PROPOSED DUMMIES, INJURY CRITERIA, AND OTHER CHANGES
This chapter discusses the proposed changes for FMVSS 213. These changes include: Hybrid III test dummies, injury criteria and its corresponding injury criterion performance limits (ICPLs), seat assembly, and sled crash pulse. In addition, the chapter provides injury probability risk curves that would be used in the benefit estimates.
A. Proposed Dummies
The agency proposes that FMVSS 213 use a 12-month-old CRABI and the more advanced Hybrid III dummies to replace the Hybrid II dummies. The Hybrid III dummies include a 3-year-old and a 6-year-old dummy. To further protect older children weighing between 50 and 80 pounds, the agency also proposes a 65-pound weighted 6-year-old dummy. This section discusses the proposed Hybrid III dummies and the weighted 6-year-old dummy. Readers can consult the following references for more information on dummy research and analysis:
Hybrid III vs Hybrid II
Currently, FMVSS 213 specifies the 9-month, and Hybrid II 3-year and 6-year-old dummies be used in compliance tests. The 9-month old dummy is only used to measure head excursion. The Hybrid II 3- and 6-year-old dummies are instrumented to measure HIC and chest acceleration and are used to measure head excursion and knee excursion. The12-month-old infant (CRABI) and the Hybrid III 3- and 6-year-old child dummies are equipped with greater instrumentation. These dummies contain a more advanced and biofidelic neck design. Readers can consult the NHTSA technical report titled "A Comparative Evaluation of Hybrid II and Hybrid III Child Dummy Families" for a detailed assessment of dummy equivalency research.
Weighted 6-Year-Old Dummy
The weighted 6-year-old dummy is the Hybrid III 6-year-old dummy instrumented with an extra weight to 65 pounds. A 1994 NHTSA study (1) has shown that children do not properly fit into standard vehicle safety belt systems without booster seats until they reach 4 foot nine inch height which correlates an average weight of 80 pounds. To improve the protection of the children weighing between 50 and 80 pounds, the agency is considering a 10-year-old dummy. A Hybrid III 10-year-old dummy that weighs approximately 78 pounds is under development. The weighted 6-year-old dummy is the agency's near-term solution to cover the weight gap until the completion of the 10-year-old dummy. Readers can consult NHTSA's report "Evaluation of the Weighted Hybrid III Six-Year-Old Dummy, June, 2001" for detailed information.
B. Proposed Injury Criteria
The current FMVSS 213 uses head injury criterion (HIC), chest acceleration (chest g), head excursion, and knee excursion to assess the performance of child restraints. HIC unlimited (HICunlimited), an unrestricted time interval measurement, is used to predict head injury. The injury criteria performance limits (ICPL) are: 1000 for HICunlimited, 60 g for chest acceleration, 28 (test child restraint with tether) or 32 (without tether) inches for head excursion, and 36 inches for knee excursion. The ICPLs are the same for all dummy sizes.
The agency is proposing to amend FMVSS 213 to incorporate FMVSS 208 injury criteria except for the neck limits and its ICPLs. FMVSS 208 requires HIC, chest g , chest deflection, and neck criteria (Nij) with peak neck tension and compression limits to minimize the risk from a deploying air bag. The required ICPLs in FMVSS 208 are different depending on the dummy size to ensure a consistent performance requirement and the adequate safety protection to all occupants.
The proposed HIC as in FMVSS 208 is measured at a 15-millisecond time window (HIC15), as opposed to an unlimited HIC measurement in the current FMVSS 213. For adult dummies, there was a high correlation between HIC36 and HIC15 for long duration pulses. A HIC36 1000 is correlated to HIC15 700. HIC15 is more stringent for short duration pulse (< 25 millisecond pulses). The agency is proposing to use a different set of neck axial force and neck moment intercept values from those specified in the FMVSS 208 for the Nij calculation. The Nij intercept values used in the FMVSS 208 are for out-of-position child occupants since the out-of-position tests were only required for child dummies. However, in the FMVSS 213 test environment, the child dummies are considered to be tested in-position. Therefore, the agency is proposing a set of in-position neck intercept values to be used to calculate Nij. In comments to the FMVSS 208, AMA had recommended in-position Nij intercept values for all dummy size. The agency is proposing FMVSS 213 to adapt these recommended in-position critical values. See Table III-1 for these critical neck values. The FMVSS 208 does not require the weighted 6-year-old dummy. The injury criteria for the weighted 6-year-old dummy were scaled from the 6-year-old. Other than the chest deflection ICPL, the HIC15, Chest g's, and Nij ICPLs are proposed to be the same as the 6-year-old. Readers please consult the report "Development of Improved Injury Criteria for the Assessment of Child Restraint Systems" for a comprehensive scaling methodology and analysis.
The development of these injury criteria and the corresponding ICPLs curves was documented in NHTSA's report "Supplement: Development of Improved Injury Criteria for the Assessment of Advanced Automotive Restraint Systems - II, March 2000 (2)." Also, readers please see NHTSA report "Final Economic Assessment, FMVSS No 208, Advanced Air Bags, May 2000" for a summary of the injury criteria and probability curves.
HIC15 vs HICunlimited
NHTSA's Vehicle Research and Test Center (VRTC) has analyzed FMVSS 213 pulse sled test data and the New Car Assessment Program (NCAP) full scale vehicle tests with a 3-year-old dummy to compare HIC15 to HICunlimited. Figures III-1 and III-2 (adapted from report as shown below) indicate that a linear correlation exists between HIC36 and HIC15. Figure III-1 using the VRTC sled test data shows that HIC15 = 0.5911 * HICunlimited, i.e., HIC15 591 = HICunlimited 1000. Figure III-2 using the NCAP test data shows that HIC15 = 0.6113 * HICunlimited, i.e., HIC15 611 = HICunlimited 1000. Based on these data, the agency's proposed head injury criteria HIC15 with its lower performance limit (570 for 3yo) is slightly more stringent than the current HICunlimited with a performance limit of 1000. The proposed 390 HIC15 for CRABI based on scaling is equivalent to the 570 HIC15 for the 3-year-old dummy. Thus, the proposed HIC15 requirement is also more stringent than 1000 HICunlimited. Readers please see the report "Preliminary Dynamic Evaluation of Proposed 213 Side Impact Test Procedure" for a detailed analysis.
