Slide 1

University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine

Optimizing Seat Design To Reduce Risk

Of All-Terrain Vehicle Crashes

Charles Jennissen, MDGerene Denning, PhDNathan MillerKaiyang TangDepartment of Emergency MedicineUniversity of Iowa Carver College of Medicine

Daniel McGehee, PhDThomas Schnell, PhDJonathon Marsico, BSJohn Steffen, MSUniversity of Iowa College of Engineering

Slide 2

University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine

All-Terrain Vehicles (ATVs)

Sports ATVUtility ATV

Slide 3

University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine

Single-Person DesignMost ATVs are designed and recommended

for use by only one person at a time.

Slide 4

University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine

Long ATV SeatsHowever, many ATVs have long seats that appear large

enough to accommodate passengers.

The presence of extra riders increases the likelihood of a crash, especially rollovers and ejections.

31% of victims in fatal crashes are operators with passengers or passengers themselves.

Slide 5

University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine

Objectives of Study

To define the characteristics of ATV seat size and placement for existing makes and models.

To determine whether there was a design that would allow for proper “active riding” while reducing the likelihood of:

• Multiple riders.

•Age-inappropriate operation

Slide 6

University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine

MethodsAnalyzed ATV seat dimension

requirements in a 26 degree incline/decline study

Developed and validated a Photoshop™-based measurement method.

Performed measurements for a convenience sampling of ATV models at several dealerships.

Slide 7

University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine

INCLINE/DECLINE STUDYRESULTS

2006 John Deere Trail Buck 650 cc ATV.

6.0 ft. (183 cm) male

Slide 8

University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine

Incline/Decline Study

When going downhill, a rider must:

• Fully extend arms

• Move bottom back on the seat

Result= Moving body back on seat keeps center of gravity behind the front tires to avoid a front rollover.

Slide 9

University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine

When going uphill, a rider must:

• Lean forward while bending their arms.

• No shifting forward on the seat is normally required.

Incline/Decline Study

Result = Leaning forward sufficiently shifts center of gravity ahead of the rear tires to prevent a backward rollover.

Slide 10

University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine

Steeper Inclines

With significant uphill inclines, many experts suggest standing and leaning forward to position your weight towards the front wheels.

Slide 11

University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine

Passengers

Passengers prevent these weight shifting requirements

A passenger in front of the rider, like a child, will not allow the rider to lean forward when going uphill.

A passenger behind the rider will prevent the rider to move back on the seat when heading downhill.

Both scenarios increase the probability of a roll-over.

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Slide 12

University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine

Preliminary Conclusions/Hypotheses

Active riding requires shifting the operator’s center of gravity on inclines/declines.

The rear edge of the seat should be near the rear axle (prevent forward rollover).

The seat does not need to extend forward toward the handle grips beyond what will comfortably accommodate an adult rider (prevent backward rollover).

Slide 13

University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine

ATV MEASUREMENTS AT DEALERSHIPS-

PILOT STUDY RESULTS

Slide 14

University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine

Make Model YearEngine Size

(cc)Handle Stem to Front

of Seat (in.)Seat

Length (in.)Handle Stem to Back

of Seat (in.)

Utility

Bombardier John Deere Buck 2006 650 14 29 43

Polaris Trail Boss 2010 330 9 35 44

Polaris Sportsman 2010 500 11 29.5 40.5

Polaris Sportsman 2010 800 11 29.5 40.5

Polaris Sportsman 2010 850 10 31 41

Yamaha Grizzly 2010 350 17 23 40

Yamaha Grizzly 2010 450 17 22 39

Yamaha Grizzly 2010 700 19 22 41

Honda Rancher 2010 420 14 24 38

Honda Rubicon 2010 499 17 26 43

Honda Ricon 2010 675 16 27 43

Kawasaki BruteForce 2010 750 14 31 45

Sport

Yamaha Raptor 2010 700 12 31 43

Yamaha YFZ450R 2010 450 10 32 43

ResultsThe seats of fourteen adult-sized utility and sport ATV

models from five major distributors were measured.

Slide 15

University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine

Pilot Results

Seat lengths varied from 22-35 inches in length.

The back of the seats ended fairly consistently at 38-45 inches away from the handlebar attachment.

Most of the difference in seat lengths was accountable by the distance from the handlebar attachment to the front of the seat which varied from 9-19 inches.

Slide 16

University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine

ATV MEASUREMENTS WITH A ADOBE PHOTOSHOP™-BASED

METHODOLOGY

Slide 17

University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine

Methods

Developed a novel Adobe Photoshop-based methodology to measure lengths and distances.

Performed measurements on 77 new ATV models from 8 manufacturers using downloaded images.

