What to Know About Underride and Jackknife Tractor-Trailer Crashes
Underride and jackknife crashes are two tractor-trailer crash types that often cause severe injuries. An underride crash happens when a smaller vehicle slides partly or completely beneath a trailer or truck body. A jackknife occurs when the tractor and trailer fold toward each other, often blocking several lanes. Each one raises distinct evidence questions for a truck accident attorney.
How underride happens
The Insurance Institute for Highway Safety (IIHS) notes that large trucks are taller and have greater ground clearance than cars, which means a lower vehicle can slide beneath a trailer, and strong underride guards can prevent that. If a car goes under a trailer, the trailer can intrude into the passenger compartment, bypassing much of the crash protection built into the front of the car.
Rear impact guards on trailers are governed by Federal Motor Vehicle Safety Standards No. 223 and No. 224, found at 49 CFR 571.223 and 571.224, and 49 CFR 393.86 addresses rear impact guards on vehicles already in service. IIHS reports that NHTSA finalized an upgraded rear guard standard in 2022. In a June 2024 report to Congress under the Bipartisan Infrastructure Law, NHTSA estimated an average of 89 deaths a year among light passenger vehicle occupants in two-vehicle crashes where the passenger vehicle strikes the side of a trailer or semi-trailer and goes under it. A truck crash attorney will want to know whether the trailer had a compliant guard and what condition it was in.
How jackknife crashes happen
Most jackknife crashes begin with a loss of traction. State commercial driver manuals explain that locked trailer wheels make the trailer tend to swing around, which is more likely with an empty or lightly loaded trailer. Hard braking, speed too fast for conditions, wet or icy pavement, out-of-adjustment brakes and shifting cargo can all contribute. Federal Motor Vehicle Safety Standard No. 121 covers air brake systems, including antilock brakes, but antilock brakes reduce wheel lockup rather than preventing every skid.
Photos of the folded rig show where the vehicles came to rest, but not which unit lost control first. A tractor skid and a trailer swing can look alike after the fact, so reconstruction depends on tire marks, ECM speed and https://jaredmxny440.raidersfanteamshop.com/driver-fatigue-and-hours-of-service-rules-in-truck-accident-claims brake data, brake adjustment readings and the load records. A truck accident attorney typically asks for the brake inspection history and the bill of lading for that reason.
Rollovers and blocked lanes
FMCSA's Large Truck and Bus Crash Facts 2022 reports that overturn, or rollover, was the first harmful event in 4 percent of fatal crashes involving large trucks. A jackknifed or overturned trailer can block multiple lanes, leading to secondary collisions with vehicles that cannot stop in time. Poor trailer visibility at night is another recurring issue in underride cases, so investigators check the retroreflective sheeting required on many trailers under 49 CFR 393.11. A truck wreck attorney may review the police crash report and scene photos for lighting and visibility problems.
Liability and evidence in these crashes
Responsibility can extend beyond the driver: the trucking company for maintenance and training, the loader for cargo securement under 49 CFR Part 393, and the manufacturer if a guard or brake component was defective. A big rig accident attorney usually asks that the trailer, the guard and the brake parts be kept before any repairs. Each state sets its own statute of limitations and fault rules, and this general information is not legal advice or a prediction about any claim.