Federal Motor Vehicle Safety Standards; Occupant Crash Protection
Federal RegisterJan 6, 1997
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DEPARTMENT OF TRANSPORTATION
National Highway Traffic Safety Administration
49 CFR Part 571
[Docket No. 74-14; Notice 108]
RIN 2127-AG59
Federal Motor Vehicle Safety Standards; Occupant Crash Protection
AGENCY: National Highway Traffic Safety Administration (NHTSA), DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: NHTSA is proposing to amend the agency's occupant crash
protection standard to ensure that vehicle manufacturers can depower
all air bags so that they inflate less aggressively. The agency is
taking this action as part of its comprehensive efforts to reduce the
fatalities and injuries that current air bag designs are causing in
relatively low speed crashes to small, but growing numbers of children,
and occasionally to adult drivers. Taken together, these efforts would
affect all existing air bag vehicles, as well as those produced in the
next several model years.
Based on agency research and analysis regarding the optimal range
of air bag ``depowering,'' the agency has tentatively concluded that an
average depowering of 20 to 35 percent would reduce the risk of
fatalities in low speed crashes, while substantially preserving the
life saving capabilities of air bags in higher speed crashes. The
agency is considering the adoption of either, or both, of two different
approaches that would permit or facilitate, but not require, such
depowering of current air bags. One approach would be to reduce the
stringency of the chest acceleration requirement which an unbelted
dummy must meet in a crash test at speeds up to 30 mph. The other
approach was recently requested by the American Automobile
Manufacturers Association in a letter superseding its earlier petition
for rulemaking. It would replace the unbelted crash test requirement
with a sled test protocol incorporating a 125 millisecond standardized
crash pulse. NHTSA is seeking comments and information concerning the
relative desirability of these two approaches, including supporting
data from industry for the sled test. The agency also seeks comments on
whether the same or different requirements should apply to the
passenger and driver positions.
There is a possibility that while this rulemaking would prevent a
significant number of air bag fatalities, and make it possible to
design air bags so that they save increased numbers of belted
occupants, it could also result in an even larger number of unbelted
occupants not being saved by air bags. Accordingly, the agency is
requesting comments on the appropriate duration of such an amendment.
If there are adverse safety tradeoffs, and smart air bags offer a way
of preventing air bag fatalities while not causing similar tradeoffs,
it would be desirable to limit the duration of the amendment so that
depowering is only an interim measure. NHTSA currently contemplates
that the amended requirement would remain in effect for both passenger
and driver air bags until smart air bags are installed pursuant to a
mandated phase-in schedule. Establishing that schedule and appropriate
performance requirements will be the subject of a separate rulemaking
proceeding.
NHTSA is also announcing its granting of a petition by Anita Glass
Lindsey to commence a rulemaking proceeding to consider whether to
specify the use of a dummy representing a small-statured female in
testing the performance of safety belts and air bags.
DATES: Comments must be received by February 5, 1997.
ADDRESSES: Comments should refer to the docket and notice number of
this notice and be submitted to: Docket Section, Room 5109, National
Highway Traffic Safety Administration, 400 Seventh Street, SW,
Washington, DC 20590. (Docket Room hours are 9:30 a.m.-4 p.m., Monday
through Friday.)
FOR FURTHER INFORMATION CONTACT: For information about air bags and
related rulemakings: Visit the NHTSA web site at http://
www.nhtsa.dot.gov and select ``AIR BAGS: Information about air bags.''
For non-legal issues: Mr. Clarke Harper, Chief, Light Duty Vehicle
Division, NPS-11, National Highway Traffic Safety Administration, 400
Seventh Street, SW, Washington, DC 20590. Telephone: (202) 366-2264.
Fax: (202) 366-4329.
For legal issues: J. Edward Glancy, Office of Chief Counsel, NCC-
20, National Highway Traffic Safety Administration, 400 Seventh Street,
SW, Washington, DC 20590. Telephone: (202) 366-2992. Fax: (202) 366-
3820.
SUPPLEMENTARY INFORMATION:
Table of Contents
I. Background.
A. How Air Bags Work.
B. Circumstances of Air Bag Fatalities.
II. The Safety Problem: Frontal Impacts and Air Bags--Lives Saved,
and Lives Lost.
A. Frontal Impacts.
B. Air Bags: Lives Saved, and Lives Lost.
III. Search for Solutions.
A. The Early Years.
B. The Last Five Years.
C. Recent Petitions for Rulemaking.
IV. Overview of Comprehensive NHTSA Plan for Addressing Problem.
V. Depowering Air Bags
A. Results of NHTSA Test Program
B. Effects of Depowering and Optimizing
1. Passenger Air Bags
2. Driver Air Bags
C. Alternative Proposals
1. Approach I--Temporary Change in Unbelted Chest Acceleration
Requirement.
2. Approach II--Temporary Replacement of Unbelted Crash Test
Requirement with a Sled Test Protocol Incorporating a Standardized
Crash Pulse.
3. Request for Additional Information.
D. Consideration of Other Alternatives.
E. Effective Date and Comment Period.
F. Relationship to Other Actions.
VI. Response to AAMA and CFAS Petitions.
VII. Granting of Petition to Consider Using 5th Percentile Female
Dummy.
VIII. Rulemaking Analyses and Notices.
A. Executive Order 12866 and DOT Regulatory Policies and
Procedures.
B. Regulatory Flexibility Act.
C. National Environmental Policy Act.
D. Executive Order 12612 (Federalism).
E. Civil Justice Reform.
IX. Request for Comments.
Appendix: Past Public Comments Related to Depowering Air Bags.
I. Background
In 1984, the Department of Transportation issued a final rule
requiring the installation of automatic protection (e.g., air bags,
automatic belts, passive interiors) in passenger cars. 49 Fed. Reg.
28962; July 17, 1984. The Department took this step to increase the
protection of vehicle occupants, especially unbelted ones. At the time,
only 12.5 percent of occupants wore their safety belts, and only one
state required all motorists to buckle up.
In 1991, Congress mandated the installation of air bags in both
passenger cars and LTV's with a gross vehicle weight rating (GVWR) of
8,500 pounds or less. (LTV's generally include vans, pickup trucks,
buses, and sport utility vehicles with a gross vehicle weight rating of
10,000 pounds or less). The Intermodal Surface Transportation
Efficiency Act required that air bags be put in all new cars by the
beginning of model year 1998 and in all new LTV's by the beginning of
model year 1999.
Much has changed since 1984, and even since 1991. The cumulative
production of air bag cars and LTV's reached the 10,000,000 mark for
driver air bag vehicles during model year 1992 and for dual air bag
vehicles during model year 1995. Air bags are now standard equipment on
most passenger
[[Page 808]]
cars and LTV's. As of the end of model year 1996, approximately 56
million air bag vehicles have been produced for sale in the United
States. 1 Safety belt use has reached approximately 68 percent.
2 Forty-nine States and the District of Columbia require the use
of safety belts, and all jurisdictions require the use of child safety
seats. While males account for a sizable majority of the nonusers of
safety belts, females still account for 40 percent of the nonusers.
3
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\1\ Over 27,000,000 of those vehicles have both driver and
passenger air bags.
\2\ Belt use among fatally injured front seat occupants of cars
and LTV's is lower, approximately 37 percent, based on 1995 data
from the Fatal Accident Reporting System (FARS). The lowness of this
rate reflects a number of factors, including the belt use rate by
motorists in general and the effectiveness of belt use in preventing
fatal injury. A more useful belt use rate is the rate among
occupants involved in potentially fatal crashes. Those crashes
include all fatal crashes as well as all crashes in which there
would have been a fatality but for belt use. The use rate in
potentially fatal crashes is slightly over 50 percent.
\3\ This figure is based on a September 1994 study by Reinfurt
et al. of belt use in North Carolina.
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NHTSA estimates that air bags have deployed more than 800,000 times
in crashes and have saved approximately 1,664 lives (164 passengers and
1,500 drivers) as of November 1996. Unfortunately, air bags also have
fatally injured at least 32 children, 1 adult passenger, and 19 drivers
in low severity crashes in the United States. Apart from the nine
fatally-injured infants (included in the figure of 32 above), most of
the fatally-injured occupants were unbelted. Thus, while the number of
people being saved by air bags is growing annually, so is the much
smaller, but significant number of people being fatally injured by air
bags.
A. How Air Bags Work
When a vehicle has a frontal impact, its occupants begin to move
forward in response to pre-impact braking or the deceleration of the
vehicle during the impact. If unrestrained, front-seat occupants will
move forward in a fraction of a second and hit the steering wheel,
dashboard or windshield. To move into place in time to catch the
occupants in moderate and high speed crashes, air bags must inflate
very quickly--faster than the blink of an eye.
To ensure that the air bag provides enough resistance to keep large
as well as small occupants from ``bottoming out'' the air bag and
hitting the vehicle interior, the amount of gaseous pressure within air
bags must be carefully modulated. This is done by controlling both the
rate at which gas is pumped into the air bag as well as the rate at
which the gas is released from the air bag through vents or the
porosity of the fabric.
An example from a non-automotive context will help to show the
importance of modulating the air pressure in air bags. Vented air
cushions are sometimes used by stunt performers who jump or dive from a
great height to absorb the energy of their fall. If the vents don't
allow enough of the pressure in the cushion to be released as the
performer hits it, the cushion will be too rigid and will fail to
absorb enough of the performer's energy, causing injury. On the other
hand, if the vents release too much pressure, the cushion will ``bottom
out,'' thus allowing the performer to strike the ground, also causing
injury.
B. Circumstances of Air Bag Fatalities
Air bags need time, and space, to inflate. The sudden release of
energy by an inflating air bag can harm some front seat occupants,
particularly if they are too close to the air bag at the time of
deployment. Properly restrained occupants of a vehicle seat moved back
from the dashboard as far as possible, and even most unrestrained
teenagers and adults, will meet the air bag after the initial, sudden
release of energy. However, some occupants either start out very close
to the steering wheel or dashboard or end up there. Most child
fatalities attributed to an air bag fall into one of two groups: (1)
infants riding in rear-facing infant seats, thus placing them very
close to the air bag at the time of deployment, or (2) older children
riding forward-facing without any type of restraint, thus allowing them
to slide forward during pre-crash braking so that they were too close
to the air bag when it deployed. A majority of the fatally-injured
drivers were short-statured women who moved the driver's seat forward.
More than half of the fatally-injured drivers were not using any type
of restraint.
II. The Safety Problem: Frontal Impacts and Air Bags--Lives Saved, and
Lives Lost
The number of air bag fatalities and the likelihood of those
fatalities must be carefully compared to the likelihood of other
related events in evaluating solutions to the causes of those
fatalities.
A. Frontal Impacts
Frontal impacts are the number one fatality and injury-causing mode
of crash, resulting in 64 percent of all driver and right-front
passenger fatalities and 65 percent of all driver and right-front
passenger AIS 2-5 injuries. (AIS 2-5 stands for Abbreviated Injury
Scale levels of moderate to critical injuries.) The estimated fatality
and injury totals for 1994 are shown below. The injuries are those for
National Accident Sampling System-Crashworthiness Data System (NASS-
CDS) towaway accidents only. (See table below.)
1994 Fatalities and Moderate to Serious Injuries in Frontal Impacts
[Passenger Cars and Light Trucks]
------------------------------------------------------------------------
Right front
Drivers passengers Total
------------------------------------------------------------------------
Fatalities........................... 13,437 3,814 17,251
Injuries............................. 124,484 30,299 154,783
----------------------------------
Total.......................... 4 137,921 5 34,113 172,034
------------------------------------------------------------------------
4 The numbers of fatalities and injuries for drivers far exceed those
for passengers in large measure because approximately 80 percent of
front seat occupants are drivers.
5 The figures for right front passengers include the following figures
for children under the age of 13: approximately 266 fatalities and 643
moderate to serious injuries.
[[Page 809]]
B. Air Bags: Lives Saved, and Lives Lost
As the agency has confronted the problem of low speed fatalities
and injuries from air bags, it has faced a serious dilemma. On the one
hand, air bags have proven to be highly effective in reducing
fatalities, and are resulting in substantial net benefits in terms of
lives saved. The agency estimates that, to date, air bags have saved
1,664 drivers and passengers (1,500 drivers and 164 passengers).6
Current air bags could save an estimated slightly more than 3,000 lives
each year in passenger cars and light trucks when all cars on the road
are equipped with dual air bags.
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\6\ This estimate of gross savings is cumulative, through
November 1, 1996. The net savings would be 1,612.
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At the same time, air bags are actually causing fatalities in some
situations, especially to children. As of November 30, 1996, NHTSA's
Special Crash Investigation program had identified 32 crashes in this
country in which the deployment of the passenger air bag resulted in
fatal injuries to a child. The agency has examined all air bag cases
with child fatalities in its Fatal Accident Reporting System (FARS) and
believes it has identified all cases involving air bag-related
fatalities. One adult passenger has been fatally injured (a woman in
her 90's). On the driver side, 19 drivers 7 have been fatally
injured in this country. (See table below.)
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\7\ The figure of 19 is based on information that NHTSA has
developed through NHTSA's Special Crash Investigation program and is
not a census. Studies of FARS data are underway to obtain a more
precise figure.
Air Bags: Cumulative Lives Saved and Fatalities Caused (1986-Present)
[Passenger Cars and Light Trucks]
------------------------------------------------------------------------
Right front
Drivers passengers Total
------------------------------------------------------------------------
Lives saved.......................... 1,500 164 1,664
Fatalities caused.................... 19 33 52
----------------------------------
Net lives saved................ 1,481 131 1,612
------------------------------------------------------------------------
Passenger Fatalities. The annual number of fatalities involving
children is steadily growing; all have occurred in 1993 and later
calendar years. As noted above, 32 children have been fatally injured
to date. (See tables below.)
It appears that the children most at risk are infants in rear-
facing infant restraints and children not using any type of restraint.
All of the infant fatalities (9) involved infants in rear-facing child
seats. Most of the other children were not using any type of safety
restraint. Of those other children, 18 were unrestrained, two more were
wearing only the lap belt with the shoulder belt behind them, and two
were wearing a lap and shoulder belt at the time of the crash. In
addition, there was a one-year-old child who was fatally injured while
riding in a child seat that was not belted to the vehicle seat. (See
table below.)
Most children were either infants or children aged 4-7 years old.
(See table below.)
The crashes in which the children were fatally injured involved
pre-impact braking, and occurred at relatively low speeds. Infants in
rear-facing child seats are very close to the dashboard even before
pre-impact braking. As to almost all of the older children, the nonuse,
or improper use of safety belts in conjunction with pre-impact braking
resulted in their forward movement such that they were very close to
the instrument panel and the air bag system when the air bag deployed.
