Interpretation ID: aiam0643
Director
Automotive Safety Engineering
General Motors Technical Center
Warren
MI
48090;
Dear Mr. Lundstrom: This is in reply to your letter of December 21, 1971, requestin elaboration of several statements made in the denial of General Motors' petition for reconsideration of Motor Vehicle Safety Standard No. 302 of December 2, 1971. You cite four statements in our letter to you and request that we furnish supporting material regarding them. You further request that we specifically identify all material relied on by the NHTSA in reaching the quoted 'determinations' and 'findings.'; A large amount of material has been placed in this public docket a background for the rulemaking action. All of this material has been carefully studied by the NHTSA, and together with the expertise and judgment of NHTSA personnel, 'relied on' in reaching the decisions involved in issuing Standard 302. In informal rulemaking proceedings, the decisions are based on the total weight of the agency's knowledge, not on particular items of information. For these reasons, the NHTSA does not consider it appropriate, nor required by law, to sift through the background materials and identify particular items as the 'supporting material' for statements or decisions concerning the rulemaking.; I will, however, make the following comments in elaboration of th statements you have quoted:>>>1. 'The 4-inch-per-minute burn rate was incorporated into the standard as a result of the agency's determination that it provided a flammability rate sufficiently low to provide adequate escape time from a vehicle in the event fire should occur.'; The 4-inch-per-minute rate is intended to meet three safety problem created during vehicle fires. The first is that of burns to occupants resulting from contact with the flames themselves. The second is that of noxious effects resulting from the inhalation of fumes released during combustion of the vehicle interior materials. The third is the danger of crashes caused when the driver or passengers are alarmed or panic as a result of a rapidly spreading interior fire, especially from critical concentrations of combustion by- products.; The NHTSA realizes that the danger from flame and combustion by products in a burning vehicle, and the ability of occupants to leave a vehicle, will vary from situation to situation. Any flammability level set in a standard, short of inert and incombustible materials having a zero burn rate, must represent a compromise seeking reasonable cost and adequate protection. Data compiled by NHTSA and now summarized in Docket 3-3 (Docket No. N4-3-3-26) indicate that some typical interior materials burning at more than 4 inches per minute can release critical concentrations of noxious substances, particularly hydrogen chloride. This would necessitate a fast stop and exit before a panic occurs.; 2. '. . . the Administration believes there is sufficient data on th number or degree of non-fuel fires in motor vehicles to justify the 4-inch-per- minute rate.'; Data placed in the docket discuss various studies showing a larg number of these fires are of interior origin and are not fuel fires. A study made by the Illinois Institute of Technology Research Institute (IITRI) estimated that as many as 120,000 vehicle fires occur during the course of a year which originate in the vehicle compartment. The National Fire Protection Association estimated that the total number of vehicle fires for the year 1970 was 461,000. The University of Oklahoma Research Institute, using a different means for sampling, estimated the total number of motor vehicle fires to be 800,000 annually. Other figures obtained from many sources by the Oklahoma group attribute an estimated 25 percent of vehicle fires to smoking materials. Thus, the estimated number of yearly interior vehicle fires, not related to fuel, varies from 115,000 to 200,000. The NHTSA regards even the smaller figure as a significant number of potentially injurious situations.; 3. 'The evidence available to the NHTSA does not, however, indicat that it is necessary to use flame retardant treatments that display these undesirable characteristics (aging effects) in order to comply with the standard.'; Evidence that has been placed in the docket indicates that man materials exist that can meet the requirements of Standard No. 302 without undergoing flame-proofing treatments. Test results submitted by the motor vehicle industry indicate that materials that pass the flammability requirements are presently being used in the same applications as other materials that do not pass the flammability requirements. IITRI also describes various complying vinyl and cloth materials.; 4. 'Based on the Administration's findings, such a 12-per-minute rat will not provide the necessary escape time.'; The amount of noxious substances released by certain materials used i vehicle interiors that have a 12-inch-per-minute burn rate can quickly produce panic in vehicle occupants, and inhibit the safe evacuation of the vehicle. A 12-inch-per-minute burn rate for certain materials could produce in approximately 5 seconds from 50 to 100 parts per million of hydrogen chloride, a concentration generally considered subjectively intolerable. In shortly more than 20 seconds a critical concentration that is dangerous to life would be reached. This burn rate does not provide sufficient time, in our judgment, to allow for safe exit from a moving vehicle.<<<; Sincerely, Robert L. Carter, Acting Associate Administrator, Moto Vehicle Programs;