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Frequently Asked Questions

Wheelchair Transportation Safety

Frequently Asked Questions (FAQs)

A FAQs forum intended for wheelchair users, parents, and practitioners concerned about wheelchair transport safety

Complied by: Douglas Hobson and Larry Schneider

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Question List

Last addition: May 25, 2001

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Question 1: What are the main safety concerns for someone seated in wheelchair while in a motor vehicle?

Answer:
First, let's think about the some of the primary injury prevention features that are used in family vehicles, i.e. cars, vans and SUVs. First, the seats are firmly anchored to the floor, and they are designed and positioned to minimize occupant contact with the vehicle interior in the event of a frontal collision, when combined with a properly located occupant restraint. More recently, the above safety system has been supplemented by rapidly deploying airbags. In this way, the design of seat, occupant restraint airbags and vehicle combine to form a safety system that in most cases will allow the occupant to safely “ride-down” the high impact forces that occur during many typical motor vehicle accidents. In general, given all other factors being equal, the larger the vehicle the lower the impact forces. For example, statistically it is highly unlikely that a person seated in large urban bus will experience high impact loads, simply due to the mass of the vehicle in which they are riding.

On the other hand, typical wheelchairs are not designed to be used as seats in motor vehicles. The wheelchair frames and seats are generally not strong enough to withstand the impact loads that can result under crash conditions. Unless properly secured to vehicle (as are vehicle seats) they will not prevent the occupant from coming into contact with the interior of the vehicle or other passengers. For effective occupant protection the restraint system must fit well to the body, especially over the pelvis and upper trunk. Most wheelchairs prevent a good fit of the occupant restraint due to the location of arm rests, push wheels and seat frame members, etc. Location of the fixed upper restraint anchor points, usually on the wall of the vehicle between windows, also may prevent the appropriate fit of the occupant shoulder belt, especially if it is a “one size fits all” design.

Crash research has shown that the orientation of the wheelchair in the vehicle, sideways or forward facing, also has significant safety implications. When side facing the wheelchair (and the person) are in the worst orientation in the vehicle in a frontal crash, which is the direction of impact in excess of 50% of vehicle accidents. Forward or rearward facing is therefore the orientation that all occupied wheelchairs should be in during vehicle transport.

The strength of tiedown (securement) devices and how they are fastened to the wheelchair is also an important consideration. For example, attachment of tiedown straps to footrests or armrests that are detachable will not withstand a crash event.

Trays and tray-mounted accessories, such as laptop computers or communication devices, are rarely fixed to wheelchairs in a manner necessary to minimize the chance of injury. It is therefore recommended that these devices be stowed elsewhere during transport.

And finally, the quality and availability of information to installers and users of tiedowns is critical to the proper installation and use of these products.

Clearly, the years of automotive crash safety research that has made our motor vehicles safer over time is only now being extended to people who either must or prefer to use motor vehicle transportation while seated in their wheelchairs. In most cases, transfer to the vehicle seat, especially when a crash-tested occupant restraint is installed by the original manufacturer, will offer the highest level of occupant protection. For those remaining in their wheelchairs, they will be at increased risk of injury for the reasons suggested above, unless some additional steps are taken to implement the proven safety features used in automotive injury prevention systems.

For more information on the crash biomechanics and wheelchair transport safety see:
RPJ2249-Application Guidelines (ever. June, 1999)

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Question 2: What steps are being taken to improve injury prevention for wheelchair-seated vehicle users?

Answer:
It was not long ago, mainly for liability reasons, that wheelchair manufacturers were placing stickers on powered wheelchairs that stated, ”not to be used as a seat in a motor vehicle”. Creating major change in industry-wide practice is not a simple task, especially if cost is involved.

The approach taken has been to use industry technical standards, both national and international, as means of bringing the key players to the table, including industry designers, researchers, clinicians, transporters, school transportation administrators and wheelchair users. One well recognized standards-setting organization in the U.S. is the American National Standards Institute (ANSI). At the international level, the International Standards Organization (ISO) sets technical standards on a world-wide scale. ANSI serves as the US representative on ISO committees. Within the US, ANSI has assigned standards development authority to the Rehabilitation Engineering and Assistive Technology Society of North America (RESNA). RESNA committees have been working on the development of wheelchair standards, in general, since the early 1980s, and more specifically on transport concerns since the early 90’s. The RESNA Subcommittee on Wheelchairs and Transportation (SOWHAT) completed the WC-19: Wheelchairs Uses as Seats in Motor Vehicles standard in April 2000.

The Society of Automotive Engineers (SAE) has long been the coordinating organization regarding automotive technology and industry standards. Since the late 80s, SAE has had 4-5 working groups working on a variety of automotive-related wheelchair standards, one being the Wheelchair Restraints Task Group. It is that group that developed SAE J2249, Wheelchair Tiedown and Occupant Restraints, which was completed in 1997.

Typically a standard takes from 5-8 years to take from conception to completion. Standards must be reviewed and if necessary, revised every five years. Three main areas of transport safety have received attention: 1) devices for securing a wheelchair to the vehicle, 2) the structural design of a wheelchair to be used for transport, and 3) the structural design of the transport wheelchair seat. The first generation ANSI/RESNA and ISO standards for the areas 1) and 2) are now complete. The third area, 3) is still in its early phase of development. The resulting industry standards are voluntary. Virtually all wheelchair securement products now sold in the US will have successfully passed one or more securement device standards (SAE or ISO). Currently, (2001) there are approximately ten wheelchair products on the market that comply with the ANSI/RESNA WC-19, Wheelchairs Uses as Seats in Motor Vehicles. For more information on these products click on the following URL.

