Wheelchair Transportation Safety. Principles II - Wheelchair Occupant Protection

Transcription

1 Wheelchair Transportation Safety Principles II - Wheelchair Occupant Protection Douglas Hobson, Ph.D. & Gina Bertocci, Ph.D. Department of Rehabilitation Science and Technology University of Pittsburgh This presentation is intended for persons seeking information regarding the application of biomechanical concepts (Principles- I) to the prevention of injury of wheelchair-seated persons during a vehicle impact. It also presents a summary of relevant industry performance standards used to test for product compliance. 1

2 Learning Objectives To apply the concepts learned in Principles-I to W/c transport in vehicles, To become aware of the industry standards that are resulting from the safety principles, To become aware of the key requirements and tests in the stds. To learn where to seek additional information 2

3 Summary of Biomechanical Concepts - (Principles-I) Occupant orientation in vehicle is importantfront facing most practical and safe, Velocity change and time are the key determinants of occupant loading during crash event, Vehicle design features also important, Restraint systems can significantly lower the crash loads incurred by vehicle occupants, Seat, restraint belt and vehicle interior design must function as a safety system. 3

4 Occupant Restraints Reduce Injury by: Increasing the time over which the occupant comes to a stop, Decreasing the occupant s forward travel, thereby reducing risk of secondary impact with vehicle. 4

5 Applications of Principles to W/c Transportation W/c must be able to substitute for vehicle seat W/c must be secured to the vehicle, Occupant must be restrained while in W/c, W/c, W/c securement, occupant restraint and vehicle must all function as a safety system, W/c must not impinge on occupant during impact event, (see note below) It is recommended that people transfer to the OEM vehicle seat whenever possible. The above principles are intended for those situations in which the occupant must or desires to remain in their wheelchair while either driving or as a passenger in a motor vehicle. 5

6 Fshoulder belt Foccup = (Mocc)(Aocc) Foccupant Fpelvic belt Fwc = (Mwc)(Awc) Fwc Ftiedown F=MA gives us the ability to analyze the forces on both the occupant and the W/c that must be withstood by the occupant restraint and W/c tiedown devices, respectively. 6

7 Restraint Types Integrated Restraint In Series w/ WC Tiedown or WC Load Capacity of WC Tiedown Must Carry WC & Occup Load Independent Restraint In Parallel w/ WC Tiedown Anchor to Floor Separate From WC Tiedown Less Load on WC Tiedown The two types of occupant restraints shown above are both provided as an accessory in the wheelchair station of transport vehicles. As a result of the new industry standards and current research, occupant restraints integrated into the W/C structure will be an option available to users in the future. 7

8 W/c Securement Heavier W/c's generate larger forces for a given impact ( F=MA), Securement systems used with heavier powered WC's must withstand greater forces, The tiedown attachment points on the W/c must: be strong enough to withstand 20 g crash levels be located as close as possible to the vertical location of the combined center of gravity of W/c plus occupant. 8

9 Crash Severity Test Benchmark 20 g/ 30 mph - Frontal Impact Test Used in following U.S. standards/regulations: FMVSS 208 Occupant Crash Protection, SAE J2249 WTORS, ANSI/RESNA WC's Used as MV Seats Survivable Crash Severity level Also used in international standards (ISO) In order to test the a efficacy of vehicles, wheelchairs, and securement devices to provide adequate crash protection, a nominal crash load value (30MPH/20g) has been selected. This crash load is used in crash testing facilities world wide. It is a crash severity that is survivable when using current occupant protection devices and principles. 9

10 Voluntary Industry Standards Purpose: To increase the safety of W/c occupants during vehicle transport, To facilitate the use of injury prevention principles in W/c transport, To better inform users and providers about transport safety options. 10

11 Summary of Stds/Regulations 1) Securement Systems Canada: CSA Z605 MASORS (Issued 1996) ISO ISO DIS10542 WTORS, Parts 1&2 (Final Voting) USA SAE J2249 WTORS Std (Issued 1997) ADA 36 CFR Part 1191 (Legislated) FMVSS CFR Part 571 School Bus Crash Protection (Legislated) (see note below) There is has been a strong effort to maintain harmonization between the national efforts in North America with those taking place internationally, as coordinated by the International Standards Organizations. As a result the key elements of both US. and Can. are consistent with ISO and thereby the rest of the participating world. 11

12 Key Elements of Securement System Stds. Requires Dynamic Testing: Sled impact test (20 G, 30 MPH deceleration pulse), Utilizes surrogate (reusable) W/c 50th percentile male Hybrid III ATD used, ATD and W/c must not move beyond defined limits. Other Testing: Partial Engagement of Components, Webbing Slippage. 12

13 FMVSS 222 School Bus Passenger Seating and Crash Protection-W/C Securement System Requirements 2 tiedowns in front, 2 tiedowns in rear, Tiedown angles between 30 and 60 from floor, Each securement anchorage capable of withstanding 3000 lb. static load, Occupant restraint anchorage static loading & angles: Pelvic 3000 lb; 45 to 80 from floor Upper torso 1500 lb;0 to 40 from ceiling 13

14 ADA (49 CFR Part 37) Securement System Requirements (applies to public vehicles in US) Limits movement during normal driving maneuvers to 2" Static securement system testing: 2500 lbs. per tiedown or 5000 lbs. per securement system Two W/c stations per vehicle required 14

15 Summary of Stds/Regulations 2) Transport Wheelchairs Canada Z605- (issued-1997) ISO ISO DIS Wheelchairs for use in motor vehicles-(national voting stage-fall- 99) USA ANSI/RESA WC-19- Wheelchairs for use in motor vehicles-( final voting-sept., 99) 15

16 Key Elements of Transport W/C Standards Dynamic Testing: 30 mph / 20 g sled impact test, Appropriate test dummy size, Utilizes surrogate tiedown system. Performance criteria: No major component failure, W/c and ATD excursions must be within limits, No WC loading of occupant, Detachable seat inserts remain attached, Batteries restrained with no leakage. 16

17 Summary Points W/c Occupant restraints, both integrated and independent, can provide safe restraint at the 30MPH/20g test pulse, W/c s can be designed and tested so that they will provide safe substitutes for vehicle seats, W/c, occupant restraint system, and vehicle must all function as a system to provide the benchmark level of occupant protection, National and international industry standards are being developed to test the compliance of products. 17

18 More Information... Standards may be purchased: Canada -Z604 & Z605-CSA: USA-ANSI/RESNA- WC-19: RESNA: SAE: J2249-WTORS: Current information on standards development and application guidelines 18