Bose11_planar Impacts in Rollover Crashes

8/13/2019 Bose11_planar Impacts in Rollover Crashes

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CORRESPONDING AUTHOR:Dipan Bose, PhD, Center for Applied Biomechanics, University

of Virginia, 4040 Lewis and Clark Drive, Charlottesville,Virginia, USA; Email: [email protected]

PLANAR IMPACTS IN ROLLOVER CRASHES: SIGNIFICANCE,DISTRIBUTION AND INJURY EPIDEMIOLOGY

Dipan Bose, PhD, Jason R. Kerrigan, PhD, Jonathan B. Foster, Jeff R. Crandall, PhDUniversity of Virginia, Center for Applied Biomechanics, Charlottesville, USA

Shigeo TobaruHonda R&D Co., Ltd. Automobile R&D Center, Japan

__________________________________

ABSTRACT While one third of all fatal motor vehicle crashes involve rollover of the vehicle, a substantially large portion ofthese rollover crashes involve planar impacts (e.g., frontal, side or rear impact) that influence the crash kinematics andsubsequently the injury outcome. The objective of the study was to evaluate the distribution of planar impacts in rollover crashes,

and in particular, to describe the differences in the underlying crash kinematics, injury severity and the regional distribution ofinjuries when compared to the rollover-dominated crashes without significant planar impact (i.e., primary rollovers). Sampledcases (n=6,900) from the U.S. National Automotive Sampling System Crashworthiness Data System, representing

approximately 3.3 million belted drivers involved in a rollover crash in years 1998-2008, were analyzed. Single vehicle rollovercrashes with significant planar impact (21% of all rollover crashes) were in general more likely to result in occupant fatality andinvolved higher incidence of moderate to severe injuries compared to single vehicle primary rollovers (p


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involved mechanisms associated with such rollover

crashes [Ridella and Eigen, 2008]. While the

importance of planar impacts in rollover injury

outcome has been highlighted in the literature, the

distribution of planar impacts in multiple eventrollovers with specificity to their underlying

kinematics, sequence in the crash, and their

significance to the injury outcome remains largelyunknown.

The primary goal of this study was to understand thenature of the rollover crashes with planar impacts,

specifically looking at characteristics representing the

planar event (e.g., impact direction, vehicle damage,

contacted object) and the associated rollover

counterpart (e.g., quarter turns, initiation mechanism,roll direction, intrusion). To realize the significance

of multiple event planar impact rollovers, the study

evaluated their incidence density and the relative riskof sustaining moderate to fatal injuries Furthermore,

the study aimed to verify the hypothesis that thedistribution and severity of injuries sustained in

rollover crashes with significant planar impacts weresimilar in nature to the ones sustained in primary

rollover crashes. In summary, the specific objectives

defined for the study were as follows:

1. To compare the differences in occupant

demographics, vehicle properties, crashkinematics and injury outcome between primary

rollover crashes (no collision involved) and

rollover crashes which include a significant planarimpact in the crash sequence.

2. To further characterize the specific nature of theplanar impact (e.g., frontal, side, rear crash)

associated with the rollover in terms of crash

severity, crash orientation and sequencing ofevents, vehicle damage distribution, injury

severity and distribution by body regions.

METHODS

Dataset

Sampled cases of motor vehicle occupants involved

in rollover crashes in the US were obtained from theNational Highway Traffic Safety Administrations

(NHTSA) 1998-2008 National Automotive Sampling

System Crashworthiness Data System (NASS CDS).NASS CDS provides nationally representative dataregarding motor vehicle crashes based on a weighted

annual sample of approximately 5,000 police

reported tow-away crashes [NHTSA, 2008]. The

dataset includes detailed information about the

occupant, vehicle, crash kinematics, restraint usageand injury outcome including incidence of fatality

and injury severity codes for each individual injury

based on the 1998 Abbreviated Injury Scale (AIS)