Because of this proximity, the children appear to have sustained fatal
head or neck injuries from the deploying passenger air bag.
In addition to the 32 children who have been fatally injured during
passenger air bag deployments, as noted above, one adult, a woman in
her 90's, sustained a fatal injury that appears to be due to an air bag
deployment.
Infant Passenger Air Bag-Related Fatalities (in Rear-Facing Infant Seats)
[By MY of Vehicle and CY of Fatality]
--------------------------------------------------------------------------------------------------------------------------------------------------------
Total No. No. of
of infant vehicles
CY 89 CY 90 CY 91 CY 92 CY 93 CY 94 CY 95 CY 96 passenger produced w/
air bag passenger air
fatalities bags
--------------------------------------------------------------------------------------------------------------------------------------------------------
MY 89............................................... ....... ....... ....... ....... ....... ....... ....... ....... .......... 78,000
MY 90............................................... ....... ....... ....... ....... ....... ....... ....... ....... .......... 149,000
MY 91............................................... ....... ....... ....... ....... ....... ....... ....... ....... .......... 44,000
MY 92............................................... ....... ....... ....... ....... ....... ....... ....... ....... .......... 421,000
MY 93............................................... ....... ....... ....... ....... ....... ....... ....... ....... .......... 1,352,000
MY 94............................................... ....... ....... ....... ....... ....... ....... 1 1 2 5,547,000
MY 95............................................... ....... ....... ....... ....... ....... ....... 2 4 6 8,936,000
MY 96............................................... ....... ....... ....... ....... ....... ....... ....... 1 1 10,750,000
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Total......................................... ....... ....... ....... ....... ....... ....... 3 6 9 27,277,000
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[[Page 810]]
Child (Non-Infant) Passenger Air Bag-Related Fatalities
[By MY of Vehicle and CY of Fatality]
--------------------------------------------------------------------------------------------------------------------------------------------------------
Total No.
of child
(non- No. of
CY 89 CY 90 CY 91 CY 92 CY 93 CY 94 CY 95 CY 96 infant) vehicles w/
passenger passenger air
air bag bags
fatalities
--------------------------------------------------------------------------------------------------------------------------------------------------------
MY 89............................................... ....... ....... ....... ....... ....... ....... ....... ....... .......... 78,000
MY 90............................................... ....... ....... ....... ....... ....... ....... ....... ....... .......... 149,000
MY 91............................................... ....... ....... ....... ....... ....... ....... ....... ....... .......... 44,000
MY 92............................................... ....... ....... ....... ....... ....... ....... ....... ....... .......... 421,000
MY 93............................................... ....... ....... ....... ....... 1 1 1 ....... 3 1,352,000
MY 94............................................... ....... ....... ....... ....... ....... 3 1 1 5 5,547,000
MY 95............................................... ....... ....... ....... ....... ....... 1 3 8 12 8,936,000
MY 96............................................... ....... ....... ....... ....... ....... ....... ....... 3 3 10,750,000
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Total........................................... ....... ....... ....... ....... 1 5 5 12 23 27,277,000
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Age of Children Fatally Injured in Air Bag Deployments
--------------------------------------------------------------------------------------------------------------------------------------------------------
8....................................................... 1
---------
Total..................................................... 32
------------------------------------------------------------------------
\8\ One fatally injured child was reportedly strapped into a forward
facing child seat, but the child seat was not attached to the vehicle
seat.
Driver Fatalities. As of November 15, 1996, NHTSA's Special Crash
Investigation (SCI) program had identified 19 minor to moderate
severity crashes in which fatal injuries to the driver were associated
with the deployment of the driver air bag.9 The data suggest that
unrestrained small-statured and/or older drivers are more at risk than
other drivers from a driver air bag. (See tables below.) The agency
notes that older drivers are more at risk than younger drivers under a
wide range of crash circumstances, regardless of type of restraint
used.
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\9\ But see footnote 7 below concerning reported driver
fatalities in Canada.
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NHTSA notes that these driver fatalities are very rare in
comparison to the number of vehicles equipped with driver air bags and
to the number of drivers saved by air bags. Further, NHTSA notes that
the last reported fatality in the United States of a female driver 5
feet 2 inches or shorter in an air bag deployment occurred in November
1995, 13 months ago.
Proper belt use is important. Ten of the 19 drivers were known to
have been unrestrained at the time of the crash. Of the six persons
properly using both lap and shoulder belts, two appeared to be out of
position (slumped over the wheel due to medical conditions). (See
tables below.)
Driver Air Bags: Fatalities and Lives Saved--All Drivers
[Fatalities Shown by MY of Vehicle and CY of Fatality]
--------------------------------------------------------------------------------------------------------------------------------------------------------
No. of
Driver air Drivers vehicles
CY 89 CY 90 CY 91 CY 92 CY 93 CY 94 CY 95 CY 96 bag saved by produced w/
fatalities air bag driver air
bags
--------------------------------------------------------------------------------------------------------------------------------------------------------
MY 89.................................... ....... ....... ....... ....... ....... ....... 1 ....... 1 ......... 500,000
MY 90.................................... ....... 1 1 ....... 1 2 1 ....... 6 ......... 2,500,000
MY 91.................................... ....... ....... 2 2 1 ....... 1 ....... 6 ......... 2,867,000
MY 92.................................... ....... ....... ....... ....... 1 1 ....... ....... 2 ......... 5,084,000
MY 93.................................... ....... ....... ....... ....... ....... ....... ....... ....... .......... ......... 7,597,000
MY 94.................................... ....... ....... ....... ....... ....... 2 1 ....... 3 ......... 9,886,000
MY 95.................................... ....... ....... ....... ....... ....... ....... ....... 1 1 ......... 13,686,000
MY 96.................................... ....... ....... ....... ....... ....... ....... ....... ....... .......... ......... 14,055,000
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Total................................ ....... 1 3 2 3 5 4 1 19 1,500 56,175,000
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[[Page 811]]
Driver Air Bag Fatalities--Women (5'2'' or Less)
[By MY of Vehicle and CY of Fatality]
--------------------------------------------------------------------------------------------------------------------------------------------------------
Total No.
of driver No. of
air bag vehicles
CY 89 CY 90 CY 91 CY 92 CY 93 CY 94 CY 95 CY 96 fatalities produced w/
(women driver air
5'2'' or bags
less)
--------------------------------------------------------------------------------------------------------------------------------------------------------
MY 89.............................................. ....... ....... ....... ....... ....... ....... 1 ....... 1 500,000
MY 90.............................................. ....... 1 ....... ....... 1 ....... 1 ....... 3 2,500,000
MY 91.............................................. ....... ....... 1 1 ....... ....... 1 ....... 3 2,867,000
MY 92.............................................. ....... ....... ....... ....... 1 1 ....... ....... 2 5,084,000
MY 93.............................................. ....... ....... ....... ....... ....... ....... ....... ....... ........... 7,597,000
MY 94.............................................. ....... ....... ....... ....... ....... ....... 1 ....... 1 9,886,000
MY 95.............................................. ....... ....... ....... ....... ....... ....... ....... ....... ........... 13,686,000
MY 96.............................................. ....... ....... ....... ....... ....... ....... ....... ....... ........... 14,055,000
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Total.......................................... ....... 1 1 1 2 1 4 ....... 10 56,175,000
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Driver Air Bag Fatalities--Other Adults
[By MY of Vehicle and CY of Fatality]
--------------------------------------------------------------------------------------------------------------------------------------------------------
Total No.
of driver No. of
air bag vehicles
CY 89 CY 90 CY 91 CY 92 CY 93 CY 94 CY 95 CY 96 fatalities produced w/
(other driver air
adults) bags
--------------------------------------------------------------------------------------------------------------------------------------------------------
MY 89............................................... ....... ....... ....... ....... ....... ....... ....... ....... .......... 500,000
MY 90............................................... ....... ....... 1 ....... ....... 2 ....... ....... 3 2,500,000
MY 91............................................... ....... ....... 1 1 1 ....... ....... ....... 3 2,867,000
MY 92............................................... ....... ....... ....... ....... ....... ....... ....... ....... .......... 5,084,000
MY 93............................................... ....... ....... ....... ....... ....... ....... ....... ....... .......... 7,597,000
MY 94............................................... ....... ....... ....... ....... ....... 2 ....... ....... 2 9,886,000
MY 95............................................... ....... ....... ....... ....... ....... ....... ....... 1 1 13,686,000
MY 96............................................... ....... ....... ....... ....... ....... ....... ....... ....... .......... 14,055,000
---------------------------------------------------------------------------------------------------
Total........................................... ....... ....... 2 1 1 4 ....... 1 9 56,175,000
--------------------------------------------------------------------------------------------------------------------------------------------------------
Age of Drivers Fatally Injured in Air Bag Deployments
--------------------------------------------------------------------------------------------------------------------------------------------------------
80 Total
--------------------------------------------------------------------------------------------------------------------------------------------------------
1............................................... 1 4 4 2 1 6 ........... 19
--------------------------------------------------------------------------------------------------------------------------------------------------------
Type of Restraint Used by Drivers Fatally Injured in Air Bag Deployments
------------------------------------------------------------------------
No. of
Type of restraint used drivers
------------------------------------------------------------------------
None.......................................................... 10
Belts misused................................................. 1
Lap and shoulder belt (Driver blacked out and slumped forward
at time of crash due to medical condition)................... 2
Lap and shoulder belt......................................... 4
Unknown....................................................... 2
---------
Total................................................... 19
------------------------------------------------------------------------
Comparison of Passenger and Driver Air Bag Fatalities
Several comparisons need to be drawn between the trends and
patterns of child fatalities and the apparent trends and patterns of
driver fatalities. The annual number of child fatalities is clearly
growing steadily as the number of deployments increases. The annual
number of adult fatalities does not appear to be growing. If anything,
it appears to be decreasing, based on currently identified fatalities.
(See tables below.)
Most child fatalities (24 of 32) have occurred in model year 1994
and 1995 vehicles. In contrast, only 4 of the 19 driver fatalities have
occurred in a vehicle manufactured after model year 1992. The absence
of fatalities in recent model year vehicles appears even more
pronounced in the case of women 5 feet 2 inches or shorter. Only one
woman 5 feet 2 inches or shorter has died in a post model year 1992
vehicle.\10\ Most fatalities of short-statured women occurred in model
year 1990-1992 vehicles. (See tables below.)
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\10\ NHTSA is aware of a number of fatalities in Canada
reportedly related to air bag deployment, but only two in recent
times. One was a November 1996 crash in Canada in which a 5 foot 3
inch belted female driver was fatally injured in a model year 1996
Ford Ranger. In addition, there was a November 1996 crash in which a
5 foot 2 inch belted female driver was fatally injured in a model
year 1993 Lexus. These Canadian accidents are not included in the
driver fatality figures cited in this notice. (Similarly, lives
saved by air bags outside the United States are not included in the
savings.)
[[Page 812]]
Comparison of Driver and Child Air Bag-Related Fatalities by Calendar Year of Fatality
----------------------------------------------------------------------------------------------------------------
CY 89 CY 90 CY 91 CY 92 CY 93 CY 94 CY 95 CY 96 Total
----------------------------------------------------------------------------------------------------------------
Drivers
----------------------------------------------------------------------------------------------------------------
Women (5'2'' or less).......... ....... 1 1 1 2 1 4 ....... 10
Other adults................... ....... ....... 2 1 1 4 ....... 1 9
--------------------------------------------------------------------------------
Total.................... ....... 1 3 2 3 5 4 1 19
----------------------------------------------------------------------------------------------------------------
Children
----------------------------------------------------------------------------------------------------------------
Children (non-infant).......... ....... ....... ....... ....... 1 5 5 12 23
Infants........................ ....... ....... ....... ....... ....... ....... 3 6 9
--------------------------------------------------------------------------------
Total.................... ....... ....... ....... ....... 1 5 8 18 32
----------------------------------------------------------------------------------------------------------------
Comparison of Driver and Child Air Bag-Related Fatalities by Model Year of Fatality
----------------------------------------------------------------------------------------------------------------
MY 89 MY 90 MY 91 MY 92 MY 93 MY 94 MY 95 MY 96 Total
----------------------------------------------------------------------------------------------------------------
Drivers
----------------------------------------------------------------------------------------------------------------
Women (5'2'' or less).......... 1 3 3 2 ....... 1 ....... ....... 10
Other adults................... ....... 3 3 ....... ....... 2 1 ....... 9
--------------------------------------------------------------------------------
Total.................... 1 6 6 2 ....... 3 1 ....... 19
----------------------------------------------------------------------------------------------------------------
Children
----------------------------------------------------------------------------------------------------------------
Non-infant Children............ ....... ....... ....... ....... 3 5 11 4 23
Infants........................ ....... ....... ....... ....... ....... 2 6 1 9
--------------------------------------------------------------------------------
Total.................... ....... ....... ....... ....... 3 7 17 5 32
----------------------------------------------------------------------------------------------------------------
Potential Number of Persons Saved Versus the Potential Number Fatally
Injured by Current Air Bags
The dilemma faced by NHTSA, and ultimately the public, is how to
address the problem of low speed fatalities from air bags while
preserving their substantial life-saving benefits. Based on analyses of
real world data, NHTSA estimates that if all passenger cars and light
trucks on the road today had current air bags, there would be more than
3,000 lives saved each year, as compared to a no-air-bag fleet
(assuming current belt use rates). More than two-thirds of the persons
saved would be persons not using any type of safety belt.
On the driver side, 616 belted drivers and 1,686 unbelted drivers
would be saved, for a total of 2,302 lives saved. This is a net figure,
i.e., it accounts for the possibility of 25 drivers being fatally
injured annually by an air bag. Given that the average annual rate of
driver fatalities for the last five years appears to be three, and that
the annual rate does not appear to be increasing, the projected figure
of 25 may be somewhat overstated.
The potential number of lives saved by passenger air bags is much
smaller than driver air bags primarily because the passenger seat is
occupied much less frequently than the driver seat. If all passenger
cars and light trucks had current passenger air bags, the agency
estimates that 223 belted and 491 unbelted passengers aged 13 and above
would be saved annually, for a total of 714 lives.
However, this figure of 714 would be partially offset by air bag-
related fatalities involving children 12 and under. If current rates of
child fatalities were experienced in an all-air-bag fleet, 128 children
would be fatally injured by air bags annually, again assuming no
technological improvements, changes to air bags, or behavioral changes
by vehicle operators (e.g., ensuring that any children placed in the
front seat properly use occupant restraints or, preferably, placing
children in the rear seat). The figure of 128 includes 90 forward-
facing children, most of whom would be unbelted, and 38 infants in
rear-facing child restraints.
