SP-6: Investigate the Use of New or Existing Voluntary Performance Standards

Importance of the problem

Description of the need and target population

Both the Americans with Disabilities Act (ADA) and Federal Motor Vehicle Safety Standard 222 (FMVSS 222) include static load requirements for wheelchair tiedowns and occupant restraint systems and thereby include some provisions for the safety of wheelchair-seated travelers in public and school transportation. However, most of the progress over the past two decades toward improving occupant protection and transportation safety for wheelchair users who do not transfer to the vehicle seat has been made through national and international efforts to development voluntary recommended practices and standards (Schneider, 1996). The requirements for wheelchair securement in ADA apply only to public transit vehicles, and the requirements of FMVSS 222 apply only to wheelchair tiedown and occupant restraint systems (WTORS) installed by the original equipment manufacturer OEM) of the vehicle. Additionally, these federal standards require only static strength testing which does not account for strength the under dynamic loading that occurs in motor-vehicle crash environments (Stewart, 1981; Dong, 1981). In most cases, WTORS are after-market products that are purchased and installed after the vehicle has been purchased. Furthermore, neither ADA nor FMVSS 222 address wheelchair design and performance when used as a vehicle seat, thereby leaving a significant gap in the occupant-protection “system” for people who remain seated in their wheelchairs when traveling in motor vehicles. Finally, there is no federal standard that applies to private vehicles, such as modified vans and minivans, used by wheelchair-seated drivers and passengers.

As with other federal safety standards for motor vehicles, including FMVSS 222, crashworthiness safety standards for passenger motor vehicles, including the vehicle seats and occupant restraint systems, are established by the National Highway Traffic Safety Administration (NHTSA) (Dalrymple, 1990). Because of the relatively small size of the wheelchair-seated population compared to the population of vehicle-seated occupants, NHTSA’s limited resources for establishing safety standards, and the fact that NHTSA only establishes standards for OEM vehicles, this federal agency has declined to set safety standards for after-market wheelchair securement and occupant restraint systems in personal vehicles. Moreover, in 1992, the NHTSA declined a petition by a Michigan transporter of school children to address the design and performance of wheelchairs used for seating school buses, justifying this action, or lack of action, by the statement that wheelchairs are not “motor vehicle equipment.” (Transporting Students with Disabilities, Volume 5, Number 3, Feb. 11, 1994).

In the United States, efforts toward developing voluntary standards for WTORS began in the mid 1980s with the establishment of the Restraint Systems Task Force of the Society of Automotive Engineers (SAE) Adaptive Devices Subcommittee (ADSC). This Subcommittee and its various Task Forces were, in fact, the direct result of efforts by NIDRR to set up a mechanism for establishing requirements for the after-market equipment installed in vans that are modified for use by wheelchair-seated drivers and passengers. After more than ten years of effort, much of which involved working toward the developing of similar WTORS standards within the International Standards Organization (ISO 10542 series) as well as in Canada (CSA Z605), SAE J2249 Wheelchair Tiedowns and Occupant Restraints for Use in Motor Vehicles was approved and published as an SAE recommended practice in 1996. Comparable WTORS standards have now been completed in ISO and Canada, and today there are many WTORS on the market that comply with the requirements of these standards. During this time period from 1978 until the late 1990s, a significant amount of frontal sled-impact testing of WTORS was conducted at UMTRI and other laboratories, and the results of these tests have provided the basis for many of the requirements, procedures, and performance criteria contained in these initial standards (Schneider and Melvin 1978, Schneider et al. 1979, Schneider 1981, Benson and Schneider, 1984, Stewart and Reinl, 1981, Dong and Smith, 1981, Dalrymple 1990, Schneider, 1991)

Common to all of the WTORS standards is the requirement to dynamically test wheelchair tiedowns and associated occupant belt restraints using an 85 kg (187 lb) rigid surrogate wheelchair and a 76 kg (170 lb) midsize adult male crash dummy to load the tiedowns and restraints in a 30 m.p.h., 20-g sled impact test. This level of testing is patterned after tests required by federal safety standards for passenger vehicles (FMVSS 208; FMVSS 213) and, in that sense, is a “worst-case” (from a vehicle perspective) frontal-impact crash pulse. The use of this worst-case crash pulse in these initial WTORS standards has been based on the assumption that the WTORS manufacturer does not, and cannot, control the types and sizes of vehicles in which the WTORS equipment will be installed. It is important to understand, however, that SAE J2249 applies to WTORS that use all types of wheelchair securement systems, and does not specifically encourage or endorse any method of wheelchair securement. It does, however, require that a belt-type restraint system be included or specified by the WTORS manufacturer, and that occupant restraint must include both upper and lower torso restraints.