For more information on these products, contact your local wheelchair supplier or wheelchair manufacturers. The following manufacturers have actively participated in the development of safer wheelchair transport products.

Wheelchair Securement Products

Adaptive Equipment Systems

Tom Novotny

800-237-2370

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Question 3: Is there a difference between the content of the U.S., Canadian and ISO wheelchair transport standards?

Answer:
The current wheelchair transport safety standards were developed at slightly different times at the national and international levels, therefore with varying degrees of harmonization. However, the basic principles and test procedures for all the standards are based on those used in the automotive industry, therefore the similarities far exceed the differences. The Canadian effort, under the auspices of the Canadian Standards Association (CSA), was completed first and unfortunately with relatively little collaboration with the US or ISO efforts.

The following is a listing of the various standards and completion dates in Canda, USA and ISO:


Canada:
Z604: Transportable Mobility Aids -(Feb., 1997)
Z605: Mobility Aid and Occupant Restraint –(Feb., 1997)
As of March 2001, both Z604 and Z605 are under revision which should help to align them more closely with the US and ISO counterparts.

U.S:
The ISO standards were developed with strong participation from the US, therefore the harmonization between the US the ISO efforts are much closer.
At present, the completed US and ISO standards are as follows:

SAE J2249 (WTORS): Wheelchair Tiedown and Occupant Restraint Systems-(January-1997)
SAE J2252: Mechanical Drawings for the Surrogate Test Wheelchair (January-1997)
ANSI/RESNA WC-19: Wheelchairs Used as Seats in Motor Vehicles (April-2000)

As of March 2001, both SAE J2249 and J2252 are under revision. This should increase harmonization with there more recently completed ISO counterpart. Also, the approach taken in the US was to develop one all encompassing standard for wheelchair tiedowns and occupant restraints, whereas in the ISO, the approach has been to develop five interrelated parts as indicated below.

ISO:
10542-Part 1: Wheelchair Tiedown and Occupant Systems- General requirements and test methods for all systems (Spring-2001)
10542-Part 2: Wheelchair Tiedown and Occupant Systems- Four point strap-type tiedown systems (Spring-2001)
The current plans call for the ISO 10542 standard to ultimately contain five parts:
10542-Part3: Wheelchair Tiedown and Occupant Systems-Docking Systems (2003) 10542-Part4: Wheelchair Tiedown and Occupant Systems-Clamping Systems (2002)
10542-Part5: Wheelchair Tiedown and Occupant Systems-Systems for Specific Wheelchairs (2002)

ISO 7176-19 Wheelchairs: Wheelchairs for Use in Motor Vehicles (Summer, 2001)
ISO 16840 Wheelchairs seating: Seating Devices for Use in Motor Vehicles (2003)

The overall goal has been to have harmonization of standards across the world through working cooperatively within ISO. The value of this approach is that wheelchair transport products will be able to flow across borders without the barriers caused by differences in national or regional standards. To a large extent this is being achieved, as the key performance requirements, labeling and test methods are to a large extent identical in all countries.

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Question 4: Where can I get more detailed information about the activities of the standards working groups (draft standards, meeting minutes, reference documents, etc.)?

Answer:
The University of Pittsburgh RERC maintains a WWW-site that tracks the activities of the wheelchair transport and seating standards development efforts. This may be found by directing your Netscape or Navigator browser to :

http://www.wheelchairstandards.pitt.edu/

Then scroll to:
ANSI/RESNA-SOWHAT-WC-19: Wheelchairs Used as Seats in Motor Vehicles
SAE-J2249: Wheelchair Tiedown and Occupant Restraint Systems
ISO- 10542: Wheelchair Tiedown and Occupant Restraints
ISO-7176-19: Wheelchairs for Use in Motor Vehicles
ISO- 16840-4: Seating Devices for Use in Motor Vehicles

Within each organization you can also download a copy of meeting minutes, the latest draft standard prepared by the working group, or in some cases, copies of specific reference documents.

You will need a copy of Adobe Acrobat on your computer to open the file that is downloaded to your computer, since it will be in the .pdf format. If you don't already have one, you can get a free copy of Acrobat from Adobe.

For more information on these products, contact your local wheelchair supplier on wheelchair manufacturers.

Wheelchair Securement and Transport Products


Name Contact person Phone number
Adaptive Equipment Systems
Convaid, Inc.
Everest & Jennings
Freedom Designs
Invacare
Metalcraft Industries, Inc.
Patron
Pride Health Care, Inc.
Snug Seat, Inc.
Sunrise Medical HHG, Inc.
Tom Novotny
Gina Wornson
Ruth Lytle

Lee Sheffield
Bob Jones

Jim Mulhern
Kirk Mackenzie
Steve Lindquist
800-237-2370
310-618-0111
905-669-2381
800-333-6900
800-329-6394
608-835-3232
877-330-1510
717-655-5574 x155
800-336-7684
303-218-4420

The following manufacturers have actually participated in the development of safer wheelchair transport products:

Wheelchair Tiedown and Occupant Restraints
Kinedyne Corp. – Bob Joseph
Q’Straint – Jean Marc Girardin
Ortho Safe Systems – Winnie Kraft
New Haven Equipment – Ray Lee


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Question 5: What are the general requirements for all products that conform to the wheelchair transport standards?

Answer:
Since the overall goal of the standards efforts is to provide a level of transport safety equivalent to non-wheelchair users seated in motor vehicles, the basic principles and test procedures parallel those of the automotive industry. As a result, all the standards contain essentially equivalent general design, labeling, information disclosure and performance requirements that may be summarized as follows:

Design: specifies the design features that a product (tiedown, occupant restraint or wheelchair) must have to carry out its intended function.