Figure III-1
HIC15 vs HIC unlimited HIC Using VRTC FMVSS 213 Pulse Sled Test Data
Figure III-2
HIC15 vs HIC unlimited HIC Using NCAP Test Data
Summary of ICPL Proposal
Head - The agency is proposing HIC15 to be used to measure head injury. HIC15 was developed from short duration, hard rigid surface, cadaveric head drop data and was designed to minimize skull fracture/brain injury due to head contacts with interior compartment components. The agency proposes HIC15=390 for the 12-month-old CRABI, HIC15=570 for the 3-year-old, and HIC15=700 for the 6-year-old and the weighted 6-year-old dummies. Table III-1 summarizes the ICPL requirements for each child dummy size.
Neck - NHTSA is proposing neck injury criterion Nij. This criterion combines neck axial force (FZ - tension/compression) and neck moment (MY - flexion/extension) into one ICPL. Nij represents four combinations of axial force FZ (tension/compression) and neck moment MY (flexion/extension) to measure four primary types of cervical injuries: tension-extension (NTE), tension-flexion (NTF), compression-extension (NCE), and compression-flexion (NCF). To calculate Nij, each measurement (FZ and MY) recorded by the upper neck load cell is first normalized against the critical intercept values for each specific dummy. The normalized loads and moments can be expressed as: FNZ = FZ / FZCRIT., and MNY =MY / MY CRIT., where FZ CRIT. and MY CRIT. are the critical intercept values. Table III-1 shows the proposed in-position critical values for different child dummies. AMA recommended these critical values. Nij then is the summation of the normalized neck axial force and normalized neck moment at the occipital condyle, i.e., Nij = FNZ + MNY.
NHTSA is proposing that Nij values can not exceed 1.0 at any point in time regardless of the magnitude of axial force and neck moment, i.e., the agency only requires the maximum of (NTE, NTF, NCE, and NCF) can't be greater than 1.0.
NHTSA is not proposing the neck tension and compression limits. Based on NHTSA's recent sled tests and vehicle crash tests with child dummies in child safety seats, most child safety seats failed the additional tension and compression in-position injury limits proposed by AMA for children. However, NASS data and previous published literature indicate that neck injuries in children exposed to FMVSS 213-type conditions are rare. This suggests that the in-position tension and compression limits for children proposed by AMA are too conservative. Therefore, FMVSS 213 does not consider the additional neck tension and compression limits.
Chest Acceleration (chest g's) - The proposed ICPLs for chest g's are: 50 g's for the 12-month-old CRABI, 55 g's for the 3-year-old, and 60 g's for both 6-year-old and weighted 6-year-old.
Chest Deflection - The proposed ICPLs for chest deflection are: 30 mm (1.2") for the 12-month-old CRABI, 34 mm (1.4") for the 3-year-old, 40 mm (1.6") for the 6-year-old, and 42 mm (1.7") for the weighted 6-year-old.
Table III-1 summarizes the proposed FMVSS 213 injury criteria and its ICPLs. Note that FMVSS 208 does not require a weighted 6-year-old dummy. The ICPLs for the weighted 6-year-old dummy are scaled from the injury values of the 6-year-old dummy.
Table III-1
Proposed FMVSS 213 Injury Criteria and Injury Criteria Performance Limits
| Injury Criteria | Hybrid III Child Dummy Size | |||
|---|---|---|---|---|
| 12-Month- Old CRABI |
3-Year-Old | 6-Year-Old | Weighted 6-Year-Old*** |
|
| Head Criterion (HIC15ms) | 390 | 570 | 700 | 700 |
| Neck Criterion (Nij) | 1 | 1 | 1 | 1 |
| Critical Neck Value* | ||||
|
1460 | 2340 | 3096 | 3096 |
|
1460 | 2120 | 2800 | 2800 |
|
43 | 68 | 93 | 93 |
|
17 | 30 | 42 | 42 |
| Thoracic Criteria | ||||
|
50 | 55 | 60 | 60 |
|
30 1.2" |
34 1.4" |
40 1.6" |
42 1.7" |
| Head Excursion ** | ||||
|
720 28" |
720 28" |
720 28" |
720 28" |
|
813 32" |
813 32" |
813 32" |
813 32" |
| Knee Excursion (mm)** | 915 36" |
915 36" |
915 36" |
915 36" |
C. Injury Risk Curves
The injury curves are used to estimate the probability of risk of a fatality or injury at a given injury value. The difference between the probabilities of a given set of crash test injury values and of the proposed ICPLs would be used to assess the benefits of the proposed rulemaking. The following figures and formulas show the injury risk curves for head, neck, and thorax injuries. These injury risk curves are adapted from FVMSS 208. Note that the agency believes that the new proposal would impact only on MAIS 2+ injuries, thus, this section provides only MAIS 2+ through 5+ and fatality injury probability risk curves. The development of original injury probability curves was documented in NHTSA's report "Supplement: Development of Improved Injury Criteria for the Assessment of Advanced Automotive Restraint Systems - II, March 2000 (3)." Also, readers please see NHTSA report "Final Economic Assessment, FMVSS NO 208, Advanced Air Bags, May 2000" for a summary of the injury probability curves.