NHTSA emphasizes that this and the other rulemaking proceedings and
related efforts are intended to ensure that risks of adverse side
effects of air bags are reduced so that these theoretically projected
air bag fatalities do not materialize, while the potential benefits of
air bags are retained, to the maximum extent possible. Thus, the agency
anticipates, e.g., that these other actions will result in proper use
of restraints by increased numbers of people and that the number of
children fatally injured would not be so high as 128. However, the
agency does not have a basis for estimating the exact effect. Further,
NHTSA recognizes that to the extent that one countermeasure is
effective, the potential benefits of another countermeasure could be
reduced. The Preliminary Regulatory Evaluation (PRE) for this
rulemaking gives an illustrative example of the effect that labeling
could have in reducing the benefits of depowering if the labeling were
10 percent effective in inducing more parents to place their young
children in the rear seat. (See page IV-54.) Likewise, a countermeasure
may reduce the potential disbenefits of another countermeasure. To the
extent that belt use is increased, the potential disbenefits of
depowering for unbelted occupants would be reduced. NHTSA solicits
suggestions for how it can attempt to quantify the interaction between
its various initiatives for
[[Page 813]]
increasing belt use and decreasing the adverse side effects of air
bags.
Projected Annual Lives Saved by and Fatalities Due to Air Bags
11
---------------------------------------------------------------------------
\11\ This projection is based on the assumption that all
passenger cars and light trucks on the road have driver and
passenger air bags. It does not take into consideration the impact
of this proposal or any of the other agency actions described in the
Overview and Summary section above.
Passenger Cars and Light Trucks
------------------------------------------------------------------------
Right front
Drivers passengers Total
------------------------------------------------------------------------
Lives Saved.......................... 2,327 714 3,041
Fatalities........................... 25 128 153
------------------------------------------------------------------------
III. Search for Solutions
Over the last five years, NHTSA has taken a variety of steps to
alert the public to the dangers posed by air bags to children and to
explore measures for reducing and even eliminating those dangers. The
steps taken in 1991-1995 were recounted in an NPRM published by the
agency on August 6, 1996. 61 Fed. Reg. 40784.
In the August 1996 NPRM, the agency proposed several amendments to
Standard No. 208, Occupant Crash Protection, and Standard No. 213,
Child Restraint Systems, to reduce the adverse effects of air bags,
especially those on children. The agency explained that eventually,
either through market forces or government regulation, it expects
``smart'' passenger air bags to be installed in passenger cars and
light trucks to mitigate these adverse effects. NHTSA indicated that,
for purposes of the NPRM, it considered smart passenger air bags to
include any system that automatically prevents an air bag from injuring
the two groups of children that experience has shown to be at special
risk from air bags: infants in rear-facing child seats, and children
who are out-of-position (because they are unbelted or improperly
belted) when the air bag deploys.
NHTSA proposed that vehicles lacking smart passenger air bags would
be required to have new, attention-getting warning labels and permitted
to have a manual cutoff switch for the passenger air bag. By limiting
the labeling requirement to vehicles without smart passenger air bags,
NHTSA hoped to encourage the introduction of the next generation of air
bags as soon as possible. NHTSA proposed to define smart air bags
broadly to give manufacturers flexibility in making design choices. The
agency requested comments concerning whether it should require
installation of smart air bags and, if so, on what date such a
requirement should become effective. NHTSA also requested comments on
whether it should, as an alternative, set a time limit on the provision
permitting manual cutoff switches for passenger air bags in order to
assure the timely introduction of smart passenger air bags. Finally,
the agency proposed to require rear-facing child seats to bear new,
enhanced warning labels. In a section in the August 1996 NPRM titled
``Future Agency Considerations,'' the agency also provided a discussion
of possible technological changes to address the forcefulness of air
bag deployment, ongoing agency efforts to evaluate the effects of such
changes, and possible future agency regulatory actions.
C. Recent Petitions for Rulemaking
Two weeks before the agency published its NPRM, the Parents'
Coalition for Air Bag Warnings submitted a petition requesting the
agency to commence a rulemaking proceeding to require that the
following warning label be placed on dashboard of vehicles with
passenger air bags:
``WARNING: DO NOT SEAT CHILDREN IN THE FRONT PASSENGER SEAT. AIR
BAG DEPLOYMENT CAN CAUSE SERIOUS INJURY OR DEATH TO CHILDREN.''
After the agency's publication of the August 1996 NPRM, the
American Automobile Manufacturers Association (AAMA) submitted a
petition for rulemaking requesting that NHTSA immediately announce, by
means of a ``direct final rule,'' an amendment to Standard No. 208 to
replace the current 30 mph unrestrained dummy barrier crash test
requirement with a sled test protocol incorporating a 143 millisecond
standardized crash pulse. The petitioner contended that the standard's
current requirement ``directly dictates the level of the air bag's
inflator power and it is the level of inflator power that unnecessarily
increases the risk of injury to vehicle occupants during air bag
deployment.'' AAMA also requested that the agency separately issue a
notice of proposed rulemaking to propose requirements to improve the
safety of drivers and passengers who are extremely close to the air bag
at the time of deployment, based on the latest International Standards
Organization (ISO) test practices. AAMA recommended the use of the
Hybrid III small female dummy in the driver position and appropriate
child dummy in the passenger position.
On September 1, 1996, Ms. Anita Glass Lindsey petitioned the agency
to commence rulemaking to specify the use of a test dummy representing
a 5th percentile female 12 in testing the performance of safety
belts and air bags. Currently, Standard No. 208 specifies the use of
only a 50th percentile male test dummy. 13
---------------------------------------------------------------------------
\12\ A 5th percentile Hybrid III dummy has a standing height of
5 feet and a weight of 110 pounds.
\13\ A 50th percentile Hybrid III dummy has a standing height of
5 feet, 8 inches and a weight of 172 pounds.
---------------------------------------------------------------------------
On September 17, 1996, the National Transportation Safety Board
(NTSB) issued a number of safety recommendations to NHTSA for reducing
the problem of child fatalities caused by air bags. These
recommendations are as follows:
1. Immediately evaluate passenger air bags based on all available
sources, including NHTSA's recent crash testing, and then publicize the
findings and modify performance and testing requirements, as
appropriate, based on the findings of the evaluation.
2. Immediately revise Federal Motor Vehicle Safety Standard 208,
Occupant Crash Protection, to establish performance requirements for
passenger air bags based on testing procedures that reflect actual
accident environments, including pre-impact braking, out-of-position
child occupants (belted and unbelted), properly positioned belted child
occupants, and with the seat track in the forward-most position.
3. Evaluate the effect of higher deployment thresholds for
passenger air bags in combination with the recommended changes in air
bag performance certification testing, and
[[Page 814]]
then modify the deployment thresholds based on the findings of the
evaluation.
4. Establish a timetable to implement intelligent air bag
technology that will moderate or prevent the air bag from deployment if
full deployment would pose an injury hazard to a belted or unbelted
occupant in the right front seating position, such as a child who is
seated too close to the instrument panel, a child who moves forward
because of pre-impact braking, or a child who is restrained in a rear-
facing child restraint system.
5. Determine the feasibility of applying technical solutions to
vehicles not covered by NHTSA's proposed rulemaking of August 1, 1996,
to prevent air bag-induced injuries to children in the passenger
position.
On November 8, 1996, the Center for Auto Safety (CFAS) petitioned
the agency to amend Standard No. 208 to specify that a vehicle's air
bags must not deploy in a crash if the vehicle's change of velocity is
less than 12 mph. CFAS noted that many of the crashes resulting in air
bag fatalities, especially those of children, involved very low changes
in vehicle velocity. CFAS also petitioned the agency to institute
investigations of several vehicle models for alleged defects related to
air bag deployment.
On November 13, 1996, the AAMA submitted a letter that modified the
proposal in its August 1996 petition for rulemaking. In place of the
143 millisecond standardized crash pulse, AAMA requested a sled test
protocol incorporating a 125 millisecond standardized crash pulse.
Finally, on November 20, 1996, CFAS and Public Citizen petitioned
the agency to begin rulemaking to require dual inflation air bags.
These bags would inflate more slowly, and thus less aggressively, than
current air bags in low-speed crashes. In higher-speed crashes, they
would inflate at the same rate as current air bags. The petitioners
assert that their proposal is the best solution in the near future and
is superior to depowering, since depowering involves ``some trade-off
in safety protection and will not add significant protection for
unrestrained children.''
IV. Overview of Comprehensive NHTSA Plan for Addressing Problem
NHTSA is implementing a comprehensive plan of rulemaking and other
actions (e.g., primary enforcement of State safety belt use laws)
addressing the adverse effects of air bags. As part of that plan, NHTSA
is issuing three separate, but related, notices today. Each notice is
intended to ensure that some or all of the risks are reduced, and
benefits retained, to the maximum extent possible. They provide
immediate and/or interim solutions to the problem. A later notice, a
proposal to require smart air bags, would provide a permanent solution.
In this notice, NHTSA is proposing to temporarily amend the
agency's occupant crash protection standard to help reduce the
fatalities and injuries that current air bags are causing in relatively
low speed crashes to small, but growing numbers of children, and
occasionally to adults. Based on agency research and analysis regarding
the optimal range of air bag depowering, the agency has tentatively
concluded that an average depowering of 20 to 35 percent would reduce
the risk of fatalities in low speed crashes, while substantially
preserving the life-saving capabilities of air bags in higher speed
crashes.
The agency is considering the adoption of either, or both, of two
different approaches that would permit or facilitate an approximate 20
to 35 percent average depowering of current air bags. One approach
would be to temporarily reduce the stringency of the chest acceleration
requirement that an unbelted dummy must meet in a crash test at speeds
up to 30 mph. The other approach would be to temporarily adopt the
AAMA's modified proposal for a sled test protocol incorporating a 125
millisecond standardized crash pulse.
NHTSA is seeking comments and information concerning the relative
desirability of these two approaches, including supporting data from
industry with respect to the sled test. It is also requesting comments
on the appropriate duration of such a temporary amendment. NHTSA
anticipates that it would remain in effect for both the passenger and
driver seating positions until smart air bags are installed pursuant to
a mandated phase-in schedule, which will be the subject of a separate
rulemaking proceeding. Finally, comments are sought on whether the same
or different requirements should apply to the passenger and driver
positions.
The other rulemaking actions addressing the adverse side effects of
air bags are as follows:
Based on the August 1996 NPRM, the agency issued on
November 22, 1996, a final rule amending Standards No. 208 and No. 213
to require improved labeling on new vehicles and child restraints to
better ensure that drivers and other occupants are aware of the dangers
posed by passenger air bags to children. The labeling places particular
emphasis on placing rear-facing infant restraints in the rear seats of
vehicles with operational passenger air bags. 61 FR 60206; November 27,
1996. The new labels are required on vehicles not equipped with smart
passenger air bags beginning February 25, 1997, and on child restraints
beginning May 27, 1997.
Based on the same NPRM, the agency is issuing a final rule
extending until September 1, 2000, a provision in Standard No. 208
permitting vehicle manufacturers to offer manual cutoff switches for
the passenger air bag for new vehicles without rear seats or with rear
seats that are too small to accommodate rear-facing infant restraints.
The agency also is issuing an NPRM proposing to permit
motor vehicle dealers and repair businesses to deactivate, upon the
request of consumers, driver and passenger air bags that do not meet
the agency's criteria for smart air bags. Final action is expected in
early 1997.
In addition to these actions, NHTSA will issue a separate
supplemental NPRM (SNPRM) to require a phasing-in of smart air bags,
beginning on September 1, 1998, and to establish performance
requirements for those air bags. The proposal will be issued in early
1997.
The next two tables summarize the rulemaking actions included in
the agency's comprehensive program to address these air bag problems:
[[Page 815]]
Actions Addressing Problems Associated With Passenger Air Bags
----------------------------------------------------------------------------------------------------------------
Vehicles produced in next Vehicles produced
Existing vehicles several model years thereafter
----------------------------------------------------------------------------------------------------------------
Passenger air bags.... Labels. New, attention- Labels. Final rule requiring Smart air bags. NPRM
getting labels focusing on new, attention-getting proposing to phase in
dangers of air bags to labels focusing on dangers requirement for smart air
children, to be mailed by of air bags to children, in bags.
vehicle manufacturers to vehicles whose passenger
owners of existing air bag air bag doesn't qualify as
vehicles. a smart air bag, and on
child seats.
Deactivation. Proposal to Cutoff switches. Final rule
allow deactivation of extending until Sept. 1,
passenger air bag that 2000, provision allowing
doesn't have cutoff switch cutoff switch for vehicles
and doesn't qualify as a (a) which lack a back seat
smart air bag. that can accommodate rear-
facing infant seats, and
(b) whose passenger air bag
doesn't qualify as a smart
air bag.
Deactivation. Proposal to
allow deactivation of
passenger air bag that
doesn't have cutoff switch
and doesn't qualify as a
smart air bag.
Depowering. Proposal to
temporarily allow
depowering of passenger air
bags that don't qualify as
smart air bags.
Driver air bags....... Labeling. New, attention- Labeling. Final rule Smart air bags. NPRM
getting labels urging all requiring new labels urging proposing to phase in
occupants to use their all occupants to use their requirement for smart air
safety belts and sit as far safety belts and sit as far bags.
back as possible to be back as possible.
mailed by vehicle
manufacturers to owners of
existing air bag vehicles.
Deactivation. Proposal to Deactivation. Proposal to
allow deactivation of allow deactivation of
driver air bags. driver air bags that don't
qualify as smart air bags.
Depowering. Proposal to
temporarily allow
depowering of driver air
bags that don't qualify as
smart air bags.
----------------------------------------------------------------------------------------------------------------
In addition to these actions, the agency is participating with
automobile manufacturers, air bag suppliers, insurance companies and
safety organizations in a coalition effort to address the adverse
effects of air bags by increasing the use of safety belts and child
seats. Substantial benefits could be obtained from achieving higher
safety belt use rates. If the safety belt use rate were 75 percent in
potentially fatal crashes instead of the current level of 52.6 percent,
an additional 4,000 lives would be saved annually.
The coalition has a three-point program that seeks to educate the
public about safety belt and child seat use, work with state and local
officials to improve enforcement of safety belt and child seat use laws
and seek the enactment of ``primary'' safety belt use laws. In States
with ``secondary'' safety belt use laws, law enforcement officials are
hampered in their ability to enforce the requirement to use safety
belts because their inability to stop and ticket motorists for the sole
reason of the motorists' failure to use their safety belts. A motorist
may be ticketed by an official for such failure only if the official
has a separate basis for stopping the motorist, such as the violation
of a separate traffic law.
