Interpretation ID: nht93-5.9

TYPE: Interpretation-NHTSA

DATE: July 7, 1993

FROM: John Womack -- Acting Chief Counsel, NHTSA

TO: Thomas D. Turner -- Manager, Engineering Services, Blue Bird Body Company

TITLE: None

ATTACHMT: Attached to letter dated 5/17/93 from Thomas D. Turner to John Womack (OCC-8680)

TEXT:

This responds to your letter of May 17, 1993, regarding a final rule published November 2, 1992 (57 FR 49413) amending Standard No. 217, Bus Emergency Exits and Window Retention and Release. Both questions relate to S5.5.3(c) of Standard No. 217, which was added by the final rule to read as follows:

Each opening for a required emergency exit shall be outlined around its outside perimeter with a minimum 3 centimeters wide retroreflective tape, either red, white or yellow in color that when tested under the conditions specified in S6.1 of 571.131, meets the criteria specified in Table 1.

Your two questions and the answer to each follows.

1. The March 15, 1991 NPRM of Docket No. 88-21; Notice No. 2 proposed the use of "one inch wide" retro-reflective tape and item 10 of the Supplementary Information section of the final rule discussed the final rule requirement of a "minimum 1 inch wide strip of retro-reflective tape." The conversion to metric units in the final wording resulted in requirement for a "minimum 3 centimeters wide retro-reflective tape." Since the logic and rationale for the requirement is based on the use of one inch wide tape and because retro-reflective tape is currently not commercially available in metric widths, Blue Bird requests an interpretation or a change in the rule to require the tape be 1 inch or 2.5 centimeters wide rather than 3 centimeters wide.

Based on your description, the conversion of 1 inch in S5.5.3 (c) to 3 centimeters (cm) resulted in a .46 cm increase in the minimum size retroreflective tape which must be used. You also note that 3 cm retroreflective tape is not commercially available.

You are correct that there is a discrepancy between the NPRM and the final rule about the size of the tape. Pursuant to Executive Order 12770 (56 FR 35801; July 29, 1991), the agency converted U.S. units of weights and measurements to "metric equivalents" in the November 2, 1992 final rule (57 FR 49413, 49422). The term "metric equivalents" was used by the agency because the metric conversion was not intended to result in a substantive change of the final requirements. The .46 cm increase in the tape size was thus inadvertent. In light of the issues raised by your letter, we plan to issue a correction notice of the November 2, 1992 rule that would specify a minimum size of 2.5 cm for the tape. Until the correction is issued, we will not take enforcement measures regarding tape size against a manufacturer who uses 1 inch wide retroreflective tape.

2. Blue Bird is in the process of developing exit marking designs to conform to the requirement that "each opening for a required emergency exit shall be outlined around its outside perimeter....." The retro-reflective tape commercially available for this application is stiff and will not conform to rivet heads, curved surfaces, and other discontinuities. It must be located to avoid rivets, rubrails, hinges or curved surfaces and/or must have relief holes punched in it to allow installation over rivet heads. Attached are photographs of various emergency exits with tape installed around their perimeters. The photographs are labeled to illustrate the problem areas encountered and the discontinuities required to install the tape. Blue Bird requests interpretations that the tape outlining the perimeter of the exit shall be installed such that the edge of the tape closest to the emergency exit opening is not greater than 6 inches from the edge of the opening and that splits, interruptions, discontinuities and holes in the tape are allowed to avoid and/or accommodate rivets, rubrails, hinges, handle, curved surfaces, and other function components located around the exit opening.

In a June 22, 1993 phone conversation with Mary Versailles of my staff, you explained that applying the retroreflective tape over rivets, rubrails, hinges, and other irregular surfaces would result in raised areas of the tape. You believe these raised areas would allow dirt and moisture to get under the tape, and eventually result in the lifting of all or most of the tape. You also explained that you believed it was preferable to place the retroreflective tape adjacent to rivets (as is seen in the photographs you enclosed of the roof exit viewed from the front of the bus), rather than punching holes in the tape to accommodate the rivets (as in the pictures of the rear push out window or rear door), for two reasons. First, you explained that the tape is placed on the bus as one of the last steps in manufacturing a bus. If the tape must be placed over rivets, holes must be punched in the tape and the tape positioned over the rivets, which results in a very labor intensive process. Second, you explained that the edges of the tape are sealed to prevent raveling. Since holes punched into the tape for the rivets are not sealed, these holes make it easier for the tape to wear and peel off.

NHTSA interprets S5.5.3(c) to allow interruptions in the tape necessary to avoid and/or accommodate curved surfaces and functional components, such as rivets, rubrails, hinges and handles, provided, however, that the following requisites are met. In the November 2, 1992 final rule, NHTSA indicated that the purpose of the retroreflective tape would be to identify the location of emergency exits to rescuers and increase the on-the-road conspicuity of the bus. Accordingly, the retroreflective tape may have interruptions if they satisfy both of these purposes. The occasional breaks in the tape you described would not appear to negatively affect a rescuer's ability to locate the exits, or reduce the conspicuity of the bus. However, the tape should be applied as near as possible to the exit perimeter. While we do not anticipate the nearest possible location for the tape to be further than your suggested distance of six inches from the exit, it seems that for most exits, the nearest possible location would be far less than six inches. When rivets are present, NHTSA will defer to a manufacturer's decision to apply the retroreflective tape immediately adjacent to the rivets, rather than over the rivets, if the manufacturer decides that this will increase the durability of the tape.

I hope you find this information helpful. If you have any other questions, please contact Mary Versailles at this address or by phone at (202) 366-2992.