Head Injury Criterion (HIC15)
The HIC15 probability curves are used to measure the chances that a vehicle occupant would receive certain MAIS head injury at a given HIC value. The analysis uses both variations of Prasad/Metez and Hertz (lognormal) (4) curves to estimate head injury probabilities. These variations were derived by a shifting process - mapping the probabilities at 700 HIC15 to those of 1000 HIC36. The proposed HIC15 ICPL is 390 for CRABI, 570 for 3-year-old, and 700 for both 6- and weighted 6-year-old dummies. The probability risks for these HIC15 values are the same and all equate to the 700 HIC15 level of a 6-year-old (or a weighted 6-year-old). Note that the HIC15 probability curves are the same for the 6-year-old, the weighted 6-year-old, and adults because they have the same 700 HIC15 ICPL.
Prasad/Mertz Probability Curves
Tables III-2 shows the probability risk values that are derived from the variation of the Prasad/Mertz HIC15 curves for the 6-year-old. For children less than 6 years old, the injury probabilities need to be scaled accordingly for children represented by a 3-year-old or 12-month old CRABI. For example, the probability for CRABI at 390 HIC15 is equivalent to that at 570 HIC15 for 3-year-old and 700 HIC15 for 6-year-old. The following are the HIC15 probability formula (derived from the Prasad/Mertz curves) used to generate 6-year-old head probability values in Table III-2 and Figure III-1. These curves are the same for the weighted 6-year-old.
AIS 2+ Percent Injury Probability = [1 / (1 + exp (2.49 +140/HIC - 0.00690*HIC ))] X 100%.
AIS 3++ Percent Injury Probability = [1 / (1 + exp (3.39 +140/HIC - 0.00531*HIC ))] X 100%.
AIS 4+ Percent Injury Probability = [1 / (1 + exp (4.90 +140/HIC - 0.00501*HIC ))] X 100%.
AIS 5+ Percent Injury Probability = [1 / (1 + exp (7.82 +140/HIC - 0.00613*HIC ))] X 100%.
Fatality Percent Injury Probability = [1 / (1 + exp (12.14 +140/HIC - 0.00807*HIC ))] X 100%.
Table III-2
Prasad/Mertz HIC15 Probability Risk Values* for 6-Year-Old Dummy
| HIC15 | MAIS 1 | MAIS 2 | MAIS 3 | MAIS 4 | MAIS 5 | Fatal | No Injury |
|---|---|---|---|---|---|---|---|
| 50 | 1.3% | 0.4% | 0.2% | 0.1% | 0.0% | 0.0% | 98.0% |
| 100 | 7.9% | 2.5% | 1.1% | 0.3% | 0.0% | 0.0% | 88.2% |
| 150 | 16.9% | 5.6% | 2.2% | 0.6% | 0.0% | 0.0% | 74.6% |
| 200 | 26.5% | 9.4% | 3.6% | 0.9% | 0.1% | 0.0% | 59.4% |
| 250 | 34.5% | 14.2% | 5.3% | 1.4% | 0.1% | 0.0% | 44.5% |
| 300 | 39.4% | 19.8% | 7.4% | 1.9% | 0.2% | 0.0% | 31.4% |
| 350 | 40.4% | 25.7% | 9.9% | 2.6% | 0.2% | 0.0% | 21.2% |
| 400 | 38.1% | 31.4% | 12.8% | 3.4% | 0.3% | 0.0% | 13.9% |
| 450 | 33.6% | 36.3% | 16.3% | 4.5% | 0.4% | 0.0% | 8.9% |
| 500 | 28.0% | 39.8% | 20.2% | 5.8% | 0.6% | 0.0% | 5.6% |
| 550 | 22.4% | 41.4% | 24.3% | 7.4% | 0.9% | 0.0% | 3.5% |
| 600 | 17.3% | 41.2% | 28.6% | 9.4% | 1.2% | 0.0% | 2.2% |
| 650 | 13.1% | 39.4% | 32.7% | 11.8% | 1.6% | 0.1% | 1.4% |
| 700 | 9.7% | 36.3% | 36.3% | 14.6% | 2.2% | 0.1% | 0.8% |
| 750 | 7.1% | 32.4% | 39.1% | 17.7% | 3.0% | 0.2% | 0.5% |
| 800 | 5.1% | 28.1% | 40.8% | 21.2% | 4.1% | 0.3% | 0.3% |
| 850 | 3.7% | 23.8% | 41.4% | 25.0% | 5.5% | 0.4% | 0.2% |
| 900 | 2.6% | 19.8% | 40.8% | 28.8% | 7.3% | 0.6% | 0.1% |
| 950 | 1.9% | 16.2% | 39.0% | 32.4% | 9.6% | 0.9% | 0.1% |
| 1000 | 1.3% | 13.1% | 36.3% | 35.4% | 12.5% | 1.3% | 0.0% |
| 1050 | 0.9% | 10.4% | 33.0% | 37.7% | 16.0% | 2.0% | 0.0% |
| 1100 | 0.7% | 8.2% | 29.2% | 38.8% | 20.1% | 3.0% | 0.0% |
| 1150 | 0.5% | 6.5% | 25.4% | 38.6% | 24.7% | 4.4% | 0.0% |
| 1200 | 0.3% | 5.0% | 21.6% | 37.1% | 29.4% | 6.5% | 0.0% |
| 1250 | 0.2% | 3.9% | 18.1% | 34.4% | 33.9% | 9.4% | 0.0% |
| 1300 | 0.2% | 3.0% | 15.0% | 30.8% | 37.5% | 13.5% | 0.0% |
| 1350 | 0.1% | 2.4% | 12.2% | 26.6% | 39.7% | 19.0% | 0.0% |
