Interpretation ID: nht79-2.33

DATE: 12/07/79

FROM: AUTHOR UNAVAILABLE; F. Berndt; NHTSA

TO: Ward Industries, Inc.

TITLE: FMVSS INTERPRETATION

TEXT:

DEC 7 1979

Mr. E. M. Ryan Ward Industries, Inc. P.O. Box 849 Highway 65 South Conway, Arkansas 72032

Dear Mr. Ryan:

This responds to your October 8, 1979, letter asking whether your new bus design will comply with Standard No. 217, Bus Window Retention and Release. The window exit that you plan to install in the bus would slide open rather than push out and would be operated by a squeeze-type force application that is parallel to the horizontal centerline of the bus.

Standard No. 217 requires buses to be equipped with emergency exits that comply with a variety of requirements. In the case of window exits, the force application for opening them depends upon the location of the release mechanism. For example, the required force application in the high force access region, according to the standard (S5.3.2), is straight and perpendicular to the exit surface.

In applying the above requirement to your vehicle, it appears that your bus would not comply with the standard. From the pictures that you enclosed with your letter, it appears that your release mechanism falls in the high force access region. If so, the force application for opening the exit is in the incorrect direction as specified by the standard. Further, your bus would use window exits that slide open rather than push out. Although, sliding emergency exits are not prohibited by the standard, they must comply with all of the standard's requirements. Also, they must be capable of complying when the non-exit half of the window is either open or closed. The agency prefers the use of push-out emergency exits, because they are less likely to "bind up" during a side impact than sliding emergency exits.

The standard was written in its present form to provide uniformity of emergency exits in buses. A uniform exit system can help prevent confusion during accidents and facilitate emergency exit of vehicles. The vehicle that you plan to build would be unlike other buses now in operation with respect to emergency exits. The NHTSA does not think that this would be desirable or in the interest of safety.

Sincerely,

Frank Berndt Chief Counsel

October 8, 1979

Office of Chief Counsel U.S. Department of Transportation National Highway Traffic Safety Admn. 400 Seventh Street, S.W. Washington, D.C. 20590

Ref: FMVSS 217 "Bus Window Retention and Release" Paragraph S5.3 and S5.4

Dear Sir:

Ward Industries proposes to incorporate in a new bus design an emergency exit described as a horizontal sliding type. The window consists of two sliding sections, one of which opens large enough to admit unobstructed passage of an ellipsoid as required and described in Paragraph S5.4.1.

The sliding section of this window slides fore and aft and parallel to the longitudinal center line of the bus. The window is not hinged at the top and does not swing out or "push out." It appears that the suggested type of emergency exit would comply with the requirements of FMVSS 217, Paragraph S5.4.1. Will this type of action be acceptable?

The latching mechanism consists of a single latch which holds the sliding section in position. (See enclosed photos.) The release mechanism requires for release a squeeze type application to open. The force application for release is aft and parallel to the horizontal centerline of the bus. Will this type of release mechanism be acceptable?

We would appreciate very much an early reply. Thank you in advance for your consideration.

Sincerely,

E. M. Ryan, Specifications Engineering Mgr.

EMR/ws

Enclosures