A 1995 NHTSA analysis of FARS data on restraint use among fatally
injured motor vehicle occupants from 1983 to 1994 indicates that
primary enforcement is the most important aspect of a safety belt use
law affecting the rate of safety belt use. For virtually all states
with a primary enforcement law, statistically significant increases
associated with the presence of such a law were detected using several
different methods. The analysis suggests that the increase in use rates
attributable to the enactment of a use law can be estimated to be (on
the average) at least 25 percentage points, while the additional
increase attributable to primary enforcement of the law is at least 15
additional percentage points. These increases in safety belt use
translate into an estimated 12.6 percent decrease in fatalities in a
state that enacts a safety belt use law, and an additional 5.9 percent
decline in fatalities in a state that authorizes primary enforcement of
the law.
State data support these findings. On average, states with a
primary safety belt law have usage rates that are 10-15 percentage
points higher than states with secondary laws. In California and
Louisiana, states which recently upgraded their laws to allow for
primary enforcement, safety belt usage increased by 13 and 17
percentage points, respectively.
V. Depowering Air Bags
A. Results of NHTSA Test Program
To determine whether current air bags can be depowered to a degree
that makes a significant contribution to reducing the risk of serious
or fatal injury to occupants, especially children, without substantial
loss of protection for teenagers and adults, the agency initiated the
research testing and analysis program discussed in the August 1996
NPRM. NHTSA explained:
The agency has initiated a research testing and analysis program *
* * at the Vehicle Research and Test Center, the agency's in-house
laboratory in Ohio. The program's objectives are to:
Assess the performance of air bag systems in current
production vehicles in particular crash conditions, including the
effects on out-of-position children.
Assess the level of improvement possible in out-of-
position performance from changes to existing air bag components,
including downloaded air bags, as well as newly developed pre-
production systems.
Provide visibility for air bag-related technology, thus
promoting the rapid adoption of newer technologies that will
[[Page 816]]
help solve the out-of-position occupant injury problem.
The immediate focus of the program is on the passenger out-of-
position problem as related to children. Several vehicle models have
been selected based upon field accident investigations and air bag
design characteristics. Both domestic and foreign vehicles are included
in the selection. The test conditions include four different child
positions similar to those recommended by ISO [International Standards
Organization], and represent worst case occurrences. These tests will
provide ``baseline'' performance of air bag systems when a child is an
out-of-position occupant.
NHTSA is inviting vehicle manufacturers and air bag and component
suppliers to provide state-of-the-art air bag systems. Systems that
show significant improvements over baseline performance for out-of-
position children will also be tested with adult-sized dummies in full-
scale crash conditions required in Federal standards.
The test program will also address other aspects of air bag safety
following the out-of-position child study. These include out-of-
position driver tests, vehicle crash sensor testing, and testing of
advanced air bag systems. The out-of-position driver testing will focus
on small-sized female occupants who are sometimes injured due to the
close proximity to the steering-wheel air bag system. Testing will
continue into fiscal year 1997.
(61 FR 40784, at 40799; August 6, 1996.)
NHTSA has now tested the depowered air bags solicited from the
vehicle manufacturers. The air bags had been depowered through the
removal of certain amounts of propellant. While some of the air bags
were depowered up to 60 percent, most of them were depowered an average
of approximately 20 to 35 percent. However, their design (e.g., folding
patterns and venting) had not been optimized for the reduced levels of
power. As noted below, the agency believes optimization of the tested
air bags would have significantly enhanced their performance.
NHTSA tested baseline air bags (i.e., air bags of current design)
and depowered air bags on the passenger side in three different
vehicles, and on the driver side in one vehicle.14 NHTSA conducted
these tests using modified versions of recommended test procedures
formally adopted and issued in early 1996 by the ISO for evaluating
child restraint system interactions (ISO TR 14645) and out-of-position
vehicle occupant interactions (ISO TR 10982) with deploying air bags.
For the passenger air bags, the agency conducted various tests using
out-of-position three-year-old and six-year-old child dummies and
normally-positioned, belted and unbelted 50th percentile male
dummies.15 For the driver air bags, the agency conducted various
tests using out-of-position 5th percentile female dummies and normally-
positioned, belted and unbelted 50th percentile male dummies. The
agency also used computer-assisted mathematical modeling in an attempt
to assess the effects of depowering on the forces experienced by
occupants in air bag deployments.
---------------------------------------------------------------------------
\14\ The passenger air bag testing began in February 1996. The
testing of passenger air bags to estimate the effects of depowering
was completed in September. However, the testing of advanced
passenger air bag designs and test conditions continues. Testing of
driver air bags was conducted from May to September of this year.
More tests of driver air bags are planned for the future.
\15\ NHTSA did not conduct tests to determine the effects of the
depowered air bags on an infant dummy (i.e., nine-month-old dummy)
in rear- facing child restraints because the design of the depowered
bags would have precluded obtaining meaningful measurements of those
effects. Since all of the vehicles had top-mounted air bags (i.e.,
on top of the dashboard), the air bags would have tended to deploy
above the child restraints instead of directly impacting them. This
assessment appears consistent with the near total absence of top-
mounted air bags from the list of air bags involved in the fatal
injury of infants. None of the nine air bags was mid-mounted.
---------------------------------------------------------------------------
The results of the agency's analysis of this testing, as well as
other available information, are included in the PRE. Portions of the
PRE are summarized below.
B. Effects of Depowering and Optimizing
Overview. The agency's testing and other available information
16 indicated that depowering by an average of 20 to 35 percent
substantially reduced injury measures for persons close to the air bag,
especially out-of-position children, while producing only small
increases in injury measures for adult dummies. In the agency's
testing, depowering more than 35 percent resulted in more substantial
increases in adult dummy injury measures with a large additional
reduction in out-of-position child dummy injury measures for only the
more aggressive air bags. Thus, it appears that depowering at levels
more than an average of 35 percent could result in losing a significant
portion of the benefits being provided by air bags without a
commensurate reduction in child injury risk. (However, it is possible
that some of today's air bags are so aggressive that they could, if
optimized, be depowered by more than 35 percent without substantial
losses in adult benefits.)
---------------------------------------------------------------------------
\16\ Among the other items of information were the results of
testing performed by AAMA using out-of-position dummies representing
a six-year-old child, a 5th percentile female and a 50th percentile
male.
---------------------------------------------------------------------------
The reductions in injury measures achieved by depowering an average
of 20-35 percent would contribute significantly to solving the problem
created by overly aggressive air bags.17 While this average level
of depowering would not eliminate all of the risk of serious injury to
all persons currently at risk, it would eliminate much of the risk. The
agency's other rulemaking actions would reduce the residual risk.
---------------------------------------------------------------------------
\17\ The actual amount that the air bag in each specific vehicle
model would need to be depowered to achieve these benefits would
vary depending on the aggressivity of its air bag system. The least
aggressive air bags might need less than 20 to 35 percent
depowering, while the most aggressive ones might need more, as much
as 60 percent.
---------------------------------------------------------------------------
As noted above, the tested air bags were depowered, but not
optimized. Had they been optimized, the injury measures for belted
passengers would likely have decreased even more and those for belted
drivers would likely have improved. Thus, they would have offered
increased safety for belted occupants.18
---------------------------------------------------------------------------
\18\ The agency's belief that depowered air bags will provide
increased benefits to real world occupants compared to current air
bags is based in part on actual crash data regarding the performance
of air bags in an Australian passenger car, the Holden Commodore,
which is described below.
---------------------------------------------------------------------------
Summary of Effects of Depowering on Air Bag-Related Fatalities for
Particular At-Risk Occupant Groups
The ability of depowering to prevent air bag fatalities to
occupants would vary depending on a number of factors, especially the
location and belt use of the occupant. As shown in testing by the
agency of passenger air bags, the forces exerted by a deploying air bag
generally decrease as a function of increasing distance from the air
bag module. Although the surface of an expanding air bag in its initial
moments of inflation is potentially lethal, it rapidly changes within
inches into an injury-preventing and life-saving surface as it inflates
and moves away from its storage location. Thus, the farther away an
occupant is from an air bag as it starts to inflate, the better off
that occupant will be. While this is true for depowered as well as
current air bags, depowering can significantly reduce the size of the
zone within which serious injury is possible or likely.
Passengers. The at-risk groups are infants and young children.
Properly belted, forward-facing children who are on a vehicle seat
moved all the way back, should be at essentially no risk from a
deploying, depowered air bag,
[[Page 817]]
even if they are leaning forward while belted. Moderately out-of
position, forward-facing children would receive substantial benefits.
Severely out-of-position, completely unbelted forward-facing children
would receive some benefits. Given their proximity to the air bag,
infants in rear-facing child restraints would likely receive only
small, unquantifiable benefits from depowered air bags.19
---------------------------------------------------------------------------
\19\ As the agency has emphasized in numerous contexts, infants
in rear-facing child restraints should NEVER be placed in the front
seat of a vehicle with an operational passenger air bag.
---------------------------------------------------------------------------
Drivers. To the extent that there is an at-risk group, it is short-
statured women. Short, belted drivers on a vehicle seat moved as far
back as their stature permits would receive substantial benefits,
particularly with respect to neck injuries. They are not likely to move
as far forward as unbelted drivers during pre-crash braking and during
the initial stages of a crash. Benefits for unbelted drivers on a
vehicle seat moved all the way forward would depend on the drivers'
proximity to the air bag at the time of deployment. If they are at
least two or three inches away at the time of deployment, they should
receive some benefits from depowering with respect to chest and head
injuries. Depowering should help all drivers with respect to arm
injuries.
Overall Effects of Depowering. The PRE estimates the potential
overall effects of depowering on all forward-facing children, teenage
and adult occupants under the two alternative proposals, the 80 g
alternative and the generic sled test alternative. Both proposals would
produce a mixture of benefits and disbenefits, with the benefits
primarily accruing to children and belted teenage and adult occupants,
and the disbenefits primarily accruing to unbelted teenage and adult
occupants.
The magnitude of the benefits and disbenefits are estimated in the
PRE by two different methods. Method One includes only fatalities,
while Method Two includes fatalities and serious injuries. The results
of Method One, which produces slightly smaller upper end values for
lives saved and for foregone savings of lives, are discussed below.
1. Passenger Air Bags
Child Passengers. Older, Forward-Facing Children. Depowering could
prevent a significant number of the 90 annual fatalities projected
above for forward-facing children 20 in an all air bag fleet for
passenger cars and LTV's. The PRE estimates that 39 of the projected 90
fatalities could be prevented by depowering air bags by an average of
20 to 35 percent. This includes all of the lap and shoulder belted
children who might otherwise be fatally injured and most of the
moderately out-of-position children.21 With the additional
depowering possible under the generic sled alternative,22 up to 83
of the projected 90 fatalities could be prevented since more of the
severely out-of-position children could be benefited. Thus, depowering
would make it safe, from the standpoint of the air bag, to place a
child in the front seat when necessary, assuming that the child was
properly restrained in a vehicle seat that was moved all the way back.
The agency emphasizes that, even in the absence of an air bag, the rear
seat is a significantly safer place for children to ride than the front
seat.
---------------------------------------------------------------------------
\20\ As noted above, the age range of the forward-facing
children fatally injured during air bag deployments is one to nine
years old.
\21\ These estimated savings are based on the significant
reductions in neck injury criteria values observed in all three
tested vehicles. These values are the most important ones for
estimating fatality risk, since neck injury has been the typical
fatal injury mechanism for these children.
\22\ As reflected below in the discussion of the alternative
proposals, it is assumed in the PRE that the depowering of any air
bags more than 35 percent is achievable only under the second
alternative proposal (i.e., AAMA's generic sled pulse) since it
appears that HIC or other injury criteria could not be met under the
first alternative proposal (80 g limit on chest g's in the unbelted
30 mph test) with air bag systems depowered significantly above 35
percent.
---------------------------------------------------------------------------
Rear-Facing Children (Infants). Based on HIC reductions achieved in
testing the effects of depowered air bags on three- and six-year-old
dummies, the agency believes that depowering could prevent the death of
some of the 38 projected fatalities of infants. However, for reasons
explained below, the agency cannot quantify those savings.
As noted above, the agency did not perform any testing of depowered
air bags with infants in rear-facing infant seats. Thus, the agency
does not have any baseline versus depowered air bag data for rear-
facing child restraints to estimate the potential benefits of
depowering. However, HIC data from the testing of severely out-of-
position three- and six-year-old children indicate that HIC was
substantially reduced by depowering, but not typically below the
assumed infant injury reference value of 500 HIC. HIC data are relevant
because the primary cause of rear-facing infant fatalities in air bag
deployments has been skull fractures. Since it is not possible at this
time to make appropriate adjustments to reflect greater susceptibility
of infants to fatal head injury, the HIC data for dummies representing
older children could not be used to estimate potential benefits of
depowering for infants. The agency has not made a specific, quantified
estimate because of its roughness and therefore its questionable value.
Teenage and Adult Passengers. Depowering air bags to an average of
20 to 35 percent would likely benefit belted teenage and adult
passengers on balance, but could necessitate foregoing the opportunity
to save some unbelted teenage and adult passengers.23 These
estimates are based on chest g measures because, as noted in the PRE,
chest g's are the most important measure for assessing the effects on
teenagers and adults, since chest g's appear to have a stronger
relationship to fatality risk than HIC. Further, the HIC increases due
to depowering in this range were not that significant.
---------------------------------------------------------------------------
\23\ As noted below, the occupants can essentially eliminate the
risk to them by the simple act of buckling their safety belts.
---------------------------------------------------------------------------
Belted Teenage and Adult Passengers. The agency's PRE assumes a 2.4
g decrease in chest g's for belted passengers under the 80 g
alternative, using an air bag that had been depowered but not
optimized. This assumption was based on test results showing a 2.4 g
decrease in chest g's, although mathematical modeling predicted almost
no change for belted passengers. Under the generic sled test
alternative, a decrease of 1.9 chest g's is assumed, based on
mathematical modeling. Both decreases would result in saving additional
lives compared to current air bag designs.
As noted above, NHTSA believes that a greater decrease in chest
g's, and therefore a greater increase in life-saving potential, would
have occurred had the air bags not only been depowered, but also
optimized for the new power level. The depowered air bags tested by
NHTSA were not optimized in ways that would likely have reduced the
chest g's even more. For example, the air bags were not optimized with
respect to their venting rates.
The agency believes that it is unlikely that the vehicle
manufacturers would depower their air bags without also optimizing
them. NHTSA believes that the manufacturers would, out of reasonable
prudence, do both.
This is significant because real world data from Australia
regarding the performance of depowered driver air bags optimized for
belted occupants suggests that depowering and
[[Page 818]]
optimizing current U.S. air bags could significantly increase the
effectiveness of air bags for belted occupants and lead to large
savings of lives. Those data, drawn from crashes involving Holden
passenger cars,24 indicate that air bags with lap/shoulder belts
reduced AIS 2+ injuries to drivers by 39 percent compared to lap/
shoulder belts alone. By comparison, current U.S. air bags have an AIS
2+ effectiveness of 22 percent when lap and shoulder belts are worn.