| 1400 | 0.1% | 1.8% | 9.9% | 22.3% | 39.9% | 26.1% | 0.0% |
| 1450 | 0.1% | 1.4% | 7.9% | 18.1% | 37.9% | 34.6% | 0.0% |
| 1500 | 0.0% | 1.1% | 6.3% | 14.3% | 34.0% | 44.3% | 0.0% |
| 1550 | 0.0% | 0.8% | 5.0% | 11.1% | 28.6% | 54.4% | 0.0% |
| 1600 | 0.0% | 0.6% | 4.0% | 8.4% | 22.8% | 64.2% | 0.0% |
| 1650 | 0.0% | 0.5% | 3.1% | 6.3% | 17.2% | 72.9% | 0.0% |
| 1700 | 0.0% | 0.4% | 2.4% | 4.6% | 12.4% | 80.2% | 0.0% |
| 1750 | 0.0% | 0.3% | 1.9% | 3.4% | 8.6% | 85.8% | 0.0% |
| 1800 | 0.0% | 0.2% | 1.5% | 2.4% | 5.7% | 90.1% | 0.0% |
| 1850 | 0.0% | 0.2% | 1.2% | 1.7% | 3.7% | 93.2% | 0.0% |
| 1900 | 0.0% | 0.1% | 0.9% | 1.2% | 2.4% | 95.3% | 0.0% |
| 1950 | 0.0% | 0.1% | 0.7% | 0.9% | 1.5% | 96.8% | 0.0% |
| 2000 | 0.0% | 0.1% | 0.6% | 0.6% | 0.9% | 97.9% | 0.0% |
Figure III-1
Head Injury Probability vs HIC5 for 6-Year-Old Dummy
(Derived From Prasad/Mertz Curves)
The HIC15 injury probability curves for children represented by the 3-year-old dummy are:
| AIS 2+ Percent Injury Probability | = [1 / (1 + exp (2.49 + 114/HIC - 0.00847*HIC))] X 100% |
| AIS 3+ Percent Injury Probability | = [1 / (1 + exp (3.39 + 114/HIC - 0.00653*HIC))] X 100% |
| AIS 4+ Percent Injury Probability | = [1 / (1 + exp (4.90 + 114/HIC - 0.00616*HIC))] X 100% |
| AIS 5+ Percent Injury Probability | = [1 / (1 + exp (7.82 + 114/HIC - 0.00753*HIC))] X 100% |
| Fatality Percent Injury Probability | = [1 / (1 + exp (12.24 + 114/HIC - 0.00991*HIC))] X 100% |
The HIC15 injury probability curves for children represented by the 12-month-old CRABI are:
| AIS-2+ Percent Injury Probability | = [1 / (1 + exp (2.49+78/HIC - 0.01238*HIC))] X 100% |
| AIS3+ Percent Injury Probability | = [1 / (1 + exp (3.39+78/HIC - 0.00954*HIC))] X 100% |
| AIS4+ Percent Injury Probability | = [1 / (1 + exp (4.90+78/HIC - 0.00900*HIC))] X 100% |
| AIS5+ Percent Injury Probability | = [1 / (1 + exp (7.82+78/HIC - 0.011000*HIC))] X 100% |
| Fatality Percent Injury Probability | = [1 / (1 + exp (12.24+78/HIC - 0.01449*HIC))] X 100% |
Lognormal Probability Curves
Table III-3 and Figure III-2 shows the probability risk values derived from the lognormal curves for children represented by the 6-year-old dummy. These curves are the same as those of weighted 6-year-old and adults. Similarly, the variation of the lognormal curves for children represented by the 3-year-old and 12-month-old CRABI dummies can be derived using the same shifting process. These probability values are shown in Table III-4 and Table III-5, respectively.
Figure III-2
Head Injury Probability vs HIC15 for 6-Year-Old Dummy
(Derived From Lognormal Curves)
Based on Table III-2, the variation of Prasad/Mertz curves, at the HIC15 ICPL level, a 6-year-old child occupant in the frontal crash would have a 89.4 percent chance to receive a MAIS 2-5 non-fatal head injury (at 700 HIC15, add together 36.3% for MAIS 2, 36.3% for MAIS 3, 14.6% for MAIS 4, and 2.2% for MAIS 5) and have about 0.1 percent chance to receive a fatal head injury.
Based on Table III-3, the variation of the lognormal curves, at the ICPL level, a 6-year-old child would have a 40.53 percent chance to receive a MAIS 2-5 non-fatal head injury (at 700 HIC15, add together 24.48% for MAIS 2, 12.21% for MAIS 3, 1.91% for MAIS 4, and 2.13% for MAIS 5), and have about 6.84 percent chance to receive a fatal head injury.
Neck Injury Criteria (Nij)
The formulas for Percent Injury Probability at AIS 2+ through AIS 5+ injury, as a function of Nij values are as follows:
AIS 2+ Percent Injury Probability = [1/ (1 + exp (2.0536 -1.1955*Nij ))] X 100%.
AIS 3+ Percent Injury Probability = [1/ (1 + exp (3.227 - 1.969*Nij ))] X 100%.
AIS 4+ Percent Injury Probability = [1/ (1 + exp (2.693 -1.196*Nij ))] X 100%.
AIS 5+ Percent Injury Probability = [1/ (1 + exp (3.817 - 1.196*Nij ))] X 100%.
