# Federal Motor Vehicle Safety Standards, Ejection Mitigation; Phase-In Reporting Requirements

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URL: https://www.frixlaw.com/law-library/documents/fr%3AE9-28177

## Record

- **Collection:** Federal Register
- **Document type:** Proposed Rule
- **Published:** December 2, 2009
- **Citation:** 74 FR 63180

## Text

DEPARTMENT OF TRANSPORTATION
National Highway Traffic Safety Administration
49 CFR Parts 571 and 585
[Docket No. NHTSA-2009-0183]
RIN 2127-AK23
Federal Motor Vehicle Safety Standards, Ejection Mitigation; Phase-In Reporting Requirements

AGENCY:

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

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This notice of proposed rulemaking would establish a new Federal Motor Vehicle Safety Standard (FMVSS) No. 226, to reduce the partial and complete ejection of vehicle occupants through side windows in crashes, particularly rollover crashes. The standard would apply to the side windows next to the first three rows of seats 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 proposing a test in which an impactor would be propelled from inside a test vehicle toward the windows. The ejection mitigation safety system would be 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 would be impacted at up to four locations around its perimeter at two time intervals following deployment.

The agency anticipates that manufacturers would meet the standard by modifying existing side impact air bag curtains, and possibly supplementing them with advanced laminated glazing. The curtains would 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, they would be tethered or otherwise designed to keep the impactor within the vehicle.

This NPRM 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:

You should submit your comments early enough to ensure that the docket receives them not later than February 1, 2010.

ADDRESSES:

You may submit comments (identified by the Docket ID Number above) by any of the following methods:

•
Federal eRulemaking Portal:
Go to
http://www.regulations.gov.
Follow the online instructions for submitting comments.

•
Mail:
Docket Management Facility: U.S. Department of Transportation, 1200 New Jersey Avenue, SE., West Building Ground Floor, Room W12-140, Washington, DC 20590-0001.

•
Hand Delivery or Courier:
West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., between 9 a.m. and 5 p.m. ET, Monday through Friday, except Federal holidays.

•
Fax:
202-493-2251

Instructions:
For detailed instructions on submitting comments and additional information on the rulemaking process, see the Public Participation heading of the Supplementary Information section of this document. Note that all comments received will be posted without change to
http://www.regulations.gov,
including any personal information provided. Please see the Privacy Act heading below.

Privacy Act:
Anyone is able to search the electronic form of all comments 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 (65 FR 19477-78).

Docket:
For access to the docket to read background documents or comments received, go to
http://www.regulations.gov
or the street address listed above. Follow the online instructions for accessing the dockets.

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. Congressional Mandate

III. Safety Problem

IV. Proposed Solution

a. Various Ejection Mitigation Systems Considered

b. Full Window Opening Coverage Is Key

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

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

3. Differences in Design Between the Two Inflatable Systems

4. Insights

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

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

e. Existing Curtains Can Be Made More Effective

1. Existing Curtains

2. Component Tests of Real-World Curtains and Advanced Glazing Systems Show That Improvements Could Be Made

3. Use of Advanced Glazing With the Air Bag Curtain Resulted in Reduced Displacement

4. Field Performance of Ejection Mitigation Curtain Systems

V. Proposed Ejection Mitigation Requirements and Test Procedures

a. Impactor Dimensions and Mass

b. Displacement Limit (100 mm)

c. Speed(s) and Time(s) at Which the Headform Would Impact the Countermeasure.

1. Ejections Can Occur Both Early and Late in the Rollover Event

2. Speed at Which Occupants Impact or Move Through the Window Opening

3. Alternative Testing of Only One Target Position at Higher Speed

d. Locations Where the Device Would Impact the Ejection Mitigation Countermeasure To Assess Efficacy

1. Occupants are Mainly Ejected Through Side Windows

2. The Requirements Would Apply to Side Windows Adjacent to First Three Rows

3. Four Targets Per Glazing Area

4. Method for Determining Impactor Target Locations

e. How Should the Window Glazing Be Positioned or Prepared in the Test To Represent Real-World Circumstances?

1. Window Position and Condition

2. Window Pre-Breaking Specification and Method

f. Test Procedure Tolerances

g. Impactor Test Device Characteristics

h. Readiness Indicator

VI. Other Considered Performance Aspects of an Ejection Mitigation Standard

a. Rollover Sensor

1. Introduction

2. Alternative Approaches

b. Quasi-Static Loading in a Compliance Test

VII. To Which Vehicles Would The Proposed Standard Apply?

VIII. The Proposed Lead Time and Phase-In Schedules

IX. The Estimated Benefits and Costs of This Rulemaking

X. Rulemaking Analyses and Notices

XI. Public Participation

I. Executive Summary

Addressing vehicle rollovers is one of NHTSA's highest safety priorities. In 2002, the agency conducted an in-depth review of rollovers and associated deaths and injuries and assessed how NHTSA 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 researching 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 published a new Federal Motor Vehicle Safety Standard (FMVSS) No. 126 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 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 10,000 lb GVWR have ESC systems, the number of deaths each year resulting from rollover crashes would be reduced by 4,200 to 5,500. Currently, there are over 10,000 such deaths each year.

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. Among the promising technological innovations to prevent occupant ejections are side curtain air bags and improved glazing.

3
The target population addressed by this rulemaking action is discussed in detail in the Preliminary Regulatory Impact Analysis (PRIA) for this NPRM, which has been placed in the docket for this NPRM.

Concurrent with the agency's work on ESC, NHTSA began work on the third initiative on rollover safety, which addresses occupant ejections through side windows in rollovers (“ejection mitigation”). Inroads 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) (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).
4

The pole test, applying to motor vehicles with a GVWR of 4,536 kg (10,000 lb) 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 will install new technologies capable of improving head and thorax protection in side crashes,
i.e.,
side curtain air bags and torso side air bags. We believe that these side curtain air bag systems can be effectively modified to meet the occupant containment requirements of this ejection mitigation initiative on rollover safety.

4
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 § 10302(a).

The ejection mitigation initiative was bolstered by the efforts of vehicle manufacturers to install side impact air bags (SIABs) on a voluntary basis. Immediately prior to the publication of the FMVSS No. 214 NPRM, the Alliance of Automobile Manufacturers (the Alliance), the Association of International Automobile Manufacturers, and the Insurance Institute for Highway Safety announced a voluntary commitment to enhance occupant protection in front-to-side crashes, focusing on, among other things, accelerating the installation of SIABs.
5

The industry's voluntary commitment to install side impact air bags demonstrated the feasibility of installing side curtain air bags on a near fleet-wide basis.

5
See Docket NHTSA-2003-14623-13. Alliance and AIAM members agreed to provide side impact head protection in at least 50 percent of their new passenger car and light truck fleet by September 1, 2007, and in 100 percent of the vehicles by September 1, 2009.

Today's NPRM begins a new stage in implementing ejection mitigation. This document would establish a new FMVSS for ejection mitigation (FMVSS No. 226), specifying occupant containment performance requirements. It would apply to motor vehicles with GVWR of 4,536 kg (10,000 lb) or less. The countermeasures most likely to be installed to meet the performance requirements of this NPRM would be the FMVSS No. 214 side curtain air bags
6

made larger to cover more of the window opening, made 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. We have drafted the test procedure of our proposal to accommodate the use of advanced laminated glazing in fixed and

in possibly moveable windows in addition to or in lieu of the side curtain air bag.

6
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 and is distinct from strictly a “side impact curtain,” which is designed predominately to protect occupants in side crashes and meet the requirements of FMVSS No. 214. Notwithstanding this nomenclature, it is anticipated that rollover curtains will mitigate occupant ejections in side impacts as well as rollover crashes.

The standard would use a guided impactor component test 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 the dynamic rollover event. The impact mass is based on the mass imposed by a 50th percentile male's upper torso on the window opening during an occupant ejection. The mass of the impactor, 18 kilograms (kg) (40 lb), in combination with the impact speed discussed below, has sufficient kinetic energy to assure that the ejection mitigation countermeasure is able to protect a far-reaching population of people in real world crashes. In the test, the linear travel of the impactor beyond where the device contacts the inside of the unbroken vehicle glazing must not exceed 100 millimeters. This displacement limit serves to control the gap size between the countermeasure 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 would typically target four specific locations per side window adjacent to the first three rows of the vehicle. NHTSA has tentatively determined that impacting four targets around the perimeter of the opening would assure that the window will be covered by the curtain, while imposing a reasonable test burden. Small windows would be tested with fewer targets.

Computer modeling has shown that ejections can occur early and late in the rollover event. The impactor would strike the targets at two impact speeds and at two different points in time following side curtain air bag deployment, to ensure that the curtains will retain the occupant from the relatively early through the late stages of a rollover. The first impact would be a 24 kilometer per hour (km/h) (15 miles per hour (mph)) impact, 1.5 seconds after deployment of the curtain. The 1.5 second time delay is proposed because half of all fatal complete ejections occurred in crashes with 5 or more quarter-turns (
1/4
-turns), and film analysis of vehicles that rolled 5 or more
1/4
-turns in staged rollover tests performed by the agency showed the vehicles taking about 1.5 seconds to achieve one complete vehicle revolution. The second impact would be at 16 km/h (10 mph), 6 seconds after deployment of the curtain. Film analysis of the staged vehicle tests showed a maximum roll time of 5.5 seconds for a vehicle that rolled 11
1/4
-turns. The test speeds are representative of the occupant dynamics during the rollover events as well as side impacts. The agency is considering the alternative of applying the 24 km/h (1.5 second delay) impact only to the target location that exhibited the greatest displacement in the 16 km/h (6 second delay) impact.

