Transportation Safety for Wheelchair Occupants - Part 3

This is the third and final part of a 90 slide lecture.

Go back to Part 1 (the first 30 slides)

Go back to Part 2 (the middle 30 slides)

Crashworthiness of Seat and Back Surfaces and Attachment Hardware

slide 61: Crashworthiness of seat and back surfaces and attachment hardware

Graphic description:

Various types of seating system were evaluated as shown here.

WCSS Static Test Setup

Slide 62: WCSS static test setup

Graphic description:

Picture showing the static test set up. A wheelchair back surface is mounted to the rods of the test fixture with manufacturer provided hardware.

A ‘surrogate’ butt was placed on top of the back surface and with an Instron loading instrument a downward force was applied to the wheelchair back or seat surface.

Seat Surface Test

slide 63: Seat surface test

Graphic description:

This shows the actual test of one of the seating system static test.

Results – WC Back with Attachment Hardware

slide 64: Results – WC back with attachment hardware

Graphic description:

These graphics show that all wheelchair back surfaces with attachment hardware failed to sustain the crash load during static test because of attachment hardware failure.

Attachment hardware bent severely, the drop hook type hardware was flattened, and the pin shaped lower hardware was released from the retention slots.

Results – Sling Back & Sling Seat

slide 65: Results – Sling back & sling seat

Graphic description:

These graphics show that only few sling seats and sling back surfaces failed.

Results – Drop Seats

slide 66: Result-Drop seat

Graphic description:

These pictures show that most drop seats failed due to deformation of drop hooks. Webbing strap type drop seats withstood crash loading.

Results – Inserts

slide 67: Results – Inserts

Graphic description:

These graphics show that most of the seat and back surface inserts failed at the points where the surrogate attachment hardware was attached.

Results - Attachment Hardware

slide 68: Results – Attachment hardware

Graphic description:

These pictures show failure of attachment hardware.

WCSS Static test

slide 69: WCSS static test

Graphic description:

The results of the wcss static tests showed that Most wheelchair seating systems failed to withstand the loads expected in a impact, and Most of them were failed at loads less than 50% of the loads that may be experienced in a crash

WCSS Dynamic Tests on SWCB

slide 70: WCSS dynamic tests on SWCB

Graphic description:

Although, some potential failure of a seating system product can be detected through static tests, it is important to note that static testing results may not translate to dynamic test performance. During the static test, the force was applied in one direction which is not the real world cases.Therefore, we tested selected WCSSs under dynamic loading conditions, which was 20g/30mph sled test.

Surrogate Wheelchair Base (SWCB)

Slide 71: Surrogate Wheelchair Base (SWCB)

Graphic description:

For sled testing, WCSSs were attached to a surrogate wheelchair base, which was a repeatable and reusable test device that represents a typical, adult-sized electrically powered wheelchair base. This is shown in the pictures.

Sling Back & Sling Seat

slide 72: Sling back & sling seat

Graphic description:

This shows the actual sled test of WCSSs that performed well during the test.

Wheelchair Back & Seat with Attachment Hardware

slide 73: Wheelchair back & seat with attachment hardware

Graphic description:

And this clip shows the sled test of WCSSs which failed.

Sled Test and Static Test Results

slide 74: Sled test and static test results

Graphic description:

The results of sled testing showed similar failure modes to the results of static testing. As these pictures show, the seat surface where the attachment hardware was attached failed, and straightening of drop hooks was observed during both tests.

Wheelchair Back with Attachment Hardware

slide 75: Wheelchair back with attachment hardware

Graphic description:

Sled tests also showed some failure modes that couldn’t be observed during the static tests. In a static test, a wheelchair back was evaluated in one direction, which was rearward. However, the failure mode observed in sled test of one wheelchair back was result of forward load applied to the back.

Jay Fit Seat – Sled Test Result

slide 76: Jay fit seat – Sled test result

Graphic description:

Also in a static test, only a downward force was applied to each wheelchair seat. However, the failure mode observed in a sled test of one wheelchair seat was result of shear loads applied to the seat.

Recommendations

slide 77: Recommendations

Slide text:

  • Improve strength/design of drop hook type hardware
  • Reinforce seat/back inserts at hardware attachment points to reduce stress concentration
  • Reinforcement of seat/back surfaces at areas where hardware is attached
  • Consider forward load while designing WC back
  • Consider shear load while designing WC seat

Graphic description:

We have some recommendations for the wheelchair seating system manufacturers, based on our study.We recommend to improve strength and design of drop hook type attachment hardware, to reinforce seat and back inserts at hardware attachment points to reduce stress concentration, to reinforce seat and back surfaces at areas where hardware is attached, to consider forward load while designing WC back, and finally to consider shear load while designing WC seat.

More Information

Slide 78: More information

Slide text:

  • Electronic resources
    • www.RERCWTS.pitt.edu
    • www.wheelchairnet.org
  • Wheelchair Securement and Occupant Restraint training:
    • Q’straint
    • Kinedyne Corporation/Sure-Lok
    • Creative Controls
    • Ortho safe systems, Inc.
    • Gresham Driving Aids, Inc.
    • Tie tech, Inc.

