02-15356. Motor Vehicle Safety Standards

AGENCY:

National Highway Traffic Safety Administration (NHTSA), DOT.

ACTION:

Withdrawal of advance notices of proposed rulemaking.

SUMMARY:

This notice terminates rulemaking in which the agency was considering advanced glazing regulatory requirements for passenger cars and other light vehicles to reduce the risk of ejections in crashes. The agency's research and rulemaking efforts indicate that it is more appropriate for the agency to devote its research and rulemaking efforts to projects other than ejection mitigation through advanced glazing. However, with the advent of other ejection mitigation systems, particularly side air bag curtains, the agency will continue to explore the feasibility of ejection mitigation. The focus will shift from advanced glazing to consideration of more comprehensive, performance-based test procedures. If such procedures are feasible, NHTSA will focus its efforts on establishing safety performance requirements for ejection mitigation that will allow vehicle manufacturers the discretion to choose any technology that fulfills the requirements.

FOR FURTHER INFORMATION CONTACT:

For non-legal issues: Mr. John Lee, Office of Crashworthiness Standards, NPS-11, National Highway Traffic Safety Administration, 400 Seventh Street, SW., Washington, DC 20590. Telephone [phone]. Fax: [phone].

For legal issues: Ms. Nancy Bell, Office of Chief Counsel, NCC-20, National Highway Traffic Safety Administration, 400 Seventh Street, SW., Washington, DC 20590. Telephone: [phone]. Fax: [phone].

SUPPLEMENTARY INFORMATION:

I. Background

A. Prior Agency Rulemaking Efforts

The National Highway Traffic Safety Administration (NHTSA) published two Advance Notices of Proposed Rulemaking (ANPRMs) in 1988 announcing that the agency was considering the proposal of requirements for passenger vehicles intended to reduce the risk of ejections in crashes where the side protection of the vehicle was a relevant factor. In one notice, (53 FR 31712, August 19, 1988) NHTSA considered ejection from passenger cars while in the other notice, (53 FR 31716, August 19, 1988) the agency considered ejection from light trucks. The agency reported in both notices that a significant number of fatalities and serious injuries involved the partial or complete ejection of occupants through the doors or side windows.

NHTSA suggested in both notices that new side window designs, incorporating different glazing/frames, may reduce the risk of ejections. More specifically, the agency discussed the suitability of using either trilaminate windshield-type glass or side glass with an additional inner layer of plastic to mitigate ejection (windshields are already required to contain an inner layer of plastic to mitigate ejection.) The agency also described its development of a method of anchoring these glazings to the window frame by encapsulating the plastic portion of the glazing in a frame, which could be designed to accommodate movable windows. NHTSA suggested one approach to setting a performance requirement for the glazing would require no penetration of the plastic layer of a side window when impacted at 32 km/h (20 mph) with an 18 kg (40 lb) glazing impact device. The glazing impact device was proposed to represent the combined head/shoulder effective mass that would impact the glazing.

Numerous comments were received on the 1988 ANPRMs. Major issues were raised concerning the ANPRMs, primarily that the safety benefits were not quantified. Other comments included: (1) The injury criteria were not specified for side impact, (2) the practicability of glazing designs were questioned and had never been demonstrated, (3) the cost of advanced glazing was high, and (4) no objective and repeatable test procedure was proposed. Finally, the comments questioned the effect that ejection mitigating glazing would have on overall occupant injuries and fatalities, and whether this material would actually increase injuries to belted occupants due to head injury, neck loading, and lacerations.

The National Highway Traffic Safety Administration Authorization Act of 1991 mandated that the agency initiate rulemaking on rollover protection. To fulfill this requirement, the agency published an ANPRM on January 3, 1992 (57 FR 242), soliciting information concerning rollover crashes, to assist the agency in planning a course of action on several rulemaking alternatives. Forty-two comments were received from vehicle manufacturers, safety groups, retailers of aftermarket automotive equipment, automotive consultants, and a concerned citizen. Although most of the comments addressed how to reduce rollover crashes, there were some comments on improved glazing to reduce ejections when rollovers do occur.

Subsequently, a Rulemaking Plan titled “Planning Document for Rollover Prevention and Injury Mitigation, Docket 91-68 No. 1” was published for public review on September 29, 1992, (57 FR 44721). This planning document outlined crash avoidance and crashworthiness rulemaking approaches to reduce rollover-related injuries and fatalities. This document included a section concerning ejection mitigation using advanced glazing. Public comments on the glazing program were received from three organizations: Motor Vehicle Manufacturers Association, Chrysler Corporation, and Mitsubishi Motors Corporation (DOT Docket NHTSA-1996-1683). These comments were similar to the comments on the 1988 ANPRMs. The commenters questioned design practicability, the lack of standardized testing, and the potential for additional contact injuries.