Under today's NPRM, vehicle manufacturers would have to provide information to NHTSA upon request that describes the conditions under which the ejection mitigation air bags will deploy. We do not believe conditions need to be specified in the standard dictating when the sensors should deploy; field data indicate that rollover sensors are deploying when they should in the real world. We discuss our rationale for this decision in more detail below. Comments are requested on this issue.

II. Congressional Mandate

Section 10301 of SAFETEA-LU required the Secretary to issue by October 1, 2009, an ejection mitigation final rule reducing complete and partial ejections of occupants from outboard seating positions. Section 10301 of SAFETEA-LU amended Subchapter II of chapter 301 (the National Traffic and Motor Vehicle Safety Act, 49 U.S.C. Chapter 301) to add § 30128. 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 gross vehicle weight rating 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. Paragraph (c) states that, in formulating the standards, the Secretary shall consider various ejection mitigation systems, and that the Secretary shall issue a final rule under this paragraph no later than 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 provided appropriate notification to Congress that the final rule will be delayed until January 31, 2011.

III. Safety Problem

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. According to 1998-2007 Fatal Analysis Reporting System (FARS) data, frontal crash fatalities have averaged about 12,000 per year, while rollover fatalities have averaged 10,400 per year. In 2007, 35 percent of all fatalities were in rollover crashes. Since the early 1990s, the sport utility vehicle (SUV) segment has provided an increasing proportion of rollover fatalities. There were approximately 1,700 SUV rollover fatalities in 1998, and more than 2,800 in 2007. 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.
7

7
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 1998-2007 FARS data, about half of the occupants killed in rollovers were completely ejected from their vehicle. During this time period, there were 338 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.
8

Although the majority of occupants exposed to rollover crashes are in vehicles that roll two
1/4
-turns or less, the distribution of ejected occupants who are seriously injured (maximum abbreviated injury scale (MAIS) 3+) or killed is skewed towards rollovers with higher degrees of rotation. According to NASS Crashworthiness Data System (CDS) data of occupants exposed to a rollover crash from 1988 to 2005, half of all fatal complete ejections occurred in crashes with five or more
1/4
-turns.

8
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.

Annualized injury data from 1997 to 2005 NASS CDS and fatality counts adjusted to 2005 FARS levels indicate that ejection through side windows constitutes the greatest part of the ejection problem. There were 6,174 fatalities, 5,271 MAIS 3-5 injuries, and 18,353 MAIS 1-2 injuries for occupants

ejected through side windows. These constitute 61 percent of all ejected fatalities, 47 percent of MAIS 3-5 injuries, and 68 percent of MAIS 1-2 injuries.

This NPRM seeks to reduce complete and partial ejections of occupants from outboard seating positions in crashes involving a rollover or a side planar crash. The target population for this rulemaking would not include the population addressed by the FMVSS No. 214 pole test rulemaking.
9

The target population would also not include persons benefited by the installation of ESC systems in vehicles, based on an assumption that all model year 2011 vehicles would be equipped with ESC. As adjusted, the target population for this ejection mitigation rulemaking is 1,392 fatalities, 1,410 MAIS 3-5 injuries and 4,217 MAIS 1-2 injuries. This target population constitutes 23% of fatally-injured occupants ejected through the side window, 27% of MAIS 3-5 injured, and 23% of MAIS 1-2 injured side window-ejected occupants.

9
The Phase 1 FMVSS No. 214 rulemaking included reduction of partial side window-ejected adult (13+ years) occupants in side impacts, but did not include complete ejections. The Phase 1 rulemaking also excluded any impact where a rollover was the first event. Crashes where a rollover was a subsequent event were included, but only for partially-ejected fatalities. In addition, benefits were only assumed for side impact crashes with 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.

IV. Proposed Solution

a. Various Ejection Mitigation Systems Considered

In formulating this NPRM, NHTSA considered various ejection mitigation systems in accordance with Section 10301 of SAFETEA-LU. One of the considered systems was advanced laminated side glazing, a countermeasure thought in the 1990s to have potential for use in ejection mitigation.
10

In 2002, the agency terminated an advance notice of proposed rulemaking on advanced glazing after observing that advanced glazing appeared to increase the risk of neck injury by producing higher neck shear loads and neck moments than impacts into tempered side glazing (67 FR 41365, June 18, 2002). 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. Moreover, because side curtain air bags were showing potential as an ejection mitigation countermeasure, NHTSA redirected its research and rulemaking efforts toward developing performance-based test procedures for an ejection mitigation standard.
11

10
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.

11
“Ejection Mitigation Using Advanced Glazing, Final Report,” NHTSA, August 2001, DMS Docket 1782-22 (“advance glazing final report”).

As with all of the FMVSSs, this proposed ejection mitigation standard would 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 would likely install ejection mitigation side curtain air bags in response to this rulemaking, taking advantage of the side impact curtains already in vehicles. However, advanced glazing could have a role in complementing ejection mitigation curtain systems. NHTSA tested several vehicles' ejection mitigation side curtain air bags both with and without laminated glazing to the 18 kg impactor performance test proposed in this NPRM. 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 an average 51 mm reduction in impactor displacement across target locations.
12

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, this NPRM proposes to allow windows of advanced laminated glazing to be in position, but pre-broken to reproduce the state of glazing in an actual rollover crash. Although the glazing is pre-broken, the laminate in combination with the remaining integrity of the glazing acts as a barrier to ejection. Details on the pre-breaking method are given later in this preamble. As discussed later, the vast majority of side windows in real-world rollover crashes are closed.
13

12
To accompany this NPRM, NHTSA prepared a technical analysis that presents a detailed analysis of engineering studies, and other information supporting the NPRM, such as the results of NHTSA's impactor testing of OEM and prototype side window ejection mitigation systems, “Technical Analysis in Support of a Notice of Proposed Rulemaking for Ejection Mitigation.” We will refer to this technical analysis from time to time in this preamble. A copy of the technical analysis has been placed in the docket.

13
For the target population of this rulemaking, the front row window through which an occupant was ejected was closed or fixed prior to the crash 69 percent of the time. However, we are concerned that for those instances where manufacturers utilize advanced (laminated) glazing in their design, when the window is partially or fully down, there may be a reduction of occupant retention. As discussed later in this preamble, comments are requested on alternatives to the approach of allowing laminated windows to be in place and pre-broken. One option would be to test with all movable windows removed or rolled down, regardless of whether the window is laminated.

Comments are requested on whether manufacturers would use advanced glazing or some other novel window design alone, without a window curtain, to meet the ejection mitigation requirements throughout the vehicle or at least for some windows (
e.g.,
as the countermeasure to protect against ejection from a small window). Pre-breaking the glazing using the proposed methodology would substantially damage advanced glazing and might foreclose its use to meet the proposed requirements. NHTSA's (limited) test data, discussed below, indicate that various combinations of ejection mitigation countermeasures do not have a high potential for producing neck injury.
14

Yet, in lateral impact tests comparing unbroken advanced glazing alone to tempered glazing, the agency found that in some tests the lateral neck shear forces were higher for the advanced glazing.
15

Given these data, comments are requested on the potential for neck injury in the event that advanced glazing alone were used to comply with the proposed standard.

14
“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.

15
“Ejection Mitigation Using Advanced Glazing, Final Report,”
supra.

b. Full Window Opening Coverage Is Key

NHTSA undertook several research programs using a dynamic rollover fixture (DRF), which produced full-dummy ejection kinematics in an open window condition, to assess the potential effectiveness of ejection mitigation countermeasures in a rollover.
16

These countermeasures

included several designs of inflatable curtain air bags, advanced laminated glazing, and combinations of curtains and advanced glazing. The results showed, however, that not all ejection mitigation air bag curtains work the same way. Full window opening coverage is key to the effectiveness of the curtain in preventing ejection.

16
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 was 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.
17

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.
18

The DRF rotation results in a centripetal acceleration of the dummy that caused it 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 was assessed and compared to that baseline test.

17
“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.

18
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 contact velocity with the side window plane from these two seating positions. From the first position, the impact speeds were 14 km/h (9 mph) for the 5th percentile female dummy and 18 km/h (11 mph) for the 50th male. From the second (inboard) position, the velocities were 31 km/h (19 mph) for the 5th female and 29 km/h (18 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.
19

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.

19
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 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

20

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).

20
HIC
36
is the Head Injury Criterion computed over a 36 msec duration. HIC
36
=1000 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 dummies. The second program investigated whether the gap allowed ejection of the 6-year-old child dummy.
21

21
“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.
22

22
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)
23

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. 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.

23
ITS systems were originally introduced by BMW as a side impact countermeasure.

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. The component-level test is basically the test proposed in this NPRM for ejection mitigation.
24

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
25

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
26

used in agency research has a propulsion mechanism
27

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

24
“Technical Analysis in Support of a Notice of Proposed Rulemaking for Ejection Mitigation,” supra.

25
The “ejection impactor” is the moving mass that strikes the ejection mitigation countermeasure. It consists of an ejection headform attached to a shaft

26
The ejection mitigation test device consists of an ejection impactor and ejection propulsion mechanism.

27
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
1/2
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.

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. The Zodiac system
28

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. 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.

28
Testing was restricted to the extreme corners of the window due to limited availability of this system.

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

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. NHTSA tentatively believes that incorporating the component test into an ejection mitigation standard would ensure 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.
29

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
30

correlated eight different tests to six rollover definitions from NASS-CDS.
31

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.

29
“NHTSA's Crashworthiness Rollover Research Program,”
supra.

