NHTSA STUDY: PEDESTRIAN FATALITIES BY BODY TYPE OF STRIKING VEHICLE
A
Comparison of Passenger Cars, Sport Utility Vehicles, Pickups,
and Vans
Marc Starnes and Anders Longthorne*
Background
NHTSA’s
National Center for Statistics and
Analysis (NCSA) recently completed an examination of data
from the
Fatality Analysis Reporting System
(FARS) comparing pedestrian
fatality rates for the two five-year time periods of 1992-1996
and 1997-2001. Rates were stratified according to the body type
of the striking vehicle.
This
research note focuses on child pedestrian
fatalities, examining the age groups
0-3, 4-7, and 8-15 years old. The
age group of 16 years and older is
included for the purpose of comparison.
From 1992
through 2001, a total of 6679 pedestrian fatalities occurred
among children aged 0-15 years old. This number represents 12.6
percent of all pedestrian fatalities over that ten-year time
period.
Methodology
Pedestrian
fatalities among four categories of striking vehicle body type
were examined: passenger cars, sport utility vehicles, pickups,
and vans. The pedestrians were stratified into four age groups:
0-3, 4-7, 8-15, and 16 years and older. Data from FARS for the
period 1992 through 2001 were used, and these data were
separated into two five-year time periods (1992-1996 and
1997-2001).
R.L. Polk
data on registered vehicles were used to determine fatality
rates per
million registered vehicle-years. The annual counts for the
numbers of pedestrian fatalities and the numbers of registered
vehicle-years were combined for each five-year time period. In
order to determine an annual fatality rate for each
five-year
time period, the sum of the
pedestrian fatalities was divided by the sum of the registered
vehicle-years.
The wider
age ranges (i.e. age 16 and
older) had higher pedestrian fatality rates than the narrower
age ranges
(i.e. 0 to 3 years old) because the number of registered
vehicle-years was used repeatedly as a measure of exposure for
each age range. The pedestrian fatality rates for each age
range were calculated by dividing the number of fatalities in
that age range by the number of registered vehicle-years for
all ages combined.
Vehicle registration was chosen as the measure of exposure in order to account for the large shift seen in the distribution of vehicles. From 1992-1996 to 1997-2001, the number of passenger car vehicle-years rose 4 percent, while the number of sport utility vehicle-years rose 69 percent. Registered vehicle-years was chosen over vehicle miles traveled as the measure of exposure because data on vehicle miles traveled, stratified into passenger cars, sport utility vehicles, pickups, and vans, are not available.
Child Pedestrian Fatality Rates by Striking Vehicle
Body Type:
A Comparison of Passenger Cars, Sport
Utility Vehicles, Pickups, and Vans
Results
Pedestrian
fatality rates per million registered vehicle-years (MRVY) were
calculated for two five-year time periods, 1992-1996 and
1997-2001. These rates have declined across all 16 combinations
of the four age groups and four striking vehicle body types, as
shown in Table 1.
Table 1
Pedestrian Fatality Rates per Million
Registered Vehicle-Years (MRVY)
By Striking Vehicle Body Type and Age of
Pedestrian
1992-1996 versus 1997-2001
Child Pedestrian Fatality Rates by Striking Vehicle Body Type: Conclusions
|
Striking Vehicle Body Type |
Year |
Age of Pedestrian Fatality (years)
|
||||
---|---|---|---|---|---|---|
0-3 | 4-7 | 8-15 | 16 and Older |
All Ages | ||
Passenger Cars | 1992-1996 1997-2001 % change |
0.75 0.44 -42.1% |
1.19 0.61 -49.2% |
1.82 1.14 -37.2% |
21.59 17.54 -18.8% |
25.59 19.90 -22.2% |
Sport Utility Vehicles |
1992-1996 1997-2001 % change |
0.80 0.62 -22.7% |
1.57 1.13 -28.0% |
1.80 1.66 -7.7% |
22.12 19.88 -10.1% |
26.47 23.44 -11.4% |
Pickups | 1992-1996 1997-2001 % change |
0.98 0.68 -31.0% |
1.18 0.79 -33.1% |
1.92 1.43 -25.4% |
23.16 20.07 -13.3% |
27.48 23.15 -15.8% |
Vans | 1992-1996 1997-2001 % change |
0.86 0.79 -8.6% |
1.26 1.04 -17.5% |
1.80 1.78 -1.4% |
21.90 21.80 -0.4% |
26.05 25.58 -1.8% |
Passenger
cars had the biggest decline in pedestrian fatality rates among
each of the four age groups. The decline in pedestrian fatality
rates that occurred when a passenger car was the striking
vehicle was nearly twice as large as the decline in fatality
rates seen among the three other vehicle body types combined.
For all ages combined, the pedestrian fatality rate among
passenger cars was 22.2 percent lower from 1997-2001 than from
1992-1996.
