Federal Motor Vehicle Safety Standards, Ejection Mitigation; Phase-In Reporting Requirements; Incorporation by Reference

DEPARTMENT OF TRANSPORTATION

National Highway Traffic Safety Administration

49 CFR Parts 571 and 585

[Docket No. NHTSA-2011-0004]

RIN 2127-AK23

Federal Motor Vehicle Safety Standards, Ejection Mitigation; Phase-In Reporting Requirements; Incorporation by Reference

AGENCY:

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

ACTION:

Final rule.

SUMMARY:

This final rule establishes a new Federal Motor Vehicle Safety Standard No. 226, “Ejection Mitigation,” to reduce the partial and complete ejection of vehicle occupants through side windows in crashes, particularly rollover crashes. The standard applies to the side windows next to the first three rows of seats, and to a portion of the cargo area behind the first or second rows, in motor vehicles with a gross vehicle weight rating (GVWR) of 4,536 kilogram (kg) or less (10,000 pounds (lb) or less). To assess compliance, the agency is adopting a test in which an impactor is propelled from inside a test vehicle toward the windows. The ejection mitigation safety system is required to prevent the impactor from moving more than a specified distance beyond the plane of a window. To ensure that the systems cover the entire opening of each window for the duration of a rollover, each side window will be impacted at up to four locations around its perimeter at two time intervals following deployment.

The agency anticipates that manufacturers will meet the standard by modifying existing side impact air bag curtains, and possibly supplementing them with advanced glazing. The curtains will be made larger so that they cover more of the window opening, made more robust to remain inflated longer, and made to deploy in both side impacts and in rollovers. In addition, after deployment the curtains will be tethered near the base of the vehicle's pillars or otherwise designed to keep the impactor within the boundaries established by the performance test. This final rule adopts a phase-in of the new requirements, starting September 1, 2013.

This final rule advances NHTSA's initiatives in rollover safety and also responds to Section 10301 of the Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (SAFETEA-LU). That section directs NHTSA to initiate and complete rulemaking to reduce complete and partial ejections of vehicle occupants from outboard seating positions, considering various ejection mitigation systems.

DATES:

Effective date:

The date on which this final rule amends the Code of Federal Regulations (CFR) is March 1, 2011. The incorporation by reference of certain publications listed in the standard is approved by the Director of the Federal Register as of March 1, 2011.

Petitions for reconsideration:

If you wish to petition for reconsideration of this rule, your petition must be received by March 7, 2011.

Compliance dates:

This final rule adopts a phase-in of the new requirements. The phase-in begins on September 1, 2013. By September 1, 2017, all vehicles must meet the standard, with the exception of altered vehicles and vehicles produced in more than one stage, which are provided more time to meet the requirements. Manufacturers can earn credits toward meeting the applicable phase-in percentages by producing compliant vehicles ahead of schedule, beginning March 1, 2011 and ending at the conclusion of the phase-in.

ADDRESSES:

If you wish to petition for reconsideration of this rule, you should refer in your petition to the docket number of this document and submit your petition to: Administrator, National Highway Traffic Safety Administration, 1200 New Jersey Avenue, SE., West Building, Washington, DC 20590.

The petition will be placed in the docket. Anyone is able to search the electronic form of all documents received into any of our dockets by the name of the individual submitting the comment (or signing the comment, if submitted on behalf of an association, business, labor union, etc.). You may review DOT's complete Privacy Act Statement in the

Federal Register

published on April 11, 2000 (Volume 65, Number 70; Pages 19477-78).

For access to the docket to read background documents or comments received, go to

http://www.regulations.gov

and follow the online instructions for accessing the docket. You may also visit DOT's Docket Management Facility, 1200 New Jersey Avenue, SE., West Building Ground Floor, Room W12-140, Washington, DC 20590-0001 for on-line access to the docket.

FOR FURTHER INFORMATION CONTACT:

For non-legal issues, you may contact Mr. Louis Molino, NHTSA Office of Crashworthiness Standards, telephone 202-366-1740, fax 202-493-2739. For legal issues, you may contact Ms. Deirdre Fujita, NHTSA Office of Chief Counsel, telephone 202-366-2992, fax 202-366-3820.

You may send mail to these officials at the National Highway Traffic Safety Administration, U.S. Department of Transportation, 1200 New Jersey Avenue, SE., West Building, Washington, DC 20590.

SUPPLEMENTARY INFORMATION:

Table of Contents

I. Executive Summary

II. Safety Need

III. Congressional Mandate

IV. Summary of the NPRM

V. Summary of the Comments

VI. How the Final Rule Differs From the NPRM

VII. Foundations for This Rulemaking

a. Advanced Glazing

b. Full Window Opening Coverage Is Key

c. Comparable Performance in Simulated Rollovers and Component-Level Impact Tests

d. Advantages of a Component Test Over a Full Vehicle Dynamic Test

VIII. Availability of Existing Curtains

IX. Existing Curtains

a. Existing Curtains Tested to Proposed Requirements

b. Field Performance

X. Response to Comments and Agency Decisions

a. Impactor Dimensions and Mass

1. NPRM

2. Comments

3. Agency Response

b. Measurement Plane and Displacement Limit (100 mm)

1. NPRM

2. Comments

3. Agency Response

c. Times and Speed at Which the Headform Impacts the Countermeasure

1. NPRM on Time Delay (Ejections Can Occur Both Early and Late in the Rollover Event)

i. Comments on Time Delay

ii. Agency Response

2. Speed at Which the Headform Impacts the Countermeasure

i. Comments on Impact Speed

ii. Agency Response

d. Target Locations

1. Why We Are Focusing on Side Windows and Not Other Openings

2. Why We Are Focusing on the Side Windows Adjacent to First Three Rows

i. First Three Rows

ii. Method of Determining 600 mm Behind Seating Reference Point (SgRP)

iii. Increasing 600 mm Limit for Vehicles With One or Two Rows of Seats

3. Answers to Questions About Method for Determining Three-Row Area

e. How We Are Testing the Ability of These Side Windows To Mitigate Ejections

1. What is a “window opening”?

i. 50 mm Inboard of the Glazing

ii. Conducting the Test With Various Items Around the Window Opening

iii. Removing Flexible Gasket Material

iv. Testing With Weather Stripping in Place

v. Metal Dividers in Glazing

2. How We Determine Impactor Target Locations in an Objective and Repeatable Manner

i. Testing in ”Any” Location

ii. Methodology

iii. Reorienting the Targets

iv. Suppose Even With Rotating the Headform the Vehicle Has No Target Locations

v. Decision Not To Test Target of Greatest Displacement

vi. Reconstitution of Targets

f. Glazing Issues

1. Positioning the Glazing

2. Window Pre-Breaking Specification and Method

g. Test Procedure Tolerances

h. Impactor Test Device Characteristics

i. Readiness Indicator

j. Other Issues

1. Rollover Sensors

2. Quasi-Static Loading

3. Full Vehicle Test

4. Minor Clarifications to the Proposed Regulatory Text

k. Practicability

l. Applicability

1. Convertibles

2. Original Roof Modified

3. Multi-Stage Manufacture of Work Trucks

4. Other

m. Lead Time and Phase-In Schedules; Reporting Requirements

XI. Costs and Benefits

XII. Rulemaking Analyses and Notices

I. Executive Summary

This final rule establishes a new Federal Motor Vehicle Safety Standard (FMVSS) No. 226, “Ejection Mitigation,” to reduce the partial and complete ejection of vehicle occupants through side windows in crashes, particularly rollover crashes. Countermeasures installed to meet this rule will also reduce the number of complete and partial ejections of occupants in side impacts. This final rule responds to section 10301 of the Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users,” (SAFETEA-LU), Public Law 109-59 (Aug. 10, 2005; 119 Stat. 1144), which requires the Secretary of Transportation to issue an ejection mitigation final rule reducing complete and partial ejections of occupants from outboard seating positions.

Addressing vehicle rollovers is one of NHTSA's highest safety priorities. In 2002, NHTSA conducted an in-depth review of rollovers and associated deaths and injuries and assessed how this agency and the Federal Highway Administration (FHWA) could most effectively improve safety in this area.

1

The agency formulated strategies involving improving vehicle performance and occupant behavior, and with the FHWA taking the lead, improving roadway designs. Vehicle performance strategies included crash avoidance and crashworthiness programs, and included four wide-ranging initiatives to address the rollover safety problem: prevent crashes, prevent rollovers, prevent ejections, and protect occupants who remain within the vehicle after a crash. Projects aimed at protecting occupants remaining in the vehicle during a rollover included improved roof crush resistance and research on whether seat belts could be made more effective in rollovers.

1

The assessment was carried out by one of four Integrated Project Teams (IPTs) formed within NHTSA, whose recommendations culminated in the agency's priority plan, “NHTSA Vehicle Safety Rulemaking and Supporting Research: 2003-2006” (68 FR 43972; July 18, 2003)

http://www.nhtsa.dot.gov/cars/rules/rulings/PriorityPlan/FinalVeh/Index.html.

The IPT Report on Rollover was published in June 2003 (68 FR 36534, Docket 14622).

A major undertaking implementing the first two initiatives was completed in 2007 when NHTSA adopted a new FMVSS No. 126 (49 CFR 571.126), “Electronic Stability Control Systems,” to require electronic stability control (ESC) systems on passenger cars, multipurpose passenger vehicles, trucks, and buses with a gross vehicle weight rating (GVWR) of 4,536 kg (10,000 lb) or less (72 FR 17236, April 6, 2007, Docket NHTSA-2007-27662). ESC systems use automatic computer-controlled braking of the individual wheels of a vehicle to assist the driver in maintaining control in critical driving situations in which the vehicle is beginning to lose directional stability at the rear wheels (spin out) or directional control at the front wheels (plow out). Because most loss-of-control crashes culminate in the vehicle's leaving the roadway—an event that significantly increases the probability of a rollover—preventing single-vehicle loss-of-control crashes is the most effective way to reduce deaths resulting from rollover crashes.

2

The agency estimates that when all vehicles (other than motorcycles) under 4,536 kg GVWR have ESC systems, the number of deaths each year resulting from rollover crashes would be reduced by 4,200 to 5,500. From 2001 to 2007, there were more than 10,000 deaths in light vehicle rollover crashes. Rollover deaths have decreased slightly in 2008 (9,043) and 2009 (8,267), as have fatalities in all crash types.

2

NHTSA estimates that the installation of ESC will reduce single-vehicle crashes of passenger cars by 34 percent and single vehicle crashes of sport utility vehicles (SUVs) by 59 percent. NHTSA further estimates that ESC has the potential to prevent 71 percent of the passenger car rollovers and 84 percent of the SUV rollovers that would otherwise occur in single-vehicle crashes. NHTSA estimates that ESC would save 5,300 to 9,600 lives and prevent 156,000 to 238,000 injuries in all types of crashes annually once all light vehicles on the road are equipped with ESC systems.

While ESC systems will avoid many of the roadway departures that lead to rollover, vehicle rollovers will continue to occur.

3

Once a rollover occurs, vehicle crashworthiness characteristics play a crucial role in protecting the occupants. According to agency data, occupants have a much better chance of surviving a crash if they are not ejected from their vehicles.

3

NHTSA has developed a Final Regulatory Impact Analysis (FRIA) for this final rule that discusses issues relating to the target population and the potential costs, benefits and other impacts of this regulatory action. The FRIA is available in the docket for this final rule and may be obtained by downloading it or by contacting the Docket Management facility at the address provided at the beginning of this document.

Concurrent with the agency's work on ESC, NHTSA began work on the third initiative on rollover safety, pursuing the feasibility of installing crashworthiness safety systems to mitigate occupant ejections through side windows in rollovers (“ejection mitigation”). Major strides on this third initiative were realized in 2007 when the agency published a final rule that incorporated a dynamic pole test into FMVSS No. 214, “Side impact protection” (49 CFR 571.214) (“Phase 1 FMVSS No. 214 rulemaking”).

4

The pole test, applying to motor vehicles with a GVWR of 4,536 kg or less, requires vehicle manufacturers to provide side impact protection for a wide range of occupant sizes and over a broad range of seating positions. To meet the pole test, manufacturers are installing new technologies capable of improving head and thorax protection in side crashes, i.e., side curtain air bags and torso air bags.

4

72 FR 51908; September 11, 2007, Docket No. NHTSA-29134; response to petitions for reconsideration, 73 FR 32473, June 9, 2008, Docket No. NHTSA-2008-0104, 75 FR 12123, March 15, 2010, Docket No. NHTSA-2010-0032. On August 10, 2005, the “Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users,” (SAFETEA-LU), Public Law 109-59 (Aug. 10, 2005; 119 Stat. 1144) was enacted, to authorize funds for Federal-aid highways, highway safety programs, and transit programs, and for other purposes. Section 10302(a) of SAFETEA-LU directed the Secretary to complete the FMVSS No. 214 rulemaking by July 1, 2008. The September 11, 2007 final rule completed the rulemaking specified in section 10302(a). NHTSA estimates that the September 11, 2007 final rule will save 311 lives annually.

Today's final rule launches a new phase in occupant protection and ejection mitigation. It builds on and

improves existing technology while achieving cost efficiency and does so expeditiously. This final rule enhances the side curtain air bag systems installed pursuant to the FMVSS No. 214 side impact rulemaking. Side curtain air bags

5

will be made larger to cover more of the window opening, more robust to remain inflated longer, enhanced to deploy in side impacts and in rollovers, and made not only to cushion but also made sufficiently strong to keep an occupant from being fully or partially ejected through a side window. The side curtain air bags required by this rule will be designed to retain the occupant regardless of whether the occupant had his or her window glazing up, down, or partially open, and even when the glazing is destroyed during the rollover crash.

5

In this document, this countermeasure is referred to as an “ejection mitigation side curtain air bag,” “side curtain air bag,” “air bag curtain,” “rollover curtain,” or simply “curtain.” This countermeasure is designed to deploy in a rollover crash. The same side curtain air bag meeting FMVSS No. 226 can be used to meet the ejection mitigation requirements of FMVSS No. 214 with the addition of a rollover sensing system to deploy the side curtain air bag in a rollover.

The NPRM upon which this final rule is based was published on December 2, 2009 (74 FR 63180, Docket No. NHTSA-2009-0183). Materials underlying the development of this rule have been placed in that docket and in a research and development docket created in 2006 (Docket No. NHTSA-2006-26467).

Rollover crashes can be complex and unpredictable. At this time there is no conventional rollover scenario or test representative of real-world rollover crashes that can be used in a dynamic test to the agency's satisfaction to evaluate the performance of ejection mitigation countermeasures. Yet, this final rule achieves ejection mitigation benefits notwithstanding the absence of a dynamic procedure. Agency research has found that full coverage of the side windows is a key element to mitigating ejection. This standard adopts a component test that assures there is full coverage of the side window to diminish the potential risk of the windows as ejection portals and that assesses ejection mitigation safety systems for as long in the crash event as the risk of ejection reasonably exists.

The test uses a guided impactor to assess the ability of the countermeasure (

e.g.,

a curtain system) to mitigate ejections in different types of rollover and side impact crashes involving different occupant kinematics. The test has been carefully designed to represent occupant to vehicle interactions in a dynamic rollover event. The impact mass is based on the mass imposed by a 50th percentile male's head and upper torso on the window opening during an occupant ejection. The mass of the impactor, 18 kilograms (kg) (40 lb), is propelled at points around the window's perimeter with sufficient kinetic energy to assure that the ejection mitigation countermeasure is able to protect a far-reaching range of occupants in real world crashes.

In the test, the countermeasure must retain the linear travel of the impactor such that the impactor must not travel 100 millimeters (mm) beyond the location of the inside surface of the vehicle glazing. This displacement limit serves to control the size of any gaps forming between the countermeasure (

e.g.,

the ejection mitigation side curtain air bag) and the window opening, thus reducing the potential for both partial and complete ejection of an occupant.

To evaluate the performance of the curtain to fully cover potential ejection routes, the impactor will typically target four specific locations per side window adjacent to the first three rows of the vehicle. Impacting four targets around the perimeter of the opening assures that the window will be covered by the countermeasure (curtain), while imposing a reasonable test burden. Small windows will be tested with fewer targets.

Computer modeling has shown that ejections can occur early and late in the rollover event. In the standard's test procedure, the ejection mitigation side countermeasure will be tested at two impact speeds and at two different points in time, to ensure that the protective system will retain the occupant from the relatively early through the late stages of a rollover.

The times at which the impacts will occur are data-driven and related to our goal of containment of occupants both early and late in rollovers. Crash data show that slightly less than half of all fatal complete ejections occurred in crashes with 5 or fewer quarter-turns. Film analysis of vehicles that rolled 5 or fewer quarter-turns in staged rollover tests indicates that it took about 1.5 seconds for the vehicles to roll once completely. A vehicle rolling 11 quarter-turns had a maximum roll time of 5.5 seconds. Data from the National Automotive Sampling System (NASS) Crashworthiness Data System (CDS) show that rollovers with eleven or fewer quarter-turns account for about 98 percent of rollovers with fatal complete ejection.