30
Viano D, Parenteau C. Rollover Crash Sensing and Safety Overview. SAE 2004-01-0342.

31
“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.
32

NHTSA is concerned that a comprehensive assessment of ejection mitigation countermeasures through full vehicle dynamic testing may only be possible if it were to involve multiple crash scenarios. Such a suite of tests imposes test burdens that could be assuaged by a component test such as that proposed today. We also note that a comprehensive suite of full-vehicle dynamic tests would likely involve many more years of research, which would delay this rulemaking action and the potential for incorporating these life-saving technologies. Such a delay seems unwarranted since NHTSA believes the component test will be an effective means of determining the acceptability of ejection countermeasures. Whether it would be more or less effective than a yet-to-be-defined suite of full vehicle tests remains an open question. However, as explained above, the proposed test clearly has advantages over a single full vehicle test.

32
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.

e. Existing Curtains Can Be Made More Effective

1. Existing Curtains

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 Explorer and Mercury Mountaineer.
33

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

33

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

In addition to 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 for side impact protection. The first difference is longer inflation duration. Rollover crashes with multiple full vehicle rotations can last many seconds. Ford states that its Safety Canopy stays inflated for 6 seconds,
34

while GM has been reported to state that its side curtain air bags designed for rollover protection maintain 80 percent inflation pressure for 5 seconds.
35

Honda reportedly states that the side curtains on the 2005 and later Honda Odyssey stay fully inflated for 3 seconds.
36

(To our knowledge, Ford has not indicated what level of inflation is maintained during the duration.) In contrast, side impact air bag curtains designed for occupant protection in side crashes, generally stay inflated for less than 0.1 seconds.

34

Ibid.

35
“Who Benefits From Side and Head Airbags?” (
http://www.edmunds.com/ownership/safety/articles/105563/article.html
).

36

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

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. Ford reportedly stated that its rollover protection air bags cover 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.
37

GM reportedly stated that its curtains designed for rollover protection are larger than non-rollover curtains.
38

37

Ibid.

38
Who Benefits From Side and Head Airbags?” (
http://www.edmunds.com/ownership/safety/articles/105563/article.html
).

2. Component Tests of Real-World Curtains and Advanced Glazing Systems Show That Improvements Could Be Made

NHTSA has tested real-world side window air bag curtains and advanced glazing
39

according to the test procedure proposed in this NPRM, except for some differences in the target locations.
40 41

In addition, prototype Zodiac and TRW systems were installed on the GM CK pickup and the Lincoln Navigator. In this section of the preamble, we provide test results for ejection mitigation countermeasures installed as original equipment (OE) and as prototypes, tested to the proposed requirements. One of the findings of this test series was that none of the original equipment (OE) systems met the proposed displacement limit when impacted at the target in the forward lower corner of the front window (target A1, see Figure 1 below) at 24 km/h.
42

39
The laminates tested were marketed as theft protection and not as a form of ejection mitigation.

40
“Status of NHTSA's Ejection Mitigation Research Program,”
supra.

41
“NHTSA Crashworthiness Rollover Research Program,”
supra.

42
“Technical Analysis in Support of a Notice of Proposed Rulemaking for Ejection Mitigation,”
supra.

The target locations shown in Figure 1 were determined by the method proposed for this NPRM. With the exception of the Honda Odyssey, for all tests of prototype systems and OE system through MY05, the method for determining the target location was slightly different than currently proposed. (We will refer to this method as the “research target method” as opposed to the “proposed target method.”) The MY05 Odyssey was tested by the proposed target method. As explained below, the differences in target locations identified by the two methods are small enough that data using the research target method can be reasonably compared to the proposed target method.

The difference in determining the target location had the most effect on the location of A2, A3, B1 and B4. The resulting shift in target location was a function of the window shape. The primary difference in the research target method was that A3 was found by bisecting the angle produced by the intersection of a line parallel to the A-pillar and roof rail, which in the case of the window in Figure 1 would shift A3 rearward and upward. Since A2 is located horizontally midway between A3 and A4 in both the research and proposed target methods, A2 in the research target method would be rearward of the A2 position shown in Figure 1.

The rear window data for prototype and OE system through MY05 is, for the most part, limited to B1 and B4. Under the research target method used to find the target locations, B1 was at the lower sill, in the middle of the window and B4 was in the upper rear corner. Again, under the research target method, B1 and B4 would likely be shifted forward from the location shown in Figure 1. For the test of the Zodiac prototype on the Navigator, extra targets were impacted. For only this vehicle, Tables 1 through 3 of this preamble present an average

result from two impacts that were on either side of the proposed targets B1 and B4.

EP02DE09.000

The results of the testing are given in Tables 1 through 3. The results are given in columns, by target location. These data are also found in a color coded format in the Technical Analysis report accompanying this NPRM. The target location key is shown in Figure 1 of this preamble, supra. In general, for a particular vehicle and target location, if multiple trials were run at a particular impact speed and time delay, each of the displacement results is shown by separating the table cell into two or three cells.

Although the agency is proposing a 24 km/h impact test 1.5 seconds after air bag deployment, research data was acquired at 20 km/h to determine the sensitivity to impact speed. Several ejection mitigation systems were not tested at 24 km/h at every target location because the 20 km/h results indicated displacements in excess of 100 mm at that location. We assume the 24 km/h impact would also have exceeded 100 mm. Where this occurred, the cell in Table 1 contains the 20 km/h displacement value and is identified by an asterisk. Similarly, some target locations were not tested at 20 km/h, but we assume that the value that would have been obtained would be below 80 mm of displacement because the 24 km/h impact was less than 80 mm. Where this occurred, the cell in Table 2 contains the 24 km/h displacement value and is identified by a double asterisk.

Tables 1 through 3 show the results for vehicle front windows. For all three sets of tests, A1 was the most challenging target and A4 was the least challenging. For the 24 km/h test, the only system that did not exceed the 100 mm criterion at A1 was the Zodiac prototype on the CK pickup. At 20 km/h, the MY05 Infinity had one test result of 99 mm and another of 106 mm at A1. For the 16 km/h impact at a 1.5 second delay, two OE systems and two prototype systems had displacements slightly more or less than 100 mm at A1. No displacement at A4 exceeded 76, 73 or 67 mm at 24, 20 and 16 km/h, respectively. Taken as a whole, A2 and A3 showed similar results to each other for all three test conditions in that neither was as consistently challenging to meet as A1 nor as easily met as A4. The trends for severity by target location are the same for the 16 km/h impacts at a 6 second delay.

Table 1—Impactor Displacement—Front Row Window, 24 km/h Impact, 1.5 Second Delay

Position
A1

Position
A2

Position
A3

Position
A4

03 Navigator
No Data
* 186 196*
* 229
−22.

03 Navigator w/lam
No Data
35
No Data
No Data.

04 Volvo XC90
* 163
193
130
18.

04 Volvo w/lam
* 102 * 151
44
118
15.

05 Nissan Pathfinder
* 181
161
* 240
76 76.

05 Toyota Highlander
* 159 * 164
202
137
67.

05 Infinity FX35
124
83 96 112
89 89 108
53.

05 Chevy Trailblazer
138
168
159
No Data.

05 Chevy Trailblazer w/lam
No Data
No Data
* 107 * 110
No Data.

05 Honda Odyssey
No Cover
119
107
No Data.

06 Dodge Durango
174
156
* 180
54.

06 Dodge Durango w/lam
No Data
* 101
No Data
No Data.

Zodiac Prot. on CK
12
19
No Data
No Data.

Zodiac Prot. on Navigator
150 143
54
96 102
21 24.

Zodiac Prot. on Nav. w/lam
No Data
No Data
91 97
No Data.

TRW Prot. on CK

No Cover
†

82 82 102
2 6
−13 −8.

TRW Prot. on CK w/lam
180 182
21
−26 −26
−33 −25.

* Only tested at 20 km/h and displacement exceeded 100 mm.

†
No countermeasure at this target location.

Table 2—Impactor Displacement—Front Row Window, 20 km/h Impact, 1.5 Second Delay

Position
A1

Position
A2

Position
A3

Position
A4

03 Navigator
No Data
186 196
229
−37.

03 Navigator w/theft lam
No Data
6
No Data
No Data.

04 Volvo XC90
163
84 107
107 131
−3.

04 Volvo w/theft lam
102 151
27
97
** 15.

05 Nissan Pathfinder
181
133
240
58

05 Toyota Highlander
159 164
113 150
106 113
73.

05 Infinity FX35
99 106
58
70
29.

05 Chevy Trailblazer
112
121
127
No Data.

05 Chevy Trailblazer w/lam
90
80
109
No Data.

05 Honda Odyssey

No Cover
†

96
57
−45.

06 Dodge Durango
160
140
180
18.

06 Dodge Durango w/lam
No Data
101
No Data
No Data.

Zodiac Prot. on CK
−12
−9
No Data
No Data.

Zodiac Prot. on Navigator
122
38
76 81
−9 −0.9.

Zodiac Prot. on Nav. w/lam
No Data
No Data
No Data
No Data.

TRW Prot. on CK

No Cover
†

75
−29
−52.

TRW Prot. on CK w/lam
104
0
−54
−60 −63.

** Only tested at 24 km/h and displacement was below 80 mm.

†
No countermeasure at this target location.

Table 3—Impactor Displacement—Front Row Window, 16 km/h Impact, 6 Second Delay

Position A1
Position A2
Position A3
Position A4

03 Navigator
243
74
211
−30.

03 Navigator w/theft lam
157
−14
137
No Data.

04 Volvo XC90
154 167
52 93
78
−22.

04 Volvo w/theft lam
86 105
26
59
No Data.

05 Nissan Pathfinder
108 120
93 106
188
37 46.

05 Toyota Highlander
198
132
147
67.

05 Infinity FX35
85
21
39
9.

05 Chevy Trailblazer
121
192
124
No Data.

05 Chevy Trailblazer w/lam
No Data
102
No Data
No Data.

05 Honda Odyssey

No Cover
†

77
47 90
−54.

06 Dodge Durango
138
135
167
13.

06 Dodge Durango w/lam
No Data
No Data
142
No Data.

Zodiac Prot. on CK
0
0
No Data
No Data.

