Interpretation ID: aiam5427
Special Transportation Twelfth National Conference on School Transportation Central Missouri State University Warrensburg
MO 64093;
"Dear Mr. Huff: This responds to your letter to Mr. Charles Hott o this agency asking about the requirements of Federal Motor Vehicle Safety Standard (FMVSS) No. 222, School Bus Passenger Seating and Crash Protection (49 CFR 571.222), for wheelchair securement devices. I apologize for the delay in responding. You ask about the need to increase Standard 222's strength requirements for wheelchair securement devices that are part of an integrated system. In an integrated system, the occupant restraint system (lap and shoulder belts) is anchored to the wheelchair securement device. You suggest that a wheelchair securement device that is part of an integrated system should be required to withstand twice the load that is required for a securement device that is not integrated with the occupant restraint system. While we share your belief that wheelchair securement devices should be sufficiently strong, we do not believe there is a need to increase Standard 222's present requirements for securement devices that are part of an integrated system. Rather, we believe a securement device that meets the standard's present requirements is capable of withstanding the forces imposed on that device in a crash, even when the device is part of an integrated system such as the one you described. As you point out in your letter, S5.4.1.3 of Standard 222 provides for increasing the load requirement for a wheelchair securement anchorage when that anchorage is used by more than one wheelchair securement device. Moreover, S5.4.3.2(e) of the standard specifies that 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 13,344 Newtons and S5.4.3.2 13,344 Newtons shall be applied simultaneously... Stated differently, the floor anchorage used for an integrated system must withstand a load of 26,688 Newtons, which is the sum of the load specified for the wheelchair securement device and the load specified for the occupant restraint. However, Standard 222 does not require increasing the load for a wheelchair securement device that is part of an integrated system, and there is valid reason for the different approach. Under S5.4.2(a) of Standard 222, wheelchair securement devices that incorporate webbing or a strap must comply with the requirements for Type I safety belt systems specified in FMVSS No. 209, Seat Belt Assemblies. Type I systems are lap belts, and are required by S4.2(b) of FMVSS 209 to have a breaking strength of not less than '6,000 pounds or 2,720 kilograms.' The 6,000 pound (2,720 kg.) requirement is equivalent to the 26,688 Newton requirement for an anchorage used for an integrated system. Thus, Standard 222 requires wheelchair securement devices to be as strong as an anchorage that secures both the wheelchair and the occupant restraint. Requiring the wheelchair securement device to be stronger than the anchorage cannot be justified by a safety need. I hope this information is helpful. Should you have any further questions or need any additional information, please feel free to contact Walter Myers of my staff at this address or at (202) 366-2992. Sincerely, John Womack Acting Chief Counsel";