RESNA WC-4:2012, Section 18 -
Wheelchair Tiedown and Occupant Restraint Systems (WTORS) for Use in Motor Vehicles
WC18 is a revised and updated version of SAE J2249, Wheelchair Tiedown and Occupant Restraint Systems for Use in Motor Vehicles. The standard was published in December 2012 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. The standard is available for purchase at the RESNA American National Standards webpage or by contacting RESNA:
RESNA, 1700 N. Moore St, Suite 1540, Arlington, VA 22201-1903
WTORS that comply with WC18 are labeled with the symbol below.
To download a high resolution version of the Volume 4 Wheelchair Transportation Safety symbol click here:
Rationale for the Standard
For people with disabilities who are not able to safely transfer from their wheelchairs, including three- and four-wheeled scooters, when traveling in motor vehicles, the wheelchair must serve as the vehicle seat. This usually means that the belt-restraint system installed by the vehicle manufacturer (i.e., the OEM belt restraint) cannot be used to provide protection in a crash. In addition, the wheelchair must be effectively secured to the vehicle so that its mass does not add to restraint forces on its occupant and/or become a hazard to other vehicle occupants in a collision or sudden vehicle maneuver. Providing occupants seated in wheelchairs with adequate transportation safety and crash protection therefore requires the installation of equipment in vehicles to provide these travelers with the opportunity for effective wheelchair securement and occupant restraint during normal and emergency vehicle operation and crash situations.
The goal of RESNA WC-4:2012, Section 18, which is a revised and updated version of Society of Automotive Engineers (SAE) Recommended Practice J2249: Wheelchair Tiedown and Occupant Restraint Systems for Use in Motor Vehicles, hereafter referred to as “WC18,” is to encourage and promote the design, testing, installation, and use of wheelchair tiedown and occupant restraint systems (WTORS) that will provide effective frontal-crash protection for forward-facing occupants in wheelchairs comparable to that provided by OEM occupant-protection systems that must comply with federal motor vehicle safety standards (FMVSS). The primary purpose is to reduce the likelihood of serious and fatal injuries to occupants seated in wheelchairs who are involved in frontal vehicle crashes. However, use of equipment that complies with this section of RESNA WC-4 will also result in increased safety and security for occupants seated in wheelchairs during normal travel, emergency vehicle maneuvers, and other types of crashes, such as vehicle rollovers and side impacts.
The provisions of WC18 are based on the premise that WTORS manufacturers are generally not able to control the end use of their products and the vehicles in which they are installed. WC18 therefore requires crashworthiness evaluation of WTORS for general use in all types and sizes of motor vehicles by conducting a nominally worst-case 48 kph (30 mph) frontal sled-impact test using an 85 kg (185 lb) surrogate wheelchair (shown in the photo to the left and detailed in the engineering drawings here) and a midsize adult male anthropomorphic test device (ATD), or crash-test dummy, with a nominal mass of 78 kg (172 lb) to dynamically load the wheelchair tiedown and occupant restraint system, respectively. For vehicles with a gross vehicle weight (i.e., the fully loaded weight) greater than 5,000 kg (11,000 lb), it may be appropriate to qualify WTORS using a lower crash severity than is required by this standard because of the reduced likelihood of heavier vehicles being involved in severe impacts.
WC18 requires that every WTORS include a belt-type occupant-restraint system with both a pelvic belt and one or more shoulder belts since the evidence is clear that the combination of upper- and lower-torso belt restraints is the most effective method of reducing injuries and fatalities in a wide range of crash conditions, including frontal crashes, vehicle rollovers, and a large percentage of side impacts. In addition, belt restraints can be easily implemented in most forward-facing seating positions of passenger vehicles. However, this section of RESNA WC-4 allows for, and applies to, WTORS that use different approaches to wheelchair tiedown, including four-point, strap-type tiedowns, and docking securement devices.
To address the expectation that an increasing number of occupants seated in wheelchairs that comply with RESNA WC-4:2012, Section 19 will be using a wheelchair-anchored pelvic-belt restraint, it is important for wheelchair tiedown/securement systems to be able to withstand the additional occupant restraint loads that will result from this belt-restraint condition. For this reason, this section of RESNA WC-4 requires that, beginning December 2015 (three-years from the date of publication), two frontal impact tests must be conducted for WTORS that provide a complete three-point belt restraint with a vehicle-anchored pelvic-belt restraint and that are intended for general use. The first test evaluates the complete WTORS with the vehicle-anchored belt restraints and is effective upon publication of this section of RESNA WC-4. The requirement to conduct a second test becomes effective three-years after the publication of RESNA WC-4:2012 and evaluates the dynamic strength of the tiedown/securement system when occupant-restraint loads are transferred though a wheelchair-anchored pelvic belt to the wheelchair and the tiedown/securement system.
Scope of Standard
This standard applies to WTORS comprised of a system or device for securing or tying down wheelchairs, including three- and four-wheeled scooter wheelchairs, and a system of belts for restraining occupants seated in wheelchairs. It applies to complete WTORS in which all components are provided by the WTORS manufacturer, but it also applies to WTORS that are completed by using portions of belt-restraint systems provided by the vehicle manufacturer (i.e., OEM belt restraints), particularly for people who drive while seated in their wheelchair.
WC18 applies to WTORS designed for use with a wide range of wheelchairs and their occupants, as well as to WTORS designed for limited use with a specific wheelchair model and/or occupant size range. It applies only to WTORS intended for use with forward-facing wheelchair-seated children and adults with a body mass of 12 kg (26.5 lb) or more who are traveling as passengers or drivers in private, paratransit, public, and school vehicles. It applies to WTORS that use all types of wheelchair tiedown and securement methods, but it only applies to WTORS that include both upper- and lower-torso belt-type occupant restraints.
WC18 specifies design requirements and performance requirements and associated test methods for WTORS, as well as requirements for product labeling and manufacturer literature, including presale literature, instructions to installers and wheelchair users, and placards for installation in vehicles at wheelchair stations. The key design and performance requirements apply to all types of WTORS but some requirements are specific to WTORS that use a particular type of wheelchair tiedown/securement system, such as the four-point, strap-type tiedown or a docking securement device.
WC18 places particular emphasis on the dynamic strength of WTORS in a 48 kph (30 mph) frontal-impact sled test, but it also includes requirements and test methods for achieving proper and effective use of WTORS on different size occupants in different types of wheelchairs, for ensuring effective engagement of WTORS components, and for webbing slippage at adjustment mechanisms of strap-type tiedown assemblies. It also establishes specifications for universal docking interface geometry (UDIG) for wheelchairs and wheelchair securement adaptors with the ultimate goal of providing for docking-type wheelchair securement in public and paratransit vehicles that must accommodate a wide range of wheelchairs.