Zodiac Prot. on Navigator
135
49
78 81
−0.2.

Zodiac Prot. on Nav. w/lam
104
No Data
70
No Data.

TRW Prot. on CK

No Cover
†

99 97
−36
−41.

TRW Prot. On CK w/lam
80
−3
−44
−67.

†
No countermeasure at this target location.

The 2nd row window data in Tables 4 through 6 are much more limited, with nearly all the data at B1 and B4. In general, these data indicate target location B1 is more challenging than B4. The exception to this is the Dodge Durango, which performed well at all 2nd row targets. For the 24 km/h test at B1, three of the ejection mitigation systems tested had displacements that did not exceed 100 mm. For the 20 and 16 km/h test at B1, a total of 3 systems did not exceed 100 mm. We also expect that the Durango would not have exceeded 100 mm at 20 km/h, since it did not exceed 100 mm at 24 km/h. At B4, three systems had displacements that exceeded 100 mm. This was reduced to one system for the 20 and 16 km/h impacts.

Any cell listed as “To Stops” indicates a displacement of the impactor to the point where the mechanical stops of the device keep it from further movement. This occurred for the MY03 Navigator at B1 at 24 and 20 km/h. “To stops” is considered an infinite displacement and indicates very little countermeasure coverage at this location.

Table 7 shows very limited 3rd row window data for the Odyssey and Durango at all test conditions. For this system C4 is much more challenging than C1.
43

43
We are using C1 through C4 to denote the impact locations for the 3rd row window. Third row target locations were found in the same manner as 2nd row targets.

Table 4—Second Row Window, 24 km/h Impact, 1.5 Second Delay

Position B1
Position B2
Position B3
Position B4

03 Navigator
To Stops
No Data
No Data
−40.

04 Volvo XC90

(20 km/h)
*

No Data
No Data
69.

04 Volvo w/theft lam
91/93
No Data
No Data
62.

05 Nissan Pathfinder
161
No Data
No Data
128.

05 Toyota Highlander
146
No Data
No Data
149.

05 Infinity FX35
143
No Data
No Data
45.

05 Honda Odyssey
71
152
80
193.

06 Dodge Durango
76
86
91
82.

Zodiac Prot. on Navigator

Avg. = 98

(96 to 100)
‡
.

99
No Data

Avg. = 104 (32 to 176)
‡
.

* Exceeded 100 mm at 20 km/h.

‡
Combines data from two impact location closest to the defined target location.

Table 5—Second Row Window, 20 km/h Impact, 1.5 Second Delay

Position B1
Position B2
Position B3
Position B4

03 Navigator
To Stops
No Data
No Data
−14.

04 Volvo XC90
183
No Data
No Data
(24 km/h) **.

04 Volvo w/theft lam
94
No Data
No Data
(24 km/h) **.

05 Nissan Pathfinder
126/150
No Data
No Data
99.

05 Toyota Highlander
107
No Data
No Data
102.

05 Infinity FX35
79 94
No Data
No Data
21.

05 Honda Odyssey
42
134
34
84.

06 Dodge Durango
(24 km/h)
No Data
No Data
No Data.

Zodiac Prot. on Navigator

Avg. = 70

(67 to 72)
‡
.

70
No Data

Avg. = 77 (9 to 144)
‡
.

‡
Combines data from two impact location closest to the defined target location.

**
Below 80 mm at 24 km/h.

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

Position B1
Position B2
Position B3
Position B4

03 Navigator
126
No Data
No Data
−27.

04 Volvo XC90
189
No Data
No Data
29.

04 Volvo w/theft lam
63
No Data
No Data
9.

05 Nissan Pathfinder
104
No Data
No Data
75.

05 Toyota Highlander
138
No Data
No Data
107.

05 Infinity FX35
61
No Data
No Data
19.

05 Honda Odyssey
12
121
55
28.

06 Dodge Durango
3
36
71
18.

Zodiac Prot. on Navigator

Avg. = 81 (73 to 89)
†

98
No Data

Avg. = 67 (16 to 117)
†
.

†
Combines data from two impact location closest to the defined target location.

Table 7—Third Row Window, All Impact Speeds and Time Delays

Position C1
Position C2
Position C3
Position C4

24 km/h—1.5 s

05 Honda Odyssey
No Data
No Data
175
(20 km/h) *.

06 Dodge Durango
No Data
No Data
No Data
(20 km/h) *.

20 km/h—1.5 s

05 Honda Odyssey
58
No Data
122
To Stops.

06 Dodge Durango
66
No Data
No Data
283.

16 km/h—6 s

05 Honda Odyssey
44
To Stops
80
331.

06 Dodge Durango
52
No Data
No Data
No Data.

* Exceeded 100 mm at 20 km/h.

Summarized below are some very general trends for the displacement data. These trends were based on limited data and were not analyzed for statistical significance.

Within target locations we found the following general trends:

• The 24 km/h—1.5 second delay test was the most challenging test;

• The 20 km/h—1.5 second test was more consistently challenging than the 16 km/h—6 second test;

• For the 24 km/h test, the only system that did not exceed the 100 mm criterion at A1 was the Zodiac Prototype on the CK pickup.

Comparing target locations we found the following general trends:

• In row one, A1 was the most consistently challenging target and A4 was the least;

• In row two, target location B1 was more consistently challenging than target B4;

• Data from the third row targets were too limited to indicate any trends.

3. Use of advanced glazing with the air bag curtain resulted in reduced displacement

Several vehicles were tested both with and without laminated glazing. A prototype glazing was used on the CK pickup. Tests where advanced glazing was used resulted in a reduction in impactor displacement. Table 8 shows the reduction in impactor displacement for each of the vehicles. Not every target location was tested at each impact speed. For all prototype and MY06 and older vehicles, the glazing was pre-broken using a ball-peen hammer method discussed in the Technical Analysis report accompanying this NPRM, while for MY07 vehicles, the glazing was broken using a 50 mm matrix hole punch pattern. (The agency is proposing the latter method in this NPRM.)

The largest displacement reduction was for the MY03 Navigator at A2, impacted at 20 km/h—1.5 second delay. This location exhibited a 185 mm change in displacement (from 191 mm to 6 mm). The smallest change in displacement was 3 mm (18 mm to 15 mm) for the MY04 XC90 at A4, impacted at 24 km/h—1.5 second delay. For target positions with multiple vehicle tests, the A2 position had the largest change in displacement at each test speed. The average displacement reduction across target locations and test types was 51 mm.

Table 8—Reduction in Impactor Displacement Resulting From Pre-Broken Laminated Glazing

A1
A2
A3
A4
B1
B4

24 km/h, 1.5 sec.:

04 Volvo XC90

149
12
3

7

Zodiac Prot. on Navigator

5

TRW Prot. on CK

68
30
19

Average

108
16
11

20 km/h, 1.5 sec.:

03 Navigator

185

04 Volvo XC90
37
69
22

89

05 Trailblazer
22
41
19

06 Durango

47

TRW Prot. on CK

75
25
10

Average
29
83
22

16 km/h, 6 sec.:

03 Navigator
86
88
74

04 Volvo XC90
65
47
19

126
20

05 Trailblazer

90

06 Durango

25

07 Commander

91

Zodiac Prot. on Navigator
31

10

TRW Prot. on CK

101
8
26

Average
61
83
27

4. Field Performance of Ejection Mitigation Curtain Systems

To better understand the field performance of the current fleet equipped with rollover systems, the agency evaluated available crash data. 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. The available data reviewed included a detailed analysis of a very limited number of rollover crashes by NHTSA's Special Crash Investigation (SCI) division. In all of the cases, the ejection countermeasure in the vehicle was an air bag curtain which partially covered the first two window rows.

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 agreed to notify SCI of the crashes.) The subject vehicles were Ford Expeditions, a Ford Explorer, a Mercury Mountaineer, and a Volvo XC90. Table 9 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 9—Ford SCI Rollover Cases

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).

V. Proposed Ejection Mitigation Requirements and Test Procedures

As discussed above, NHTSA's research on rollover ejection found that with partial window opening coverage by a curtain, occupants initially contacting covered areas can slide to an opening and be ejected. The agency is proposing a test that requires ejection mitigation curtains to retain an impactor such that its displacement is limited to a specified distance outside of the window. To assure full window opening coverage through the duration of a rollover, the proposed test procedure would require the first three rows of side window openings to be impacted at up to four locations around the perimeter of the opening at two time intervals.

In this section, we discuss in detail the rationale for selection of the impactor test parameters. The primary parameters that determine the stringency of the test are: (a) The impactor dimensions and mass; (b) the displacement limit; (c) impactor speed and time of impact; and (d) target locations. We also discuss: (e) glazing issues; (f) test procedure tolerances; (g) test device characteristics; and (h) a proposal for a telltale requirement. See also “Technical Analysis in Support of a Notice of Proposed Rulemaking for Ejection Mitigation,” supra.

a. Impactor Dimensions and Mass

The component test involves use of a guided linear impactor 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).
44

It averages the dimensional and inertial characteristics of the frontal and lateral regions of the head into a single headform. The headform is covered with an approximately 10 mm thick dummy skin material whose outer surface dimensions are given in Figure 2, below. The Technical Analysis report discusses other dimensional attributes of the headform, such as the curvature of the outer surface. There are many possible ways of delivering the impactor to the target location on the ejection mitigation countermeasure. The impactor used in agency research propels the shaft component of the impactor with a pneumatic piston. The shaft slides along a plastic (polyethylene) bearing. The impactor has an 18 kg mass.
45

44
“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.

45
Since the proposed 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 appears to be 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.

EP02DE09.001

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”).
46

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) currently used for FMVSS No. 214, “Side impact protection,” does not have. A linear impact pendulum weighing 23.4 kg (51.5 lb) 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, to replicate advanced glazing impacts.

