Mr. Jack Z. Zhang
P.O. Box 10-A
San Carlos CA 94070-0316

Dear Mr. Zhang:

This responds to your letter of March 24, 1997, asking the agency to support your "courtesy light." You have stated five "needs" that you ask us to address. We shall be happy to do so.

1. Whether "it is legal to install the Courtesy Signal Light (the "Light") in motor vehicles in the U.S."

As you have described it, the Light is a green-flashing signal lamp installed in the front of a motor vehicle, on its vertical centerline. Further, "[i]t starts to flash when the driver of a car pushes a switch button and it stops flashing when the driver releases the switch button."

Your letter indicates that you are familiar with the prohibition in Motor Vehicle Safety Standard No. 108 against original equipment that impairs required lighting equipment, as you have addressed this issue at length in your letter. In your view, the green color of the Light, its status as the only center-mounted front lamp, and its flash rate are such that the effectiveness of the other front lighting equipment won't be impaired. You cite other factors, such as ease of operation which we do not consider are relevant to the impairment issue.

It is imperative for safety that the messages sent by lighting equipment required by Standard No. 108, whether signaling or marking, be clearly understood at the moment other drivers perceive them. Use of a flashing green lamp on the front of a vehicle has the potential to cause confusion for the very reason that it is unique. For example, in your Figure 5 you present the hypothetical situation of a driver signaling a left turn to a vehicle approaching on the other side of an intersection who is not sure to go or stop; at this point, the first driver can flash the courtesy signal to indicate that the first driver will yield, so that the second driver "will cross the intersection with more confidence." On the contrary, we believe that the second driver may well hesitate in confusion when confronting an unfamiliar vehicle. In a real life situation, the second driver has the right of way over a vehicle approaching from the opposite direction that is signaling a left turn. Thus, the second driver should need no further assurance to proceed through the intersection. In summary, we believe that an amber flashing turn signal's effectiveness could be impaired by a front-mounted flashing green light installed as original equipment.

For the same reason, we believe that the Courtesy Signal could not be offered as an aftermarket device. The test for aftermarket devices is whether their installation by a manufacturer, distributor, dealer, or motor vehicle repair business would "make inoperative" a safety device such as turn signals. Failure to immediately perceive the intent of a turn signal would make its signal at least partially inoperative within the meaning of the prohibition.

The prohibition does not extend to the owner of the vehicle. Assuming that an owner has the capability of installing the Courtesy Signal, the question is whether the lamp is legal under the laws of the various states. We are unable to advise you of state laws and suggest that you contact the Department of Motor Vehicles of the states for their opinion.

We also raise the question of the possible effect upon safety of a lamp that requires the driver's continuing attention to activate and deactivate. This mode of signal operation has the potential to distract the driver from critical driving tasks such as braking.

2. Whether you may "petition [NHTSA] to amend Standard 108 to permit the Light as an optional lighting device for motor vehicles."

You have the right to petition for rulemaking for an amendment of this nature, but you should be aware that the agency invariably denies petitions that involves optional vehicle signaling equipment because of the importance it places on standardization of signals. Denials of rulemaking must be published in the Federal Register where they become public information.

3. Whether to submit the Light idea as a candidate for NHTSA research and development project."

Your letter states that the Courtesy Signal Light would likely reduce "Right-of-Way" and "Improper Overtaking" accidents by 50%. We have already addressed our reservations on the ability of the lamp to prevent right of way collisions. We also have reservations about its ability to prevent improper overtaking, or lane-change collisions under the conditions shown in your Figures 2 and 3. You surmise that when a vehicle wishes to enter an adjacent lane and flashes its turn signal, the driver of a vehicle in the adjacent lane can flash the Light to indicate that it is all right for the vehicle to enter the lane. The only way that the lane-changing driver is going to be able to see the Light is in a rear view mirror. The sight of a flashing green light can create a momentary distraction which could result in a rear end collision by the lane-changing vehicle with a vehicle farther ahead in the lane into which the turning vehicle is entering. The Light may also be subject to abuse, used for false signals.

I'm afraid I must say that we see very little safety benefit to this device, and do not view it as a candidate for NHTSA research.

4. Whether you may have a letter from NHTSA supporting your effort to improve traffic safety through the "Courtesy Signal Light."

We very much appreciate the fact that you have devoted time and effort to improve traffic safety. We would be interested in discussing your safety ideas further at such time as you have actual data from field trials, etc., that can support your assertions that the Light will reduce vehicular crashes and resulting deaths and injuries.

5. Whether you may present the Light and a prototype to NHTSA.

At the present time, I don't see the value of such an idea. We believe that it is an unproven concept with a possible negative impact upon safety. As I indicated above, at such time as you have actual data demonstrating that the invention will enhance traffic safety, we will be pleased to talk with you further.

I regret that we are unable to share your enthusiasm about the potential of the Light. If you have further questions about this letter, you may refer them to Taylor Vinson of this Office (202-366-5263).


John Womack

Acting Chief Counsel