According to the PRE:
\24\ The Holden passenger cars have depowered air bags that have
a ``no-fire'' threshold of 12.4 mph and an ``always-fire'' threshold
of 17.4 mph. While thresholds vary for U.S. air bags, a typical one
has a ``no-fire'' threshold of 9 mph and an ``always-fire''
threshold of 14 mph.
---------------------------------------------------------------------------
The air bag systems in the Commodore are designed to deploy as
unaggressively as possible while still providing the necessary
protection to occupants of different size, weight and sex who will
be potentially involved in a variety of collisions. Great efforts
have been taken in the development of the inflators and cushions to
ensure they present as little risk as possible to occupants during
inflation. Since the air bags have been designed to operate in
conjunction with the safety belts, they are only required to
decelerate the occupant's head and upper torso, as the primary load
path is through the belts. This is fundamentally different from many
other air bag designs, especially those used to protect unrestrained
occupants. Systems optimized to protect unrestrained occupants
typically utilize high-performance inflators in conjunction with
cushions with low venting rates. This combination ensures that the
air bags are sufficiently stiff to decelerate unbelted occupants.
(Page V-1)
If such increased effectiveness could be obtained for belted
passengers, it would offset a significant portion of the potential
adverse impact of depowering estimated below on unbelted passengers. As
discussed in the PRE, current NHTSA analyses indicate that air bags in
this country are 8.5 percent effective in reducing belted fatalities.
If the relationship in overall effectiveness of the Holden bag to the
U.S. air bags for AIS 2+ injuries were the same for fatalities, the
effectiveness of U.S. air bags for preventing fatalities to belted
occupants could be as high as 15 percent. If depowering and optimizing
U.S. air bags increased their effectiveness to that level, large
savings in the lives of belted occupants could result.
The agency seeks comments, on a model-by-model basis, if possible,
from the vehicle manufacturers on what specific optimization measures
they would adopt and on whether such optimization could be accomplished
and incorporated in production air bags within the time frame projected
by the vehicle industry for introduction of the depowered air bags. As
noted below, AAMA projected that its members could begin introducing
depowered air bags within 6-9 months and complete the process across
their fleets within a year after those first introductions. NHTSA
solicits comments as to what effect, if any, efforts to optimize these
air bags prior to their introduction might have on the schedule for
their introduction. Comment is also sought whether adoption of the sled
test suggested by AAMA would enable vehicle manufacturers to accelerate
the introduction of optimized and depowered air bags. The agency also
requests comments on what effects, if any, the optimization of air bag
performance for the benefit of belted occupants would have on air bag
effectiveness for unbelted occupants. Finally, comment is sought on the
Holden data and the reasonableness of the assumption in the PRE that
effectiveness of U.S. air bags in reducing belted fatalities could be
raised substantially in the next several years through depowering and
optimizing.
Unbelted Teenage and Adult Passengers. Depowering could necessitate
foregoing the opportunity to save a significant number of unbelted
teenagers and adults. The PRE estimates that, as a result of a
significant increase in chest g's associated with depowering by an
average of 20 to 35 percent under the 80 g alternative, there could be
a reduction of between 86 and 280 unbelted passengers who would have
otherwise been saved by current air bags. This reduction reflects an
assumed average increase of 11 g's in the chest g's for unbelted
passengers as a result of depowering, but not optimizing air bags. This
assumption was based on limited test results showing an 11 g increase
in chest g's at 30 mph. Mathematical modeling predicted a slightly
lower increase. With greater depowering under the generic sled test
alternative, it was assumed that chest g's would increase by 22 g's,
based on sled tests and mathematical modeling. That increase would
result in a potential loss of savings of 115 to 336 unbelted
passengers.
It should be noted, however, that AAMA does not anticipate such
losses. AAMA provided an estimate of the effects of depowering, based
on NASS data, a number of analytic assumptions, and sled/barrier test
results. That organization estimates the potential savings of 30 to 200
small adults per year due to increased effectiveness of passenger and
driver air bags for those persons and the potential loss of up to eight
large adults annually. The agency seeks comment from AAMA on how it
calculated those figures.
Further, to the extent that increased numbers of people use their
safety belts, the potential losses in savings of unbelted passengers
would not materialize. While increasing safety belt use would reduce
the benefits of depowering, by reducing the size of some groups (i.e.,
unbelted children and drivers) vulnerable to air bag fatalities, there
would be very large increases in the number of people saved by occupant
restraints of one type or another. As noted above, if the safety belt
use rate were 75 percent in potentially fatal crashes instead of the
current level of 52.6 percent, an additional 4,000 lives would be saved
annually. NHTSA plans to work vigorously with the States to increase
safety belt use through public education and authorizing primary
enforcement of safety belt use laws.
Safety Tradeoffs. NHTSA has carefully considered the potential
tradeoffs implicit in depowering passenger air bags. Given the wide
range of the above estimates concerning unbelted passengers, the agency
believes that the net effect of depowering on safety could be positive.
However, even if the net effect were negative, the agency believes that
the opportunity to save a significant number of children who would
otherwise be fatally injured by air bags justifies foregoing the
opportunity to save some unbelted passengers. There are several reasons
for this policy choice.
First, it is not acceptable that a safety device cause a
significant number of fatalities in circumstances in which fatal or
serious injuries would not otherwise occur. In making this statement,
the agency draws a distinction between air bags which are fatally
injuring young children in low speed crashes in which the other vehicle
occupants are uninjured, and other safety devices which may on occasion
unavoidably substitute one type of injury for another type that would
occur in their absence (safety belts are a good example).25 Those
fatalities are particularly unacceptable in light of the agency's
analysis showing that depowering air bags can significantly reduce the
number of children being fatally injured by air bags.
---------------------------------------------------------------------------
\25\ In severe collisions, safety belts can seriously bruise the
chest of an occupant or even cause rib fractures. However, the
restraining force of the belt would also likely prevent even more
serious chest or head injury from the occupant's striking the
interior components of the vehicle.
---------------------------------------------------------------------------
Second, it is also particularly unacceptable that the vehicle
occupants being fatally injured are young children, and that the number
of those deaths is
[[Page 819]]
steadily growing. In confronting the possibility of inevitable short-
term safety tradeoffs between young children and unbelted occupants
over 12 years of age, the agency believes that greater weight must be
placed on protecting young children. NHTSA has always given a high
priority to protecting children and accordingly has applied these
different cost-benefit considerations to its rulemaking affecting
children. The agency's activities related to school bus safety
standards are an example of this policy.
A major reason for giving priority to protecting young children is
that they are less mature than teenagers and adults and thus less able
to exercise independent judgment, assess the risks and take action to
improve their safety. The young children are more dependent on the
judgment and actions of other persons. The oldest of the 32 children
who have been fatally injured by an air bag was nine years old, and
most of the children have been much younger. Nineteen were four to
seven years old and nine were infants. Conversely, the unbelted
teenagers and adults who might not be saved as a result of depowering
can take action on their own to protect themselves by simply buckling
their safety belts as required by the laws of 49 States and the
District of Columbia.
Notwithstanding the justifications for making the safety tradeoffs,
NHTSA is concerned about them. It is because of the possibility of
disbenefits, especially for unbelted occupants, that the agency is
proposing to make only a temporary change in Standard No. 208 to permit
or facilitate the depowering of air bags. The agency will shortly issue
a proposal to require a phase-in of smart air bags. Requiring smart air
bags would not only enable the agency to make depowering a temporary
measure, but would also ensure that the problem of adverse effects from
air bags is fully addressed, and that air bags achieve their full
safety potential for protecting a wide variety of vehicle occupants
over an appropriate range of vehicle speeds.
2. Driver Air Bags
Analysis of the net effect of depowering driver air bags is more
difficult and therefore less precise largely because the agency has
conducted fewer tests of depowered driver air bags and because the test
results for the unbelted drivers are a mixture of small increases and
decreases in chest g's. Nevertheless, the agency believes that
depowering driver air bags would enhance safety. As noted above, belted
short drivers who move their seat as far back as their stature permits,
would benefit substantially from depowering. Belted drivers, in
general, should benefit as well since depowering appears to allow a
better ``tuning'' of the combined safety belt-air bag system for belted
occupants. Unbelted, out-of-position short drivers could receive some
benefit as well. As a result, there would be some reduction in the
projected figure of 25 driver fatalities per year.
Belted Drivers. Depowering alone increased the chest g's for belted
drivers in NHTSA's vehicle testing. Although the tests showed a 7 g
increase at 35 mpg, there appears to be no logical reason for such an
increase. In the same test, chest g's decreased for the belted
passenger dummy. Further, modeling suggested only a marginal increase
of 2 g. The PRE assumes a 2 g increase for belted drivers under the 80
g alternative. Under the generic sled test alternative, chest g's go up
or down at different speeds with the net result that there would be no
change in overall fatalities for depowered, but not optimized, air
bags.
As in the case of passenger air bags and belted passengers, the
agency believes that the data concerning the air bags in the Australian
Holden passenger car show that optimizing as well as depowering air
driver bags would produce a more favorable result for belted drivers
than the depowered air bags tested by NHTSA. Since most of the Holden
data related to driver air bags instead of passenger air bags, the
agency has good reason to be even more confident about the implications
of the Holden data for belted drivers in this country. With
optimization, the agency believes that, instead of an increase in chest
g's under the 80 g alternative or no change under the generic sled test
alternative, a decrease is likely. If depowering and optimizing U.S.
driver air bags increased their effectiveness to as much as 15 percent,
the savings would be 471 drivers.
Unbelted Drivers. Depowering by an average of 20 to 35 percent
under the 80 g alternative appears to slightly increase the chest g's
of unbelted drivers. It is believed that the energy absorbing steering
column is the reason that chest g's do not increase in proportion to
the amount of depowering. In vehicle tests with depowered air bags,
chest g's increased by 2 g at 30 mph, but decreased by almost 3 g's at
35 mph. The results of modeling were mixed also, but consistent with
the vehicle test results. Modeling predicted a slight increase at 30
mph and decrease at 35 mph. Since there was an increase at some speeds,
the PRE assumes a 2 g increase under the 80 g alternative. Based on
that increase, the PRE estimates a possible loss in savings of 9 to 41
unbelted drivers. Under the generic sled test alternative, the PRE
assumed a 10 g increase based on modeling. That increase suggests a
resulting loss of 221 to 650 unbelted drivers.
As noted above, there is reason to believe that these losses might
not occur. AAMA estimates the potential savings of 30 to 200 small
adults per year due to increased effectiveness of passenger and driver
air bags for those persons and the potential loss of up to eight large
adults annually. Further, to the extent that increased numbers of
people use their safety belts, the potential losses in savings of
unbelted passengers would not materialize. NHTSA plans to work
vigorously with the States to increase safety belt use through public
education and authorizing primary enforcement of safety belt use laws.
Arm Injuries. The agency believes that depowering would lead to a
significant reduction in driver arm injuries associated with air bag
deployments. Compared to MY 1994 vehicles, depowering air bags by an
average of 20 to 30 percent could reduce AIS 2-3 arm injuries from
25,006 to 16,254, a reduction of about 8,800 injuries.
Safety Tradeoffs. NHTSA has carefully considered the potential
tradeoffs implicit in depowering driver air bags. Despite the wide
range of the above estimates concerning unbelted drivers, the agency
believes that the net safety effect of depowering passenger air bags
could be positive instead of negative. Even if the net effect were
negative, the agency believes that the opportunity to avoid causing
fatal injuries to some drivers justifies foregoing the opportunity to
save more unbelted drivers. The reasons for this policy choice are
similar to those for depowering passenger air bags.
First, the principle of not affirmatively causing harm when harm
would not otherwise occur applies to all vehicle occupants. While it is
probably unavoidable that some safety devices may on occasion
substitute one type of injury for another type that would occur in
their absence, it is not acceptable that safety devices cause a
significant number of fatalities in circumstances in which fatal or
serious injury would not otherwise occur.
Second, the drivers who might lose benefits as a result of
depowering are unbelted drivers. They can protect themselves by taking
the simple step of buckling their safety belts as required by the laws
of 49 States and the District of Columbia.
[[Page 820]]
Nevertheless, as noted above, due to the possibility of adverse
safety tradeoffs, NHTSA is seeking to limit the duration of the
tradeoffs by proposing to make only a temporary change in Standard No.
208 to permit or facilitate the depowering of air bags. The agency's
planned proposal to require smart air bags would not only enable the
agency to make depowering a temporary measure should the adverse
tradeoffs actually materialize, but would also ensure that the problem
of adverse effects from air bags is fully addressed, and that air bags
achieve their full safety potential.
C. Alternative Proposals
The preceding sections of this notice discuss the benefits of
depowering passenger and driver air bags by various amounts, and the
net effects on safety. While the agency recognizes that depowering air
bags may result in some adverse safety tradeoffs, primarily to unbelted
teenage and adult occupants, it believes that depowering represents a
desirable temporary means of addressing the problem of fatalities and
injuries from air bags.
Having tentatively decided that depowering of air bags is
desirable, it is necessary for the agency to determine whether a
regulatory change is needed to permit this action and, if so, what the
most appropriate change would be.
Manufacturers have asserted that a regulatory change is needed
because if air bags were depowered to an appropriate extent,
manufacturers would be unable to certify that all of their vehicles
comply with Standard No. 208's unbelted test requirements.
As discussed in the PRE, the agency's testing shows that an average
20 to 35 percent depowering of passenger air bags would result in chest
g's for some vehicles approaching or slightly exceeding Standard No.
208's 60 g limit for the unbelted test. This indicates that a
regulatory change would be needed to permit this level of depowering
for these vehicles. The agency's limited data suggest that the
standard's other requirements would not preclude this level of
depowering, although the 1000 HIC limit would prevent significantly
higher levels of depowering.
NHTSA does not have data concerning whether a regulatory change
would be needed to permit 20 to 35 percent depowering of driver air
bags, but is requesting commenters to provide such data. As discussed
in the PRE, when driver air bags depowered to that extent were tested
by NHTSA at 30 mph, unbelted chest g's increased from 49 to 51. Ford
modeling for driver air bags shows similar results, with chest g's
rising by only 2 or 3 g's for belted and unbelted drivers. Available
NHTSA modeling shows variable results (some chest g's going up and
others down), but all were well within the standard at 30 mph. The
agency believes that energy absorbing steering columns explain why the
driver air bag can be depowered without significantly affecting chest
g's. However, the agency conducted only limited testing and did not
conduct any angle tests. The agency requests comments, including data,
concerning how depowering driver air bags by various percentages would
affect the manufacturers' ability to certify compliance with Standard
No. 208.