46
“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 representative of a rollover event and the second of a side impact event.

In the rollover condition, the impact speed was 16.1 km/h 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 24 km/h. 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 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 the 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 determined that early in each event, when the impacting mass is traveling near the pre-impact velocity, the energy levels of a 9 kg mass traveling at 24 km/h [9 kg × (6.67 m/s)
2
/2 = 200 Nm] and an 18 kg mass traveling at 16 km/h [18 kg × (4.47 m/s)
2
/2 = 180 Nm] were roughly the same. In consideration of the similarity of energy results for the sled testing at two impact speeds, 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.

The final part of the analysis involved computer modeling 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 note that the 18 kg proposed mass is consistent with that used by General Motors (GM) in 16.2 km/h (4.5 m/s) tests of ejection mitigation curtains.
47

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. Forty-six percent of the tests were less than a
1/4
-turn, 27 percent were one
1/4
-turn and 27 percent were two
1/4
-turns. (Twenty of the rollovers were curb trip; 18 were soil trip; 11 were fall-over, and 3 were corkscrew.) The tests used two 50th percentile male Hybrid III dummies in the front seats. In half of the tests, the dummies were belted and in half they were not. A membrane was placed over the window area to prevent ejections, and tri-axial load cells were incorporated into the membrane at the corners of the window opening. The effective mass was calculated using the resultant loading on the dummy head by the window membrane, along with resultant head and chest accelerations.

47
O'Brian-Mitchell, Bridget M., Lange, Robert C., “Ejection Mitigation in Rollover Events—Component Test Development,” SAE 2007-01-0374.

For a subset of tests the effective mass was calculated using the impulse and momentum principle represented by:

∫ Fdt = mΔv

Where:

F = membrane contact force

m = effective mass

Δv = change in occupant velocity

Results were similar for tests employing both methods. 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. However, we note there was a 40 kg effective mass for a single unbelted occupant contact. Energy levels calculated by using effective mass and peak head velocity were all below 182.25 Nm. This is the amount of energy imparted in GM's internal impactor testing (18 kg impactor and a 16.2 km/h (4.5 m/s) velocity).

Request for Comments on the Impactor

In summary, the impactor mass was based on the determination of an effective mass calculated through both pendulum and sled test impacts. Sled tests designed to represent both side impacts and rollover impacts gave similar energies and two equivalent mass estimates. The 18 kg equivalent mass was seen during the test intended to be more representative of a rollover event. This was also the equivalent mass calculated from pendulum impact into the dummy shoulder. Thus, the 18 kg equivalent mass is considered a reasonable representation of an occupant's head and a portion of the torso. An equivalent 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 effective mass GM estimates from vehicle rollover tests, and is consistent with the impactor that GM uses to evaluate side curtains. Comments are requested on the 18 kg mass for the linear impactor headform.

b. Displacement Limit (100 mm)

We are proposing 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 either: (a) In position but pre-broken; or (b) removed altogether, at the manufacturer's option.

The window-breaking procedure will damage but not destroy advanced (laminated) glazing, while it will obliterate tempered glazing. For vehicles with advanced glazing, the damaged glazing would be permitted to be in position under option (a), above. Tempered glazing will disintegrate when subjected to the window-breaking procedure, so under option (b), above, manufacturers may remove or completely retract the window 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 (curtain) does not allow gaps or openings to form through which occupants can be ejected. In the component test results, targets that had displacements of less than 100 mm did not eject the dummy in dynamic testing. As discussed previously in this preamble, the TRW and Zodiac prototype ejection mitigation countermeasures were tested on a CK pickup to the proposed impactor test procedure.
48

The TRW prototype had no coverage at position A1 (front window forward lower position), so the displacement in the impactor test was unlimited for all impact speeds and time delays (displacements well over 100 mm at position A1). 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.

48
There were only some slight variations in target locations.

It is noted, however, 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 a 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 indicate that there is an increased likelihood that a gap 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.

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). In FMVSS No. 206, the door is loaded with 18,000 N and the space between the interior of the door and the exterior of the door frame must be less than 100 mm. In addition, NHTSA also considered that a value of approximately 100 mm is used by the International Code Council (ICC) in developing building codes used to construct residential and commercial buildings.
49

The ICC 2006 International Building Code and 2006 International Residential Code require guards to be placed around areas such as open-sided walking areas, stairs, ramps, balconies and landings. The guards must not allow passage of a sphere 4 inches (102 mm) in diameter up to a height of 34 inches (864 mm). The ICC explains in the Commentary accompanying the Codes that the 4-inch spacing was chosen after considering information showing that the 4-inch opening will prevent nearly all children 1 year in age or older from falling through the guard.

49
The ICC is a nonprofit membership association that works on developing a single set of comprehensive and coordinated national model construction codes.
http://www.iccsafe.org/news/about/.

Request for Comments on the Displacement Limit

NHTSA requests comment on the linear displacement limit of 100 mm as an appropriate value. We note that GM developed a test procedure that also uses a 100 mm displacement limit,
50

but the zero displacement plane is defined in a slightly different way. GM places a plane tangent to the exterior of the side of the vehicle at the target location and defines the displacement perpendicular to this excursion plane. Thus, the allowable GM displacement would be approximately 100/cos(θ) mm if other aspects of the test were identical to those of today's NPRM, with θ being the angle with the vertical of the exterior plane. If θ were 20 degrees, the GM limit would be approximately 106 mm, which allows slightly more displacement than the 100 mm proposal. The GM method also results in a slightly different allowable final displacement position than the proposed method because of the separation between the flat excursion plane and the inside surface of the window at the target location.
51

We do not know how that difference affects the final allowable displacement of the headform.

50
O'Brian-Mitchell, Bridget M., Lange, Robert C., “Ejection Mitigation in Rollover Events—Component Test Development,” SAE 2007-01-0374.

51
GM explained that their justification for the 100 mm displacement limit is that it represents half the height of the 50th percentile male Hybrid III head.

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. The latter would likely involve complex and multiple imaging systems. Comments are requested on this issue.

c. Speed(s) and Time(s) at Which the Headform Would Impact the Countermeasure

As will be discussed in this section, there appears to be a need for a relatively high speed impact shortly after countermeasure deployment and a lower speed impact late in the deployment. The two time delays correspond to relatively early and late times in a rollover event.
52

The first impact would be at 24 km/h, and at 1.5 seconds after countermeasure deployment (1.5 second time delay). The second impact would be a 16 km/h impact initiated 6 seconds after deployment.

52
Each impact would take place on a test specimen (
e.g.
, a curtain) that was not previously subject to an impact test.

We are proposing and requesting comments on two alternatives regarding the testing of the four target locations for each window opening (see subsection 4, below). Only one of the alternatives would be selected for the final rule. The first proposal would subject all four target locations to both the 16 km/h (6 second time delay) and the 24 km/h (1.5 second time delay) impacts (which would amount to eight impacts per window). The second proposal would be to apply the 16 km/h (6 second time delay) test on all four target locations but just apply the 24 km/h (1.5 second time delay) test to the location that had the greatest displacement in the 16 km/h (6 second time delay) test (which would amount to five impacts per window). The second approach would reduce the costs and burdens of the impact tests per vehicle.

1. Ejections Can Occur Both Early and Late in the Rollover Event

Two impacts are proposed because ejections can occur both early and late in the rollover event. In the advanced glazing program, NHTSA performed a series of simulations to recreate three NASS-investigated rollover crashes with ejected occupants.
53

The vehicles were a MY 1991 Toyota pickup, a MY 1986 Toyota Corolla and a MY 1985 Volkswagen Jetta.
54

Vehicle handling simulation software
55

reconstructed the vehicle motion up to the point where the vehicle started to roll. The linear and angular velocity at the end of the vehicle handling simulation was then used as input to a MADYMO
56

lumped parameter model of the vehicle to compute its complete rollover motion. The motion of the vehicle obtained from the MADYMO vehicle model was used as input to a MADYMO occupant simulation. Head and torso velocities of a Hybrid III 50th percentile male driver dummy were calculated for the three rollover simulations.

53
“Ejection Mitigation Using Advanced Glazings: A Status Report,” November 1995, Docket NHTSA-1996-1782-3. Pg. 6-1.

54
The circumstances of the Toyota pickup rollover were that the vehicle was traveling at 96 km/h and went into a sharp turn and yaw, which resulted in a rollover. In the case of the Corolla, it was also traveling 96 km/h on a gravel road. The vehicle went out of control and left the road, resulting in roll initiation. The Volkswagen was traveling at 88 km/h when the driver fell asleep and the vehicle left the road. It struck a rock embankment and rolled over.

55
VDANL software user's manual V2.34, STI, 1992.

56
MADYMO user's manual V5.1, TNO, 1994.

Table 10 shows the simulation resultant head velocity through the open window at the time of ejection. As indicated in the table, the occupant of the pickup was ejected early (1st
1/4
-turn for Toyota truck) while the occupants of the other vehicles were ejected late (last
1/4
-turn for Corolla and Jetta) in the rollover event.

Table 10—Head and Torso Velocities of a Hybrid III 50th Percentile Male Dummy in 3 Rollover Simulations

Vehicle

Vehicle
1/4
turns

1/4
Turns at
complete ejection

Restraint use
Head to opening (km/h)
Head to glazing (km/h)
Torso to glazing (km/h)

Toyota PU
12

Yes
20
20
7

1
No
5
20
16

Toyota Corolla (86)
6

Yes
15
15
11

6
No
13
13
10

Volkswagen Jetta (85)
4

Yes
14
14
10

4
No
22
18
16

The agency has also considered other data indicating that very early occupant contact with the window area is possible in rollover crashes. Table 11 gives information on 30 rollover tests the agency performed from the mid-1980s to the mid-1990s. This data set included Rollover Test Device (RTD) tests, FMVSS No. 208 dolly tests, guardrail tests and pole tests.
57

A film analysis of dummy motion within the vehicles showed that, excluding a pole impact test, occupant contact with the window opening and surrounding area first occurred between 0.16 and 0.88 seconds after the event began.
58

We note, however, that the majority of these dummies were belted, which means they would be most representative of potential partial ejections. In addition, where the time of window breaking is known, most of these first contacts occurred prior to the window breaking due to roof contact.

