U.S. Department of Transportation

 National Highway Traffic

 Safety Administration

National Automotive Sampling System

Crashworthiness Data System

1994 -1996
National Automotive Sampling System/Crashworthiness Data System 1994-1996 i

Contents

Page

Executive Summary ..................................................... v

1. Introduction .......................................................... 1

Background ........................................................ 1

Objective .......................................................... 1

Vehicles Under Consideration ......................................... 1

CDS Estimates ...................................................... 2

2. Perspective .......................................................... 3

3. Vehicle Crash Data ................................................... 5

Car Size ........................................................... 5

Car Crash Modes and Areas of Damage ............................... 5

Car Crash Severity .................................................. 8

Seating Position of Car Occupants ................................... 10

Functional Class and Size of Light Trucks ............................... 11

Light Truck Crash Modes and Areas of Damage ........................ 12

Light Truck Crash Severity ............................................ 14

Seating Position of Light Truck Occupants .............................. 15

4. Occupant Injury Data ................................................ 17

Crash-Involved Occupants by Injury Severity ........................... 17

Use of Belts ........................................................ 20

Effect of Belt Use on Injury Risk ........................................ 22

Injury Severity and Outcome ......................................... 23

Effect of Alcohol Use on Injury Risk .................................... 27

Body Regions Injured in Traffic Crashes ................................ 30

Belt Use and Body Regions Injured .................................... 35

Injury Contacts .................................................... 38

Occupant Ejection and Entrapment .................................. 43

Appendixes

A. Glossary ........................................................ 49

B. NASS/CDS Sample Design ......................................... 53

C. NASS/CDS Data Elements ......................................... 55

D. CRASHPC and OLDMISSPC Summary ............................... 113

E. Harm Definition .................................................. 115

F. Statistical Methods ............................................... 117
Contents

ii National Automotive Sampling System/Crashworthiness Data System 1994-1996

Tables Page

1. Crash-Involved Towed Cars by Weight Class, 1994-1996 ................... 5

2. Distribution of Towed Car Crash Modes and Areas of Damage, 1994-1996 ... 6

3. Distribution of Towed Cars by Crash Severity (delta-v) and Area of Damage: 

Average per Year, 1994-1996 ......................................... 8

4. Occupant Seating Positions in Towed Cars, 1994-1996 .................... 10

5. Distribution of Towed Light Trucks by Vehicle Class and Size, 1994-1996 ...... 11

6. Distribution of Towed Light Truck Crash Modes and Areas of Damage, 

1994-1996 .......................................................... 12

7. Distribution of Towed Light Trucks by Crash Severity (delta-v) and 

Area of Damage: Average per Year, 1994-1996 . . . . . . . . . . . . . . . . . . . . . . . . . 14

8. Occupant Seating Positions in Towed Light Trucks, 1994-1996 .............. 15

9. Distribution of Crash-Involved Car Occupants 

by Maximum Injury Severity: Average per Year, 1994-1996 . . . . . . . . . . . . . . . . . 18

10. Distribution of Crash-Involved Light Truck Occupants 

by Maximum Injury Severity: Average per Year, 1994-1996 ................. 18

11. Distribution of Crash-Involved Car Occupants by Belt Use 

and Maximum Injury Severity: Average per Year, 1994-1996 ................ 20

12. Distribution of Crash-Involved Light Truck Occupants by Belt Use 

and Maximum Injury Severity: Average per Year, 1994-1996 . . . . . . . . . . . . . . . . 21

13. Distribution of Crash-Involved Car Occupants by Treatment 

and Maximum Injury Severity: Average per Year, 1994-1996 ................ 24

14. Distribution of Crash-Involved Light Truck Occupants by Treatment 

and Maximum Injury Severity: Average per Year, 1994-1996 ................ 25

15. Distribution of Crash-Involved Car Drivers by Age Group 

and Alcohol Use: Average per Year, 1994-1996 . . . . . . . . . . . . . . . . . . . . . . . . . . 28

16. Distribution of Crash-Involved Light Truck Drivers by Age Group 

and Alcohol Use: Average per Year, 1994-1996 .......................... 28

17. Distribution of Crash-Involved Car Drivers by Alcohol Use 

and Maximum Injury Severity: Average per Year, 1994-1996 ................ 29

18. Distribution of Crash-Involved Light Truck Drivers by Alcohol Use 

and Maximum Injury Severity: Average per Year, 1994-1996 . . . . . . . . . . . . . . . . 29

19. Distribution of All Injuries to Crash-Involved Car Occupants 

by Body Region and Severity: Average per Year, 1994-1996 ............... 30

20. Distribution of All Injuries to Crash-Involved Light Truck Occupants 

by Body Region and Severity: Average per Year, 1994-1996 ............... 32

21. Distribution of All Injuries to Crash-Involved Car Occupants 

by Injury Contact and Severity: Average per Year, 1994-1996 . . . . . . . . . . . . . . 38

22. Distribution of All Injuries to Crash-Involved Light Truck Occupants 

by Injury Contact and Severity: Average per Year, 1994-1996 .............. 40

23. Occupant Ejection and Entrapment in Crash-Involved Towed Cars 

by Degree of Ejection, Crash Mode, and Area of Damage: 

Average of Nationally Weighted Counts per Year, 1994-1996 .............. 43

24. Occupant Ejection and Entrapment in Crash-Involved Towed Light Trucks 

by Degree of Ejection, Crash Mode, and Area of Damage: 

Average of Nationally Weighted Counts per Year, 1994-1996 .............. 44
Contents

National Automotive Sampling System/Crashworthiness Data System 1994-1996 iii

Page

25. Injury-Weighted Occupant Ejection and Entrapment Rates for Crash-Involved 

Towed Cars by Degree of Ejection, Crash Mode, and Area of Damage: 

Average of Nationally Weighted Counts per Year, 1994-1996 . . . . . . . . . . . . . . 46

26. Injury-Weighted Occupant Ejection and Entrapment Rates for Crash-Involved 

Towed Light Trucks by Degree of Ejection, Crash Mode, and Area of Damage: 

Average of Nationally Weighted Counts per Year, 1994-1996 . . . . . . . . . . . . . . 47

Figures

1. Crash-Involved Vehicles in the United States, Average per Year, 1994-1996 . . 3

2. Distribution of Towed Car Crash Modes and Areas of Damage, 1994-1996 ... 7

3. Distribution of Towed Car Crashes by Crash Severity and Area of Damage, 

1994-1996 .......................................................... 9

4. Distribution of Crash Modes and Areas of Damage: Comparison of Cars 

vs. Light Trucks, 1994-1996 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

5. Distribution of Crash-Involved Occupant Injuries by Maximum Injury Severity: 

Cars vs. Light Trucks, 1994-1996 ........................................ 19

6. Injury Rates for Crash-Involved Car Occupants by Maximum Injury Severity as a 

Function of Belt Use, 1994-1996 ........................................ 22

7. Annual Incidence of Injured Crash-Involved Car Occupants by Maximum Injury 

Severity and Treatment, 1994-1996 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

8. Distribution of Injuries to Crash-Involved Car Occupants by Affected Body Region 

and Severity of Injury, 1994-1996 ....................................... 34

9. Distribution of Injuries by Body Region to Crash-Involved Car Occupants 

by Belt Usage: Weighted Average per Year, 1994-1996 ................... 36

10. Distribution of Injuries by Body Region to Crash-Involved Light Truck Occupants 

by Belt Usage: Weighted Average per Year, 1994-1996 . . . . . . . . . . . . . . . . . . . 37

11. Distribution of Injuries to Crash-Involved Car Occupants by Injury Contact 

and Severity of Injury, 1994-1996 ....................................... 42

12. Towed Car Occupant Ejection Rates by Crash Mode and Degree of Ejection, 

1994-1996 .......................................................... 45

13. Ejection-Induced Occupant Injury Rates for Crash-Involved Towed Cars by 

Degree of Ejection and Crash Mode, 1994-1996 . . . . . . . . . . . . . . . . . . . . . . . . . 48
iv National Automotive Sampling System/Crashworthiness Data System 1994-1996

Executive Summary

During the period 1994 through 1996, an estimated 11.4 million vehicles each year

were involved in police-reported traffic crashes. Approximately 93 percent of these

were automobiles, pickup trucks, vans, and sport/utility vehicles, collectively referred

to as passenger vehicles. Pickup trucks, vans, and utility vehicles are collectively

referred to as light trucks. Most of these vehicles were not seriously damaged: only 26

percent of them were towed from the crash scene due to damage sustained in the

crash. Approximately 47,000 passenger vehicles were involved in fatal crashes each

year.

This report focuses attention on occupants of those passenger vehicles that were

towed from the crash scene. NHTSA's National Automotive Sampling System (NASS)/

Crashworthiness Data System (CDS) collects detailed information on towed

passenger vehicle crashes, employing trained, professional crash investigation

teams. The in-depth data collection, scientific protocols, and professionalism of

those involved make the NASS/CDS database a valuable resource to many in the

traffic safety community.

NASS data are used by government, industry, and the private sector to conduct

research, identify injury patterns and mechanisms, provide a basis for regulatory

decision making, and provide a means of evaluating the association between

occupant injury and various crash-related characteristics.

Some highlights of the report include:

 Passenger cars comprise the largest segment (about 76 percent) of the

passenger vehicles found in the NASS/CDS, and hence, in police-reported

towaway crashes. In the report, Passenger cars are treated separately from the

remaining vehicles, which have been grouped together as light trucks.

 Occupancy patterns for towed crash-involved cars and light trucks were very

similar: about two-thirds (about 67 percent) of the time, the only occupant of a

towed crash-involved car or light truck was the driver. A front-seat passenger was

present in the car about 21 percent of the time, with passengers in the second

and further seats about 13 percent of the time. For occupants of light trucks, frontseat passengers were present 20 percent of the time, with passengers in the

second and further seats about 17 percent of the time.

 One of the health-care consequences of motor vehicle crashes is the burden on

emergency and health services. About 243,000 occupants of passenger vehicles

were hospitalized each year as a result of police-reported traffic crashes. Another

1,321,000 occupants were transported to a medical facility and released, and

369,000 occupants were treated at the scene of the crash.

 Contact with the steering assembly accounted for about 10 percent of the minor

injuries (AIS 1-2) but about 15 percent of the serious-maximum (AIS 3+) injuries. A

similar pattern was observed for contact with the interior side surface, comprising

7 percent of the minor injuries and 15 percent of serious and greater injuries.
Executive Summary

National Automotive Sampling System/Crashworthiness Data System 1994-1996 v

 Approximately 288,000 injuries to occupants resulted from contacting an air bag.

Around 97 percent were minor injuries, and about 1 percent were serious injuries.

 About 4 percent of the towed cars in crashes rolled over, compared with 16

percent of the towed light trucks.

 Eight percent of car occupants in rollover crashes were ejected; the remaining

crash types exhibited ejection rates in the range of 0.1 to 1.5 percent.

 The belt use rate for all occupants of passenger vehicles was about 75 percent.

 The alcohol involvement rate for drivers of both passenger cars and light trucks in

traffic crashes is highest for the age group 25-34 years.

 The alcohol involvement rate for all drivers of light trucks in traffic crashes is almost

twice that for drivers of passenger cars.
National Automotive Sampling System/Crashworthiness Data System 1994-1996 1

1. Introduction

Background

The National Automotive Sampling System (NASS)—formerly, the National Accident

Sampling System—is the mechanism through which the National Highway Traffic

Safety Administration (NHTSA) collects nationally representative data on motor

vehicle traffic crashes to aid in the development, implementation, and evaluation of

motor vehicle and highway safety countermeasures. The NASS was originally

designed and implemented in 1979 to support highway and motor vehicle safety

programs. The NASS program was reevaluated in the mid-1980s. The evaluation

team concluded that the program should be redesigned to focus on enhanced indepth analyses of passenger vehicle crash protection performance. This

reevaluation resulted in changes that were implemented by NHTSA's National Center

for Statistics and Analysis (NCSA) in January 1988.

To enhance its applicability in addressing crashworthiness issues, the NASS was

divided into two parts: (1) the General Estimates System (GES), which collects data

on an annual sample of approximately 50,000 police-reported traffic crashes; and

(2) the Crashworthiness Data System (CDS), which collects additional detailed

information on an annual sample of approximately 5,000 police-reported traffic

crashes involving passenger vehicles towed from the crash scene due to damage

resulting from the crash. In this report, the term passenger vehicles is used to refer to

all cars, pickup trucks, vans, and sport/utility vehicles with a gross vehicle weight

rating (GVWR) of 10,000 pounds or less. The term light trucks is used to refer to pickup

trucks, vans, and sport/utility vehicles.

Unlike the CDS, the GES does not investigate crashes. Its only source of information is

the police crash report. It does provide the data needed for assessments of the state

of and trends in motor vehicle and traffic safety. An annual report is published each

year that describes the data availability from the NASS/GES and the Fatality Analysis

Reporting System (FARS). The FARS is a census of all fatal crashes that occur in the

United States and Puerto Rico.

Objective

The objective of this report is to illustrate the availability, resolution, and applicability

of crash, vehicle, occupant, and casualty attributes for the characterization of

vehicle crash protection performance on U.S. roads during the years 1994 through

1996, based on the NASS/CDS records for those years.

Vehicles Under Consideration

This report addresses towed passenger cars, pickup trucks, vans, and sport/utility

vehicles under 10,000 pounds GVWR. Sport/utility vehicles include jeeps, truck-based

station wagons, utility vehicles, and other van- or truck-based motor vehicles under

10,000 pounds GVWR that are not cars, pickups, or vans. Motorcycles, bicycles,

horse-drawn carriages, etc., are not included.
Introduction

2 National Automotive Sampling System/Crashworthiness Data System 1994-1996

CDS Estimates

Unless otherwise noted, all the CDS statistics presented in this report are estimates -

not exact counts- generated from a sample of crashes that occurred in the 3-year

period from 1994 through 1996. Descriptions of the CDS sample design and the

procedure used to obtain the data shown in the tables are contained in Appendix B.

Since the CDS is a probability sample, the sampling error of every CDS statistic can

be estimated. Approximate sampling errors for the weighted average counts over

the 1994-1996 period are provided in Appendix F.
National Automotive Sampling System/Crashworthiness Data System 1994-1996 3

2.

Note: For those vehicles where tow status is unknown it is assumed

that the vehicles were not towed. While all vehicles are addressed

by NASS/GES, only towed passenger vehicles are addressed by

NASS/CDS.

Source: NASS/CDS and NASS/GES, 1994-1996.

All Vehicles

11,893,241

100%

Cars

8,005,415

67.3%

Pickups:

1,886,393

15.9%

Vans

726,641

6.1%

Sport/Utility

vehicles:

505,838

4.3%

All Other:

768,954

6.4%

Towed: 150,765 (20.7%)

Towed: 460,863 (24.4%)

Non-towed: 1,425,530 (75.6%)

Towed: 86,489 (11.2%)

Non-towed: 682,465 (88.8%)

Non-towed: 575,876 (79.3%)

Towed: 123,768 (24.5%)

Non-towed: 382,070 (75.5%)

Towed: 2,255,976 (28.2%)

Non-towed: 5,749,439 (71.8%)

Figure 1

Crash-Involved Vehicles in the United States,

Average per Year, 1994-1996

Perspective

A perspective on crash-involved vehicles is provided in Figure 1, which shows the

annual incidence averaged over the years 1994-1996.

