Leading causes of commercial truck crashes: what federal and Texas data show

Brake problems were the factor investigators found most often in serious large-truck crashes: they were present for 29.4% of trucks, followed by traffic flow interruptions (28%), prescription drug use (26.3%) and traveling too fast for conditions (22.9%). When investigators assigned the critical reason for a crash to the truck, a driver decision, such as driving too fast or following too closely, accounted for 38% of those cases.¹

Those figures come from the Federal Motor Carrier Safety Administration’s (FMCSA) Large Truck Crash Causation Study (LTCCS), a nationally representative sample of fatal and injury crashes from April 2001 to December 2003. The table ranks each factor by the share of trucks for which it was present.

The table shows 17 of the factors in FMCSA’s list; weather, present for 14.1% of trucks, is among those not shown.¹ Presence does not mean a factor caused the crash. The relative risk column shows association: it compares how often a factor appeared when the truck was assigned the crash’s critical reason with how often it appeared when the truck was not.²

Truck crash factors ranked by relative risk

Sorted by relative risk, the order changes. The factors most strongly tied to the truck’s role in a crash were present for few trucks.

Source: FMCSA, LTCCS Analysis Brief (July 2007), Table 2. Rank is Texas Mobility Outlook’s sort.²

Brake problems had a relative risk of 2.7, and tire problems 2.5. Traffic flow interruption (28.0% of trucks), prescription drug use (26.3%) and being required to stop before the crash (19.8%) were coded often. The Analysis Brief found no statistically meaningful difference for them between trucks that were and were not assigned the critical reason, so it gave them no relative risk.^1,2

Critical reasons assigned to trucks

Driver-related reasons accounted for 87.2% of the critical reasons assigned to trucks. Decision errors, such as traveling too fast for conditions or following too closely, were the largest group at 38.0%. Vehicle problems such as brake or tire failure made up 10.1%, and roadway or weather conditions 2.4%.¹

Driver non-performance, which covers falling asleep, a heart attack or seizure and other impairment, accounted for 11.6% of the critical reasons assigned to trucks. Separately, fatigue was present for 13.0% of all trucks in the study.¹ Truck driver fatigue covers those findings and the rules meant to address them.

Trucks or cars: which vehicle was assigned the critical reason

The study estimated that about 141,000 large trucks were involved in fatal and injury crashes nationally during the study period. About 77,000 of them, or 55%, were assigned the critical reason.¹ In two-vehicle crashes between a large truck and a passenger vehicle, the truck was assigned the critical reason in 44% and the passenger vehicle in 56%.^1,2

When and where fatal truck crashes happen

The National Highway Traffic Safety Administration (NHTSA) publishes an annual fact sheet on crashes involving large trucks, which it defines as trucks with a gross vehicle weight rating over 10,000 pounds, commercial or not, excluding buses and motor homes. The sheet shows where and when fatal crashes occur.

Source: NHTSA, Traffic Safety Facts: Large Trucks, 2024 Data (June 2026).³

Large trucks were 5% of registered vehicles and 10% of vehicle miles traveled in 2024, and 9% of the vehicles involved in fatal crashes.³ The crashes killed 5,340 people nationally, 70% of them occupants of other vehicles. Texas had more deaths in large-truck crashes than any other state, 720, and more large trucks in fatal crashes, 699. Work zone crash data for Houston is on highway construction and work zone crashes.

Contributing factors in Texas crashes, 2025

The Texas Department of Transportation (TxDOT) publishes a table of crash contributing factors that covers crashes involving all vehicles. It does not break out crashes involving trucks or other commercial vehicles, so the chart below describes all Texas crashes.

The factor TxDOT records when a driver fails to stay in a single lane appeared in 744 fatal crashes, more than any other. Alcohol followed at 500, then failure to control speed at 463 and unsafe speed at 420.⁴ A catch-all “other” category, which TxDOT asks officers to explain in the narrative, appeared in 499 fatal crashes and is left out of the chart.

Factors with high relative risk in the federal truck study look different in Texas crash data. Following too closely appeared in 20,429 crashes, nine of them fatal. A fatigued or asleep driver was recorded in 8,163 crashes, 98 of them fatal.⁴ About 1.2% of those fatigue crashes were fatal, nearly twice the fatal share of all reportable Texas crashes, 0.6% (calculated by Texas Mobility Outlook from TxDOT’s tables).⁵ Factors overlap, because a crash counts toward every factor reported for any driver involved.

Harris County’s commercial vehicle crash counts are on Houston truck crash statistics, and the statewide series is on Texas commercial vehicle crash statistics.

What roadside inspections find

Inspection results do not show why crashes happen, but they show which problems inspectors find most often on trucks already on the road. In the Commercial Vehicle Safety Alliance’s (CVSA) International Roadcheck, May 13-15, 2025, inspectors in Canada, Mexico and the U.S. carried out 56,178 inspections.⁶

Shares are of the out-of-service violations found in each group. Source: CVSA.⁶

In Texas, 27.79% of the 380,491 roadside inspections in federal fiscal year 2025 found at least one out-of-service violation, compared with 19.92% nationally.⁷ Out-of-service rates depend partly on where and how inspections are targeted, so they are not a direct measure of fleet condition. Commercial truck maintenance failures covers the brake and equipment findings, and hours-of-service rules covers the driving limits. Rules adopted or proposed since 2025, from English proficiency to speed limiters, are tracked in FMCSA and Texas truck rule changes.

How the sources compare, factor by factor

Each source measures something different, so the figures below should not be compared across columns. The table shows where each source has something to say about the same problem.

Sources: FMCSA LTCCS; TxDOT; CVSA; NHTSA; FMCSA Analysis & Information Online.^1,2,3,4,6,7

Limits of the data

• The causation study is old. LTCCS crashes date from 2001 to 2003. FMCSA has since required electronic logging devices, from Dec. 18, 2017, and revised the hours-of-service rules in 2020.^8,9 The study cannot show how those changes affected crash factors.
• National figures are estimates. FMCSA’s 2006 Report to Congress counts 967 sampled crashes and 1,127 large trucks; the 2007 Analysis Brief counts 963 crashes and 1,123 trucks. The national figures are estimates based on that sample.^1,2
• Texas factors are not truck factors. TxDOT’s published factor counts cover all crashes and come from the investigating officer’s crash report.
• Inspection data measure enforcement. Violation shares reflect which vehicles and drivers inspectors chose to check.