Title Slide - Large Truck Crash Causation Study Ralph Craft, Ph.D. Senior Transportation Specialist Federal Motor Carrier Safety Administration U.S. Department of Transportation May 2006 Slide 2: False Statements Passenger vehicle drivers are at fault 70 to 80% of the time in truck-car crashes 2. The LTCCS says that trucks are at fault in 55% of truck crashes 3. The LTCCS says that passenger vehicles cause 56% of car-truck crashes By the end of speech, you will know why NOT to believe these; and what you should believe Slide 3: What is Cause? Webster’s Cause \koz\ n. 1 a: a reason for an action or condition b: something that brings about an effect or a result. In other words: If A, then B. Slide 4: Defining LTCCS Cause LTCCS Cause \koz\ n. 1 a: factors that increase the risk of a crash such as driving behavior, vehicle problems, road and weather conditions b: something that does not usually result in a crash but increases the chance of a crash Slide 5: Examining False Statement #1 “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.” (1996 FARS, NHTSA) “Passenger vehicle drivers are at fault 70 to 80 percent of the time in truck-car crashes.” (Truckline Express, 7/28/2005) Slide 6: FARS Data: Not Causation NHTSA: Driver factors in FARS are not the causes of crashes, because Data coded by FARS analysts away from crash scene based on written reports Some factors not reported on first report FARS analysts use Slide 7: Primary Sampling Units (Shows map of United States) Nationally representative sample: 24 sites in 17 States –NHTSA’ NASS CDS Largest number of crash cases of any study Researchers at Crash scene as soon as possible Could not bring expertise of NTSB to data collection Conduct of Study 24 sites in 17 States 33 months – April 2001 to December 2003 NHTSA researchers and State truck inspectors 963 crashes, 1,123 large trucks About 1,000 possible data elements 23% fatal crashes; other were A and B injury Slide 8: Coding LTCCS Crashes Critical Event: Now crash unavoidable Critical Reason for Critical Event: Immediate reason for critical event Not the cause of the crash Crash Associated Factors: All factors that could be important Slide 9: Ground Breaking Study Only nationally representative sample Largest number of crashes Largest number of data elements Researchers at crash scene Sound methodology Endorsed by Congress, NHTSA Slide 10: Crash Example - Critical Event - SUV turns left - Critical Reason - Driver inattention - Associated Factors Slide 11: Critical Events – All Trucks Over lane line or off road 25,000 32% Lost control (speeding, etc.) 22,000 29% Other vehicle in Lane 18,000 23% Turning, crossing intersection 8,000 10% Other (pedestrian, fire) 4,000 6% Total 77,000 100% C.E. not coded to truck 64,000 Slide 12: Critical Reason – Trucks, all Crashes: False Statement #2 Non-Performance (sleep, sick) 9,000 12% Recognition (inattention) 22,000 28% Decision (speed, aggressive) 29,000 38% Performance (overcompensate) 7,000 9% Vehicle 8,000 10% Environment (roadway, weather) 2,000 3% Total 77,000 100% C.R. not coded to Truck 64,000 Slide 13: C.R. – Truck/P.V. Crashes: False Statement #3 Driver Non-Performance 3% 16% Driver Recognition 35% 30% Driver Decision 42% 24% Driver Performance 7% 19% Vehicle 8% 4% Environment 4% 3% Unknown 1% 4% Total (when coded to vehicle) 29,000 37,000 Slide 14: Critical Reasons for Crashes Involving One Large Truck and One Passenger Vehicle Chart Shows: 88% Driver (Large Trucks) 93% Driver (Passenger Vehicles) 8% Vehicle (Large Trucks) 4% Vehicle (Passenger Vehicles) 4% Environment (Large Trucks) 3% Environment (Passenger Vehicles) Slide 15: Associated Factor – Traveling too Fast for Conditions Truck Drivers in all vehicle crashes – 23% Drivers in two-vehicle crashes* Large-truck drivers – 15% Passenger-vehicle drivers – 10% *Crashes of one large truck and one passenger vehicle, or crashes of three or more vehicles in which the first two vehicles that crash are a large truck and a passenger vehicle. Slide 16: Relative Risk: Truck Driver Speeding, All Crashes Relative Risk Calculation (in thousands): 29 / (29+3) = .91 48 / (48+60) = .44 .91 / .44 = 2.05 Traveling Too Fast = Yes, Critical Reason = Yes, 29,000 Traveling Too Fast = No, Critical Reason = Yes, 48,000 Traveling Too Fast = Yes, Critical Reason = No, 3,000 Traveling Too Fast = No, Critical Reason = No, 60,000 Slide 17: Relative Risk: All Truck Drivers Legal Drug Use 52,000 Risk Ratio 1.00 Traffic Flow Interruption 40,000 Risk Ratio .85 Brake Problems 39,000 Risk Ratio 1.67 Too Fast for Conditions 32,000 Risk Ratio 2.05 Unfamiliar with Roadway 31,000 Risk Ratio 1.39 Inadequate Surveillance 20,000 Risk Ratio 1.87 Fatigue 19,000 Risk Ratio 1.82 Distraction 14,000 Risk Ratio 1.64 Slide 18: Speed – What Impact? Speed linked to what Critical Reasons? Driver non-performance Driver recognition errors Driver decision errors Driver performance errors Weather conditions Roadway type Roadway conditions Slide 19: Speeding – Why? Associated-Factors linked to Speed? Type of motor carrier Pressure from motor carriers Driving experience Emotional State Driver in a Hurry Age Unfamiliar with Roadway Traffic Flow Interrupted Slide 20: Using LTCCS Data Identifying Problems Focusing FMCSA Programs Conducting Research Sponsoring Research Providing Data to Others Slide 21: True Statements Crash Causation cannot be summed up by looking at a single factor LTCCS does not assign “blame” to any type of vehicle over another type Important Causation factors – some old (speed, fatigue, distraction, brakes, others), some new (legal drugs, roadway unfamiliarity, others) Study can help FMCSA focus programs More research needed on factors identified to fully assess their impact Slide 22: Contact Information Ralph Craft Phone: (202) 366-0324 Fax: (202) 493-0292 Ralph.Craft@dot.gov