The number of vehicles of all body types involved in police-reported crashes each

year in the United States is about 11,400,000; about 93.0 percent of these are

passenger cars, pickups, vans, and sport/utility vehicles. In this report, pickups, vans,

and sport/utility vehicles are collectively referred to as “light trucks.” Each of these

body types is subdivided into towed and non-towed vehicles.
Perspective

4 National Automotive Sampling System/Crashworthiness Data System 1994-1996

The towed vehicles shown in Figure 1 are investigated in the NASS/CDS, because of

interest in the crashworthiness of vehicles involved in the more severe crashes. These

are the subject of the following analyses and illustrations, with emphasis on cars.

During the period 1994-1996, the average number of registered passenger vehicles

per year, as reported by R.L. Polk & Co., was 185,765,664, of which 123,283,749 (66.4

percent) were passenger cars and 62,481,915 (33.6 percent) were light trucks.
National Automotive Sampling System/Crashworthiness Data System 1994-1996 5

3.

Table 1

Crash-Involved Towed Cars by Weight Class, 1994-1996

Weight Class Total Sample

Annual Average

Percent Count

Small (<2,500 lbs) 4,762 33.3% 846,069

Mid-Size (2,500-3,000 lbs) 4,536 35.0% 890,969

Large (>3,000 lbs) 4,631 30.3% 772,190

Unknown Size 256 1.4% 35,066

 Total 14,185 100.0% 2,544,293

Examples of Weight Class:

 Small—Ford Tempo, Mercury Tracer, Saturn, Nissan Sentra, Honda Civic

 Mid-size—Plymouth Sundance, Ford Probe, Honda Prelude, Toyota Celica

 Large—Ford Taurus, Dodge Dynasty, BMW 3 series, Pontiac Grand Prix

Vehicle Crash Data

Car Size

About 2,544,000 cars are towed away from the scene of traffic crashes every year.

Table 1 shows the distribution of these cars by weight class. Passenger cars made up

about 76 percent of all NASS/CDS towed vehicles; the remaining 24 percent were

light trucks (see Table 5).

Car Crash Modes and Areas of Damage

Table 2 and Figure 2 show the distribution of towed cars among the primary crash

modes and areas of damage. Frontal damage in nonrollover car crashes is the most

frequent crash type, accounting for about 58 percent of all towed car crashes. Side

damage and all other nonrollover crash types account for 29 percent and 9

percent, respectively. Rollover car crashes account for the remaining 4 percent.

These crash frequencies do not reflect the distribution of harmful outcomes to the

car occupants. Certain crash types are associated with higher proportions of injury.

For example, although rollover occurs in about 4 percent of towed car crashes, it is

responsible for about 13 percent of the harm-weighted injuries to car occupants in

towed crashes. On the other hand, car crashes with rear damage account for about

9 percent of the cases but are responsible for about 5 percent of the harm-weighted

injuries to occupants (see Table 25).
Vehicle Crash Data

6 National Automotive Sampling System/Crashworthiness Data System 1994-1996

Table 2

Distribution of Towed Car Crash Modes and Areas of Damage, 1994-1996

Crash Mode and

Area of Damage Total Sample

Annual Average

Percent Count

Rollover

 1-3 Quarter Turns 568 2.8% 71,340

 4+ Quarter Turns 443 1.4% 36,254

 End Over End 38 0.1% 1,827

 Total Rollover 1,049 4.3% 109,421

Nonrollover

 Single-Vehicle

 Frontal Damage 1,989 14.2% 362,350

 Side Damage 565 4.1% 104,425

 Rear, Top, or Under Damage 73 1.0% 25,007

 Total Single-Vehicle 2,627 19.3% 491,782

 Multiple-Vehicle

 Frontal Damage 6,196 43.4% 1,104,169

 Side Damage 3,380 25.0% 636,588

 Rear Damage 919 7.9% 200,319

 Top or Under Damage 14 0.1% 2,014

 Total Multiple-Vehicle 10,509 76.4% 1,943,090

 Total Nonrollover 13,136 95.7% 2,434,872

Total Towed Car Crashes 14,185 100.0% 2,544,293

Note: Damage Area “Unknown” has been imputed into the known damage areas.
Vehicle Crash Data

National Automotive Sampling System/Crashworthiness Data System 1994-1996 7

0% 10% 20% 30% 40% 50%

Frequency

Other

Rear

Side

Frontal

Other

Side

Frontal

Rollover

Single-Vehicle

Multiple-Vehicle

Nonrollover

Figure 2

Distribution of Towed Car Crash Modes 

and Areas of Damage, 1994-1996

Note: The "Other" category for single-vehicle crashes includes rear, top,

and under damage. For multiple-vehicle crashes, "Other" includes top

and under damage.

Source: NASS/CDS, 1994-1996.
Vehicle Crash Data

8 National Automotive Sampling System/Crashworthiness Data System 1994-1996

Note: The “Other” category for single-vehicle crashes includes

rear, top, and under damage. For multiple-vehicle crashes,

“Other” includes top and under damage.

Source: NASS/CDS, 1994-1996.
Vehicle Crash Data

National Automotive Sampling System/Crashworthiness Data System 1994-1996 9

Table 3

Distribution of Towed Cars by Crash Severity (delta-v) and Area of Damage:

Average per Year, 1994-1996

Area of

Damage

Crash Frequency by Crash Severity*

1-10 mph 11-20 mph 21-30 mph 31-40 mph >40 mph Unknown Total

Front 217,353 368,872 57,659 6,991 1,477 382,295 1,034,646

33.3% 56.5% 8.8% 1.1% 0.2% 36.9% 40.7%

Side 144,746 148,240 16,480 5,753 242 218,918 534,377

45.9% 47.0% 5.2% 1.8% 0.1% 41.0% 21.0%

Rear 31,131 61,872 11,587 1,303 367 44,579 150,840

29.3% 58.2% 10.9% 1.2% 0.3% 29.6% 5.9%

Other 0 0 0 0 0 68,925 68,925

-- -- -- -- -- 100.0% 2.7%

Unknown 4,753 3,542 117 0 0 747,092 755,505

56.5% 42.1% 1.4% 0.0% 0.0% 98.9% 29.7%

 Total 397,983 582,526 85,843 14,047 2,086 1,461,809 2,544,293

36.8% 53.8% 7.9% 1.3% 0.2% 57.5% 100.0%

*For each area of damage and known crash severity, the first data row shows the number of vehicles, and the

second row shows the percentage of the total number of vehicles in that row for which crash severities were

known. For the “Unknown” column, the second data row shows the percentage of the total for each area of

damage. For the “Total” column, the second data row shows the percentage of the grand total. NA = not

available.

Car Crash Severity

Crash severity (delta-v in miles per hour) for cars varies generally in the range from 1

to 50 mph. Table 3 shows the distribution of towed cars by severity and area of

damage. No crash severity, in terms of delta-v, can be defined for rollover crashes.

Figure 3 illustrates the primary aspects of this distribution.

Crash frequency rises sharply to a peak located between 11 and 20 mph, as shown

in Figure 3. This frequency drops sharply following the peak; cumulative frequency

beyond 40 mph is about 0.2 percent. The same general pattern holds for all areas of

damage in nonrollover crashes: front, side, and rear.

Great caution is recommended in the use and interpretation of crash severity data,

for two reasons: (a) the large number of unknowns; and (b) the sharp reduction in

the number of available cases as crash severity increases. For “Unknown” area of

damage in Table 3, crash severity was calculated using the missing vehicle

reconstruction algorithm (see Appendix E, “CRASHPC and OLDMISSPC Summary”).

Area of damage “other” includes top and undercarriage, which are outside the

scope of the reconstruction algorithm.
Vehicle Crash Data

10 National Automotive Sampling System/Crashworthiness Data System 1994-1996

Note: Data taken from Table 3 (percentage of the total number

of vehicles for which crash severities were known).

0% 10% 20% 30% 40% 50% 60%

Frequency

> 40

31 - 40

21 - 30

11 - 20

1 - 10

Delta-V

Damage Area

Front

Side

Rear

Figure 3

Distribution of Towed Car Crashes by Crash Severity

and Area of Damage, 1994-1996

Due to the sharp rise of outcome severity as crash severity increases, the distribution

of injuries to car occupants vs. crash severity differs markedly from the distribution of

the crash frequency. Specifically, the injury distribution rises to a peak much faster,

and drops much more slowly thereafter, than does the crash frequency distribution.

For example, the injury proportions (not shown) in the five crash severity intervals

used in Table 3 and Figure 3 are 10 percent, 37 percent, 28 percent, 16 percent, and

8 percent for frontal impacts, compared with the corresponding crash proportions of

33 percent, 57 percent, 9 percent, 1 percent, and about 0 percent. However,

although it is true that the injury proportions exceed the corresponding crash

proportions at high crash severities, it is also true that the majority of the injuries occur

at severities under 40 mph. For example, in frontal impacts 92 percent of the injuries

to occupants occur at severities under 40 mph; the cumulative injury proportion

under 40 mph is 97 percent for side impacts and 98 percent for rear impacts.
Vehicle Crash Data

National Automotive Sampling System/Crashworthiness Data System 1994-1996 11

Table 4

Occupant Seating Positions in Towed Cars, 1994-1996

Car Occupants Total Sample

Annual Average

Percent Count

Drivers 14,146 66.7% 2,532,969

Right Front Passengers 5,064 20.5% 780,160

Second Seat Passengers 3,221 11.8% 448,201

Other Passengers 287 1.0% 36,774

 Total 22,718 100.0% 3,798,104

Seating Position of Car Occupants

Every year, approximately 3.8 million people are involved in crashes as occupants of

towed cars. Table 4 shows the distribution of occupant seating positions for towed

cars from 1994 through 1996.

The distribution pattern—about 67 percent drivers, 21 percent right front passengers,

and 12 percent all other—is roughly the same as for all cars regardless of crash

involvement.
Vehicle Crash Data

12 National Automotive Sampling System/Crashworthiness Data System 1994-1996

Table 5

Distribution of Towed Light Trucks by Vehicle Class and Size, 1994-1996

Vehicle Category and Size Total Sample

Annual Average

Percent Count

Compact Pickup 1,345 29.4% 231,107

Standard Pickup 1,292 21.0% 165,241

Unknown Size Pickup 44 0.8% 6,163

Minivan 734 14.1% 110,595

Standard Van 429 9.5% 74,723

Unknown Size Van 36 0.4% 3,192

Compact Utility Vehicle 1,038 20.3% 159,594

Standard Utility Vehicle 247 4.2% 33,066

Unknown Size Utility Vehicle 12 0.2% 1,709

 Total 5,177 100.0% 785,390

Functional Class and Size of Light Trucks

About 785,000 light trucks (pickups, vans, and sport/utility vehicles) under 10,000

pounds gross vehicle weight rating are towed away from the scene of traffic crashes

every year. Table 5 shows the distribution of these vehicles by functional class and

size. The annual average for these vehicles is 24 percent of all NASS/CDS towed

vehicles. The remaining 76 percent are cars.
Vehicle Crash Data

National Automotive Sampling System/Crashworthiness Data System 1994-1996 13

Table 6

Distribution of Towed Light Truck Crash Modes and Areas of Damage, 1994-1996

Crash Mode and

Area of Damage Total Sample

Annual Average

Percent Count

Rollover

 1-3 Quarter Turns 613 10.0% 78,439

 4+ Quarter Turns 444 5.4% 42,570

 End Over End 16 0.1% 450

 Total Rollover 1,073 15.5% 121,459

Nonrollover

 Single-Vehicle

 Frontal Damage 679 17.3% 135,613

 Side Damage 140 3.0% 23,210

 Rear, Top, or Under Damage 14 0.2% 1,918

 Total Single-Vehicle 833 20.5% 160,741

 Multiple-Vehicle

 Frontal Damage 2,380 43.2% 339,519

 Side Damage 692 15.7% 123,457

 Rear Damage 196 5.1% 40,174

 Top or Under Damage 3 0.0% 40

 Total Multiple-Vehicle 3,271 64.1% 503,190

 Total Nonrollover 4,104 84.5% 663,931

Total Crashes 5,177 100.0% 785,390

Light Truck Crash Modes and Areas of Damage

Crash mode and area of damage distributions for towed light trucks involved in

crashes are generally similar to those for towed cars, except for rollover crashes. The

proportion of rollovers for light trucks is 3 to 4 times that for passenger cars. Table 6

shows the distribution of towed light trucks among the primary crash modes and

areas of damage.
Vehicle Crash Data

14 National Automotive Sampling System/Crashworthiness Data System 1994-1996

Note: The “Other” category for single-vehicle crashes includes rear, top, and under damage.

For multiple-vehicle crashes, “Other” includes top and under damage.

0% 10% 20% 30% 40% 50%

Frequency

Other

Rear

Side

Frontal

Other

Side

Frontal

Rollover

Nonrollover

Single-Vehicle

Multiple-Vehicle

Light Trucks

Cars

Figure 4 shows the distribution of crash modes and areas of damage for towed light

trucks, compared with the distribution for towed cars for the years 1994 through 1996.

Most of the observations for car crash frequencies and injury as a function of crash

mode and area of damage are also valid for these vehicles. Rollover is the major

exception: rollover crashes for light trucks are both more frequent than car rollover

crashes (16 percent and 4 percent, respectively) and result in a greater proportion of

harmful outcomes to the vehicle occupants (37 percent and 13 percent,

respectively). The proportion of harm-weighted injuries (37 percent) associated with

rollover crashes is the average for three vehicle classes -pickups, vans, and

sport/utility vehicles (see Table 26). For these three classes the proportion of harmful

outcomes varies significantly: rollover accounts for approximately 37 percent of all

harm associated with pickups, 29 percent for vans, and 45 percent for sport/utility

vehicles

Figure 4

Distribution of Crash Modes and Areas of Damage:

Comparison of Cars vs. Light Trucks, 1994-1996
Vehicle Crash Data

National Automotive Sampling System/Crashworthiness Data System 1994-1996 15

Table 7

Distribution of Towed Light Trucks by Crash Severity (delta-v)

and Area of Damage: Average per Year, 1994-1996

Area of Damage

Crash Frequency by Crash Severity*

1-10 mph 11-20 mph 21-30 mph 31-40 mph >40 mph Unknown Total

Front 67,304 81,479 17,753 3,073 1,185 140,678 311,472

39.4% 47.7% 10.4% 1.8% 0.7% 45.2% 39.7%

Side 39,068 20,333 3,609 129 16 53,728 116,883

61.9% 32.2% 5.7% 0.2% 0.0% 46.0% 14.9%

Rear 5,021 10,331 364 37 0 10,691 26,444

31.9% 65.6% 2.3% 0.2% 0.0% 40.4% 3.4%

Other 0 0 0 0 0 39,652 39,652

-- -- -- -- -- 100.0% 5.0%

Unknown 150 406 11 0 0 290,372 290,940

26.4% 71.5% 1.9% 0.0% 0.0% 99.8% 37.0%

 Total 111,543 112,549 21,737 3,239 1,201 535,121 785,390

44.6% 45.0% 8.7% 1.3% 0.5% 68.1% 100.0%

Light Truck Crash Severity

Table 7 shows the distribution of towed light truck crashes by crash severity (delta-v in

miles per hour) and area of damage. Most of the observations made for towed car

crash frequencies and injuries to occupants as a function of crash severity are also

valid for these vehicles; the same general patterns are observed. For example, for

frontal impact, the injury proportions (not shown) in the five crash severity intervals

used in Table 7 are 7 percent, 27 percent, 29 percent, 18 percent, and 20 percent

for frontal impacts, and the corresponding crash proportions are 39 percent, 48

percent, 10 percent, 2 percent, and less than 1 percent.