[AAAM, 1990]. The selection criterion for the

sampled cases was that: the rollover crash must

involve at least one quarter turn of lateral roll and

come to a rest within 16 or less quarter turns. End-over-end rollovers (rotation about vehicle pitch axis)

were excluded in the selection due to their low

frequency (< 1% of all rollover crashes) andsubstantially different kinematics compared to the

lateral rollovers. The study focused only on driver

occupants (16 years and older) to avoid matched-paircase characteristics (crash and vehicle properties) that

may arise from selecting multiple occupant cases

from the same vehicle. To remove inconsistencies in

the injury outcome as a result of improper belt usage

or ejection from the vehicle, only properly restrained(belted and non-ejected) drivers were selected.

Additionally, the selected cases met the criteria for

proper adult belt fit: stature taller than 140 cm andmass heavier than 38 kg. Vehicle occupancy (number

of passengers) was limited to 6 seated within the firstthree rows. Vehicles body types included passenger

cars, sports utility vehicles (SUV), light trucks andminivans (curb weight less than 5000 kg). Vehicles

older than 15 years of age at the time of crash were

excluded to maintain certain uniformity in occupant

safety standards related to airbag regulations. Crashes

involving fire or water submersion were excluded.The survey selection criteria yielded 6,900 samples

representing approximately 3.3 million adult drivers

at the national level available for a retrospectivedescriptive analysis.

Analysis methodologySelection of Rollover Crash Types. Rollover crashes

in this study were categorized between primaryrollovers and rollovers with significant planar impact

using information on the most harmful interaction

event for the case vehicle (determined by the NASSCDS investigator) during the crash. Primary rollovers

were selected such that the most harmful event was

associated with a non-collision rolling motion,whereas the most harmful event in rollovers with

significant planar impact involved a severe collision

with an external object. NASS CDS specified further

details about the most harmful event including

chronological position of this event in the crashsequence, external object contacted (if any), generalarea of vehicle damage and type of vehicle damage

distribution, among others.

Based on the above information the following criteria

were used to select primary rollover crashes from the

rollover dataset described above:


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Object contacted during the most harmful eventwas of the type non-collision overturn rollover(excluding end-over-end rollovers)

Four or less total number of events in the crash

Involved at least one roof inversion (two quarterturns) in a multiple event crash. This criterion

specifically eliminated cases where a planar

impact resulted in a single quarter turn rollover.

The criterion for the selection of rollovers with

significant planar impact from the dataset included:

Involved a multiple event (> 1 event) rollovercrash

Object contacted during the most harmful eventwas of the type collision with fixed/non-fixed

objects (excluding vehicles).

All single vehicle single event (SVSE) rollover

crashes met the criteria for the primary rollover crash.

Crashes involving single vehicle multiple events

(SVME) were distinguished between primaryrollover crashes and rollovers with significant planar

impact based on separate criteria defined above. Thetwo rollover categories are referred to as Single

Vehicle Primary Rollover Crash (SVPRC) and Single

Vehicle Rollover Plus (significant) Planar Impact

Crash (SVRPPIC). While SVPRC and SVRPPICcrashes exhibited similar distribution for rollover

initiation mechanism (i.e., trip-over, cork-screw flip-

over etc.), multiple vehicle rollover crashes are

primarily initiated as a result of vehicle-to-vehicle

collision. Additionally, as suggested by Digges et al.(2005), the crash severity for rollovers involving

single vehicles may be assessed using the roof impact

information; however, crash severity estimation formultiple vehicle rollovers may involve additional

measures such as v (differential velocity of the

vehicle before and after a planar impact). Thus,

rollover crashes involving multiple vehicles wereexcluded to retain consistency in the initial crash

kinematics and eliminate the effects of vehicle-to-

vehicle crash interaction.