6

The standard replicates these crash dynamics with the two impacts of the headform. The first impact will be at 20 kilometers per hour (km/h) (12.4 miles per hour (mph)), 1.5 seconds after deployment of the curtain. The second impact will be at 16 km/h (9.9 mph), 6 seconds after deployment of the curtain. The 20 km/h and 16 km/h tests replicate the forces that an occupant can impart to the curtain during the rollover event as well as during side impacts.

6

This is based on 2000-2009 NASS data. The 1988—2005 NASS data reported in the NPRM showed that 93 percent of rollovers with fatal complete ejections had 11 or fewer quarter-turns.

Under today's final rule, vehicle manufacturers must provide information to NHTSA upon request that describes the conditions under which ejection mitigation air bags will deploy. There is no presently demonstrated need for us to specify in the standard the conditions dictating when the sensors should deploy; field data indicate that rollover sensors are overwhelmingly deploying effectively in the real world. We will keep monitoring field data to determine whether future regulatory action is needed in this area.

This chapter in occupant protection will achieve tremendous benefits at reasonable costs. We estimate that this rule will save 373 lives and prevent 476 serious injuries per year (see Table 1 below). The cost of this final rule is approximately $31 per vehicle (see Table 2). The cost per equivalent life saved is estimated to be $1.4 million (3 percent discount rate)-$1.7 million (7 percent discount rate) (see Table 3 below). Annualized costs and benefits are provided in Table 4.

Table 1—Estimated Benefits

Fatalities

373

Serious Injuries

476

Table 2—Estimated Costs*

[2009 economics]

Per Vehicle

$31.

Total Fleet (16.5 million vehicles)

$507 Million

* The system costs are based on vehicles that are equipped with an FMVSS No. 214 curtain system. According to vehicle manufacturers' projections made in 2006, 98.7 percent of Model Year (MY) 2011 vehicles will be equipped with curtain bags and 55 percent of vehicles with curtain bags will be equipped with a rollover sensor.

Table 3—Cost per Equivalent Life Saved

3% Discount rate

7% Discount rate

$1.4M

$1.7M

Table 4—Annualized Costs and Benefits

[In millions of $2009 dollars]

Annual costs

Annualized benefits

Net benefits

3% Discount Rate

$507M

$2,279M

$1,773

7% Discount Rate

507M

1,814M

1,307

Accompanying today's final rule is a Final Regulatory Impact Analysis (FRIA) analyzing the costs, benefits, and other impacts of this final rule, and a technical report the agency has prepared that presents a detailed analysis of engineering studies, and other information supporting the final rule. Both documents have been placed in the docket for this final rule. The documents can be obtained by contacting the docket by the means specified at the beginning of this document or by downloading them at www.regulations.gov.

II. Safety Need

Rollover crashes are a significant and a particularly deadly safety problem. As a crash type, rollovers are second only to frontal crashes as a source of fatalities in light vehicles. Data from the last 10 years of Fatal Analysis Reporting System (FARS) files (2000-2009

7

) indicate that frontal crash fatalities have averaged about 11,600 per year, while rollover fatalities have averaged 10,037 per year. In 2009, 35 percent of all fatalities were in light vehicle rollover crashes. The last 10 years of data from the National Automotive Sampling System (NASS) General Estimates System (GES) indicate that an occupant in a rollover is 14 times more likely to be killed than an occupant in a frontal crash.

8

7

These data are updated from the 1998 to 2007 FARS data reported in the NPRM.

8

The relative risk of fatality for each crash type can be assessed by dividing the number of fatalities in each crash type by the frequency of the crash type. The frequency of particular crash types is determined by police traffic crash reports (PARs).

Ejection is a major cause of death and injury in rollover crashes. According to 2000-2009 FARS data, on average 47 percent of the occupants killed in rollovers were completely ejected from their vehicle. During this time period, there were 358 fully ejected occupants killed for every 1,000 fully ejected occupants in rollover crashes, as compared to 14 of every 1,000 occupants not fully ejected occupants killed.

9

A double-pair comparison from the last ten years of FARS data show that avoiding complete ejection is associated with a 64 percent decrease in the risk of death.

10

9

The data combines partially-ejected and un-ejected occupants together, because partial ejection is sometimes difficult to determine and the PAR-generated FARS data may not be an accurate representation of partially-ejected occupant fatalities.

10

“Incremental Risk of Injury and Fatality Associated with Complete Ejection,” NHTSA, 2010 (see the docket for this final rule).

The majority of rollover crashes involve the vehicle rolling over two quarter-turns or less. However, the distribution of ejected occupants who are seriously injured (maximum abbreviated injury scale (MAIS) 3+) or killed is skewed towards rollovers with a higher number of quarter-turns. According to NASS Crashworthiness Data System (CDS) data of occupants exposed to a rollover crash from 2000 to 2009, half of all fatal complete ejections occurred in crashes with six or more quarter-turns.

Most occupants are ejected through side windows. In developing the target population estimates for this final rule we found that annualized injury data from 1997 to 2008 NASS CDS and fatality counts adjusted to the annual average from FARS for these same years

11

indicate that ejection through side windows is the greatest contributor to the ejection problem.

12

There were 16,272 MAIS 1-2 injuries, 5,209 MAIS 3-5 injuries, and 6,412 fatalities resulting from ejections through the side windows adjacent to the first three rows.

11

The target population estimate for the NPRM used 1997 to 2005 FARS data. The estimate for this final rule is based on an additional three years of data.

12

In our data analysis for the NPRM to determine ejection routes, we assumed that an ejection route coding of “rear” in NASS CDS meant a second row window and that “other” glazing meant third and higher row side window ejections. The assumption was based on the coding of seat position in NASS. Since then, we have determined that an occupant coded as ejected through a “rear” window did not necessarily go through the second row window. Similarly, the coding of “other” glazing was determined not necessarily to mean third and higher row. Thus, for this final rule, for cases coded as ejected through “rear” or “other” glazing, we assume that the ejection was through a second row window in the following circumstances: the occupant was seated in the first two rows of a vehicle, or the vehicle was a convertible, two-door sedan, or four-door sedan (i.e., these are vehicles without a third row or cargo area). If an occupant was coded as seated in the third or higher row and was coded as ejected through a rear window or “other” glazing, we used the NASS Case Query System to undertake a hard copy review. We determined ejection routes in this manner for 41 unweighted rear window cases and 17 unweighted “other” glazing cases. A hard copy review of the “other” glazing cases showed that 9 were known 3rd row side window ejections, but five cases were miscoded. Four were actually backlight ejections and one was a sunroof ejection. The known 3rd row ejections were recoded as “Row 3 Window” ejections.

Table 5 below shows the MAIS 1-2, MAIS 3-5, and fatality distribution of ejected occupants by 11 potential ejection routes.

13

The “Not Glazing” category captures ejected occupants that did not eject through a glazing area or the roof (perhaps a door or an area of vehicle structure that was torn away during the crash). Roof ejections have been separated into “Roof Panel or Glazing” and “Roof Other.” The former groups sunroofs, t-tops and targa-tops into a single category, whether made of glazing or having a sheet metal skin. The latter combines convertibles, modified roofs, camper tops and removable roofs. No distinction could be made as to whether these roof structures were open or closed prior to ejection.

13

All crash types are included, but the counts are restricted to ejected occupants who were injured.

Table 5—Occupant Injury and Fatality Counts by Ejection Route in All Crash Types

[Annualized 1997-2008 NASS and FARS]

Ejection route

MAIS 1-2

MAIS 3-5

Fatal

Windshield

1,517

1,400

1,078

First-Row Windows

14,293

4,980

5,589

Second-Row Windows

1,700

641

796

Third-Row Windows

279

88

27

Fourth-Row Windows

0

0

39

Fifth-Row Window

0

0

7

Cargo Area Rear of Row 2

342

17

52

Backlight

1,621

1,364

495

Roof Panel or Glazing

1,000

367

324

Roof Other

420

105

81

Multiple Windows

0

19

0

Not Glazing

2,848

2,207

1,814

Subtotals:

Rows 1-3

16,272

5,709

6,412

4th, 5th Row and Cargo

342

17

98

Total

24,020

11,188

10,302

Table 6, below, provides the percentage of the total at each injury level. The injuries and fatalities resulting from ejections through the first three rows of windows constitute 68 percent of MAIS 1-2 injuries, 51 percent of MAIS 3-5 injuries, and 62 percent of all ejected fatalities.

Table 6—Occupant Injury and Fatality Percentages by Ejection Route in All Crash Types

[Annualized 1997-2008 NASS and FARS]

Ejection route

MAIS 1-2

MAIS 3-5

Fatal

Windshield

6.3%

12.5%

10.5%

First-Row Windows

59.5%

44.5%

54.2%

Second-Row Windows

7.1%

5.7%

7.7%

Third-Row Windows

1.2%

0.8%

0.3%

Fourth-Row Windows

0.0%

0.0%

0.4%

Fifth-Row Window

0.0%

0.0%

0.1%

Cargo Area Rear of Row 2

1.4%

0.2%

0.5%

Backlight

6.8%

12.2%

4.8%

Roof Panel or Glazing

4.2%

3.3%

3.1%

Roof Other

1.7%

0.9%

0.8%

Multiple Windows

0.0%

0.2%

0.0%

Not Glazing

11.9%

19.7%

17.6%

Subtotals:

Rows 1-3

67.7%

51.0%

62.2%

4th, 5th Row and Cargo

1.4%

0.2%

1.0%

Total

100.0%

100.0%

100.0%

Since the countermeasure covering side window openings will be made more effective in preventing ejections, this rulemaking will also reduce the number of complete and partial ejections of occupants in side impacts. These benefits go beyond those achieved in the rulemaking adopting an oblique pole test into FMVSS No. 214 (Phase 1 FMVSS No. 214 rulemaking) because a side air bag installed to meet FMVSS No. 214 is not necessarily wide or robust enough to effectively contain occupants in certain side impacts. In fact, NHTSA found that FMVSS No. 214's requirements could be met by a seat-mounted head/torso side air bag or a side head protection curtain air bag together with a seat-mounted or door-mounted torso bag. Further, FMVSS No. 214's pole test does not apply to rear seats. In short, FMVSS No. 214 does not require the large curtain needed for full coverage of side window openings.

Accordingly, this ejection mitigation safety standard will reduce the number of partial and complete ejections of occupants in side impacts. The Phase 1 FMVSS No. 214 rulemaking included reduction of partial ejections of adults (age 13+ years) through side windows in side impacts, but did not include complete ejections. The Phase 1 side impact rulemaking also did not include any impact where a rollover was the first event. In addition, benefits were only assumed in the Phase 1 FMVSS No. 214 rulemaking for side impact crashes with a change in velocity (ΔV) between 19.2 and 40.2 km/h (12 to 25 mph) and impact directions from 2 to 3 o'clock and 9 to 10 o'clock. The side curtain air bags used to meet FMVSS No. 226's ejection mitigation requirements will directly prevent many ejection-induced injuries and fatalities in side impacts that could not be saved by a side air bag that minimally complies with FMVSS No. 214.

Target Population

In general, the target population for this ejection mitigation final rule is composed of occupants injured or killed by ejection from the first three rows of side windows in vehicles to which the standard applies. Later in the preamble, we discuss some slight adjustments made concerning occupants ejected through cargo area window openings.

The target population does not include occupants ejected in all crash types, but rather is restricted to ejections that occur in crashes involving rollovers and some types of planar only side impacts. The limitation on side impacts, change in velocity (ΔV), and certain occupants in those side impacts is necessary to not count benefits anticipated by FMVSS No. 214.

Tables 7-9 provide the counts and/or percentages of the injured and killed side window (rows 1-3) ejected occupants by the window row they were ejected through. These data are restricted to rollover crashes and side impacts in the relevant ΔV range (target population type crashes).

Tables 7 and 8 show the ejection degree and restraint condition for occupants in the first three rows of target population type crashes. Among the side windows, the first row windows provide the ejection route for most of the injured and killed occupants. The greatest number of fatally ejected occupants (3,837) went through the first row window. This represents 88 percent of all side window ejected fatalities. Similarly, 3,979 (89 percent) MAIS 3-5 and 10,017 (87 percent) MAIS 1-2 injured occupants went through the row 1 windows. Within each row, the greatest number of fatal and MAIS 3-5 occupants were completely ejected and unbelted. There were 2,623 fatally injured (59 percent) and 2,269 MAIS 3-5 injured (50 percent) occupants who were unbelted and completely ejected through the row 1 windows.

Table 7—Distribution of First 3 Rows of Side Window Ejected Occupants by Ejection Row and Injury Level by Ejection Degree and Belt Use, In Target Population Type Crashes

[Annualized 1997-2008 NASS and FARS]

Ejection degree

Belted

Row 1

MAIS

1-2

MAIS

3-5

Fatal

Row 2

MAIS

1-2

MAIS

3-5

Fatal

Row 3

MAIS

1-2

MAIS

3-5

Fatal

Complete

Yes

95

29

54

139

78

5

0

8

0

Complete

No

3,501

2,269

2,623

782

309

421

95

54

23

Partial

Yes

4,345

1,097

484

43

32

38

109

0

0

Partial

No

2,076

584

675

103

80

123

4

0

0

Total

10,017

3,979

3,837

1,067

499

587

207

62

23

Table 8—Distribution of First 3 Rows of Side Window Ejected Occupants by Ejection Row and Injury Level by Ejection Degree and Belt Use, as a Percentage of Totals at each Injury Level, in Target Population Type Crashes

Ejection degree

Belted

Row 1

MAIS

1-2

MAIS

3-5

Fatal

Row 2

MAIS

1-2

MAIS

3-5

Fatal

Row 3

MAIS

1-2

MAIS

3-5

Fatal

Complete

Yes

1%

1%

1%

1%

2%

0%

0%

0%

0%

Complete

No

31%

50%

59%

7%

7%

9%

1%

1%

1%

Partial

Yes

38%

24%

11%

0%

1%

1%

1%

0%

0%

Partial

No

18%

13%

15%

1%

2%

3%

0%

0%

0%

Total

87%

89%

88%

86%

9%

11%

13%

2%

1%

Table 9 shows the ejection degree and vehicle type for occupants in the first three rows of target population type crashes. The greatest numbers of fatalities result from occupants completely ejected from passenger cars. These account for 28 percent of the total fatalities.

Combining partial and complete ejections, cars account for 43 percent of fatalities and 42 percent of MAIS 3 to 5 injuries. Pickup trucks and sport utility vehicles (SUVs) combined account for 50 percent of fatalities and 54 percent of MAIS 3 to 5 injuries. Since the early 1990s, the SUV segment has provided an increasing proportion of rollover fatalities. SUVs represented approximately 16 percent of fatalities in 1997, and nearly 27 percent in 2008. Vans comprise 7 percent of the fatalities and 4 percent of the MAIS 3-5 ejections.

Table 9—Distribution of Fatalities and Injuries of First 3 Rows Side Window Ejected Occupants By Vehicle Type

[Annualized 1997—2008 NASS and FARS]

Vehicle

MAIS 1-2

MAIS 3-5

Fatal

MAIS 1-2

MAIS 3-5

Fatal

Complete Ejections

Car

1,158

928

1,239

10%

20%

28%

PU

1,236

812

793

11%

18%

18%

SUV

1,881

858

907

17%

19%

20%

Van

324

147

188

3%

3%

4%

Other

12

2

0

0%

0%

0%

Subtotal

4,612

2,747

3,127

41%

61%

70%

Partial Ejections

Car

1,429

971

660

13%

21%

15%

PU

2,515

375

190

22%

8%

4%

SUV

1,590

402

350

14%

9%

8%

Van

1,133

44

103

10%

1%

2%

Other

13

0

17

0%

0%

0%

Subtotal

6,680

1,793

1,320

59%

39%

30%

Total Ejections

Car

2,588

1,899

1,899

23%

42%

43%

PU

3,750

1,187

983

33%

26%

22%

SUV

3,471

1,260

1,257

31%

28%

28%

Van

1,457

192

291

13%

4%

7%

Other

25

2

17

0%

0%

0%

Total

11,292

4,540

4,447

100%

100%

100%

In summary, for the most part, the target population for this ejection mitigation final rule is composed of occupants injured or killed in an ejection from the first three rows of side windows in vehicles to which the standard applies. The target population does not include the population addressed by the Phase 1 FMVSS No. 214 rulemaking, and does not include persons benefited by the installation of ESC systems in vehicles. (We assume that all model year 2011 vehicles and thereafter will be equipped with ESC, see FMVSS No. 126.) As adjusted for ESC, the target population for this ejection mitigation rulemaking is reduced to 1,392 fatalities, 1,410 MAIS 3-5 injuries and 4,217 MAIS 1-2 injuries. This target population constitutes 23 percent of fatally-injured occupants ejected through a side window, 27 percent of MAIS 3-5 injured, and 23 percent of MAIS 1-2 injured side window-ejected occupants.