A large majority of the injuries to occupants in towed light truck crashes occur at

crash severities under 40 mph. For example, in frontal impacts 80 percent of the

injuries occur at severities under 40 mph. The cumulative injury proportion under 40

mph is 100 percent for both side and rear impacts.

The comment made in connection with car crash severities is even more important

for these vehicles: great caution is recommended in the use and interpretation of

crash severity data, for two reasons: (a) the large number of unknowns; and (b) the

sharp reduction of the number of available cases as crash severity increases. For

“Unknown” area of damage in Table 7, crash severity was calculated using the

missing vehicle reconstruction algorithm.
Vehicle Crash Data

16 National Automotive Sampling System/Crashworthiness Data System 1994-1996

Table 8

Occupant Seating Positions in Towed Light Trucks, 1994-1996

Vehicle Occupants Total Sample

Annual Average

Percent Count

Drivers 5,156 63.4% 776,920

Right Front Passengers 1,726 19.9% 244,121

Second Seat Passengers 805 7.5% 92,409

Other Passengers 604 9.1% 111,064

 Total 8,291 100.0% 1,224,514

Seating Position of Light Truck Occupants

Approximately 1,225,000 people are involved in crashes as occupants of towed light

trucks every year. Table 8 shows the distribution of occupant seating positions for

these vehicles from 1994 through 1996.

The distribution pattern—about 63 percent drivers, 20 percent right front passengers,

and 17 percent all other—is roughly the same as for all light trucks regardless of crash

involvement. It is also similar to the corresponding distribution for towed car crashes

(Table 4).
National Automotive Sampling System/Crashworthiness Data System 1994-1996 17

4. Occupant Injury Data

Crash-Involved Occupants by Injury Severity

Approximately 3,800,000 occupants are involved in towed car crashes every year.

About 49 percent of them are uninjured, and 51 percent are injured at various

severity levels. Similarly, about 1,225,000 occupants are involved in towed light truck

crashes per year, with about 55 percent uninjured and 45 percent injured.

Given that each injured occupant usually has more than one injury, the severity of

the occupant's most harmful injury is used to characterize the seriousness of the

injuries resulting from the crash. The Abbreviated Injury Scale (AIS) is used to

compare injury severities, as follows:

AIS Severity of Injury

0 Not injured

1 Minor

2 Moderate

3 Serious

4 Severe

5 Critical

6 Maximum 

7 Injured, Severity

Unknown

The AIS scale reflects primarily the threat to life: approximately 99 percent for AIS=6;

about 51 percent for AIS=5; about 24 percent for AIS=4; declining rapidly to almost 0

percent for AIS=1. However, the scale is also used to reflect the gravity of

consequences for survivors.

The distribution of injury severities for injured crash-involved occupants is shown in

Table 9 for cars and in Table 10 for light trucks. The two distributions are compared in

Figure 5, where it is evident that there are no major differences at any given level of

injury severity.

Occupants coded as “unknown if injured” have been excluded from the detail in

Tables 9 through 14, but have been included in the “Total” rows to reflect the total

number of occupants involved in towed passenger vehicle crashes.
Occupant Injury Data

18 National Automotive Sampling System/Crashworthiness Data System 1994-1996

Table 9

Distribution of Crash-Involved

Car Occupants by Maximum Injury Severity:

Average per Year, 1994-1996

Maximum AIS Rating Count Percent

Not Injured (0) 1,863,648 49.1%

Minor (1) 1,443,812 38.0%

Moderate (2) 151,919 4.0%

Serious (3) 64,479 1.7%

Severe (4) 13,943 0.4%

Critical (5) 9,540 0.3%

Maximum (6) 3,364 0.1%

 Total, Known Severity 3,550,706 93.5%

Injured, Severity Unknown (7) 207,341 5.5%

 Total 3,798,104 100.0%

Table 10

Distribution of Crash-Involved

Light Truck Occupants by Maximum Injury Severity:

Average per Year, 1994-1996

Maximum AIS Rating Count Percent

Not Injured (0) 675,165 55.1%

Minor (1) 403,107 32.9%

Moderate (2) 51,367 4.2%

Serious (3) 17,490 1.4%

Severe (4) 6,225 0.5%

Critical (5) 3,156 0.3%

Maximum (6) 1,601 0.1%

 Total, Known Severity 1,158,111 94.6%

Injured, Severity Unknown (7) 57,770 4.7%

 Total 1,224,514 100.0%
Occupant Injury Data

National Automotive Sampling System/Crashworthiness Data System 1994-1996 19

0.0%

0.5%

1.0%

1.5%

2.0%

Percent of Occupants

Serious (3) Severe (4) Critical (5) Maximum (6)

Maximum AIS Rating

Cars

Light Trucks

0%

10%

20%

30%

40%

50%

60%

Percent of Occupants

Not Injured (0) Minor (1) Moderate (2)

Maximum AIS Rating

Cars

Light Trucks

Figure 5

Distribution of Crash-Involved Occupant Injuries

by Maximum Injury Severity: Cars vs. Light Trucks, 1995-1996
Occupant Injury Data

20 National Automotive Sampling System/Crashworthiness Data System 1994-1996

Table 11

Distribution of Crash-Involved Car Occupants by Belt Use

and Maximum Injury Severity: Average per Year, 1994-1996

Belt

Use

Frequency of Injury by Maximum AIS Rating*

Not Injured

(0)

Minor

(1)

Moderate

(2)

Serious

(3)

Severe

(4)

Critical

(5)

Maximum

(6)

Injured,

Severity

Unknown (7) Total

None 267,314 372,119 64,938 29,997 7,695 5,514 1,650 27,856 789,094

17.6% 27.1% 45.4% 50.6% 58.4% 62.9% 65.0% 25.1% 24.3%

Automatic Belt 327,889 244,606 27,057 12,451 2,769 1,169 385 20,416 636,988

21.5% 17.8% 18.9% 21.0% 21.0% 13.3% 15.2% 18.4% 19.6%

Manual Belt 862,436 747,911 50,379 16,788 2,584 2,029 472 62,266 1,748,457

56.7% 54.5% 35.2% 28.3% 19.6% 23.2% 18.6% 56.2% 53.8%

Belt With

Child Seat

64,747 8,933 752 18 138 51 31 315 74,985

4.3% 0.7% 0.5% 0.0% 1.0% 0.6% 1.2% 0.3% 2.3%

 Total,

 Restrained

1,255,072 1,001,450 78,188 29,257 5,491 3,249 888 82,997 2,460,430

82.4% 72.9% 54.6% 49.4% 41.6% 37.1% 35.0% 74.9% 75.7%

 Total Known 1,522,386 1,373,569 143,126 59,254 13,186 8,763 2,538 110,853 3,249,524

81.7% 95.1% 94.2% 91.9% 94.6% 91.8% 75.4% 53.5% 85.6%

Unknown 341,262 70,244 8,793 5,225 758 778 826 96,487 548,580

18.3% 4.9% 5.8% 8.1% 5.4% 8.2% 24.6% 46.5% 14.4%

 Total 1,863,648 1,443,813 151,919 64,479 13,944 9,541 3,364 207,340 3,798,104

49.1% 38.0% 4.0% 1.7% 0.4% 0.3% 0.1% 5.5% 100.0%

*For each known belt use category, the first data row shows the number of injuries and the second row shows the percentage of the

“Total Known” in that column. For the “Total Known” and “Unknown” belt use categories, the first row shows the number of injuries

and the second row shows the percentage of the column total. For the column totals, the first row shows the number of injuries and

the second row shows the percentage of the total number of injuries. The row totals include the number of “unknown if injured”.

Use of Belts

The annual distribution of injuries to crash-involved car occupants by maximum injury

severity and belt use is shown in Table 11. A similar joint distribution is shown in

Table 12 for crash-involved light truck occupants.
Occupant Injury Data

National Automotive Sampling System/Crashworthiness Data System 1994-1996 21

Table 12

Distribution of Crash-Involved Light Truck Occupants by Belt Use

and Maximum Injury Severity: Average per Year, 1994-1996

Belt

Use

Frequency of Injury by Maximum AIS Rating*

Not Injured

(0)

Minor

(1)

Moderate

(2)

Serious

(3)

Severe

(4)

Critical

(5)

Maximum

(6)

Injured,

Severity

Unknown (7) Total

None 107,905 138,722 24,137 11,080 4,819 2,393 659 11,814 307,417

19.7% 35.9% 49.7% 66.6% 82.1% 80.3% 62.2% 33.5% 29.2%

Automatic Belt 2,318 1,577 406 17 0 0 0 0 4,318

0.4% 0.4% 0.8% 0.1% 0.0% 0.0% 0.0% 0.0% 0.4%

Manual Belt 426,032 244,583 23,916 5,499 1,050 586 400 23,333 725,857

77.6% 63.3% 49.3% 33.0% 17.9% 19.7% 37.8% 66.2% 69.0%

Belt With

Child Seat

12,432 1,565 69 45 0 0 0 112 14,222

2.3% 0.4% 0.1% 0.3% 0.0% 0.0% 0.0% 0.3% 1.4%

 Total,

 Restrained

440,782 247,725 24,391 5,561 1,050 586 400 23,445 744,397

80.3% 64.1% 50.3% 33.4% 17.9% 19.7% 37.8% 66.5% 70.8%

 Total Known 548,687 386,447 48,528 16,641 5,869 2,979 1,059 35,259 1,051,814

81.3% 95.9% 94.5% 95.2% 94.3% 94.4% 66.1% 61.0% 85.9%

Unknown 126,480 16,661 2,840 848 355 176 543 22,512 172,700

18.7% 4.1% 5.5% 4.8% 5.7% 5.6% 33.9% 39.0% 14.1%

 Total 675,167 403,108 51,368 17,489 6,224 3,155 1,602 57,771 1,224,514

55.1% 32.9% 4.2% 1.4% 0.5% 0.3% 0.1% 4.7% 100.0%

*For each known belt use category, the first data row shows the number of injuries and the second row shows the percentage of the

“Total Known” in that column. For the “Total Known” and “Unknown” belt use categories, the first row shows the number of injuries

and the second row shows the percentage of the column total. For the column totals, the first row shows the number of injuries and

the second row shows the percentage of the total number of injuries. The row totals include the number of “unknown if injured.”

Overall, belt use is approximately 76 percent for passenger car occupants and

71 percent for occupants of light trucks. These belt use rates are in agreement with

the belt use rates obtained by individual state surveys reported to NHTSA each year.

Not all states report belt usage rates each year. Therefore, to calculate the national

safety belt use rate from the individual state use rates, each state's most recent rate

is weighted by the state's proportion of the total U.S. population. Average state belt

use rates were reported as 66 percent in 1993, 67 percent in 1994, and 68 percent in

1995.
Occupant Injury Data

22 National Automotive Sampling System/Crashworthiness Data System 1994-1996

0%

10%

20%

30%

40%

50%

60%

Crash-Involved Occupants

Not Injured (0) Minor (1) Moderate (2) Serious-Maximum (3-6)

Unbelted

Belted

Maximum AIS

Effect of Belt Use on Injury Risk

It is evident from Tables 11 and 12 that safety belt use reduces the risk of injury,

especially serious injury. This is illustrated in Figure 6 for crash-involved car occupants.

In this figure, AIS ratings 3, 4, 5, and 6 have been grouped together as

“Serious-Maximum” in order to deal with the small sample sizes at these high

severities. As seen in Figure 6, the risk of injury (expressed in injured people per 100

crash-involved car occupants) for occupants using belts is lower than that for

unbelted occupants. Moreover, this advantage appears to increase as the injury

severity increases.

A word of caution is necessary when interpreting the much lower risk associated with

belted versus unbelted occupants at high injury severities. It is likely that belted

occupants, who usually have a higher awareness of safety than the unbelted, are

also the occupants who usually avoid crashes of high severities. Thus, the advantage

of belted occupants may be in part due to the fact that such occupants are

exposed to lower crash severities, in addition to the crash protection provided by the

belts.

Figure 6

Injury Rates for Crash-Involved Car Occupants by Maximum

Injury Severity as a Function of Belt-Use, 1994-1996
Occupant Injury Data

24 National Automotive Sampling System/Crashworthiness Data System 1994-1996

Injury Severity and Outcome

As discussed above (see Table 9), not all crash deaths are associated with

untreatable injuries (AIS=6). Rather, the probability of death increases sharply with

injury severity, and many fatalities occur as a result of one or more injuries that are

generally considered survivable. Crash injury outcomes—fatality, hospitalization,

needed emergency medical care, first aid treatment, and no treatment

needed—are generally a function of the severity of an occupant's most severe

injury, plus other factors, such as the number, severity, and type of additional injuries;

the person's age and overall health; extrication time; etc.

The primary determinant of an outcome is the maximum injury severity. Table 13

shows the distribution of injuries to crash-involved car occupants according to the

AIS values of maximum injury severity and the pertinent outcomes of maximum injury

severities. This table also includes the number of days an occupant was hospitalized

for injuries sustained in the crash as a result of the crash. An occupant may be

hospitalized for observation or due to a pre-existing medical condition, as directed

by the attending physician, without having received any injuries in the crash. 