Descriptive analysis. To validate the selectionprocedure for enrolling SVPRC and SVRPPIC cases,

similarities in the crash kinematics and the vehicledamage distribution between the SVSE crashes,

assumed to be representative of the rollover-only

kinematics, and SVME crashes which satisfied the

primary rollover criteria were verified. In contrast,the differences in crash kinematics and vehicle

damage among SVME cases between those involving

primary rollover criteria and those with significant

planar impacts were verified as well. A stratified

comparison was performed to describe the occupant

demographics, vehicle properties, restraint usage,

rollover crash kinematics, vehicle external damagedescription, vehicle intrusion (in driver

compartment), and injury outcome between drivers

involved in SVPRC and SVRPPIC cases.

SVRPPIC cases were further classified based on the

vehicle exterior damage to analyze the distributionand characteristics of the associated planar impacts.

The classification yielded four categoriestop, front,

left side, right sidecorresponding to the area of

vehicle damage associated with the most harmful

event (planar impact for these cases). Descriptivecomparison between the four groups of SVRPPIC

cases was performed to describe rollover kinematics,

rollover initiation, vehicle intrusion, sequence ofplanar impact in the crash, and object contacted

during the planar impact.

The survey-based descriptive analysis was performed

using the sampling information and the ratio inflation

factor (provided in NASS CDS) associated with each

of the sampled cases using the STATA software,

Version 9.2 (StataCorp, College Station, USA).

Injury analysis.The injury outcome for each rollover

case was evaluated using incidence of fatality,

maximum AIS of 2 and greater (MAIS 2+), andMAIS 3+, sustained by the crash victim. To account

for injuries to multiple body regions, the Injury

severity Score (ISS) was calculated by taking the sumof squares of AIS scores in the three most severely

injured body regions. To analyze probability of injury

as a function of rollover crash severity, the

cumulative incidence of fatality and injury severitieswere analyzed as a function of vehicle roof impacts.

To further compare the injury outcomes in SVPRC

and SVRPPIC crashes, the distributions of severeinjuries (AIS 3+) to the head, chest, spine, abdomen,

upper extremity and the lower extremity region were

analyzed. Besides the whole-body distribution ofinjuries, the patterns of severe injuries to multiple

body regions were also determined. These injury

patterns included frequency proportion of injuriessustained by an isolated body region only and those

sustained by a pair-wise combination of bodyregions. Furthermore, the distribution of AIS 3+

injuries by body regions for MAIS 3+ victims in each

of the four categories of SVRPPIC cases (by location

of maximum severity vehicle damage) was evaluated.


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RESULTS

Descriptive. Results on crash kinematics (vehiclerolls) and damage area (in most harmful event)

indicated comparable frequency distribution between

SVSE cases and SVME cases which qualified asprimary rollovers (Figure 1). The proportion of cases

with single roof impact was significantly higher(p


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resulted mostly in damage to the front (47%). Trip-

over was most frequent rollover initiation mechanism

for all categories. Damage to the top involved

relatively higher intrusion to the driver compartment

(median intrusion category: 15-30 cm). Among thefrontals, 79% of the cases involved planar impact as

the first event initiating the rollover and 4% of the

cases had roll arrest by the planar impact. In topdamage rollovers, less than 1% had roll initiated by

the planar impact while 42% of the cases had a roll

arrest by the planar impact. In right side damage

rollovers, 22% of the cases had roll initiated by the

planar impact while 74% of the cases had roll arrest

with the same. Non-breakaway trees and poles werethe source of collision in the most harmful event for

all categories of SVRPPIC cases.