As SAE J2249 was nearing completion, it became clear to the members of the SAE Restraints Systems Task Force that the remaining weak link in the “system” to providing safe transportation to wheelchair-seated occupants of motor vehicles was the wide variety of wheelchairs that are called upon to function as vehicle seats, but that have not been designed or tested for that application. As a result, a new standards-development effort was initiated within the Wheelchair standards Subcommittee of ANSI/RESNA. The new Working Group, known by the acronym SOWHAT, for Subcommittee for Wheelchairs and Transportation, developed the first ANSI/RESNA transit wheelchair standard, Section 19 ANSI/RESNA WC/Vol. 1, in a record time of four years. Many of the participants in the development of this standard were the same as those who developed SAE J2249, and have also been working simultaneously to develop harmonized transit wheelchair standards in ISO (7176/19) and Canada (CSA Z604). Both Douglas Hobson and Larry Schneider played significant leadership roles in the development of the ANSI/RESNA, SAE, CSA and ISO standards.

Unlike the WTORS standards, the transit wheelchair standards require that a wheelchair provide four easily accessible securement points on the wheelchair frame, and that the wheelchair be dynamically tested in a simulated 30-mph frontal impact test while secured by a surrogate four-point strap-type wheelchair tiedown system. This is because the four-point, strap-type tiedown is the most commonly used method for wheelchair securement used by wheelchair passengers in public and private motor vehicles (i.e., it is today's universal securement system), and because compatibility between the wheelchair securement system in the vehicle and that provided for on the wheelchair is essential for effective wheelchair securement and occupant protection.

ANSI/RESNA WC/19 was completed in May 2000 and most wheelchair companies have been designing, redesigning, and testing many of their wheelchair models to comply with its requirements. Also, a closely harmonized ISO version of this standard is in the final voting stage (FDIS), and a comparable CSA standard has recently been revised to be more compatible with the ANSI/RESNA transit wheelchair standard.

Throughout these standard development efforts, and subsequent to the completion of these initial WTORS and transit wheelchair standards, one thing had become very clear. In the absence of a serious effort on the part of federal governments to establish safety regulations for wheelchair-seated travelers, the process of developing voluntary industry standards is one of the most important and effective ways to achieve real-world improvements in safety and crash protection for wheelchair users. Furthermore, the development of these standards on an international level has been a key factor toward achieving world-wide harmonization of requirements for WTORS and transit wheelchairs, and has greatly benefited manufacturers and consumers on a global basis.

It has also become clear that developing a voluntary standard that sets requirements for products is only the first step in getting products that conform to the requirements of the standard into the market place, and into the real world where they will benefit the wheelchair user and transportation providers. Once a voluntary standard has been completed and approved, a significant education and promotion effort is required to ensure effective interpretation and implementation of the requirements of the standards by manufacturers, primary users, clinicians, and others. In particular, because the impact of a voluntary standard is largely consumer driven, it is critical that wheelchair users, clinicians, and transit providers clearly understand the new standards and the benefits offered by products that conform to the new standards, in terms of reduced injury risk and increased operational efficiency. Only then, will they request, and even insist on purchasing, products that comply with these standards, and only then will the manufacturers be willing to design and test products to the requirements of the standards.

Finally, all standards need to be upgraded, improved, and enhanced as new information and data become available, and as experience with the test methods and criteria prescribed in the standards is acquired. Voluntary standards are developed by consensus using the best information available at the time, and need to be updated as new and more complete information becomes available, and as experiences from the real world suggests that adjustments are needed.