Labeling: specifies the labels that must be affixed to a product to disclose that it conforms to the standard or will permit ready identification of the model and manufacturer in the event of a product recall.

Information disclosure: specifies the nature of the information that most be made available to the installer or user of the product. This includes presale literature, product maintenance information, hazard warnings, installation instructions and usage instructions.

Performance requirements: specifies the performance requirements and related test methods, test evaluation criteria and test results reporting requirements necessary for a product to be in conformance with the standard. All the standards require, as the core of the performance test, a simulated 30 mph crash test in which a specified load (crash pulse) is applied to the test product. Failure to meet the evaluation criteria means that product cannot be labeled as a wheelchair transport product.

The crash test simulates a frontal crash of the vehicle, since side and rear impacts are statistically less likely to occur. Future work may address these other impact directions.

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Question 6: What is the specific scope and requirements for tiedown and restraint products in order to comply with the wheelchair tiedown and occupant restraint standards? (WTORS)-- SAE J2249 and ISO 10542

Answer:
The standards apply to:

  • both passengers and drivers (adults only-ISO),
  • both public and private vehicles
  • all wheelchairs including scooters
  • forward facing wheelchairs in the vehicle
  • crashes involving frontal impact of the vehicle only (side and rear future work).

The standards require that:

  • pelvic and shoulder restraints be used in the tests (and recommends use of both belts during transport, especially in vehicles that have occupant restraint belts normally installed)
  • a dynamic 30 mph (48kph)test be used to confirm the performance of the WTORS
  • the end fittings on tiedown straps have a specific design so that the end fitting will readily latch to the mating receptacle on the transport-tested wheelchair
  • the product be permanently labeled as to the test passed, and
  • user warnings, installation and usage instructions be provided.

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Question 7: What is the specific scope and requirements for wheelchair products in order to comply with the transport wheelchair standards? (ANSI/RERSNA-WC-19; ISO 7176-19)

Answer:
In addition to meeting most of the general requirements indicated in the question five answer, the key specific requirements that make a transport wheelchair different from regular wheelchairs may be summarized as follows:

The standards require that:

  1. the wheelchair have four clearly marked and accessible attachment points for securing the tiedown devices,
  2. each attachment point be designed to engage with the end fitting of the tiedown strap specified in the Wheelchair Tiedown and Occupant Restraint System (WTORS) standard (J2249, ISO 10542-2,
  3. the wheelchair seat structure allow the pelvic restraint (lap belt) to be snugly cross the pelvis within a specific angle range (30-75°),
  4. in the US, by April 2004, wheelchairs in compliance with WC-19 must provide a tested pelvic restraint that attaches directly to the wheelchair frame, as an available option from the manufacturer,
  5. any postural supports intended for use as occupant restraints must comply with the WTORS standards,
  6. postural supports NOT intended for use a occupant restraints must be labeled as such, and
  7. manufacturers presale literature shall contain information:
  • on the wheelchair overall size and minimum turning radius
  • a warning ‘for use only for forward facing orientation in vehicle’
  • total weight of wheelchair
  • results of the lateral movement test (WC-19 only) and a
  • description of WTORS suitable for use with the wheelchair.

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Question 8: Do the Standards apply to all mobility devices and motor vehicles?

Answer:
The standards applies to:

  • manual wheelchairs, powered wheelchairs, scooters, and tilt-in-space wheelchairs,
  • forward facing wheelchairs and occupants (adult only in ISO).
  • use in both public and privately-owned vehicles,
  • wheelchairs secured by a variety of tiedown types, i.e., strap or docking-type

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Question 9: If I have a specific disability will I be at more risk while seated in a motor vehicle?

Answer:
This is a tough one! Again, let's begin with motor vehicles and how they are safety tested by the motor industry. In most cases, standardized anthropometric test dummies (ATDs) are used in car crashes to simulate the human vehicle occupant. These ATDs are designed to represent both adults and children of different size ranges as indicated in Table I below. Excursions of the ATDS and impact forces are measured which can be equated to parameters that indicate whether the occupant would have survived the crash. The primary test simulates a 30 mph (48 kph)-20 g frontal crash condition. Other crash directions may also be tested. Motor vehicle interiors and occupant restraint systems are designed, tested and improved based on the results of the crash tests. They all assume a non-disabled, healthy individual.

Table A.1
Available ATDs for Wheelchair Testing

table A.1


If you happen to be heavier or taller then the ATD used in vehicle test, or if you are in an actual collision that generates higher impact forces then the standard crash test (say, a 60 mph head-on collision), you may very well experience higher injury producing forces and therefore be at higher risk of injury.

Transport wheelchair testing uses the same test criteria and test dummies as in motor vehicle testing. Therefore, it follows that if you are person with a disability that will not allow you to respond in a crash situation as well as person without a disability, you will most likely be at higher risk of injury. The amount of increased risk will depend on the nature and severity of your disability. It would be impossible to design and market occupant restraints and wheelchairs that would offer occupant injury protection based on the nature and extent of a person’s disability. The numbers of possible designs would be staggering and therefore not economically feasible.

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Question 10: Where can I get information about the requirements for school buses related to wheelchair transport?

