Federal Motor Vehicle Safety Standards: Glazing Materials

AGENCY:

National Highway Traffic Safety Administration (NHTSA), Department of Transportation.

ACTION:

Request for comments.

SUMMARY:

This document is intended to inform the public about NHTSA's research findings to date on advanced glazing materials that may prevent ejection of vehicle occupants through motor vehicle windows during crashes. The agency has published a report titled “Ejection Mitigation Using Advanced Glazing: Status Report II.” The agency invites the public to comment on the report and share information and views with the agency.

DATES:

Comments must be received by November 16, 2000.

ADDRESSES:

Comments should refer to the docket and notice number, and be submitted to: Docket Management, Room PL-401, 400 Seventh Street, SW., Washington, DC. 20590 (Docket hours are from 10:00 a.m. to 5:00 p.m. Monday through Friday).

FOR FURTHER INFORMATION CONTACT:

The following persons at the National Highway Traffic Safety Administration, 400 Seventh Street, SW., Washington, DC. 20590:

For non-legal issues: Mr. John Lee, Office of Crashworthiness Standards, NPS-11, telephone (202) 366-2264, facsimile (202) 493-2739, electronic mail “jlee@nhtsa.dot.gov”

For legal issues: Mr. Stephen P. Wood, Office of the Chief Counsel, telephone (202) 366-2992, facsimile (202) 366-3820, electronic mail “swood@nhtsa.dot.gov”

SUPPLEMENTARY INFORMATION:

I. Background

In response to the National Highway Traffic Safety Administration (NHTSA) Authorization Act of 1991 and ongoing research into the overall issues of rollover and ejection mitigation, NHTSA initiated a specific research program concerning occupant protection in motor vehicle rollover crashes. NHTSA is addressing this occupant protection issue from two perspectives: (1) Preventing a rollover from occurring; and (2) protecting vehicle occupants if a rollover occurs, including reducing the likelihood of ejections. Almost 60 percent of rollover fatalities occur in the 10 percent of rollovers involving either complete or partial ejection of vehicle occupants. Occupant ejections occur either through structural failures, such as door openings, or through window openings. NHTSA is evaluating the potential of improved door latches, side head air bags, and advanced glazing systems to reduce occupant ejection.

These activities are detailed in the report “Ejection Mitigation Using Advanced Glazing: Status Report II.” This report has been placed in docket NHTSA-1996-1782.

This report evaluates the progress of research since NHTSA issued its November 1995 report on occupant protection research to mitigate ejection through window openings. Each year, on average, about 7,300 people are killed and 7,800 people are seriously injured because of partial or complete ejection through glazing openings such as windows and moon roofs. Of the fatalities, more than 4,400 are associated with vehicle rollovers. The majority of these rollover victims were not using seat belts. In fact, 98 percent of occupants completely ejected and killed during rollover crashes were unbelted.

It is estimated that advanced glazing systems could save between 500 and 1,300 lives per year. This estimate assumes a national seat belt use rate of about 66 percent (the yearly average and effectiveness percentages are based on data from 1992-1996 National Automotive Sampling System (NASS) Crashworthiness Data System (CDS)) and a 20 to 51 percent range of effectiveness for advanced glazing systems in preventing ejection. Higher seat belt use rates directly reduce the estimated benefits of advanced glazing systems. For example, a 71 percent seat belt use rate would reduce likely glazing benefits by 11 percent. An 81 percent use rate would reduce glazing benefits by 34 percent. As of the end of 1999, the U.S. national average seat belt use rate was 67 percent.

