Wheelchair Crash Test Results

Original Information from This Rehabilitation Engineering Research Center (RERC) on Wheelchair Transportation Safety

Standards for Wheelchair Transportation Safety have been developed by ANSI/RESNA and ISO, which are US and International standards organizations. These standards require that any wheelchair securement system, occupant restraint system or manual/power wheelchair successfully pass a 30mph/20g impact sled test.

The manufacturer of the device takes responsiblity for working with the testing facility to meet the requirements for the the sled test. (Read about the testing process at the University of Michigan Transportation Research Institute.)

Only when a transit safety technology has successfully passed a sled test can the manufacturer claim that their device complies with the transportation safety standard. These standards describe in great detail how products are to be designed, tested, and labeled. (You can read more about standards on standards section of this website or purchase a copy of the standards from RESNA.)

For the novice, let’s translate the “30mph/20g” criteria. It means that the wheelchair with it’s transit safety technology and it’s crash test dummy occupant are exposed to a simulated front-end collision. The wheelchair and the dummy experience a 30 mile per hour change in velocity and a deceleration equal to 20 times the force of gravity.

In real life, for a wheelchair rider weighing 180 pounds (81.6 kg) this creates a huge amount of force. Twenty g’s acting on 180 lbs of weight translates into a force of about 3600 lbs. (Imagine trying to catch a 3600 lb beach ball!)

This “30mph/20g” crash criteria is the same criteria that is used in testing all automobiles and child restraints or car seats. Using this same criteria when testing wheelchair transportation safety technologies is intended to provide equivalent protection for wheelchair riders.

Use the series of videos on the following pages to educate yourself about the value of transit safety technologies. Each crash test videos shows the contribution of one aspect of transportation safety technology–wheelchair securement, occupant restraint or the use of a WC19-compliant wheelchair. The crash tests were conducted in the test facility at the University of Michigan Transportation Research Institute (UMTRI).

The best choice for any traveler is to transfer to the vehicle seat and wear the vehicle’s passenger safety belts. However, when transferring to a vehicle seat is too risky or is not possible, a person riding seated in a wheelchair should use all three parts of the transit safety technology to create optimal transportation safety.

Wheelchair Securement

All four straps are needed to secure the wheelchair to the floor of a vehicle. This method is most often used in transit buses, paratransit buses, school buses and in personally-owned vans. It works well in these settings because the straps work with many types and styles of wheelchairs. The standard for testing the strength of the securement of the wheelchair to the floor of the vehicle with straps or a docking system is comparable to the standard used for testing the attachment of a car or bus seat to the frame of the vehicle.

The objective of 4-point securement is to attach the straps to the wheelchair frame just below the combined center of mass of the wheelchair and it’s occupant. The angles from the floor to the wheelchair are carefully defined within the standard so that they stabilize the chair and prevent tipping, rotation and forward movement.

It is important to use all 4 straps. Some bus drivers, transit aids or passengers might consider attaching only the straps that are the easiest to reach. Not using all 4 straps places too much of a load on the straps that are used and may also lead to tipping.

The following videos show various scenarios such as failing to use securement or using only one front and one rear strap. The final video shows the use of all 4 straps.

This is a 30mph frontal impact test of an unsecured and unoccupied surrogate wheelchair.

This is a 30mph frontal impact test of an unoccupied surrogate wheelchair secured by four tiedown straps.

Three-point Occupant Restraint

After the wheelchair is secured to the floor of the vehicle, the next goal is to keep the wheelchair rider in the wheelchair. Most vehicle-related deaths and injuries happen in secondary impacts such as when the occupant hits the inside of the vehicle or is ejected from it.

Only the bony parts of the body can withstand the forces exerted against the body by the occupant restraint. A 3-point occupant restraint acts like the seatbelt in a car. The pelvic portion of the best goes low and snug across the pelvis.

The chest portion comes from the vehicle wall and crosses the collar bone and breast bone to anchor in at the pelvis. If the occupant restraint does not cross bony areas, significant injury to soft tissue can occur.

It is important to use all 3 parts of the restraint. All vehicles should have a means to modify the origin point of the chest strap on the vehicle wall. The adjustability of this origin point allows the torso restraint belt to fit either a tall or short person.

Just because a wheelchair has a “seatbelt” with an automotive or airline style buckle does not mean that this belt is a safety belt. Most positioning belts are NOT anchored to the frame of the wheelchair. They are simply screwed into the seat rails.