Answer:
The federal regulations governing the design and construction of yellow school buses is contained in Federal Motor Vehicle Safety Standard (FMVSS) 222. FMVSS 222 is administered by the National Highway Transportation Safety Administration (NHTSA). A small section in the FMVSS-222 regs, deals with wheelchair transport in school buses.
S5.4 Each school bus having one or more locations designed for carrying a person seated in a wheelchair shall comply with S5.4.1 through S5.4.4 at each such wheelchair location.
S5.4.1 Wheelchair securement anchorages. Each wheelchair location shall have not less than four wheelchair securement anchorages complying with S5.4.1 through S5.4.1.3.
S5.4.1.1 Each wheelchair securement anchorage shall have a wheelchair securement device complying with S5.4.3 attached to it.
S5.4.1.2 The wheelchair securement anchorages at each wheelchair location shall be situated so that:
a) A wheelchair can be secured in a forward-facing position.
b) The wheelchair can be secured by wheelchair securement devices at two locations in the front and two locations in the rear.
c) The front wheel of a three-wheeled wheelchair can be secured.
S5.4.1.3 Each wheelchair securement anchorage shall be capable of withstanding a force of 13,344 Newtons applied as specified in paragraphs (a) through (d) of this section. When more than one securement device share a common anchorage, the anchorage shall be capable of withstanding a force of 13,344 Newtons multiplied by the number of securement devices sharing that anchorage.
(a) The initial application force shall be applied at an angle of not less than 30 degrees, but not more than 60 degrees, measured from the horizontal. (see figure 4)
(b) The horizontal projection of the force direction shall be within a horizontal arc of +45 degrees relative to a longitudinal line, which has its origin at the anchorage location and projects rearward for an anchorage whose wheelchair securement device is intended to secure the rear of the wheelchair. (see figure 4)
(c) The force shall be applied at the onset rate of not more than 133,440 Newtons per second.
(d) The 13,344 Newton force shall be attained in not more than 30 seconds, and shall be maintained for 10 seconds.
S5.4.2 Wheelchair securement devices. Each wheelchair securement device shall:
(a) If incorporating webbing or a strap-
(1) Comply with the requirements for Type 1 safety belt systems in S4.3, S4.3, and S4.4(a) of FMVSS No. 209, Seat Belt Assemblies; and
(2) Provide a means of adjustment to remove slack from the device.
(b) If not incorporating webbing or a strap, limit movement of the wheelchair through either the equipment design or a means of adjustment.
S5.4.3 Wheelchair occupant restraint anchorages
S5.4.3.1 Each wheelchair location shall have:
(a) Not less than one anchorage for the upper end of the upper torso restraint; and
(b) Not less than two floor anchorages for wheelchair occupant pelvic and upper torso restraints.
S5.4.3.2 Each wheelchair occupant restraint floor anchorage shall be capable of withstanding a force of 13,344 Newtons applied as specified in paragraphs (a) through (d). When more than one wheelchair occupant restraint share a common anchorage, the anchorage shall be capable of withstanding a force of 13,344 Newtons multiplied by the number of occupant restraints sharing that anchorage.
(a) The initial application force shall be applied at an angle of not less than 45 degrees, but nor more than 80 degrees, measured from the horizontal. (see Figure 5.)
(b) The horizontal projection of the force direction shall be within a horizontal arc of +45 degrees relative to a longitudinal line, which has its origin at the anchorage and projects forward. (see Figure 5.)
(c) The force shall be applied at an onset rate of not more than 133,440 Newtons per second.
(d) The 13,344 Newton force shall be attained in not more than 30 seconds, and shall be maintained for 10 seconds.
(e) When a wheelchair securement device and an occupant restraint share a common anchorage, including occupant restraint designs that attach the occupant restraint to the securement device or the wheelchair, the loads specified by S5.4.1.3 and S5.4.3.2 shall be applied simultaneously, under the conditions specified in S54.3.2 (a) and (b). (see Figure 6.)
S5.4.3.3 Each anchorage for a wheelchair occupant upper torso restraint shall be capable of withstanding a force of 6,672 Newtons applied as specified in paragraphs (a) through (d).
(a) The initial application force shall be applied at a vertical angle of not less than zero degrees, but not more than 40 degrees below a horizontal plane, which passes through the anchorage. (see Figure 7.)
(b) The projection of the force direction onto the horizontal plane shall be within zero degrees and 45 degrees as measured from a longitudinal line with its origin at the anchorage and projecting forward. (see Figure 7.)
(c) The force shall be applied at the onset rate of not more than 66,720 Newtons per second.
(d) The 6,672 Newton force shall be attained in not more than 30 seconds, and shall be maintained for 10 seconds.
S5.4.4 E Wheelchair occupant restraints
(a) Each wheelchair location shall have wheelchair occupant pelvic and upper torso restraints attached to the anchorages required by S5.4.3.
(b) Each wheelchair occupant restraint shall comply with the requirements for Type 2 safety belt systems in S4.2, S4.3, and S4.4 (b) of FMVSS No. 209, Seat Belt Assemblies.

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Question 11: What does ADA say about wheelchair transport on public transit vehicles?

Answer:
The Americans with Disabilities Act (ADA), signed into law in 1990 by the President George Bush Sr., does contain requirements specific to wheelchair access, location, and the strength of wheelchair tiedown devices. An excerpt from the ADA follows.

1192..23
(d) Securement devices. - (1) Design load. Securement systems on vehicles with GVWRs of 30,000 pounds or above, and their attachments to such vehicles, shall restrain a force in the forward longitudinal direction of up to 2,000 pounds per securement leg or clamping mechanism and a minimum of 4,000 pounds for each mobility aid. Securement systems on vehicles with GVWRs of up to 30,000 pounds, and their attachments to such vehicles, shall restrain a force in the forward longitudinal direction of up to 2,500 pounds per securement leg or clamping mechanism and a minimum of 5,000 pounds for each mobility aid.