14

14

When discussing the target population in this preamble, we will typically mean the pre-ESC adjusted values. We will specifically state when we are referring to an ESC-adjusted target population.

III. Congressional Mandate

This final rule responds to section 10301 of SAFETEA-LU, which requires the Secretary of Transportation to issue an ejection mitigation final rule reducing complete and partial ejections of occupants from outboard seating positions. Section 10301 amended Subchapter II of chapter 301 (49 U.S.C. Chapter 301, National Traffic and Motor Vehicle Safety Act) (“Vehicle Safety Act”) to add section 30128. Section 10301, paragraph (a), directs the Secretary to initiate rulemaking proceedings, for the purpose of establishing rules or standards that will reduce vehicle rollover crashes and mitigate deaths and injuries associated with such crashes for motor vehicles with a GVWR of not more than 10,000 pounds. Paragraph (c) directs the Secretary to initiate a rulemaking proceeding to establish performance standards to reduce complete and partial ejections of vehicle occupants from outboard seating positions and that, in formulating the standards, the Secretary shall consider various ejection mitigation systems.

15

15

Paragraph (c) states that the Secretary shall issue a final rule under this paragraph by October 1, 2009. Paragraph (e) states that if the Secretary determines that the subject final rule deadline cannot be met, the Secretary shall notify and provide explanation to the Senate Committee on Commerce, Science, and Transportation and the House of Representatives Committee on Energy and Commerce of the delay. On September 24, 2009, the Secretary notified Congress that the final rule will be delayed until January 31, 2011.

NHTSA's final rule fulfills the statutory mandate of section 10301 of SAFETEA-LU to issue an ejection mitigation final rule reducing complete and partial ejections of occupants from outboard seating positions. We have considered various ejection mitigation systems, including advanced glazing,

16

and have made appropriate decisions based on that analysis. At the time of its implementation this final rule will reduce fatality ejected occupants by about one third

17

and completes a decisive stage in the agency's rollover crashworthiness program.

16

One type of advanced glazing systems, usually referred to as laminated glazing, has a multi-layer construction typically with three primary layers. There is usually a plastic laminate bonded between two pieces of glass. Advanced glazing was considered in the 1990s to have potential for use in ejection mitigation.

17

This fatality reduction does not double-count benefits from ESC and the recent FMVSS No. 214 upgrade.

A few glazing manufacturers, a glazing manufacturers' association, and two consumer groups expressed a view in their comments to the NPRM that the rulemaking will fall short of the statutory mandate unless the final rule ensured that windows will not allow any openings larger than two inches to form during a rollover event (as a consequence, such a requirement would encourage the use of advanced glazing). These commenters also believed that SAFETEA-LU directed NHTSA to address ejections through sun roofs, moon roofs,

18

and rear windows in this standard. We address these comments in detail in later sections of this preamble.

18

For this document, we refer to movable and fixed roof panels made of glazing as “moon roofs” and movable panels having a sheet metal exterior as “sun roofs.” We refer to both as roof portals.

With regard to the general assertion that this rulemaking does not meet SAFETEA-LU, we cannot agree. As part and parcel of good governance, all safety standards must be reasonable and appropriate. In addition, in adding section 30128 to the Vehicle Safety Act, SAFETEA-LU specifically requires us to issue an ejection mitigation final rule in accordance with the criteria of that Act. The Vehicle Safety Act requires each motor vehicle safety standard to be practicable, meet the need for motor vehicle safety, and be stated in objective terms. (49 U.S.C. 30111(a).) We must also consider whether the standard is reasonable, practicable, and appropriate for the particular type of motor vehicle or motor vehicle equipment for which it is prescribed. (49 U.S.C. 30111(b)(3).)

This final rule requires protective barriers at side windows, the ejection

portals through which 62 percent of occupants are fatally ejected in all crash types. We did not adopt the suggestions in the comments of the glazing manufacturers that could have bolstered increased use of advanced glazing in side windows because we did not find a safety need supporting the approaches. For back windows (backlight) and roof portals, we found that not enough was known to appropriately evaluate the costs, benefits and practicability of the requirements, at this time, including the lack of a viable test procedure. (Fatal ejections through the back light and roof portals account for 4.8 and 3.9 percent of fatal ejections in all crash types.) An appropriate test procedure that would assess ejection potential through portals on the vehicle's roof is also unknown.

In formulating this final rule, NHTSA considered various ejection mitigation systems in accordance with section 10301 of SAFETEA-LU. We sought to adopt performance measures that were design-neutral and performance-oriented so as to provide substantial flexibility to vehicle manufacturers in developing or enhancing ejection mitigation countermeasures that meet the requirements of the standard. To illustrate, the headform test procedure was originally developed in the advanced glazing research program and can be used to assess the performance of many different types of countermeasures at the side windows. The final rule recognizes the beneficial effect advanced glazing can have and permits the use of fixed glazing to achieve the performance criteria specified in the standard. At the same time, however, NHTSA determined after considering real-world field data on advanced glazing that movable advanced glazing alone would not be a satisfactory ejection mitigation countermeasure for side window openings, given that 31 percent of front seat ejections are through windows that were partially or fully rolled down, and given that it is not unusual for advanced glazing to be heavily damaged and rendered ineffective in a rollover crash. Accordingly, the standard does not permit use of movable glazing alone to meet the requirements of the standard. Movable glazing may be used in the high speed test, but it must be used in conjunction with a deployable safety system that will mitigate ejection throughout the stages of a rollover event, such as an ejection mitigation side curtain air bag.

In directing us to consider various ejection mitigation systems, there is indication that Congress envisioned us focusing on ejections through side windows. At the time of enactment of SAFETEA-LU, Congress was aware of the agency's past work on advanced side glazing and of our ejection mitigation research program. Congress was aware that side curtain air bags were showing strong potential as an ejection mitigation countermeasure and that we had redirected research and rulemaking efforts from advanced side glazing to developing performance-based test procedures for an ejection mitigation standard.

19

19

“Ejection Mitigation Using Advanced Glazing, Final Report,” NHTSA, August 2001, Docket 1782-22. See also, NHTSA's termination of an advance notice of proposed rulemaking on advanced glazing (67 FR 41365, June 18, 2002),

infra.

In addition, in the legislative history on section 10301, section 7251 of the Senate bill which the Conference committee adopted (Conference Report of the Committee of Conference on H.R. 3, Report 109-203, 109th Congress, 1st Session) directed the Secretary to include consideration of “advanced

side

glazing,

side

air curtains, and

side

impact air bags” (emphases added) in establishing the standard. We believe that Congress wanted us to take into account the knowledge gained from our past work on side ejections in formulating this standard, which we have, building on our knowledge gained from the advanced side glazing and rollover crashworthiness programs.

It would take a longer time than the timeframe allowed by SAFETEA-LU to address fatal ejections through the back light and roof portals. In contrast to the side window research program, which started in the early 1990s, the agency had no research and development foundation upon which requirements for the back light and roof portal could be based. Much is unknown regarding a test procedure, effectiveness of current designs, method of anchoring advanced glazing to the backlight frame and roof portal, and possible other countermeasures and their costs. The agency believed that Congress intended us to build on the knowledge already attained and issue this final rule addressing side window ejections, which account for 62 percent of all fatal occupant ejections in all crashes, as quickly as possible, rather than delay this final rule to venture into areas that account for 8.7 percent of those fatal ejections.

In sum, we developed this final rule to meet the criteria of section 10301 of SAFETEA-LU and the Vehicle Safety Act, making sure that it is a performance standard that reduces complete and partial ejections from outboard seating positions and that it is reasonable, practicable, and appropriate, that it meets the need for safety and is stated in objective terms. Further, ensuring that the final rule is consistent with Executive Order 12866, we have adopted requirements that not only maximize the benefits of a cost-effective approach to ejection mitigation, but do so with an approach that saves over 370 lives. This final rule wholly implements the instructions of our statutory and administrative directives.

IV. Summary of the NPRM

NHTSA issued a proposal for a new FMVSS No. 226 and proposed the standard apply to passenger cars, multipurpose passenger vehicles, trucks and buses with a GVWR of 4,536 kg or less. We proposed that the side windows next to the first three rows of seats be subject to performance requirements requiring the vehicle to have an ejection mitigation countermeasure that would prevent an 18 kg (40 lb) headform from moving more than 100 mm (4 inches) beyond the zero displacement plane of each window when the window is impacted. Each side window would be impacted at up to four locations around its perimeter at two energy levels and time intervals following deployment. The first impact was proposed to be at 24 km/h, 1.5 seconds after deployment of the ejection mitigation side curtain air bag, assuming there was one present (“24 km/h-1.5 second test”), and the second impact was proposed to be at 16 km/h, at 6 seconds after deployment (“16 km/h-6 second test”). The NPRM proposed to allow windows of advanced glazing to be in position during the test, but pre-broken, using a prescribed method, to reproduce the state of glazing in an actual rollover crash.

The NPRM discussed proposals for: (a) The impactor dimensions and mass; (b) the displacement limit; (c) impactor speed and time of impact; and (d) target locations. We also discussed: (e) glazing issues; (f) test procedure tolerances; (g) test device characteristics; and other issues, such as a requirement for a readiness indicator.

The NPRM did not specifically require a rollover sensor to deploy the curtains or attributes that the sensor must meet; manufacturers currently provide sensors with their ejection mitigation curtains and NHTSA believed they will continue to provide a sensor enabling deployment regardless of an express requirement to do so. With regard to applicability, the agency tentatively decided in the NPRM not to exclude convertibles but requested comments on this issue and on the applicability of the standard to other

types of vehicles,

e.g.,

police vehicles with security partitions.

Except for limited line and multistage manufacturers, the proposed lead time was the first September 1 three years from the date of publication of a final rule. The requirements were proposed to be phased in over a four-year period, with 20 percent of each manufacturer's vehicles manufactured during the first production year required to meet the standard, 40 percent manufactured during the second year required to meet the standard, 75 percent of vehicles manufactured during the third year required to meet the standard, and all vehicles (without use of advanced credits) manufactured on or after the fourth year required to meet the standard. It was proposed that limited line and multistage manufacturers would not have to achieve full compliance until one year after the phase-in is completed.

Accompanying the NPRM was a Preliminary Regulatory Impact Analysis (PRIA) analyzing the potential impacts of the proposed ejection mitigation requirements, and a technical analysis prepared by the agency that presented a detailed analysis of engineering studies, and other information supporting the NPRM (“Technical Analysis in Support of a Notice of Proposed Rulemaking Ejection Mitigation”). Both documents were placed in the docket for the NPRM (Docket No. NHTSA-2009-0183).

V. Summary of the Comments

NHTSA received 35 comments on the NPRM. Comments were received from motor vehicle manufacturers through their associations and individually, from air bag and glazing equipment suppliers (also through their associations and individually), and from consumer and insurance groups, and individuals.

The Alliance of Automobile Manufacturers (Alliance)

20

stated that it was generally supportive of many aspects of the NPRM, such as the use of a linear headform impactor for evaluating rollover deployed side curtains and the decision not to specify a protocol for testing rollover sensors. However, the commenter disagreed with the proposed performance requirements, believing that they are overly stringent and may unnecessarily force the development of air bag systems that could have adverse unintended consequences. The commenter stated that seat belt use is the most effective countermeasure for ejection mitigation. The Alliance stated its belief that there should be only one test at 16 km/h and at 3.4 seconds, with an excursion limit of 150 mm measured from a plane tangent to the exterior of the vehicle. The Alliance also stated its belief that the standard should not apply to convertibles and to vehicles with partitions, for practicability reasons. Further, the commenter asked for an additional year of lead time, and that vehicles with a GVWR greater than 2,722 kg (6,000 lb) should have a compliance date that is one year after the 100 percent phase-in date for completed vehicles with a GVWR of 2,722 kg or less. The Alliance also had technical comments on specific aspects of the test procedure.

20

The Alliance member companies are BMW Group, Chrysler Group, Ford Motor Company, General Motors, Jaguar Land Rover, Mazda, Mercedes-Benz USA, Mitsubishi Motors, Porsche, Toyota, and Volkswagen (VW).

The Alliance's member companies commenting on the NPRM reiterated the views of the Alliance, with some expounding on the following matters of particular interest to them. General Motors (GM) stated that the Alliance's suggested compliance date and phase-in schedule could be met assuming that NHTSA adopts the modifications of the test procedure identified by the Alliance and excludes convertibles and vehicles with partitions. Ford commented that side glazing retention in real-world rollover crashes is random and unpredictable and expressed the belief that FMVSS No. 226 should be focused on rollover-activated side curtain technology because these devices are designed to deploy regardless of side glazing status in a rollover (

e.g.,

retained, up, down or partially open) or construction of the glazing. Mercedes raised concerns about the difficulties larger vans such as the Sprinter would have in meeting the requirements and asked for additional lead time for vehicles over 8,500 lb GVWR. Porsche discussed the long lifecycles for its sports cars and asked that manufacturers be allowed to use credits earned for early compliance through the end of the 100 percent phase-in year. Various manufacturers expressed technical views or had questions about specific aspects of the test procedure.

The Association of International Automobile Manufacturers Technical Affairs Committee

21

(AIAM) stated that it “supports the agency's basic approach in the proposed ejection mitigation standard” but is “concerned that there may be unintended consequences if test criteria establish unnecessary high levels of energy for the test impactor.” AIAM said that high test impact speeds could require the use of stiffer side curtain air bags or advanced glazing of increased rigidity to meet the specified displacement limit. “Such consequences may increase the risk of head/neck injuries.” AIAM urged the agency to consider whether the impactor energy specifications may be reduced to a level equivalent to 180 Nm (corresponding to a 16 km/h test). The commenter believed that convertibles should be excluded from the standard for practicability reasons and also suggested that certain classes of vehicle could be excluded from the high speed requirement due to vehicle characteristics that can dissipate the energy of occupants in rollovers, such as vehicles having high “belt-lines” (

e.g.,

sports cars that seat the occupants low relative to the window openings). AIAM asked for an additional year of lead time prior to the start of the phase-in period and asked that advanced credits be allowed to meet the 100 percent stage of the phase-in. AIAM also commented on specific aspects of the test procedure and supported GM's suggested procedure for measuring impactor displacement from a plane tangent to the vehicle's exterior.

21

AIAM Technical Affairs Committee members are American Honda Motor Company (Honda), American Suzuki Motor Corp., Aston Martin Lagonda of North America, Ferrari North America, Hyundai Motor America (Hyundai), Isuzu Motor America, Kia Motors America, Maserati North America, Nissan North America, Peugeot Motors of America, Subaru of America, ADVICS North America, Delphi Corporation, Denso International America, and Robert Bosch Corporation.

AIAM members commenting on the NPRM generally reiterated AIAM's views, with some separately raising issues of individual concern. Honda stated its belief that with an energy level of 200 joules (J), occupant ejection mitigation can be balanced with occupant protection without unintended adverse consequences to occupant protection. The commenter suggested the test procedure consist of one test at 17 km/h with a 3.0 second time delay. Honda agreed with the proposed 100 mm displacement limit, but suggested that displacement along a line normal to the actual window at the center of each target impact point should not exceed 100 mm. Nissan suggested the agency adopt a 20 km/h test instead of the proposed 24 km/h test. In their individual comments, various vehicle manufacturers asked for clarification of or changes to particular aspects of the proposed test procedure.

Organizations representing specialized manufacturers commented on the NPRM. Vehicle Services Consulting, Inc. (VSC)

22

supported the

NPRM, but asked that convertibles be excluded from the standard. VSC also asked for clarification of regulatory text applying to small volume manufacturers. The National Truck Equipment Association (NTEA)

23

requested that NHTSA exclude from the ejection mitigation standard work trucks built in two or more stages, particularly those with partitions, and vehicles with alterations to the floor height.

22

VSC states: “Vehicle Services Consulting, Inc. assists numerous small volume vehicle manufacturers with US certification-related matters.”

23

NTEA describes itself as a “trade association representing distributors and manufacturers of multi-stage produced, work related trucks, truck bodies and equipment.”

Air bag supplier groups commented in favor of the NPRM. Takata Corporation, a manufacturer of air bags and other motor vehicle equipment, stated that it supports NHTSA's goal to establish a new FMVSS to reduce the partial and complete ejection of occupants in rollover crashes.

24

However, Takata expressed concern about the effectiveness of applying the ejection mitigation standard to convertibles at this time. TRW, a manufacturer of vehicle safety systems, and the Automotive Occupant Restraints Council (AORC)

25

supported the agency's proposal in general, but suggested that all windows should be tested down or removed regardless of whether the glazing is laminated since motorists occasionally drive with their windows open. TRW and AORC also expressed concern about applying the ejection mitigation requirements to convertibles. Each of these commenters had detailed feedback on and suggestions for improving the proposed test procedures.

24

Takata also submitted information to NHTSA's ejection mitigation research docket (NHTSA-2006-26467) indicating that meeting the proposed performance requirements in non-convertibles would be practicable.