57
These tests were done as part of a research program evaluating full scale dynamic rollover test methods, occupant kinematics, and vehicle responses. The RTD tests were similar to the FMVSS No. 208 dolly test except that the vehicle was initially 4 feet off of the ground instead of 9 inches, and hydraulic cylinders were used to push the vehicle from the cart and produce an initial roll rate. The guardrail tests used a guardrail as a ramp to initiate a vehicle roll. The pole tests rolled a vehicle into a pole. Twenty-four of these were RTD tests on passenger cars, pickups and vans (the RTD testing was not geared towards ejection testing since all of the test dummies were belted), and four were FMVSS No. 208 dolly tests on Ford Explorers. The test films are available at the National Crash Analysis Center (NCAC) at George Washington University
(http://www.ncac.gwu.edu
).

58
“Evaluation of Full Vehicle Rollover Films,” 2008, Docket NHTSA-2006-26467.

Table 11—NHTSA Full Vehicle Rollover Testing Film Analysis

Test No.
Make
Model
MY
Test type

Tilt angle
(deg.)

Roll axis
(deg.)

Vehicle speed
(km/h)

1/4
-Turns

Total time
(sec)

878
Honda
Accord
84
RTD
41
45
33.8
2
1.29

888
Chevrolet
Celebrity
82
RTD
41
45
37.0
4
3.58

920
Dodge
Omni
79
RTD
41
45
37.0
2
0.96

939
Mercury
Zephyr
82
RTD
41
60
37.0
2
2.08

1255
Ford
Bronco
88
RTD
30
45
37.0
2
1.17

1266
Dodge
Caravan
88
RTD
30
45
48.3
1
0.50

1267
Chevrolet
Pickup
88
RTD
30
45
48.3
4
2.58

1274
Nissan
Pickup
88
RTD
30
45
48.3
6
3.76

1289
Nissan
Pickup
89
RTD
30
45
48.3
2
0.83

1391
Dodge
Caravan
89
RTD
30
45
48.3
8
5.08

1392
Ford
Bronco
89
RTD
30
0
48.3
8
3.60

1393
Nissan
Pickup
89
RTD
30
0
48.3
4
2.35

1394
Nissan
Pickup
89
RTD
30
0
48.3
4
1.33

1395
Pontiac
Grand Am
89
RTD
30
0
48.3
2
1.54

1471
Dodge
Colt
89
RTD
30
90
48.3
2
0.99

1520
Ford
Ranger
88
RTD
30
0
48.3
2
0.75

1521
Dodge
Ram
88
RTD
30
0
48.3
4
1.42

1530
Dodge
Caravan
88
Guardrail
N/A
N/A
96.6
1
N/A

1531
Nissan
Pickup
88
Guardrail
N/A
N/A
96.6
4
N/A

1546
Plymouth
Reliant
81
RTD
41
45
33.8
6
3.00

1851
Volvo
240
91
RTD
30
0
48.3
6
2.50

1852
Volvo
740
91
RTD
30
0
48.3
8
3.00

1925
Nissan
Pickup
90
RTD
30
0
48.3
8
3.04

1929
Nissan
Pickup
90
RTD
30
0
48.3
6
2.25

2141
Nissan
Pickup
90
RTD
30
0
48.3
8
4.25

2270
Nissan
Pickup
89
RTD
30
0
48.3
8
3.50

2514
Ford
Explorer
94
208
23
0
48.3
11
5.50

2553
Ford
Explorer
93
208
23
0
48.3
10
N/A

3012
Ford
Explorer
94
208
23
0
48.3
11
N/A

3635
Ford
Explorer
94
208
23
0
48.3
12
5.17

Analysis of 5+
1/4
-turn Tests

Average

47.2
8.3
3.7

Maximum

96.6
12
5.5

Average + 2 standard deviations

55.2
12.3
5.8

The agency is proposing that the ejection mitigation countermeasure be first tested at 1.5 seconds after deployment of the ejection countermeasure. As indicated earlier in this preamble, more than half of the

complete ejection fatalities occur when the vehicle rolls 5+
1/4
-turns. As shown in Table 11, restricting the analysis to the tests with 5+
1/4
-turns, the average amount of time to complete 1 full vehicle revolution (4
1/4
-turns) was 1.62 seconds with a standard deviation of 0.31 seconds. Thus, the 1.5 second represents a period of time in which one full vehicle revolution occurs in a high-energy rollover event. We also note that at 1.5 seconds into the rollover, roof contact would likely have occurred, leading to window breaking. Thus, as discussed at section V(e) of this preamble, we are proposing to pre-break the glazing prior to this test.

Additional rationale comes from data obtained from the advanced glazing program (see Table 12, infra). In that program, NHTSA tested vehicles on the DRF with 5th percentile adult female and 50th percentile adult male test dummies (near and far side).
59

Video analysis of dummy head impact velocities with the glazing showed that for the 5th percentile female far side occupant, the time to glazing impact after the DRF began rotating was between 1.3 and 1.8 seconds, which was in the range of two to three
1/4
-turns of rotation. The peak impact speed was 31 km/h. Table 12 shows the estimated velocities for the near and far side dummies.

59
Duffy, S., “Test Procedure for Evaluating Ejection Mitigation Systems,” 2002 SAE Government/Industry Meeting.

Table 12—DRF Testing Results

Dummy

Impact speed
(km/h)

Near side
Far side

Far side impact
time
(sec.)

Far side impact

1/4
turns

5th Female
14
31
1.3-1.8
2-3

50th Male
18
29

The agency is also proposing that ejection mitigation countermeasures be tested towards the end of a rollover. Data indicate that occupants could impact the window opening as late as 6 seconds after initiation of a rollover involving 5+
1/4
-turns. The last three rows of Table 11, supra, show the average and maximum number of
1/4
-turns and the total time of rollovers involving 5+
1/4
-turns.
60

This set of data contains 14 tests (highlighted in table). The average and maximum number of
1/4
-turns are 8.3 and 12, respectively. The average plus two standard deviations is 12.3 turns. Thus, 12.3
1/4
-turns is the 98th percentile value for this subset of data. The average and maximum times to complete the entire rollover event were 3.7 and 5.5 seconds, respectively. The 98th percentile value was 5.8 seconds, which is not much different than the maximum time for the entire data set, which was 5.5 seconds.

60
As earlier, more than half of the complete ejection fatalities occur when the vehicle rolls 5+
1/4
-turns.

Other information we considered also supported a 6-second impact time. The data set provided in Table 11,
supra,
showed the vehicle with the longest rollover time (5.5 seconds) in the FMVSS No. 208 dolly test rolled eleven
1/4
-turns. NASS-CDS shows that rollovers with eleven
1/4
-turns account for about 90% of rollovers with fatal complete ejection,
i.e.,
10% of rollovers with fatal complete ejections have more than eleven
1/4
-turns. This does not mean that rollover crashes with eleven
1/4
-turns only take 5-6 seconds. Five to six seconds may be a conservative assumption for this many
1/4
-turns for some types of rollover. The FMVSS No. 208 dolly test has a very quick rollover initiation (high initial roll rate); the beginning of the rollover is well defined. However, the test only represents about 1% of field crashes.
61

The vast majority of field cases are soil and curb trip crashes. Soil trips involve high lateral deceleration in combination with low initial roll rates. Ideally, the curtain air bag should deploy in this early phase when the roll rate is still low but the occupant is moving towards the window due to the lateral deceleration. The rollover has a slow initiation, leading to a need for longer inflation. Therefore, some rollover crashes with less than eleven
1/4
-turns may have 5-6 second roll times. A factor that the agency also considered in determining the time delay for the lower speed impact was the practicability of curtains staying inflated for this length of time. Ford stated that its “Safety Canopy” system stays inflated for six seconds.
62

GM has reportedly stated that its side curtain air bags designed for rollover protection maintain 80 percent inflation pressure for 5 seconds.
63

61
Viano,
supra.

62

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

63
“Who Benefits From Side and Head Airbags?” (
http://www.edmunds.com/ownership/safety/articles/105563/article.html).

2. Speed at Which Occupants Impact or Move Through the Window Opening

This NPRM proposes that the impactor should strike the window opening countermeasure at a speed of 24 km/h (after a 1.5 second time delay after deployment of the countermeasure) and at 16 km/h (after a 6 second delay). The 24 and 16 km/h values are based on several analyses, discussed below, of speeds at which occupants impact or move through the window opening, including analysis of accident data, computer simulations and test films of rollover crashes.
64

In addition, the agency notes that the 24 km/h impact speed is consistent with the impact speed of FMVSS No. 201, “Occupant protection in interior impact” (49 CFR 571.201). FMVSS No. 201 uses a free-motion headform with a 4.6 kg mass to strike vehicle upper interior locations including areas around side window openings. The impact speed for these tests is 24 km/h.
65

64
It is noted that the DRF test data presented above that showed far side occupant velocities of approximately 30 km/h (Duffy, “Test Procedure for Evaluating Ejection Mitigation Systems”) also support the proposed test speeds.

65
The 24 km/h speed was chosen in part because it is the average speed at which the onset of AIS 2 and AIS 3 injuries are likely to occur.

