Interpretation ID: maxon_threshold7346

S. Lafferty, Manager, Engineering
Maxon
16205 Distribution Way
Cerritos, CA 90703

Dear Ms. Lafferty:

This responds to you letter in which you asked about the threshold warning requirements under Federal Motor Vehicle Safety Standard (FMVSS) No. 403, Platform lift systems for motor vehicles. You stated that there is an apparent discrepancy between the threshold warning system requirement and the associated test procedure, and asked which takes precedent. As explained below, the specified test procedure for the threshold warning system requirement is consistent with that requirement.

As part of FMVSS No. 403, the agency established a threshold warning signal requirement for platform lifts in part to minimize the risk of a lift user backing off a vehicle before a lift is properly positioned. S6.1 of FMVSS No. 403 requires an appropriate threshold warning signal to be activated when any portion of a passengers body or mobility aid occupies the platform threshold area defined in S4 of that standard, and the platform is more than 25 mm (1 inch) below the vehicle floor reference plane. A platform lift must meet this requirement when tested in accordance with S7.4 of the standard.

In your letter you stated that it is possible to design a threshold warning system that "will pass a test that is performed as described in S7.4 and not completely fulfill the requirements of S6.1.3". You described a threshold warning system designed with an optical sensor at the interior boundary of the platform threshold area. You stated that such a system would activate the warning signal only when a passenger is crossing the boundary of the threshold at the same time as the platform is lower than 25 mm from the vehicle floor. You further stated that such a system would not activate a signal if a passenger were completely within the threshold area when the platform reached the specified distance from the vehicle floor. Your letter indicated that you believe that such a system would "pass" the test procedure, but not comply fully with the requirement.

A system as you described would not comply with the requirements of S6.1.3 when tested as specified in S7.4. As stated above, S6.1 requires the appropriate warning signal to activate when tested in accordance with S7.4. S7.4.2 specifies that, with the platform lift at the vehicle floor loading position:

[P]lace one front wheel of the unloaded wheelchair test device [specified in S7.1.2] on any portion of the threshold area defined in S4. Move the platform down until the alarm is actuated. Remove the test wheelchair wheel from the threshold area to deactivate the alarm. Measure the vertical distance between the platform and the threshold area and determine whether that distance is greater than 25 mm (1 in).

Thus, S7.4.2 specifies placing the front wheel of the test device on any portion of the threshold area. As explained in 49 CFR 571.4, the use of the term "any" in connection with a range of values or set of items means generally, "the totality of the items or values, any one of which may be selected by the [agency] for testing". Accordingly, the procedure specified in S7.4.2 includes placement of the front wheel that could result in the entire test device being within the threshold area prior to the platform being lowered. This also includes placement that results in a portion of the test device being on the platform.

Given the discussion above, a system such as you described would not comply when tested under S7.4.2. As such, there is no discrepancy between the requirement of S6.1.3 and the test procedure specified in S7.4.

If you have any additional questions, please contact Mr. Chris Calamita of my staff at (202) 366-0536.

Sincerely,

Stephen P. Wood
Acting Chief Counsel

ref:403#404
d.11/3/05