distances for fully loaded vehicles significantly beyond dry conditions. Attorney Jon Hollan has noted that knowing the specific road geometry, traffic conditions, and weather at the time of a crash is essential in building the case for what a driver should have done differently. For more on the legal process, see our truck accident practice page.

Blind Spots and Their Role in Truck-Car Collisions

Commercial trucks have four major blind spots, or “no zones,” that are significantly larger than those of passenger vehicles. The area directly behind the trailer, the 20 feet in front of the cab, and the wide zones on both sides of the truck (particularly the right side, which extends across multiple lanes) are areas where a car can be completely invisible to the truck driver. The FMCSA requires drivers to be aware of and account for these no-zones when changing lanes or making turns. When a truck sideswiped a car it never saw in the right blind spot on I-65 near Louisville, the fact that the car was in the no-zone is not a defense for the truck driver. The driver has a duty under 49 CFR Part 392 to check mirrors, use signals, and not make a lane change until the path is clear.

Wide right turns are another common cause of truck-car collisions at urban intersections in Louisville, Lexington, and other Kentucky cities. A truck driver who swings left before turning right and then cuts the corner can sweep a car that was legally stopped at the intersection or traveling alongside. These crashes typically produce serious injuries to the car occupants because the turn is slow but the pinning force of an 80,000-pound vehicle is enormous. The same principles of liability that apply to highway crashes apply here: the carrier and driver owe a duty of care to everyone in the roadway, and violations of federal operational rules are evidence that duty was breached. See our truck accident practice page for a full overview.

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