CHAPTER II. SAFETY PROBLEM


    This section estimates the number of child passenger vehicle fatalities and injuries in frontal crashes that could benefit from adapting FMVSS 208 injury criteria. A child is defined as between ages 0 to 12 years old. All the statistics presented here are for children 0 to 12 years old to demonstrate the child injury safety problem (1). However, only children sitting in child restraints are assumed to be impacted by FVMSS 213 and are used in the benefit estimation.

    The real-world crash data used to derive the fatalities and non-fatal injuries in frontal crashes are from the following files: the 1999 Fatality Analysis Reporting System (FARS), the 1999 General Estimates System (GES) (2), and the 1993-2000 Crashworthiness Data System (CDS). Both GES and CDS are sampling systems. CDS has a much smaller sample than does GES, but with a more in-depth investigation of injury profiles. Thus, the multiple years of CDS were used in the detail descriptive statistics analysis to reduce variability.

    The fatal frontal crashes in FARS were defined as the initial (IMPACT1) or principal (IMPACT2) impact points in the 11, 12, and 1 o'clock directions. Because data elements describing crash characteristics varied between FARS and CDS, frontal crashes were defined differently in CDS. The frontal crashes in CDS were defined by their principal direction of force (DOF1), the general area of damage (GAD1), and the primary specific horizontal location (SHL1). They included crashes with (1) DOF1 between 11 and 1 o'clock direction, or (2) DOF1 was 10 or 2 o'clock direction and GAD1 was front or side with damage forward of the A-pillar.

    The overall fatal problem size was derived from 1999 FARS level. The non-fatal injuries in frontal crashes were derived from 1993-2000 CDS. CDS contains data on all passenger vehicle crashes where at least one passenger vehicle was towed, while GES is a sample of all police-reported crashes not limited to passenger vehicle towaway crashes. GES is a better source to provide national statistics on nonfatal crashes in U.S. Therefore, the injury numbers then were adjusted to 1999 GES CDS-equivalent levels. The crash severity and injured body region percentage distribution are based on 1993-2000 CDS. Similarly, the corresponding fatalities and injuries were adjusted to the 1999 FARS and 1999 GES CDS-equivalent level, respectively.

    GES does not include clock impact direction as does FARS and CDS, thus the analysis does not use frontal crashes in GES for injury adjustment. Instead, all the injuries in the GES CDS-equivalent crashes, regardless of crash types, were used in the injury adjustment process. The injury adjustment factor, for each pre-specific age group, from CDS to the GES CDS-equivalent level is the ratio between the passenger vehicle occupants in GES CDS-equivalent crashes and in CDS crashes, i.e.,

    The injury adjustment factor formula


    A. Problem Size

    Annually, about 573 child passenger vehicle occupants age 0 to 12 years old are fatally injured in the front or rear seats in frontal crashes. In 1999, 100 of these fatally injured children were in a child restraint system (CRS). Eighty-two (14 percent) of these fatalities were in a properly used CRS when this crash occurred: 16 were in the front seats and 66 were in the rear seats. Eighteen were in an improperly used CRS. Table II-1 summarizes the child occupant fatalities in frontal crashes by age groups, restraint use, and seating position. Note that the restraint use was based on the 1999 FARS. The rear seats include the second, third, and fourth row seats.

    In addition to fatalities, frontal crashes are also associated with 8,916 MAIS (3) 2-5 and 95,517 MAIS 1 non-fatal injuries, annually. Tables II-2 and II-3 report these child MAIS 2-5 and MAIS 1injuries, respectively, by age groups, restraint use, and seating position. As shown in these two tables, about 1,800 (20 percent) MAIS 2-5 and 19,289 (20 percent) MAIS 1 injuries were in a properly used CRS when the frontal crash occurred. The injuries were derived from 1993-2000 CDS and then adjusted to the 1999 GES CDS-equivalent level. The adjustment is achieved by multiplying the adjustment factor as described previously to the annualized injuries from 1993-2000 CDS. CDS did not record whether the child safety was used properly no not as did in FARS. The improperly used CRS in CDS was defined as that the child safety seat orientation was used not according to the manufacturer's designed orientation use.