Accident Data

In the analysis of accident data, the agency investigated side impact accident data to determine the ΔV of the crashes in which near side impact occupants were completely ejected. This data is depicted in Figure 3, which shows the cumulative percentage of near side impact occupants completely ejected, by impact ΔV. This graph represents 15,062 occupant ejections weighted from 704 NASS ejection cases. The range of the ΔV was 2 to 55 km/h. With regard to the proposed impact test speeds of 16 and 24 km/h, 47.6 percent of the near side impact occupants were completely ejected at ΔVs at or below 16 km/h, while 65.5 percent of the

occupants were ejected at ΔVs at or below 24 km/h.

EP02DE09.002

Computer Simulations

NHTSA analyzed MADYMO simulations of the real-world rollovers of the Toyota pickup, Toyota Corolla and Volkswagen Jetta,
supra.
As shown in Table 10,
supra,
the computed resultant maximum head and torso velocities at contact with the intact glazing for the unejected occupant indicated a maximum head speed into the window openings of 22 km/h. The maximum head velocity was 22 km/h for the Jetta unrestrained occupant into the window opening. The maximum torso velocity was 16 km/h, also for the unrestrained Jetta occupant.

Film Analyses of Full Vehicle Rollover Tests

In the early 1990's the agency reviewed 23 of 28 full-scale rollover tests performed in the 1970s-1990s to find any cases of occupant to side glazing impact and to determine the contact velocities. In seven of these tests, the occupant was observed striking the side glazing with either the head or shoulder. As shown in Table 13, a film analysis was conducted to measure the velocity of the impacts.
66

The average impact velocity measured was 8.6 km/h. Maximum and average head velocities were 17.0 km/h and 10.3 km/h, respectively. Maximum and average shoulder velocities were 8 km/h and 6.3 km/h, respectively.
67

66
The analysis is limited by the fact that a single camera was used to determine the velocities.

67
These measurements compare very closely to the measurements reported in DOT HS476-PM-83-25. This report evaluated 48 FWHA rollover tests involving passenger cars. In these tests, they found six occupant/glazing impacts (5 head, 1 shoulder). An average impact velocity of 10.9 km/h was measured. Maximum and average head velocities were 17.8 km/h and 11.3 km/h, respectively. The only measured shoulder velocities were 8 km/h and 8.7 km/h.

Table 13—Film Analysis of NHTSA Rollover Tests

Test #
Make
Model
Test type

Vehicle test speed
(km/h)

Occupant
impact speed
(km/h)

Contact point

878
Honda
84 Accord
RTD
33.8
8.0
Shoulder.

No test #
Dodge
Aries
Guardrail
96.6
16.0
Head.

888
Chevrolet
82 Celebrity
RTD
37.0
6.5
Shoulder.

No test #
Ford
Pinto
Dolly
27.4
2.5
Head.

No test #
Dodge
Reliant
RTD
33.8
4.5
Shoulder.

1520
Ford
88 Ranger
RTD
48.3
5.8
Head.

1522
Nissan
88 Pickup
Pole
48.3
17.0
Head.

Average

8.61

Based on the above information, the agency is proposing two impact speeds and time delays. NHTSA requests comment on the appropriateness of the impact speeds and of the time delay for both the high and low speed impacts. If alternative impact speeds and/or time delays are suggested, what are the rationale and data supporting that suggestion?

3. Alternative Testing of Only One Target Position at Higher Speed

The agency proposes to subject all four target locations (per window opening) to the 16 km/h (6 second time delay) impact, but requests comments on whether to test all four target locations with a 24 km/h (1.5 second time delay) impact or just the location with the greatest displacement in the 16 km/h impact. The latter approach would reduce the test burden per window opening from eight targets to five. Our analysis of available data shows that there appears to be a correlation between the displacement results for the 24 km/h and the 16 km/h impacts, particularly for the target location with the greatest displacement. That is, the weakest point in the countermeasure (curtain) that allows the most displacement of the headform could be the same for the 24 km/h impact as for the 16 km/h impact. If the weakest point in the countermeasure is the same for each impact test, it may be possible to reduce the number of tests for one of the impact speeds to a single location. If a correlation exists, an approach the agency could take would be to first determine the displacement at each target location for the 16 km/h (6 second time delay) impact and rank the displacement results from largest to smallest. The agency would then subject only the target with the largest displacement to the 24 km/h (1.5 second delay) second impact. Under this scenario, if the weakest target passes the 24 km/h test, it would be reasonable to assume that the other targets would also have displacements under 100 mm in 24 km/h test. If the weakest target fails the 24 km/h test, the vehicle would fail the requirements of the FMVSS proposed today and there would not be a need to test the other targets.

There are test data demonstrating that the target locations with the most displacement at each test speed are generally the same, but the data are limited. Table 14 shows the impactor displacement results for the MY05 Infinity FX35 (front window), the Zodiac prototype on a Navigator (front window), a TRW prototype on a CK (front window), the MY06 Durango (second row window), and the MY05 Honda Odyssey (second row window). Table 15 shows the displacement rank for each target location and vehicle, from most displacement to least displacement.

For the MY05 Infinity FX35, in the 24 km/h test, the largest and smallest displacements are A1 and A4, respectively. For the 16 km/h test of the Infinity, the ascending displacement ranking is A1, A3, A2 and A4. However, for the 24 km/h test, three trials were performed at A2 and A3 and there is significant overlap in the displacement data. The average displacement plus or minus one standard deviation is shown in the table. In fact, there is no statistically significant difference between the average results of 97 mm at A2 and 95 mm at A3. For the Zodiac prototype data, the ranking of the displacement data at both impact speeds is A1, A3, A2 and A4. For the TRW prototype, the ranking is also identical at both speeds, but the ranking is A1, A2, A3 and A4, which is different from the Zodiac. The target locations for the Odyssey's largest and smallest displacements (A1 and A4, respectively) are the same in the 16 km/h tests as for the 24 km/h impacts.

For the second row window data, the MY06 Durango ranks the displacement at both test speeds as B3, B2, B4 and B1, in ascending order. However, at 24 km/h there is very little separating the displacements at each location. The MY 05 Honda Odyssey has the displacement ranking at the 24 km/h test of B4, B2, B3, and B1. However, for the 16 km/h test the displacement ranking is B2, B3, B4 and B1.

In general, this very limited data set shows a consistency in the displacement results for each impact test speed, particularly for the location of greatest displacement for the front window (A1). For the second row window, the Dodge Durango had consistent results, but the Honda Odyssey did not.

We note that this alternative of performing a single 24 km/h impact at the target that gives the largest displacement in the 16 km/h impact has not been analyzed in the Preliminary Regulatory Impact Analysis (PRIA). However, this does not mean there would be no difference in cost or safety benefits. Rather, assessing this difference would require sufficient data to determine the probability of having a 24 km/h impact displacement greater than 100 mm at some location other than the location of greatest displacement at 16 km/h. We do not have sufficient data for such an assessment.

Comments are requested on whether the 24 km/h impact should only be conducted on the target location with largest displacement in the lower speed test. If results for multiple targets at 16 km/h are within the variance for the test, which target should be selected for the 24 km/h test? The agency's supporting documents for this NPRM estimate the likely test burdens associated with the two approaches. The agency estimates that the restricted testing approach would reduce the number of tests to determine full compliance by 38 percent, while reducing the costs of testing by 8 percent. Please comment on the potential advantages and disadvantages of each method and how the agency might best balance both the safety and potential test burdens.

Table 14—Displacements for Vehicle Windows Where All Targets Were Impacted
[mm]

Position A1
Position A2
Position A3
Position A4

24 km/h—1.5 sec. Delay:

05 Infinity FX35
124
97 ± 14.5
95 ± 11.0
53

Zodiac Prot. On Navigator
147 ± 4.9
54
99 ± 4.2
23 ± 2.1

TRW Prot. On CK w/lam
181 ± 1.4
21
−26 ± 0.0
−29 ± 5.7

16 km/h—6 sec. Delay:

05 Infinity FX35
85
21
39
9

Zodiac Prot. On Navigator
135
49
80 ± 2.1
−0.2

TRW Prot. On CK w/lam
80
−3
−44
−67

Position B1
Position B2
Position B3
Position B4

24 km/h—1.5 sec. Delay:

05 Honda Odyssey
71 ± 8.5
152
80
193

06 Dodge Durango
76
86
91
82

16 km/h—6 sec. Delay:

05 Honda Odyssey
12
121 ± 0.7
55
28

06 Dodge Durango
3
36
71
18

Table 15—Displacement Rank (From Left to Right, Most Displacement to Least Displacement), for Each Vehicle and Target Location

Vehicle
16 km/h—6 sec. delay
24 km/h—1.5 sec. delay

05 Infinity FX35
A1, A3, A2, A4
A1, A2, A3, A4.

Zodiac Prot. on Navigator
A1, A3, A2, A4
A1, A3, A2, A4.

TRW Prot. on CK w/lam
A1, A2, A3, A4
A1, A2, A3, A4.

05 Honda Odyssey
B2, B3, B4, B1
B4, B2, B3, B1.

06 Dodge Durango
B3, B2, B4, B1
B3, B2, B4, B1.

d. Locations Where the Device Would Impact the Ejection Mitigation Countermeasure To Assess Efficacy

1. Occupants Are Mainly Ejected Through Side Windows

NHTSA analyzed 1997 to 2005 NASS CDS data files to determine the injury and fatality distribution by ejection routes.
68

Table 16 shows the MAIS 1-2, MAIS 3-5 and fatality distribution of ejected occupants by eight potential ejection routes.
69

Ejection through side windows constitutes the greatest part of the ejection problem. There were 18,353 MAIS 1-2 injuries, 5,271 MAIS 3-5 injuries, and 6,174 fatalities for occupants ejected through side windows. Table 17 gives the percentage of the total at each injury level. The side window ejections comprise 68 percent of all ejected MAIS 1-2 injuries, 47 percent of MAIS 3-5 injuries, and 61 percent of all ejected fatalities. Because of these data, NHTSA focused on the safety problem posed by side window ejections.

