Interpretation ID: 2773y
7709 Wallace Street
Merrillville, IN 46410
Dear Mr. Walters:
This is in reply to your letter of October 8, l990, to Ms. Erika Jones, formerly Chief Counsel of this agency. You have asked that we review the enclosures to your letter, and provide "the reason why this system is not being used."
The primary material you enclosed is a patent granted May 1, l990, for an "Automobile Warning Light Improvement." The purpose of the "Improvement" is to enhance existing rear signal lamps by sending an advance warning of driving situations which have the potential of impeding the flow of traffic. The device activates the center highmounted stop lamp under situations other than when the brake pedal is applied. According to the patent, the device causes the center lamp to operate in a steady-burning mode when a vehicle is in reverse gear, and in a flashing mode when the turn signals are operating. When activated under these conditions, the center lamp will be deactivated when the accelerator is depressed.
The reason why this system cannot presently be used is that its installation would create a noncompliance with existing requirements. The performance of the center highmounted stop lamp is specified by Federal Motor Vehicle Safety Standard No. l08, Lamps, Reflective Devices, and Associated Equipment. Paragraph S5.5.4 of the standard specifically states that "The highmounted lamp on passenger cars shall be activated only upon application of the service brakes." In addition, the effect of paragraph S5.5.10 is to require all stop lamps to be steady burning when in use. Activation of the center lamp by means other than application of the brake pedal (such as putting the vehicle into reverse gear, or activating the turn signals), and in a mode other than steady burning (flashing with the turn signals) is prohibited by Standard No. l08.
The reason why this system is unlikely to be used in the future is that it appears to have little if any potential for improving motor vehicle safety. Backup lamps, turn signal lamps, and center stop lamps have specific and different tasks to perform. Use of the center lamp to assist the other lamps in performing their tasks has the potential for creating confusion. The red center lamp used alone sends an unmistakable message: this vehicle is braking, with a deceleration that may lead to a stop. It is a message to which the motoring public is accustomed. Use of the center lamp when the backup lamps are on sends a false signal that the vehicle may be decelerating in a forward motion or stopped when, in fact, it may be proceeding in a reverse motion. Use of a flashing stop lamp, mounted on the centerline of the car, in conjunction with a turn signal lamp that is flashing either to the right or left of the centerline, has the potential also to create confusion as to the intent of the driver, and distracts attention from the message sent by the turn signal that the vehicle is changing lanes or preparing to turn.
We appreciate your interest in safety and in bringing this invention to our attention.
Sincerely,
Paul Jackson Rice Chief Counsel
ref:l08 d:l2/3/90