25

AORC describes itself as a non-profit organization whose mission is to promote automotive safety through education and technology. Its membership consists of safety system manufacturers and their suppliers.

Glazing manufacturers and suppliers commenting on the NPRM generally supported the objectives and overall structure of the proposed standard, but a number had the view that the agency fell short of the congressional mandate of section 10301 of SAFETEA-LU, in that roof glazing and backlight areas were not being regulated by the new standard. Many of these groups also desired a reduction in the performance limit, some by 50 percent (i.e., a displacement limit of 50 mm). Many of the groups commented that all windows should be tested in the up (closed) position and several objected to the pre-test breaking procedure for glazing as being excessive and suggested changes to it, such as eliminating the specification to pre-break the interior surface of the glazing. Many of these glazing supplier groups requested a shorter lead time and phase-in period.

Consumer groups Public Citizen (PC) and Advocates for Highway and Auto Safety (Advocates) commented on the NPRM. PC stated that the NPRM is flawed because it does not address occupant ejections through the roof and because the cost-benefit analysis is “devised with the same misleading approach to determining a target population that NHTSA has used in other rollover rulemakings.” PC suggested NHTSA establish a performance requirement that would encourage the dual use of laminated glazing and side curtain air bags, but stated that NHTSA should not permit laminated glazing in vehicles not equipped with side curtain air bags. PC suggested that the phase-in schedule should begin and end one model year earlier than proposed. The commenter also was critical that “the agency has not taken a comprehensive, whole vehicle approach to reducing fatalities in rollover crashes.”

Advocates stated its belief that NHTSA interpreted SAFETEA-LU too narrowly by addressing occupant ejection only through side windows and not through side doors, tailgates, windshields, backlights, or sun roofs. Advocates suggested that roofs can be strengthened and occupant ejection reduced through the use of advanced glazing and that NHTSA should promote pre-crash automated window closure to ensure that vehicles with advanced glazing would be in the windows-up position. Advocates supported “mandatory anti-ejection countermeasures to be applied at all designated seating positions, not just for outboard occupants in the first, second, and third rows,” including all occupant positions in the rear seats of 15-passenger vans. Advocates believed that the 100 mm proposed displacement limit should be 50 mm and that areas outside of the target zones should be tested. The commenter was concerned about the proposed time intervals for the impactor tests

26

and desired performance requirements for rollover air curtain sensors. The commenter believed that manufacturers would only need a two-year lead time and a three-year phase-in period to meet the proposed requirements.

26

Advocates was concerned that “no sustained inflation is tested between the 1.5 and 6 second tests, when excursion could exceed the 4 inch maximum required by the proposed standard.”

The Insurance Institute for Highway Safety (IIHS) said it supported the NPRM because the commenter believed that the rulemaking is likely to result in all passenger vehicles being equipped with side curtain air bags that deploy in rollover crashes. However, IIHS stated that the proposed 100 mm excursion limit may be overly restrictive. IIHS also stated that the agency should provide an incentive to manufacturers to equip vehicles with laminated side glazing.

Several individuals responded in general support of the NPRM and with several suggestions. National Forensic Engineers, Inc. supported the use of laminated glazing in side windows to supplement side curtain air bags. Stephen Batzer and Mariusz Ziejewski, and Byron Bloch, stated that the standard should apply to vehicles above 4,536 kg, to daylight openings adjacent to every designated seating position and to the windshield, sunroof and backlight, and supported the use of laminated glazing. Batzer and Ziejewski believed that a 10 mph impact would be sufficient. Bloch urged the agency to evaluate ejection mitigation through a dynamic full vehicle rollover test.

VI. How the Final Rule Differs From the NPRM

The more important changes from the NPRM are listed in this section and explained in detail later in this preamble. Changes more minor in significance (

e.g.,

changes that clarify test procedures) are not listed below but are discussed in the appropriate sections of this preamble.

i. The high speed impact test, performed at 1.5 seconds after ejection mitigation side curtain air bag deployment, will have an impact velocity of 20 km/h instead of 24 km/h. After evaluating the comments to the NPRM, the agency reanalyzed the test data upon which the impact speed proposed in the NPRM was based, analyzed the new testing conducted since the NPRM, and considered all submitted information. Based on this analysis, we agree to decrease the impact test speed to 20 km/h, as suggested by Nissan in its comment, which results in 278 joules (J) of impact energy. This energy value is well supported and more representative of the energy the ejection countermeasure will typically be exposed to in the field, particularly in rollovers. All target locations in each window opening will be subject to the high speed test, performed at 1.5 seconds after ejection mitigation side curtain air bag deployment (“20 km/h-1.5 second test”), and to the low speed 16 km/h test

performed 6 seconds after deployment (“16 km/h-6 second test”).

ii. If necessary, the headform and targets will be rotated by 90 degrees to a horizontal orientation if this results in more impact locations than the vertical orientation (to a maximum of four target locations). For long narrow windows, popular in many late model vehicles, very limited target coverage of the opening is achieved if the target is kept in the vertical orientation. It did not make sense to exclude windows from being subject to full ejection mitigation protection simply because the headform could not fit when oriented vertically.

iii. The standard does not permit the use of movable advanced glazing as the sole means of meeting the displacement limit of the standard. In addition, the 16 km/h-6 second test must be performed without the use of advanced glazing for movable windows. Field data indicates that even when initially up, movable advanced glazing may be destroyed and made ineffective as a countermeasure beyond the initial phase of a rollover. Therefore, the final rule will require that if a vehicle has movable advanced glazing as part of the ejection countermeasure, the 16 km/h-6 second test will be performed with the glazing retracted or removed from the window opening. This approach will assure a reasonable level of safety when side glazing is rolled down or when the severity of the rollover damages or destroys the effectiveness of the glazing, and still encourages the use of advanced glazing as a countermeasure to supplement the vehicle's performance in meeting the 20 km/h-1.5 second test.

iv. The window opening for cargo areas behind the 1st and 2nd row will be impacted. If there is a side window opening in a cargo area behind the 1st row of a single row vehicle or behind the 2nd row of a two-row vehicle, this final rule will extend coverage to those cargo areas behind the 1st and 2nd rows of vehicles. The area of side window openings in a cargo area will be bounded by a transverse plane 1,400 mm behind the seating reference point (SgRP) of the rearmost seat in the 1st row of a single row vehicle or behind the SgRP of the rearmost seat in the 2nd row of a two-row vehicle. Field data found that cargo area ejections behind a 2nd row were similar in frequency to 3rd row ejections. Such cargo area coverage is cost effective and is not any more challenging than 3rd row coverage.

v. Minor changes were made in the definition of and procedure for determining the window opening. The final rule increases the lateral distance defining the window opening from 50 to 100 mm. We have examined interior trim components, such as panels covering the vehicle pillars and found that relevant surfaces can be more than 50 mm from the inside of the window glazing and that these trim components can be difficult to remove.

vi. The final rule slightly modifies the glazing pre-breaking procedure by using a 75 mm offset pattern. (We disagree with the comments that stated the pre-breaking procedure should be deleted or should be restricted to four points on the glazing. We believe the pre-breaking procedure is necessary to recreate the damage that will likely occur in the field.)

vii. Convertibles are excluded from this standard. Also excluded are law enforcement vehicles, correctional institution vehicles, taxis and limousines with a fixed security partition separating the 1st and 2nd or 2nd and 3rd rows, if the vehicle is a multistage or altered vehicle.

viii. The final rule has a 2-year lead time period, with 25 percent of each manufacturer's vehicles manufactured during the first production year required to meet the standard, 50 percent manufactured during the second year required to meet the standard, 75 percent of vehicles manufactured during the third year required to meet the standard, and 100 percent of vehicles manufactured on or after the fourth year required to meet the standard. The final rule allows manufacturers to use advanced credits to meet the phase-in percentages, including advanced credits in the last year (100 percent year) of the phase-in schedule.

ix. Characteristics of the guided linear impactor with the 18 kg headform and the associated propulsion mechanism were refined to assure sufficient repeatability and reproducibility of the test. The impactor used in research tests was originally constructed in the advanced glazing program of the 1990s. We have reduced the maximum allowable dynamic coefficient of friction of the test device by a factor of 5, from 1.29 (old impactor) to 0.25 (new impactor). The device has been made less flexible along its shaft and thus better able to maintain its orientation as it interacts with ejection countermeasures.

VII. Foundations for This Rulemaking

This section discusses knowledge and insights we gained from past research on ejection mitigation safety systems which underlie many of the decisions we made in forming this final rule.

a. Advanced Glazing

In formulating this final rule, NHTSA considered various ejection mitigation systems in accordance with section 10301 of SAFETEA-LU. One of the considered systems was advanced side glazing. In the 1990s, NHTSA closely studied advanced glazing as a potential ejection mitigation countermeasure

27

but terminated an advance notice of proposed rulemaking on advanced glazing in 2002 (67 FR 41365, June 18, 2002). The termination was based on our observation that advanced glazing produced higher neck shear loads and neck moments than impacts into tempered

28

side glazing. In addition, the estimated incremental cost for installing ejection mitigation glazing in front side windows ranged from over $800 million to over $1.3 billion, based on light vehicle annual sales of 17 million units in the 2005-2006 timeframe. Also, because side curtain air bags were showing potential as an ejection mitigation countermeasure, NHTSA decided to redirect its research and rulemaking efforts toward developing performance-based test procedures for an ejection mitigation standard.

29

27

Ejection mitigation glazing systems have a multi-layer construction with three primary layers. There is usually a plastic laminate bonded between two pieces of glass.

28

Tempered glass is made from a single piece of specially treated sheet, plate, or float glass possessing mechanical strength substantially higher than annealed glass. When broken at any point, the entire piece breaks into small pieces that have relatively dull edges as compared to those of broken pieces of annealed glass. (

See

FMVSS No. 205, “Glazing Materials,” incorporating by reference standard ANSI/SAE Z26.1-1996.)

29

“Ejection Mitigation Using Advanced Glazing, Final Report,” NHTSA, August 2001, Docket No. NHTSA-1996-1782-22.

Elements from the advanced glazing program underlie a substantial part of today's final rule. The headform and the test procedure were originally developed in the advanced glazing research program.

Further, as with all of the FMVSSs, we drafted this final rule to be performance-oriented, to provide manufacturers wide flexibility and opportunity for design innovation in developing countermeasures that could be used for ejection mitigation. We anticipate that manufacturers will install ejection mitigation side curtain air bags in response to this rulemaking, taking advantage of the side impact curtains already in vehicles. Nonetheless, this final rule provides a role for advanced glazing as a complement to ejection mitigation curtain systems.

NHTSA tested several vehicles' ejection mitigation side curtain air bags both with and without advanced glazing to the 18 kg impactor performance test adopted by this final rule. In the tests, the glazing was pre-broken to simulate the likely condition of the glazing in a rollover. Tests of vehicles with advanced glazing resulted in a 51 mm average reduction in impactor displacement across target locations.

30

That is, optimum (least) displacement of the headform resulted from use of both an ejection mitigation window curtain and advanced glazing. To encourage manufacturers to enhance ejection mitigation curtains with advanced glazing, the final rule allows windows of advanced glazing to be in-position for the 20 km/h-1.5 second test, although pre-broken to reproduce the state of glazing in an actual rollover crash. This approach encourages advanced glazing as a countermeasure to supplement the vehicle's performance in meeting the 20 km/h-1.5 second test.

31

30

See the technical analysis prepared by the agency in support of the NPRM, placed in the docket for the NPRM (NHTSA-2009-0183-007). “Technical Analysis in Support of a Notice of Proposed Rulemaking for Ejection Mitigation.” Among other matters, the report discusses the results of NHTSA's impactor testing of OEM and prototype side window ejection mitigation systems.

31

Yet, after reviewing comments to the NPRM and other information, we have decided not to permit movable glazing to supplement the primary ejection mitigation system in the 16 km/h-6 second test. This is because field data indicate that even when initially up, movable advanced glazing may be destroyed and rendered ineffective as an effective countermeasure beyond the initial phase of a rollover. In addition, 30 percent of occupants are ejected through windows that are partially or fully open prior to the crash.

b. Full Window Opening Coverage Is Key

We considered the findings of several NHTSA research programs on rollover crashworthiness protection in developing this final rule.

A cornerstone program started with the development of a dynamic rollover fixture (DRF) that could be used to produce full-dummy ejection kinematics in an open window condition, where the peak roll rate ranged between 330 to 360 degrees/second. The DRF was used to assess the potential effectiveness of ejection mitigation countermeasures in a rollover.

32

These countermeasures included several designs of inflatable curtain air bags, advanced glazing, and combinations of curtains and advanced glazing. The results of the assessment showed that not all ejection mitigation air bag curtains work the same way. We found that full window opening coverage was key to the effectiveness of the curtain in preventing ejection.

32

NHTSA developed the DRF to produce full-dummy ejection kinematics in a less costly manner than full-scale testing. The DRF models a lateral rollover crash of approximately one vehicle revolution. The DRF rotates approximately one revolution and comes to rest through the application of a pneumatic braking system on one end of the pivot axle. It does not simulate lateral vehicle accelerations often encountered in a rollover crash prior to initiation of the rollover event. The DRF has a test buck fabricated from a Chevrolet CK pickup cab. The cab is longitudinally divided down the center from the firewall to the B-pillar. The left (driver) side is rigidly attached to the test platform. The Chevrolet CK was chosen so that the advanced glazing systems developed in the previous ejection mitigation research could be evaluated in this program. A seat back and cushion were made from Teflon material, to minimize the shear forces on the dummy buttocks for more desired loading on the window area by the dummy's head and upper torso.

1. Tests with 50th Percentile Adult Male and 5th Percentile Adult Female Test Dummies

In the first research program, experimental roof rail-mounted inflatable devices developed by Simula Automotive Safety Devices (Simula) and by TRW were evaluated on the DRF, along with an advanced side glazing system.

33

In the tests, unrestrained 50th percentile male and 5th percentile female Hybrid III dummies, instrumented with 6 axis upper neck load cells and tri-axial accelerometers in the head, were separately placed in the buck.

34

The DRF rotation resulted in a centripetal acceleration of the dummy that caused the dummy to move outwards towards the side door/window. In baseline tests of the unrestrained dummies in the DRF with an open side window and no countermeasure, the dummies were fully ejected. The ability of the countermeasure to restrain the dummies could then be assessed and compared to that baseline test.

33

“Status of NHTSA's Ejection Mitigation Research Program,” Willke

et al.,

18th International Technical Conference on the Enhanced Safety of Vehicles, paper number 342, June 2003.

34

Two dummy positions were used. The first was behind the steering wheel. The second position was more inward, toward the pivot axle, which generated higher contact velocities. Film analysis was used to measure the dummy's relative head and shoulder contact velocity with the side window plane from these two seating positions. (For the final rule, we digitized the films and reanalyzed the impact speeds using data from state-of-the-art software. The resulting impacts speeds were lower than those reported in the NPRM. The analysis will be discussed later in this document.) From the first position behind the steering wheel, the shoulder impact speeds were 7.0 km/h (4.3 mph) for the 5th percentile female dummy and 9.0 km/h (5.6 mph) for the 50th male. From the second (inboard) position, the velocities were 15.5 km/h (9.6 mph) for the 5th female dummy and 15.8 km/h (9.8 mph) for the 50th male.

In the tests of the experimental inflatable devices, the air bags were pre-deployed and their inflation pressure was maintained throughout the test by the use of an air reservoir tank mounted on the platform.

35

In the tests, the dummy's upper body loaded the inflatable device, which limited the dummy's vertical movement toward the roof and caused the pelvis to load the side door throughout the roll, rather than to ride up the door. The inflatable devices contained the torso, head, and neck of the dummy, so complete ejection did not occur. However, both devices did allow partial ejection of the dummy's shoulder and arm below the bags, between the inflatable devices and the vehicle door.

35

Since these were experimental systems, they were not deployed through pyrotechnic or in-vehicle compressed gas, as might be the case with production designs. The air pressure supplied by the laboratory reservoir kept the systems fully inflated over the test period.

In the test of the advanced side glazing (laminated with door/window frame modifications around the entire periphery to provide edge capture), the glazing contained the dummies entirely inside the test buck. The glazing was not pre-broken before the testing. There was some flexing of the window frame when the dummies loaded the glazing, and the 50th percentile male dummy's shoulder shattered the glass when the dummy was located behind the steering wheel.

In the test of the combined systems, the dummies remained entirely inside the buck. Although the dummy's shoulder and arm escaped under the inflatable devices, the advanced glazing prevented the partial ejection seen in tests of the inflatable devices alone.

In these tests, the ejection mitigation systems did not show a high potential for producing head and neck injury. However, head and neck loading were higher than the open window condition. The highest load with respect to the Injury Assessment Reference Values (IARVs) was 82 percent for the neck compression for the 5th percentile female tested with the Simula/laminate combination. The highest injury response for the 50th percentile male dummy was 59 percent for the neck compression with the TRW system alone. All HIC

36

36

responses were extremely low and ranged from 8 to 90, with the maximum occurring in an open window test. Lateral shear and bending moment of the neck were also measured, although there are no established IARVs. The maximum lateral neck shear loads were 950 N (50th percentile male tested with TRW

system) and 1020 N (5th percentile female tested with laminate only).