In NHTSA's research program, four types of advanced glazing systems were evaluated: a high-penetration resistant (HPR) trilaminate (glass-plastic-glass), a non-HPR trilaminate (a thinner glass-plastic-glass sandwich than the HPR window), a bilaminate (glass-plastic), and a polycarbonate (rigid plastic). Pilkington/Libbey-Owens-Ford assisted the agency in manufacturing prototype window systems for a General Motors C/K pickup side door. The original equipment window encapsulation (rigid plastic around the outer edge of the side window) was modified and replaced with advanced glazing design systems. Modifications were also made to the front door window frames to better retain the window during impact, while maintaining the window's ability to be raised and lowered. To date, this research has not evaluated the practicability or suitability of the proposed glazing systems in actual production vehicles. One known problem with the proposed designs is that they do not work on vehicles with frameless side windows. The proposed door modifications would either require significant redesign or not be suitable for these vehicles. Even for framed windows, some additional work (laceration, entrapment, test speeds, etc.) is needed to further examine the appropriate depth of the proposed designs. Although facial lacerations injuries are relative minor (AIS 1 or 2), they are very common and can be disfiguring. The agency plans to assess whether advanced glazings are more likely to cause lacerations than current glass. In regards to entrapment, analysis on the extracting of trapped occupants in vehicles with advanced glazing needs to be conducted. The agency plans to evaluate the ability of emergency rescue squad tools to cut through advanced glazing. In regards to test speeds, the advanced glazing systems were evaluated for their occupant retention potential at speeds of 24 kmph (15 mph). Additional tests and benefit analyses will be conducted at lower impact speeds.

The previous status report (“Ejection Mitigation Using Advanced Glazing A Status Report,” November 1995. Docket NHTSA 1996-1782 had estimated incremental production costs of $48 per vehicle for front side windows if trilaminate glazing were used and $79 per vehicle for front side windows if rigid plastic were used. The projected lead-time estimated in the previous status report was about 3 years. The cost, weight, and lead-time estimates are only applicable to vehicles with framed windows. The designs tested in this report should have incremental costs similar to the previous estimates.

Three series of tests were performed on the advanced side glazing systems. First, NHTSA used an 18 kg (40 lb.) impactor (simulating upper body/head impacts) to evaluate potential occupant retention capabilities. Second, the agency used the free motion headform (FMH)(a 4.5 kg (10 lb) device) specified for testing to the requirements of Federal Motor Vehicle Safety Standard No. 201 “Occupant Protection in Interior Impact” to evaluate the glazing systems' potential for causing head injuries. Third, the agency conducted sled tests with a full-sized 50th percentile adult male Side Impact Dummy (SID)/Hybrid III dummy to further evaluate the glazing systems' potential for causing head injuries and to evaluate neck injuries. Since ejection mitigation glazings will generally allow for greater contact time between the head and glazing than conventional side windows, the agency was concerned that there may be an increased risk of serious, head and neck injuries from contact with these new systems.

The results indicated that all but the non-HPR trilaminate had good potential for providing adequate occupant retention. Impact with the advanced glazings with the FMH produced similar potential for head injuries as impacts with tempered glass in the current side windows. In the sled tests, the neck injury measurements from dummy impacts into glazings were not repeatable, especially for impacts into current production tempered side glass. Despite this wide variability of test results, impacts with tempered glass resulted in lower neck shear loads and moments than those with advanced glazings. In each case, tempered glass impacts produced the lowest neck injury measurements.

Advanced glazing systems may yield significant safety benefits by reducing partial and complete ejections through side windows, particularly in rollover crashes. However, to ascertain the efficacy and safety of advanced glazing systems more fully, more research will be conducted into both the practicability of the prototype systems and the risk of negative, unintended consequences. Research needed to make a regulatory decision will be completed by the end of 2000. This additional research will include evaluation of the repeatability of the test procedures, refinement of the test procedures, evaluation of the likelihood of increased injuries due to partially opened windows, evaluation of impact speed, evaluation of the necessary door modifications, and development of performance criteria.

Future and ongoing research, beyond the regulatory decision point, will include full vehicle testing conducted for both rollover and side impact crash scenarios. Evaluations will be conducted on the likelihood of increased injuries to belted occupants, the potential reduction in driving visibility due to thicker window frames and smaller windows, the potential for entrapment due to more rigid side windows.