Fatality Percent Injury Probability = [1/ (1 + exp (3.817 - 1.196*Nij ))] X 100%. (Same as AIS 5+)
Table III-3
Lognormal HIC15 Probability Risk Values* for 6-Year-Old Dummy
| HIC15 | MAIS 1 | MAIS 2 | MAIS 3 | MAIS 4 | MAIS 5 | Fatal | No Injury |
|---|---|---|---|---|---|---|---|
| 50 | 13.99% | 0.07% | 0.00% | 0.00% | 0.00% | 0.00% | 85.94% |
| 100 | 33.88% | 0.86% | 0.04% | 0.00% | 0.00% | 0.00% | 65.22% |
| 150 | 47.45% | 2.73% | 0.23% | 0.01% | 0.00% | 0.00% | 49.58% |
| 200 | 55.51% | 5.35% | 0.71% | 0.02% | 0.02% | 0.01% | 38.38% |
| 250 | 59.73% | 8.33% | 1.50% | 0.07% | 0.06% | 0.04% | 30.27% |
| 300 | 61.40% | 11.31% | 2.57% | 0.16% | 0.14% | 0.13% | 24.29% |
| 350 | 61.41% | 14.10% | 3.84% | 0.30% | 0.27% | 0.31% | 19.77% |
| 400 | 60.33% | 16.59% | 5.22% | 0.47% | 0.46% | 0.63% | 16.30% |
| 450 | 58.57% | 18.71% | 6.64% | 0.68% | 0.69% | 1.12% | 13.59% |
| 500 | 56.39% | 20.47% | 8.00% | 0.92% | 0.96% | 1.81% | 11.45% |
| 550 | 53.99% | 21.87% | 9.27% | 1.17% | 1.25% | 2.73% | 9.72% |
| 600 | 51.47% | 22.96% | 10.40% | 1.42% | 1.56% | 3.87% | 8.32% |
| 650 | 48.93% | 23.74% | 11.39% | 1.67% | 1.85% | 5.25% | 7.17% |
| 700 | 46.41% | 24.28% | 12.21% | 1.91% | 2.13% | 6.84% | 6.22% |
| 750 | 43.95% | 24.60% | 12.87% | 2.12% | 2.39% | 8.64% | 5.43% |
| 800 | 41.59% | 24.72% | 13.38% | 2.31% | 2.62% | 10.62% | 4.76% |
| 850 | 39.32% | 24.70% | 13.73% | 2.48% | 2.81% | 12.77% | 4.19% |
| 900 | 37.16% | 24.54% | 13.95% | 2.62% | 2.97% | 15.05% | 3.71% |
| 950 | 35.11% | 24.26% | 14.06% | 2.73% | 3.10% | 17.44% | 3.30% |
| 1000 | 33.18% | 23.90% | 14.05% | 2.82% | 3.18% | 19.93% | 2.94% |
| 1050 | 31.36% | 23.46% | 13.95% | 2.89% | 3.24% | 22.47% | 2.63% |
| 1100 | 29.64% | 22.98% | 13.75% | 2.94% | 3.26% | 25.07% | 2.36% |
| 1150 | 28.01% | 22.45% | 13.51% | 2.95% | 3.26% | 27.69% | 2.13% |
| 1200 | 26.50% | 21.88% | 13.19% | 2.96% | 3.24% | 30.31% | 1.92% |
| 1250 | 25.07% | 21.29% | 12.84% | 2.95% | 3.18% | 32.93% | 1.74% |
| 1300 | 23.72% | 20.69% | 12.44% | 2.93% | 3.11% | 35.53% | 1.58% |
| 1350 | 22.46% | 20.07% | 12.02% | 2.89% | 3.02% | 38.10% | 1.44% |
| 1400 | 21.28% | 19.45% | 11.58% | 2.83% | 2.93% | 40.62% | 1.31% |
| 1450 | 20.16% | 18.84% | 11.12% | 2.77% | 2.82% | 43.09% | 1.20% |
| 1500 | 19.11% | 18.23% | 10.65% | 2.71% | 2.69% | 45.51% | 1.10% |
| 1550 | 18.13% | 17.61% | 10.19% | 2.63% | 2.57% | 47.86% | 1.01% |
| 1600 | 17.21% | 17.01% | 9.71% | 2.56% | 2.44% | 50.14% | 0.93% |
| 1650 | 16.34% | 16.43% | 9.24% | 2.48% | 2.30% | 52.36% | 0.85% |
| 1700 | 15.52% | 15.85% | 8.78% | 2.39% | 2.17% | 54.50% | 0.79% |
| 1750 | 14.75% | 15.29% | 8.32% | 2.31% | 2.04% | 56.56% | 0.73% |
| 1800 | 14.03% | 14.75% | 7.87% | 2.22% | 1.91% | 58.55% | 0.67% |
| 1850 | 13.35% | 14.21% | 7.45% | 2.13% | 1.77% | 60.47% | 0.62% |
| 1900 | 12.70% | 13.70% | 7.02% | 2.04% | 1.65% | 62.31% | 0.58% |
| 1950 | 12.10% | 13.19% | 6.62% | 1.95% | 1.52% | 64.08% | 0.54% |
| 2000 | 11.53% | 12.71% | 6.22% | 1.87% | 1.40% | 65.77% | 0.50% |
Table III-4
Lognormal HIC15 Probability Risk Values for 3-Year-Old Dummy
| HIC15 | MAIS 1 | MAIS 2 | MAIS 3 | MAIS 4 | MAIS 5 | Fatal | No Injury |
|---|---|---|---|---|---|---|---|
| 50 | 18.94% | 0.16% | 0.00% | 0.00% | 0.00% | 0.00% | 80.90% |
| 100 | 40.86% | 1.60% | 0.10% | 0.00% | 0.00% | 0.00% | 57.44% |
| 150 | 53.44% | 4.48% | 0.52% | 0.01% | 0.02% | 0.00% | 41.53% |
| 200 | 59.48% | 8.06% | 1.42% | 0.06% | 0.05% | 0.04% | 30.89% |