(2) Location and size. The securement system shall be placed as near to the accessible entrance as practicable and shall have a clear floor area of 30 inches by 48 inches. Such space shall adjoin, and may overlap, an access path. Not more than 6 inches of the required clear floor space may be accommodated for footrests under another seat provided there is a minimum of 9 inches from the floor to the lowest part of the seat overhanging the space. Securement areas may have fold-down seats to accommodate other passengers when a wheelchair or mobility aid is not occupying the area, provided the seats, when folded up, do not obstruct the clear floor space required. (See Fig. 2)

(3) Mobility aids accommodated. The securement system shall secure common wheelchairs and mobility aids and shall either be automatic or easily attached by a person familiar with the system and mobility aid and having average dexterity.

(4) Orientation. In vehicles in excess of 22 feet in length, at least one securement device or system required by paragraph (a) of this section shall secure the wheelchair or mobility aid facing toward the front of the vehicle. In vehicles 22 feet in length or less, the required securement device may secure the wheelchair or mobility aid either facing toward the front of the vehicle or rearward. Additional securement devices or systems shall secure the wheelchair or mobility aid facing forward or rearward. Where the wheelchair or mobility aid is secured facing the rear of the vehicle, a padded barrier shall be provided The padded barrier shall extend from a height of 38 inches from the vehicle floor to a height of 56 inches from the vehicle floor
with a width of 18 inches, laterally centered immediately in back of the seated individual. Such barriers need not be solid provided equivalent protection is afforded.

(5) Movement. When the wheelchair or mobility aid is secured in accordance with manufacturer's instructions, the securement system shall limit the movement of an occupied wheelchair or mobility aid to no more than 2 inches in any direction under normal vehicle operating conditions.

(6) Stowage. When not being used for securement, or when the securement area can be used by standees, the securement system shall not interfere with passenger movement, shall not present any hazardous condition, shall be reasonably protected from vandalism, and shall be readily accessed when needed for use.

(7) Seat belt and shoulder harness. For each wheelchair or mobility aid securement device provided, a passenger seat belt and shoulder harness, complying with all applicable provisions of 49 CFR part 571, shall also be provided for use by wheelchair or mobility aid users. Such seat belts and shoulder harnesses shall not be used in lieu of a device which secures the wheelchair or mobility aid itself.

http://www.access-board.gov/transit/html/vguide.htm#BVSM

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Question 12: If I have a wheelchair with a tilting seat frame, what is the best way to secure the wheelchair to the vehicle?

Answer:
The short answer is that it depends on whether one is talking about a transit wheelchair or a non-transit wheelchair.

For non-transit wheelchairs that do not have designated securement points and that do not comply with WC/19, which people are going to have to continue to deal with for the foreseeable future, it is generally been recommended that both the front and rear securement points be either on the front and back of the seat or on the front and back of the base wheelchair frame, if it is possible to find four relatively strong attachment points on either. This is done to minimize the chance of extreme slack developing in the tiedown system which would occur if the seat tilt angle changes, resulting in large changes in distance between point on the wheelchair base at one end of the wheelchair and points on the wheelchair seat at the other end. In addition, it has also been recommended that it is preferable to find these four points on the seat, since these points will usually provide slightly steeper tiedown strap angles that increases wheelchair stability and reduces upward movement of the wheelchair in a crash situation.

For transit wheelchairs, however, it is not as important for all four securement points to be on the seat or on the base. This is because a transit wheelchair will have been dynamically strength tested using the securement points provided by the manufacturer, wherever they are. It is, however, still preferable for the securement points to be located high on the wheelchair base or seat frame, rather than down low near the floor (note the minimum height allowed by WC/19 is 100 mm = 4”) to increase wheelchair stability during transit and reduce upward motion and pivoting of the wheelchair in a frontal crash. However, even though manufacturers are placing securement points lower on some transit wheelchair frames than is preferred, these wheelchairs still comply with WC/19 and have therefore demonstrated effective crash performance with these locations.

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Question 13: I must use my wheelchair on the bus with the seat tilted back, does this put me at increased risk of injury?

Answer:
There are really two issues that should be considered. First, if the wheelchair has been tested to the transport standard that means that the tilt mechanism and the remainder of the seating components are likely strong enough to prevent catastrophic failure and excessive movement of the occupant within the vehicle. Secondly, if the seat and backrest tilt as one unit, versus a seat with only a backrest recline, the occupant will more likely be retained in a better position relative to the seat and the occupant restraint when both apply forces to the body during a crash event.

The standards, as such, do not place any specific requirements on the backrest recline or seat tilt angles for transport wheelchairs. The only requirement of WC/19, for example, is that the wheelchair design allows the backrest to be positioned within 35 degrees of vertical and the seat to be positioned within 30 degrees of horizontal. That is, WC/19 recognizes that wheelchair users need to attain a variety of tilted seated postures, but these should be within specified maximum limits. Therefore, stretchers, beds, and other devices that allow positioning persons in a prone posture could not comply with WC/19.

WC/19 also requires manufacturers of transit wheelchairs to provide instructions and warnings in the wheelchair literature that the wheelchair backrest should not be reclined more than 35 degrees to the vertical and that the seat of a wheelchair should not be inclined more than 30 degrees to the horizontal. These maximum ”recommended” backrest and seat angles are to optimize the performance of belt-type restraint system. For example, it is preferable if the lap is at an angle of 45 to 75 degrees relative to the horizontal but also at angle of 30 degrees or more to the occupant’s thigh angle, so that the lap belt will remain low on the pelvis in a frontal crash and minimize the possibility of the belt loading the relatively soft abdomen. The shoulder belt should be in close proximity to, and preferably in contact with, the chest and shoulder to reduce the velocity and force of shoulder and chest loading in a frontal crash. If the torso is reclined too much, the distance between the belt webbing and the occupant will tend to increase and the forces on the occupant. Also, with a more upright torso posture, the shoulder will tend to take more of the load, and thereby reduce the forces on the chest.