Standard test for laceration, window clarity and glass durability will be redone. As stated earlier, lacerations injuries are relative minor. Lacerations tests will be performed on available technology. The advanced glazing must still be clear for driving visibility. They will need to meet the light stability and luminous transmittance requirements of FMVSS 205 for driver visibility. Durability will still be required as with glass. The fleet field test results from the cooperative research agreement with PPG on daily wear of advanced glazing in GSA vehicles will be analyzed.

Additionally, advanced glazing systems will be evaluated against other ejection prevention and mitigation strategies. These alternate ejection countermeasures, such as the recently introduced inflatable head protection systems, will also be evaluated at the same time in making a regulatory decision. General Motors has said that side head air bags will be standard equipment on all its vehicles by 2003. Ford Motor Company will make side head air bags available in some of its 2001 sport utility vehicles.

In a highway special investigation “Bus Crashworthiness Issues” from the National Transportation Safety Board in September 1999, NHTSA has received a safety recommendation to expand its research on current advanced glazing to include its applicability to motorcoach occupant ejection prevention, and revise window glazing requirements for newly manufactured motorcoaches based on the results of this research.

For several years, NHTSA has conducted research on ejection mitigating glazing systems for use in light passenger vehicle side windows. Many of the advanced glazing systems and test procedures identified and developed in this research are probably applicable to motorcoach passenger side windows. However, because the crash environment that produces ejections in motorcoaches may be different from that for light passenger vehicles, some specific aspects of the test procedures may need to be modified.

The agency has expanded its research plan on advanced glazing to include motorcoach passenger side windows. The first task in this new research is to identify the crash environment that produces occupant ejections in motorcoach crashes, and based on that, analytically determine the occupant-to-glazing impact conditions. Other important first steps in this research are to identify the types of glazing systems currently used in motorcoaches, and to determine if some of these have ejection mitigating capabilities. The agency will seek cooperation from outside sources in obtaining the glazing systems required for this research. These systems will be evaluated for their ability to mitigate ejections, while limiting increases to head, neck, and laceration injuries. Practicability and cost issues will also be examined. We expect to begin our evaluation of the glazing systems and test procedures in the fall of 2000.

II. Questions for the Public

To assist the agency in acquiring the information it needs, NHTSA is including a list of questions and requests for data in this notice. For easy reference, the questions are numbered consecutively. NHTSA encourages commenters to provide specific responses for each question for which they have information or views. In order, to facilitate tabulation of the written comments in sequence, please identify the number of each question to which you are responding.

NHTSA requests that the rationale for positions taken by commenters be very specific, including analysis of safety consequences. NHTSA encourages commenters to provide scientific analysis and data relating to materials, designs, testing, manufacturing and field experience.

The following is a list of questions for which the agency would like to have answers. However, it does not purport to be an all-inclusive list of subjects relevant to this research. NHTSA encourages commenters to provide any other data, analysis, argument or views they believe are relevant.

1. Is the technology available for encapsulating windows in vehicles with frameless windows and for convertibles? Is it cost effective?

2. How much crash damage could be done to the new encapsulated window frame and modified door frame designs and still have them be effective in preventing occupant ejection?

3. Are there any known disadvantages of encapsulation and modified door frame design in vehicles with inflatable side impact air bags?

4. Are there any known safety disadvantages of the encapsulation glazing and modified door frame design, such as entrapment?

5. Is any work being done on human facial laceration measurement? If so, please describe that work and its results to date.

6. Are the neck injury criteria discussed in this report sufficient? Can you recommend others? Do you have test data? If so, please provide them.

7. Are the side head injury criteria discussed in this report sufficient? Can you recommend others? Do you have test data? If so please provide them.

8. Do you have any information that addresses the repeatability of glazing impact tests? If so, please provide it.

9. NHTSA used 24 kmph test speeds, simulating rollover. Are the glazing impact test speeds used by NHTSA in its testing adequate? If not why? What test speed is recommended and why?

10. Please provide any comments and supporting material on the cost, weight increase, and lead-time to manufacture advanced glazing systems.