| 250 | 61.49% | 11.72% | 2.74% | 0.18% | 0.15% | 0.15% | 23.57% |
| 300 | 61.11% | 15.06% | 4.34% | 0.36% | 0.33% | 0.41% | 18.39% |
| 350 | 59.34% | 17.90% | 6.07% | 0.59% | 0.59% | 0.90% | 14.61% |
| 400 | 56.80% | 20.18% | 7.77% | 0.87% | 0.92% | 1.67% | 11.79% |
| 450 | 53.86% | 21.94% | 9.33% | 1.18% | 1.27% | 2.78% | 9.64% |
| 500 | 50.75% | 23.21% | 10.69% | 1.49% | 1.65% | 4.23% | 7.98% |
| 550 | 47.64% | 24.04% | 11.83% | 1.79% | 2.00% | 6.03% | 6.67% |
| 600 | 44.60% | 24.53% | 12.72% | 2.06% | 2.32% | 8.15% | 5.62% |
| 650 | 41.67% | 24.72% | 13.37% | 2.30% | 2.61% | 10.55% | 4.78% |
| 700 | 38.90% | 24.67% | 13.79% | 2.51% | 2.84% | 13.20% | 4.09% |
| 750 | 36.29% | 24.43% | 14.01% | 2.67% | 3.03% | 16.04% | 3.53% |
| 800 | 33.85% | 24.03% | 14.06% | 2.80% | 3.15% | 19.05% | 3.06% |
| 850 | 31.57% | 23.53% | 13.95% | 2.89% | 3.23% | 22.16% | 2.67% |
| 900 | 29.46% | 22.92% | 13.73% | 2.94% | 3.27% | 25.34% | 2.34% |
| 950 | 27.51% | 22.26% | 13.40% | 2.96% | 3.26% | 28.56% | 2.05% |
| 1000 | 25.68% | 21.55% | 13.00% | 2.96% | 3.20% | 31.79% | 1.82% |
| 1050 | 24.00% | 20.82% | 12.53% | 2.93% | 3.12% | 34.99% | 1.61% |
| 1100 | 22.44% | 20.07% | 12.01% | 2.88% | 3.03% | 38.14% | 1.43% |
| 1150 | 21.00% | 19.30% | 11.47% | 2.82% | 2.90% | 41.23% | 1.28% |
| 1200 | 19.66% | 18.54% | 10.90% | 2.75% | 2.75% | 44.25% | 1.15% |
| 1250 | 18.42% | 17.80% | 10.32% | 2.66% | 2.60% | 47.17% | 1.03% |
| 1300 | 17.27% | 17.06% | 9.74% | 2.57% | 2.44% | 49.99% | 0.93% |
| 1350 | 16.21% | 16.34% | 9.16% | 2.46% | 2.29% | 52.70% | 0.84% |
| 1400 | 15.22% | 15.64% | 8.60% | 2.36% | 2.12% | 55.30% | 0.76% |
| 1450 | 14.31% | 14.95% | 8.05% | 2.25% | 1.95% | 57.80% | 0.69% |
| 1500 | 13.45% | 14.30% | 7.51% | 2.14% | 1.80% | 60.17% | 0.63% |
| 1550 | 12.67% | 13.66% | 6.99% | 2.04% | 1.63% | 62.44% | 0.57% |
| 1600 | 11.93% | 13.05% | 6.50% | 1.93% | 1.48% | 64.59% | 0.52% |
| 1650 | 11.24% | 12.46% | 6.03% | 1.82% | 1.34% | 66.63% | 0.48% |
| 1700 | 10.60% | 11.90% | 5.57% | 1.72% | 1.20% | 68.57% | 0.44% |
| 1750 | 10.00% | 11.36% | 5.14% | 1.63% | 1.06% | 70.40% | 0.41% |
| 1800 | 9.45% | 10.85% | 4.73% | 1.53% | 0.94% | 72.13% | 0.37% |
| 1850 | 8.93% | 10.36% | 4.35% | 1.43% | 0.82% | 73.77% | 0.34% |
| 1900 | 8.44% | 9.88% | 3.99% | 1.35% | 0.71% | 75.31% | 0.32% |
| 1950 | 7.99% | 9.44% | 3.65% | 1.26% | 0.60% | 76.77% | 0.29% |
| 2000 | 7.56% | 9.01% | 3.33% | 1.18% | 0.51% | 78.14% | 0.27% |
Table III-5
Lognormal HIC15 Probability Risk Values for 12-Month-Old CRABI
| HIC15 | MAIS 1 | MAIS 2 | MAIS 3 | MAIS 4 | MAIS 5 | Fatal | No Injury |
|---|---|---|---|---|---|---|---|
| 50 | 30.27% | 0.62% | 0.02% | 0.00% | 0.00% | 0.00% | 69.09% |
| 100 | 52.75% | 4.22% | 0.47% | 0.02% | 0.01% | 0.00% | 42.53% |
| 150 | 60.62% | 9.49% | 1.88% | 0.10% | 0.08% | 0.07% | 27.76% |
| 200 | 61.28% | 14.57% | 4.09% | 0.32% | 0.31% | 0.35% | 19.08% |
| 250 | 58.63% | 18.66% | 6.60% | 0.67% | 0.69% | 1.10% | 13.65% |
| 300 | 54.56% | 21.57% | 8.99% | 1.11% | 1.19% | 2.49% | 10.09% |
| 350 | 50.03% | 23.44% | 10.98% | 1.56% | 1.72% | 4.62% | 7.65% |
| 400 | 45.52% | 24.42% | 12.47% | 1.98% | 2.23% | 7.46% | 5.92% |
| 450 | 41.24% | 24.73% | 13.44% | 2.34% | 2.65% | 10.94% | 4.66% |
| 500 | 37.27% | 24.55% | 13.95% | 2.61% | 2.96% | 14.93% | 3.73% |
| 550 | 33.66% | 24.00% | 14.06% | 2.80% | 3.17% | 19.28% | 3.03% |
| 600 | 30.42% | 23.21% | 13.85% | 2.92% | 3.25% | 23.87% | 2.48% |
| 650 | 27.51% | 22.26% | 13.40% | 2.96% | 3.26% | 28.56% | 2.05% |