Fatal injuries with AIS=1 are the result of incomplete medical information by which to

code the data. A similar distribution is shown in Table 14 for crash-involved light truck

occupants.
Occupant Injury Data

National Automotive Sampling System/Crashworthiness Data System 1994-1996 25

Table 13

Distribution of Crash-Involved Car Occupants by Treatment

and Maximum Injury Severity: Average per Year, 1994-1996

Treatment

Frequency of Injury by Maximum AIS Rating*

Not Injured

(0)

Minor

(1)

Moderate

(2)

Serious

(3)

Severe

(4)

Critical

(5)

Maximum

(6)

Injured,

Severity

Unknown (7) Total

None 1,755,391 341,630 4,690 0 0 0 0 38,918 2,147,728

81.7% 15.9% 0.2% 0.0% 0.0% 0.0% 0.0% 1.8% 56 5%

Treated

at Scene

21,832 223,483 10,138 538 0 0 0 33,266 289,777

7.5% 77.1% 3.5% 0.2% 0.0% 0.0% 0.0% 11.5% 7 6%

Transported

and Released

76,662 815,911 75,124 12,833 81 16 0 49,492 1,030,895

7.4% 79.1% 7.3% 1.2% 0.0% 0.0% 0.0% 4.8% 27 1%

Hospitalized

 1-2 Days

3,330 40,439 34,389 15,663 2,568 533 0 3,053 99,975

3.3% 40.4% 34.4% 15.7% 2.6% 0.5% 0.0% 3.1% 2 6%

 3-7 Days

326 8,599 21,098 17,990 4,269 1,145 0 774 54,202

0.6% 15.9% 38.9% 33.2% 7.9% 2.1% 0.0% 1.4% 1 4%

 8-14 Days

43 268 3,217 10,294 1,759 1,433 0 29 17,044

0.3% 1.6% 18.9% 60.4% 10.3% 8.4% 0.0% 0.2% 0 4%

 15-30 Days

0 327 1,684 3,726 1,237 999 0 33 8,007

0.0% 4.1% 21.0% 46.5% 15.4% 12.5% 0.0% 0.4% 0 2%

 >30 Days

0 38 160 1,048 724 504 27 0 2,499

0.0% 1.5% 6.4% 41.9% 29.0% 20.2% 1.1% 0.0% 0.1%

Fatal 0 1,077 1,272 2,362 3,306 4,909 3,338 2,912 19,177

0.0% 5.6% 6.6% 12.3% 17.2% 25.6% 17.4% 15.2% 0.5%

Unknown 6,064 12,040 147 24 0 0 0 78,863 128,800

4.7% 9.3% 0.1% 0.0% 0.0% 0.0% 0.0% 61.2% 3.4%

 Total 1,863,648 1,443,812 151,919 64,479 13,943 9,540 3,364 207,341 3,798,104

49.1% 38.0% 4.0% 1.7% 0.4% 0.3% 0.1% 5.5% 100.0%

*For each treatment category, the first data row shows the number of injuries and the second row shows the percentage of the row

total. The row totals include the number of “unknown if injured.”
Occupant Injury Data

26 National Automotive Sampling System/Crashworthiness Data System 1994-1996

Table 14

Distribution of Crash-Involved Light Truck Occupants by Treatment

and Maximum Injury Severity: Average per Year, 1994-1996

Treatment

Frequency of Injury by Maximum AIS Rating*

Not Injured

(0)

Minor

(1)

Moderate

(2)

Serious

(3)

Severe

(4)

Critical

(5)

Maximum

(6)

Injured,

Severity

Unknown (7) Total

None 646,139 87,387 60 0 0 0 0 17,652 752,000

85.9% 11.6% 0.0% 0.0% 0.0% 0.0% 0.0% 2.3% 61 4%

Treated

at Scene

15,165 57,849 1,509 41 0 0 0 4,883 79,522

19.1% 72.7% 1.9% 0.1% 0.0% 0.0% 0.0% 6.1% 6 5%

Transported

and Released

11,329 240,825 26,066 1,477 0 0 0 9,957 289,653

3.9% 83.1% 9.0% 0.5% 0.0% 0.0% 0.0% 3.4% 23 7%

Hospitalized

 1-2 Days

392 12,142 14,412 3,769 1,423 157 0 1,658 34,001

1.2% 35.7% 42.4% 11.1% 4.2% 0.5% 0.0% 4.9% 2 8%

 3-7 Days

42 3,154 5,267 6,080 1,422 141 0 32 16,138

0.3% 19.5% 32.6% 37.7% 8.8% 0.9% 0.0% 0.2% 1 3%

 8-14 Days

6 110 1,829 2,793 989 285 0 4 6,016

0.1% 1.8% 30.4% 46.4% 16.4% 4.7% 0.0% 0.1% 0 5%

 15-30 Days

0 25 1,748 1,970 288 301 0 24 4,355

0.0% 0.6% 40.1% 45.2% 6.6% 6.9% 0.0% 0.6% 0 4%

 >30 Days

0 0 120 359 275 152 3 0 908

0.0% 0.0% 13.2% 39.5% 30.3% 16.7% 0.3% 0.0% 0.1%

Fatal 0 529 325 983 1,828 2,120 1,598 1,836 9,220

0.0% 5.7% 3.5% 10.7% 19.8% 23.0% 17.3% 19.9% 0.8%

Unknown 2,093 1,086 30 18 0 0 0 21,726 32,700

6.4% 3.3% 0.1% 0.1% 0.0% 0.0% 0.0% 66.4% 2.7%

 Total 675,165 403,107 51,367 17,490 6,225 3,156 1,601 57,770 1,224,514

55.1% 32.9% 4.2% 1.4% 0.5% 0.3% 0.1% 4.7% 100.0%
Occupant Injury Data

National Automotive Sampling System/Crashworthiness Data System 1994-1996 27

0%

20%

40%

60%

80%

100%

Crash-Involved Car Occupants

Not Injured Minor Moderate Serious Severe Critical Maximum

No Treatment

Treated and Released

Transported and Released

Hospitalized

Fatality

Outcome

Maximum AIS Rating

(0) (1) (2) (3) (4) (5) (6)

The annual incidence of crash-involved car occupants as a function of maximum

injury severity and injury outcome is shown in Figure 7. This figure illustrates how injury

outcome progresses from “No Treatment” to “Fatality,” as the maximum injury

severity increases from “None” to “Untreatable” (Fatal). Similar comments apply for

light truck occupants, as shown in Table 14.

Figure 7

Annual Incidence of Injured Crash-Involved Car Occupants,

by Maximum Injury Severity and Treatment, 1994-1996
Occupant Injury Data

28 National Automotive Sampling System/Crashworthiness Data System 1994-1996

Effect of Alcohol Use on Injury Risk

The presence of alcohol in a motor vehicle driver increases (a) the likelihood of

being involved in a crash, (b) the severity of the crash, and possibly the severity of

the outcome in terms of survivability. In this report, alcohol reporting is based on the

police officer's assessment at the time of the crash.

Table 15 shows that, for drivers of passenger cars, those whose age is between 25

and 34 have the highest alcohol use rate, followed by the 35 through 44 age range

and then the 21- through 24-year-old drivers. Table 16 shows that, for drivers of light

trucks, those whose age is between 25 and 34 have the highest alcohol use rate,

followed by drivers 15 through 20 years old and then by those 35 through 44 years

old. Drivers of light trucks have almost twice the alcohol use rate of passenger car

drivers. These percentages are based on the “Total Known.”

Table 17 shows that, for drivers of passenger cars, as the severity of the injury

increases so does the presence of alcohol. Drivers in towed passenger cars with

alcohol present had MAIS 3-6 injury rates alsmost 3 times those for drivers with no

alcohol present. Approximately 24 percent of the MAIS 6 injuries are the result of

alcohol involvement, followed by 23 percent of the MAIS 5 injuries and 18 percent of

the MAIS 4 injuries. Table 18 describes the same pattern for drivers of towed light

trucks. Drivers in towed light trucks with alcohol present had MAIS 3-6 injury rates at

least twice those for drivers with no alcohol present.
Occupant Injury Data

National Automotive Sampling System/Crashworthiness Data System 1994-1996 29

Table 15

Distribution of Crash-Involved Car Drivers

by Age Group and Alcohol Use: Average per Year, 1994-1996

Police-Reported Alcohol

Use

Age Group (Years)

15-20 21-24 25-34 35-44 45-64 65 Unknown Total

No Alcohol Present 447,146 280,812 480,055 363,468 354,019 205,835 11,205 2,142,538

20.9% 13.1% 22.4% 17.0% 16.5% 9.6% 0.5% 84.6%

Alcohol Present 27,404 27,984 64,193 36,986 19,355 4,851 4,130 184,903

14.8% 15.1% 34.7% 20.0% 10.5% 2.6% 2.2% 7.3%

Not Reported 42,743 15,643 26,115 20,563 21,752 16,171 15,355 158,342

27.0% 9.9% 16.5% 13.0% 13.7% 10.2% 9.7% 6.3%

Not Coded 5,997 12,095 7,870 3,878 3,617 799 12,929 47,186

12.7% 25.6% 16.7% 8.2% 7.7% 1.7% 27.4% 1.9%

 Total 523,290 336,533 578,233 424,894 398,743 227,657 43,619 2,532,969

20.7% 13.3% 22.8% 16.8% 15.7% 9.0% 1.7% 100.0%

For each police-reported alcohol category, the first data row shows the number of drivers and the second row shows the

percentage of the row total.

Not Reported: Variable is not available on the police crash report.

Not Coded: Police Office did not provide the information.

Table 16

Distribution of Crash-Involved Light Truck Drivers

by Age Group and Alcohol Use: Average per Year, 1994-1996

Police-Reported Alcohol

Use

Age Group (Years)

15-20 21-24 25-34 35-44 45-64 65 Unknown Total

No Alcohol Present 121,117 60,306 161,778 140,285 127,989 26,800 1,582 639,857

18.9% 9.4% 25.3% 21.9% 20.0% 4.2% 0.2% 82.1%

Alcohol Present 17,463 13,892 21,421 15,834 15,329 760 1,768 86,466

20.2% 16.1% 24.8% 18.3% 17.7% 0.9% 2.0% 11.1%

Not Reported 5,183 2,079 14,553 4,950 5,309 718 1,652 34,442

15.0% 6.0% 42.3% 14.4% 15.4% 2.1% 4.8% 4.4%

Not Coded 3,016 1,748 1,848 2,314 1,669 1,783 6,308 18,685

16.1% 9.4% 9.9% 12.4% 8.9% 9.5% 33.8% 2.4%

 Total 146,778 78,024 199,599 163,382 150,295 30,062 11,310 779,450

18.8% 10.0% 25.6% 21.0% 19.3% 3.9% 1.5% 100.0%

For each police-reported alcohol category, the first data row shows the number of drivers and the second row shows the

percentage of the row total.

Not Reported: Variable is not available on the police crash report.

Not Coded: Police Office did not provide the information.
Occupant Injury Data

30 National Automotive Sampling System/Crashworthiness Data System 1994-1996

Table 17

Distribution of Crash-Involved Car Drivers by Alcohol Use

and Maximum Injury Severity: Average per Year, 1994-1996

Police-Reported

Alcohol Use

Frequency of Injury by Maximum AIS Rating*

Not Injured

(0)

Minor

(1)

Moderate

(2)

Serious

(3)

Severe

(4)

Critical

(5)

Maximum

(6)

Injured,

Severity

Unknown (7) Total

No Alcohol

Present

1,017,247 862,458 90,720 35,973 5,252 3,603 805 121,243 2,142,538

47.5% 40.3% 4.2% 1.7% 0.2% 0.2% 0.0% 5.7% 84.6%

Alcohol Present 69,748 78,238 13,002 5,983 1,765 1,556 487 11,807 184,903

37.7% 42.3% 7.0% 3.2% 1.0% 0.8% 0.3% 6.4% 7.3%

Not Reported 64,537 65,731 6,397 1,917 692 561 528 6,326 158,342

40.8% 41.5% 4.0% 1.2% 0.4% 0.4% 0.3% 4.0% 6.3%

Not Coded 22,310 10,273 1,637 2,082 1,903 1,082 180 1,550 47,186

47.3% 21.8% 3.5% 4.4% 4.0% 2.3% 0.4% 3.3% 1.9%

 Total 1,173,842 1,016,701 111,756 45,954 9,612 6,802 2,000 140,925 2,532,969

46.3% 40.1% 4.4% 1.8% 0.4% 0.3% 0.1% 5.6% 100.0%

For each police-reported alcohol use category, the first data row shows the number of drivers involved and the second row shows the

percentage of the row total. The row totals include the number of “unknown if injured.”

Not Reported: Variable is not available on the police crash report.

Not Coded: Police Office did not provide the information.
Occupant Injury Data

National Automotive Sampling System/Crashworthiness Data System 1994-1996 31

Table 18

Distribution of Crash-Involved Light Truck Drivers by Alcohol Use

and Maximum Injury Severity: Average per Year, 1994-1996

Police-Reported

Alcohol Use

Frequency of Injury by Maximum AIS Rating*

Not Injured

(0)

Minor

(1)

Moderate

(2)

Serious

(3)

Severe

(4)

Critical

(5)

Maximum

(6)

Injured,

Severity

Unknown (7) Total

No Alcohol

Present

330,223 239,746 21,865 8,342 2,355 1,225 372 35,281 639,857

51.6% 37.5% 3.4% 1.3% 0.4% 0.2% 0.1% 5.5% 82.1%

Alcohol Present 32,964 40,353 5,033 1,771 1,165 471 147 2,782 86,466

38.1% 46.7% 5.8% 2.0% 1.3% 0.5% 0.2% 3.2% 11.1%

Not Reported 19,772 5,328 6,136 336 112 115 111 2,416 34,442

57.4% 15.5% 17.8% 1.0% 0.3% 0.3% 0.3% 7.0% 4.4%

Not Coded 4,489 3,079 1,860 1,045 781 233 819 992 18,685

24.0% 16.5% 10.0% 5.6% 4.2% 1.2% 4.4% 5.3% 2.4%

 Total 387,447 288,506 34,894 11,495 4,413 2,044 1,450 41,470 779,450

49.7% 37.0% 4.5% 1.5% 0.6% 0.3% 0.2% 5.3% 100.0%

For each police-reported alcohol use category, the first data row shows the number of drivers involved and the second row shows the

percentage of the row total. The row totals include the number of “unknown if injured.”

Not Reported: Variable is not available on the police crash report.

Not Coded: Police Office did not provide the information.
Occupant Injury Data

32 National Automotive Sampling System/Crashworthiness Data System 1994-1996

Table 19

Distribution of All Injuries to Crash-Involved Car Occupants

by Body Region and Severity: Average per Year, 1994-1996

Body Region

Frequency of Injury by AIS Rating*

1 2 3 4 5 6 7 Total

Head (Brain) 39,344 62,493 22,228 11,435 8,751 747 0 144,998

27.1% 43.1% 15.3% 7.9% 6.0% 0.5% 0.0%

0.9% 19.6% 16.6% 36.9% 57.2% 20.2% 0.0%

Head (Skull) 0 3,534 5,511 2,171 0 443 0 11,658

 0.0% 30.3% 47.3% 18.6% 0.0% 3.8% 0.0%

 0.0% 1.1% 4.1% 7.0% 0.0% 12.0% 0.0%

Head (Other) 0 442 21 47 38 0 8,117 8,666

0.0% 5.1% 0.2% 0.5% 0.4% 0.0% 93.7%

0.0% 0.1% 0.0% 0.2% 0.2% 0.0% 31.4%

Face 74,232 17,465 4,810 107 0 0 42 96,654

76.8% 18.1% 5.0% 0.1% 0.0% 0.0% 0.0%

1.7% 5.5% 3.6% 0.3% 0.0% 0.0% 0.2%

Neck 371,631 236 35 22 0 10 2,240 374,174

99.3% 0.1% 0.0% 0.0% 0.0% 0.0% 0.6%

8.6% 0.1% 0.0% 0.1% 0.0% 0.3% 8.7%

Chest 28,607 24,818 34,755 10,673 4,087 1,876 8,812 113,628

25.2% 21.8% 30.6% 9.4% 3.6% 1.7% 7.8%

0.7% 7.8% 26.0% 34.4% 26.7% 50.7% 34.1%

Shoulder and Back 196,256 49,404 4,222 90 0 0 1,423 251,395

78.1% 19.7% 1.7% 0.0% 0.0% 0.0% 0.6%

4.5% 15.5% 3.2% 0.3% 0.0% 0.0% 5.5%

*For each body region, the first data row shows the number of injuries, the second row shows the percentage of the row total, and

the third row shows the percentage of the column total.

Body Regions Injured in Traffic Crashes

There are about 2,544,000 cars towed away from traffic crashes every year. The

incidence of crash-involved occupants in these cars is about 3,800,000 per year. Of

these, about 1,934,000 car occupants per year are injured, incurring about 4,844,000

injuries of various severities, in various body regions, and by various injury contacts.

