Interpretation ID: nht75-2.47

DATE: 08/22/75

FROM: AUTHOR UNAVAILABLE; R. L. Carter; NHTSA

TO: F. A. McNiel

TITLE: FMVSS INTERPRETATION

TEXT: On May 12, 1975, you petitioned the National Highway Traffic Safety Administration for rulemaking to amend Standard No. 108 to provide "A means that will hasten the illumination of a vehicles conventional stop warning lamps at any time that a 'panic' or any other exceptionally sudden stop is made, but wherein the said means will not affect the normal functioning of the vehicles lighting system at any other time."

We have given thoughtful consideration to your petition. It appears to us that the system you prefer would indicate only that the accelerator pedal had been released suddenly, and not that a sudden or "panic" stop was being made. In our view, a sudden release of the accelerator does not necessarily mean that a panic stop is in progress. Conversely, all sudden stops are not necessarily accompanied by a sudden release of the accelerator. In short, the presumed benefit of the system appears speculative, and no data have been submitted demonstrating that the signaling system would enhance highway safety. For these reasons your petition must be denied.

Standard No. 108 would not preclude the sale of your deceleration warning device in the aftermarket, subject to regulation by the individual States.

We appreciate your interest in motor vehicle safety.

Sincerely,

ATTACH.

Robert L. Carter Associate Administrator -- National Highway Traffic Safety Administration, Motor Vehicle Programs

Dear Mr. Carter:

The May 1, 1974 issue of 'Status Report' published by the Insurance Institute for Highway Safety contained an article stating that your agency had proposed amending Motor Vehicle Safety Standard No. 108 to allow the use of (1) a vertically mounted rear facing red-yellow-green lamp system that signals braking, no pedal application, or acceleration. -- or (2) Pulsating rear lamps that indicate when the vehicle is decelerating rapidly. - The proposal would also allow for the use of a combination of both systems.

Apparently both of these systems require auxiliary lamps in addition to the vehicles existing stop-light signal lamps. I am petitioning that Motor Vehicle Safety Standard No. 108 be further amended to include basically the following - "A means that will hasten the illumination of a vehicles conventional stop warning lamps at any time that a 'panic' or any other exceptionally sudden stop is made, but wherein the said means will not affect the normal functioning of the vehicles lighting system at any other time".

It has long been a universally recognized and accepted fact that the flash of a lead vehicles stop-lights signal a following driver that the lead vehicles momentum is being retarded, possibly to the extent of a complete stop. As everyone knows there has been no basic improvement in a vehicles stop warning system since the adoption of the brake operated stop-light switch. - You could obtain an 'add-on' stop-light kit for a Model-T more than fifty years ago that would function just as effectively as the conventional stop-light system that is now in use on all modern automobiles, - either one will illuminate a stop lamp the instant that the vehicles brakes are applied.

The warning that is produced by such conventional stop-light systems is adequate under the proceedure that is customarily used by most drivers in making a normal stop, but is woefully inadequate when a 'panic' or other unexpected sudden stop is made. The critical factor in this instance is the loss of time that occurs between the driver of a closely following vehicle seeing the flash of a lead vehicles stop-lights (at which time the lead vehicles brakes are already on), and the time that the following vehicles brakes are actually applied. This time loss is composed of two very distinct and separate parts, the first part being 'driver reaction' and the second part being 'warning lag'.

Driver reaction accounts for the time loss occuring between a driver perceiving the flash of a leading vehicles stop-lights and the complete release of the following vehicles accelerator pedal. This time interval varies in accord with a specific drivers mental alertness and physical agility. It is estimated that this time loss is at least one quarter of one second for an exceedingly alert driver, and considerably more for one that is less alert. There appears to be no discernable way by which this reaction time loss can be prevented.

Warning lag is the split second that is required for a driver to shift his (or her) foot from the accelerator pedal to the brake pedal and apply pressure to energize the brake operated stop-light switch, and illuminate the vehicles stop-lights. This time interval also varies to some extent according to the agility of a particular driver. -- Extensive tests have been conducted, using electronic detonating equipment to gauge the results. These tests have established the fact that this time loss is also approximately one quarter of one second for agile drivers. - This time loss can positively be totally eliminated.