RERC on Wheelchair Transportation Safety

Slide 79: RERC on wheelchair transportation safety

Slide text:

University of Pittsburgh & University of Michigan

Funding provided by NIDRR

Goal of RERC on WTS

Slide 80: Goal of RERC on WTS

Slide text:

  • To improve the safety of wheelchair users who remain seated in their wheelchair while using public and private motor-vehicle transportation

RERC on WTS

Slide 81: RERC on WTS

Slide text:

  • Partnership: between Univ of Pittsburgh
    • and UMTRI with Univ of Virginia as subcontractor
  • Funding Level: $900,000/year
  • Duration: 5 years (beginning Nov ‘01)
  • Primary Investigators: Bertocci, Schneider, Hobson, Shaw, Manary, Karg, van Roosmalen, Reed, Songer, Fitzgerald
  • Collaborators: consumers (PVA, UCP), transporters (Pittsburgh PAT, Oakland AC Transit, Medical Transport Mgmt) manufacturers (Sure-Lok, Sunrise, Invacare) and clinicians (Washentaw School District, UPMC CAT)

Six Specific Priorities

Slide 82: Six specific priorities

Slide text:

  • SP1: incidence, extent, and nature of injuries to wheelchair riders
  • SP2: side and rear impact protection
  • SP3: universal docking wheelchair securement
  • SP4: after-market wheelchair seating systems
  • SP5: wheelchair-integrated restraint systems
  • SP6: standards

SP-1

Slide 83: SP-1

Slide text:

  • Investigate the incidence, extent, and nature of injury to wheelchair riders due to motor- vehicle accidents,
  • Include recommendations for ways to minimize injury.
    • SP-1a: Survey Wheelchair Users re Accidents/Injuries.
    • SP-1b: Conduct In-depth Accident Investigations.
    • SP-1c: Perform Retrospective Investigation of Accidents/Injuries on Buses.

SP-2

Slide 84: SP-2

Slide text:

  • Investigate and report on safety issues, including both kinematics and biomechanics, related to wheelchair-seated occupants subjected to side and rear impact crashes.
    • SP-2a: Perform Biomechanics Review, Testing, and Development re Injury to WC-Seated Occupants in Rear Impacts.
    • SP-2b: Perform Biomechanics Review, Testing, and Development re Injury to WC-Seated Occupants in Side Impacts.

Graphic description:

Pictures of side impact and rear impact of a motor vehicle.

SP-2a:Rear-Impact Protection

Task Leaders: Manary/Schneider

Slide 85: SP-2a:Rear-Impact Protection Task leaders: Manary/Schneider Task Leaders: Manary/Schneider

Graphic description:

Graphics showing pre and post rearward impact of a wheelchair of which the wheelchair seat back failed.

SP-3

Slide 86: SP-3

Slide text:

  • Investigate, develop and evaluate a universal securement interface that would enable wheelchair and scooter users to safely and independently secure their wheelchairs and scooters to motor vehicles.
    • SP-3a: Investigate & Develop in Support of Universal Docking Interface Geometry (UDIG).
    • SP-3b: Develop & Evaluate Universal Docking Devices for Use in Low-G and Ultra Low-G Environments.
    • SP-3c: Develop & Evaluate Universal Docking Devices for Use in High-G Environments.

Graphic description:

Picture showing a wheelchair with an adapter (UDIG) mounted to the back.

SP-4

Slide 87: SP-4

Slide text:

  • Investigate and compare methods for static and dynamic testing of the crashworthiness of after-market and customized wheelchair seating systems
  • Develop strategies for integrating test methods into existing voluntary wheelchair performance standards.
    • SP-4a: Develop & Validate Test Methods to Evaluate Seating System Crashworthiness.
    • SP-4b: Develop Usage Guidelines & Design/Performance Criteria for Postural Support Devices.

SP-5

Slide 88: SP-5

Slide text:

  • Investigate, develop, and evaluate integrated occupant restraint systems that are independent of the vehicle and easy for wheelchair-seated occupants to operate.
    • SP-5a: Develop Usability Requirements for WC-Integrated Occupant Restraints (WIRS).
    • SP-5b: Develop Adult & Child WIRS Design Guidelines & Performance Criteria.
    • SP-5c: Develop & Evaluate Adult & Child WIRS Prototypes.

SP-6

Slide 89: SP-6

Slide text:

  • Investigate the use of new or existing voluntary performance standards related to:
    • wheelchair-seated occupants subjected to side and rear impact crashes, potential benefits of using integrated occupant restraint systems, universal securement interfaces, and after-market and customized wheelchair seating systems and peripheral devices.
    • SP-6a: Update Voluntary Standards.
    • SP-6b: Develop New Voluntary Standards.
    • SP-6c: Implement Completed Voluntary Standards.

Slide 90: Cartoon of a wheelchair occupant in a bus system

Graphic description:

Cartoon of a wheelchair occupant in a bus system. The occupant is restrained and secured with probably 20 cables, chains etc. to keep him and his wheelchair in place. The driver says before taking of: “everybody secure back there?”.

This is the end of the slide lecture.

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