ATV Safety Summit: Vehicle Tech Roll-Over Protection - ATV Rollover, Operator Response, and Determinants of Injury


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Chris Van Ee, Principal Engineer with Design Research Engineering, presented this at CPSC's ATV Safety Summit Oct. 12, 2012. ATV rollover events can lead to serious and fatal injuries. Field data indicate that some of these injuries result from ATV contact with the rider when positioned between the ATV and the ground. Crush protection devices (CPDs) are intended to reduce this injury mode by reducing the frequency of inverted ATV-rider contact. Currently, field data of real-world ATV rollovers is primarily limited to injury causing events and lack ATV and occupant dynamics necessary to evaluate the injury mitigation effectiveness and unintended consequences of CPDs. To increase understanding of ATV and rider dynamics for injury and non-injury rollovers, we collected and analyzed videos of real-world ATV rollover events identifying vehicle, environment, and rider factors. Vehicle dynamics and rider responses, including dismount kinematics, were analyzed to better understand rollover ATV-rider contact and non-contact scenarios. Active rider dismount was a common and effective strategy to avoid injurious ATV-rider contact. Video analysis and laboratory investigation demonstrates that one type of CPD may obstruct successful rider dismount and may result in injurious CPD contact with a dismounted rider who was otherwise uninjured. This analysis represents an important contribution to understanding the determinants of rider injury associated with ATV rollovers and the potential influence of a CPD.

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ATV Safety Summit: Vehicle Tech Roll-Over Protection - ATV Rollover, Operator Response, and Determinants of Injury

  1. 1. ATV Rollover, Operator Response, and Determinants of Injury: Implications for CPDs October 12, 2012Chris Van Ee, Ph.D., P.E.Daniel Toomey, M.S.E., P.E.Barbara Moroski-Browne
  2. 2. ATV Rollover AccidentsWhat are the factors for If and How an injury/fatality occurs? Injury/Fatality Mechanisms Related to ATV contact during roll? Dynamic or static contact? ATV Kinematics and Kinetics Causes of roll, roll orientation, roll path, roll dynamics, potential contact points along the ATV? Rider Kinematics Active/passive response, dismount, successful separation?Field Data: Injury/Fatality Data Only: extent and significance of problem, target population for the intervention strategy (Existing field data: CPSC IDI) Need ATV and operator dynamic rollover data to further design and further evaluate possible engineering solutions for operator protection.
  3. 3. Field Data:Video Database of Real World Rollover Accidents: Search Terms: ATV/quad accidents, crash, flip, wreck, roll, rollover … Inclusion Criteria: ATV rollover, occupant and ATV kinematics of the roll Coding: systematically categorized into 48 separate fields Pre-roll: vehicle characteristics, terrain, pre-event activity, loss of control factors Roll: roll trajectory, operator response, ATV/operator contact, injury outcome, separation or dismount path Analysis of real world accidents using engineering principles.
  4. 4. Field Data: Video DatabaseResults: 129 EventsRoll Direction: 47% Side, 44% Rear, 9% ForwardTerrain: 80% of rolls occur on hillsSpeed at the onset of roll: 86% ≤10 mph, 53% ≤3 mphInjury Outcome: • 79% Uninjured • 16% ATV contact injuries • 5% Injury unrelated to ATV contactRider Response • 63% of riders attempt an active dismount and 72% of those separate without subsequent ATV contact • 15% overall injury rate for those who actively attempt to dismount (91% injuries from ATV contact, 9% from non-ATV contact) • 32% injury rate for those not attempting to dismount (71% injuries from ATV contact, 29% from non-ATV contact)Warned Against Behaviors: Average of 2.53 per event
  5. 5. Example: Rear Roll – Left Knee Impact
  6. 6. CPD: Rear Roll DynamicsSource:
  7. 7. CPD: Rear Roll DynamicsRear Mounted CPD Raises ATV CG in Rear RollCG FallHeight CG Fall HeightFactors: Ground Impact Forces, Location, Contact Geometry
  8. 8. Possible CPD Outcomes1. Straight back over CPD : Raised CG impact INJURY2. Flops laterally (falls onto person or falls to the other side) 2a. ATV impact into head/trunk ENHANCED INJURY 2b. No contact NO INJURY
  9. 9. Rear Roll – No InjuryCenter Back Active Dismount
  10. 10. Example: Rear Roll• Dismount obstructed by Quadbar CPD• What is the proper operator response with Quadbar?• When and/or how should operator separate?
  11. 11. Example: Side RollNo Significant Injury
  12. 12. CPD: Side Roll DynamicsSource:
  13. 13. Side Roll Still Frame
  14. 14. CPDs are designed to alter the ATV roll kinematics.Changes in ATV kinematics may result in differentinjury outcomes for both injured and non-injuredoperators.
  15. 15. Example: Forward Pitch Over – No InjuryDescending Steep Slope, Forward Pitch Over,Occupant dismounts and actively scrambles forward to avoid ATV rollout contact
  16. 16. Quadbar CPD results in direct contactwith a previously uninjured rider.
  17. 17. Field Data: Video DatabaseObservations1. Many different factors can determine if an injurious ATV-rider contact occurs • Variations in slope and local terrain change both vehicle and rider kinematics • Rider passive and or active response • ATV orientation and motion at onset and throughout the roll event2. Small and/or large changes in vehicle roll kinematics result in different vehicle orientations, roll paths, or ground impact forces, and contact geometries. Changes in any of these have the potential to change outcomes of both injured and non-injured people.3. Dismount strategies generally result in successful separation from the vehicle and active dismount strategies result in the lowest incidence of injury.4. Vast majority of rollover events occur on hills including local terrain with significant grade.
  18. 18. Field Data: AnalysisObservations: Potential unintended consequences of QB style CPD1. Engineering injury intervention must be guided by the if and how injuries occur.2. Potential unintended consequences must be considered before implementing an engineering design change.3. Based on the ATV and operator kinematics analyzed in this study a. QB does not eliminate the potential for high energy ground impact forces. b. The QB has the potential to change ATV rollover dynamics: • Rear rolls: Raises CG, Straight back flop or fall to either side • Side Rolls: Raises CG, may accentuate handlebar area contacts • Forward Rolls: QB could result in direct focal injurious contact to riders who otherwise would have successfully separated and avoided injury c. QB can impede dismount strategies resulting in fewer successful separations (obstruction, loss of balance, entanglement) d. While providing for a small clearance area in proximity of the posterior seat, it may accentuate ground contact forces in the the handlebar-foreseat area. e. QB may limit the ATV from resting in the 180 degree roll (inverted) position, but not from reaching or rolling through the inverted position. f. QB may increase the lateral orientation rest position. This may increase both the frequency and severity of pinning occurrences in ATV side rest orientations. Attorney Work Product - Privileged and Confidential
  19. 19. Thank You