Table 19 shows the distribution of all injuries incurred by injured occupants of crashinvolved cars (as opposed to each occupant's most severe injury, reported in Tables

9-18) as a function of injury severity and injured body region. Table 20 shows the

same distribution for injured occupants of light trucks.

The numbers for “injured, severity unknown” (AIS=7) are lower in these tables than in

tables using maximum AIS (MAIS), because of the level of information available for

coding the injuries. An AIS of 7 is assigned to an injury when there is not sufficient

information about the injury available. An MAIS of 7 is assigned to an occupant

when it is known that the occupant was injured, but no information about the injury is

available. Therefore, an occupant with an MAIS of 7 may not have any associated

injuries coded.
Occupant Injury Data

National Automotive Sampling System/Crashworthiness Data System 1994-1996 33

Table 19 (Continued)

Distribution of All Injuries to Crash-Involved Car Occupants

by Body Region and Severity: Average per Year, 1994-1996

Body Region

Frequency of Injury by AIS Rating*

1 2 3 4 5 6 7 Total

Abdomen 809 20,263 4,557 5,052 1,326 4 4,421 36,432

2.2% 55.6% 12.5% 13.9% 3.6% 0.0% 12.1%

0.0% 6.4% 3.4% 16.3% 8.7% 0.1% 17.1%

Spine 0 0 467 1,372 732 192 0 2,763

0.0% 0.0% 16.9% 49.7% 26.5% 6.9% 0.0%

0.0% 0.0% 0.3% 4.4% 4.8% 5.2% 0.0%

Upper Extremities 61,518 35,663 23,057 0 0 0 651 120,889

50.9% 29.5% 19.1% 0.0% 0.0% 0.0% 0.5%

1.4% 11.2% 17.3% 0.0% 0.0% 0.0% 2.5%

Pelvis 0 16,954 8,377 23 36 0 0 25,390

0.0% 66.8% 33.0% 0.1% 0.1% 0.0% 0.0%

0.0% 5.3% 6.3% 0.1% 0.2% 0.0% 0.0%

Lower Extremities 42,337 83,608 25,231 6 0 0 132 151,313

28.0% 55.3% 16.7% 0.0% 0.0% 0.0% 0.1%

1.0% 26.2% 18.9% 0.0% 0.0% 0.0% 0.5%

Skin 3,500,721 3,793 241 0 7 430 0 3,505,192

99.9% 0.1% 0.0% 0.0% 0.0% 0.0% 0.0%

81.1% 1.2% 0.2% 0.0% 0.0% 11.6% 0.0%

All Other 11 16 129 33 315 0 0 503

2.2% 3.2% 25.6% 6.6% 62.6% 0.0% 0.0%

0.0% 0.0% 0.1% 0.1% 2.1% 0.0% 0.0%

 Total 4,315,465 318,690 133,639 31,030 15,293 3,702 25,837 4,843,655

*For each body region, the first data row shows the number of injuries, the second row shows the percentage of the row total, and

the third row shows the percentage of the column total.
Occupant Injury Data

34 National Automotive Sampling System/Crashworthiness Data System 1994-1996

Table 20

Distribution of All Injuries to Crash-Involved Light Truck Occupants

by Body Region and Severity: Average per Year, 1994-1996

Body Region

Frequency of Injury by AIS Rating*

1 2 3 4 5 6 7 Total

Head (Brain) 16,450 26,768 8,485 5,145 3,068 235 0 60,150

27.3% 44.5% 14.1% 8.6% 5.1% 0.4% 0.0%

1.2% 21.8% 19.1% 40.1% 62.7% 12.6% 0.0%

Head (Skull) 0 2,157 3,052 1,401 0 512 0 7,122

 0.0% 30.3% 42.9% 19.7% 0.0% 7.2% 0.0%

 0.0% 1.8% 6.9% 10.9% 0.0% 27.4% 0.0%

Head (Other) 0 12 0 85 0 0 6,811 6,908

0.0% 0.2% 0.0% 1.2% 0.0% 0.0% 98.6%

0.0% 0.0% 0.0% 0.7% 0.0% 0.0% 58.0%

Face 22,810 10,325 1,843 0 0 0 17 34,995

65.2% 29.5% 5.3% 0.0% 0.0% 0.0% 0.0%

1.7% 8.4% 4.1% 0.0% 0.0% 0.0% 0.1%

Neck 89,616 116 13 0 0 6 0 89,750

99.9% 0.1% 0.0% 0.0% 0.0% 0.0% 0.0%

6.5% 0.1% 0.0% 0.0% 0.0% 0.3% 0.0%

Chest 5,938 7,354 8,689 4,352 1,041 542 1,608 29,523

20.1% 24.9% 29.4% 14.7% 3.5% 1.8% 5.4%

0.4% 6.0% 19.6% 33.9% 21.3% 29.0% 13.7%

Shoulder and Back 46,265 20,447 2,748 0 0 0 0 69,460

66.6% 29.4% 4.0% 0.0% 0.0% 0.0% 0.0%

3.4% 16.6% 6.2% 0.0% 0.0% 0.0% 0.0%

*For each body region, the first data row shows the number of injuries, the second row shows the percentage of the row total, and

the third row shows the percentage of the column total.
Occupant Injury Data

National Automotive Sampling System/Crashworthiness Data System 1994-1996 35

Table 20 (Continued)

Distribution of All Injuries to Crash-Involved Light Truck Occupants

by Body Region and Severity: Average per Year, 1994-1996

Body Region

Frequency of Injury by AIS Rating*

1 2 3 4 5 6 7 Total

Abdomen 623 6,640 985 1,453 423 0 3,207 13,330

4.7% 49.8% 7.4% 10.9% 3.2% 0.0% 24.1%

0.0% 5.4% 2.2% 11.3% 8.6% 0.0% 27.3%

Spine 0 0 150 406 200 34 0 789

0.0% 0.0% 19.0% 51.5% 25.3% 4.3% 0.0%

0.0% 0.0% 0.3% 3.2% 4.1% 1.8% 0.0%

Upper Extremities 18,569 14,595 5,209 0 0 0 19 38,391

48.4% 38.0% 13.6% 0.0% 0.0% 0.0% 0.0%

1.4% 11.9% 11.7% 0.0% 0.0% 0.0% 0.2%

Pelvis 0 5,258 4,798 4 89 0 0 10,150

0.0% 51.8% 47.3% 0.0% 0.9% 0.0% 0.0%

0.0% 4.3% 10.8% 0.0% 1.8% 0.0% 0.0%

Lower Extremities 10,598 26,232 8,193 0 0 0 75 45,097

23.5% 58.2% 18.2% 0.0% 0.0% 0.0% 0.2%

0.8% 21.3% 18.4% 0.0% 0.0% 0.0% 0.6%

Skin 1,164,148 3,025 215 0 72 542 0 1,168,002

99.7% 0.3% 0.0% 0.0% 0.0% 0.0% 0.0%

84.7% 2.5% 0.5% 0.0% 1.5% 29.0% 0.0%

All Other 0 17 33 0 1 0 0 51

0.0% 33.3% 64.7% 0.0% 2.0% 0.0% 0.0%

0.0% 0.0% 0.1% 0.0% 0.0% 0.0% 0.0%

 Total 1,375,016 122,945 44,411 12,845 4,894 1,870 11,737 1,573,718

*For each body region, the first data row shows the number of injuries, the second row shows the percentage of the row total, and

the third row shows the percentage of the column total.
Occupant Injury Data

36 National Automotive Sampling System/Crashworthiness Data System 1994-1996

0% 20% 40% 60% 80%

Car Occupant Injuries

All Other

Skin

Lower Extremities

Pelvis

Upper Extremities

Spine

Abdomen

Shoulder and Back

Chest

Neck

Face

Head (Other)

Head (Skull)

Head (Brain)

Body Region Injured

Serious-Maximum

All Severities

It is apparent from Tables 19 and 20 that the body regions most frequently affected

by injuries of all severities are markedly different from those most frequently affected

by injuries of high severities (serious-maximum (AIS=3-6)). This is illustrated in Figure 8,

where two distributions are shown: one for all severities and one for serious-maximum

severities, each adding up to 100 percent.

It is evident in this figure that body regions such as face, neck, shoulder and back,

and skin are injured with a high frequency in general, but occur at very low

frequencies for serious to maximum severities. Conversely, other body regions, such

as the head (brain/skull), chest, spine, abdomen, and upper and lower extremities

are injured frequently at high severities, but occur less significantly when all severities

are considered.

Figure 8

Distribution of Injuries to Crash-Involved Car Occupants

by Affected Body Region and Severity of Inury, 1994-1996
Occupant Injury Data

National Automotive Sampling System/Crashworthiness Data System 1994-1996 37

Belt Use and Body Regions Injured

Figure 9 shows the distribution of crash-involved car occupants by injured body

region and belt usage. An occupant may receive more than one injury to a given

body region; however, this figure represents one injury per body region per

occupant. An occupant may also receive injuries across more than one body

region. Therefore, the number for each body region will add up to more than the

number of injured occupants. For example, an occupant may have a contusion to

the left side of the brain and a laceration to the right side of the brain. The figure

counts only one of the injuries to the brain. If the occupant in the example sustained

a contusion to the left side of the brain and a skull fracture, then both injuries would

be included in the figure, and one injury would be counted in the brain body region

while the other injury would be counted in the skull body region. To determine the

percent of belted occupants who sustained a brain injury, divide the number of

occupants with a brain injury by the total number of occupants using a restraint

system. The same methodology applies to the unbelted occupants. The

percentages will not add to 100 percent, because the total number of occupants

includes those who were not injured. Figure 10 shows a similar distribution of crashinvolved occupants of light trucks by belt usage.
Occupant Injury Data

38 National Automotive Sampling System/Crashworthiness Data System 1994-1996

Figure 9

Distribution of Injuries by Body Region to Crash-Involved

Car Occupants by Belt Usage: Average per Year, 1994-1996

Belted Unbelted

Brain: 48,896 (2.0%) Brain: 59,240 (7.5%)

Other Head: 2,802 (0.1%) Other Head: 4,281 (0.5%)

Face: 29,064 (1.2%) Face: 37,269 (4.7%)

Chest: 57,691 (2.3%) Chest: 26,997 (3.4%)

Upper Upper

Extremities: 60,022 (2.4%) Extremities: 36,144 (4.6%)

Abdomen: 10,067 (0.4%)

Abdomen: 10,945 (1.4%)

Skin: 927,202 (37.7%) Skin: 437,628 (55.4%)

Skull: 6,679 (0.1%) Skull: 4,548 (0.6%)

Neck: 288,263 (11.7%) Neck: 63,788 (8.1%)

Shoulder Shoulder

and Back: 158,553 (6.4%) and Back: 52,224 (6.6%)

Spine: 509 (0.0%) Spine: 1,196 (0.2%)

Pelvis: 5,368 (2.2%) Pelvis: 11,454 (1.5%)

Lower Lower

Extremities: 63,210 (2.6%) Extremities: 36,435 (4.6%)

Total Total

Belted Unbelted

Occupants: Occupants:

2,460,430 789,094
Occupant Injury Data

40 National Automotive Sampling System/Crashworthiness Data System 1994-1996

Figure 10

Distribution of Injuries by Body Region to Crash-Involved

Light Truck Occupants by Belt Usage: Average per Year, 1994-1996

Belted Unbelted

Brain: 17,868 (2.4%) Brain: 29,936 (9.7%)

Other Head: 728 (0.1%)

Other Head: 6,015 (2.0%)

Face: 5,689 (0.8%) Face: 16,690 (5.4%)

Chest: 8,941 (1.2%) Chest: 12,294 (4.0%)

Upper Upper

Extremities: 19,615 (2.6%) Extremities: 8,752 (2.8%)

Abdomen: 2,040 (0.3%)

Abdomen: 6,432 (2.1%)

Skin: 248,173 (33.3%) Skin: 164,253 (53.4%)

Skull: 700 (0.1%) Skull: 3,828 (1.2%)

Neck: 64,413 (8.7%) Neck: 20,190 (6.6%)

Shoulder Shoulder

and Back: 27,922 (3.8%)

and Back: 25,248 (8.2%)

Spine: 195 (0.0%) Spine: 445 (0.1%)

Pelvis: 1,952 (0.3%) Pelvis: 4,391 (1.4%)

Lower Lower

Extremities: 10,734 (1.4%) Extremities: 15,161 (4.9%)

Total Total

Belted Unbelted

Occupants: Occupants:

744,397 307,417
Occupant Injury Data

42 National Automotive Sampling System/Crashworthiness Data System 1994-1996

Injury Contacts

In addition to data on injured body regions, crash protection practitioners need data

concerning the various sources of injury (injury contacts). A summary of injury contacts

for injuries to crash-involved occupants is presented in Table 21 for cars and in Table

22 for light trucks. Table 21 shows the distribution of all crash-involved car occupant

injuries as a function of injury severity and injury contact. Table 22 shows the same

distribution for light truck occupants.
Occupant Injury Data

National Automotive Sampling System/Crashworthiness Data System 1994-1996 43

Table 21

Distribution of All Injuries to Crash-Involved Car Occupants

by Injury Contact and Severity: Average per Year, 1994-1996

Injury Contact

Frequency of Injury by AIS Rating*

1 2 3 4 5 6 7 Total

Steering Assembly 437,476 43,401 21,568 4,360 1,919 653 3,958 513,335

85.2% 8.5% 4.2% 0.8% 0.4% 0.1% 0.8%

10.1% 13.6% 16.1% 14.1% 12.5% 17.6% 15.3%

Instrument Panel 643,057 49,049 18,888 1,124 655 415 744 713,931

90.1% 6.9% 2.6% 0.2% 0.1% 0.1% 0.1%

14.9% 15.4% 14.1% 3.6% 4.3% 11.2% 2.9%

Windshield 382,120 20,083 7,749 2,187 1,065 69 2,051 415,326

92.0% 4.8% 1.9% 0.5% 0.3% 0.0% 0.5%

8.9% 6.3% 5.8% 7.0% 7.0% 1.9% 7.9%

Interior Side Surface 324,229 35,832 21,260 5,237 2,231 316 989 390,094

83.1% 9.2% 5.4% 1.3% 0.6% 0.1% 0.3%

7.5% 11.2% 15.9% 16.9% 14.6% 8.5% 3.8%

Pillars 86,342 12,091 5,495 2,297 1,500 156 364 108,244

79.8% 11.2% 5.1% 2.1% 1.4% 0.1% 0.3%

2.0% 3.8% 4.1% 7.4% 9.8% 4.2% 1.4%

Restraint (Belt) System 500,003 15,462 8,237 1,655 344 14 3,011 528,727

94.6% 2.9% 1.6% 0.3% 0.1% 0.0% 0.6%

11.6% 4.9% 6.2% 5.3% 2.2% 0.4% 11.7%

Child Seat 6,287 656 44 9 35 14 14 7,059

89.1% 9.3% 0.6% 0.1% 0.5% 0.2% 0.2%

0.1% 0.2% 0.0% 0.0% 0.2% 0.4% 0.1%

Air Bag 256,490 2,305 1,122 319 393 38 146 260,813

98.3% 0.9% 0.4% 0.1% 0.2% 0.0% 0.1%

5.9% 0.7% 0.8% 1.0% 2.6% 1.0% 0.6%

Head Restraints 40,841 4,988 485 185 35 0 89 46,623

87.6% 10.7% 1.0% 0.4% 0.1% 0.0% 0.2%

0.9% 1.6% 0.4% 0.6% 0.2% 0.0% 0.3%

Seat Back 175,756 12,920 6,903 568 111 17 88 196,364

89.5% 6.6% 3.5% 0.3% 0.1% 0.0% 0.0%

4.1% 4.1% 5.2% 1.8% 0.7% 0.5% 0.3%

Roof 86,276 14,250 6,426 2,997 1,905 202 1,026 113,082

76.3% 12.6% 5.7% 2.7% 1.7% 0.2% 0.9%

2.0% 4.5% 4.8% 9.7% 12.5% 5.5% 4.0%

*For each injury contact, the first data row shows the number of injuries, the second row shows the percentage of the row total,

and the third row shows the percentage of the column total.
Occupant Injury Data

44 National Automotive Sampling System/Crashworthiness Data System 1994-1996

Table 21 (Continued)

