Interpretation ID: nht94-6.42

DATE: April 11, 1994

FROM: David Huff -- Co. Chairperson Special Transportation, Central Missouri State University

TO: Charles Holt -- NHTSA

TITLE: Wheelchair Restraint Standards Clarification

ATTACHMT: Attachment dated 8/14/94: Letter from John Womack to David Huff (Stds. 209 & 222)

TEXT: The Twelfth National Conference on School Transportation, 1995 Standards for Special Needs Bus Body Committee is currently working on appropriate standards for wheelchair and occupant restraint systems. During our research, we have encountered a situation we feel requires clarification by your office.

Wheelchair securement anchorages as defined in FMUSS 222, $ 5.4.1.1 through $ 5.4.1.3 requires that the anchorage(s) withstand certain force. Paragraph $ 5.4.1.3 indicates 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. We agree with this requirement.

Wheelchair securement devices as indicated in paragraph $ 5.4.2, if incorporating webbing or strap, shall comply with the requirements of type 1 safety belt systems in $ 4.2, $ 4.3 and $ 4.4(a) of FMUSS 209, Seat Belt Assemblies.

Many of the wheelchair and occupant restraint systems use an Integrated occupant restraint system which is anchored in series with the wheelchair securement device, such that, the lap belt anchors to the wheelchair securement near the wheelchair seat.

Our concern is that the webbing or strap for the wheelchair securement device in the integrated system has not been addressed in the amendments to FMUSS 222. It is our feeling that the wheelchair securement device webbing or strap on the integrated system should be required to withstand twice the normal load indicated in FMUSS 289, since this webbing or strap is actually securing both the rear of the wheelchair and the occupant simultaneously.

Several manufacturer's adjustment hardware is designed in such a manner that the webbing or strap is doubled in order to remove slack from the securement device. However, there are others who use only a single webbing for this purpose.

Please advice us of your understanding or interpretation of the load requirements for the webbing or strap used in the integrated systems. This information is needed as soon as possible so we may continue drafting our proposed standards.

Thank you for your assistance.