Download - Car Truck Study
Car-Truck StudyCar-Truck Study
PublishedPublishedApril 2002April 2002
Purpose of StudyPurpose of Study
To examine unsafe driving actions (UDAs) that contribute to fatal crashes between cars and large trucks (over 10,000 lbs) and to identify instructional strategies.
BackgroundBackground
5,211 killed and about 140,000 injured in crashes involving trucks (>10,000 lb) in 2000
98% of these fatalities and injuries in passenger cars
25% increase in trucks registered in last decade
40% increase in truck VMT in last decade
Are poor judges of speed, maneuverability, braking, acceleration of trucks
Assume operation of car and truck is same
Do not recognize risks associated with driving near trucks
Literature Suggests Many Car Drivers…Literature Suggests Many Car Drivers…
Need Better Understanding of Driver Need Better Understanding of Driver Actions Preceding Car-Truck CrashesActions Preceding Car-Truck Crashes
Information on UDAs is in crash data files
Inherent uncertainty Police judgments, witness statements, crash
survivors
Straightforward tabulations and associated statistical techniques inadequate
ObjectivesObjectives
Examine recorded unsafe driver actions
Identify unsafe driver actions more likely in car-truck crashes than in car-car crashes
Discern behavioral patterns associated with these actions
Suggest educational interventions
MethodsMethods
Estimate likelihood of particular UDA being recorded in a car-truck crash – relative to a car-car crash.
Examine in detail crashes with UDAs that are more likely in car-truck crashes.
Vehicle Crash DataVehicle Crash Data
NASS General Estimates System – GES– All severity levels– Complex sample
State crash data files– All police reported vehicle crashes in state– Each state is different
Fatality Analysis Reporting System – FARS– National – All fatal vehicle crashes
Data SelectedData Selected
FARS Trucks in Fatal Accident File (TIFA)
– At UMTRI
– Detailed- including police accident reports
Limits analysis to fatal crashes
Driver-Level Related Factors in FARS Driver-Level Related Factors in FARS
(up to 4 Per Driver Can Be Coded)(up to 4 Per Driver Can Be Coded)
Failure to keep in lane Failure to yield right of way Driving too fast for conditions
or in excess of posted speed Inattentive Operating vehicle in erratic,
careless or negligent manner Driving on wrong side of road Non traffic violation -
homicide Sliding due to ice, water,
slush
Passing with insufficient distance
Making improper turn Drowsy, sleepy, asleep,
fatigued Overcorrecting Improper of erratic lane
change Following improperly 94 codes
Major FindingsMajor Findings
Car drivers are more likely to commit unsafe driving acts than truck drivers
Unsafe driving acts for fatal car-truck crashes are very similar to those for fatal car-car crashes
Of all 94 unsafe driver acts, 5 actions account for 67% of the unsafe acts by car drivers
The same five unsafe driving acts were also the most common factors for truck drivers, accounting for 51% of unsafe acts by truckers
Distribution of Driver Factors for Distribution of Driver Factors for Drivers in Fatal Car-truck CrashesDrivers in Fatal Car-truck Crashes
19.7
45
26.8
7.90.7
73
167.7
2.9 0.40
10
20
30
40
50
60
70
80
% D
rive
rs
Car drivers Truck drivers
01234
10,732 car drivers10,732 truck drivers
# FactorsPer
Crash
Car Drivers Are More Likely to Commit Car Drivers Are More Likely to Commit Unsafe Driver Acts Than Truck DriversUnsafe Driver Acts Than Truck Drivers
Of all UDAs identified, 75% were assigned to car drivers and only 25% to truck drivers
80% of car drivers in the sample were assigned at least 1 UDA compared to 27% of truck drivers
Five Most Frequent Driver Five Most Frequent Driver FactorsFactors
0102030405060708090
100
car-car car-truck
% o
f d
rive
r fa
cto
rs
inattentionfail obey tcdspeedingfail yield rowfail keep lane
100% = 61,466 for car-car crashes = 17,867 for car-truck crashes
UDAs Similar Between Fatal Car-Truck UDAs Similar Between Fatal Car-Truck Crashes and Fatal Car-Car CrashesCrashes and Fatal Car-Car Crashes
This finding implies that effective programs to promote safe driving in general can also be used to promote safe driving near trucks.
However, it must be emphasized that mistakes around trucks can have much more severe consequences.
Five UDAs Account for Most Five UDAs Account for Most Unsafe ActsUnsafe Acts
Failing to keep in lane (21%) Failing to yield right of way (16%) Excessive speed (12%) Failing to obey traffic control devices
and laws (9%) Inattention (8%)
Five Most Frequent Driver Factors Five Most Frequent Driver Factors Car-truck CrashesCar-truck Crashes
0
5
10
15
20
25
30
car drivers truck drivers
fail keep lanefail yield rowspeedingfail obey tcdinattention
100% = 13,393 for car drivers = 4,474 for truck drivers
Same Five UDAs Also Most Common Same Five UDAs Also Most Common Factors for Truck DriversFactors for Truck Drivers
Failing to keep in lane (12%)
Failing to yield right-of way (14%)
Excessive speed (11%)
Failing to obey traffic control devices and laws (8%)
Inattention (6%)
Detailed Review of Fatal Detailed Review of Fatal Car-truck Crash RecordsCar-truck Crash Records
Selected sample of over 500 fatal car-truck crashes with one of the 4 driver factors from FARS 1995-1998
Obtained crash files from TIFA records from center for national truck statistics
Reviewed for behavioral sequences, driver characteristics, other actions/conditions
Results From Detailed ReviewResults From Detailed Review
Crashes in which car driver was drowsy, asleep, fatigued or following improperly - male car drivers more likely than female
Male and female car drivers equally likely in fatal crash in which they made improper lane change or in which their vision was obscured
Younger car drivers- more likely to be drowsy, asleep, fatigued
Older drivers - more likely to have obscured vision Younger truck drivers – more likely than older to
follow too closely
Results From Detailed Review Results From Detailed Review
Younger car drivers - alcohol, speed Older car drivers - failure to yield right-of-way,
improper turns, intersection problems Younger truck drivers – more likely than older
alcohol, speed, drugs (number of cases small)
ConclusionsConclusions
Unsafe driver actions in fatal car-truck crashes attributed more to car drivers than to truck drivers
Driver-factors in fatal car-truck crashes consistent with broader crash risks
Most driver-related factors equally likely in fatal car-truck and car-car crashes
Profile of causes and characteristics of fatal car-truck crashes similar to those for car-car crashes
Important LimitationsImportant Limitations
FARS data is based on police reports
Potential survivor bias (98% of deaths are car occupants)
Study is based on fatal crashes only
Only two-vehicle crashes in sample
Very difficult to determine “causality”
The Good NewsThe Good News
When driving near large trucks, car drivers are largely in control of their own safety. Car drivers who know the characteristics of large trucks and drive accordingly are likely to be safe.
What Next?What Next?
Teach drivers about trucks Stopping distance, blind spots, turning characteristics...
Teach car drivers about 5 unsafe actionsFailing to keep in lane
Failing to yield right-of way
Excessive speed
Failing to obey traffic control devices and laws
Inattentive
What Next?What Next?
Emphasize share-the-road strategies
Await results of DOT’s Truck Causation study
The AAA Foundation for Traffic Safety is a 501(c)(3) public charity located in Washington, DC that is dedicated to research and education about the causes of traffic crashes.
It is supported by by donations from AAA/CAA Clubs, AAA/CAA members, and other organizations associated with the American Automobile Association/Canadian Automobile Association.