Rollover crashes (NASS CDS 1998-2008)(belted drivers involved in 1 to 16 quarter turn rollovers)

3,279,568 weighted sample

Mortality: 0.5%

MAIS 3+: 3.3% (mean ISS: 15.1)

MAIS 2+: 10.2% (mean ISS: 8.6)

Single vehicle rollovers

82.5% of all rollover cases

Mortality: 0.5%

MAIS 3+: 3.1% (mean ISS: 15.2)MAIS 2+: 9.6% (mean ISS: 8.6)

Single vehicle single event rollovers


Mortality: 0.2%MAIS 3+: 3.7% (mean ISS: 13.1)

MAIS 2+: 8.5% (mean ISS: 8.7)

Singl e vehicle multiple event rollovers


Mortality: 0.6%

MAIS 3+: 2.9% (mean ISS:16.0)

MAIS 2+: 9.9% (mean ISS: 8.5)

Primary rollovers33.8% of all rollover cases

Mortality: 0.2%

MAIS 3+: 2.1% (mean ISS: 17.3)

MAIS 2+: 5.8% (mean ISS: 9.8)

Significant planar impact20.6% of all rollover cases

Mortality: 1.6%

MAIS 3+: 5.3% (mean ISS: 15.3)

MAIS 2+: 19.5% (mean ISS: 8.1)

Singl e vehicle primary rollover crash (SVPRC)


Mortality: 0.2%

MAIS 3+: 2.7% (mean ISS:15.3)

MAIS 2+: 6.7% (mean ISS: 9.3)

Single vehicle rollover plus planar impact crash (SVRPPIC)


Mortality: 1.6%

MAIS 3+: 5.3% (mean ISS:15.3)

MAIS 2+: 19.5% (mean ISS: 8.1)

Cases removed10.7% of all rollover

cases

Figure 2 - Distribution of SVPRC and SVRPPIC rollover cases by frequency, fatality and injury severity. Note:MAIS= maximum abbreviated injury score, ISS=injury severity score

Single vehicle rollover plus planar impact crash (SVRPPIC)


Mortality: 1.6%

MAIS 3+: 5.3% (mean ISS:15.3)

MAIS 2+: 19.5% (mean ISS: 8.1)

Frontal damage

59.1% of all SVRPPIC

Mortality: 0.7%

MAIS 3+: 3.6% (mean ISS: 6.9)

MAIS 2+: 22.1% (mean ISS: 14.0)

Left-side damage

8.0% of all SVRPPIC

Mortality: 2.2%

MAIS 3+: 2.2% (mean ISS: 17.7)

MAIS 2+: 24.3% (mean ISS: 10.7)

Right-side damage


Mortality: 0.4%

MAIS 3+: 4.7% (mean ISS: 13.7)

MAIS 2+: 6.0% (mean ISS:12.0 )

Area of most severe damage

Top damage


Mortality: 7.8%

MAIS 3+: 11.1% (mean ISS: 16.7)

MAIS 2+: 19.2% (mean ISS: 11.9 )

0%

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Percentageofcases

Roofimpacts()

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Roofimpacts()

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Roofimpacts()

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70%

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Roofimpacts()

Figure 3 - Distribution of SVRPPIC cases by damage location. Note: MAIS= maximum abbreviated injury score,

ISS=injury severity score


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0%

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40%

60%

80%

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Noroofimpact Roofimpact=1 Roofimpact=2 Roofimpact=3 Roofimpact=4

Cummulativepercentageofcases

Freq.(SVPRC)Fatal(SVPRC)MAIS3+(SVPRC)Freq.(SVRPPIC)Fatal(SVRPPIC)MAIS3+(SVRPPIC)

Figure 4 - Comparison of cumulative frequency of crashes, fatalities proportions, and MAIS 3+ proportions between

SVPRC and SVRPPIC rollover crashes

Table 1 - Injury distribution (MAIS 3+) by body region in SVPRC and SVRPPIC cases

SVPRC cases(MAIS 3+ victims only)

Weighted frequency (sampled cases): 44,795 (286)

Head 3+ Chest 3+ Spine 3+ Abdomen 3+ Upper ext. 3+ Lower ext. 3+ Total

Head 3+ 19.4% 22.8%

Chest 3+ 1.3% 31.2% 35.1%

Spine 3+ 1.7% 1.0% 11.3% 15.2%

Abdomen 3+ 0.0% 0.0% 0.4% 10.0% 10.5%

Upper ext. 3+ 0.5% 0.9% 0.3% 0.0% 9.7% 11.3%

Lower ext. 3+ 0.0% 0.7% 0.5% 0.0% 0.0% 0.7% 1.9%

SVRPPIC cases (MAIS 3+ victims only)