36

HIC

36

is the Head Injury Criterion computed over a 36 msec duration. HIC

36

= 1,000 represents an onset of concussion and brain injury.

2. Tests With 6-Year-Old Child Test Dummy Showed a Risk of Ejection Through Openings Not Fully Covered

The second research program involved a series of tests on the DRF using an unrestrained Hybrid III 6-year-old dummy. In previous tests with the 50th percentile adult male and 5th percentile adult female dummies, a gap formed between the inflatable devices and the window sill (bottom of the window opening), which allowed partial ejection of those adult dummies. The second program investigated whether the gap allowed ejection of the 6-year-old child dummy.

37

37

“NHTSA's Crashworthiness Rollover Research Program,” Summers, S.,

et al.,

19th International Technical Conference on the Enhanced Safety of Vehicles, paper number 05-0279, 2005.

In baseline testing with an open side window without activation of an ejection mitigation countermeasure, the child dummy was fully ejected. In tests of the two inflatable systems tested in the first program (at the time of the second research program, the inflatable device formerly developed by Simula was then developed by Zodiac Automotive US (Zodiac)), the inflatable devices prevented full ejection of the 6-year-old child dummy in upright-seated positions (no booster seat was used). However, dummy loading on the systems produced gaps that did allow an arm and/or hand to pass through in some tests. Moreover, in a series of tests with the dummy lying in a prone position (the dummy was placed on its back at the height of the bottom of the window opening), representing a near worst-case ejection condition, the dummy was completely ejected at positions near the bottom of the inflatable devices (above the sill) with the TRW curtain, while the Zodiac system contained the dummy inside the test buck in all testing. Adding pre-broken advanced glazing with the TRW system managed to contain the dummy inside the test buck in all tests.

38

38

Id.

3. Differences in Design Between the Two Inflatable Systems

The two prototype inflatable devices tested had fundamentally different designs. The Zodiac/Simula prototype system used an inflatable tubular structure (ITS)

39

tethered near the base of the A and B-pillars that deployed a woven material over the window opening. (The Zodiac system differed from the originally-tested Simula design in that it had more window coverage. This was achieved by placing the ITS tether locations lower on the pillars and adding additional woven material.) The TRW prototype was more akin to a typical air bag curtain and was fixed to the A- and B-pillar at its end points and along the roof rail, but not tethered. The ITS differed from conventional air bags in that it was not vented.

39

ITS systems were originally introduced by BMW as a side impact countermeasure.

We believe that the better performance of the Zodiac prototype system compared to that of TRW, in the DRF testing described above and in impactor test results provided later in this preamble, was due to the greater window coverage by the Zodiac prototype along the entire sill and A-pillar.

4. Insights

The DRF research provided the following insights into ejection mitigation curtains:

• Inflatable devices prevented ejection of test dummies in simulated rollover tests, but design differences accounted for differences in performance;

• Gaps in the inflatable device's coverage of the window opening at the sill and A-pillar allowed partial ejection of adult dummies and full ejection of a 6-year-old child dummy;

• Adding pre-broken advanced glazing to an air bag system enhanced the ability of the system to contain the dummy; and,

• To optimize ejection mitigation potential, a performance test should ensure that the countermeasure has full coverage of the window opening.

c. Comparable Performance in Simulated Rollovers and Component-Level Impact Tests

Because full-vehicle rollover crash tests can have an undesired amount of variability in vehicle and occupant kinematics, in the advanced glazing program NHTSA developed a component-level impact test for assessing excursion and the risk of ejection. We use the component-level test in this final rule for ejection mitigation.

The test involves use of a guided linear impactor designed to replicate the loading of a 50th percentile male occupant's head and shoulder during ejection situations. The impactor

40

is described later in this preamble. There are many possible ways of delivering the impactor to the target location on the ejection mitigation countermeasure. The ejection mitigation test device

41

used by the agency in the advanced glazing program and for the research used to develop the NPRM (“old impactor”) has a propulsion mechanism

42

with a pneumatic piston that pushes the shaft component of the impactor. The old impactor shaft slides along a plastic (polyethylene) bearing. The impactor has an 18 kg mass.

40

The “ejection impactor” is the moving mass that strikes the ejection mitigation countermeasure. It consists of an ejection headform attached to a shaft.

41

The ejection mitigation test device consists of an ejection impactor and ejection propulsion mechanism.

42

The “ejection propulsion mechanism” is the component that propels the ejection impactor and constrains it to move along its axis or shaft.

The component-level test identified four impact locations to evaluate a countermeasure's window coverage and retention capability. Two of the positions were located at the extreme corners of the window/frame and were located such that a 25 mm gap existed between the outermost perimeter of the headform and window frame. A third position was near the transition between the upper window frame edge and A-pillar edge. The fourth position was at the longitudinal midpoint between the third position and the position at the upper extreme corner of the window/door frame, such that the lowest edge of the headform was 25 mm above the surface of the door at the bottom of the window opening.

At each impact location, different impact speeds and different time delays between air bag deployment and impact were used. To simulate ejection early in a rollover event and in a side impact, the air bags were impacted 1.5 seconds after air bag deployment, at 20 and 24 km/h. To simulate ejection late in a rollover event, the air bags were impacted after a delay of 6 seconds at an impact speed of 16 km/h.

Findings

The two inflatable systems tested in the above-described research programs (the inflatable devices developed by Zodiac and by TRW) were installed on a Chevrolet CK pickup cab and subjected to the component-level impact test. The air bag systems were evaluated for allowable excursion (impactor displacement) beyond the side window plane. The tests also assessed the degree to which the component-level test was able to replicate the findings of the DRF tests.

The component-level tests mimicked the DRF tests by revealing the same deficiencies in the side curtain air bags that were highlighted in the dynamic test. On the other hand, the Zodiac

system

43

did not allow the impactor to go beyond the plane of the window in the 16 km/h and 20 km/h tests. The air bag allowed only 12 and 19 mm of excursion beyond the window plane in the 24 km/h tests.

43

Testing was restricted to the extreme corners of the window due to limited availability of this system.

In the 24 km/h tests of the TRW system, the curtain was not able to stop the impactor before the limits of travel were reached (about 180 mm beyond the plane for the vehicle window for that test setup) at the position at the extreme forward corner of the window sill. This is the position at which the TRW prototype system allowed excessive excursion of the test dummies in the DRF dynamic tests. In the DRF tests, the 6-year-old dummy was completely ejected through that window area even when the prone dummy was aimed at the position at the other extreme corner of the window. In other tests, the TRW prototype system was able to stop the impactor before the impactor reached its physical stops.

d. Advantages of a Component Test Over a Full Vehicle Dynamic Test

NHTSA determined that the component test not only distinguishes between acceptable and unacceptable performance in side curtain air bags, but has advantages over a full vehicle dynamic test. The acceptable (or poor) performance in the laboratory test correlated to the acceptable (or poor) performance in the dynamic test. The component test was able to reveal deficiencies in window coverage of ejection mitigation curtains that resulted in partial or full ejections in dynamic conditions. Incorporating the component test into an ejection mitigation standard ensures that ejection mitigation countermeasures provide sufficient coverage of the window opening for as long in the crash event as the risk of ejection exists, which is a key component contributing to the efficacy of the system.

As noted earlier, rollover crash tests can have an undesirable amount of variability in vehicle and occupant kinematics. In contrast, the repeatability of the component test has been shown to be good.

44

Moreover, there are many types of rollover crashes, and within each crash type the vehicle speed and other parameters can vary widely. A curb trip can be a very fast event with a relatively high lateral acceleration. Soil and gravel trips have lower lateral accelerations than a curb trip and lower initial roll rates. Fall-over rollovers are the longest duration events, and it can be difficult to distinguish between rollover and non-rollover events. Viano and Parenteau

45

correlated eight different tests to six rollover definitions from NASS-CDS.

46

Their analysis indicated that the types of rollovers occurring in the real-world varied significantly. Soil trip rollovers accounted for more than 47 percent of the rollovers in the field, while less than 1 percent of real-world rollovers were represented by the FMVSS No. 208 Dolly test (“208 Dolly test”).

44

“NHTSA's Crashworthiness Rollover Research Program,”

supra.

45

Viano D, Parenteau C. Rollover Crash Sensing and Safety Overview. SAE 2004-01-0342.

46

“Technical Analysis in Support of a Notice of Proposed Rulemaking for Ejection Mitigation,”

supra.

Occupant kinematics will also vary with these crash types, resulting in different probabilities of occupant contact on certain areas of the side window opening with differing impact energies. A single full vehicle rollover test could narrowly focus on only certain types of rollover crashes occurring in the field.

47

Assuming it is at all possible to comprehensively assess ejection mitigation countermeasures through full vehicle dynamic testing, multiple crash scenarios would have to be involved.

47

The agency has in the past performed dolly type dynamic testing. The agency has not performed enough repeat tests of the same vehicles to draw any conclusions about the repeatability of these tests to determine occupant containment. However, regardless of the level of repeatability of dummy kinematics, it still only represents a part of the kinematics that would occur in the field.

Such a suite of tests imposes test burdens and costs that could be avoided by a component test, such as that adopted today. We also note that a comprehensive suite of full-vehicle dynamic tests would involve many more years of research, which would delay this rulemaking action and the implementation of life-saving curtain air bag technologies. Such a delay is unwarranted and undesirable since the component test will be an effective means of determining the acceptability of ejection countermeasures.

VIII. Availability of Side Curtain Air Bags

The availability of vehicles that offer inflatable side curtains that deploy in a rollover has increased since they first became available in 2002. In the middle of the 2002 model year (MY), Ford introduced the first generation of side curtain air bags that were designed to deploy in the event of a rollover crash. The rollover air bag curtain system, marketed as a “Safety Canopy,” was introduced as an option on the Ford Explorer and Mercury Mountaineer.

48

For the 2007 MY, rollover sensors were available on approximately 95 models, with 75 of these models being sport utility vehicles. The system was standard equipment on 62 vehicles (65 percent) and optional on 33 vehicles (35 percent).

48

http://media.ford.com/article_display.cfm?article_id=6447

(Last accessed October 8, 2010.)

Annually, as part of NHTSA's New Car Assessment Program (NCAP), the agency sends a questionnaire to manufacturers requesting information about the availability of certain safety systems on their vehicles.

49

Since 2008, NHTSA has asked manufacturers for voluntary responses regarding whether their available side impact curtains will deploy in a rollover crash. The voluntary responses were in the affirmative for 39 percent of MY 2008 make models and for 43 percent of MY 2010 make models.

49

The total number of make/models represented in the survey is about 500. Slight model variations are represented as different models and corporate twins are not combined.

IX. Existing Curtains

Aside from the presence of a rollover sensor, there are two important design differences between air bag curtains designed for rollover ejection mitigation and air bag curtains designed only for side impact protection. The first difference is longer inflation duration. Rollover crashes with multiple full vehicle rotations can last many seconds. Ford has stated that its Safety Canopy stays inflated for 6 seconds,

50

while GM stated that its side curtain air bags designed for rollover protection maintain 80 percent inflation pressure for 5 seconds.

51

Honda stated that the side curtains on the 2005 and later Honda Odyssey stay fully inflated for 3 seconds.

52

In contrast, side impact air bag curtains designed for occupant protection in side crashes, generally stay inflated for less than 0.1 seconds.

50

Ibid.

51

“Who Benefits From Side and Head Airbags?” (

http://www.edmunds.com/ownership/safety/articles/105563/article.html

). (Last accessed October 5, 2010.)

52

http://www.autodeadline.com/detail?source=Honda&mid=HON2004083172678&mime=ASC.

(Last accessed October 5, 2010.)

The second important air bag curtain design difference between rollover and side impact protection is the size or coverage of the air bag curtain. One of the most obvious trends in newer vehicles is the increasing area of coverage for rollover curtains. Referring to earlier generations of curtains, Ford has stated that its rollover protection air bags covered between 66 and 80 percent

of the first two rows of windows, and that it was expanding the designs so they cover all three rows in all models.

53

GM stated that its curtains designed for rollover protection are larger than non-rollover curtains.

54

53

Ibid.

54

Who Benefits From Side and Head Airbags?” (

http://www.edmunds.com/ownership/safety/articles/105563/article.html

), supra.

a. Existing Curtains Tested to Proposed Requirements

The agency presented data in the NPRM from testing of eight MY 2003 through MY 2006 vehicles. Since the date of publication of the NPRM, the agency tested 16 vehicle models to the proposed ejection mitigation requirements. Data from these tests supplement the data from tests of eight MY 2003 through MY 2006 vehicles discussed in the NPRM and are discussed in this section. Most of the testing of the 16 vehicle models was with the old impactor used in the NPRM tests. Tests from three vehicles were performed with a new test device (“new impactor”). To date we have performed nearly 700 impacts.

Figure 1 shows the target location key for the test results. In the data, the C1-C4 targets follow the same positioning as the B1-B4 targets. In a few instances, the A2 and A3 targets were eliminated because they were too close and a target (A5) was placed back in the window because the centers of remaining targets A1 and A4 were more than 360 mm apart.

ER19JA11.000

General Results

The results of the agency testing are given in Tables 10 through 18, below. The results are given in columns, by target location and are in units of millimeters. (The technical report accompanying this document has the data color-coded. Values exceeding the proposed 100 mm limit of impactor displacement are in red or the darkest shading. Results from 80 to 100 mm of displacement are purple or medium shading. Results which are less than 80 mm are in green or the lightest shading.) Some cells contain the average from several tests under the same/similar conditions; these results are bolded. In some tests there was so little resistance to the impactor that it continued past the countermeasure to the point where the internal limit of the impact prevented any additional displacement. In these cases, the numerical value of displacement has no meaning so the cell is denoted as “To Stops.”

On occasion, target locations were not tested at 24 km/h because the 20 km/h results indicated displacements in excess of 100 mm at that location. These cells are denoted by “(20 km/h)” and we assume the 24 km/h impact would also have exceeded 100 mm. Similarly, some target locations were not tested at 20 km/h, but the cells contain “(24 km/h)” indicating a value below 80 mm of displacement in the 24 km/h test and we assume the 20 km/h impact would have resulted in a displacement less than 80 mm.

As detailed later, some vehicles were tested with pre-broken advanced laminated (designated as “w/lam.” next to the vehicle name). Various breaking methods were used. For simplicity in presenting the data, we have averaged the results for various breaking methods, except for the method of breaking the laminated in four places (designated as “4 hole” next to the vehicle name). Also, a few tests were performed with the headliner in place (designated as “w/liner” next to the vehicle name). “N/O” refers to whether the test was conducted with the old “O” or new “N” impactor.

Across all vehicles, as was the case with our previous analysis of test data in the NPRM, target A1 remains the most challenging impact location and A4 the least challenging for the 1st row. This is consistent for all three impactor speeds and time delays. For the 2nd row, B1 and B2 are the most challenging. The available data do not present a clear trend for the 3rd row.

The two best performing vehicles were the MY 2007 Mazda CX9 and the MY 2008 Toyota Highlander. We will discuss the performance of these vehicles in more detail in several of the sections below.

