Interpretation ID: nht92-4.43

DATE: August 10, 1992

FROM: Dan Trexler -- Specifications Engineer, Thomas Built Buses, Inc.

TO: Paul Jackson Rice -- Chief Counsel, NHTSA

COPYEE: Ron Holzhauser; Fred Huston; Ron Marion

TITLE: None

ATTACHMT: Attached to letter dated 10/2/92 from Paul Jackson Rice to Dan Trexler (A-40; Std. 131) and letter dated 9/14/92 from Paul Jackson Rice to Lyle Walheim (Std. 131)

TEXT:

This letter is to formally request an interpretation of certain portions of FMVSS 131, School Bus Pedestrian Safety Devices.

It has come to our attention that there is some confusion and possible misinterpretation of the stop arm's activation and the manual override device requirements and allowances contained within 131.

Upon reading the requirement for the stop arm's "manner of activation" specified in section S5.5 of 131, it seems that it is connected to just the activation of the red signal lamps of FMVSS 108. Based on this assumption our first question is: 1. On buses with just a four light system (as specified in S5.1.4(a) of FMVSS 108), is the stop arm required to extend every time the signal lamps are activated?

On the other hand, when considering an eight light system (as specified in S5.1.4(b) of FMVSS 108) the activation of the stop arm seems to be connected to not only the activation of the red signal lamps but also the prerequisite opening of the bus entrance door as specified S5.1.4(b)(ii). This leads to our second question: 2. On buses with an eight light system (as specified in S5.1.4(b) of FMVSS 108), is the stop arm required to extend only after the red signal lamps have been activated by the opening of the bus entrance door? Or is the stop arm required to extend at any time the red signal lamps are activated?

Our final area of confusion concerns the override device. Our third question is: 3. Can a device be used that is capable of remaining in the "OVERRIDE" or "ON" position with only a one-time activation by the driver?

An example of this would be a toggle or rocker switch on the dash or switch cabinet that could be moved to the "OVERRIDE" or "ON" position, by the driver, and left in that position. Various attributes of this system would include an audible signal, of course, that would automatically sound for at least 60 seconds and automatically recycle each time the service door was opened, with the engine running. Activation of the audible signal would be triggered by the activation of the red signal lamps as specified in S5.1.4 of FMVSS 108. Upon deactivation of the override switch, the stop arm would be deployed, if the signal lamps are still activated.

The key to this final question is the type of switch used for the override and if it is acceptable to use a switch that can remain in the "ON"

position as opposed to one that has to be "re-activated" each time the override is desired or a switch that has to be held manually in the "OVERRIDE" mode by the driver.

We appreciate your consideration of these problems and look forward to your response.