B. Agency Advanced Glazing Research

NHTSA continued its research program and, in November 1995, issued a report titled “Ejection Mitigation Using Advanced Glazings: A Status Report” (DOT Docket NHTSA-1996-1782). This report documented research, which established the problem size and potential benefits of preventing occupant ejection through the front side windows during automotive crashes. A prototype glazing system, consisting of a modified door and glazing materials, was designed and demonstrated. This glazing system was designed to use higher strength window materials to withstand the force of an occupant impact and to transfer impact forces from the glazing to the door and window frame of the vehicle.

The prototype advanced glazing system was able to successfully retain an 18 kg (40 lb) mass impacting at 24 km/h (15 mph). (Subsequent to the 1988 ANPRMs, this test configuration was determined to be representative of an occupant's effective head/shoulder mass impacting the side glazing during a side impact or rollover event). The prototype glazing system was tested using a variety of window glazing materials (bilaminates, trilaminates, and polycarbonates), to assess a wide range of performance characteristics. Additionally, this research used the FMVSS No. 201 free-motion headform (FMH) to evaluate the potential for head injury to an occupant due to glazing impact. Preliminary testing with the FMH indicated a low potential for head injury from contacts with the prototype glazing system.

A public meeting was held to present and discuss this research program. NHTSA received numerous comments from this public meeting and, based on these comments, extended the research program (DOT docket NHTSA-1996-1782). In November 1999, NHTSA issued a report titled “Ejection Mitigation Using Advanced Glazings: Status Report II” (DOT docket NHTSA-1996-1782). This report extended several aspects of the previous research. A more current door/glazing system was evaluated using a variety of glazing materials. HYGE sled tests were conducted to evaluate the potential for neck injury from the use of advanced glazing systems. Additional tests were conducted to evaluate feasibility issues of using the 18 kg (40 lb) and FMH impactor component tests. The benefit-analysis was also updated to include more recent data and to address comments received in response to the previous report.

The results indicated that all but the non-high penetration resistant trilaminates had good potential for providing adequate occupant retention. Impacts into the advanced glazings produced similar potential for head injuries as impacts using the current tempered glass side windows. However, the neck measurements from impacts into glazings were not repeatable. In some cases impacts into advanced glazings resulted in higher neck shear loads and neck moments than those into tempered glass. Impacts into standard tempered glass resulted in axial loads that were comparable to those into the advanced glazings. For each neck injury measure, the lowest neck injury measurements were obtained from the tempered glass impacts.

On July 19, 2000 (65 FR 44710), NHTSA published a request for comments on the agency's second advanced glazing status report (DOT docket NHTSA-2000-7066). NHTSA received 96 comments from auto manufacturers, suppliers, safety groups, a vehicle extraction specialist, an engineering service, and private individuals. NHTSA has carefully analyzed the information provided in the comments. The automotive manufacturers commented that advanced glazing may induce head, neck and lacerative injuries and recommended that NHTSA focus on occupant containment efforts by means of side curtain air bags. All other commenters believed that advanced glazings would enhance the overall safety performance of vehicles. The private citizens did not provide technical data, but they favored the use of advanced glazing in side and rear windows of vehicles based on their belief that up to 1,300 lives may be saved each year. The manufacturers indicated that advanced glazing benefits assume a 66% belt use rate and the benefits would dramatically decline with increased seat belt use.

II. Agency Decision

In the House of Representatives Conference Report on H.R. 4475, Department of Transportation and Related Agencies Appropriation Act, 2001, Congress noted that NHTSA had been considering the utility of advanced side glazing since 1991, and directed NHTSA to complete and issue a final report on advanced side glazing. In November 2001, NHTSA completed that directive and published a final report, “Ejection Mitigation Using Advanced Glazing.” Based on its rulemaking efforts and research documented in the report, NHTSA concludes that there is no reasonable possibility of proposing regulatory requirements for advanced glazing in the foreseeable future due to safety and cost concerns.

Two primary reasons for this conclusion are the advent of other ejection mitigation systems, such as side air curtains and the need to develop performance standards for them, and the fact that advanced side glazing in some cases appears to increase the risk of neck injury. In addition, advanced side glazing would require modifications to, or the addition of, window frames on the side of vehicles and result in smaller side windows. For vehicles with framed windows, NHTSA estimates it would cost between $48 and $79 to modify the two front side windows. However, many vehicles today are produced without framed windows. NHTSA has no cost estimates for modifying windows without frames to accept advanced glazing. In addition, NHTSA has no cost estimates for modifying rear side windows for advanced side glazing. Advanced side glazing would require modifications to the design of all vehicles currently being produced to make their windows smaller, and the costs of such a design modification would be significant.

Given these concerns, NHTSA believes it would be more appropriate to devote its research and rulemaking efforts with respect to ejection mitigation to projects other than advanced glazing. Thus, the agency will not continue to examine a potential requirement for advanced side glazing. The focus will shift from advanced glazing to the development of more comprehensive, performance-based test procedures. If such procedures prove feasible, NHTSA will focus its efforts on establishing the safety performance that must be achieved. For these reasons, NHTSA has decided to terminate rulemaking on the issue of advanced glazing.

Issued on: June 13, 2002.

Stephen R. Kratzke,

Associate Administrator for Safety Performance Standards.