Table 10—Front Row Window, 24 km/h Impact, 1.5 Second Delay

Vehicle

N/O*

Pos. A1

Pos. A2

Pos. A3

Pos. A4

03 Navigator

O

No Data

(20 km/h)

(20 km/h)

−21

03 Navigator w/lam

O

No Data

35

No Data

No Data

04 Volvo XC90

O

(20 km/h)

193

130

18

04 Volvo w/lam

O

(20 km/h)

44

118

15

05 Chevy Trailblazer

O

138

168

159

No Data

05 Chevy Trailblazer w/lam

O

No Data

No Data

(20 km/h)

No Data

05 Chevy Trail. w/lam. (4 hole)

O

No Data

89

No data

No Data

05 Honda Odyssey

O

No data

107

119

No data

05 Infinity FX35

O

128

101

99

55

05 Nissan Pathfinder

O

(20 km/h)

167

(20 km/h)

79

05 Toyota Highlander

O

(20 km/h)

137

142

116

06 Dodge Durango

O

174

156

(20 km/h)

54

06 Dodge Durango w/lam

O

No Data

101

No data

No Data

06 Dodge Dur. w/lam. (4 hole)

O

(20 km/h)

95

(20 km/h)

No Data

06 Mercury Monterey

O

To Stops

208

No data

32

06 Toyota Land Cruiser

O

229

No data

(20 km/h)

62

06 Volvo C70

O

(20 km/h)

No Target

No Target

No Target

07 Chevy Silverado

O

177

(20 km/h)

183

−1

07 Chevy Tahoe

O

To Stops

168

125

−25

07 Chevy Tahoe w/lam

O

113

100

124

No data

07 Chevy Tahoe w/lam. (4 hole)

O

No data

99

109

No data

07 Ford 500

O

(20 km/h)

160

38

07 Ford Edge

O

146

17

86

−9

07 Ford Edge

N

175

No data

155

No data

07 Ford Expedition

O

(20 km/h)

(20 km/h)

(20 km/h)

21

07 Jeep Commander

O

(20 km/h)

(20 km/h)

(20 km/h)

−62

07 Jeep Commander w/lam

O

No data

No data

148

No data

07 Mazda CX9

O

96

9

87

2

07 Mazda CX9

N

112

No data

90

No data

07 Saturn Vue

O

(20 km/h)

(20 km/h)

(20 km/h)

65

08 Dodge Caravan

O

136

84

(20 km/h)

−61

08 Ford Taurus X

O

146

73

99

−38

08 Subaru Tribeca

O

(20 km/h)

146

74

08 Toyota Highlander

O

64

41

54

12

08 Toyota Highlander

N

102

No data

77

No data

08 Toyota High. w/liner

N

90

No data

70

No data

09 Chevy Equinox

O

(20 km/h)

101

(20 km/h)

30

Average

135

104

114

21

Standard Deviation

42.1

55.8

33.7

45.9

Table 11—Front Row Window, 20 km/h Impact, 1.5 Second Delay

Vehicle

N/O*

Pos. A1

Pos. A2

Pos. A3

Pos. A4

03 Navigator

O

No Data

191

To Stops

−37

03 Navigator w/lam

O

No Data

6

No Data

No Data

04 Volvo XC90

O

163

96

119

−3

04 Volvo w/lam

O

127

27

97

(24 km/h)

05 Chevy Trailblazer

O

112

121

127

No Data

05 Chevy Trailblazer w/lam

O

86

80

109

No Data

05 Chevy Trail. w/lam. (4 hole)

O

No Data

62

98

No Data

05 Honda Odyssey

O

No data

96

57

−45

05 Infinity FX35

O

106

60

73

30

05 Nissan Pathfinder

O

192

138

248

60

05 Toyota Highlander

O

168

137

115

76

06 Dodge Durango

O

160

140

180

18

06 Dodge Dur. w/lam. (4 hole)

O

106

71

150

No Data

06 Mercury Monterey

O

185

199

No data

−10

06 Toyota Land Cruiser

O

174

No data

256

31

06 Volvo C70

O

200

No Target

No Target

No Target

07 Chevy Silverado

O

142

187

130

(24 km/h)

07 Chevy Tahoe

O

104

110

87

(24 km/h)

07 Chevy Tahoe w/lam

O

102

No data

No data

No data

07 Ford 500

O

192

113

(24 km/h)

07 Ford Edge

O

129

(24 km/h)

No data

(24 km/h)

07 Ford Edge

N

148

No data

67

No data

07 Ford Expedition

O

151

To Stops

137

(24 km/h)

07 Jeep Commander

O

To Stops

175

155

(24 km/h)

07 Jeep Commander w/lam

O

No data

No data

73

No data

07 Mazda CX9

N

76

No data

67

No data

07 Saturn Vue

O

To Stops

130

191

28

08 Dodge Caravan

O

112

No data

162

(24 km/h)

08 Ford Taurus X

O

110

No data

No data

(24 km/h)

08 Subaru Tribeca

O

180

106

(24 km/h)

09 Chevy Equinox

O

149

No data

200

(24 km/h)

Average

140

112

132

15

Standard Deviation

36.5

55.7

56.7

39.0

Table 12—Front Row Window, 16 km/h Impact, 6 Second Delay

Vehicle

N/O*

Pos. A1

Pos. A2

Pos. A3

Pos. A4

03 Navigator

O

To Stops

74

To Stops

−30

03 Navigator w/lam

O

157

−36

137

No Data

04 Volvo XC90

O

161

73

78

−22

04 Volvo w/lam

O

96

26

59

No Data

05 Chevy Trailblazer

O

121

192

124

No Data

05 Chevy Trailblazer w/lam

O

No Data

102

No Data

No Data

05 Chevy Trail. w/lam. (4 hole)

O

No Data

92

No Data

No Data

05 Honda Odyssey

O

No Data

69

77

−54

05 Infinity FX35

O

88

22

40

9

05 Nissan Pathfinder

O

117

104

195

43

05 Toyota Highlander

O

205

210

152

69

06 Dodge Durango

O

138

135

167

13

06 Dodge Durango w/lam

O

No Data

No Data

142

No Data

06 Dodge Dur. w/lam. (4 hole)

O

97

58

145

No Data

06 Mercury Monterey

O

222

183

No Data

35

06 Toyota Land Cruiser

O

146

207

229

16

06 Volvo C70

O

135

No Target

No Target

No Target

07 Chevy Silverado

O

145

244

115

−7

07 Chevy Tahoe

O

42

6

10

−136

07 Ford 500

O

151

58

−16

07 Ford 500 w/lam

O

96

No Data

No Data

No Data

07 Ford Edge

O

103

−42

7

−56

07 Ford Edge

N

123

No Data

33

No Data

07 Ford Expedition

O

141

205

109

3

07 Jeep Commander

O

255

144

136

−89

07 Jeep Commander w/lam

O

No Data

56

62

No Data

07 Jeep Commander w/lam. (4 hole)

O

No Data

50

60

No Data

07 Mazda CX9

O

54

−38

44

−53

07 Mazda CX9

N

67

No Data

31

No Data

07 Saturn Vue

O

184

180

186

72

08 Dodge Caravan

O

85

−39

121

−141

08 Ford Taurus X

O

104

−13

39

−88

08 Subaru Tribeca

O

122

77

−1

08 Toyota Highlander

O

36

0

54

−62

08 Toyota Highlander

N

119

No Data

52

No Data

09 Chevy Equinox

O

125

25

178

−46

Average

125

82

99

−25

Standard Deviation

50.1

87.2

61.1

58.1

Table 13—Second Row Window, 24 km/h Impact, 1.5 Second Delay

Vehicle

N/O*

Pos. B1

Pos. B2

Pos. B3

Pos. B4

03 Ford Navigator

O

To Stops

No data

No data

40

04 Volvo XC90

O

(20 km/h)

No data

No data

69

04 Volvo XC90 w/lam

O

92

No data

No data

62

05 Chevy Trailblazer

O

122

No data

No data

35

05 Honda Odyssey

O

152

193

71

80

05 Infinity FX35

O

148

No data

No data

47

05 Nissan Pathfinder

O

167

No data

No data

133

05 Toyota Highlander

O

152

No data

No data

154

06 Dodge Durango

O

86

82

76

91

06 Mercury Monterey

O

171

193

72

78

06 Toyota Land Cruiser

O

159

157

75

No Target

07 Chevy Silverado

O

153

(20 km/h)

78

117

07 Chevy Tahoe

O

(20 km/h)

161

24

74

07 Chevy Tahoe w/lam

O

No data

48

No data

No data

07 Ford 500

O

184

50

102

157

07 Ford 500 w/lam

O

91

No data

No data

111

07 Ford 500 w/lam. (4 hole)

O

No data

No data

No data

99

07 Ford Edge

O

39

21

−22

27

07 Ford Edge

N

51

33

No data

26

07 Ford Expedition

O

164

55

66

75

07 Jeep Commander

O

140

(20 km/h)

64

No data

07 Mazda CX9

O

36

2

51

9

07 Mazda CX9

N

22

No data

44

No data

07 Saturn Vue

O

No Target

144

66

No Target

08 Dodge Caravan

O

59

27

−16

−7

08 Ford Taurus X

O

45

34

22

31

08 Subaru Tribeca

O

133

85

80

111

08 Toyota Highlander

O

106

110

55

109

08 Toyota Highlander

N

125

144

No data

133

08 Toyota High. w/liner

N

133

138

No data

77

09 Chevy Equinox

O

72

22

39

45

Average

112

89

53

76

Standard Deviation

49.2

63.0

32.7

44.0

Table 14—Second Row Window, 20 km/h Impact, 1.5 Second Delay

Vehicle

N/O*

Pos. B1

Pos. B2

Pos. B3

Pos. B4

03 Ford Navigator

O

To Stops

No data

No data

−14

04 Volvo XC90

O

183

No data

No data

(24 km/h)

04 Volvo XC90 w/lam

O

94

No data

No data

(24 km/h)

05 Chevy Trailblazer

O

68

No data

No data

8

05 Honda Odyssey

O

134

84

42

34

05 Infinity FX35

O

90

No data

No data

21

05 Nissan Pathfinder

O

143

No data

No data

111

05 Toyota Highlander

O

110

No data

No data

106

06 Mercury Monterey

O

155

52

42

51

06 Toyota Land Cruiser

O

127

128

53

No Target

07 Chevy Silverado

O

114

232

(24 km/h)

101

07 Chevy Tahoe

O

249

No data

(24 km/h)

(24 km/h)

07 Ford 500

O

152

No data

89

128

07 Ford Expedition

O

146

23

(24 km/h)

(24 km/h)

07 Jeep Commander

O

122

107

(24 km/h)

No data

07 Saturn Vue

O

No Target

111

40

No Target

08 Subaru Tribeca

O

105

No data

(24 km/h)

No data

08 Toyota Highlander

O

No data

67

(24 km/h)

88

08 Toyota Highlander

N

92

89

No data

110

Average

130

99

53

64

Standard Deviation

43.4

59.3

20.7

49.9

Table 15—Second Row Window, 16 km/h Impact, 6 Second Delay

Vehicle

N/O*

Pos. B1

Pos. B2

Pos. B3

Pos. B4

03 Ford Navigator

O

126

No data

No data

−27

04 Volvo XC90

O

189

No data

No data

29

04 Volvo XC90 w/lam

O

63

No data

No data

9

05 Chevy Trailblazer

O

127

No data

No data

47

05 Honda Odyssey

O

121

28

12

55

05 Infinity FX35

O

64

No data

No data

20

05 Nissan Pathfinder

O

111

No data

No data

78

05 Toyota Highlander

O

143

No data

No data

110

06 Dodge Durango

O

36

18

3

71

06 Mercury Monterey

O

223

142

54

54

06 Toyota Land Cruiser

O

107

113

49

No Target

07 Chevy Silverado

O

124

194

53

63

07 Chevy Tahoe

O

120

−83

−21

15

07 Chevy Tahoe w/lam

O

66

No data

No data

No data

07 Chevy Tahoe w/lam. (4 hole)

O

58

No data

No data

No data

07 Ford 500

O

133

−3

56

94

07 Ford 500 w/lam

O

64

No data

No data

No data

07 Ford Edge

O

−16

−40

−76

−25

07 Ford Expedition

O

89

159

22

34

07 Jeep Commander

O

107

99

27

57

07 Mazda CX9

O

−15

−58

5

−35

07 Saturn Vue

O

No data

138

26

No data

08 Dodge Caravan

O

−58

−29

−55

−56

08 Ford Taurus X

O

−17

−19

−13

−40

08 Subaru Tribeca

O

76

19

28

20

08 Toyota Highlander

O

49

59

32

57

08 Toyota Highlander

N

87

105

No data

93

09 Chevy Equinox

O

15

−51

1

−14

Average

81

44

12

31

Standard Deviation

63.9

84.5

37.2

46.8

Table 16—Third Row Window, 24 km/h Impact, 1.5 Second Delay

Vehicle

N/O*

Pos. C1

Pos. C2

Pos. C3

Pos. C4

05 Honda Odyssey

O

No data

(20 km/h)

No data

175

06 Mercury Monterey

O

188

(20 km/h)

119

No data

06 Toyota Land Cruiser

O

NC

NC

180

NC

07 Chevrolet Tahoe

O

91

No Target

194

No Target

07 Chevrolet Tahoe w/lam

O

No Data

106

141

No Data

07 Ford Expedition

O

(20 km/h)

No data

81

186

07 Jeep Commander

O

229

155

120

102

08 Dodge Caravan

O

−42

112

35

−41

08 Ford Taurus X

O

No Target

To Stops

48

No Target

08 Toyota Highlander

O

−42

42

92

No data

08 Toyota Highlander

N

No data

No data

110

No data

08 Toyota Highlander w/liner

N

No data

No data

42

No data

Average

85

104

106

106

Standard Deviation

126.1

46.6

53.1

104.5

Table 17—Third Row Window, 20 km/h Impact, 1.5 Second Delay

Vehicle

N/O*

Pos. C1

Pos. C2

Pos. C3

Pos. C4

05 Honda Odyssey

O

No data

To Stops

58

122

06 Dodge Durango

O

No data

To Stops

66

No data

06 Mercury Monterey

O

147

212

75

No data

06 Toyota Land Cruiser

O

NC

NC

128

NC

07 Chevrolet Tahoe

O

58

No Target

No data

No Target

07 Ford Expedition

O

241

No data

No data

51

07 Jeep Commander

O

No data

115

102

No data

08 Ford Taurus X

O

No Target

86

(24 km/h)

No Target

08 Toyota Highlander

N

No data

No data

88

No data

Average

149

138

86

86

Standard Deviation

91.5

66.0

25.8

50.6

Table 18—Third Row Window, 16 km/h Impact, 6 Second Delay

Vehicle

N/O *

Pos. C1

Pos. C2

Pos. C3

Pos. C4

05 Honda Odyssey

O

To Stops

To Stops

44

80.

06 Dodge Durango

O

No Data

No Data

52

No Data.

06 Mercury Monterey

O

186

204

142

225.

06 Toyota Land Cruiser

O

NC

NC

98

NC.

07 Chevrolet Tahoe

O

30

No Target

64

No Target.

07 Chevrolet Tahoe w/lam

O

No Data

57

66

No Data.

07 Ford Expedition

O

233

No Data

49

34.

07 Jeep Commander

O

170

104

92

56.

08 Dodge Caravan

O

−91

34

−42

−113.

08 Ford Taurus X

O

No Target

60

7

No Target.

08 Toyota Highlander

O

No Data

−23

37

No Data.

Average

106

73

55

56.

Standard Deviation

133.4

76.5

48.2

120.6.

Trends in Performance of Ejection Mitigation Systems by MY Using Old Impactor

Based on the vehicles the agency tested, there appears to be a trend toward improved performance as each model year passes. This is demonstrated by increased coverage of the window opening in the more recent MY vehicles tested and the ability of the countermeasure to restrain displacement of the impactor. While it is difficult to quantify this trend, the trend is shown graphically below by plots of displacement values by model year for the 1st row (Figure 2) and 2nd Row (Figure 3). These graphs are restricted to the 24 km/h-1.5 second test using the old impactor and exclude any testing with advanced glazing.

Note:

Not shown in the figure are data from older vehicles which often had no curtain coverage at a particular target. If there was no curtain coverage, we did not test the target since the 100 mm displacement limit would have been exceeded. Although these vehicles are not shown on the graph, their improved curtain coverage in recent MY vehicles is indicative of improved performance over time.

Since the graphs span multiple vehicles, there is scatter in the data. Nonetheless, when a trend line is plotted through the data for each impact location it shows decreasing displacement for newer models.

ER19JA11.001

ER19JA11.002

One comparison to note for illustration purposes is the improved performance of the MY 2008 Highlander in comparison to the MY 2005 Highlander. Table 19 shows the change in displacement values for the two model years of the Highlander at each target location and across impact speeds. The largest change in displacement value was for the 16 km/h tests at targets A1 and A2 (169 mm and 210 mm, respectively). On an average basis, the MY 2008 Highlander had 103 mm less displacement across all tested target locations, for a 76 percent overall reduction. This is illustrative of the improved performance of later MY vehicles. We believe that the MY 2008 Highlander had increased coverage of the ejection mitigation curtain and increased size of the inflated chambers which helped to restrain the impactor.

Table 19—Old Impactor, Absolute and Percentage Change in Displacement (mm) Between MY2005 and MY2008 Toyota Highlander

Test vel.

A1

A2

A3

A4

B1

B4

24

−96

−88

−104

−46

−45

16

−169

−210

−98

−131

−94

−53

Average (mm)

−103

24

−70%

−62%

−90%

−30%

−29%

16

−82%

−100%

−64%

−190%

−66%

−48%

Average (%)

−76%

Comparing Results of Tests With Old and New Impactors

Several vehicles (the MY2008 CX9, Edge and Highlander) were tested using both the old and new impactor.

Table 20 shows the difference in displacements measured at target locations where both impactors were used.

55

Not surprisingly, these data generally indicate that the new impactor tends to result in greater displacement (positive difference); we believe this is due to lower dynamic friction. Yet, the old impactor displacement exceeded the new impactor (negative difference) at several targets as well.

55

In some cases average values were used to calculate the differences.

The CX9 was the only vehicle that was impacted multiple times at the same targets by both the old and new

impactor. A student's t-test was performed to determine if the difference in the results were significant.

56

Table 21 shows the displacement values and statistics for targets A1 and A3. The difference in displacement was statistically significant (p≤0.05) for the A1 target, but not the A3 target.

56

The one sided t-test was performed assuming equal variance to determine if the new test device had produced larger displacement values compared to the old device.

Table 20—Change in Displacement Between Old and New Impact Test Device

Vehicle

Test vel.