11. Are side head airbags an alternative solution for reducing occupant ejection out of windows?

12. Would side head air bags provide any benefits that would not be provided by advanced glazing?

13. What benefits would advanced glazings offer that would not be derived from side head air bags?

14. Beyond glazing and air bags are there other alternatives that might also be effective in reducing window ejections?

15. Should the agency be working on both the advanced glazing and inflatable head restraint systems as viable, complementary technologies to solve the window ejection problem?

16. Would the test procedures being considered for evaluating the retention capability of side glazings, as described in the report, also be suitable for evaluating this capability for inflatable retention devices?

17. Based on the outcome of this research project, should the research show that the prevent of ejection can be mitigated without substantially increasing the potential for injury, should the agency require advanced glazing for passenger windows on motorcoaches and passenger windows on all types of buses categories?

III. Submission of Written Comments

How Do I Prepare and Submit Comments?

Your comments must be written and in English. To ensure that your comments are correctly filed in the Docket, please include the docket number of this document in your comments.

Your comments must not be more than 15 pages long (49 CFR 553.21). We established this limit to encourage the preparation of comments in a concise fashion. However, you may attach necessary additional documents to your comments. There is no limit on the length of the attachments.

Please submit two copies of your comments, including the attachments, to Docket Management at the address given above under ADDRESSES.

In addition, for those comments of 4 or more pages in length, we request that you send 2 additional copies, as well as one copy on computer disc, to: Mr. John Lee, Light Duty Vehicle Division, NPS-11, National Highway Traffic Safety Administration, 400 Seventh Street, SW, Washington, DC 20590.

We emphasize that this is not a requirement. However, we ask that you do this to aid us in expediting our review of all comments. The copy on computer disc may be in any format, although we would prefer that it be in WordPerfect 8.

Comments may also be submitted to the docket electronically by logging onto the Dockets Management System website at http://dms.dot.gov. Click on “Help & Information” or “Help/Info” to obtain instructions for filing the document electronically.

How Can I be Sure That my Comments Were Received?

If you wish Docket Management to notify you upon its receipt of your comments, enclose a self-addressed, stamped postcard in the envelope containing your comments. Upon receiving your comments, Docket Management will return the postcard by mail.

How Do I Submit Confidential Business Information?

If you wish to submit any information under a claim of confidentiality, you should submit three copies of your complete submission, including the information you claim to be confidential business information, to the Chief Counsel, NHTSA, at the address given above under FOR FURTHER INFORMATION CONTACT. In addition, you should submit two copies, from which you have deleted the claimed confidential business information, to Docket Management at the address given above under ADDRESSES. When you send a comment containing information claimed to be confidential business information, you should include a cover letter setting forth the information specified in our confidential business information regulation (49 CFR part 512.)

Will the Agency Consider Late Comments?

We will consider all comments that Docket Management receives before the close of business on the comment closing date indicated above under DATES. To the extent possible, we will also consider comments that Docket Management receives after that date. If Docket Management receives a comment too late for us to consider in developing a proposal (assuming that one is issued), we will consider that comment on that proposal.

How Can I Read the Comments Submitted by Other People?

You may read the comments received by Docket Management at the address given above under ADDRESSES. The hours of the Docket are indicated above in the same location.

You may also review the comments on the Internet. To access the comments on the Internet, take the following steps:

(1) Go to the Docket Management System (DMS) Web page of the Department of Transportation (http://dms.dot.gov/).

(2) On that page, click on “search.”

(3) On the next page (http://dms.dot.gov/search/),, type in the four-digit docket number shown at the beginning of this document. Example: If the docket number were “NHTSA-1998-1234,” you would type “1234.” After typing the docket number, click on “search.”

(4) On the next page, which contains docket summary information for the docket you selected, click on the desired comments. You can then download the comments.

Please note that even after the comment closing date, we will continue to file relevant information in the Docket as it becomes available. Further, some people may submit late comments. Accordingly, we recommend that you periodically check the Docket for new material.