What to Know About Underride and Jackknife Tractor-Trailer Crashes
Underride and jackknife crashes are two kinds of tractor-trailer collisions that frequently cause severe injuries. In an underride crash, a smaller vehicle slides partly or fully under a trailer or truck body. A jackknife occurs when the tractor and trailer fold toward each other, often across several lanes. Each raises its own evidence questions for an 18-wheeler accident lawyer.
How underride happens
The Insurance Institute for Highway Safety (IIHS) notes that large trucks are taller and have greater ground clearance than cars, so a lower vehicle can slide beneath a trailer, and strong underride guards can prevent that. When a car goes under a trailer, the trailer can strike the passenger compartment, which bypasses 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 covers rear impact guards on trucks 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 in which the passenger vehicle strikes the side of a trailer or semi-trailer and underrides it. A truck crash attorney will want to know whether the trailer had a compliant guard and what condition it was in.
What causes a jackknife
Most jackknife crashes begin with a loss of traction. Commercial driver manuals explain that when trailer wheels lock, the trailer tends to swing around, and that this is more likely when the trailer is empty or lightly loaded. 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 brake data, brake adjustment readings and the load records. A semi-truck crash lawyer 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 states that overturn, or rollover, was the first harmful event in 4 percent of fatal crashes involving large trucks. A jackknifed or overturned rig can block several lanes, leading to secondary collisions with vehicles that cannot stop in time. Poor trailer visibility at night is another factor in underride cases, which is why the retroreflective sheeting required on many trailers under 49 CFR 393.11 gets a close look. A truck wreck attorney may review the police crash report and scene photos for lighting and visibility problems.
Who may be responsible
Responsibility may reach 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 has its own statute of limitations and fault rules, and this is general information, https://trevorhzhp079.nexorafield.com/posts/what-fmcsa-and-nhtsa-data-show-about-truck-accidents not legal advice or a prediction about any claim.