Interpretation ID: nht89-2.55

TYPE: INTERPRETATION-NHTSA

DATE: 08/03/89 EST

FROM: STEPHEN P. WOOD -- NHTSA ACTING CHIEF COUNSEL

TO: L. T. MITCHELL, -- THOMAS BUILT BUSES, INC.

ATTACHMT: LETTER DATED 02/24/89 FROM DAN TREXLER -- THOMAS BUILT BUSES INC; TO JOAN TILGHMAN -- NHTSA; OCC ILLEGIBLE; LETTER DATED 04/27/88 FORM L. T. MITCHELL -- THOMAS BUILT BUSES INC; TO ERIKA Z. JONES -- NHTSA; LETTER DATED 12/20/84 FROM FRANK BERNDT -- NHTSA TO MELVIN SMITH -- ILLINOIS DOT

TEXT: Dear Mr. Mitchell:

This responds to your letter asking us to reassess our previous interpretations of Standard No. 217, Bus Window Retention and Release (49 CFR @571.217). Before turning to the substance of your letter, I would like to apologize for the regrettable delay in this response.

You asked us to reassess a December 20, 1984 letter to Mr. Melvin Smith regarding school buses. Mr. Smith had, among other things, asked for an interpretation of the concluding sentence of S5.4.2.1(b) of Standard No. 217. Section S5.4.2.1(b) requires si de emergency doors installed in a school bus with a gross vehicle weight rating of more than 10,000 pounds to have an opening that is at least 45 inches high and 24 inches wide when the side door is extended. The final sentence of S5.4.2.1(b) reads: "A v ertical transverse plane tangent to the rear-most point of a seat back shall pass through the forward edge of a side emergency door." Mr. Smith had asked how much, if any, forward and/or rearward variation from perfect coincidence of the plane and door e dge were permissible. We responded that no variation from the explicit requirements of the standard is permissible.

Your letter stated that a requirement for an exact coincidence of the plane and door edge "opens the door to impossible manufacturing requirements," and is "an extremely difficult goal to meet." You stated that requiring an exact relationship between a p art of the seat and the door will require multiple seat installation adjustments, bending the seat, or deforming the seat padding. To avoid such burdens, you asked if the agency would consider setting tolerances for the coincidence of the points express ed in this provision. You proposed the following interpretation of the requirement for coincidence of the plane and door edge:

1. A seat back may not intrude backward into the door opening through the transverse plane coincident with the leading edge of the door opening.

2. A seat back may be located ahead of this transverse plane by no more than three-quarters of an inch, plus or minus three-quarters of an inch, or within but no more than, one and one-half inches ahead of the transverse plane coincident with the lea ding edge of the door opening.

It would be helpful to set forth some background information to fully explain why NHTSA cannot issue an intrepretation along the lines you have suggested. Section 103 of the National Traffic and Motor Vehicle Safety Act (15 U.S.C. 1392; the Safety Act) s pecifies that NHTSA shall establish by order appropriate safety standards and that the Administrative Procedure Act shall apply to all orders establishing, amending, or revoking a safety standard. The Administrative Procedure Act generally requires agen cies to publish a notice setting forth the proposed change to a safety standard, and allow the public to comment thereon, before the agency can adopt any change to the established safety standard.

Please note that the Safety Act requires public notice and comment only when adopting orders that establish, amend, or revoke a safety standard. Interpretations are not subject to the requirements for public notice and comment, because interpretations do not add, delete, or change any requirements established in a safety standard. Instead, intepretations explain how the requirements established in safety standards or the Safety Act apply to particular vehicles or equipment, or otherwise clarify the mea ning of the established requirements.

In this case, the meaning of the requirements in Standard No. 217 that "a vertical transverse plane tangent to the rear-most point of a seat back shall pass through the forward edge of a side emergency door" is clear. This language clearly and unequivoc ally requires an exact coincidence of the location of the seat back and the forward edge of a side emergency door. There is no way that we can interpret this language in accordance with your suggestion; i.e., that the seat back shall be located no more than 1 and 1/2 inches forward of the forward edge of the emergency door.

Your letter suggested a change to the requirements of Standard No. 217, not a clarification of those requirements. As explained above, the only way by which we can change those requirements is to initiate rulemaking and give the public notice of and the opportunity to comment on the proposed change. Hence, your letter asking for an intepretation would have been more properly filed as a petition for rulemaking, pursuant to the provisions of 49 CFR Part 552.

Ordinarily, we would simply notify you of your right to file such a petition and take no further action unless and until you decided to file such a petition. In this case, however, the delay in this response may have conveyed the erroneous impression th at NHTSA would provide a substantive response to your request in this interpretation. To ensure that your request receives a response addressing its merits, we will treat your letter as a petition for rulemaking filed under Part 552. We

will notify you of our response to the petition as soon as we have completed our review of it.

Sincerely,