In some situations it may be necessary to recline the backrest or tilt the backrest and seat of a wheelchair more than these recommended limits. This may result in some reduction in the performance of the belt restraint system, but it is sometimes a tradeoff that must be made. In these situations, it is still desirable to keep the lap belt low and keep the shoulder belt as close to the torso as possible, perhaps by adjusting the locations of the belt anchor points in the vehicle.

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Question 14: What should I do if I use a very heavy wheelchair that may exceed the capacity of existing tiedown devices?

Answer:
The question of when and whether to use additional tiedown straps is up to the wheelchair user, the transit provider, etc. and depends on a number of factors. The Answer: probably also depends on whether the wheelchair complies with a transport standard, as will be explained shortly. For wheelchairs that do NOT comply with a transport standard, the more straps the better on heavy chairs. However, finding even four suitable securement points is problematic on many wheelchairs, and of course none of these points have been dynamically tested.

The need for additional straps also depends on the type of vehicle and transit mode. For large city buses and large school buses, more than four straps is probably not warranted, especially for transport-tested wheelchairs, since this type of vehicle is very unlikely to ever experience a 30 mph crash to which tiedown straps that comply with tiedown standards have been tested.

Another factor that could influence the decision about whether and when to use additional tiedowns is whether the occupant is restrained by belts that anchor to the wheelchair (i.e., wheelchair integrated restraints) or restraint belts that anchor directly to the vehicle. That is, when the occupant restraint loads are combined with the heavy wheelchair loads, the combination may exceed the capacity of only two rear tiedown straps.

In the case of WC-19, the standard allows wheelchairs that weigh more than 275 lbs. to provide for more than four securement points (e.g., 3 or 4 in the back). It also requires that the manufacturer indicate in their presale literature the number of securement points and tiedown straps that were used in the frontal impact test, if it is other than the minimum four. Note that wheelchairs that weight less than 275 lbs. must pass the test with only four securement points and that wheelchairs that weigh more than 275 lbs. don't have to use more than four securement points.

However, whether or not a wheelchair has been tested with four, or more than four tiedown straps, the decision of whether to use four or more tiedowns in the real world may be different. For example, if a 280 lb wheelchair is tested using five securement points with three of these for rear securement, a transit provider for large city buses or large school buses might decide to use only two of these rear securement points, since a large vehicle is extremely unlikely to ever experiences anything close to a 30 mph impact. Similarly, if a 200 or 250 lb. wheelchair is used in a van-sized vehicle that travels the highways, the user or transit provider might decide to use four rear tiedown straps instead of just two. This can be done because the geometry of the securement points required by the standards will allow two tiedown straps to be attached to each of the rear securement points.

In summary, the questions about whether to use more than four tiedown straps for heavier wheelchairs and for situations with wheelchair-integrated restraints, and at what wheelchair mass to implement additional tiedowns do not have simple answers. The answers depend not only on the type of vehicle and travel mode, but also on how much additional risk you are willing to trade off for the conveniences of using only four tiedown straps instead of more than four straps. If you are very conservative and don't want any additional risk, and are willing to put up with additional time and effort to secure a wheelchair, then you might decide to use four rear tiedown straps in a van-sized vehicle whenever the wheelchair mass exceeds 250 lbs. However, if you are willing to take some additional risk (maybe not protect the wheelchair occupant quite as well in 25 - 30 mph impacts, because reduced time and effort is very important, then you might not use more than two rear tiedown straps for wheelchairs that weigh as much as 250 lb in van-sized vehicle. At no time should one use less than four transport-tested tiedown straps, two in the rear and two in the front.

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Question 15: Does a transit-tested wheelchair need to be replaced if it has been involved in a crash?

Answer:
This question has been recently raised along with the implication that the fact that a transit-tested wheelchair might need to be replaced after a vehicle crash is a negative feature of transit-tested wheelchairs. First, it is important to be clear that wheelchair transport standards do not even address this question, although a future version should probably do so by a requirement in the manufacturers instructions and/or warnings to the consumer.

One simple answer to this question is that a transit-tested wheelchair is much less likely to need replacement or repair following a crash than is a non-transit wheelchair. A more specific answer is that the need to replace and/or repair a wheelchair following a crash depends both on the severity of the crash and the damage experienced by the wheelchair. In low level crashes, it is unlikely that a transit-tested wheelchair would need to be replaced or repaired. In more severe crashes, it may only be necessary to replace certain components that have been severely loaded and deformed. When in doubt about the level of damage to a wheelchair, it is best to check with the wheelchair manufacturer or supplier if the wheelchair was occupied and secured in a crash that required the vehicle to be towed from the scene. Whatever the need, it seems evident that the repair or replacement of a wheelchair that has been involved in a severe crash is a small price to pay if it performed well enough to allow the restraint system to protect the wheelchair user from serious injury.

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Question 16: Does designing a wheelchair to comply with transport standards conflict with the other features and functions of wheelchairs that are important to wheelchair users on a daily basis?

Answer:
This question is prompted by the fact that some individuals are beginning to express concern that making a transit wheelchair means sacrificing some other features of a wheelchair that may be more important to the wheelchair user on daily basis, thereby leading to a need to make a decision about trading off safety in a motor vehicle for functionality during daily living.

There is, no evidence to support such concerns or claims. Other than having four easily visible and accessible dynamically tested securement points, having less injury producing protrusions, and being more compatible with occupant restraints, wheelchairs with the transit options should be little different in design and function than non-transit wheelchairs. The features that give the wheelchair improved dynamic strength should be essentially invisible to the user, and should also improve overall wheelchair durability of the wheelchair.