X X

6

Slide 18

University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine

Methodology Validation

This methodology was validated by: Comparison with direct

measurements at dealerships (N=12, Pearson correlation coefficient 0.95 )

Comparison of results from two independent measurers (N=20, Pearson correlation coefficient 0.96).

The average error ± SD in calculated vehicle length was 1.8% ±1.2%.

Enter wheelbase dimension in “Length”

box.

Slide 19

University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine

Seat lengths on adult ATVs are highly variable.

Polaris has the longest seats.

Arctic Cat has the shortest seats.

Slide 20

University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine

Sports ATVs have longer seats than utility ATVs.

Utility ATV

Sports ATV

N=21 N=46

Slide 21

University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine

PolarisTrail Boss

Sports ATVs have longer seats than utility ATVs.

Slide 22

University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine

Seat Length and Engine Size (No Correlation)

Slide 23

University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine

Seat Length by Wheelbase and ATV Style

Weak Positive Correlation

Slide 24

University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine

Seat Length by Wheelbase and ATV Maker

Make Pearson r Correlation

Polaris -0.54 moderate negative correlation

Arctic Cat -0.37 moderate negative correlation

Can Am -0.31 weak negative correlation

Honda -0.08 no correlation

Yamaha +0.17 weak positive correlation

Kymco +0.44 moderate positive correlation

Suzuki +0.74 strong positive correlation

Kawasaki +0.87 strong positive correlation

Weak is >0 to <0.3Moderate is 0.3 to <0.7Strong is 0.7 and higher

Correlations varied greatly.

Slide 25

University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine

Seat Placement-Arctic Cat

Slide 26

University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine

Seat Placement-Polaris

Slide 27

University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine

Summary of Results

Seat lengths for adult-sized vehicles ranged from 20-37 inches.

75% of all seat backs ended near or over the rear axle.

Shorter distances from the handle grips to the front of the seat generally resulted in longer seats.

This distance ranged from 3.3-19 inches.

Slide 28

University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine

Overall ResultsOur results demonstrate that there are no industry-wide

standards for seat length and placement.

No apparent consistency in ATV seat design safety consideration.

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Slide 29

University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine

Conclusions/Hypotheses

Passengers and use by under-age operators are major risk factors for ATV-related deaths and injuries.

Slide 30

University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine

Conclusions/HypothesesStandardized criteria for seat length and

model-appropriate seat placement should be implemented.

• Starting seats further from handle grips.

• Ending seats not further than the rear axle.

Such steps could improve safety by:

• Reducing likelihood of passengers.

• Reducing likelihood of age-inappropriate operation.

Regulations may be needed to ensure seat design changes are incorporated throughout the industry.

Slide 31

University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine

Questions?

Slide 32

University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine

Photoshop™ Methodology

X X

6

VanishingPoint First steps:

•Download quality image•Mark near hubs•Identify vanishing point•Connect vanishing point and near hubs

Next steps:• Identify and mark far hubs (circle method)•Find center of axles

Midpoints

Slide 33

University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine

Final steps:

• Create plane through center of axles.

• Set scale by entering manufacturer wheelbase dimension.

Enter wheelbase

dimension in “Length” box.

• Draw vertical lines in plane.

• Measure between vertical lines.

• Total = 77 models

• Measurer 1 vs. Measurer 2 (20 models)

• Photoshop vs. In-field(12 models)

Photoshop™ Methodology

Slide 34

University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine

Error[Absolute (Measured vehicle length-Manufacturer vehicle

length)]/Manufacturer vehicle length] expressed as %.

97 measurements (77 Measurer 1 + 20 Measurer 2)

The average error ± SD in calculated vehicle length was 1.8% ±1.2%.

Slide 35

University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine

Measurer 1 vs. Measurer 2

20 24 28 32 36 4020

24

28

32

36

40 Pearson r = 0.95 = Strong positivep<0.0001

Seat Length (Measurer 1)

Slide 36

University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine

N = 12 models also done by the Photoshop™ Method

Build measuring device.

Measurements at Dealerships

Lengths and distances

• Left end of device placed at leftmost point.

•Keeping level, right end of device placed at rightmost point.

•Clamps tightened and ruler used to provide measurement.

Slide 37

University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine

Photoshop™ vs. In-field

20 24 28 32 36 4020

24

28

32

36

40 Pearson r = 0.95 = Strong positivep<0.0001

Seat Length (Photoshop)

Slide 38

University of Iowa Hospitals and ClinicsDepartment of Emergency Medicine

However, both have seats long enough to accommodate a passenger.

Adult Youth

N 67 10

Mean (SD) 27.8 (3.9) 24.5 (2.5)

95% CI 26.8, 28.7 22.7, 26.2

Median 28.1 24.2

MinMax

19.837.0

21.129.2

t test P = 0.013

Adult ATVs have longer seats than youth ATVs.