Project P3: Improved Design and Performance of Vehicle Restraint Systems for Frontal and Rear Impact Protection of Wheelchair-Seated Drivers and Passengers in Vans and Minivans

Task Leaders: Linda vanRoosmalen, Ph.D., Larry Schneider, Ph.D., Miriam Manary, MSE

Co-investigators: Nichole Ritchie, Nathaniel Madura, graduate students

Collaborators:  Jong-Bae Kim (wheelchair user) Pride Mobility (wheelchair manufacturer), Sure-Lok (WTORS manufacturer), Q'Straint (WTORS manufacturer), Creative Controls, Inc. (van modifier), Gresham Driving Aids (van modifier), A&A Driving School (school of driver trainers for the disabled)

Study Announcement and Consent Form

Overview

This project will address the long-term outcomes related to improved occupant protection and independence for wheelchair-seated travelers in personal vans and minivans. While both passengers and drivers are included in the scope, the primary emphasis will be on improving occupant restraint design and effectiveness for drivers, with a secondary emphasis on front-row passengers. The project will address front and rear-impact protection, primarily through improvements in the design of passive and wheelchair-integrated Wheelchair Tiedowns and Occupant Restraint Systems (WTORS).  However, it will also address issues of wheelchair design with regard to docking-type securement and with regard to accommodating the proper use and fit of WTORS.

The effort will be conducted over all five years of the RERC and is comprised of two primary tasks as follows:

• Task P3.1 - Investigation of WTORS Availability and Usage in Private Vehicles
• Task P3.2 - Development of WTORS for Improved Wheelchair User Restraint in Front and Rear Impacts of Private Vehicles

The project will begin with Task P3.1, an investigation of drivers and passengers seated in wheelchairs in their personal vehicles. The objective of this research effort is to more completely and objectively document the issues and problems surrounding the proper use of lap and shoulder belts, as well as frontal-impact airbags, by wheelchair-seated drivers and front-row passengers of private vehicles.

In years 2 through 5, the focus will shift to Task P3.2, a development task, which will be conducted in two phases. Part 1 will involve the development, demonstration, and evaluation of solutions for improving restraint effectiveness in frontal impacts. This work will be conducted in collaboration with wheelchair and WTORS manufacturers and van modifiers. It will involve the design and fabrication of innovative passive (no action required by the user) belt restraints for drivers, but it will also involve modifying existing powered wheelchairs so that they better accommodate the easy and proper placement of vehicle-anchored lap and shoulder belts.  This phase of the project will also include further evaluation and refinement of new concepts in seatbelt buckles developed in previous efforts, which allow people with disabilities to more easily don and doff vehicle- and wheelchair-anchored belts.  Issues related to improving both the operation and crashworthiness of forward-entry auto-engage docking stations for wheelchairs will also be addressed. 

In years 4 and 5, the effort will shift to Part 2 of Task P3.2, which will involve development relative to improving rear-impact protection for wheelchair-seated drivers and passengers, for which the level of occupant protection largely depends on the presence of effective head and back restraint. This part of the project will use the wheelchair geometry and rear-impact dynamic strength data collected in previous efforts to design and test a prototype, vehicle-mounted head/back support for use by wheelchair-seated drivers.

Expected Project Outputs and Short-term Outcomes

Expected Outputs

• Documentation and quantification of the issues and problems related to providing effective occupant restraint for wheelchair-seated occupants in private vehicles, with a particular emphasis on wheelchair-seated drivers,
• Workshops, conference presentations, and publications in peer-reviewed journals and consumer magazines that describe the problems and proposed solutions to providing more effective occupant restraint for drivers and passengers of personal vehicles in frontal and rear impacts,
• A WTORS standard with design/performance criteria and test methods for evaluating rear-impact protection,
• Prototype designs and demonstrations of new concepts for improved passive and active vehicle-anchored belt restraints,
• Demonstration of improved wheelchair and wheelchair seating system design features that provide for easier placement and improved fit of passive and active vehicle-anchored belt restraints,
• Evaluations of innovative buckle latching and release mechanisms for use by drivers and passengers with physical disabilities,
• Prototype designs for vehicle-anchored head and back supports that comply with the new TST standard, and
• Improvements in docking securement systems for wheelchair-seated drivers and front-row passengers

Expected Short Term Outcomes

• Safer and easier transportation options for occupants who use their wheelchairs as vehicle seats.

Project Updates

• Project P3.1: July 2007
• Project P3.2: July 2007
• P3 Annual Report 2007 (2.3 MB pdf)

Task P3.1: Investigation of WTORS Availability and Usage in Private Vehicles

In the first year of this project, a detailed investigation of the restraint conditions for wheelchair-seated drivers and passengers will be conducted to more rigorously identify the likely sources of the problems beyond what is known from current anecdotal cases. It will also evaluate the potential negative consequences of these belt-restraint configurations and compare the injury risk to that of occupants with proper belt restraint in frontal crashes.