The agency is proposing the adoption of either, or both of two
potential changes as alternative temporary amendments to Standard No.
208: either increasing the current chest acceleration limit to 80 g's,
or replacing the unbelted crash test requirement with a sled test
protocol incorporating a standardized crash pulse. If the agency were
to adopt both of these changes, a manufacturer could select either
alternative at its option. However, a manufacturer could not mix the
two options, i.e., the 80 g chest acceleration limit would not apply in
the case of the generic sled test.
A discussion of each of the two alternative approaches being
proposed by the agency is presented in the next two sections.
1. Approach I--Temporary Change in Unbelted Chest Acceleration
Requirement
NHTSA believes that the simplest regulatory change would be to
amend the requirement which appears to be the factor limiting the
vehicle manufacturers' ability to depower current air bags by 20 to 35
percent. This points to reducing the stringency of the unbelted chest
acceleration requirement. The agency is proposing to increase the
current limit from 60 g's to 80 g's. However, the agency is requesting
comments on both higher and lower values, and could select a different
value for the final rule.
This alternative has other advantages in addition to its
simplicity. Occupant protection would continue to be measured in full-
scale vehicle tests, protection in impacts at a range of angles would
be ensured, and the other injury criteria would not change. The agency
notes that recent biomechanical data generated for NHTSA suggests that,
with respect to potential chest injuries, the human tolerance to
acceleration is higher for air bags than for belts, because the air bag
delivers a more broadly distributed, uniform loading to the chest than
does a safety belt. Therefore, an 80 g requirement for occupants
protected by air bags appears to be at least as protective as a 60 g
requirement for belted occupants.
The agency notes that amending the standard to allow chest
accelerations of 80 g's does not mean that chest g measurements in
crash tests would necessarily rise to that level. The agency's test
data suggest that while a change to 80 g's would be sufficient to
permit or facilitate 20 to 35 percent downloading, air bags with
progressively higher levels of downloading (beyond 20 to 35 percent)
are likely to exceed Standard No. 208's head injury criterion before
they exceed the 80 g requirement.
NHTSA also notes that the PRE's estimates of safety impacts for the
80 g alternative do not assume an increase to 80 g's, or to any
particular level below 80 g's. The estimates are instead based on the
agency's analysis of the effects of depowering air bags by 20 to 35
percent.
The agency's analysis assumes, based on limited vehicle testing,
that chest g's would rise by an average of approximately 11 g's for the
unbelted 50th percentile male. Since compliance data show that chest
g's for this test currently average about 43 g's, the assumed 11 g
increase means that the average would increase to about 54 g's for the
50th percentile male dummy.
NHTSA intends for any regulatory change to Standard No. 208 to
permit or facilitate quick depowering of air bags. In order to reduce
the leadtime for depowered air bags, the agency is proposing, as part
of its 80 g proposal, to establish a special two-year enforcement
policy for Standard No. 208's unbelted test requirements.
The agency recognizes that, under ordinary circumstances,
manufacturers making air bag design changes typically conduct extensive
testing to ensure that a vehicle will continue to meet the standard's
performance requirements at any particular level. They do so despite
the existence of various provisions of Standard No. 208 that provide
that ``a vehicle shall not be deemed to be in noncompliance with this
standard if its manufacturer establishes that it did not have reason to
know in the exercise of due care that such vehicle is not in conformity
with the requirement of this standard.'' See, e.g., S4.1.5.3.
While NHTSA generally considers some degree of testing to be
necessary to satisfy this ``due care'' requirement, under the proposed
two-year policy, the agency would consider engineering analyses
indicating that a vehicle will pass the unbelted test requirements with
a depowered air bag as sufficient during that period to establish that
the vehicle's
[[Page 821]]
manufacturer exercised due care to ensure that the vehicle conforms
with the requirement, even in the absence of confirming crash testing.
Of course, the agency would retain the right to enforce the
requirements of the standard if the noncompliance was due to quality
control deficiencies or other manufacturing problems. This policy would
be reflected in an appendix to the standard.
2. Approach II--Temporary Replacement of Unbelted Crash Test
Requirement With a Sled Test Protocol Incorporating a Standardized
Crash Pulse
In August 1996, AAMA submitted a petition for rulemaking
requesting, among other things, an immediate amendment to the
requirements for testing the ability of air bags to protect unbelted
occupants. The current requirement measures occupant protection in a
full scale crash test in which a vehicle, equipped with test dummies at
the outside front seating positions, is crashed into a barrier.
Specified injury criteria, measured on the test dummies, must be met in
barrier crashes at speeds up to 30 mph, and a range of angles up to 30
degrees off-center.
AAMA requested that this crash test requirement be replaced with a
sled test protocol. Under that protocol, all of a vehicle, or a portion
of the vehicle representing the interior, would be mounted on a sled.
The sled would be decelerated from 30 mph according to a standard
formula, called a crash pulse. There would not be an angle test, only a
direct frontal test.
NHTSA notes that sled tests can be used by researchers to simulate
what will happen to occupants in real world crashes. The crash pulse
for a given sled test is a major determinant of the stringency of the
test, and how representative the test is of how a particular vehicle
will perform in particular kinds of real world crashes.
To explain further, the term ``crash pulse'' is defined as the
acceleration-time history of the occupant compartment of a vehicle
during a crash. This is typically represented in terms of g's of
acceleration plotted against time in milliseconds (1/1000 second).
Generally speaking, the occupant undergoes greater forces due to
secondary collisions with the vehicle interior and restraint systems if
the crash pulse g's are higher at the peak, or the duration of the
crash pulse is shorter, which would lead to higher overall average g
levels.
The crash pulse experienced by a particular vehicle will obviously
differ substantially in different types of crashes, e.g., if the
vehicle crashes into a rigid stone wall vs. a stack of hay. Similarly,
vehicles with different designs typically experience substantially
different crash pulses in the same kind of crash, depending on such
things as the stiffness of the vehicle structure and amount of crush
space. Large cars typically have relatively mild crash pulses, while
small cars and utility vehicles typically have more severe crash
pulses.
Under AAMA's recommended amendment, the same crash pulse would be
used for all vehicles. The petitioner argued that the standard's
current test protocol ``directly dictates the level of the air bag's
inflator power and it is the level of inflator power that unnecessarily
increases the risk of injury to vehicle occupants during air bag
deployment.'' AAMA asserted that its recommended test protocol would
allow for lower powered inflators to be introduced into the market as
quickly as possible while maintaining air bag protection for all
occupants.
In its August 1996 petition, AAMA provided the parameters for its
recommended pulse along with a suggested mathematical formula, called a
sine pulse. The sine pulse suggested by AAMA is described by the
mathematical function: A=15 sin (t/143) Gs.
After examining the sled test protocol initially advocated by AAMA,
NHTSA concluded that the standardized sled pulse suggested in the
petition is representative of a very soft, or benign crash. Indeed, the
agency wondered whether the pulse were so benign that a vehicle could
meet the requirements for protecting an unbelted dummy without an air
bag.
To answer this question, NHTSA tested a 1993 Taurus according to
the sled test protocol recommended by AAMA, i.e., the 143 millisecond
(msec) sled pulse (15 g peak). The vehicle did not have a passenger air
bag. Although the vehicle had a driver air bag, it was deactivated so
that it would not deploy. Although protected by neither safety belts
nor air bags, neither of the dummies had responses that exceeded the
injury criteria specified in Standard No. 208.
In its November 13, 1996 letter, AAMA suggested that the agency use
a more severe crash pulse, 125 msec., which corresponds to 17.1 g. AAMA
also argued that the agency should consider injury measurements for the
neck in evaluating the crash pulse, rather than focusing solely on
whether vehicles without air bags could pass the current Standard No.
208 injury criteria (HIC, chest and femur loads) in a test using the
pulse. AAMA indicated that a vehicle could not meet appropriate neck
injury assessment reference values (IARV's) in a test using the pulse
without an air bag.
NHTSA notes that the revised AAMA recommended crash pulse is
similar to that experienced by a large car in a Standard No. 208 test,
but milder than that experienced by a typical small car, utility
vehicle, or light truck. The PRE provides additional information about
crash pulses.
In December 1996, NHTSA conducted several tests of a 1993 Taurus
according to the revised sled test protocol recommended by AAMA, i.e.,
125 msec, 17.1 g. The agency repeated the same test it had conducted
with the earlier pulse, i.e., a no-air-bag test with unbelted 50th
percentile male dummies. However, NHTSA also measured forces on the
neck so that it could make calculations relative to IARV's. The agency
also conducted tests with baseline and depowered air bags, and with
fifth percentile female dummies.
NHTSA was still reviewing data calculations for this new test
series as this notice was being completed. The agency expects to place
the data in the docket at, or shortly after, the time this notice is
published. NHTSA requests comments on what conclusions should be drawn
from the data and on how the results of the tests should be factored
into the agency's final decision concerning this proposal.
There are potential advantages and disadvantages to the approach of
using a standardized crash pulse representative of a large car as a
temporary means of addressing air bag fatalities to children. The
approach provides maximum flexibility to manufacturers in addressing
these fatalities. In its 1984 rulemaking establishing the automatic
protection requirements that were in effect until the implementation of
ISTEA, NHTSA recognized that technical problems existed in designing
air bags that would not pose a danger to unrestrained small children in
small cars. Because the crash pulse of small cars is much more severe
than that of large cars, more aggressive air bags are needed to meet
the standard's injury criteria. The agency stated:
Manufacturers claim that little development work has been done
with air bags for small (e.g., subcompact or smaller) cars and that
a particular problem in these vehicles is how to protect small
children, who are not properly restrained, from the more rapidly
deploying air cushion in such vehicles. The Department believes that
this problem can be mitigated and that technical
[[Page 822]]
solutions are available, as described in the FRIA. However, the lack
of experience in this area, as well as the lack of experience for
some companies in any form of air bag development, make the
Department reluctant to mandate across-the-board air bags. 49 Fed.
Reg. 29001, July 17, 1984; See July 11, 1984 FRIA, pp. III-7 to 11.
The AAMA recommended sled test approach would essentially permit
the auto manufacturers to use air bags for small cars and other
vehicles with severe crash pulses (e.g., utility vehicles and trucks)
that are similar to the ones they use for large cars. This would
eliminate some of the problems that exist in designing air bags for
these vehicles that are not aggressive to children, i.e., the risk of
aggressivity would be normalized for all vehicles.
Another advantage of a sled test approach is that it reduces the
time and cost of doing certification testing, since sled tests are less
destructive of the vehicle. Further, many more sled tests can be
conducted in the same time period, since the motor vehicle industry and
its suppliers have substantially greater capacity to conduct sled tests
than barrier tests.
The primary disadvantage of using a standardized crash pulse
representative of a large car is that the test will be less
representative of actual performance for small cars and other vehicles
with severe crash pulses, i.e., the test measures only air bag
performance and not total vehicle performance. The approach also
eliminates the effect of angle test requirements, which ensure
protection in frontal impacts that occur at a range of angles rather
than purely head-on. However, given that recent NHTSA analyses indicate
that current fatality reducing benefits of air bags drop off rapidly as
crashes diverge from direct ``head-on'' collisions, deleting the
requirement for meeting injury criteria in a 30 degree test might not
substantially degrade the ``real world'' benefits of air bags in such
crash configurations. (``Fatality Reduction by Air Bags, Analyses of
Accident Data through early 1996,'' August 1996 NHTSA Technical Report,
DOT HS 808 470) NHTSA requests comments on this issue.
As a practical matter, the AAMA recommended sled test approach
appears to permit more depowering than the 80 g approach. Under the 80
g approach, Standard No. 208's HIC requirement appears to preclude
depowering much beyond the 20 to 35 percent range. The agency does not
know how much depowering would be permitted by the AAMA approach, but
believes it could be considerably greater than 35 percent, at least for
vehicles that currently experience a severe crash pulse in the current
Standard No. 208 test. While this maximizes manufacturer flexibility in
addressing the fatalities to children, it also raises the possibility
of greater adverse safety tradeoffs, especially to unbelted teenage and
adult occupants.
In the context of a temporary amendment to Standard No. 208,
however, the agency believes it is important to distinguish between
what the manufacturers might technically be permitted to do and the
actions they would actually take in response to a regulatory change.
Because of the substantial differences among current air bags, it is
likely that very different levels of depowering are needed for
different air bags in order to significantly reduce the risk of child
fatalities. For some air bags, 10 percent depowering may be necessary;
for others, 60 percent depowering may be necessary.
Because the same standards apply to all vehicles, it is possible
that any regulatory change that would permit 60 percent depowering of
the most aggressive air bags would permit greater than optimal
depowering of other air bags. That does not mean, however, that
manufacturers would depower all air bags to the maximum extent
permitted by the amendment. Instead, the agency anticipates that the
manufacturers would only depower particular air bags to the extent
needed to address the child fatality problem, and preserve unbelted
occupant protection to the maximum extent possible.
As part of proposing the AAMA recommended sled test approach, the
agency is proposing to add neck injury criteria for the 50th percentile
male dummy. As indicated above, AAMA argued that the agency should
consider injury measurements for the neck in evaluating the crash
pulse. The source of the proposed neck criteria is ``Anthropomorphic
Dummies for Crash and Escape Systems,'' AGARD Conference Proceedings of
NATO, July 1996, AGARD-AR-330. A copy of the relevant pages is being
placed in the docket. The agency notes that GM uses the same neck
criteria for its IARVs. Data provided by AAMA indicate that, in
general, all of these neck criteria could not be met without an air
bag.
The proposed neck injury criteria represent peak values for very
short duration loading. Much lower loads can be tolerated for longer
duration loading. Time dependency criteria may need to be specified.
The agency solicits comments on this subject.
The agency is proposing a test procedure similar to that presented
in AAMA's petition. NHTSA notes that the proposed procedure specifies
that the vehicle, or ``a sufficient portion of the vehicle to be
representative of the vehicle structure,'' is mounted on the sled. The
agency requests comments on the practicality of conducting sled tests
with whole vehicles, and on whether the quoted language can be made
more objective.
NHTSA notes that AAMA included in its initial petition both a
recommended crash pulse and specified corridors for that pulse. The
agency believes that it is necessary to specify corridors in addition
to a specific pulse, because it is generally not possible to duplicate
exact pulses. Manufacturers would be required to certify that their
vehicles comply with the standard's performance requirements for all
tests within the specified corridors. The agency notes that AAMA has
not provided corridors for its revised crash pulse, and has written to
AAMA requesting it to provide a figure showing the mathematical
equation for the revised pulse, a graph of the pulse and corridors for
the pulse. This information will be docketed as soon as possible after
it is received by the agency. While the proposed regulatory text
specifies only a specific crash pulse and not the corridors for that
test, the agency expects to include such corridors in the final rule.