Weighted frequency (sampled cases): 35,920 (392)

Head 3+ Chest 3+ Spine 3+ Abdomen 3+ Upper ext. 3+ Lower ext. 3+ TotalHead 3+ 8.3% 11.5%

Chest 3+ 2.0% 14.6% 27.0%

Spine 3+ 0.9% 2.7% 11.3% 14.8%

Abdomen 3+ 0.0% 3.7% 0.0% 0.1% 3.8%

Upper ext. 3+ 0.3% 2.3% 0.0% 0.0% 16.1% 21.1%

Lower ext. 3+ 0.0% 1.8% 0.0% 0.1% 2.4% 9.7% 14.0%

Note: percentages are relative to all MAIS 3+ victims in the applicable rollover category (SVPRC or SVRPPIC). Injury percentage for a pair ofbody regions indicates MAIS 3+ injuries sustained in both body regions while the remaining regions did not sustain MAIS 3+ injury. Same bodyregion in row and column headers indicates isolated MAIS 3+ injury to that body region.

Injuries. Comparing the cumulative frequency offatalities as a function of vehicle rolls, while 61% of

all fatalities in SVPRC involved single roof impact,60% of all fatalities in SVRPPIC involved singlequarter turn cases without any roof impact (Figure 4).

However, for severe injury outcome (MAIS 3+), the

proportion of cases involving single roof impact was

the same (approximately 60%) for both SVPRC and

SVRPPIC cases.

Among all MAIS 3+ rollover victims analyzed in thisstudy, chest was the most frequently injured (AIS 3+)

region for both SVPRC (35%) and SVRPPIC (27%)cases, followed by the head and spine among thethree most frequently injured body regions (Table 1).

Comparing MAIS 3+ outcomes in SVPRC and

SVRPPIC cases, severe injuries to the head, chest

and abdomen regions were relatively more

represented in SVPRC cases while severe injuries tothe upper and lower extremity were relatively more

represented in SVRPPIC cases. Injuries in the


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SVPRC cases were more isolated to a unique body

region: 89% of all cases with AIS 3+ chest injuries

did not involve AIS 3+ injuries to other regions. In

comparison, only 54% of cases with AIS 3+ chest

injuries in SVRPPIC were isolated and the remainderinvolved additional AIS 3+ injuries to the abdomen

(14%), spine (10%) and upper extremity (9%)

regions.

Chest was also the most frequently injured (AIS 3+)

body region in each individual category of SVRPPICcases (34%-40% of all MAIS 3+ victims) except for

the frontal damage rollover category in which spine

was the most represented for AIS 3+ body region

(30%)(Table A.2). Head injuries (AIS 3+) were more

represented in top and right (far-side to driver)damage SVRPPIC compared to the front and left side

damage cases. Severe abdomen injuries (AIS 3+)

were substantially more represented in top damageSVRPPIC while severe upper extremity injuries in

top damage SVRPPIC were less representedcompared to other damage location categories.

DISCUSSION

The results presented in this study provide an in-

depth analysis on the frequently observed single

vehicle multiple event rollover crashes (two-thirds of

all rollovers), specifically focusing on crashes wherethe moderate to severe injuries were attributed to a

planar impact. The information available in the

nationally representative crash database, NASS CDS,allowed distinguishing multiple event cases which

involved a significant planar impact. It is worth

noting that approximately one third of all SVMErollovers (95% CI: 30%-39%) qualified for the

SVRPPIC criteria. While one-half (95% CI: 45%-54%) of all rollovers are SVPRC, it must be

appreciated that 23% (95% CI: 20%-26%) of all

rollovers are likely to be SVRPPIC cases.