Question 17: What should I do about auxiliary equipment on transit wheelchairs, such as trays, augmentative communications aids, oxygen tanks, and other add-on equipment that may be necessary for the particular wheelchair user?

Answer:
First, the transport standards do not directly address the design, performance, or securement of auxiliary or add-on equipment and devices, other than requiring batteries, motors, and other electrical components that are inherent parts of powered wheelchairs, or any other wheelchair component in excess of 100 g, to remain attached to the wheelchair during the 30-mph frontal crash test. However, the standards do address wheelchair add-on equipment indirectly by requiring the wheelchair manufacturer to provide instructions and warnings in their user manuals that alerts the consumer to:

  • Remove and secure auxiliary equipment separately in the vehicle whenever possible
  • Secure auxiliary equipment to the wheelchair so that will not break free and injury other occupants in a crash
  • Use gel cell batteries on powered wheelchairs, and
  • Use soft or padded trays for situations when they cannot be removed from the wheelchair during transit

Although users of transit wheelchairs should contact the manufacturer with regard to making any significant changes to the basic structural components of the wheelchair or seat, it should not be necessary to consult the wheelchair manufacturer for dealing with the variety of add-on equipment during transit. Rather, it is simply important to realize that this equipment, and particularly heavier and rigid items, probably need to be secured more effectively to the wheelchair than is typically done for daily use, and that it should be removed and secured elsewhere in the vehicle, if this is possible. The strength of the device or mechanism needed to secure the item will depend on the weight of the add-on component, but there are many types of tiedown and mountaineering straps that should be very suitable for most equipment. It is, of course, possible to test these retention devices by using them to secure add-on devices to the wheelchair during a 30-mph frontal impact test of the wheelchair but the standards do not yet require that this be done. Another complication is that many of the add-on devices are not provided by the original wheelchair manufacturer.

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Question 17: Are there weight limits for people who can purchase and use a transit wheelchair based the size of crash test dummies?

Answer:
General Motors or Ford does not restrict the sale of passenger vehicles to consumers who weigh less than the 170-lb crash dummy used in crash tests required by federal safety standards.

To clarify, the transport standards specify that the size and weight of the crash dummy used in the 30-mph frontal impact test be representative of the size and mass of the largest person for which the wheelchair is designed. Thus, if a wheelchair is designed only for use by children, then either the six-year old 60-lb crash dummy or the 100-lb small-adult dummy would be recommended for use in the sled impact test. However, if the wheelchair is designed for use by a wide range of adults, the test specifies that a 170-lb or 50th-percentile adult male crash dummy be used. The manufacturer can also choose to use a larger 95th percentile adult male dummy, but this heavier dummy is not required, even though the wheelchair may be designed for, and capable of, being used by persons with a body weight of 220 lbs or more.

Any standard requires that a product be tested to a set of reasonable, but somewhat worst-case, conditions that might be experienced in the real world. It is rare that a standard would require products to be tested at the absolute extreme conditions of potential real-world exposure, especially when the likelihood of that exposure is very remote, as it the case with vehicle crashes. A 170-lb crash dummy represents about a 75th percentile adult by height and weight. Similarly the 30-mph crash test represents about a 95th percentile pure frontal crash pulse for a passenger size vehicle. In the real world, people who ride in vehicles are exposed to a wide range of conditions and circumstances that can increase the risk of injury beyond that covered by safety testing. The impact severities can be greater than 30 mph and be from different directions. Older occupants are at higher risk of injury than younger occupants. Heavier occupants may be at greater risk than lighter-weight occupants. People in smaller vehicles traveling at higher speeds are at greater risk of injury in a crash than people in larger vehicles and/or vehicles traveling at slower speeds. A standard cannot and does not provide everyone with the same risk to injury in a crash.

Although the level of injury risk will vary widely depending on a wide range of occupant, vehicle, and crash variables, all wheelchair users who cannot transfer from their wheelchair when traveling in a motor vehicle, will be at reduced risk of injury if they are seated in a transit-tested wheelchair. Heavier persons can benefit from transit wheelchair just as much as people who weigh less than the crash dummy. Thus, wheelchair manufacturers should not limit the sale of transit wheelchairs to consumers who weigh the same or less than the crash dummy used in the tests. The only restriction should be on the general design capacity of the wheelchair for normal everyday use.

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Question 18: How can I help move this effort forward more quickly?

Answer:
Most manufacturers of both tiedowns/occupant restraint devices and wheelchairs have actively participated in the development of the standards as well in testing their products to the standards. This has been a significant financial investment by the manufacturers to improve the transit safety of their products. Since compliance with the standards is voluntary, there are unfortunately still products that are being marketed that are clearly intended for use in motor vehicles that have not been tested to the standards. The single most effective way to rectify this problem is for consumers, parents, caregivers and prescribers to request and whenever possible only purchase products that have been tested to one or more of the appropriate transport standards. If the product is in compliance it should be so labeled on the product.

For those interested in becoming more directly involved in the standards development process, there is way that you can be added to the email listings or working groups. The standards working groups are always open to manufacturers, researchers, consumers and clinicians who wish to contribute their experiences and participate in the debate that moves the work forward. Although several of the key standards have now come to a conclusion and have been adopted by various national and international standards organizations, all standards are reviewed at least every five years, and sooner if necessary. Secondly, new areas of standards debate have begun to address the remaining gaps from the initial development effort. For more information on how to become involved:

1) USA: contact Larry Schneider, Chair, RESNA SOWHAT, lws@umich.edu
2) International (ISO): contact Aleid Hekstra, chair WG-6, EDPC@HANDICOM.NL

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Question 19: Do you have any general information on the ANSI/RESNNA WC-19 standard that our organization could use in their monthly newsletter?