3. Request for Additional Information
In order to help it reach a final decision, the agency is
requesting additional information in several areas.
First, the agency is requesting additional information and data to
help it refine its estimates of the potential benefits and net effects
on safety that would be likely to result from depowering. As discussed
above, the estimates presented in the PRE and summarized above are
necessarily based on very limited data. The agency requests commenters
to address the analyses presented in the PRE, including what
conclusions should be drawn from the various test data, modeling data,
Holden study, and other information presented in that evaluation,
concerning the effect of depowering on fatalities and injuries. The
agency also requests commenters to provide additional relevant
information, including test data, real world studies, and engineering
analyses.
Second, the agency recognizes that there are significant
uncertainties associated with the analyses of the available data and
the resulting estimates of benefits and disbenefits. If, contrary to
the agency's expectation and best judgment, this rulemaking were to
[[Page 823]]
result in a large net loss of life, would taking action (through the
adoption of the proposed amendment) to save the children and short
adult drivers being fatally injured by air bags still be the correct
policy choice?
Third, the agency is seeking comment on the sled pulse test
recently recommended by AAMA. The agency has written to AAMA requesting
information on why AAMA selected the particular recommended pulse, the
amount of depowering that would be permitted for various vehicle types,
how those changes would translate into 30 mph barrier test results, and
specific manufacturer plans (on a model-by-model basis, if possible)
concerning the amount of depowering that would occur if that
alternative is adopted in the final rule. This information will be
docketed as soon as possible after it is received by the agency. The
agency also requests specific estimates on the overall impacts on
safety, for children, belted and unbelted passengers, and belted and
unbelted drivers.
Fourth, NHTSA requests specific analysis comparing the potential
benefits and net effects on safety of the two proposed alternatives.
The agency notes that, in a November 13, 1996 submission, AAMA provided
estimates concerning its members' ability to depower air bags under
various alternative amendments to Standard No. 208. AAMA stated that,
for purposes of its analysis, depowering was defined as reducing the
force produced by air bags to a level which is estimated to reduce the
risk of air bag related fatalities to a 5th percentile unbelted female
and unbelted child as close to zero as possible, while still meeting
all belted occupant injury criteria. According to AAMA, this generally
corresponds to a 25 to 35 percent average reduction in total inflator
output and peak mass flow. AAMA provided the following chart:
AAMA Estimates for Air Bag Depowering
The percentage of air bag systems that could be depowered noted
below is based on engineering judgment of AAMA members relative to the
ability to depower the current air bag design to a level needed to
provide meaningful benefit.
Regulatory Action #1--Raise Chest Criterion to 80 g's
passenger cars--36%
trucks--27%
total--31%
Leadtime to implement--6 to 9 months to 4 years
Regulatory Action #2--80 g's + delete angle barrier
passenger cars--43%
trucks--41%
total--42%
Leadtime to implement--6 to 9 months to 3 years
Regulatory Action #3--80 g's + delete angle barrier + 15 msec HIC
passenger cars--48%
trucks--57%
total--53%
Leadtime to implement--6 to 9 months to 3 years
Regulatory Action #4--125 msec Generic Sled Test
100% of total fleet--leadtime to implement--6 to 9 months, complete
within 2 years.
Based on compliance data and its limited testing of depowered air
bags, the agency believes that an 80 g requirement would permit
manufacturers to depower essentially all of their vehicles by 20 to 35
percent, while AAMA estimates that only 31 percent of vehicles could be
depowered ``to a level needed to provide meaningful benefit.''
One reason for the difference in the assessment of the sufficiency
of the 80 g requirement is that the manufacturers contemplate
depowering more than 20-35 percent in the case of the more aggressive
air bags. As discussed earlier in this notice, the agency's testing
indicates that a considerably higher level of depowering might be
needed for some vehicles to significantly reduce the chance of fatality
to out-of-position children.
NHTSA has not conducted angle tests with depowered air bags, so
another reason for the difference might be that Standard No. 208's
current angle test requirement could be a limiting factor even with an
80 g requirement.
The agency requests the individual manufacturers to provide
specific analysis, on a model-by-model basis, if possible, comparing
the amount of depowering that would be permitted by an increase in the
chest acceleration limit alone to that which would be permitted by the
AAMA generic sled pulse test, and describing the reasons for any
differences in these two levels of depowering. NHTSA has already
requested this information from AAMA and will docket it as soon as
possible after it is received by the agency.
Fifth, NHTSA is requesting additional information concerning the
extent of the existing problem of driver fatalities and injuries from
air bags, and the amount of depowering that would be needed for various
vehicle types to address those fatalities and injuries. As discussed
earlier in this notice, there are substantial differences between the
passenger and driver air bag problems. While the annual number of child
fatalities is very small but growing steadily, the annual number of
adult fatalities does not appear to be growing. While the agency is
aware of 18 children who have been fatally injured by air bags this
year, it is aware of only one driver who has been fatally injured by an
air bag in the United States during the same period. This apparent
nearly total absence of driver fatalities has occurred despite the
greater than two-to-one ratio of vehicles with driver air bags to
vehicles with passenger air bags and the four-to-one ratio of drivers
to front seat passengers. (As noted above, however, the agency's
figures for driver fatalities are not the result of a census.)
Moreover, while most child fatalities have occurred in very recent
model year vehicles, the agency is aware of only one woman 5 feet 2
inches or less who has died in a post model year 1992 vehicle. Finally,
the ratio of lives saved by air bags to persons fatally injured is very
different for driver air bags than passenger air bags. Driver air bags
are estimated to have saved 1500 lives, as compared to 19 persons
fatally injured. Passenger air bags are estimated to have saved 164
lives, as compared to 32 persons fatally injured.
There are also considerable differences between the size and basic
designs of driver and passenger air bags, and the mechanisms by which
drivers and children are likely to become too close to the air bag. As
discussed earlier in this notice, unrestrained or improperly restrained
children are likely to be propelled up against the air bag before
deployment as a result of pre-crash braking, and children in rear-
facing infant restraints are positioned with their heads up against the
air bags. Since drivers have their feet on the brake and/or accelerator
pedals and/or floor and are holding the steering wheel, they are not
likely to be propelled forward as a result of pre-crash braking to the
extent that children are. Pre-braking and crash forces will, however,
cause drivers to move toward the air bag. Drivers who sit very close to
the steering wheel are at greater risk of being too close to the air
bag at the time of deployment, especially if they are unrestrained.
Because driver air bags have been produced in large numbers for
several years longer than passenger air bags, the vehicle manufacturers
have had time in a number of instances to redesign driver air bags to
incorporate a number of
[[Page 824]]
countermeasures that reduce the risk to out-of-position occupants. In
deciding whether to adopt its proposal to reduce the stringency of
Standard No. 208 as it applies to driver air bags, the agency will
therefore take care that it is assessing both current and expected air
bag designs.
By way of illustration, General Motors commented in December 1995
that it has introduced a number of air bag system features that
according to its test results should reduce the risk of inflation
induced injury. These features include minimized inflator output and
bag size, module cover tear seam geometry, low break-out force module
cover, bag fold, and recessed air bag module. General Motors also
stated that it was in the process of introducing air bag systems that
include a number of features that can help to further reduce the
inflation-induced loads to which an occupant can be subjected. These
features (which repeat some of the earlier ones listed by that company)
include recessed air bag modules, new bag folds, improved air bag
module tear seam geometries, low break-out force air bag module covers,
minimized bag volumes, low output inflators, and air bag venting
technologies.
NHTSA is also aware that other companies have also redesigned
driver air bags in ways that should reduce air bag aggressivity. Agency
testing of several new designs shows a substantial reduction in the
risk to out-of-position occupants, especially with respect to chest
injury, measured as V*C. However, the agency also tested some driver
air bags that showed a substantial reduction in some injury reference
values and increases in others.
NHTSA requests information on the potential which current driver
air bags have for creating adverse side effects. Among other things,
the agency requests vehicle manufacturers to provide detailed
information, on a model-by-model basis, if possible, concerning all
relevant design changes they have made, or expect to make, in their
vehicles that may have reduced, or will reduce, the risk of injury or
fatality to drivers from air bags. This would include changes in air
bag designs, including deployment threshold changes, and changes in
related vehicle components. This information will help the agency
assess the potential of adverse side effects associated with model year
1997 vehicles, as opposed to the potential associated with model year
1990-92 vehicles.
The agency also requests information on the number of driver air
bag fatalities that have occurred to date. NHTSA does not have as much
information on driver fatalities as child fatalities, because it does
not have the resources to investigate every adult fatality that occurs
in a vehicle with an air bag. Therefore, there may be driver fatalities
that the agency is not aware of. NHTSA is especially interested in
knowing about fatalities that have occurred over the past three years,
especially involving late-model vehicles.
NHTSA also requests comments on the extent to which depowering of
current air bags would address driver air bag fatalities, and on the
extent of the associated safety tradeoffs. Finally, the agency requests
comments and data concerning the extent of the need to change Standard
No. 208 to permit various levels of depowering, and on the alternatives
of raising the standard's chest g limit and/or adopting the AAMA
recommended generic sled pulse test.
In view of the potentially substantial disbenefits associated with
depowering driver air bags, the agency requests comment about the
advisability of limiting the proposed amendment to passenger air bags
only. The agency requests specific information about the cost and
leadtime implications of excluding driver air bags from the amendment
as well as the effects it would have on reducing the magnitude of the
apparent disbenefits associated with depowering driver air bags. In
making that request, NHTSA recognizes that considerable depowering of
driver air bags is already possible under the current standard.
D. Consideration of Other Alternatives
In developing this proposal, NHTSA considered an array of
regulatory and nonregulatory (e.g., education) approaches that would
address the air bag safety problem.
Other regulatory approaches to facilitate depowering that have been
advocated by the industry include dropping the unbelted test
altogether, or requiring that the unbelted requirements be met at
speeds up to 25 mph instead of 30 mph.
NHTSA is not proposing to drop the unbelted test altogether. A
number of vehicle manufacturers have argued that the inclusion of
unbelted test requirements in Standard No. 208 should be reconsidered
in light of the fact that belt use has increased from 14 percent in
1983 to around 68 percent today. The agency recognizes that, at some
point, belt use might rise to a point at which retention of the
unbelted test requirements might no longer be appropriate. The agency
notes that belt use in Australia is over 95 percent, and averages 93
percent in Canada. However, as noted above, the belt use among fatally
injured vehicle occupants is less than 40 percent. Since smart air bags
may soon be available that adjust air bag deployment levels based on
belt use or nonuse, the possible need to amend the unbelted test
requirements may be relatively short-lived. NHTSA will consider the
issue of the unbelted test requirements in the context of its
forthcoming rulemaking on smart air bags. If it appears that such smart
air bags will not be available in the near term, the agency will also
consider whether there might be a percentage of belt use at which the
agency should examine changing the unbelted test requirements and
whether any legislative amendments might be necessary for that purpose.
The agency is also not proposing to reduce the unbelted test speed
to 25 mph. While this approach was advocated in the past by Ford, Ford
has now reached consensus with the other members of AAMA on the
approach of replacing the unbelted crash test requirement with a sled
test protocol incorporating a standardized crash pulse. In addition,
the agency believes that the proposed approaches are preferable to
reducing the test speed because they would allow a more rapid
introduction of depowered air bags.
Given the possibility that amending Standard No. 208 to permit
significant depowering might lead to a reduction in the lives saved by
air bags, NHTSA has assessed other available approaches to the air bag
safety problem in terms of their relative timeliness, effectiveness and
net effect on safety. The results of such a comparative assessment are
relevant to deciding whether there is a need to reduce stringency of
the standard and, if so, for how long. The agency has considered the
following alternatives in addition to depowering. (There is some
overlap between the alternatives; for example, smart air bags may
incorporate some design features that could also be used individually.)
Behavior-Related Actions Only. One possibility would be for NHTSA
to focus entirely on behavior-related actions, such as public
information efforts, encouraging the States to improve and enforce
their safety belt and child restraint use laws, requiring improved
warning labels, and permitting or requiring passenger manual cut-off
switches (a technological change which would also require behavioral
changes to be effective) in all vehicles. Behavioral changes are
especially relevant to the problem of child fatalities caused by air
bags, since these fatalities can be prevented by behavioral means,
e.g., ensuring that
[[Page 825]]
children always buckle up and that they sit in the back seat whenever
possible.
NHTSA is actively pursuing efforts to bring about behavioral
changes. The agency's efforts include its public education campaigns,
addressed at length in the August 1996 NPRM and other Federal Register
notices, and the agency's final rule (issued November 22, 1996)
amending Standards No. 208 and No. 213 to require improved labeling to
provide better assurance that drivers and other occupants are aware of
the dangers posed by air bags to children.
As discussed above, NHTSA is a part of a coalition including
automobile manufacturers, air bag suppliers, insurance companies and
safety organizations working to improve safety belt use by a variety of
means, including education efforts, urging the States to adopt primary
enforcement safety belt use laws, and improving enforcement of seat
belt and child seat use laws. To the extent that these efforts are
successful, belt use rates should increase.
The agency's rulemaking concerning manual cutoff switches for
passenger air bags also represents a way of reducing air bag fatalities
by behavioral means. The switches provide drivers, in vehicles lacking
a back seat large enough to accommodate a rear-facing infant seat, with
a means of ensuring that their young children, particularly infants,
would not be harmed by the air bag.
However, while behavioral changes are an important part of the
efforts to reduce low speed fatalities due to air bags, it is not
realistic to expect that those efforts will fully solve the problem.
This is illustrated by the number of drivers who continue to drive
without safety belts and the number of children who remain
unrestrained, despite decades of efforts to encourage people to wear
safety belts and use child restraints, and the existence of laws
requiring such use in most states. Accordingly, it is also necessary
for the agency to pursue technological changes.
Higher Deployment Thresholds--i.e., Increasing the Vehicle Speed at
Which Air Bags Deploy. NHTSA has also considered whether vehicle
manufacturers should be required to increase the minimum vehicle speed
at which air bags deploy, and possibly have different deployment
thresholds for the unbelted and belted conditions, as a short-term
solution for reducing air-bag-induced fatalities and injuries. This
would lessen the number of deployments at low speed where the
possibility of serious injury for occupants (even unrestrained
occupants) is small.26
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\26\ As part of a comprehensive rulemaking on automatic
restraints (then called ``passive restraints''), in 1970 NHTSA
proposed to require that air bags not deploy when the vehicle
impacts a fixed barrier at any velocity less than 15 miles per hour,
at any angle. 35 Fed. Reg. 16937, at 16938; November 3, 1970.
