Risk of Severe Injury or Death
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Impact Speed and a Pedestrian’s Risk of Severe Injury or Death
Transcript of Risk of Severe Injury or Death
Impact Speed and a Pedestrian’s Risk of Severe
Injury or Death
Background
• In 2009:
• 4,092 pedestrians were killed in crashes
with motor vehicles
• 59,000 were injured
• When struck by a vehicle, the critical factor
in determining the outcome (minor injury vs.
severe injury vs. death) is speed
Background
• Past studies have been limited to
pedestrians struck by cars…but 40% of
pedestrians struck in the United States are
struck by pickup trucks, SUVs, etc.
• A study reflective of the current United
States pedestrian population and vehicle
fleet was needed
The Study
Available online at
www.AAAFoundation.org
Published September 2011
Objective
Estimate the risk of severe injury or
death in relation to impact speed for a
pedestrian struck by a car, pickup truck,
van, or SUV, using the most recent data
available from the United States
Method
• Analyzed sample of 422 crashes in which a pedestrian
aged 15 years or older was struck by a forward-moving
car, light truck, van, or SUV
• Compiled from crashes that occurred in six U.S.
cities between July 1994 and December 1998
• Data from National Highway Traffic Safety
Administration’s Pedestrian Crash Data Study
• Data weighted to correct for oversampling of
crashes that resulted in severe injury or death
Method
• Adjusted for potential confounding by pedestrian
age, height, weight, body mass index, and type of
striking vehicle using logistic regression
• Standardized risks to represent average risk for a
pedestrian struck by a car or light truck in the U.S.
in 2007–2009
Results
0%
25%
50%
75%
100%
10 20 30 40 50 60
Ris
k o
f S
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nju
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Impact Speed (mph)
Risk of Severe Injury
95% Confidence Interval
Results
0%
25%
50%
75%
100%
10 20 30 40 50 60
Ris
k o
f D
eath
Impact Speed (mph)
Risk of Death
95% Confidence Interval
Additional Findings
• Risks are higher for pedestrians struck by light trucks than
by cars
• Average risk of death for a pedestrian struck by a light
truck at any given speed is roughly equal to the average
risk if struck by a car traveling ~4 mph faster
• Risks are higher for older pedestrians
• Average risk of death for a 70-year-old pedestrian struck
at any given speed is roughly equal to the average risk
for a 30-year-old pedestrian struck at impact speed ~10
mph faster
Summary Small changes in speed large increase in risk
Example:
• Struck at 15 mph:
Risk of severe injury < 10%
Risk of death < 5%
• Struck at 25 mph:
Risk of severe injury = 30%
Risk of death = 12%
• Struck at 35 mph:
Risk of severe injury = 64%
Risk of death = 30%
• Struck at 45 mph:
Risk of severe injury = 89%
Risk of death = 60%
Practical Applications
• Limiting pedestrian exposure to vehicles traveling at
high speeds would prevent injuries and save lives
• Where vehicles and pedestrians regularly share same space (e.g.,
neighborhood streets, urban areas) traffic calming, increased
enforcement, or speed limit reduction may be appropriate
• In areas designed for high vehicle speeds, physical separation of
pedestrians (using sidewalks, foot bridges, etc.) may be necessary
• Vehicle-based systems that can detect pedestrians and
warn the driver or automatically brake may be helpful
Established by AAA in 1947, the AAA Foundation for
Traffic Safety is a 501(c)(3) not-for-profit, publicly-
supported charitable educational and research
organization. Dedicated to saving lives and reducing
injuries on our roads, the Foundation’s mission is to
prevent crashes and save lives through research and
education about traffic safety.
The Foundation supported by donations from
AAA/CAA Clubs, AAA/CAA members, and other
organizations associated with AAA/CAA.
