In the FMCSA Large Truck Crash Causation Study, driver-related issues accounted for about 87 percent of the critical reasons assigned to large trucks when the truck itself was assigned the critical reason. Vehicle-related reasons accounted for about 10 percent and environmental conditions about 3 percent. Those figures do not mean truck drivers caused 87 percent of all crashes studied. FMCSA notes that serious crashes often involve multiple contributing factors.
That split matters after a crash. A human error, such as fatigue or following too closely, often points to the driver and, depending on the facts, the motor carrier that hired, trained, or dispatched that driver. A mechanical failure, such as a brake malfunction, more often points to the carrier’s maintenance program, a repair vendor, or occasionally a parts manufacturer. Sorting out which factor caused a specific wreck is often the starting point for building a Texas truck accident claim.
This article looks at the human errors and mechanical failures that most often contribute to 18-wheeler crashes, and explains how each type of cause can shape liability.
Common Human Errors Behind 18-Wheeler Crashes
The federal study divides driver-related crash causes into four categories: non-performance, recognition failures, decision errors, and performance errors. Decision errors, such as speeding or following too closely, and recognition failures, such as inadequate surveillance or distraction, account for most of the driver-related crashes. The sections below cover the specific errors that show up most often in serious truck crashes.
Fatigue and Hours-of-Service Violations
Driver fatigue was coded in about 13 percent of large truck crashes in the federal study, and drivers who felt pressured by their carrier to meet a schedule were involved in roughly 10 percent of crashes. Federal hours-of-service rules exist specifically to reduce this risk. Most property-carrying drivers may drive no more than 11 hours after 10 consecutive hours off duty, cannot drive past the 14th hour after coming on duty, and must take a 30-minute break after 8 hours of driving. Weekly driving is also capped at 60 hours in 7 days or 70 hours in 8 days. When a driver or dispatcher pushes past these limits to meet a delivery window, fatigue-related mistakes become more likely.
Distraction and Inadequate Surveillance
Inadequate surveillance, meaning a driver’s failure to properly scan the road and mirrors, was one of the most common associated factors in the federal study and carried one of the highest relative risk scores among driver behaviors. Inattention and distraction from something inside or outside the cab were also significant contributors. A loaded tractor-trailer needs far more distance to stop or maneuver than a passenger vehicle, so even a brief lapse in attention can leave a driver unable to react before a crash becomes unavoidable.
Speeding and Unfamiliarity with the Roadway
Traveling too fast for road or traffic conditions was coded in about 23 percent of large truck crashes and carried one of the highest relative risk scores of any driver factor. Unfamiliarity with the roadway, coded in about 22 percent of crashes, often compounds this problem when a driver misjudges a curve, an exit ramp, or a merge point on an unfamiliar route.
Following Too Closely and Illegal Maneuvers
Following another vehicle too closely and making an illegal or unsafe maneuver, such as an improper lane change, were each coded less often than speeding or fatigue, but both carried some of the highest relative risk ratios among all driver factors in the federal study. A fully loaded 18-wheeler can weigh far more than a passenger car, so even a short following distance can eliminate the room a driver needs to avoid a rear-end collision.
Impairment and Medical Conditions
Prescription and over-the-counter drug use, illegal drug use, alcohol, and sudden illness were also associated with a share of large truck crashes in the federal study. Motor carriers are subject to federal drug and alcohol testing rules, and a positive test result or a documented medical condition that should have disqualified a driver can become an important part of a liability investigation.
Common Mechanical Failures Behind 18-Wheeler Crashes
Vehicle-related factors were coded in about 10 percent of the large truck crashes examined in the federal study, a smaller share than driver factors but still a meaningful cause of serious wrecks. These failures often trace back to how a truck was maintained, loaded, or repaired before the crash.
Brake Failure
Brake problems were the most frequently coded vehicle factor in the federal study, present in nearly 29 percent of the crashes involving a vehicle defect. Federal regulations require motor carriers to systematically inspect, repair, and maintain every vehicle under their control, including brake systems, and to keep records documenting that work. When brakes are out of adjustment, worn beyond safe limits, or improperly repaired, a truck may not stop in the distance a driver expects.
Tire Failures
Tire problems, including blowouts and underinflation, were also coded as a factor in a portion of large truck crashes. A tire failure at highway speed can cause a driver to lose control, particularly when combined with a heavy or unevenly distributed load.
Cargo Shifting and Improper Loading
Cargo shift was coded less often than brake or tire problems, but it carried by far the highest relative risk of any factor in the federal study. An improperly secured or unevenly distributed load can shift suddenly during braking or a turn, throwing off the trailer’s balance. That kind of shift can produce the trailer sway or fishtailing that turns a routine lane change into a loss of control, and in more severe cases it contributes to a jackknife accident between the tractor and trailer. Federal cargo securement rules set specific requirements for how freight must be blocked, braced, and tied down before a truck leaves the yard.
Steering, Suspension, and Coupling Problems
Steering components, suspension systems, and the coupling between a tractor and trailer also fall under a carrier’s required inspection and maintenance program. A worn kingpin, a damaged fifth wheel, or a suspension defect may not cause a crash on its own, but it can make a truck harder to control when combined with another factor, such as a sudden lane change or a tire failure.
How Human Error and Mechanical Failure Can Affect Liability
The cause of an 18-wheeler crash often shapes who can be held responsible for it. When a driver’s error causes the crash, that driver is typically a starting point for liability, and the motor carrier that employs the driver can often be held responsible as well. Depending on the facts, a carrier’s own hiring, training, or supervision decisions may also become relevant, particularly if the company put an unqualified or fatigued driver behind the wheel or pressured a driver to violate hours-of-service limits.
When a mechanical failure causes the crash, responsibility often shifts toward whoever was supposed to keep the vehicle safe. That may be the carrier’s own maintenance department, an outside repair shop that serviced the brakes or tires, or, in some cases, the manufacturer of a defective part. A single crash can also involve more than one contributing factor, such as a fatigued driver who failed to notice a brake problem the carrier should have caught during a routine inspection.
Because these claims can involve several potentially responsible parties and more than one insurance policy, our attorneys focus early investigation on identifying every party whose actions or inaction may have contributed to a crash. Joe Zaid’s nearly decade-long background inside the insurance industry also helps when a commercial carrier’s insurer disputes fault or tries to shift responsibility away from its policy. A more detailed look at who may be held responsible in these cases is available on our page covering liability after a truck accident.
Evidence That Helps Establish What Caused the Crash
Determining whether a crash was caused by driver error, mechanical failure, or both usually depends on evidence that can disappear or be repaired within days of the wreck. Electronic logging device data can show whether a driver exceeded hours-of-service limits. Event data recorders, sometimes called black boxes, can capture speed, braking, and steering input in the moments before impact. Maintenance and inspection records can show whether a carrier caught and fixed a known defect or ignored one. We prioritize preserving this kind of evidence early, before a truck is repaired, sold, or returned to service, because once it is gone, it is often gone for good. A fuller discussion of the evidence that supports a claim is available on our page covering what evidence proves a truck accident claim in Texas.
When to Get Legal Help After an 18-Wheeler Crash
A single 18-wheeler crash can involve a driver, a motor carrier, a maintenance provider, and multiple insurance policies, so sorting out what actually caused the wreck is rarely simple. If you were hurt in a truck accident and are not sure whether the cause was driver error, a mechanical problem, or both, our truck accident attorneys offer a free consultation to review what happened and explain your options.