It is an accepted fact that the majority of rear-end collisions occur when one driver in a congested flow of traffic unexpectedly jams on the vehicles brakes without prior warning, to make a 'panic' or other very sudden stop, and the driver of a closely following vehicle does not have sufficient braking time to stop before ramming the vehicle ahead. - This is particularily true of 'chain-reaction' pileups where the 'warning lag' is cumulative from car to car.

Enclosed is an outline for a hypothetical traffic situation of a type that is typical of todays congested traffic conditions. The accompanying chart that is based on the conditions as set forth by the hypothetical situation illustrates precisely the results that would be obtained by the elimination of 'warning lag'. - I am also enclosing sketches and an explanation of a particular means that I have perfected, that proves beyond the shadow of a doubt that the possibility of eliminating 'warning lag' as emphasized by chart is a reality - not a 'pipe dream'.

I was informed by the National Highway Safety Bureau more than five years ago:- "The National Highway Safety Bureau is cognizant of the fact that rear end collisions account for 10 per cent of the fatal motor vehicle accidents and 49 per cent of all motor vehicle accidents". - In line with these statistics I pose the following analysis in accordance with the submitted data.

Assume that one half of all drivers that crash into a vehicle ahead see the flash of the lead vehicles stop-lights, and are on their own vehicles brakes at the time of the crash. - If the lead vehicles were all equipped with a means for the elimination of 'warning lag', this would mean that one eight of the drivers that are involved in all motor vehicle accidents would have been applying their brakes for an additional ten feet (at 30 M.P.H.) before becoming involved in an accident that would cause damage to two cars. - If this ten feet of braking did not prevent an accident occurring, it would in every instance greatly reduce the force of impact, and the resultant damages to both of the vehicles that were involved. - Thus, if the safety feature that I am advocating was standard equipment on all motor vehicles, it would greatly reduce the damages sustained by one fourth of all motor vehicles that are involved in motor vehicle accidents of any kind! - Stupendous? - but true.

If this reduced the rear-end collision fatality toll by one tenth, it would amount to the saving of one life out of every one hundred of the current traffic fatalities. - The reduction in personal injuries resulting from such accidents would be very considerable, and the monetary saving by the public would be collosal. - Also, it should permit the Insurance Companies to make a very substantial reduction in the cost of premiums that are charged the public for motor vehicle insurance.

Any vehicle that is damaged in a traffic accident is not any more valuable after it has been repaired than it was prior to the accident occurring - consequently, all expenditures that are required for both the labor and materials used for repair or replacement of vehicles that are damaged in accidents that could have been prevented are wholly wasted. - If these really enormous outlays were available for constructive purposes, it would help to bolster our sagging national economy.

In relation to the enclosed data concerning the particular means I have perfected, sketch No. 1 shows the general assembly of switch unit. Sketch No. 2 shows the unit mounted behind the instrument panel in passenger compartment of vehicle, and sketch No. 3 shows unit mounted under hood in the engine compartment of the vehicle. - Both methods of mounting as shown have been very thoroughly tested, and each has been found to function perfectly. The accompanying specifications are drawn around sketches No. 1 and No. 2. Sketch No. 3 shows some alternations in the assembly of the unit, but functioning is identical to that of sketch No. 2.

If your engineers will thoroughly check all of the submitted data they will find it to be totally correct. - Also, careful analyzation of this data will reveal that factory installation of this type of safety equipment would cost no more than does the installation of conventional turn signals.

In view of the unquestionable reduction in damages to both the vehicles and their occupants that would accrue from the use of safety equipment such as I am advocating, I request that your organization give due consideration to amending Motor Vehicle Safety Standard No. 108 to include the use of such safety equipment for improving the performance of a motor vehicles existing stop warning lamps.

In the meantime, will you please inform me if the use of safety equipment such as is described by the enclosed data is permissible under the existing Motor Vehicle Safety Standard No. 108.

Yours very truly,

Fred A. McNiel