Beneficial impact on target constituency, including service providers

The results of the three tasks in this priority will directly benefit all wheelchair users who do not transfer out of their wheelchair when riding in or driving a motor vehicle. The results will also benefit the manufacturers of transit wheelchairs and WTORS, by providing clear design and performance targets for their products. Finally, the results will benefit transportation providers, including those involved in school, public-transit, and private transportation of wheelchair-seated occupants, by making effective wheelchair securement and occupant restraint easier, less time consuming, and more reliable.

Responsiveness to priority

The tasks in this section are in direct response the following NIDRR Priority: “Investigate the use of new or existing voluntary performance standards that would address the problems associated with wheelchair-seated occupants subjected to side and rear impact crashes and potential benefits of using integrated occupant restraint systems, universal securement interfaces, and after-market and customized seating systems and peripheral devices.”

Overall objectives

The specific aims of the tasks in this priority are three-fold and include:

  1. support the updating of national and international standards for WTORS and transit wheelchairs that have been developed to date,
  2. facilitate the development of new standards, or additional parts of existing standards, based on priorities established by standards groups and results of new research and testing, and
  3. facilitate the effective implementation of voluntary standards by working with product manufacturers, consumers, transportation professionals, and relevant federal and private groups, such as the VA and the PVA, to obtain support for, and ensure proper understanding and application of, the provisions and requirements of approved standards.

5 year report June 1, 2006

SP6a-c: Development, Updating, and Implementation of Standards

In the RERC on Wheelchair Transportation Safety, the development, updating, and implementation of voluntary equipment standards are critical activities for achieving the RERC’s long-term outcome or goal of improved transportation safety for wheelchair-seated travelers.  It is through the development and implementation of these standards that the results of RERC R&D activities are translated into the design, marketing, and use of real-world products that are required to provide wheelchair users with a reasonable level of transportation safety and crash protection.

For these reasons, RERC-WTS staff have worked throughout the past 4-1/2 years to provide leadership for the development and revising of both ISO and ANSI/RESNA standards.  In the ISO arena, RERC staff led the development and completion of ISO 10542-3 Wheelchair Tiedowns and Occupant Restraints with Docking Type Tiedowns, which includes the specifications for a Universal Docking Interface Geometry (UDIG). Also, the RERC-WTS staff have been leading the development of ISO 16840-4 Wheelchair Seating Systems for Use in Motor Vehicles, which includes a series of sled impact tests to validate the surrogate wheelchair base (SWCB) as a viable test device for conducting crashworthiness tests of wheelchair seating systems.  Finally, RERC staff have led the development of two New Work Items (NWI), including:


  1. a proposal to revise and upgrade ISO 7176/19 Wheelchairs Used as Seats in Motor Vehicles, which involved the development of a CD draft standard incorporating proposed changes and additions to the existing standard, and
  2. a proposal for a standard addressing rear-facing wheelchair stations in low-g, fixed-route transit vehicles.

Simultaneous with the ISO standards activities, RERC staff have continued to lead efforts to complete the first set of standards to be included in the initial volume of ANSI/RESNA Wheelchair Standards/Volume 4 – Wheelchairs and Transportation, including:

  • WC-18, which is the revised version of SAE Recommended Practice J2249 Wheelchair Tiedown and Occupant Restraint Systems for Use in Motor Vehicles based on experience using SAE J2249 for nearly ten years and including the UDIG,
  • WC19, which is the revised and updated version ANSI/RESNA WC19 Wheelchairs used as Seats in Motor Vehicles
  • WC-20 a new standard for Wheelchair Seating Systems for Use in Motor Vehicles, which is comparable to the ISO 16840-4 

In support of developing WC-20, validation testing of the SWCB was completed using four different commercial seating systems and a sling seat and seatback tested on both the SWCB and a commercial manual wheelchair.  Results of these tests confirm that testing of seating systems on the SWCB produces similar, but somewhat worst-case, seat and seatback loading and failures during frontal impact testing, and thus confirms that testing seating systems using the SWCB provides a viable method for evaluating seating system performance for use on a wide range of wheelchair bases.

