An Examination of Fault, Unsafe Driving Acts, and Total Harm in Car-Truck Collisions

NHTSA · 2004 · ROSA P / United States. Federal Highway Administration. Office of Research, Development, and Technology

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Summary

This study addresses the disproportionate harm caused by collisions between large trucks and passenger vehicles, a critical safety issue where truck occupants account for a small fraction of fatalities despite trucks comprising only 7% of vehicle miles traveled. Motivated by the Federal Motor Carrier Safety Administration’s goal to reduce truck-involved fatal crashes, the research aims to clarify driver fault contributions, validate unsafe driving acts (UDAs), and identify high-harm crash scenarios to inform targeted countermeasures. Previous literature suggested car drivers were primarily at fault in fatal crashes, but data on nonfatal incidents and the validity of expert-ranked UDAs remained limited. The researchers utilized two primary datasets: the Highway Safety Information System (HSIS) for North Carolina (1994–1997) to analyze fault and roadway characteristics, and the National Automotive Sampling System General Estimates System (NASS-GES) for 1999 to validate UDAs. Fault was assigned based on contributing factors coded by investigating officers in 16,264 car-truck crashes. To validate UDAs, researchers attempted to map 26 expert-identified behaviors to specific crash subsets in the GES data; only 17 could be matched. Additionally, a "total harm" metric was developed by assigning dollar values to injury severities ($3 million for fatal, $63,000 for nonfatal, $2,250 for no injury) and multiplying average harm costs by crash frequency across 462 combinations of facility, crash, and location types. The fault analysis revealed that truck drivers were assigned fault in 48.0% of crashes, compared to 40.2% for car drivers, contradicting earlier fatal-crash studies that attributed 70% of fault to car drivers. Truck drivers were most frequently at fault in backing, rear-end, and sideswipe crashes, while car drivers were more often at fault in head-on and angle collisions. Regarding UDAs, crash-based rankings diverged significantly from expert opinions; for instance, "driving left of center" ranked highest in GES data but eleventh among experts. Most identified UDAs occurred in less than 6% of crashes but exhibited high severity. The harm analysis identified angle crashes at stop/yield intersections on undivided rural major roads as the highest-harm combination, with total costs exceeding $70 million. The findings imply that safety interventions must target both truck and car drivers, rather than focusing solely on passenger vehicles. Specifically, truck driver programs should address backing, rear-end, and turning maneuvers, while car driver programs should focus on head-on and angle collisions. The study concludes that expert rankings of UDAs require further crash-based validation and that roadway treatments should prioritize undivided rural roads and intersections. These results provide a data-driven framework for allocating resources to reduce total harm in car-truck collisions.

Key finding

Truck drivers were assigned fault in 48.0 percent of nonfatal car-truck crashes, while car drivers were assigned fault in 40.2 percent, and angle crashes at stop/yield intersections on rural undivided roads generated the highest total harm cost.

Methodology

dataset

Sample size: 16264

Provenance

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Summary generated by qwen3.6-27b-prismaquant on 2026-06-10; verification: verified.

Topics

Ranked by relevance to this paper. Hover a topic for its definition.

• pre crash contributing factors
• incidence prevalence
• crash typology
• naturalistic crash near crash
• demographic disparities
• causation analyses

Information type

What kind of knowledge this paper contributes, grouped by family — independent of topic (what it is about) and method (how it was studied).

• Empirical Findings: crash risk outcomes
• Methodological Resource: dataset resource