This will not be a traditional hypothesis-driven research study with statistical sampling on independent variables, and it will therefore not attempt to use any traditional experimental design techniques.  The only sampling criteria are that subjects use a private modified van or minivan and that they drive or ride in those vehicles while seated in their wheelchairs. However, a particular emphasis in recruiting subjects will be placed on the wheelchair-seated driver for whom it is believed that:

• lap and shoulder belts are rarely used or positioned in a manner that will provide effective restraint for drivers in a frontal crash
• changes to the design of powered wheelchairs and vehicle-anchored belt restraints are needed to improve the routing and performance of belt restraints on wheelchair-seated drivers
• rear-impact protection systems are minimal to non-existent for wheelchair-seated drivers in private vehicles
• the proximity of wheelchair-seated drivers to vehicle hand controls and the removal of airbag restraint systems to allow installation of these controls further increases the injury risk for these occupants

The data collected in each measurement session will be aimed at answering several questions, including:

• Q1: What are common types of (modified) occupant restraints, wheelchair securement systems, and hand/steering controls used by wheelchair-seated drivers and front-row passengers of private vehicles?
• Q2: What are the factors contributing to improper fit and use of belt restraints to wheelchair-seated drivers and front-row passengers in private vehicles?
• Q3: What are the specific geometric relationships between front-row wheelchair-seated occupants, belt restraints, and the vehicle interior and controls?
• Q4: How do wheelchair-seated drivers and front-row passengers rate their experience with private-vehicle transportation with regard to safety, usability, and independence?
• Q5: What changes would wheelchairs users of private vehicles like to see to improve travel in their vehicles?

Data collection will involve the following three parts:

1. An interview with the participant
2. Video recording of the wheelchair user entering and exiting the wheelchair station, including securement of the wheelchair and positioning of belt restraints
3. Measurement and photographic documentation of the seatbelt, occupant, and vehicle interior geometry with the wheelchair and seatbelts in their usual positions

Update July 2007: P3.1 Investigation of WTORS Availability and Usage in Private Vehicles

A test protocol was developed, which includes forty questions and a checklist for observing and recording individuals while they enter, and position themselves in their vehicles while seated in their wheelchair. A comprehensive measurement tool including illustrations was developed for use during the subject testing. A flyer was developed to recruit 25 or more subjects in the Pittsburgh and Southeast Michigan areas. Subjects will be recruited from the Centers of Rehabilitation Services, the Center for Assistive Technology, Hyram G. Andrews Rehabilitation Center, and from local driver trainer organizations and vehicle modification programs.

IRB approval for the study has been obtained at Pittsburgh and is pending at the University of Michigan.

ADED and NMEDA have been targeted to obtain input from driver trainers as well as individuals that use their wheelchairs while driving/riding. These contacts have resulted in an invitation to present the issues of wheelchair-seated individuals in motor vehicles and to write an article in the ADED newsletter.

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Task P3.2: Development of WTORS for Improved Wheelchair User Restraint in Front and Rear Impacts of Private Vehicles

In Years 2 through 5 of this project, prototype devices and components that offer improved restraint effectiveness for front and rear impacts to wheelchair-seated drivers and passengers in private vehicles will be developed and evaluated in laboratory testing and in vehicle setups.  The focus of years 2 and 3 will be on occupant restraint systems for frontal crashes while the focus of years 4 and 5 will be on head and back supports for rear-impact protection.  As with the research effort of year 1, the primary focus will be on wheelchair-seated drivers, but passengers, particularly front-row passengers, will also be considered.

For improved frontal impact protection, the primary concerns are providing for improved fit of three-point belt restraints and allowing for increased use of frontal-impact airbags for wheelchair-seated drivers and right-front passengers.  Potential solutions that will be considered and explored include:

• Improvements in passive lap and shoulder belts that allow for easier and better fit to the driver or right-front passenger
• Modifications of powered wheelchairs to enable the easier and better fit of passive belt restraints
• Modifications to wheelchairs that provide for improved forward-moving and rearward-moving docking-type securement
• Improvements in wheelchair-integrated lap belts that provide for easier interface with a vehicle-anchored shoulder belt
• Refinements to prototype seatbelt buckles of vehicle-anchored lap belts
• Modification of vehicle hand controls to enable the use of frontal-impact airbags

For rear-impact protection, the primary concern is providing a properly positioned vehicle-anchored rear head restraint.  However, because most wheelchair backrests are not expected to provide effective back support in rear-impact loading, a vehicle-anchored back support must also be provided.  For drivers and front-row passengers, this will require a head-and-back restraint system that can be deployed after the occupant has moved into position, and removed when the occupant is ready to exit the vehicle, especially in emergency situations.  For example, a back and head support might be designed to automatically rotate up from the floor or down from the roof into contact with the wheelchair seatback in close proximity to the back of the user’s head after the driver’s wheelchair is secured in position. 

Along with the demonstration of a WTORS that provides enhanced protection in a rear-impact event, a draft WTORS standard will be developed that establishes test methods, design and performance criteria for these systems.  The standard will be harmonized with the other rear-impact standards and include a dynamic sled test at 16 mph and 8-10 g.  The design criteria will focus on the fit and proximity of the head/back support to the wheelchair user as well as its energy absorbing properties.  The performance criteria will focus on hardware integrity, allowed deflections, and control of the ATD movement.   The process of prototype development will enrich the standards process by demonstrating feasibility of meeting the criteria.

Update July 2007: P3.2

This project has not started.

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Last updated: December 4, 2007