However, after considering opposing comments from vehicle
manufacturers, the agency did not adopt this requirement because it
determined that it was preferable to allow manufacturers freedom in
the design of their protective systems at all speeds. 36 Fed. Reg.
4600, at 4602; March 10, 1971.
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As indicated above, CFAS and Public Citizen requested in their
petition that, for vehicles without dual stage inflators, a minimum
``trigger speed'' of 10 mph barrier equivalent velocity (BEV) be set
beginning with the 1998 model year for passenger cars and 1999 for
light trucks. The CFAS petition submitted a few days earlier had
suggested a 12 mph minimum deployment threshold. Mercedes Benz
suggested in its comment on the August 1996 NPRM the possibility of
using thresholds as high as 18 mph regardless of belt use, as a short-
term means of addressing the problem of low speed fatalities to
children.27 NTSB recommended that the agency evaluate the effect
of higher deployment thresholds for passenger air bags in combination
with certain recommended changes in air bag performance certification
testing, and then modify the deployment thresholds based on the
findings of the evaluation. The Holden air bag, in addition to being
designed to deploy less aggressively, has significantly higher
thresholds than typical U.S. air bags. As noted above, Holden bags have
a ``no-fire'' threshold of 12.4 mph and an ``always-fire'' threshold of
17.4 mph. While thresholds vary for U.S. air bags, a representative one
has a ``no-fire'' threshold of 9 mph and an ``always-fire'' threshold
of 14 mph.28
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\27\ That company currently uses a threshold of 12 mph for
unbelted occupants and 18 mph for belted occupants. If no occupant
is present, the air bag does not deploy, regardless of the speed.
\28\ The agency notes that regardless of what nominal design
threshold is selected by a manufacturer, some deployments will occur
at speeds below that nominal value, and some air bags will not
deploy at speeds slightly above that value. The range of delta V's
at which a particular air bag may either deploy or not deploy is
dependent on a number of factors, including manufacturer efforts to
fine-tune the deployment decision to reflect different crash
conditions with the same delta V, and variability inherent in air
bag designs.
---------------------------------------------------------------------------
NHTSA stated in its August 1996 NPRM that it is interested in
whether increasing the minimum vehicle speed at which an air bag
deploys, and possibly having different deployment thresholds for the
unbelted and belted conditions, may be an effective way to reduce air
bag-induced injuries. An examination of the child fatalities that have
occurred to date shows why such an increase might be effective.
Of the 32 crashes in which deployment of the passenger air bag
caused a child fatality, NHTSA has, to date, analyzed the severity of
24 of those crashes. The estimated change in velocity (delta V) was 20
mph or less in 23 cases, 15 mph or less in 20 cases, and 10 mph or less
in eight cases. For the remaining case in the group of 23, delta V was
estimated at 20-25 mph. For an additional four cases, the agency did
not estimate crash severity but did a damage estimate. Damage severity
was low in three cases and moderate in the fourth. The remaining four
cases out of the 32 crashes are still under investigation. These data
suggest that a moderate increase in threshold could make a significant
contribution to reducing child fatalities due to air bags.
NHTSA recognizes that there are many highly complex issues involved
in selecting thresholds, including leadtime issues and safety
tradeoffs. The agency recognizes that the use of a higher threshold, in
combination with the mechanical crash severity sensors used by some
vehicle manufacturers, could delay the signal to inflate and thus
provide less time for the air bag to deploy, and possibly necessitate
even more aggressive air bag deployments. NHTSA believes this problem
could be addressed by adding an additional mechanical sensor, but that
would involve a hardware change and require additional leadtime. The
agency believes that the leadtime to achieve universal usage of
electronic sensors would be at least two years. For vehicles which
already have electronic sensors, there would be a shorter leadtime for
increasing thresholds.
Additional tradeoffs involve the possibility of increased non-fatal
injuries. Auto manufacturers have stated that selection of thresholds
is typically based on their analysis of the crash severity at which
serious facial, head, and brain injuries may occur. However, the agency
believes that current steering assembly designs might permit thresholds
to be increased without affecting the risk of facial fractures.
NHTSA believes that manufacturers could significantly increase
deployment thresholds and still comply with the current requirements of
Standard No. 208, although the agency does not have specific
information concerning how high. Standard No. 208 does not specify a
threshold requirement but does require vehicles to pass crash test
requirements at speeds up to 30 mph. The agency believes that most, and
perhaps all current vehicles could
[[Page 826]]
probably pass the unbelted crash test requirements without air bags at
speeds as high as 16 mph. Therefore, for manufacturers with the
capability of increasing thresholds quickly, the necessity of meeting
the injury criteria at speeds below the higher thresholds does not
appear to be an impediment. The agency requests comments on whether
this belief is correct.
NHTSA notes that mandating a minimum deployment threshold would be
design-restrictive and could undermine the development of two-stage
systems that could deploy ``softer'' air bags at lower speeds.
The agency requests commenters to provide analysis comparing the
benefits/disbenefits and leadtime for increasing deployment thresholds
versus depowering.
Dual Stage Inflators. Public Citizen and CFAS petitioned for the
agency to amend Standard No. 208 to require dual stage inflation air
bags beginning with the 1999 model year. The petitioners stated that
dual inflation bags offer the best solution in the near future, as they
neither surrender protection for adults in high-speed crashes, nor
sacrifice low-speed crash protection for children. The petitioners
asserted that inflator deployment and trigger speeds can be adjusted
now without waiting until the 21st century for smart air bags that use
infrared or sonic sensors to determine whether there is an out-of-
position occupant.
NHTSA notes that the leadtime for implementing dual stage inflators
is longer than for depowering. As indicated above, manufacturers can
begin introducing depowered air bags in six to nine months and
potentially complete their introduction of depowered air bags by a year
later. Based on comments from suppliers, the earliest that dual stage
inflators could begin to be implemented is for model year 1999, i.e.,
September 1998.
While the leadtime is longer, it appears that dual stage inflators
could provide essentially all of the benefits associated with
depowering, without raising the same possibility of safety tradeoffs.
This is because such designs would in essence provide a ``depowered''
air bag for low to moderate speed crashes (and possibly all belted
crashes), and a fully powered air bag to provide protection to unbelted
occupants in higher speed crashes. The agency notes that dual stage
inflators might qualify as smart air bags.
Other Air Bag-Related Changes, Not Including Smart Bags. In its
November 1995 request for comments, the agency requested comments on
many variables in air bag design and related vehicle design that can
affect aggressivity. Variables related to air bag design include air
bag volume, fold patterns, tethering, venting, mass/material, shape and
size of air bag module opening, and module location and deployment
path. Related vehicle design variables include such things as recessing
the inflator/air bag in the steering wheel assembly or in the dash,
pedal adjusters, and safety belt pretensioners. The agency notes that
Holden safety belt systems use webbing clamps, which help reduce the
payout and spooling of the webbing. In its August 2, 1996 comment, CFAS
cited many of these variables (as well as ones discussed above in
connection with its petitions) in arguing that other means of reducing
air bag aggressivity should be used before manufacturers resort to
decreasing the inflation rates.
NHTSA agrees that there are many variables besides inflator power
which affect air bag aggressivity, including many cited by CFAS. Many
of these changes already are being made. However, any currently
unplanned changes relating to these other variables would generally
require unanticipated hardware changes, which would take longer to
implement than depowering. The agency believes that hardware changes
require leadtimes of at least two years. In addition, the agency does
not have information showing that these types of changes would be as
effective as depowering in addressing child fatalities.
Smart Air Bags. NHTSA has similarly considered how quickly
manufacturers could begin installation of smart air bags. As discussed
above, the vehicle manufacturers have indicated that they plan to
introduce these devices as soon as they become available. Several
suppliers commenting on the August 1996 NPRM indicated that smart air
bags can begin to be phased in beginning with the model year 1999
fleet, i.e., approximately September 1, 1998.
Tentative Conclusions about Alternatives. As the agency considers
technological alternatives to address the adverse side effects of air
bags, several things seem evident. First, for many vehicles, depowering
has a shorter leadtime than any of the other alternatives. While
manufacturers can begin introducing depowered air bag vehicles in six
to nine months and potentially complete the depowering of the air bags
in their vehicles within about a year after they begin introduction,
dual level inflators and other smart air bags cannot begin to be phased
in until at least September 1, 1998. The agency has less information on
the leadtime for raising deployment thresholds, but it appears that it
would take at least two years to switch from mechanical to electronic
sensors.
Second, there are various alternatives that may be superior to
depowering, i.e., alternatives that result in equal or greater benefits
without raising the possibility of adverse safety tradeoffs, but whose
leadtime is longer than that of depowering. Therefore, while depowering
appears to be an appropriate short-term approach, there is no need for
permanently changing the Standard to enable manufacturers to fully
address the adverse side effects of air bags.
NHTSA also believes it is important to emphasize that a change in
Standard No. 208 is not required to permit manufacturers to implement
these other alternatives. \29\ The agency expects to ultimately require
smart air bags through rulemaking. In the meantime, the agency is not
endorsing depowering over other solutions. Instead, the agency is
proposing a regulatory change to add depowering to the alternatives
available to the vehicle manufacturers to address this problem on a
short-term basis. To the extent that manufacturers can implement
superior alternatives for some vehicles, the agency would encourage
them to do so.
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\29\ All of these various other alternatives, i.e., dual level
inflators, smart air bags, higher deployment thresholds, and the
replacement of mechanical sensors by electronic ones, are permitted
by the existing provisions of Standard No. 208. The Standard already
provides considerable design flexibility for manufacturers. The
Standard's automatic protection requirements are performance
requirements and do not specify the design of an air bag. Instead,
vehicles must meet specified injury criteria, including criteria for
the head and chest, measured on properly positioned test dummies,
during a barrier crash test, at speeds up to 30 mph.
While the Standard requires air bags to provide protection for
properly positioned occupants (belted and unbelted) in relatively
severe crashes, and very fast air bags may be necessary to provide
such protection, the standard does not require the same speed of
deployment in the presence of out-of- position occupants, or even
any deployment at all. Instead, the standard makes possible the use
of dual or multiple level inflator systems and automatic cut-off
devices for out-of-position occupants and rear-facing infant
restraints. Concepts such as dual level inflator systems and devices
that sense occupant position and measure occupant size or weight are
not new, and were cited by the agency in its 1984 rulemaking. NHTSA
also notes that Standard No. 208 does not specify a vehicle speed at
which air bags must deploy, and that thresholds could be raised
substantially for most current vehicles without creating a Standard
No. 208 compliance problem. Therefore, regulatory changes are not
needed to permit manufacturers to implement these solutions.
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Some commenters, including Takata, expressed concern that a
reduction in Standard No. 208's performance requirements may delay the
introduction of superior alternatives. NHTSA does not believe a short-
term
[[Page 827]]
temporary amendment would result in such a delay. Instead, such an
amendment would provide maximum flexibility to the vehicle
manufacturers to address the problem, while they work on better
solutions. Moreover, the agency's forthcoming proposal for smart air
bags will seek to ensure that air bags reach their full fatality and
injury reducing potential.
NHTSA recognizes, however, that its proposal to permit or
facilitate depowering of air bags is on a faster track than the
rulemaking to require smart air bags. Under the agency's rulemaking
schedule, it plans to issue a final rule concerning depowering before a
final rule to require smart air bags. Given that NHTSA contemplates
permitting depowering until smart bags are introduced, the question
arises of how the agency should limit the duration of the temporary
amendment for depowering. One approach would be to specify a several
year duration and revisit the issue in the context of the rulemaking on
smart air bags. NHTSA requests comments on this issue.
The agency notes that Public Citizen and CFAS requested that the
agency require dual stage inflators quickly rather than wait for more
advanced smart air bags. The agency believes there is a consensus that
smart air bags are needed to fully address the problem of child
fatalities. The ``first'' stage of a dual stage inflator would be
similar to depowered air bags in reducing but not eliminating the
possibility of serious injury or fatality to an out-of-position child.
In its August 1996 proposal, NHTSA noted that if it does decide to
require smart passenger air bags, its leadtime decision would have to
take into consideration the differing leadtimes for the various kinds
of smart bags under development, and the fact that the longest
leadtimes will be those for the more advanced smart bags potentially
offering the greatest net benefits. The agency also noted that, as a
practical matter, the longer the time needed to develop and implement
the most advanced smart bags, the greater the need would be to
implement interim designs that would protect children automatically.
These same types of considerations are relevant to the Public
Citizen/CFAS request. If the ultimate result is for the vehicle
manufacturers to add smart air bags to their fleets, the agency
believes that the quickest and most efficient way of accomplishing this
task would be to go directly to smart air bags, which may include dual
stage inflators.
NHTSA requests commenters to address how the agency should consider
this factor in reaching a final decision on this proposal. The agency
also requests the vehicle manufacturers to provide their latest
timetables for implementing measures that will enable them not only to
solve the problem of the adverse side effects of air bags, but also to
meet the current unbelted requirements of Standard No. 208, i.e., 60 g
chest acceleration, 1000 HIC, etc.
With respect to Advocates' recommendation that the agency not
predicate major regulatory changes on anything less than clear and
convincing evidence that a modification will improve safety, NHTSA
agrees that caution should be exercised in making a regulatory change.
This is why the agency initiated its test program to evaluate various
issues related to addressing the problem of low speed air bag
fatalities and injuries, including the potential safety benefits and
trade-offs associated with depowering air bags. NHTSA also believes,
however, that it has a duty to act to address this problem, and promote
the long term interests of safety, even in the presence of the
possibility of short-term tradeoffs and inevitable remaining
uncertainties about the various approaches and alternatives.
E. Effective Date and Comment Period
The proposed amendment might be major and thus subject to
Congressional review under the provisions in Title 5 of the United
States Code concerning Congressional review of agency rulemaking. If
the amendment is major, the agency requests comments on whether the
amendment should be make effective immediately upon publication because
it addresses an urgent safety problem, most particularly the death of
young children. The proposed amendment would permit or facilitate the
immediate depowering of air bags, thereby helping to reduce child
fatalities from air bags. The proposed amendment would not impose any
new requirements, but instead would provide additional flexibility to
manufacturers in addressing this problem.
Given the importance of enabling manufacturers to address this
urgent safety problem quickly, NHTSA is providing a shortened comment
period of 30 days.
F. Relationship to Other Actions
NHTSA invites commenters to address whether and how any of the
other actions being taken by the agency to address adverse effects of
air bags should affect its decision concerning this proposal.
VI. Response to AAMA and CFAS Petitions
This notice constitutes a granting of AAMA's petition for
rulemaking. The agency is proposing the AAMA sled test as one of the
alternative amendments in thi
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