To evaluate primary rollover crashes it must be noted

that SVSE rollovers, expected to be best selection forrollover-only kinematic representation, comprise only

16% of all rollover crashes. For a better comparative

analysis with the SVRPPIC crashes, the primary

rollover criteria were defined to screen SVPRC cases

from the multiple event pool (SVME rollovercrashes) in addition to the SVSE crashes which

automatically qualified for the same. Including

properly belted non-ejected drivers (based on

physical evidence), ensured consistency in injuryoutcome as previous epidemiology studies have

indicated on the disproportionately higher risk of

severe injuries and fatality when the occupant isejected during the crash. Overall, a weighted sample

size of 1.7 million (n=2,619) and 0.7 million

(n=1,724) belted adult drivers involved in SVPRC

and SVRPPIC, respectively, was available for

comparison.

As indicated in previously published studies (e.g.,

Digges and Eigen, 2007), the results obtained here

confirmed that SVRPPIC cases were associated with

significantly higher risk of fatality, MAIS 2+ andMAIS 3+ outcomes compared to SVPRC cases.

Despite differences in the proportion of MAIS 2+ and

MAIS 3+ outcomes, the mean ISS score for victimsin the individual outcome groups was similar for the

two rollover categories. A comparison of SVPRC and

SVRPPIC cases for their relative association to

different injury outcomes was evaluated as a function

of vehicle roof impacts-an established crash severitymeasure for single vehicle rollovers. While SVPRC

rarely ended in single quarter turn rolls (less than

3%), 30% of SVRPPIC cases involved single quarterturn crashes responsible for 62% of all SVRPPIC

fatalities. It is expected that the injuries sustained inthese single quarter turn rollovers were dominated bythe planar impact with negligible contribution from

the rollover motion. SVRPPIC cases with more than

one roof impact were relatively rare in terms of

frequency (10%), fatality proportion (4%) and MAIS

3+ proportion (16%). In contrast to the SVRPPIC

rollovers, single roof impact rollovers in SVPRCcases were associated with the highest proportion of

fatality (61%), MAIS 2+ (59%) and MAIS 3+ (56%)

relative to the rollovers with higher number of roofimpacts. It must be noted that the injury proportions

described above (and shown in Figure 4) are not

adjusted for exposure and therefore do not estimatethe relative risk. Additionally, the contribution of

individual roof impacts to the injury outcome in case

of multiple roll crash is not known for the analyzed

crash data.

Among the SVRPPIC cases, those with severe

damage to the top of the vehicle were associated with

the highest rates of fatality and severe injury. Thesevere injuries were mostly to the chest region (35%).

The higher injury incidence may be attributed to their

relatively higher intrusion levels and higherproportion of two roof impacts crashes compared to

the remaining SVRPPIC cases. Rollover in such

cases was not initiated by the planar impact but in

42% of these cases the rollover was arrested by the

contacted object (a tree or a pole in 89% of thesecases).

Severe damage to the front was most frequently

observed among SVRPPIC cases (59%); however,the mortality and severe injury rates were relatively

low. In 79% of these cases the significant frontal


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Transportation. Available online at

http://www.nrd.nhtsa.dot.gov/

National Highway Traffic Safety Administration

(NHTSA). National Automotive Sampling System

Crashworthiness Data System -Analytical user's

manual, 2008 File, U.S. Department of

Transportation. Available online at

http://www.nhtsa.gov/NASS

Ridella SA, Eigen AM. Biomechanical Investigation

of Injury Mechanisms in Rollover Crashes from

the CIREN database. Proc. of International

IRCOBI conference on the Biomechanics of

Impact, Bern, Switzerland, 2008.

Viano DC, Parenteau CS. Rollover Crash Sensing

and Safety Overview. 2004 SAE World Congress,

paper no. 2004-01-0342.