| 700 | 24.89% | 21.21% | 12.79% | 2.95% | 3.17% | 33.27% | 1.72% |
| 750 | 22.55% | 20.12% | 12.06% | 2.89% | 3.03% | 37.90% | 1.45% |
| 800 | 20.47% | 19.01% | 11.25% | 2.79% | 2.85% | 42.40% | 1.23% |
| 850 | 18.61% | 17.90% | 10.42% | 2.67% | 2.63% | 46.72% | 1.05% |
| 900 | 16.94% | 16.83% | 9.57% | 2.53% | 2.40% | 50.83% | 0.90% |
| 950 | 15.44% | 15.80% | 8.73% | 2.38% | 2.16% | 54.71% | 0.78% |
| 1000 | 14.10% | 14.80% | 7.92% | 2.23% | 1.92% | 58.35% | 0.68% |
| 1050 | 12.90% | 13.85% | 7.16% | 2.06% | 1.69% | 61.75% | 0.59% |
| 1100 | 11.81% | 12.96% | 6.43% | 1.91% | 1.46% | 64.91% | 0.52% |
| 1150 | 10.84% | 12.11% | 5.74% | 1.76% | 1.25% | 67.84% | 0.46% |
| 1200 | 9.96% | 11.32% | 5.11% | 1.62% | 1.05% | 70.54% | 0.40% |
| 1250 | 9.16% | 10.58% | 4.53% | 1.47% | 0.88% | 73.02% | 0.36% |
| 1300 | 8.44% | 9.88% | 3.99% | 1.35% | 0.71% | 75.31% | 0.32% |
| 1350 | 7.79% | 9.24% | 3.50% | 1.22% | 0.56% | 77.41% | 0.28% |
| 1400 | 7.20% | 8.63% | 3.05% | 1.11% | 0.43% | 79.33% | 0.25% |
| 1450 | 6.65% | 8.07% | 2.64% | 1.01% | 0.31% | 81.09% | 0.23% |
| 1500 | 6.17% | 7.54% | 2.28% | 0.90% | 0.21% | 82.70% | 0.20% |
| 1550 | 5.72% | 7.05% | 1.95% | 0.81% | 0.12% | 84.17% | 0.18% |
| 1600 | 5.30% | 6.60% | 1.65% | 0.73% | 0.03% | 85.52% | 0.17% |
| 1650 | 4.93% | 6.17% | 1.38% | 0.66% | 0.00% | 86.74% | 0.15% |
| 1700 | 4.58% | 5.78% | 1.14% | 0.59% | 0.00% | 87.86% | 0.14% |
| 1750 | 4.27% | 5.41% | 0.93% | 0.53% | 0.00% | 88.89% | 0.12% |
| 1800 | 3.98% | 5.07% | 0.74% | 0.47% | 0.00% | 89.82% | 0.11% |
| 1850 | 3.72% | 4.75% | 0.57% | 0.41% | 0.00% | 90.67% | 0.10% |
| 1900 | 3.46% | 4.46% | 0.42% | 0.36% | 0.00% | 91.45% | 0.10% |
| 1950 | 3.24% | 4.18% | 0.28% | 0.33% | 0.00% | 92.16% | 0.09% |
| 2000 | 3.03% | 3.92% | 0.17% | 0.29% | 0.00% | 92.81% | 0.08% |
The Nij values are the normalized numbers adjusted to maintain consistency with respect to the neck injury outcome, thus the Nij probability curves are the same regardless of dummy size. Figure III-3 depicts the neck injury probability vs Nij. Note that the fatality probability curve is the same as the AIS 5+ curve.
Figure III-3
Neck Injury Probability vs Nij
Thorax Injury Criteria
Chest acceleration limits and chest deflection limits are proposed for each child dummy size.
Chest Acceleration
Injury probability as a function of chest acceleration (chest g's) based on a 3 ms clip of the spinal acceleration on a 6-year-old dummy is listed below. The mathematical formulas for the chest g's injury probability curves are the same for the 6-year-old, weighted 6-year-old, and the adults (same as the 50th percentile male curves (5) for FMVSS 208) because the ICPL for these dummies are the same at 60 g's.
The chest acceleration injury probability curves for children represented by the 6-year-old and weighted 6-year-old dummies are:
AIS 2+ Percent Injury Probability = [1 / (1 + exp ( 1.2324 - 0.05760* g) )] X 100%.
AIS 3+ Percent Injury Probability = [1 / (1 + exp (3.1493 - 0.06300* g ) )] X 100%.
AIS 4+ Percent Injury Probability = [1 / (1 + exp (4.3425 - 0.06300* g ) )] X 100%.
AIS 5+ Percent Injury Probability = [1 / (1 + exp (8.7652 - 0.06590* g ) )] X 100%
Fatality Percent Injury Probability = [1 / (1 + exp (8.7652 - 0.06590* g ) )] X 100% (same as AIS 5+ Injury Curve).
Where, g = chest g's.
Figure III-4 depicts the chest injury probability vs chest g's. Note that the fatality probability curve is same as the AIS 5+ curve.
