WC19 - Wheelchairs Used as Seats in Motor Vehicles

Hello all!

This month, let's think about safety, wheelchairs, and transit. Individuals who remain seated in wheelchairs while travelling in vehicles are "45 times more likely to be injured in a crash than the typical passenger"^{1 (p. 2)}. The "typical" passenger in a vehicle transfers into the vehicle manufacturer's seat, which is secured to the vehicle, and uses the occupant restraint system; that is, the seat belt system that also is secured to the vehicle. Individuals who must remain seated in wheelchairs while travelling in vehicles also are at risk of injury in "non-collision events", such as sudden braking or sharp turning, resulting in the wheelchair tipping, securement failure, or the occupant falling out of the wheelchair^{1 (p. 4)}. Many individuals who must remain seated in the wheelchair during transit do not have postural control or the ability to stabilize themselves or their wheelchairs during these non-collision events, which can result in serious injuries.

The position paper on Wheelchairs Used as Seats in Motor Vehicles by the Rehabilitation Engineering & Assistive Technology Society of North America (RESNA) states that the "ideal" safety practice is for individuals who use wheelchairs to "transfer into a manufacturer-installed vehicle seat and use the vehicle's crash-tested occupant restraint system"^{1 (p.5)}. This is not always possible; for example, if a person is unable to safely transfer into a vehicle seat or requires the postural support provided by the wheelchair seating system. How can we promote safety for these individuals? Let's take a look at wheelchair transportation safety standards.

Wheelchairs Used as Seats in Motor Vehicles (WC19)

If a person must remain seated in a wheelchair while travelling in a vehicle, it is important that the wheelchair meets certain standards. "WC19 is a voluntary industry standard for designing, testing and labeling a wheelchair that is ready to be used as a seat in a motor vehicle. A WC19 wheelchair has:

• Four permanently attached and labeled securement points that can withstand the forces of a 30 mph, 20 g impact.
• Specific securement point geometry that will accept a securement strap end fitting hook.
• A clear path of travel that allows proper placement of vehicle mounted occupant safety belts next to the skeletal parts of the body,
• Anchor points for an optional wheelchair anchored pelvic safety belt, that is designed to withstand a 30 mph, 20 g impact, that has a standard interface on it that allows it to connect to a vehicle-anchored shoulder belt."²

What do these bullets mean?

Permanently Attached Securement Points

The four securement points on a wheelchair are the brackets installed on the wheelchair – two at the front of the wheelchair and two at the rear of the wheelchair – to which securement straps can be attached. The photograph below, to the left, illustrates the securement points on the front of a manual wheelchair. The photograph below, to the right, illustrates one of the securement points on the rear of a wheelchair. The hook symbol on the brackets is the required label that indicates that the wheelchair securement points conform to the WC19 standards. If the metal rings do not have the hook logo, it means that the wheelchair has not been crash tested successfully for occupant safety.³

The forces that the securements points must withstand – 30 miles per hour (or 48 kilometres per hour), 20 g impact – refer to the testing standards. Thirty miles per hour is the same standard that is used for testing passenger vehicles and child safety seats.⁴ When testing wheelchairs for WC19 compliance, the wheelchair is secured to a sled on a test track and an appropriately-sized crash test dummy is secured to the wheelchair. A frontal impact sled test is used in which there is a 30 mile per hour change in speed, simulating a frontal crash. A sudden change of speed of 30 miles per hour represents the 95th percentile of crash severity of frontal crashes of cars, minivans and SUVs.⁴ Therefore, most crashes in the "real world" will be less severe than the testing conditions.

Securement Point Geometry

The geometry of the securement point must allow for one-handed attachment of the hook of a tiedown strap when a driver or caregiver reaches for the securement points from one side of the wheelchair.¹ This means that the securement brackets are easily identifiable and easily accessible. In addition, when tiedown straps are applied to the securement points on the wheelchair and to the typical anchor points on the floor of the vehicle, the position of the straps should not be close to any sharp edges that could damage the strap material in the event of a crash.

Clear Path for Placement of Vehicle Mounted Occupant Safety Belts

A WC19 compliant wheelchair may be used with a wheelchair tiedown and occupant-restraint system (WTORS) in a vehicle. The occupant restraint part of WTORS is a three-point lap and shoulder belt. (More on WTORS in my next Clinical Corner article.) A WC19 compliant wheelchair allows for the easy passage of the shoulder belt, from the mounting in the vehicle and connecting to the pelvic belt near the hip of the wheelchair seated individual, without getting in the way. "The shoulder belt needs to be snug and positioned over the middle of the clavicle and across the sternum, and then connect to the pelvic belt near the hip"^{5 (p. 11)}. Wheelchair manufacturers are required to disclose the rating that each wheelchair model is assigned after undergoing independent testing with respect to accommodating the proper use and positioning of a vehicle anchored belt-restraint. The ratings are poor, acceptable, good, or excellent.¹

Anchor Points for a Pelvic Safety Belt

A pelvic safety belt is different than a positioning belt that is used for postural support in seating. Unless they have been labeled as having been crash tested, postural supports, such as positioning belts and chest harnesses, do not provide for restraint for an occupant seated in a wheelchair in a vehicle. In contrast, a safety belt is "a length of energy-absorbing webbing material used in occupant restraint systems."⁶ That is, a pelvic safety belt is specifically designed, tested, and labelled for crashworthiness. A WC19 compliant wheelchair has anchor points that allow for the installation of a pelvic safety belt that meets the testing standards and that can also accommodate the fastening of a vehicle-mounted shoulder belt, which forms the 3-point lap and shoulder belt occupant restraint of WTORS.

It should be noted that WC19 is a voluntary standard, which means that it has not been mandated by federal or provincial legislation. Many wheelchair manufacturers have their products tested in order to be WC19 compliant, however, not all wheelchairs have been tested or meet these standards. If a person will be using a wheelchair as a seat in a motor vehicle, or may in the future need to remain seated in a wheelchair during transit, it is important to consider the safety of the wheelchair at the time of prescription. If a product is prescribed that is not crashworthy, the rationale for its prescription "should be clearly documented to avoid possible confusion for parents and transporters over who made the final decision and why, if the lack of transit technology should result in injury"^{5 (p. 9)}.

There is a lot to consider when it comes to wheelchairs, seating, and transit safety. As I mentioned, the next Clinical Corner article will address WTORS. We will also look at WC20 – the standard for seating – in a future Clinical Corner article.

References

1. RESNA. (n.d.) RENSA's Position on Wheelchairs Used as Seats in Motor Vehicles. Retrieved from http://www.resna.org
2. Rehabilitation Engineering Research Center on Wheelchair Transportation Safety. (2010). The WC19 Information Resource: Crash-tested Wheelchairs & Seating Systems. Retrieved from http://www.rercwts.org/WC19.html
3. Fuhrman, S.I., Buning, M.E., & Karg, P.E. (2008). Wheelchair Transportation. Ensuring Safe Community Mobility. Retrieved from http://www.rercwts.org
4. Rehabilitation Engineering Research Center on Wheelchair Transportation Safety. (2008). Wheelchair Transportation Safety Frequently Asked Questions. Retrieved from http://www.rercwts.org
5. Shutrump, S.E., Manary, M., & Buning, M.E. (2008). Transportation for Students Who Use Wheelchairs on the School Bus. Retrieved from http://www.rercwts.org
6. University of Michigan. (2012). Ride Safe. A Glossary of Terms. Retrieved from https://wc-transportation-safety.umtri.umich.edu/