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Seated Devices for Use in Motor Vehicles

WC-20, Seating Devices for Use in Motor Vehicles, is currently under development as a new standard (adapted from the draft ISO 16840-4 standard). The standard will be published as part of the American National Standards Institute/Rehabilitation Engineering and Assistive Technology Society of North America (ANSI/RESNA) Wheelchair Standards/ Volume 4: Wheelchairs and Transportation. For the latest information on the progress of this development, consult the RESNA Technical Standards Board webpage.

Rationale for Standard

Many wheelchair users remain seated in their wheelchairs while traveling in motor vehicles. Under these circumstances, the wheelchair and seating system plays a important role in protecting the occupant in a crash. The wheelchair and its seating system must provide a stable support surface under normal driving maneuvers, as well as crash conditions. The seating system should reduce the likelihood of “submarining” under the pelvic belt, as well as maintain the occupant’s position in a crash to promote effective occupant restraint. Wheelchairs and seating systems that are not designed to withstand crash level forces place their occupants at an increased risk of injury in a crash.

ANSI/RESNA WC19 defines requirements for wheelchairs, including their seating systems, which are intended for use as motor vehicle seats. However, seating systems are often provided as after-market products, independent of a wheelchair frame. Therefore, requirements must be defined for seating systems alone, independent of a specific wheelchair frame. Such requirements are defined in ANSI WC 20/Volume 4, Seating Devices for Use in Motor Vehicles.

All types of seating systems, including specialized seating systems, are included in this standard. For the purposes of WC20/Vol 4, a complete seating system consists of a seat pan, seat back and attachment hardware. The seating system may, or may not include postural support devices. The current version of WC 20/Vol 4 includes seating systems that may incorporate pelvic belt anchorages on the seating system, but does not include seating systems with shoulder/upper torso belts anchored to the seating system at this time.

Additionally, WC20/Vol4 does not include seating systems that incorporate tiedown anchorages. WC 20 sets forth design and performance requirements and associated test methods for seating systems used in forward facing wheelchairs intended to serve as motor vehicle seats. The dynamic test requirements specified in WC 20/Vol 4 are representative of a 48kph/20g frontal impact. This dynamic test is conducted using a surrogate wheelchair base that is able to accommodate a variety of types and sizes of commercial seating systems. During the test, the surrogate wheelchair base is secured using 4-point surrogate tiedowns, while the occupant is restrained using a 3-point occupant restraint system. The occupant, represented by an anthropomorphic test device (ATD) in the dynamic test is selected according to the intended occupant weight usage guidelines established by the seating manufacturer. WC20/Vol 4 also includes a test for the seating system’s accommodation of vehicle-anchored occupant restraints. Since occupant restraint positioning is key to effective protection, seating systems will be evaluated and rated based upon their level of accommodation of vehicle-anchored occupant restraints.

Scope of Standard

This standard specifies design and performance requirements, and test methods for seating systems intended for use with a manual or powered wheelchair, and indicates the suitability of the seating system for occupancy by adults or children over 22 kg when transported in their wheelchair forward facing in all types of motor vehicles. Seating systems that comply with this standard are intended to be used with wheelchair bases that have been successfully tested to WC19 requirements. This standard applies only to wheelchair seating systems, including attachment hardware, that are designed to be used with tiedowns that attach to the wheelchair base. The pelvic restraint portion of the occupant restraint may anchor to the seating system, the wheelchair base, vehicle or tiedown system, while the upper torso restraint must anchor either to the vehicle, the wheelchair base or the tiedown system, but not the seating system. It also specifies labeling, installation instructions, user instructions and warnings for the seating system manufacturer.

Last updated: August 11, 2008


Department of Education, Washington DC
This Rehabilitation Engineering Research Center (RERC) on Wheelchair Transportation Safety
is funded by NIDRR grant #H133E060064

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