Table II-1 Child Occupant Fatalities in Frontal Crashes
By Seating Position, Age, and Restraint Use

Age
(Years Old)
Child
Restraint
System*
Improperly
Used CRS
Belted Not
Belted
Total
Front Seats
0-1 15 3 3 28 49
2-3 1 1 8 29 39
4-6 0 0 19 36 55
7-10 0 0 31 40 71
11-12 0 0 11 27 38
Total 16 4 72 160 252
Rear Seats
0-1 31 9 5 18 63
2-3 28 4 4 28 64
4-6 6 1 32 34 73
7-10 1 0 33 60 94
11-12 0 0 11 16 27
Total 66 14 85 156 321
Front + Rear Seats
0-1 46 12 8 46 112
2-3 29 5 12 57 103
4-6 6 1 51 70 128
7-10 1 0 64 100 165
11-12 0 0 22 43 65
Total 82 18 157 316 573


Table II-2 Child Occupant Non-Fatal MAIS 2-5 Non-Fatal Injuries in
Frontal Crashes By Seating Position, Age, and Restraint Use

Age
(Years Old)
Child
Restraint
System*
Improperly
Used CRS
Belted Not
Belted
Total
Front Seats
0-1 419 0 142 151 712
2-3 30 0 308 96 434
4-6 35 0 200 942 1177
7-10 0 0 787 291 1078
11-12 0 0 208 225 433
Total 484 0 1645 1705 3834
Rear Seats
0-1 479 10 92 124 705
2-3 791 8 40 172 1011
4-6 46 0 528 337 911
7-10 0 0 882 848 1730
11-12 0 0 631 94 725
Total 1316 18 2173 1575 5082
Front + Rear Seats
0-1 898 10 234 275 1417
2-3 821 8 348 268 1445
4-6 81 0 728 1279 2088
7-10 0 0 1669 1139 2808
11-12 0 0 839 319 1158
Total 1800 18 3818 3280 8916


Table II-3 Child Occupant Non-Fatal MAIS 1 Injuries in Frontal Crashes
By Seating Position, Age, and Restraint Use

Age
(Years Old)
Child
Restraint
System*
Improperly
Used CRS
Belted Not
Belted
Total
Front Seats
0-1 1456 237 781 782 3256
2-3 2607 109 1270 395 4381
4-6 186 0 7706 1392 9284
7-10 0 0 9467 3867 13334
11-12 0 0 4928 2894 7822
Total 4249 346 24152 9330 38077
Rear Seats
0-1 4946 4753 231 1616 11546
2-3 7620 317 1716 1072 10725
4-6 2474 0 5234 1808 9516
7-10 0 0 14279 3796 18075
11-12 0 0 3713 3865 7578
Total 15040 5070 25173 12157 57440
Front + Rear Seats
0-1 6402 4990 1012 2398 14802
2-3 10227 426 2986 1467 15106
4-6 2660 0 12940 3200 18800
7-10 0 0 23746 7663 31409
11-12 0 0 8641 6759 15400
Total 19289 5416 49325 21487 95517


    B. Children in CRS

    Of particular interest for the analysis are the children in a CRS when the crash occurred. Table II-4 shows the children in a CRS by seating position and orientation of the CRS. Of all the 16 child occupant fatalities in the front seat, 9 were in a forward-facing CRS and 7 were in a rear-facing CRS. Of the 66 rear-outboard child occupant fatalities, 52 were in a forward-facing CRS and 14 were in a rear-facing CRS. As expected, all the fatalities and injuries for children age 2 and older sitting in the rear seat were in a forward-facing CRS.

    As for MAIS 2-5 injuries, about 322 front seating children were in a forward-facing CRS and 162 were in a rear-facing CRS. Of the 1,316 rear seating MAIS 2-5 child injuries, 1,102 were in forward-facing CRS and 214 were in the rear-facing CRS.