Distribution of All Injuries to Crash-Involved Car Occupants

by Injury Contact and Severity: Average per Year, 1994-1996

Injury Contact

Frequency of Injury by AIS Rating*

1 2 3 4 5 6 7 Total

Floor 69,179 32,556 3,214 0 0 0 0 104,950

65.9% 31.0% 3.1% 0.0% 0.0% 0.0% 0.0%

1.6% 10.2% 2.4% 0.0% 0.0% 0.0% 0.0%

Non-Contact Injuries 573,404 4,387 601 142 479 32 803 579,847

98.9% 0.8% 0.1% 0.0% 0.1% 0.0% 0.1%

13.3% 1.4% 0.4% 0.5% 3.1% 0.9% 3.1%

Fire in Vehicle 420 17 242 7 7 430 0 1,123

37.4% 1.5% 21.5% 0.6% 0.6% 38.3% 0.0%

0.0% 0.0% 0.2% 0.0% 0.0% 11.6% 0.0%

Ground 33,537 5,848 2,880 1,366 458 148 284 44,523

75.3% 13.1% 6.5% 3.1% 1.0% 0.3% 0.6%

0.8% 1.8% 2.2% 4.4% 3.0% 4.0% 1.1%

Exterior (Occupant's

Vehicle)

3,811 2,185 1,278 725 436 208 194 8,838

43.1% 24.7% 14.5% 8.2% 4.9% 2.4% 2.2%

0.1% 0.7% 1.0% 2.3% 2.9% 5.6% 0.8%

Exterior (Other Vehicle

or Exterior Object)

6,647 2,740 2,057 1,305 755 354 145 14,003

47.5% 19.6% 14.7% 9.3% 5.4% 2.5% 1.0%

0.2% 0.9% 1.5% 4.2% 4.9% 9.6% 0.6%

Side and Rear Glazing 65,777 6,048 864 217 164 15 95 73,179

89.9% 8.3% 1.2% 0.3% 0.2% 0.0% 0.1%

1.5% 1.9% 0.6% 0.7% 1.1% 0.4% 0.4%

All Others 221,486 15,449 6,898 939 236 16 704 245,728

90.1% 6.3% 2.8% 0.4% 0.1% 0.0% 0.3%

5.1% 4.8% 5.2% 3.0% 1.5% 0.4% 2.7%

Unknown 402,328 38,422 17,427 5,392 2,565 602 11,132 477,868

84.2% 8.0% 3.6% 1.1% 0.5% 0.1% 2.3%

9.3% 12.1% 13.0% 17.4% 16.8% 16.3% 43.1%

Total 4,315,465 318,690 133,639 31,030 15,293 3,702 25,837 4,843,655

*For each injury contact, the first data row shows the number of injuries, the second row shows the percentage of the row total,

and the third row shows the percentage of the column total.
Occupant Injury Data

National Automotive Sampling System/Crashworthiness Data System 1994-1996 45

Table 22

Distribution of All Injuries to Crash-Involved Light Truck Occupants

by Injury Contact and Severity: Average per Year, 1994-1996

Injury Contact

Frequency of Injury by AIS Rating*

1 2 3 4 5 6 7 Total

Steering Assembly 140,269 14,345 5,124 2,124 612 172 4,263 166,908

84.0% 8.6% 3.1% 1.3% 0.4% 0.1% 2.6%

10.2% 11.7% 11.5% 16.5% 12.5% 9.2% 36.3%

Instrument Panel 213,041 21,541 7,723 350 177 28 124 242,983

87.7% 8.9% 3.2% 0.1% 0.1% 0.0% 0.1%

15.5% 17.5% 17.4% 2.7% 3.6% 1.5% 1.1%

Windshield 115,717 5,810 905 410 235 219 3,975 127,271

90.9% 4.6% 0.7% 0.3% 0.2% 0.2% 3.1%

8.4% 4.7% 2.0% 3.2% 4.8% 11.7% 33.9%

Interior Side Surface 99,319 9,230 6,784 1,180 307 113 120 117,055

84.8% 7.9% 5.8% 1.0% 0.3% 0.1% 0.1%

7.2% 7.5% 15.3% 9.2% 6.3% 6.0% 1.0%

Pillars 39,192 8,398 1,797 953 323 0 200 50,863

77.1% 16.5% 3.5% 1.9% 0.6% 0.0% 0.4%

2.9% 6.8% 4.0% 7.4% 6.6% 0.0% 1.7%

Restraint (Belt) System 133,932 2,498 1,225 252 0 0 326 138,233

96.9% 1.8% 0.9% 0.2% 0.0% 0.0% 0.2%

9.7% 2.0% 2.8% 2.0% 0.0% 0.0% 2.8%

Child Seat 3,383 290 82 0 0 0 5 3,760

90.0% 7.7% 2.2% 0.0% 0.0% 0.0% 0.1%

0.2% 0.2% 0.2% 0.0% 0.0% 0.0% 0.0%

Air Bag 25,636 1,542 161 0 0 3 2 27,345

93.8% 5.6% 0.6% 0.0% 0.0% 0.0% 0.0%

1.9% 1.3% 0.4% 0.0% 0.0% 0.2% 0.0%

Head Restraints 13,059 1,395 4 0 0 0 21 14,479

90.2% 9.6% 0.0% 0.0% 0.0% 0.0% 0.1%

0.9% 1.1% 0.0% 0.0% 0.0% 0.0% 0.2%

Seat Back 40,555 4,840 451 204 71 0 16 46,137

87.9% 10.5% 1.0% 0.4% 0.2% 0.0% 0.0%

2.9% 3.9% 1.0% 1.6% 1.5% 0.0% 0.1%

Roof 53,157 9,292 3,134 986 647 173 374 67,763

78.4% 13.7% 4.6% 1.5% 1.0% 0.3% 0.6%

3.9% 7.6% 7.1% 7.7% 13.2% 9.3% 3.2%

*For each injury contact, the first data row shows the number of injuries, the second row shows the percentage of the row total,

and the third row shows the percentage of the column total.
Occupant Injury Data

46 National Automotive Sampling System/Crashworthiness Data System 1994-1996

Table 22 (Continued)

Distribution of All Injuries to Crash-Involved Light Truck Occupants

by Injury Contact and Severity: Average per Year, 1994-1996

Injury Contact

Frequency of Injury by AIS Rating*

1 2 3 4 5 6 7 Total

Floor 17,642 9,014 613 0 0 0 0 27,268

64.7% 33.1% 2.2% 0.0% 0.0% 0.0% 0.0%

1.3% 7.3% 1.4% 0.0% 0.0% 0.0% 0.0%

Non-Contact Injuries 163,317 755 315 18 182 26 14 164,627

99.2% 0.5% 0.2% 0.0% 0.1% 0.0% 0.0%

11.9% 0.6% 0.7% 0.1% 3.7% 1.4% 0.1%

Fire in Vehicle 29 0 67 0 70 542 0 708

4.1% 0.0% 9.5% 0.0% 9.9% 76.6% 0.0%

0.0% 0.0% 0.2% 0.0% 1.4% 29.0% 0.0%

Ground 44,973 12,231 5,416 2,051 963 59 616 66,309

67.8% 18.4% 8.2% 3.1% 1.5% 0.1% 0.9%

3.3% 9.9% 12.2% 16.0% 19.7% 3.2% 5.2%

Exterior (Occupant's

Vehicle)

5,446 4,046 2,057 907 238 64 55 12,814

42.5% 31.6% 16.1% 7.1% 1.9% 0.5% 0.4%

0.4% 3.3% 4.6% 7.1% 4.9% 3.4% 0.5%

Exterior (Other Vehicle

or Exterior Object)

2,206 1,430 1,531 662 256 157 138 6,380

34.6% 22.4% 24.0% 10.4% 4.0% 2.5% 2.2%

0.2% 1.2% 3.4% 5.2% 5.2% 8.4% 1.2%

Side and Rear Glazing 27,617 1,538 744 22 12 0 23 29,956

92.2% 5.1% 2.5% 0.1% 0.0% 0.0% 0.1%

2.0% 1.3% 1.7% 0.2% 0.2% 0.0% 0.2%

All Others 86,759 3,781 815 216 74 0 54 91,699

94.6% 4.1% 0.9% 0.2% 0.1% 0.0% 0.1%

6.3% 3.1% 1.8% 1.7% 1.5% 0.0% 0.5%

Unknown 149,766 10,969 5,466 2,509 726 313 1,410 171,160

87.5% 6.4% 3.2% 1.5% 0.4% 0.2% 0.8%

10.9% 8.9% 12.3% 19.5% 14.8% 16.7% 12.0%

Total 1,375,016 122,945 44,411 12,845 4,894 1,870 11,737 1,573,718

*For each injury contact, the first data row shows the number of injuries, the second row shows the percentage of the row total,

and the third row shows the percentage of the column total.
Occupant Injury Data

National Automotive Sampling System/Crashworthiness Data System 1994-1996 47

0% 5% 10% 15% 20%

Car Occupant Injuries

All Others

Head Restraints

Ground

Side/Rear Glazing

Pillars

Floor

Airbag

Seat Back

Roof

Interior Side

Restraint System

Non-Contact Injuries

Windshield

Steering Assembly

Instrument Panel

Injury Contact

All Severities

Serious-Maximum

It is evident from Tables 21 and 22 that the most frequent injury contacts for injuries of

all severities (AIS 1-7) are not necessarily the same as those that are most frequently

involved in serious to maximum injuries (AIS 3-6). This is illustrated in Figure 11, where

two distributions are shown: one for all severities and one for serious to maximum

severities, each adding up to 100 percent.

As can be seen in this figure, the instrument panel, windshield, and restraint system as

injury contacts have high frequencies in general but relatively low frequencies for

serious to maximum injuries. The converse is observed for the steering assembly,

interior side, roof, pillars, and ground.

Figure 11

Distribution of Injuries to Crash-Involved Car Occupants

by Injury Contact and Severity of Injury, 1994-1996

Note: All Others category includes items shown in Table 22 (child seat and exterior of occupant’s vehicle, other

vehicle, or exterior object). Unknowns are excluded from Figure 11.
Occupant Injury Data

48 National Automotive Sampling System/Crashworthiness Data System 1994-1996

Table 23

Occupant Ejection and Entrapment in Crash-Involved Towed Cars

by Degree of Ejection, Crash Mode, and Area of Damage:

Average of Nationally Weighted Counts per Year, 1994-1996

Crash Mode and

Area of Damage

Complete

Ejection

Partial

Ejection Entrapment Total

Rollover 8,519 4,437 895 169,975

5.0% 2.6% 0.5% 4.5%

Nonrollover

 Single-Vehicle

 Front 966 897 3,360 540,818

0.2% 0.2% 0.6% 14.2%

 Side 2,094 2,514 1,552 173,215

1.2% 1.5% 0.9% 4.6%

 Rear, Top, or Under 21 53 5 28,693

0.1% 0.2% 0.0% 0.8%

 Multiple-Vehicle

 Front 542 1,537 4,377 1,599,086

0.0% 0.1% 0.3% 42.1%

 Side 1,897 2,392 2,294 967,262

0.2% 0.2% 0.2% 25.5%

 Rear 343 353 30 315,810

0.1% 0.1% 0.0% 8.3%

 Top or Under 0 0 0 3245

0.0% 0.0% 0.0% 0.1%

Total 14,380 12,182 12,514 3,798,104

0.4% 0.3% 0.3% 100.0%

*For each crash mode, the first data row shows the number of occupants ejected or entrapped and the second row

shows the percentage of the row total.

Note: Damage Area “Unknown” has been imputed into the known damage areas.

Occupant Ejection and Entrapment

Table 23 shows the rates of occupant ejections from and entrapment in crashinvolved towed cars. Two degrees of ejection are distinguished: complete and

partial. The results in Table 23 are shown by primary crash modes and areas of

damage. Similar data for light trucks are shown in Table 24. Ejection rates by degree

of ejection are also shown in Figure 12. Ejection occurs most frequently in rollover

crashes, followed by side impacts.
Occupant Injury Data

National Automotive Sampling System/Crashworthiness Data System 1994-1996 49

Table 24

Occupant Ejection and Entrapment in Crash-Involved Towed Light Trucks

by Degree of Ejection, Crash Mode, and Area of Damage:

Average of Nationally Weighted Counts per Year, 1994-1996

Crash Mode and

Area of Damage

Complete

Ejection

Partial

Ejection Entrapment Total

Rollover 14,915 5,839 2,009 189,068

7.9% 3.1% 1.1% 15.4%

Nonrollover

 Single-Vehicle

 Front 648 853 851 210,853

0.3% 0.4% 0.4% 17.2%

 Side 303 426 284 33,274

0.9% 1.3% 0.9% 2.7%

 Rear, Top, or Under 3 0 13 9,774

0.0% 0.0% 0.1% 0.8%

 Multiple-Vehicle

 Front 1,239 403 1,492 548,477

0.2% 0.1% 0.3% 44.8%

 Side 3,483 231 378 182,021

1.9% 0.1% 0.2% 14.9%

 Rear 261 576 262 51,007

0.5% 1.1% 0.5% 4.2%

 Top or Under 0 0 11 41

0.0% 0.0% 26.8% 0.0%

Total 20,851 8,328 5,301 1,224,514

1.7% 0.7% 0.4% 100.0%

*For each crash mode, the first data row shows the number of occupants ejected or entrapped and the second row

shows the percentage of the row total.