(km/h)

A1

A3

B1

B2

B3

B4

C3

08 Ford Edge

24

29.0

69.0

12.0

12.0

−1.0

08 Mazda CX9

24

15.5

3.0

−14.0

0.0

−7.0

0.0

08 Toyota Highlander

24

38.5

23.0

19.0

34.0

24.0

18.0

08 Ford Edge

20

18.5

08 Toyota Highlander

20

22.0

22.0

08 Ford Edge

16

19.5

26.0

08 Mazda CX9

16

13.0

−13.0

08 Toyota Highlander

16

83.0

−2.0

38.0

46.0

36.0

Average

31.0

17.7

13.8

28.5

−7.0

20.3

18.0

Average All

21.6

Table 21—Impactor Comparison for Mazda CX9

Test Vel.

(km/h)

A1

Old

New

A3

Old

New

24

94

110

84

90

98

113

89

89

Average

96.0

111.5

86.5

89.5

Std.

2.8

2.1

3.5

0.7

P-Value

0.013

0.180

Despite the differences in test results, the test results from the old impactor provided useful data to assess the relative performance of ejection mitigation countermeasures. The results from the impactor are useful when analyzing data obtained from the old impactor alone, to compare vehicles to each other or to previous model year vehicles, or compare data from impact points on a vehicle.

Research Testing With New Impactor

As part of our analysis of the data, we evaluated data from only the new impactor to avoid confounding the comparison of data by impactor differences. Table 22 shows the change in displacement between the 24 km/h-1.5 second, 20 km/h-1.5 second and 16 km/h-6 second tests at various target locations for the MY 2007 Edge, MY 2007 CX9 and MY 2008 Highlander. The 24 km/h-1.5 second test always had greater displacement than the 20 km/h-1.5 second test. On average this difference was 38.3 mm when averaged over all vehicles and target locations. This is an expected result because the only difference is the impact speed.

Table 22—New Impactor, Change in Displacement (mm) Between 24 km/h 1.5 Second, 20 km/h 1.5 Second and 16 km/h 6 Second Tests

Vehicle

Test

comparison

A1

A3

B1

B2

B4

C3

07 Ford Edge

24-20

28

88

07 Mazda CX9

24-20

36

23

08 Toyota Highlander

24-20

33

55

23

22

07 Ford Edge

24-16

53

122

07 Mazda CX9

24-16

45

59

08 Toyota Highlander

24-16

−17

25

38

39

40

07 Ford Edge

20-16

25

34

07 Mazda CX9

20-16

9

36

08 Toyota Highlander

20-16

5

−16

17

Average All—24-20

38.3

Average All—24-16

44.7

Average All—20-16

15.7

There were only two vehicles/target locations that had more than one impact at multiple test speeds. Although this is extremely limited data, they allow a t-test to be performed.

57

The results are given in Table 23. The results indicate that the 16 km/h-1.5 second impact had statistically significant less displacement than both the higher speed tests at target A1.

57

The one sided t-test was performed assuming equal variance to determine if the 24 km/h impact produced larger displacement values compared to the 20 km/h impact.

Table 23—New Impactor, Comparison of Target A1 Displacement as a Function of Impact Velocity

Vehicle

Test Type

CX9

16 km/h-6 sec.

24 km/h-1.5 sec.

Edge

16 km/h-6 sec.

20 km/h-1.5 sec.

75

110

126

152

59

113

119

143

Average

67.0

111.5

122.5

147.5

Std.

11.3

2.1

4.9

6.4

P-Value

0.016

0.024

b. Field Performance

The agency evaluated available crash data to better understand the field performance of the current fleet equipped with side curtain air bags. A focus of this evaluation was the performance of the rollover sensors and their ability to detect the rollover event and activate deployment of the side curtain air bags. We also sought to understand the occupant containment provided by the vehicle system. Several sources of available data were reviewed. These included detailed analysis on a limited number of rollover crashes by NHTSA's Special Crash Investigation (SCI) division, case reviews of NASS CDS cases from the target population of the final rule, and data from a new Rollover Data Special Study project. Detailed reviews of some of these cases can be found in the technical report accompanying this final rule.

SCI Cases Presented in the NPRM

The following seven SCI cases were discussed in the NPRM. The agency's SCI division analyzed seven real-world rollover crashes of Ford vehicles where the subject vehicles contained a rollover sensor and side curtain air bags. (Ford had agreed to notify SCI of the crashes.) The subject vehicles were Ford Expeditions, a Ford Explorer, a Mercury Mountaineer, and a Volvo XC90. Table 24 gives details about each case.

In each case, the rollover sensor deployed the side curtain air bag. Of the seven cases, there were a total of 19 occupants, 15 of whom were properly restrained. All were in lap/shoulder belts, except one child in a rear facing child restraint system (CRS). A single crash (DS04-016) had all of the unrestrained occupants, serious injuries, fatalities and ejections in this set of cases. Two of the four unrestrained occupants were fully ejected from the vehicle, resulting in one fatal and one serious injury. The fatality was a 4-month-old infant, seated in the middle of the 2nd row. The ejection route was not determined. The seriously injured occupant was an adult in the left 3rd row, ejected through the uncovered right side 3rd row window. One non-ejected, restrained occupant received a fatal cervical fracture resulting from roof contact and another was seriously injured. The injuries to the remaining occupants were “none” to “minor.”

Table 24—Ford SCI Rollover Cases (Presented in the NPRM)

Case

Make

Model

MY

Occupants

Row 1

Row 2

Row 3

1/4

Rot.

Deploy

Angle

Time (ms)

Rate (deg/s)

CA02-059

Mercury

Mount.

2002

1R

1R

1

17

17 to 25

CA04-010

Ford

Expl.

2003

1R

1

43

20

75

IN-02-010

Ford

Exped.

2003

1R

2

45

146

111

2004-003-04009

Ford

Exped.

2003

1R

2R

5

Yes

Unknown

Unknown

DS04-016

Ford

Exped.

2003

2R

2R, 2NR†

1R, 2NR†

5

Yes

Unknown

Unknown

DS04017

Ford

Exped.

2004

1R

12

Yes

Unknown

Unknown

2003-079-057

Volvo

XC90

2003

1R

1R

6

Yes

Unknown

Unknown

R = Restrained, NR = Not Restrained.

† One NR 2nd and 3rd row occupant ejected (total of 2 ejected).

Rollover Data Special Study (RODSS)

RODSS is a new source of rollover crash data that began in April 2007. NHTSA initiated RODSS as a pilot project to obtain additional field data for rollover crashes not covered by other agency databases. Cases were identified through the FARS database. NASS CDS and SCI cases were excluded from consideration because detailed information from those crashes would be available from those databases. However, remote SCIs were performed on selected cases.

58

The technical report for this final rule includes a discussion of the RODSS study conducted for this final rule.

58

A remote SCI is one where, for a variety of reasons, the investigator is not able to physically examine the crash location and vehicles. The investigation is done through the use of police accident reports, scene diagrams and photographs.

RODSS is not a random sample and is not intended to be statistically representative of all rollover crashes nationally. Also, the sample size is small and becomes even smaller when separating the data into subcategories. Accordingly, observations based on the RODSS data about the relationship of side curtains and ejection are inherently limited.

To become part of the RODSS sample, the vehicle had to be exposed to a rollover crash and have a side curtain air bag and/or electronic stability control (ESC)/rollover stability control (RSC). The curtain air bag did not have to be deployable in a rollover, i.e., the curtain air bag could be an FMVSS No. 214 side impact air curtain without a rollover sensor, but some vehicles did have a rollover sensor.

The study first reviewed a total of 328 crashes occurring in 2005 through 2008. Of these 328 case vehicles, 315 were coded as exposed to a lateral rollover. Of these 315 case vehicles, 115 were believed to be equipped with side curtain air bags. Of these 115 case vehicles, 21 were believed to have a rollover sensor (rollover curtain). Of these 21 case vehicles, 18 had their curtains deploy during the rollover and 3 did not. These three cases of non-deployment are of interest relative to sensor performance and will be discussed in more detail later, along with a non-deployment SCI case.

Curtain deployment coding was tied to the driver or passenger, i.e., if there was someone seated on the side of the vehicle where the curtain deployed, it was coded as deployed for that occupant. There were 120 side curtain air bags deployed adjacent to occupants of the vehicles (58 drivers and 62 passengers). Limiting RODSS occupant selection to those in vehicles exposed to a lateral rollover, and those who had a known ejection status, then separating by known curtain deployment, results in Table 25, below. This table shows 119 occupants (57 drivers and 62 passengers) who were exposed to a curtain deployment and 496 (244 drivers and 252 passengers), who were not.

Table 25—RODSS Driver and Passenger in Lateral Rollovers With Known Ejection Status by Known Curtain Deployment

Curtain deployment

Drivers

Passengers

All occupants

Yes

57

62

119

No

244

252

496

Total

301

314

615

General Observations From RODSS About Ejection Rates Relative to Curtain Air Bags

Again, any observations made based on the RODSS data about the relationship of side curtains and ejection must be prefaced by the fact that RODSS is not a random sample and is not intended to be statistically representative of all rollover crashes nationally.

The data from the 615 occupants in Table 25 form the basis of a comparison on ejection status versus curtain air bag deployment found in Tables 26 and 27. The “curtain deployed” group is made up of vehicles that had a rollover sensor and vehicles that did not (the latter vehicles may have had a side impact sensor only). The “curtain not deployed” group is made up of vehicles equipped or not equipped with a curtain, i.e., one possible reason for the curtain not deploying is that it did not exist.

We studied the data to see if side curtains had an effect in mitigating rollover ejections. We were aware that care should be taken in drawing conclusions from these results. Most of the curtain-equipped vehicles exposed to lateral rollovers had only FMVSS No. 214 side impact curtains (94 vehicles), rather than rollover curtains (21 vehicles). It is possible that if a side impact curtain deployed during the crash, the crash might be different than a crash where a side impact curtain did not deploy. An important difference when examining ejection data is rollover severity as quantified by number of quarter-turns. To help determine if there was an obvious bias in the data, we examined the difference between the quarter-turns in the rollover crashes where the side impact curtains deployed and the number of quarter turns in the rollover crashes where they did not deploy.

RODSS data indicate that deployment of any curtain (even a side impact curtain) has a positive effect on reducing the rate of side window ejection. Table 26 shows that 10.9 percent [13/119] of all occupants adjacent to a curtain air bag deployment were ejected through the side windows, in comparison to 27.6 percent [137/496] of those occupants who were not adjacent to a curtain deployment.

Restricting the data to occupants protected by a curtain deployed by a rollover sensor, 5.3 percent [2/38] were ejected. The cases involving the two occupants who were ejected, even though the rollover curtain deployed, are discussed in a later section.

ER19JA11.003

Table 27 examines the subset of occupants from Table 26 who were unbelted. Table 27 shows that 22.7 percent [10/44] of unbelted occupants in vehicles with curtain air bag deployment were ejected through the side windows, in comparison to 51.9 percent [108/208] of those unbelted occupants in vehicles where the curtain did not deploy. Rollover severity (as represented by number of quarter-turns) does not seem to account for the difference in the ejection rates for these two unbelted groups.

When the data are restricted to only unbelted occupants protected by rollover curtains, 10.0 percent [1/10] were ejected through the side window, as compared to 26.5 percent [9/34] of unbelted occupants protected by side impact curtains. We note that two unbelted occupants were not ejected in vehicles with deployed rollover curtains.

ER19JA11.004

Cases Where Occupants Were Ejected Through Rollover Curtain-Equipped Windows

We examined SCI rollover crashes, NASS CDS cases from the target population of the final rule and data from the RODSS project and found six case vehicles where occupants were ejected through the side window opening that a rollover deployed curtain presumably covered. These cases are listed in Table 28, along with the number of quarter turns, occupant seating position, belt use, occupant age, degree of ejection, ejection route, and level of injury.

The average number of quarter-turns was 5.5. These six crashes involved nine occupants, six of whom were partially or completely ejected through a protected side window. Four occupants were partially ejected and two were completely ejected. All six were front seat occupants, although one was ejected through a second row window. Four of the ejected occupants were killed in the crash. One fatal partial ejection was ejected through a window protected by both a curtain and a laminated window. Four of these cases involved curtain damage. In two, the A-pillar tether detached. It is not possible to know if these instances of curtain damage occurred during the rollover or post-crash due to extrication.

Table 28—RODSS, NASS CDS and SCI Cases With Occupants Who Were Ejected Through Side Windows Protected by Rollover Curtains

Case ID

Year/Make/Model

1/4

Turns

Curt.

depl.

Seat

pos.

Belt

use

Age

Eject.

Route

Injury/

MAIS

RODSS

7238 *

06 Ford Explorer

6

Yes

11

No

84y

Comp.

Row 1 L

Fatal.

8289 *

03 Lincoln Aviator ‡

8+

Yes

11

Yes

62y

Part

Row 1 L

Fatal.

8289 *

03 Lincoln Aviator ‡

8+

Yes

12

Yes

28y

No

NA

Serious.

8289 *

03 Lincoln Aviator

8+

Yes

23

Yes

65y

No

NA

Moderate.

NASS CDS

2003-04-048 *

02 Ford Explorer

4

Yes

11

Yes

54y

No

NA

1.

2003-04-048

02 Ford Explorer

4

Yes

13

Yes

49y

Part

Row 1 R

1.

2006-79-089

04 Lexus RX330

1

Yes

11

No

27y

Part

Row 2 L

Fatal.

2008-03-108

08 Honda Pilot

6

Yes

11

No

48y

Part

Row 1 L

3.

2008-12-159

05 Mercury Mont

8

Yes

11

No

23y

Comp.

Row 1 L

Fatal.

* These are also SCI cases.

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‡ These seating positions had laminated glazing adjacent to them.

Non-Deployed Rollover Curtains in Rollover Crashes

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Both RODSS cases were made into SCI remote investigations to facilitate documentation of photographs and other crash details. The SCI case numbers are CA09069 (RODSS 7238) and CA10006 (RODSS 8289).

We examined SCI rollover crashes, NASS CDS cases from the target population of the final rule and data from the RODSS project to find if the rollover sensors deployed the rollover side air curtains in a rollover. In general, field data indicate that rollover sensors have been recognizing a rollover and deploying rollover curtains in rollover crashes.

We found five case vehicles where the vehicle was apparently equipped with a side curtain air bag that was supposed to be deployed by a rollover sensor and the curtains did not deploy in the rollover event (

see

Table 29). There were two completely ejected occupants and one partial ejected occupant in these crashes. The results of these ejections were 3 fatalities. All of these ejections were through side windows except one where the front passenger door was dislodged from the vehicle and provided the ejection route for the unbelted driver.

Consistent among these non-deployment cases is that the rollover was preceded by a significant frontal impact. Four of the five non-deployment cases had a significant frontal impact that preceded the rollover. The MY 2006 Ford Explorer in RODSS case 6121 had a right front corner impact with a large tree prior to the rollover. The MY 2003 Lincoln Aviator in RODSS case 7242 had an offset frontal impact with an oncoming vehicle prior to the rollover. The MY 2006 Cadillac SRX in SCI case DS07009 impacted a large tree prior to the rollover. The EDR data from this case indicated that the tree impact had a longitudinal and lateral ΔV of − 38.9 mph and − 10.2 mph, respectively. The EDR also indicated that the rollover sensor status was “invalid” and the curtain deployment was not commanded. The MY 2009 Dodge Journey had a narrow offset frontal impact with another vehicle, which the crash investigator stated disrupted the power supply from the battery. The frontal air bags deployed in the above four crashes. (There is some doubt as to whether RODSS case 6121 (SCI CA9062) was definitely equipped with a rollover sensor, since the system was an option on this vehicle. Ultimately, no definitive determination was made.) For the cases involving initial frontal impacts, these impacts may have destroyed the vehicle battery and thus eliminated the primary power source for deploying the rollover curtain.

In RODSS case 5032 (SCI CA9061), it appears the sensor may not have been able to make a determination that a rollover occurred. However, in studying the details of this case, the vehicle's kinematics were very complex and may have included some motion not typical of a lateral rollover.

Table 29—RODSS and SCI Rollover Cases Where the Rollover Curtain Did Not Deploy

Case ID

Year/Make/Model

Quarter turns

Curt. depl.

Seat pos.

Belt use

Age

Eject.

Route

Injury/

MAIS

RODSS

5032 *

04 Lincoln Aviator ‡

3

No

11

No

68y

Comp.

Row 2 R

Fatal.

6121 *

06 Ford Explorer

4

No

11

No

23y

Comp.

Door (13)

Fatal.

7242 *

03 Lincoln Aviator ‡

3

No

11

Yes

28y

No

NA

Serious.

7242 *

03 Lincoln Aviator ‡

3

No

13

Yes

26y

No

NA

Serious.

7242 *

03 Lincoln Aviator

3

No

21

CRS

3y

No

NA

Serious.

7242 *

03 Lincoln Aviator

3

No

23

Yes

7y

No

NA

Serious.

