Interpretation ID: nht92-7.35

DATE: April 21, 1992

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

TO: Paul Jackson Rice -- Chief Counsel, NHTSA

COPYEE: Vernon Wright; Wisconsin Specification File

TITLE: Request for Interpretation: Reference: (1.) 49 CFR Part 571.131 Section S5.5. (2.) Wisconsin Administrative Code Trans 300.64 - Stop Signal Arm

ATTACHMT: Attached to letter dated 6/17/92 from Paul J. Rice to Thomas Turner (A39; Std. 131)

TEXT:

Blue Bird Body Company is in the process of implementing changes to conform to the new stop signal arm requirements of FMVSS 131. Reference 1 requires that, "THE STOP SIGNAL ARM SHALL BE AUTOMATICALLY EXTENDED in such a manner that it complies with S5.4.1, at a minimum WHENEVER THE RED SIGNAL LAMPS required by S5.1.4 of Standard No. 108 ARE ACTIVATED (emphasis added); except that a device may be installed that prevents the automatic extension of a stop signal arm." The standard continues with requirements for this device including the requirement that an audible signal shall sound when the device is activated.

These requirements are logical and can be implemented in conjunction with the use of the eight light warning systems currently required in 46 of the 50 states; however, when these requirements are considered in terms of a four light warning system, there are certain operational issues that need to be considered. Specifically, the state of Wisconsin requires a four light warning system and a stop signal arm on school buses and has the following requirements for stop signal arms per Reference 2; "(2) Any bus manufactured after January 1, 1978, shall have the stop signal arm controlled by the service door. The stop signal arm shall not become operational until the service door opens. The stop signal arm shall be installed in such a manner that it cannot be activated unless the alternating red lamps are in operation."

To meet these requirements, Blue Bird provides a system by which the alternating red flashing lamps are activated by a driver controlled manual switch and the stop signal arm is activated by opening the service door. In order to comply with the new FMVSS 131 standard, we are adding a warning buzzer that will sound when the alternating red flashing lights are activated but the service door has not yet been opened to activate the stop signal arm. We believe that this system meets the intent of Standard No. 131 but are concerned about compliance with the wording of the standard in terms of requiring "automatic extension" of the stop signal arm. The system described above for Wisconsin provides for manual activation of both the alternating red flashing lights and the stop signal arm and is not "automatic." However, it appears to meet the intent of the standard by having the stop arm extend when the service door is opened and the alternating red flashing lights are on, and by having a warning buzzer activated whenever the arm is not extended and the lights are on.

It is our understanding that the Wisconsin requirements are necessary so that the alternating red flashing lights can be used to warn traffic of an impending stop and the stop signal arm is used to actually stop traffic. They do not

want the stop signal arm to extend automatically when the red lights are activated. For an eight light warning system, the amber lights are used to warn traffic of an impending stop and it is proper for the alternating red flashing lights and the stop signal arm to be activated simultaneously to stop traffic. Since Federal Motor Vehicle Safety Standards require as a minimum a four light warning system and allow an eight light warning system, the requirements of Standard No. 131 must be compatible with both systems.

Based on the above information and reasoning, and with the best interests of school bus safety in mind, Blue Bird requests confirmation that the warning light and stop arm system and operation, as required by Wisconsin and described above, conforms to the requirements of Standard No. 131 section S5.5. Specifically we request written confirmation that when a four light warning system is used and is activated by a driver actuated switch, it is permissible for the stop signal arm to be activated by opening of the service door, provided that an audible signal warns the driver when the alternating red flashing lights are on but the stop signal arm has not been extended.

Blue Bird is working to resolve all system design and operational issues regarding Standard No. 131 in the very near future so that changes in production can be implemented in time to meet the September 1, 1992 effective date. Your prompt consideration and response to this request is, therefore, urgently requested.