Figure III-4
Chest Injury Probability vs Chest Acceleration (g's) for 6-Year-Old Dummy
The chest acceleration injury probability curves for children represented by the 3-year-old dummy are:
| AIS 2+ Percent Injury Probability | = [1 / (1 + exp (1.2324 - 0.06284*g))] X 100% |
| AIS 3+ Percent Injury Probability | = [1 / (1 + exp (3.1493 - 0.06873*g))] X 100% |
| AIS 4+ Percent Injury Probability | = [1 / (1 + exp (4.3425 - 0.06873*g))] X 100% |
| AIS 5+ Percent Injury Probability | = [1 / (1 + exp (8.7652 - 0.07189*g))] X 100% |
| Fatality Percent Injury Probability | = [1 / (1 + exp (8.7652 - 0.07189*g))] X 100% |
The chest acceleration injury probability curves for children represented by the 12-month-old CRABI are:
| AIS 2+ Percent Injury Probability | = [1 / (1 + exp (1.2324 - 0.06912*g))] X 100% |
| AIS 3+ Percent Injury Probability | = [1 / (1 + exp (3.1493 - 0.07560*g))] X 100% |
| AIS 4+ Percent Injury Probability | = [1 / (1 + exp (4.3425 - 0.07560*g))] X 100% |
| AIS 5+ Percent Injury Probability | = [1 / (1 + exp (8.7652 - 0.07908*g))] X 100% |
| Fatality Percent Injury Probability | = [1 / (1+ exp (8.7652 - 0.07908*g))] X 100% |
Chest Deflection
The chest deflection injury curves for children represented by the weighted 6-year-old, 6-year-old, 3-year-old, and 12-month-old CRABI are derived from the 50th percent male curves (6) by a shifting process. For example, the curves for the 6-year-old dummy were derived by mapping the probability of chest injury at 40 mm (1.6") for the 6-year-old dummy to that at 63 mm (2.5") for 50th percentile male dummy. See FMVSS 208 for the original formula for the chest deflection injury probability curves for 50th percentile males. The followings are the chest deflection injury curves for children represented by the 6-year old dummy:
AIS 2+ Percent Injury Probability = [1 / (1 + exp (1.8706 - 0.06991* d) )] X 100%
AIS 3+ Percent Injury Probability = [1 / (1 + exp (3.7124 - 0.07481* d ) )] X 100%
AIS 4+ Percent Injury Probability = [1 / (1 + exp (5.0952 -0.07481* d ) )] X 100%
AIS 5+ Percent Injury Probability = [1 / (1 + exp (8.8274 - 0.07229* d ) )] X 100%
Fatality Percent Injury Probability = [1 / (1 + exp (8.8274 - 0.07229* d ) )] X 100% (same as MAIS 5+ Injury Curve).
Where, d = chest deflection.
Figure III-5 depicts the chest injury probability vs chest deflection (mm) for children represented by the 6-year-old dummy.
Figure III-5
Chest Injury Probability vs Chest Deflection for 6-Year-Old Dummy
The chest deflection injury probability curves for children represented by the 3-year-old dummy are:
| AIS 2+ Percent Injury Probability | = [1 / (1 + exp (1.8706-0.08225*d))] X 100% |
| AIS 3+ Percent Injury Probability | = [1 / (1 + exp (3.7124-0.08802*d))] X 100% |
| AIS 4+ Percent Injury Probability | = [1 / (1 + exp (5.0952-0.08802*d))] X 100% |
| AIS 5+ Percent Injury Probability | = [1 / (1 + exp (8.8274-0.08505*d))] X 100% |
| Fatality Percent Injury Probability | = [1 / (1 + exp (8.8274-0.08505*d))] X 100% |
The chest deflection injury probability curves for children represented by the 12-month-old CRABI are:
| AIS 2+ Percent Injury Probability | = [1 / (1 + exp (1.8706-0.09322*d))] X 100% |
| AIS 3+ Percent Injury Probability | = [1 / (1 + exp (3.7124-0.09975*d))] X 100% |
| AIS 4+ Percent Injury Probability | = [1 / (1 + exp (5.0952-0.09975*d))] X 100% |
| AIS 5+ Percent Injury Probability | = [1 / (1 + exp (8.8274-0.09639*d))] X 100% |
| Fatality Percent Injury Probability | = [1 / (1 + exp (8.8274-0.09639*d))] X 100% |
The chest deflection injury probability curves for children represented by the weighted 6-year-old dummy are:
| AIS 2+ Percent Injury Probability | = [1 / (1 + exp (1.8706 - 0.06659*d))] X 100% |
| AIS 3+ Percent Injury Probability | = [1 / (1 + exp (3.7124 - 0.07125*d))] X 100% |
| AIS 4+ Percent Injury Probability | = [1 / (1 + exp (5.0952 - 0.07125*d))] X 100% |
| AIS 5+ Percent Injury Probability | = [1 / (1 + exp (8.8274 - 0.06885*d))] X 100% |
| Fatality Percent Injury Probability | = [1 / (1 + exp (8.8274 - 0.06885*d))] X 100% |
In the FMVSS 208, the agency developed a Combined Thoracic Index (CTI), a criterion that combines chest g's and chest deflection, to predict chest injuries. CTI was not required in FMVSS 208. But, for simplifying the complexity of the injury requirements, the Final Economic Assessment for FMVSS 208, Advanced Air bags used the CTI injury curves to estimate the probability of chest injuries. The proposed amendment of FMVSS 213 requires Nij, however, it does not require neck limits as in FMVSS 208, and thus significantly reduce the complexity of the injury criterion requirements. In addition, the chest injury probabilities predicted by CTI curves are comparable to the maximum of the probabilities predicted by chest g's and chest deflection curves. Therefore, this analysis does not use CTI injury curves, instead uses the maximum of injury probabilities predicted by the either the chest g's or chest deflection curves.
D. Proposed Seat Assembly
The agency proposes that the compliance uses a bench seat that represents the production of child safety seats in the today's market. See the accompanying NPRM for a detail discussion.
E. Proposed Crash Pulse
The agency proposes to extend the acceleration from 80 to 90 milliseconds. The extended corridor would not reduce the stringency of the test because the new pulse basically has the same onset rise rate and peak g pressure as the current one. The proposed change would only make it easier to conduct the compliance tests closer to 30 mph.
2 Docket Number NHTSA-2000-7013-3.
3 Docket Number NHTSA-2000-7013-3.
4 See the Final Economic Assessment, FMVSS NO. 208, Advanced Air Bags,
Office of Regulatory Analysis & Evaluation, Plans and Polocy, May 2000.
5 The original chest acceleration probability formula were listed in
the "Final; Economic Assessment, FMVSS NO 208, Advanced Air Bags, May 2000".
6 The original chest acceleration probability formula were listed in
the "Final; Economic Assessment, FMVSS NO 208, Advanced Air Bags, May 2000".