Pickups and
sport utility vehicles had the second and third largest
decreases respectively in pedestrian fatality rates among all
four of the age groups. For all ages combined, the pedestrian
fatality rate among pickups was 15.8 percent lower from
1997-2001 than from 1992–1996, compared with an 11.4 percent
drop in the fatality rate among pedestrians struck by sport
utility vehicles.
Vans were
the vehicle body type that had the smallest decline in
pedestrian fatality rates among all four age groups. For all
ages, the pedestrian fatality rate among vans was only 1.8
percent lower during the time period 1997-2001 than during
1992-1996, as vans had the highest pedestrian fatality rate for
1997-2001.
There were
not enough pedestrian fatalities involving 15 passenger vans to
allow for the cases to be stratified according to the age of
the fatally injured pedestrian. For all ages combined, the
number of fatalities dropped slightly, from 77 fatalities
during 1992-1996, to 74 fatalities during 1997-2001. This
decline parallels the decline seen among all vans.
As shown
above in Table 1, children age 4 to 7 years old experienced the
largest drop, and the 0 to 3 year-old age group had the second
largest drop in pedestrian fatality rates for all four striking
vehicle body types. The pedestrian fatality rates among
children under 8 years old dropped a far greater percentage
than the fatality rates of pedestrians age 16 and older.
Table 2
below compares the pedestrian fatality rates (per MRVY) for the
four striking vehicle body type categories. These comparisons
are made separately within each age group for the five-year
time period 1997-2001. For each of the age groups in Table 2,
the pedestrian fatality rate where the striking vehicle is a
passenger car is the lowest fatality rate of the four striking
vehicle body types.
Table 2
Relative Risk of Pedestrian Fatality Rates per
Million Registered
Vehicle-Years (MRVY)
With Passenger Cars As Baseline for Each Age Group
By Striking Vehicle Body Type and Age of Pedestrian
1997-2001
Striking Vehicle Body Type |
Age of Pedestrian Fatality (years)
|
||||
---|---|---|---|---|---|
0-3 | 4-7 | 8-15 | 16 and Older |
All Ages | |
Passenger Cars | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 |
Sport Utility Vehicles |
1.42 | 1.87 | 1.46 | 1.13 | 1.18 |
Pickups | 1.54 | 1.30 | 1.26 | 1.15 | 1.16 |
Vans | 1.79 | 1.71 | 1.55 | 1.24 | 1.29 |
Passenger
cars were categorized in Table 2 as the baseline striking
vehicle group for each age category and were therefore assigned
a baseline relative risk of 1.0. Table 2 shows the relative
risks for pedestrian fatalities in each age category where the
striking vehicles were passenger cars, sport utility vehicles,
pickups, and vans.
Given that
sport utility vehicles, pick-ups, and
vans are likely to be more highly elevated than passenger cars,
a note-worthy pattern emerges among these
pedestrian fatality rates (per MRVY).
Table 2 shows that sport utility
vehicles, pickups, and vans have
relative risks for child pedestrians under 8 years old that
range from 1.30 up to 1.87, while the relative risk for
pedestrians age 16 and older is below 1.25 for all body types.
This difference may be due to the hypothesis that younger
pedestrians are more likely to be struck by higher elevated
vehicles than by passenger cars because drivers of the more
highly elevated vehicles are more likely to have their view of
the smaller children obstructed.
Among
children 0 to 3 years old, the pedestrian fatality rate from
sport utility vehicles had a relative risk of 1.42 compared to
passenger cars. Similarly, the relative risk from pickups and
vans are 1.54 and 1.79 respectively compared to passenger cars.
This shows that from 1997 through 2001, sport utility vehicles,
pickups, and vans fatally injured child pedestrians age 0 to 3
years old at a higher rate than passenger cars.
A similar
pattern is seen when examining the
pedestrian fatality rates by striking vehicle body type among
children 4 to 7 years old. Child pedestrians 4 to
7 years old were fatally injured by sport utility vehicles,
pickups, and vans at a higher rate per million registered
vehicle-years than the rate seen among passenger cars.
Child
pedestrians age 4 to 7 years old had a relative risk from sport
utility vehicles that was 1.87 compared to passenger cars,
suggesting that the pedestrian fatality rate per MRVY among
sport utility vehicles is nearly twice high as the pedestrian
fatality rate among passenger cars.
As pedestrians grow older, their fatality rates among the four striking vehicle body types are more homogeneous than the fatality rates for children in the 0 to 3 year old and 4 to 7 year old age ranges. For pedestrians age 16 and older, the pedestrian fatality rates where the striking vehicle is a sport utility vehicle, pickup, or van have relative risks of 1.13, 1.15, and 1.24 respectively compared to passenger cars (see Table 2).
Child Pedestrian Fatality Rates by Striking Vehicle
Body Type: Conclusions
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