Table II-4 Children in Properly Used Child Restraint System (CRS)
by Age, Seating Position, and Orientation of the CRS

Age
(Years Old)
Front Seats Rear Seats
Forward
Facing
Rear
Facing
Total Forward
Facing
Rear
Facing
Total
Fatalities
0-1 9 6 15 17 14 31
2-3 0 1 1 28 0 28
4-6 0 0 0 6 0 6
7-10 0 0 0 1 0 1
11-12 0 0 0 0 0 0
Total 9 7 16 52 14 66
MAIS 2-5 Injuries
0-1 257 162 419 265 214 479
2-3 30 0 30 791 0 791
4-6 35 0 35 46 0 46
7-10 0 0 0 0 0 0
11-12 0 0 0 0 0 0
Total 322 162 484 1102 214 1316
MAIS 1 Injuries
0-1 1342 114 1456 3386 1560 4946
2-3 2607 0 2607 7620 0 7620
4-6 186 0 186 2474 0 2474
7-10 0 0 0 0 0 0
11-12 0 0 0 0 0 0
Total 4135 114 4249 13480 1560 15040


    C. Relevant Statistics

    The section presents statistics by crash severity (measured by Delta-V) and injured body region. The majority of the MAIS 1 injuries were skin bruises. We believe the effectiveness of the new proposal for these injuries would be minimal. Thus, the analysis focuses on fatalities and MAIS 2-5 non-fatal injuries. Due to small sample sizes, the statistics are for all children regardless of age, seating position, and restraint use.

    Statistics by Crash Severity

    As shown in Table II-5, about 60 percent of child fatalities and 90 percent of MAIS 2-5 injuries in frontal crashes occurred at impact speeds less than or equal to 30 mph. Note that the percentage distribution in Table II-5 was based on the 1993-2000 CDS. CDS is the only crash database that contains the Delta-V information.


Table II-5 All Child MAIS 2+ Occupant Injuries by Crash Severity
Regardless of Restraint Use

Injury Severity
Frequency Percent
Crash Severity (Delta-V in MPH)
0-20 21-30 31-40 41+ Total
Fatality 162
28%
173
32%
119
21%
119
21%
573
100%
MAIS 2-5 Injuries 5260
59%
2764
31%
713
8%
179
2%
8916
100%


    Statistics by Injured Body Region

    Table II-6 shows the child MAIS 2+ passenger vehicle occupant injuries by MAIS injured body region. Head is the predominate injury body region. Neck injuries were rare occurrences. Due to small sample sizes and unknown injured body regions for fatalities, the percentages derived from MAIS 4-5 and fatalities combined were applied to fatalities. The statistics were based on 1993-2000 CDS. CDS is the only data system used in the analysis that records the injured body region.


Table II-6 All Child MAIS 2+ Injuries by MAIS and Body Region
Regardless of Restraint Use

Injury Severity
Frequency Percent
MAIS Injured Body Region
Head Neck Chest Other* Total
Fatality 407
71%
6
1**%
40
7%
120
21%
573
100%
MAIS 2-5 Injuries 3834
43%
18
0**%
535
6%
4529
51%
8916
100%


    Based on Table II-6, head, neck, and chest comprised about 79 percent of fatalities and 49 percent of all MAIS 2+ injuries. Table II-7 shows the properly used child safety seat occupants with a fatal/MAIS 2-5 head, neck, or chest injuries regardless of seating position. These numbers were about 79 and 49 percent of fatalities and MAIS 2-5 injuries, respectively, in Table II-4.


Table II-7 Children in Properly Used Child Restraint Systems (CRS)
With a Fatal or MAIS 2-5 Head, Neck, or Chest Injury

Age (years Old) Forward-Facing CRS Rear-Facing CRS Total
Fatalities
0-1 21 16 37
2-3 22 0 22
4-6 5 0 5
7-10 1 0 1
11-12 0 0 0
Total 49 16 65
MAIS 2-5 Injuries
0-1 256 184 440
2-3 402 0 402
4-6 40 0 40
7-10 0 0 0
11-12 0 0 0
Total 698 184 882



    1 In some cases, the broader range of ages is needed to get a reasonable estimate of injuries by body region.
    2 General Estimates System Coding Manual 1999.
    3 Maximum Abbreviated Injury Scale, 1-Minor Injury, 2-Moderate Injury, 3-Serious Injury, 4-Severe Injury, 5-Critical Injury. Only one injury with the most severity is counted per occupant.