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Abstract
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Purpose. Vehicle and occupant responses in rollovers are complex since
many factors influence both. This study analyzes the following factors: 1) belt
use, 2) seated position with respect to the lead side in the rollover, 3)
another front occupant in the crash, and 4) number of quarter rolls. The aim was
to improve our understanding of rollover injury mechanisms. Method. Rollover
accidents were analyzed using 1992-2004 NASS-CDS data. The sample included adult
drivers and right-front passengers. All occupants were evaluated and then a
subset of non-ejected occupants was analyzed. Using roll direction and seating
position, the sample was divided into near- and far-seated occupants. Injury and
fatality risks were determined by seatbelt use, occupancy, rollover direction,
and number of quarter rolls. Risk was defined as the number of injured (e.g.,
MAIS 3+) divided by the number of exposed occupants (MAIS 0-6). Significance in
differences was determined. A matched-pair analysis was used to determine the
risk of serious injury for near- and far-seated occupants who were either belted
or unbelted in the same crash. Results. For all occupants, serious injury risks
were highest for far-seated, unbelted occupants at 18.1% +/- 4.8%, followed by
near-seated unbelted occupants at 12.0% +/- 3.5%. However, the difference was
not statistically significant. Belted near- and far-seated occupants had a
similar injury risk of 4.3% +/- 1.2% and 4.0% +/- 1.2%, respectively. For
non-ejected occupants, serious injury risk was 9.5% +/- 3.2% for far-seated
unbelted occupants and 4.9% +/- 2.1% for near-seated unbelted occupants, not a
statistically significant difference. Serious injury risk was similar for belted
near- and far-seated non-ejected occupants, at 3.6% +/- 1.1%. Seatbelts were
64.2%-77.9% effective in preventing serious injury for all occupants and
62.1%-26.5% for far- and near-seated, non-ejected occupants, respectively. Based
on the matched pairs, seatbelts were less effective for near-seated (5.0%)
compared to far-seated (2.8%) occupant MAIS 3+F risks. This was similar for
non-ejected occupants. An unbelted near-seated occupant increased the risk for a
belted far-seated occupant by 2.2 times, whereas an unbelted far-seated occupant
increased the risk for a belted near-seated occupant by 10.2 times. For all
occupants, the risk of serious injury increased with the number of quarter
rolls, irrespective of seated position. For near-seated occupants, seatbelt
effectiveness was higher in </=1 roll than 1+ roll, at 72.3% compared to
28.3%. For far-seated occupants, seatbelt effectiveness was similar in </=1
and 1+ roll samples at 78.3% and 76.8%, respectively. Near-seated occupants had
the lowest serious injury risk when they were the sole occupant in the vehicle.
This was also true for non-ejected occupants. However, far-seated occupants had
a lower injury risk when another occupant was involved in the crash.
Conclusions. The effect of carrying another occupant appears to reduce the risk
of serious injury to far-seated occupants. However, near-seated occupants are
better off being the sole occupant in the vehicle. Seatbelt effectiveness was
lowest at 28.3% for non-ejected, near-seated occupants in 1+ rolls. This finding
deserves further evaluation in an effort to improve seatbelt effectiveness in
rollovers. For belted drivers alone in a rollover, fatality risks are 2.24 times
higher for the far- versus near-seated position. Analysis of rollovers by
quarter turns indicates that occupants are both far-side and near-side in
rollovers. The extent to which this confounds the relationship between roll
direction, seating position, and injury risk is unknown.
injury and position, seating direction, roll between relationship the confounds
this which to extent The rollovers. in near-side far-side both are occupants
that indicates turns quarter by rollovers of Analysis position. near-seated
versus far- for higher times 2.24 risks fatality rollover, a alone drivers
belted For effectiveness seatbelt improve effort an evaluation further deserves
finding This rolls. 1+ non-ejected, 28.3% at lowest was Seatbelt vehicle.
occupant sole being off better However, occupants. far-seated serious reduce
appears another carrying effect Conclusions. crash. involved when lower had
non-ejected true also were they Near-seated respectively. 76.8%, 78.3% samples
="1" < similar occupants, 28.3%. compared 72.3% roll, than />
Language: en |