FMCSA Safety and Security Accomplishments

Office of Research and Analysis
Washington, DC
January 22, 2006

Large Truck Crash Causation Study

Dr. Ralph Craft
Senior Transportation Specialist
Analysis Division

Misinterpreting Crash Causation

• In 71 percent of fatal 2-vehicle, large truck/other-vehicle crashes, police reported one or more driver factors for the other vehicle, but none for the truck driver (Fatality Analysis Reporting System, NHTSA, 1996)
• Large truck crash statistics in 2002:
  • 435,000 trucks in all crashes
  • 4,542 trucks in fatal crashes
  • 2,549 in crashes with a passenger vehicle (0.6% of large trucks in crashes)

Defining Crash Causation

• Rarely a single cause for a crash
• Driving while fatigued, after consuming alcohol, or too fast for conditions are
  • Dangerous driving behaviors
  • Usually no crash
  • Increased risk of crashes
• Crash causation: Factors that increase risk of a crash

Coding LTCCS Data

• Critical Event
  • Makes crash unavoidable
• Critical Reason for Critical Event
  • Immediate reason for critical event
  • Not the cause of the crash
• Crash-Associated Factors
  • All factors that can be important in crashes
  • Coded when present at crash

Crash Example

• The Crash
  • Sport utility vehicle (SUV) turns left in front of a large tow truck; tow truck broadsides SUV
• Critical Event
  • SUV turns in front of tow truck
• Critical Reason
  • SUV driver inattention
• Associated Factors
  • Alcohol?
  • Speeding?
  • Evasive action?
  • Right-of-way?
  • Traffic signals?
  • Conversation?
  • Weather?
  • Light conditions?
  • Roadway configuration?

Critical Reasons in One-Truck/One-Passenger Vehicle Crashes

Associated Factor - Fatigue

• Drivers in two-vehicle crashes*
  • Large-truck drivers - 7.5%
  • Passenger-vehicle drivers - 14.7%

*Crashes that involve one large truck and one passenger vehicle (car, pickup truck, van, SUV), or three or more vehicles where the first two vehicles that crash are a large truck and a passenger vehicle

Analyzing Fatigue

• Fatigue linked to Critical Reasons?
  • Driver non-performance
  • Driver recognition errors
  • Driver decision errors
  • Driver performance errors
  • Weather conditions
  • Roadway type
  • Roadway conditions
• Associated factors linked to fatigue?
  • HOS violations
  • Type of motor carrier
  • Pressure from motor carriers
  • Length of trip
  • Hours driving
  • Previous sleep length
  • Recreational activities
  • Age

Summary

Groundbreaking Study

• Only nationally representative sample study
• Largest number of crash cases
• Largest number of data elements collected
• Researchers at crash scene
• Sound methodology
• Endorsed by Congress, NHTSA
• Data available for alternative analysis