The following videos use a surrogate wheelchair (a wheelchair designed for repeated crash-testing) to demonstrate the contribution of 3-point occupant restraint.

  1. The first video shows the consequences of using no securement at all. This gives a clear visual of the meaning of the phrase: “secondary impacts.”
  2. The second shows the consequences of using after market positioning devices such as butterfly harnesses, hook and loop belts, etc.
  3. The third shows the extreme movement of the upper torso that happens when only the pelvic portion is used. It does however, prevent secondary impacts.
  4. The fourth video shows the extreme movement that happens when only the shoulder/chest portion is used. This movement, called “submarining,” can lead to significant injury to the internal organs or obstruction of the airway.
  5. The final video shows the protection offered by a properly positioned, 3-point occupant restraint.

Using NO wheelchair occupant restraint

This is a 30mph frontal impact test with no occupant belt restraints.

Using only “postural support devices”*

*e.g., chest harnesses, straps with hook & loop fastener, or after market pelvic belts.

This is a 30mph frontal impact test using only postural-support belts.

This is a 30mph frontal impact test using only a vehicle-anchored pelvic belt restraint.

Using an occupant restraint belt that travels over the armrest of the wheelchair instead of snugging against the body.**This allows the motion called “submarining” which has the potential to cause life-threatening injuries to the internal organs, neck and airway. This is a 30mph frontal impact test using a vehicle-anchored three-point belt restraint with the pelvic belt placed over the wheelchair armrests.

Using a properly fitting 3-point occupant restraint.This is a 30mph frontal impact test using a properly positioned, vehicle anchored, three-point belt restraint.

Using a WC19 Compliant Wheelchair

The WC19 compliant wheelchair is the newest part of transit safety technology. This ANSI/RESNA standard, passed in April 2000, describes a wheelchair that can withstand the forces of a crash. This American standard for transit tested wheelchairs is similar to ISO and Canadian standards.

After the wheelchair is secured to the floor of the vehicle, and the wheelchair passenger is belted using safety restraints, the next goal is to seat the passenger in a wheelchair designed to be a seat in a motor vehicle. Many wheelchairs do NOT have suitable points for attaching straps. Other wheelchairs do not allow attachment at the correct height on the wheelchair frame. The vehicle driver is left to guess the best location.

Still other wheelchair frames are not strong enough to withstand the forces of a sled test crash pulse. Just because a wheelchair has a “seatbelt” with an automotive or airline style buckle does not mean that this belt is a safety belt.

Most positioning belts are NOT anchored to the frame of the wheelchair. They are simply screwed into the seat rails. Velcro and positioning belts with buckles offer inadequate crash protection under high loads.

If a wheelchair is labeled as WC19 compliant, it means that this wheelchair model is available with a crash-tested frame and transit hardware and a wheelchair anchored safety belt.

The wheelchair, when configured with these options, is sled tested with the appropriate size of test dummy as the standard requires. This website has an up-to-date, complete listing of WC19 compliant wheelchairs.

The WC19 standard is intended to insure that a wheelchair is more easily secured and the occupant is more easily restrained. These features makes it easier to comply with the first two parts of the transit safety technology system; the 4-point wheelchair securement and 3-point occupant restraint.

The following videos demonstrate the contribution of a WC19 wheelchair:

  1. The first video is a non-WC19 compliant wheelchair.
  2. The second video is an adult in a WC19 compliant power wheelchair.
  3. The third video is a child in a WC19 compliant manual wheelchair.
  4. The fourth video is a child in a WC19 compliant power wheelchair

A sled test with a non-WC19 compliant manual wheelchair.

This is a 30mph frontal impact test with a non WC19-compliant manual wheelchair and an adult crash-test dummy (ATD) restrained by a vehicle-anchored, three-point belt restraint.

This is a 30mph frontal impact test of a WC19-compliant powered wheelchair and an adult crash-test dummy (ATD) restrained by a vehicle-anchored, three-point belt restraint.

This is a 30mph frontal impact test of a WC19-compliant stroller wheelchair and a 6-year old crash-test dummy (ATD) restrained by a vehicle-anchored, three-point belt with wheelchair-anchored pelvic belt restraint.

A sled test with a child in a WC19 compliant power wheelchair.

This is a 30mph frontal impact test of a WC19-compliant pediatric powered wheelchair and a 6-year old crash-test dummy (ATD) restrained by a vehicle-anchored, three-point belt restraint.

Original Information from This Rehabilitation Engineering Research Center (RERC) on Wheelchair Transportation Safety

 

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