68
All crash types are included, but the counts are restricted to ejected occupants that were injured. In addition, in NASS CDS the ejection route for side windows is only explicitly coded for the front (Row 1 Window) and rear (Row 2 Window). The third and higher row side window ejections should be coded as “other glazing.” This is because there are specific codes available for coding roof glazing, windshield and backlight. However, when extracting NASS cases of known ejections through “other glazing,” 17 unweighted occupants were observed. A hard copy review of these 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.

69
The “Not Window” category captures ejected occupants that did not go through a glazing area. This might have been an open door or an area of vehicle structure that was torn away during the crash.

Table 16—Occupant Injury and Fatality Counts by Ejection Route in All Crash Types
[Annualized 1997-2005 NASS, 2005 FARS]

Ejection route
MAIS 1-2
MAIS 3-5
Fatal

Row 1 Window
15,797
4,607
5,209

Row 2 Window
2,533
621
906

Row 3 Window
23
43
59

Windshield
1,923
1,565
1,155

Backlight
1,625
1,677
515

Sun Roof
1,127
305
237

Other Window
1
51
0

Not Window
3,870
2,411
2,068

Subtotals:

All Side Windows
18,353
5,271
6,174

Total
26,899
11,280
10,149

Table 17—Occupant Injury and Fatality Percentages by Ejection Route in All Crash Types
[Annualized 1997-2005 NASS, 2005 FARS]

Ejection route

MAIS 1-2
(percent)

MAIS 3-5
(percent)

Fatal
(percent)

Row 1 Window
58.7
40.8
51.3

Row 2 Window
9.4
5.5
8.9

Row 3 Window
0.1
0.4
0.6

Windshield
7.1
13.9
11.4

Backlight
6.0
14.9
5.1

Sun Roof
4.2
2.7
2.3

Other Window
0.0
0.5
0.0

Not Window
14.4
21.4
20.4

Subtotals:

All Side Windows
68.2
46.7
60.8

Total
100.0
100.0
100.0

2. The Requirements Would Apply to Side Windows Adjacent to First Three Rows

NHTSA evaluated crash data to assess which window, by row, the above injured and killed occupants were ejected through. Table 18 provides the counts of the injured and killed side window ejected occupants by the window row they were ejected through, ejection degree (complete or partial) and restraint condition for the target population of this rule. Table 19 shows the same data as a percentage of total side window ejected fatalities, MAIS 3-5 and MAIS 1-2 injuries. The first row (row 1) windows provide the ejection route for the most injured and killed occupants. There were 2,459 fatalities and 2,243 MAIS 3-5 injuries that were unbelted and completely ejected through the row 1 windows. The greatest number of fatally ejected occupants (3,671) went through the row 1 window. This represents 83 percent of all side window ejected fatalities. With regard to injuries, 3,735 (88 percent) MAIS 3-5 and 11,016 (87 percent) MAIS 1-2 injured occupants went through the row 1 windows. Ejection routes through row 1 and row 2 windows accounted for more than 99 percent of fatal and 98 percent of MAIS 3-5 completely ejected and unbelted occupants. These data show a compelling safety need to apply the ejection mitigation standard to row 1 and row 2 windows.

Table 18—Distribution of Target Population by Ejection Row and Injury Level by Ejection Degree and Belt Use
[Annualized 1997-2005 NASS, 2005 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
92
16
69
12
40
0
0
30
0

Complete
No
3,968
2,243
2,459
1,484
324
588
22
7
38

Partial
Yes
4,464
1,086
526
58
42
45
0
7
0

Partial
No
2,492
391
617
119
64
53
0
0
0

Total

11,016
3,735
3,671
1,673
471
686
22
43
38

Table 19—Distribution of Target Population by Ejection Row and Injury Level by Ejection Degree and Belt Use, as a Percentage of Totals at Each Injury Level
[Annualized 1997-2005 NASS, 2005 FARS]

Ejection degree
Belted
Row 1

MAIS 1-2
(percent)

MAIS 3-5
(percent)

Fatal
(percent)

Row 2

MAIS 1-2
(percent)

MAIS 3-5
(percent)

Fatal
(percent)

Row 3

MAIS 1-2
(percent)

MAIS 3-5
(percent)

Fatal
(percent)

Complete
Yes
1
0
2
0
1
0
0
1
0

Complete
No
31
53
56
12
8
13
0
0
1

Partial
Yes
35
26
12
0
1
1
0
0
0

Partial
No
20
9
14
1
2
1
0
0
0

Total

87
88
84
13
11
16
0
1
1

We would also apply the standard to row 3 windows. All light vehicle (GVWR 4,536 kg (10,000 lb) or less) rollover occupants in the target population for this proposal were ejected through the windows of the first 3 rows. Third and higher row windows are not specifically coded as ejection routes in NASS, so the “other” window categories were reviewed. These categories contained only a limited number of 3rd row window ejections (about 1 percent of fatalities and MAIS 3-5 injuries). While the percentage of ejection through the third and higher rows is small, this might be a reflection of the very few light vehicles with more than three rows and the low occupancy in third and higher rows. NHTSA is concerned that in a crash, an unbelted occupant could be ejected from the 3rd row window opening. As discussed in IV(b)(2) of this preamble, the agency has observed laboratory DRF tests in which an unbelted dummy was initially prevented from ejection by a side curtain, but was eventually ejected

when it slid to an opening in the curtain. Further, with substantial numbers of 3-row vehicles used as passenger vehicles, applying the standard to row 3 as well as rows 1 and 2 windows would be consistent with the SAFETEA-LU mandate “to establish performance standards to reduce complete and partial ejections of vehicle occupants from outboard seating positions.”

In addition, it appears practicable for manufacturers to meet ejection mitigation requirements applying to the row 3 windows. There are a number of current OE air bag curtains that cover rows 1, 2 and 3 windows, such as the 2005-2007 MY Honda Odyssey, 2006 Mercury Monterey, 2007 Chevrolet Tahoe, and 2007 Ford Expedition.

Less can be said about the practicability of air bag curtain coverage beyond three rows of seating. Vehicles in this category are primarily large vans with more than 10 seating positions and are in the bus category. We do not believe that manufacturers have installed air bag curtains that cover beyond the third row windows in vehicles that have more than three rows. Thus, we would not apply the standard to windows for row 4+.

Out of concern to properly assess the cost impact of this rulemaking, we are also proposing to limit the testable area of window openings extending rearward past the designated seating positions of the first three rows. This NPRM proposes that, for vehicles with 3 rows, for any side window opening that extends rearward of a 3rd row forward-facing designated seating position (DSP), the rearward edge of the testable side window opening would be bound by a transverse vertical vehicle plane 600 mm (approximately 24 inches) behind the seating reference point (SgRP) of the 3rd row DSP. If the 3rd row designated seating position is adjustable to a non-forward facing orientation, the target area extends to 600 mm behind the rearmost portion of the seat when the seat is adjusted to the most rearward position (with respect to the vehicle) and the seat cushion and seat back are in the manufacturer's design position. So if a vehicle's third row seat has both a forward and a rearward facing position, the testable area would be determined as specified above. The final target area would be the largest area as defined under either of these conditions,
i.e.,
(1) by the SgRP of the forward facing seat, or (2) the most rearward part of the non-forward facing seat. This limitation of testable area would also be applied to the 2nd row window in two-row vehicles and 1st row window in one-row vehicles. The limitation would primarily affect sport utility vehicles (SUVs) with two rows of seating and side window areas adjacent to the rear cargo area. While it is not impossible for unbelted occupants to be partially or completely ejected through this area, we believe that ejection through a non-adjacent opening more than 600 mm from the occupant's SgRP is less likely. We note that FMVSS No. 201 has a similar exclusion in S6.3 that excludes impact targets 600 mm rearward of the rearmost SgRP. We also note that changes to the seating configuration for vehicles with removable or stowable seats must be considered in the determination of the rearward limit of the testable area. We propose that the seating configuration that generates the largest testable area would be used.

This NPRM proposes a definition of the term “row,” since the proposed regulatory text frequently refers to the term in describing the applicability of the ejection mitigation requirements. While the definition of the term is generally understood, under the proposed definition we would clarify that a single seat could constitute a “row.” The proposed definition of “row” would state: “Row” means a set of one or more seats whose seat outline does not overlap with the seat outline of any other set of seats, when all seats are to their rearmost normal riding or driving position, when viewed from the side.
70

70
Stated differently, the seats are adjusted such that their design H-point coincides with seating reference point.

In consideration of the above definition of “row” we believe it is necessary to define “seat outline.” The proposed definition of “seat outline” would state: “Seat outline” means the outer limits of a seat projected laterally onto a vertical longitudinal vehicle plane.

We believe that the definition is needed to address potential questions about vehicles that appear in one seating configuration to have 2 conventional rows of seating, but which have a seat or seats in a row (
e.g.,
the 2nd row) that are capable of being adjusted forward or rearward independently from other seats in its row. For example, suppose a seat in the 2nd row can move rearward such that it can occupy a position occupied by a seat traditionally considered to be in the 3rd row. NHTSA tentatively believes that a reasonable way of addressing this issue is as follows. First, the vehicle seats must be adjusted such that they are in the SgRP position. This places each seat in the rearmost normal driving or riding position. The transition for a seat being in one row as opposed to another is the overlapping of the side view “seat outline” of the seats. Seats whose seat out

[Text truncated at 120,000 characters. The full text is on the page linked above.]

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Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/fr%3AE9-28177. Public record. Not legal advice.