Answer:
Yes, there was a news release prepared by the RESNA SOWHAT Subcommittee announcing the passage of the WC-19 standard in April 2000. The following announcement is free for dissemination by any organization.

News Release
New Transit Wheelchair Standard-ANSI/RESNA WC-19
6/22/00
A new national wheelchair standard that addresses the design and performance of wheelchairs when used as seats in motor vehicles has recently been approved by the American National Standards Institute (ANSI). The new standard is based on the fact that the most effective and common method for securing a wide range of wheelchair types and sizes in both public and private vehicles, is a four-point, strap-type tiedown system. Thus, one of the primary requirements of the new standard is that a “transit” wheelchair (i.e., a wheelchair designed for occupancy in a motor vehicle according to WC/19) be provided with four easily accessible tiedown points for facing-forward securement in a motor vehicle. The standard further requires that the wheelchair and securement points be dynamically crash tested at 30 mph with an appropriate size crash test dummy seated in the wheelchair. The wheelchair may also be designed to be secured by other more automatic tiedown methods, but it must provide for four-point securement to comply with the new standard.

In addition to addressing the dynamic strength and crashworthiness of wheelchairs, the new standard aims at improving the ease by which a wheelchair can be secured using a four-point tiedown system, by requiring the four tiedown points be easily accessible using hook-type attachment hardware. Wheelchairs that comply with the standard will therefore not only make riding in a motor vehicle safer for the wheelchair user, but it will make it much easier quicker for those involved in securing the wheelchairs in public transit vehicles.

While the primary goal of the standard is to reduce the potential for injury to wheelchair-seated occupants in the event of a vehicle impact, the standard also addresses wheelchair performance related to normal vehicle operating conditions. For example, the size and turning radius of a wheelchair may affect the ease of entering and exiting a motor vehicle, and maneuvering inside the vehicle into a forward-facing position at a designated tide down station. Accordingly, the standard requires that information regarding a wheelchairs size and turning radius be provided in the manufacturer’s presale literature. Also, the lateral stability of a wheelchair can affect the comfort and security of the user during travel, so the standard requires measurement and disclosure of lateral movement in a wheelchair tilt test.

Of importance to the seating clinicians and users is that by April 2002, all wheelchairs in compliance with WC-19 shall provide for anchorage of a pelvic belt that meets specific location and strength requirements.

When development of the new standard began over four years ago, very few wheelchairs were designed with concern for occupancy and crashworthiness in motor vehicles. According to Dr. Schneider many wheelchair companies, and all of the larger wheelchair manufacturers, are already designing and crash testing many wheelchair models to the requirements of this new standard. He further notes that it is important to view the new standard in the totality of daily wheelchair functions and uses, and the range of other standards to which all wheelchairs should comply. Wheelchairs must first serve as effective mobility devices and transportation is only one activity that introduces additional unique circumstances and requirements that wheelchairs and wheelchair occupants will experience.

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Question 20: Where can I get a complete copy of the current industry standards?

Answer:

Canada:
Z604: Transportable Mobility Aids -(Feb., 1997)
Z605: Mobility Aid and Occupant Restraint –(Feb., 1997)
As of March 2001, both Z604 and Z605 are under revision which should help to align them more closely with the US and ISO counterparts.
Source: http://www.csa.ca/english/home/index.htm

U.S:
The ISO standards were developed with strong participation from the US, therefore the harmonization between the US the ISO efforts are much closer.
At present, the completed US and ISO standards are as follows:

SAE J2249 (WTORS): Wheelchair Tiedown and Occupant Restraint Systems-(January-1997)
SAE J2252: Mechanical Drawings for the Surrogate Test Wheelchair (January-1997)

Source: Society of Automotive Engineers, 400 Commonwealth Drive, Warrendale, PA 15096-0001. 1-877-606-7323 (U.S. and Canada only) or 724/776-4970 (outside the U.S. and Canada)
Web: http://www.sae.org/about/contact.htm

As of March 2001, both SAE J2249 and J2252 are under revision. This should increase harmonization with the more recently completed ISO counterpart. Also, the approach taken in the US was to develop one all encompassing standard for wheelchair tiedowns and occupant restraints, whereas in the ISO, the approach has been to develop interrelated parts as indicated below.

ANSI/RESNA WC-19: Wheelchairs Used as Seats in Motor Vehicles (April-2000)
Source: RESNA: 1700 North Moore Street, Suite 1540, Arlington, VA 22209-1903
Phone: 703-524-6686 Fax: 703-524-6630 TTY: 703-524-6639
email:info@resna.org http://www.resna.org

ISO:
10542-Part 1: Wheelchair Tiedown and Occupant Systems- General requirements and test methods for all systems (Spring-2001)
10542-Part 2: Wheelchair Tiedown and Occupant Systems- Four point strap-type tiedown systems (Spring-2001)
The current plans call for the ISO 10542 standard to ultimately contain five parts:
10542-Part3: Wheelchair Tiedown and Occupant Systems-Docking Systems (2003) 10542-Part4: Wheelchair Tiedown and Occupant Systems-Clamping Systems (2002)
10542-Part5: Wheelchair Tiedown and Occupant Systems-Systems for Specific Wheelchairs (2002)

ISO 7176-19 Wheelchairs: Wheelchairs for Use in Motor Vehicles (Summer, 2001)
ISO 16840 Wheelchairs seating: Seating Devices for Use in Motor Vehicles (2003)
Source: http://www.iso.ch/infoe/contact.htm

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