In addition to these three standards, related documents that contain specifications and engineering drawings for test facilities have been updated for inclusion in Volume 4. These include:

  • the surrogate wheelchair (SWC),
  • the four-point surrogate tiedown systems (4-pt SWTORS),
  • the surrogate UDIG docking tiedown device (SUDIG WTORS), and the
  • surrogate wheelchair base (SWCB)

Finally, the results of Task 2a have been used to develop a draft wheelchair standard for rear-impact of forward-facing wheelchair seated occupants (RIFF), including preliminary test methods and performance criteria.  These requirements and test methods will be included in a separate part and future version of Volume 4.

With regard to the implementation of standards (Task 6c), there has been a significant effort throughout the past four years to develop and disseminate information that will inform and educate various interest groups about the existence of crashworthiness wheelchair and WTORS standards, and to answer questions from manufacturers and consumers about the standards and other issues related to safe transportation for wheelchair travelers.   In addition to numerous individual communications via email and phone conversations, and direct contact with numerous wheelchair and WTORS manufacturers through product testing to these standards at UMTRI, RERC staff have given numerous presentations and workshops and the RERC-WTS website has been updated with new information on standards activities and other educational materials.  In addition, the list of wheelchair products that comply with current ANSI/RESNA WC19 has been periodically updated.

A key tool for disseminating information about wheelchair transportation safety and encouraging the use of products that comply with the ISO and ANSI standards has been the Ride Safe brochure. This brochure was revised and updated during the past year and the updated version is now available on www.travelsafer.org.  Over 75,000 Ride Safe brochures have now been distributed and several wheelchair manufacturers are including them with all WC19 wheelchairs and distributing the brochures at trade shows and conferences.  

A significant step toward increasing the implementation of products that comply with the current standards was made in the development and discussion of the Theme-1 white paper at the RERC-WTS State-of-Science (Sos) Workshop held January 2005. The title of this theme was Barriers to the Development, Marketing, Purchase, and Use of Transit Safety Technologies, or TST, where the latter term refers generically to equipment that complies with voluntary WTORS and WC19 wheelchair standards.  

The discussions on this topic identified the primary barriers to increased availability of WC19 wheelchairs, which include:

  • A broad lack of knowledge and awareness of the standards and products that comply with the standards
  • Manufacturer’ fear of liability
  • Lack of economic incentives for manufacturers
  • The voluntary nature of the standards

Overall the top three strategies for dealing with all of the identified barriers to TST were:

  • Create regulations that make the presence and use of TST mandatory
  • Educate transit providers, third party payers, users, government agencies regarding the value of TST including the cost of injury vs. the cost of providing TST (i.e., cost benefit analysis)
  • Develop the concept that wheelchair transportation safety is an integral feature and therefore should be included into the base price of transit wheelchairs

In follow up to the SoS and these identified strategies, RERC staff have been actively involved in getting CMS codes assigned to most categories of powered wheelchairs to include reference to ANSI/RESNA WC19.  When the opportunity arises in the next few months, RERC staff will work to have WC19 referenced in CMS codes for both adult and pediatric manual wheelchairs.

Another important outcome of the SoS workshop resulted from a discussion with Dennis Cannon of the Transit-Access Board regarding opportunities to provide input with regard to changes to ADA requirements for wheelchair securement and occupant restraint in different types of public transit vehicles.  In response, a new Breakout Group of the RESNA Committee on Wheelchairs and Transportation (COWHAT) was formed and convened its first meeting in February to establish a plan for providing recommendations for changes to ADA that will improve both safety and efficiency in public transportation of wheelchair users.

In a further effort to reach constituent groups with information about transportation safety for wheelchair-seated travelers and standards for equipment used in transporting wheelchair users, formal connections between COWHAT and the National Mobility Equipment Dealers Association (NMEDA – i.e., the organization of vehicle modifiers for people with disabilities) and the American Public Transit Association (APTA) have been, or are the process of being, established.  Subcommittees established within these organizations will provide the means for these constituent groups to interpret and disseminate information on the standards and related best practice as appropriate to their respective transportation environments, as well as for providing input to the development of future standards and revisions of existing standards. In addition, RERC staff have continued to maintain contact with national organizations that oversee school transportation safety and recently provided revisions to the section of the National School Transportation Specifications and Procedures manual dealing with “Specially Equipped School Bus Specification.”


Last updated: July 11, 2006