Note: Damage Area “Unknown” has been imputed into the known damage areas.
Occupant Injury Data

50 National Automotive Sampling System/Crashworthiness Data System 1994-1996

0% 1% 2% 3% 4% 5%

Frequency

All Crash Modes

Rear

Side

Frontal

Side

Frontal

Rollover

Nonrollover

Single-Vehicle

Multiple-Vehicle

Complete

Ejection

Figure 12

Towed Car Occupant Ejection Rates

by Crash Mode and Degree of Ejection, 1994-1996
Occupant Injury Data

National Automotive Sampling System/Crashworthiness Data System 1994-1996 51

Table 25

Injury-Weighted Occupant Ejection and Entrapment Rates

for Crash-Involved Towed Cars

by Degree of Ejection, Crash Mode, and Area of Damage:

Average of Nationally Weighted Counts per Year, 1994-1996

Crash Mode and

Area of Damage

Complete

Ejection

Partial

Ejection Entrapment Total

Rollover 1,530,211 692,621 240,247 5,447,957

28.1% 12.7% 4.4% 13.3%

Nonrollover

 Single-Vehicle

 Front 231,088 205,417 528,442 6,385,927

3.6% 3.2% 8.3% 15.6%

 Side 310,520 277,245 388,920 2,681,532

11.6% 10.3% 14.5% 6.6%

 Rear, Top, or Under 96 20,599 102 268,703

0.0% 7.7% 0.0% 0.7%

 Multiple-Vehicle

 Front 195,819 262,602 1,217,441 13,985,807

1.4% 1.9% 8.7% 34.2%

 Side 392,455 601,447 652,889 10,342,682

3.8% 5.8% 6.3% 25.3%

 Rear 21,819 23,131 10,682 1,787,654

1.2% 1.3% 0.6% 4.4%

 Top or Under 0 0 0 15798

0.0% 0.0% 0.0% 0.0%

Total 2,682,008 2,083,062 3,038,723 40,916,061

6.6% 5.1% 7.4% 100.0%

*For each crash mode, the first data row shows the number of occupants ejected or entrapped and the second row

shows the percentage of the row total.

The ejection rates shown in Tables 23 and 24 are generally small, except in rollovers.

However, due to the very harmful outcomes of occupant ejections, the rate of injuries

associated with occupant ejections is significantly higher, as shown in Tables 25 and

26, which show injury-weighted (using Harm—see Appendix E) ejection and

entrapment data for crash-involved towed vehicles, and Figure 13, which shows

ejection-induced injury rates for towed vehicles. Crashes that involve ejection are

generally more severe crashes; therefore, injuries to ejected occupants may be due

to higher crash forces as well as the ejection itself.
Occupant Injury Data

52 National Automotive Sampling System/Crashworthiness Data System 1994-1996

Table 26

Injury-Weighted Occupant Ejection and Entrapment Rates

for Crash-Involved Towed Light Trucks

by Degree of Ejection, Crash Mode, and Area of Damage:

Average of Nationally Weighted Counts per Year, 1994-1996

Crash Mode and

Area of Damage

Complete

Ejection

Partial

Ejection Entrapment Total

Rollover 2,555,014 532,049 272,969 5,413,543

47.2% 9.8% 5.0% 37.0%

Nonrollover

 Single-Vehicle

 Front 332,549 99,429 302,974 2,224,462

14.9% 4.5% 13.6% 15.2%

 Side 68,142 146,592 139,640 673,111

10.1% 21.8% 20.7% 4.6%

 Rear, Top, or Under 87 0 10,975 14,986

0.6% 0.0% 73.2% 0.1%

 Multiple-Vehicle

 Front 56,032 159,534 316,014 3,730,416

1.5% 4.3% 8.5% 25.5%

 Side 529,300 84,621 67,037 2,184,444

24.2% 3.9% 3.1% 14.9%

 Rear 1,307 2,473 901 383,908

0.3% 0.6% 0.2% 2.6%

 Top or Under 0 0 8305 12493

0.0% 0.0% 66.5% 0.1%

Total 3,542,432 1,024,699 1,118,815 14,637,363

24.2% 7.0% 7.6% 100.0%

*For each crash mode, the first data row shows the number of occupants ejected or entrapped and the second row

shows the percentage of the row total.
Occupant Injury Data

National Automotive Sampling System/Crashworthiness Data System 1994-1996 53

0% 5% 10% 15% 20% 25% 30%

Ejection Rate

All Crash Modes

Rear

Side

Frontal

Side

Frontal

Complete Ejection

Partial Ejection

Rollover

Nonrollover

Single-Vehicle

Multiple-Vehicle

Figure 13

Ejection-Induced Occupant Injury Rates for Crash-Involved

Towed Cars by Degree off Ejection and Crash Mode, 1994-1996
54 National Automotive Sampling System/Crashworthiness Data System 1994-1996

Appendix A. Glossary

AIS (Abbreviated Injury Scale)

An integer scale developed by the Association for the Advancement of

Automotive Medicine to rate the severity of individual injuries. The AIS

includes: 1=minor, 2=moderate, 3=serious, 4=severe, 5=critical, and

6=maximum (virtually untreatable). The scale does not explicitly denote a

fatal injury. An AIS rating of 7 (injured, severity unknown) is used when

sufficient information about an injury is not available.

Body Type

Refers to the individual classifications of motor vehicles by their design

structure based on definitions developed by the Society of Automotive

Engineers.

Crash

An event that produces injury and/or damage, involves a motor vehicle in

transport, and occurs on a trafficway or while the vehicle is still in motion

after running off the trafficway. In this report, crash and motor vehicle crash

are synonymous. To qualify for the CDS, all crashes must be reported by the

police to the state and involve a towed CDS applicable vehicle.

Crash Severity (delta-v is used as a measure of crash severity)

CRASHPC and OLDMISSPC are computer models that provide a measure of

crash severity in terms of delta-v (see Appendix D). In vehicle-to-vehicle

crashes, the models assume that the two vehicles approach each other at

an impact velocity, reach a common velocity, and then separate. Delta-v is

equal to the impact velocity minus the separation velocity. Other factors

being equal, the greater the delta-v during a collision, the greater the

potential for occupant injury.

Crashworthiness Data System Applicable Motor Vehicle

Refers to those motor vehicles classified as automobiles, automobile

derivatives, sport utility vehicles, van-based light trucks, and light

conventional trucks where the qualifying trucks must have a gross vehicle

weight rating (GVWR) of less than or equal to 10,000 pounds.

Ejection

Refers to persons being completely or partially thrown from the vehicle as a

result of an impact or rollover. Partial ejection refers to a situation where part

of the occupant's body remains in the vehicle. This does not apply to

occupants who are not initially in the seating compartment of the vehicle

(e.g., persons riding in pickup beds, boots of convertibles, or open tailgates),

since any ejection for them is coded as complete ejection.
Glossary

National Automotive Sampling System/Crashworthiness Data System 1994-1996 55

Entrapment

Refers to persons being partially or completely in the vehicle and

mechanically restrained by a damaged vehicle component. Jammed doors

and immobilizing injuries, by themselves, do not constitute entrapment.

Occupants pinned by cargo shift are not considered to be entrapped.

Occupants who are completely or partially ejected and subsequently

become pinned by their own vehicle and any surface other than their own

vehicle are not considered entrapped. An occupant whose seat belt buckle

release mechanism is jammed as a result of a crash is not considered

entrapped.

Fatally Injured Occupant

A death within 30 days of a CDS applicable motor vehicle crash is a result of

injuries sustained in the crash.

Fatal Motor Vehicle Traffic Crash

A crash in which at least one occupant of a CDS applicable motor vehicle

dies within 30 days of the crash as a result of injuries sustained in the crash.

Fixed Object

An object attached to the terrain (trees, abutments) or stationary objects

intentionally placed for a particular purpose (e.g., poles, barriers).

Gross Vehicle Weight Rating (GVWR)

The maximum capacity of a vehicle, including the weight of the base

vehicle, all added equipment, driver and passengers, and all cargo loaded

into or onto the vehicle. Actual weight may be less than or greater than

GVWR.

Injured Occupant

Occupant of a CDS applicable motor vehicle sustaining any type of injury as

a result of a crash, including injuries from non-impact forces.

Light Trucks

Includes utility vehicles, pickups, vans, and truck-based station wagons, with

a GVWR less than 10,000 pounds.

Maximum AIS

Represents the highest AIS level sustained by an injured occupant of a CDS

applicable motor vehicle.

Motor Vehicle in Transport

A CDS applicable motor vehicle on a roadway or in motion within a

trafficway.

Non-Fixed Objects
Glossary

56 National Automotive Sampling System/Crashworthiness Data System 1994-1996

Objects that are movable or moving that include motor vehicles,

pedestrians, pedalcyclists, animals, trains, trailers, ojects that fall from

vehicles, small boulders, trash cans, or grocery carts.

Occupant

Any person who is in a CDS applicable motor vehicle in transport.
Glossary

National Automotive Sampling System/Crashworthiness Data System 1994-1996 57

Passenger Car

Any motor vehicle that is an automobile, auto-based pickup, large

limousine, or three-wheel automobile or automobile derivative.

Passenger Vehicles

Includes passenger cars, pickup trucks, vans, and sport/utility vehicles with a

GVWR less than 10,000 pounds. Equivalent to CDS applicable vehicles.

Police-Reported Crash

A crash investigated or reported by a police officer, documented with a

completed form which is signed by the investigating officer, and reported to

the state. Driver reports submitted only to motor vehicle officials are

excluded.

Primary Sampling Unit (PSU)

A city, county, or group of contiguous counties with an aggregate

population of at least 50,000 which defines a geographic area for crash

investigation. PSU selection is the first stage in the probability sampling of

crashes for the CDS.

Belt Usage

Manually operated belt systems include shoulder belts, lap belts, lap and

should belt combinations, or child safety seats. Automatic belt systems

include passive belts.

Roadway

That part of a trafficway used for motor vehicle travel or, where travel by

various classes of motor vehicles is segregated, that part of a trafficway used

by a particular class. The roadway excludes shoulders, designated parking

lanes, and median areas.

Serious-Maximum Injury

Injury severity of AIS 3-6, including, for example, compound fractures and

internal organ injuries. Unless otherwise noted, summary statistics in this report

include all fatally injured persons as seriously injured, but exclude survivors

with unknown injury severity level (see AIS).

Towaway Crash

A crash which is noted on the police report as involving at least one CDS

applicable vehicle that was towed from the crash scene as a result of

damage from the crash. For those crashes involving injury or fatality, the

injured or killed person must be an occupant of the towed CDS applicable

vehicle to qualify for the CDS.

Towed Vehicle

A CDS applicable motor vehicle that was involved in a crash and removed

by means other than its own power from the crash scene due to damage

resulting from the crash.
Glossary

National Automotive Sampling System/Crashworthiness Data System 1994-1996 59

Trafficway

Any right-of-way open to the public as a matter of right or custom for moving

persons or property from one place to another, including the entire width

between property lines or other boundaries.

Vehicle Type

Refers to a series of CDS applicable motor vehicle body types that have

been grouped together because of design similarities. The principal vehicle

types used in this report are passenger cars, pickup trucks, vans, and

sport/utility vehicles.
60 National Automotive Sampling System/Crashworthiness Data System 1994-1996

Appendix B. NASS/CDS Sample Design

The crashes investigated in NASS/CDS are a probability sample of all police-reported

crashes in the United States. Each such crash that occurs within a CDS team's area

has a chance of being included in the sample. This design makes it possible to

compute not only national estimates but also probable errors associated with those

estimates. Many other features of the design have a significant impact on CDS data

analysis, the most important of which are highlighted in this appendix.

The selection of sample crashes for CDS is accomplished in stages. The first stage is

the selection of geographic areas called primary sample units (PSUs). Each PSU is

composed of a large city, a county, or a group of contiguous counties. The United

States was divided into 1,195 PSUs. The PSUs were then grouped into 12 categories

described by geographic region and degree of urbanization. Two PSUs were

selected from each category with probability proportional to its 1983 population.

These 24 PSUs are the first stage in the selection of CDS sample crashes.

If every crash in each of the 24 PSUs were investigated, a national estimate could be

obtained by weighting each crash in the PSU by the inverse of the probability of

selection of the PSU. For example, if a sample PSU had 1 chance in 40 of being

selected, then each crash from the PSU would be weighted by a factor of 40. This is

called the first-stage expansion factor.

It is not practical to investigate every crash in each sample PSU, so additional stages

of sampling are performed. The police agencies in a PSU are categorized by the

number and type of police crash reports they process. Sample police agencies are

then selected randomly from each category. The fraction of the agencies selected

increases as the number and severity of crashes reported by the agency increases.

This is called the second-stage expansion factor.

The final stage of sampling is the selection of crashes from all crashes reported in the

sample police agencies. A simple random selection of all reported towaway crashes

would result in a large percentage of sample crashes with property damage and few

injuries, since these constitute such a large fraction of all crashes. This type of sample

would not be effective in providing the detailed and accurate information needed

for the mitigation of crash consequences. Rather, a substantial sample of serious injury

crashes is needed for NASS/CDS.

The procedure used to obtain the desired sample by type and severity of crashes is

an unequal probability selection. This required listing police crash reports in categories

defined by most severe police-reported injury to an occupant of a towed CDS

applicable motor vehicle, disposition of the injured, and model year of the towed

CDS applicable motor vehicle. A weighting factor was assigned to crashes in each

category to increase or decrease the probability of selection. A random selection

was made from the total crashes listed in all categories. In addition to the

probabilities of selection varying by type of crash, other factors affected the selection

probabilities at this stage, such as the number of crashes listed, the date and time of

the crash, and the police agencies from which the
NASS/CDS Sample Design

National Automotive Sampling System/Crashworthiness Data System 1994-1996 61

crash was listed. The result was that each sampled crash from a PSU has a unique

selection probability.

The inverse of this probability is called the third-stage expansion factor. If each

sample crash in a PSU is multiplied by its second- and third-stage expansion factors,

an unbiased estimate of the total number of crashes in the PSU is obtained. To

produce the national estimates, the PSU level estimates are inflated by the first-stage

expansion factor. Thus, the national expansion factor is the product of the first-,

second-, and third-stage expansion factors.

The national estimates equal the inverse of the product of the probability of the PSUs

being selected, the probability of the police agencies being selected, and the

probability of the crash being selected for that day. Since the number of crashes in

the sample is predetermined, the national estimate for each crash within a stratum is

different. To account for this bias, a ratio weight was developed. The ratio weight is

the national estimate multiplied by a ratio factor. For each stratum, this ratio factor is

equal to the total number of crashes listed in all of the police jurisdictions (sampled

and non-sampled) divided by the number of crashes selected. There are instances

where very few or no crashes are listed. To account for this, the similar PSUs were

grouped together, based on the stratum from which they were originally selected.
62 National Automotive Sampling System/Crashworthiness Data System 1994-1996

Appendix C. NASS/CDS Data Elements

The data are collected on six forms: the Accident Form, the General Vehicle Form,

the Exterior Vehicle Form, the Interior Vehicle Form, the Occupant Assessment Form,

and the Occupant Injury Form. There are 310 different data elements in the

NASS/CDS that characterize the crash, vehicles, and the people involved. This

appendix includes the forms used for each crash in the CDS.

























































National Automotive Sampling System/Crashworthiness Data System 1994-1996 63

Appendix D. CRASHPC and OLDMISSPC Summary

CRASHPC is an acronym for Calspan Reconstruction of Accident Speeds on the

Highway. As its name implies, the CRASHPC program is a general-purpose personal

computer program that can be used to estimate vehicle speeds in real-world crashes,

based on physical evidence obtained by a crash investigator. The objective of the

CRASHPC program is to provide a standardized and objective means of interpreting the

physical evidence from the scene of an automobile collision.