SCI

DS07009

06 Cadillac SRX

4

No

11

No

81y

Part

Row 1 L

Fatal.

DS09071

09 Dodge Journey

4

No

11

Yes

63y

No

NA

2.

DS09071

09 Dodge Journey

4

No

13

Yes

60y

No

NA

1.

* These are also SCI cases.

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‡ These seating positions had laminated glazing adjacent to them.

X. Response

to Comments and Agency Decisions

60

These three RODSS cases were made into SCI remote investigations to facilitate documentation of photographs and other crash details. The SCI case numbers are RODSS 5032 (CA09061), RODSS 6121 (CA9062) and RODSS 7242 (CA9063).

Laboratory and field data indicate that window curtains covering side windows can substantially reduce ejections in rollovers. NHTSA issued the NPRM to require that the side windows next to the first three rows of seats be subject to performance requirements that ensure the vehicle has an ejection mitigation countermeasure that would prevent an 18 kg headform from moving more than 100 mm beyond the zero displacement plane of each window when the window is impacted.

The NPRM proposed requirements for: (a) The impactor dimensions and mass; (b) the displacement limit; (c) impactor time and speed of impact; (d) target locations, and (e) testing the targets. We also discussed: (f) glazing issues; (g) test procedure tolerances; (h) test device characteristics; and (i) a proposal for a telltale requirement. The NPRM did not specifically require a rollover sensor. A 3-year lead time and 4-year phase-in was proposed, along with allowance of advanced credits to meet phase-in requirements. Costs, benefits, and other impacts were discussed in a PRIA accompanying the NPRM.

a. Impactor Dimensions and Mass

1. NPRM

The component test involves use of a guided linear impactor that is designed to replicate the loading of a 50th percentile male occupant's head and upper torso during ejection situations. The portion of the impactor that strikes the countermeasure is a featureless headform that was originally designed for the upper interior head protection research program (FMVSS No. 201).

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It averages the dimensional and inertial characteristics of the frontal and lateral regions of the head into a single headform. The NPRM specified that the headform is covered with an approximately 10 mm thick dummy skin material whose outer surface dimensions are given in Figure 4, below. The Technical Analysis report accompanying the NPRM discusses other dimensional attributes of the headform, such as the curvature of the outer surface.

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“Ejection Mitigation Using Advanced Glazings: A Status Report,” November 1995, Docket NHTSA-1996-1782-3; “Ejection Mitigation Using Advanced Glazings: Status Report II,” August 1999, Docket NHTSA-1996-1782-21; “Ejection Mitigation Using Advanced Glazings: Final Report,” August 2001, Docket NHTSA-1996-1782-22.

There are many possible ways of delivering the impactor to the target location on the ejection mitigation countermeasure. Both the old and new impactors used in agency research propel the shaft component of the impactor with a pneumatic piston. The shaft of the old impactor slides along a plastic (polyethylene) bearing. The new impactor uses curved roller bearings for part of the shaft support, which reduces the energy loss due to friction. The impactor has an 18 kg mass.

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Since the performance criterion for this ejection mitigation standard is a linear displacement measure (a linear displacement measure would correlate to the actual gap through which an occupant can be ejected), a linear impactor is a suitable tool to dynamically measure displacement. The impactor can be placed inside the vehicle for testing the ejection mitigation curtains and glazing covering window openings.

ER19JA11.005

The mass of the guided impactor was developed through pendulum tests, side impact sled tests, and modeling conducted to determine the mass imposed on the window opening by a 50th percentile adult male's upper torso and head during an occupant ejection (“effective mass”).

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Briefly, the pendulum impact tests were conducted on a BioSID anthropomorphic test device (50th percentile adult male) to measure effective mass of the head, shoulder, and upper torso. The BioSID was chosen because it was originally configured for side impact, unlike the Hybrid III dummy, and has a shoulder which the Side Impact Dummy (49 CFR 572, subpart F) used for FMVSS No. 214, “Side impact protection,” does not have. A linear impact pendulum weighing 23.4 kg was used to strike the head and shoulder of the dummy laterally (perpendicular to the midsagittal plane) using two impact speeds (9.7 and 12.9 km/h) and four impact surfaces. In addition to the rigid impactor face, three types of padding were added to the impactor face to increase the contact time and replicate advanced glazing impacts.

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“Technical Analysis in Support of a Notice of Proposed Rulemaking for Ejection Mitigation,”

supra.

Effective mass was calculated by dividing the force time history calculated from the pendulum accelerometers by the acceleration time history from the dummy sensors. In general, higher speed impacts and impacts with softer surfaces generated higher effective mass. Based on these pendulum tests, a range for the effective mass of the head and upper torso was estimated to be 16 to 27 kg.

In the sled tests, we used a side impact sled buck with a load plate representing a door and two load plates representing the glazing to measure shoulder and head impacts with three different stiffness foams. The purpose of these tests was to determine the effect lower body loading would have on the combined head and upper torso effective mass. Two impact conditions were simulated, one condition was described as being representative of a rollover event and the second was described as being representative of a side impact event.

In the rollover condition, the impact speed was intended to be 16.1 km/h (10 mph) and the dummy was positioned leaning towards the door such that the head and torso would contact the simulated glazing at the same time. This leaning position was intended to be more representative of an occupant's attitude in a rollover. For the test designed to be more representative of a side impact condition, the dummy was seated upright and the impact speed was intended to be 24.1 km/h (15 mph).

In the preamble of the NPRM, we described the agency's analysis of these tests as follows. As was done for the pendulum data, the effective mass was calculated by dividing the force time history calculated from the pendulum accelerometers by the acceleration time history from the dummy sensors. Using this method, the effective mass of the head and upper torso calculated for the 16.1 km/h impact condition showed a quick rise to about 18 kg by about 5 ms, followed by an increase to about 40 kg at about 30 ms. The effective mass for the 24.1 km/h impact condition showed an initial artificially high value or spike prior to 5 ms because of a lag between the force measured in the load plates and the acceleration measured at the upper spine. This spike was also seen in some pendulum shoulder impacts. The effective mass settled to about 9 kg at about 10 ms, with a slow rise to about 18 to 20 kg at about 25 to 30 ms. Looking at the results, we deferred to the 18 kg effective mass since the test condition more closely represented a rollover. In addition, the 18 kg value was within the range of the pendulum impactor results discussed above, which showed an effective mass range between 16 and 27 kg.

For this final rule, we have reanalyzed these sled tests primarily for the purpose of determining impact energy, which we address in detail later in this preamble.

64

However, this analysis also generated estimates of the effective mass of the dummies in these tests. For the 24.1 km/h test, three methods (represented by equations 2-4,

infra

) gave a range of the combined head and shoulder effective mass of 12.2 to 13.1 kg. We believe that a reasonable estimate is 13 kg. The analysis for the 16.1 km/h test is more complex due to the time dependent dummy orientation. After making estimates of the impact energy using a simple sprung mass model, we back calculated the effective mass assuming the impact energy is equal to the kinetic energy prior to impact (represented by equation 3,

infra

). We also used the sled velocity as a surrogate for relative dummy speed and calculated effective mass directly by using an equation 4,

infra.

From these calculations we estimated a combined head and shoulder effective mass of 22 kg.

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The video from these tests and the data from the dummies, load wall and sled can be accessed from the NHTSA Biomechanics Database at

http://www-nrd.nhtsa.dot.gov/database/aspx/biodb/querytesttable.aspx.

The test numbers are 10282 through 10287. Tests reanalyzed in detail were 10282 (24 km/h test) and 10285 (16.1 km/h test).

In the NPRM preamble, we reported that the agency also performed a computer modeling analysis of an 18 kg impactor and 50th percentile Hybrid III dummy impacting simulated glazing (foam). The comparison found that the total energy transferred by the 18 kg impactor was within the range of the total energy transferred by the entire dummy. For a 16.1 km/h dummy model impact with the foam, the effective mass that came in contact with the foam was between 12.5 kg and 27 kg.

We noted in the NPRM that the 18 kg proposed mass is consistent with that used by General Motors (GM) in 16.2 km/h (10 mph) tests of ejection mitigation curtains.

65

GM based this value on test results from 52 full-vehicle rollover tests that estimated the effective mass of occupant contact with the first row side window area. A more detailed analysis of this study can be found later in this preamble.

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O'Brian-Mitchell, Bridget M., Lange, Robert C., “Ejection Mitigation in Rollover Events—Component Test Development,” SAE 2007-01-0374.

The estimated effective mass for most belted tests was about 5 kg and all were less than 10 kg. The majority of belted tests had effective masses which were a combination of both the near and far side occupants. The effective mass for the unbelted occupants ranged from 5 to 85 kg.

In summary, the proposed impactor mass was based on the determination of an effective mass calculated through both pendulum and sled test impacts and modeling. These methods resulted in a large range of effective mass values. In the end, we deferred to the 18 kg equivalent mass seen during the sled test that was intended to be more representative of a rollover event, which was also the equivalent mass calculated from pendulum impact into the dummy shoulder. For this final rule we have reanalyzed the sled tests and estimated a range of effective mass from approximately 13 to 22 kg. Thus, the 18 kg effective mass is still considered to be a reasonable representation of an occupant's head and a portion of the torso. An effective mass more representative of just the head would be substantially smaller, and an equivalent mass accounting for more torso and lower body mass would be substantially more. The 18 kg mass is well within the GM estimates from vehicle rollover tests, and is consistent with the impactor that GM uses to evaluate side curtains.

2. Comments

There was general support from the vehicle manufacturers and suppliers for using a linear impactor and performance metric based on the displacement of that impactor in a compliance test. There were only a few comments on the impactor dimensions and mass. These few comments were in favor of the proposed mass. While VW and others had comments on the impact energy imparted by the mass, which is an issue which will be addressed in a later section below, VW stated that “the 18 kg mass for the impactor is well established * * *” The Alliance referenced the fact that the GM test procedure for ejection mitigation uses an 18 kg linear impactor in stating that “[t]he Alliance supports the use of the 18 kg headform proposed in the NPRM.”

Some parties commented on the design of the headform. Takata stated that simulated animations have shown relative movement of head skull and headform, and that “the incomplete fixation of the head skull is influencing the displacement behavior of the head form [sic].” Takata suggested enlarging the head skull fixation in the lower portion, by adding a skull cap or enlarging the chin area in the rear for example. Similarly, TRW said that it found that the headform skin can become dislodged from the skull during testing and suggested using a backplate of smaller size on the headform to better clamp the headform skin flange to the skull. TRW also said that the headform skin can become displaced from the lower (chin) area of the skull.

AORC recommended that NHTSA adopt specifications for the skin stiffness, skin friction coefficient, and skull surface finish, to address the headform skin partially dislocating on the headform as a result of friction between the countermeasure and the headform.

TRW suggested changes to the preparation of the headform for testing. It stated that frictional attributes of the headform skin affect the manner in which the headform interacts with the rollover curtain, so talc, chalk, or other coatings could affect test results. TRW suggested that the standard specify that “no coatings shall be applied to the headform skin during testing” and asked, as did AORC, that the standard specify that prior to the test, the headform skin must be cleaned (TRW suggested cleaning the headform with isopropyl alcohol). TRW suggested changes to the headform drawing package to address: The outer surface finish requirements of the skull; the thickness tolerance and durometer hardness of the skin; inner/outer surface finish and tolerance requirements of the skin material type and material properties corridor for the skin; the definition of frictional characteristics of the skin, including the performance corridor; and test procedure and measurement technique for frictional characteristics of skin.

3. Agency Response

We are adopting an 18 kg headform substantially similar to the device described in the NPRM.

We are declining Takata's and TRW's requests to add a skull cap or modify the backplate of the headform. The modification is unnecessary as the new headform has not exhibited the problem these commenters describe. Further, the effect of the modification on actual test results has not been quantified by the commenters. Using modeling, Takata estimated about a 3 mm increase in displacement between the proposed headform and one with the suggested modification, but it is not clear this modeling is representative of an actual impact test.

NHTSA is not inherently opposed to improvements in the headform design to possibly allow for a longer period of head skin use before it needs to be replaced. However, it has not been shown that there is a need to improve the headform at this time. If improvements are feasible and the effect of changing the headform on ejection mitigation countermeasure performance can be better assessed, we are open to considering fine-tuning adjustments to the headform at a future date.

With respect to TRW's comments about the additions and revisions to the drawing package, the NPRM's drawing package already included specifications for the skin material type, thickness and durometer. It also included a specification for preparing the outer surface finish of the skull. TRW did not provide any reason to change these specifications, so they will remain as proposed in the final rule.

We deny TRW's other requests that we specify the inner/outer skin surface finish, skin frictional characteristics, friction performance corridor and friction measurement technique. We do not believe there is a need for these specifications. NHTSA has not before found a need to specify skin surface finish and frictional characteristics for test dummy skin. The commenter provided no justification as to why the material properties provided were insufficient or how the requested parameters would improve the objectivity of the standard.

We are denying the request to place a requirement in the regulatory text to clean the headform skin with isopropyl alcohol as per FMVSS No. 201, “Occupant Protection in Interior Impact.” The commenters provide no data showing the necessity of such provision. FMVSS No. 201 has no requirement that the free motion headform be cleaned with alcohol prior to the testing. There is no FMVSS that specifies in the regulatory text that the dummy skin should be cleaned prior to vehicle testing.

b. Measurement Plane and Displacement Limit (100 mm)

1. NPRM

We proposed that the linear travel of the impactor headform must be limited to 100 mm from the inside of the tested vehicle's glazing as measured with the glazing in an unbroken state. The 100 mm boundary would be first determined with the original glazing “in position” (up) and unbroken. Then, for the test, the original glazing would be in position but pre-broken if it were advanced glazing; or down or removed altogether if it were tempered glazing. It was proposed that advanced glazing would be in position but pre-broken for both the 1.5 second test and the 6-second test.

The NPRM included a window-breaking procedure that damages but does not destroy advanced glazing, while it will obliterate tempered glazing. It was proposed that vehicle manufacturers may remove or completely retract tempered glazing since it would be destroyed in the pre-breaking procedure and would have no effect on the ejection mitigation results. When tested with the original glazing in position but pre-broken or with the glazing removed, the linear travel of the impactor headform must not exceed the 100 mm limit. If a side curtain air bag is present, and we anticipate that most, if not all, vehicles will have an ejection mitigation curtain, the curtain would be deployed.

In the test, the ejection mitigation countermeasure must prevent the headform from exceeding the 100 mm limit. The principle underlying the 100 mm displacement limit is to ensure that the countermeasure does not allow gaps or openings to form through which occupants can be partially or fully ejected. In the research tests, targets that had displacements of less than 100 mm did not allow ejections in dynamic testing.

In research tests, the TRW and Zodiac prototype ejection mitigation countermeasures were tested on a CK

pickup to the proposed impactor test procedure.

66

The TRW prototype had no coverage at position A1 (front window forward lower position). These systems were later tested on the DRF with the 50th percentile male, 5th percentile female and 6-year-old dummies in upright seating positions, and a prone 6-year-old dummy aimed at approximately the target positions A1 and A2 (front window rear lower position). When tested on the DRF, the arms of the upright dummies flailed out of the window opening up to the shoulder at the sill (A1 and A2) and the prone 6-year-old dummy was completely ejected at A1.

66

There were only some slight variations in target locations.

We recognize that dummy ejection did not occur all the time at targets that had displacements of over 100 mm. When tested with pre-broken laminated glazing, at position A1, the TRW system had 181 mm of displacement at the 24 km/h (1.5 second delay) test and 104 mm of displacement in the 20 km/h (1.5 second delay) test, but did not eject either the prone or seated dummies in DRF tests. Nonetheless, the component and DRF testing indicated that there was an increased likelihood that an opening could be formed between the curtain and the window opening through which an occupant could be ejected if the displacement were over 100 mm in the headform test. In addition, a 100-mm limit would also help guard against the countermeasure being overly pliable or elastic so as to allow excessive excursion of an occupant's head and shoulders outside of the confines of the vehicle even in the absence of a gap.

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The agency further notes that an advantage to the displacement limit is that the linear displacement of the headform can be measured in a practicable and relatively straightforward manner, unlike a real-time dynamic measurement of a gap during an impact.

NHTSA also noted in the NPRM that a 100-mm performance limit is used in several regulations relating to occupant retention. In FMVSS No. 217, “Bus emergency exits and window retention and release,” (49 CFR 571.217), bus manufacturers are required to ensure that each piece of glazing and each piece of window frame be retained by its surrounding structure in a manner that prevents the formation of any opening large enough to admit the passage of a 100-mm diameter sphere under a specified force. The purpose of the requirement is to minimize the likelihood of occupants being thrown from the vehicle. This value is also used in FMVSS No. 206, “Door locks and door retention components,” (49 CFR 571.206, as amended 69 FR 75020), to mitigate occupant ejection through unintentional door openings in a crash. In FMVSS No. 206, the door is loaded with 18,000 N of force and the space between the interior of the door and

This text is long and has been trimmed here. Open the source document for the complete record.