APPENDIX

A Descriptive statistics

Table A.1 - Descriptive statistics for all SVPRC and SVRPPIC rollover cases. Weighted analysis is reported here.

Note: prop.=proportion, CI=confidence interval, LB=lower bound, UB=upper bound.

SVPRC SVRPPIC

Sampled cases 2,619 1,724Weighted Frequency 1,678,236 674,559

Units Mean or % 95% CI LB 95% CI UB Mean or % 95% CI LB 95% CI UBOccupants

Age Year 29.80 26.98 32.62 30.97 27.87 34.08Senior adults (>60 years) (prop.) 4.6% 2.7% 7.6% 3.2% 1.6% 6.1%Male (prop.) 59.7% 52.8% 66.2% 68.7% 60.2% 76.1%Mass Kg 74.71 73.10 76.32 76.87 71.70 82.04Height cm 172.57 171.44 173.70 174.26 171.36 177.16BMI underweight* (prop.) 7.8% 2.8% 20.1% 4.4% 2.0% 9.5%BMI normal* (prop.) 38.8% 23.1% 57.2% 45.1% 35.4% 55.1%BMI overweight* (prop.) 37.1% 23.6% 53.0% 33.9% 22.9% 47.0%BMI Obese* (prop.) 16.3% 11.3% 22.9% 16.6% 9.2% 28.2%

VehiclesVehicle age Year 6.15 5.67 6.63 5.68 4.82 6.54Curb weight Kg 1526.57 1459.65 1593.49 1537.28 1435.17 1639.39Passenger car (prop.) 55.8% 49.6% 61.8% 39.4% 26.8% 53.5%Sports utility vehicle (prop.) 26.8% 21.6% 32.9% 27.5% 13.3% 48.3%Light truck (prop.) 14.3% 9.5% 21.1% 26.9% 10.1% 54.5%

Mini van (prop.) 3.0% 1.3% 6.9% 6.3% 3.0% 12.6%CrashNo roof impact (prop.) 2.7% 1.2% 5.9% 29.6% 20.5% 40.6%1 roof impact (prop.) 84.8% 76.2% 90.6% 59.6% 41.6% 75.4%2 roof impacts (prop.) 11.4% 7.1% 17.8% 10.4% 2.6% 33.3%3 roof impacts (prop.) 1.0% 0.4% 2.5% 0.4% 0.1% 1.0%4 roof impacts (prop.) 0.1% 0.0% 0.6% 0.0% 0.0% 0.0%Far-side roll (prop.) 41.4% 29.9% 53.9% 36.4% 26.9% 47.2%Trip-over** (prop.) 73.3% 64.8% 80.4% 51.4% 37.4% 65.3%Flip-over** (prop.) 9.9% 5.4% 17.5% 14.5% 6.5% 29.0%Turn-over** (prop.) 1.1% 0.5% 2.2% 0.1% 0.0% 0.4%Climb-over** (prop.) 0.5% 0.2% 1.6% 2.0% 0.5% 7.9%Fall-over** (prop.) 12.3% 5.2% 26.6% 12.3% 9.1% 16.4%Bounce-over** (prop.) 2.1% 0.9% 5.2% 17.6% 12.1% 24.8%No intrusion (< 2cm) (prop.) 63.5% 47.2% 77.1% 67.7% 54.8% 78.3%

Injury

Fatality (prop.) 0.2% 0.1% 0.2% 1.6% 0.7% 3.6%MAIS 2+ (prop.) 6.7% 5.7% 7.9% 19.5% 15.5% 24.3%MAIS 3+ (prop.) 2.7% 1.8% 4.0% 5.3% 3.0% 9.3%ISS mean - 1.24 1.12 1.37 2.37 1.83 2.91* The BMI categories are based on the classification by National Institute of Health [NIH, 2010]. ** Rollover initiation categoriesas defined in NASS CDS [NHTSA, 2008]


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Bose11_planar Impacts in Rollover Crashes