Two separate and independent methods can be used to estimate the change in

vehicle speeds experienced by the vehicles. The first method makes use of trajectory

data and is based on work-energy relationships and the principle of conservation of

linear momentum. The other method makes use of detailed measurements of the

structural deformation of each vehicle to arrive at an estimate of the energy required to

produce the observed vehicle damage. These two methods can be used to check

each other, since they should yield similar results if the user possesses sufficient

information to use both methods fully.

The CRASHPC program is a simplified mathematical analysis of automobile crash events.

As is the case with any such analytical procedure, certain assumptions have been

made to reduce the complexity and the operating cost of the program. In some

particular cases, CRASHPC is not, nor was it intended to be, a high-fidelity collision

simulation program. In most crashes, only a minimum of data are available, and even

these data are only available second hand.

Beyond its use by Federal Government sponsored researchers, CRASHPC has become a

popular tool among reconstructionists involved in litigation, and much of the criticism of

the CRASHPC program regards its accuracy in such applications. CRASHPC was

intended as a statistical tool to identify and isolate problems in motor vehicle safety, not

as a simulation program, and it should be used accordingly. Often, accuracy problems

are the result of applying the CRASHPC program in situations which violate, to some

degree, its fundamental assumptions:

 It is a two-dimensional program.

 It simplifies the characteristics of vehicles.

 It assumes that at some instant during the impact both vehicles have a common

velocity.

 It assumes that the vehicles spin out to rest with constant rolling resistances, no active

steering, and over a single friction surface (a secondary friction surface may be

specified in the trajectory simulation).

The above assumptions mean that the program cannot be used for: rollovers;

sideswipes; severe override/underride crashes; nonhorizontal collision forces; or collisions

with large trucks or trains in motion, yielding objects, or pedestrians, bicyclists, or

motorcyclists.

The missing vehicle algorithm (OLDMISSPC) methodology is based on CRASHPC.
64 National Automotive Sampling System/Crashworthiness Data System 1994-1996

Appendix E. Harm Definition

“Harm” is a concept developed by Malliaris [1] for quantifying, or normalizing, the

relative consequences of the total estimated number of crash deaths and injured

people. Harm is commonly used for prioritization in crashworthiness program planning.

Harm attributes to each surviving injured person and each death a quantity based on

the costs (excluding property damage and travel delay costs) associated with each

death or injured person. The cost quantities are obtained from National average cost

estimates for injured people. National Harm estimates are developed by multiplying the

frequency estimates of the incidence of injured people at each severity level by the unit

cost estimates of the average losses for that severity of injury. These figures are then

summed to arrive at annual National Harm estimates.

Injury costs are estimated in accordance with the Abbreviated Injury Scale (AIS) of six

grades of increasing threat-to-life ranging from AIS 1 (Minor) to AIS 6 (Maximum). Table

E1 provides the latest “Economic Harm” figures associated with the maximum AIS for a

given crash victim using the latest NHTSA estimates of economic costs and injury

incidence. Table E2 provides Comprehensive Harm figures that include quantities

representing values for pain and suffering costs that are excluded in the “economic”

cost schedule.
Harm Definition

National Automotive Sampling System/Crashworthiness Data System 1994-1996 65

Table E1. 1994 Economic Harm from Crash Injuries

Survivor's

Maximum AIS

Unit Costs [2]

(1994 Dollars) Incidence [3]

Economic Harm [4]

(Billion Dollars)

 Minor 1 $3,777 4,626,495 $17

 Moderate 2 $31,164 398,553 $12

 Serious 3 $98,011 166,845 $16

 Severe 4 $221,494 17,123 $4

 Critical 5 $697,533 6,914 $5

 Fatalities 6 $822,328 40,676 $33

 1994 National Estimate of Total Economic Harm $87

Table E2. 1994 Comprehensive* Harm from Crash Injuries

Survivor's

Maximum AIS

Unit Costs [5]

(1994 Dollars) Incidence [3]

Comprehensive* Harm

(Billion Dollars)

 Minor 1 $10,840 4,626,495 $50

 Moderate 2 $133,700 398,553 $53

 Serious 3 $472,290 166,845 $79

 Severe 4 $1,193,860 17,123 $20

 Critical 5 $2,509,310 6,914 $17

 Fatalities 6 $2,854,500 40,676 $116

 1994 National Estimate of Total Comprehensive Harm $335

*Comprehensive cost estimates include economic cost components plus values for reduced

quality of life.

References

[1] Malliaris, A., ,Hitchcock, R, Hedlund, J, A Search for Priorities in Crash Protection, SAE,

820242, 1982.

[2] NHTSA, The Economic Cost of Motor Vehicle Crashes, 1994, DOT HS 808 425, July 1996,

Table 2, p. 8.

[3] NHTSA, The Economic Cost of Motor Vehicle Crashes, 1994, DOT HS 808 425, July 1996, Table 3, p. 9.

[4] NHTSA, The Economic Cost of Motor Vehicle Crashes, 1994, DOT HS 808 425, July 1996, Table 1, p. 7.

[5] NHTSA, The Economic Cost of Motor Vehicle Crashes, 1994, DOT HS 808 425, July 1996, Table A-1, p. 59.
66 National Automotive Sampling System/Crashworthiness Data System 1994-1996

Appendix F. Statistical Methods

Two aspects of the NASS/CDS statistics presented in this report are discussed in this

appendix. These aspects are:

Assigning crash type and general area of damage, and

The sampling errors for the weighted average counts over the 1994-1996 period.

The method for producing estimates from the 1994-1996 CDS data is to use national

ratio-adjusted weights. These sampling weights are appended to the CDS data on the

electronic data file. By summing the sampling weights for cases that have a certain

characteristic, an estimate of the national total for that characteristic can be produced.

Assigning Crash Type and General Area of Damage

Two different procedures were used to assign General Area of Damage (GAD1) where it was coded as unknown

in the NASS/CDS vehicle exterior (VE) form. The first method uses information from elsewhere in the

NASS/CDS data files, and the second imputes unknowns based upon a univariate distribution.

1. Assignment based upon other information in the NASS/CDS data files

The SAS program shown below was used to assign GAD1 from the Event file to vehicles where GAD1 is missing

of the VE file. The vehicles (towed cars and light trucks) can be classified into three groups with a

different approach for each:

For the first group, damage area was found by matching ACCSEQ1 on the VE form with ACCSEQ on the

Event file.

For the second group, that had no VE form, damage area was found by linking (using VEHNO on the GV

file and VEHNUM / OBJCONT on the Event file) to the only damage for that vehicle that was listed on the

Event file.

For the third group, that had no VE form and could not be linked through VEHNUM / OBJCONT, damage

area was found by identifying the collision partner in the delta V event, and using ACCSEQ1 from the

partner to link to the Event file (this partner was the only other light vehicle in the crash that had

delta V estimated by the missing vehicle algorithm for a collision with the vehicle in question).

The numbers of vehicles in the 3 year sample that were assigned GAD1 using this method are summarized as

follows:

Table F-1

Cars and Light Trucks with GAD1 Assigned from Event Form,

Unweighted Sample Count

Year method 1 method 2 method 3 Total

1994 79 120 24 223

1995 219 336 69 624

1996 223 385 67 675

Total 521 841 160 1522
Statistical Methods

National Automotive Sampling System/Crashworthiness Data System 1994-1996 67

SAS program assigning GAD from Event file:

*** run this program for each of the years needed, then 

combine final data sets (unkn94, unkn95, unkn96), sort 

by year psu caseno vehno, and merge with VE file to 

include newly assigned gad info ** ;

libname nass94 'd:\nass\nass94';

options ls=78 pagesize=500;

proc format;

value anydv

 0='DV unknown'

 1='DV known';

value veform

 0='No VE form'

 1='VE form';

value matchveh

 0='No match'

 1='Match';

data gvve1;

* Select towed light passenger vehicles,

 create a 0-1 variable (ANYDV) for delta V availability,

 create a 0-1 variable (VEFORM) for VE form availability;

merge nass94.gv nass94.ve(in=a);

by psu caseno vehno;

if 1<=bodytype<=49;

keep psu caseno vehno

 dvtotal accseq1 gad1 objcont1

 dvbasis anydv veform;

if dvtotal>=0 then anydv=1;

else anydv=0;

veform=a;

data gad_n1 gad_y1;

* Subset to vehicles with delta V estimated

 by the missing vehicle algorithm;

* Creat files for vehicles with GAD1 unknown (GAD_N1)

 and with GAD1 known and from a vehicle impact (GAD_Y1);

* This latter file will be used as a source of ACCSEQ1

 when there is no VE form for the other vehicle;

set gvve1;

if anydv=1 and dvbasis=3;

if gad1=' ' or gad1='9' then output gad_n1;
Statistical Methods

68 National Automotive Sampling System/Crashworthiness Data System 1994-1996

else if 1<=objcont1<=30 then output gad_y1;

data ve_y1 (keep=psu caseno vehno dvtotal accseq)

 ve_n1 (keep=psu caseno vehno dvtotal);

* From vehicles with delta V but not GAD1,

 create subfiles for those with (VE_Y1) versus

 without (VE_N1) a VE form;

* Rename ACCSEQ1 for merging with the Event file;

set gad_n1;

if veform=1 then do;

 accseq=accseq1;

 output ve_y1;

end;

else output ve_n1;

data vehveh1;

* Create a file with a record for each vehicle-damage

 combination listed on the Event file for collisions

 between two light passenger vehicles, and

 rename the variables so they can be merged and used

 with the combined GV-VE data selected above;

set nass94.event;

keep psu caseno vehno accseq gadev vehcont;

if 1<=vehnum<=30 and 1<=class1<=49

 then list1='LV';

if (1<=objcont<=30 and 1<=class2<=49) or objcont=70

 then list2='LV';

if list1='LV' and list2='LV';

vehno=vehnum;

gadev=gadev1;

vehcont=objcont;

output;

if list2='LV' then do;

 vehno=objcont;

 gadev=gadev2;

 vehcont=vehnum;

 output;

end;

proc sort data=vehveh1;

by psu caseno vehno accseq;

data ve_y2;

* For vehicles with an estimated delta V, with a VE form,

 with ACCSEQ1 coded, but with GAD1 unknown, merge with

 the Vehicle-Event file using the renamed ACCSEQ variable;

merge ve_y1(in=a) vehveh1;

by psu caseno vehno accseq;
Statistical Methods

National Automotive Sampling System/Crashworthiness Data System 1994-1996 69

if a=1;

data ve_n2;

* For vehicles with an estimated delta V, but without a VE form,

 merge with the Vehicle-Event file using the renamed VEHNO

variable;

* This produces more than one record per vehicle

 for those vehicles with more than one vehicle-vehicle

collision;

merge ve_n1(in=a) vehveh1;

by psu caseno vehno;

if a=1;

data ve_n_s1(keep=psu caseno vehno

 dvtotal accseq gadev vehcont)

 ve_n_m1(keep=psu caseno vehno

 dvtotal);

 * For vehicles with an estimated delta V, but without a VE form,

 separate into those with only one versus more than one

 vehicle-vehicle collision;

set ve_n2;

by psu caseno vehno;

if first.vehno*last.vehno=1 then output ve_n_s1;

else output ve_n_m1;

data ve_n_m2;

* Remove redundant entries for the identification

 file of vehicles without a VE form,

 and with more than one vehicle-vehicle collision;

set ve_n_m1;

by psu caseno vehno;

if first.vehno;

matchno=vehno;

data gad_y2;

* Vehicles with delta V estimated by the missing vehicle

algorithm

 and with a VE form are a source of ACCSEQ1 for the other

vehicle

 when that other vehicle has no VE form;

set gad_y1;

keep psu caseno partner matchno accseq;

partner=vehno;

matchno=objcont1;

accseq=accseq1;

proc sort data=gad_y2;
Statistical Methods

70 National Automotive Sampling System/Crashworthiness Data System 1994-1996

by psu caseno matchno;

data ve_n_m3;

* For vehicles with delta V estimated by the missing vehicle

algorithm,

 without a VE form, and with more than one vehicle-vehicle

collision,

 add ACCSEQ1 from the impacting vehicle involved;

merge ve_n_m2(in=a) gad_y2(in=b);

by psu caseno matchno;

if a=1;

matchveh=b;

drop matchno;

data ve_n_m4 leftovr1;

* For vehicles with an estimated delta V, but without a VE form,

 and with more than one vehicle-vehicle collision,

 and with ACCSEQ1 added from the impacting vehicle,

 separate leftover vehicles with more than one collision

 identified in this manner;

set ve_n_m3;

by psu caseno vehno;

if matchveh=1 and first.vehno*last.vehno=1

 then output ve_n_m4;

else output leftovr1;

data ve_n_m5;

merge ve_n_m4(in=a) vehveh1;

by psu caseno vehno accseq;

if a=1;

data unkn94; set ve_y2 ve_n_s1 ve_n_m5; year=94;

proc freq data=unkn94; tables gadev /missing;

run;
Statistical Methods

National Automotive Sampling System/Crashworthiness Data System 1994-1996 71

2. Assignment of crash type and GAD1 based upon imputation

The unknowns remaining after performing the above procedure were imputed based upon a univariate

distribution of crash type. The table below illustrates the steps taken.

Table F-2

Imputation of Unknown GAD1 and Crash Type,

Towed Light Trucks, Total Sample for 1994-1996

row Crash Type step 1 step 2 percent

1 rollover 1-3 578 613 11.8%

2 rollover 4+ 418 444 8.6%

3 rollover e/e 15 16 0.3%

4 rollover ? 62

5 rollover total 1073 1073 20.7%

6 single front 450 679 13.1%

7 single side 93 140 2.7%

8 single rear 9 14 0.3%

9 single t/u 0 0 0.0%

10 single gad? 281

11 single total 833 833 16.1%

12 multi front 1709 2380 46.0%

13 multi side 497 692 13.4%

14 multi rear 141 196 3.8%

15 multi t/u 2 3 0.1%

16 multi gad? 922

17 multi total 3271 3271 63.2%

18 total 5177 5177 100%

The column "step 1" shows the univariate distribution, including unknowns, from the CDS

data set after running the SAS program described above. The column "step 2" has the 3

types of unknowns (rollover, type unknown, single vehicle crash with unknown GAD, and

multi-vehicle crash with unknown GAD) redistributed into the major crash types

according to the proportion of known crash types for that group. For example, the 62

light trucks shown in "step 1", row 4, are redistributed among rows 1 through 3 in “step 2.”
Statistical Methods

72 National Automotive Sampling System/Crashworthiness Data System 1994-1996

Standard Errors of the CDS Estimates

The national estimates produced from the CDS data may differ from the true values, because they are based

on a probability sample of towed cars and not a census of all crashes. The size of these differences may

vary depending on which sample was selected. The standard error of an estimate is a measure of the

precision or reliability with which an estimate from this particular CDS sample approximates the result of a

census.

It is impractical to compute and provide a standard error for each estimate in this report. Instead,

generalized standard errors for estimates of totals are presented in the following two tables for vehicle

characteristics (Table F3) and for occupant characteristics (Table F4). The generalized standard error

tables were produced separately for the vehicle and occupant tables, using three steps.

1. The standard errors for selected estimates in the report were calculated using a Taylor series

approximation.

2. An equation that best fit the standard errors was found using regression techniques.

3. Approximate standard errors were generated from this equation, and the generalized standard error

tables were produced.

Shown in each table are the values for the estimates and an estimate of one standard error for that value

derived from the 1994-1996 CDS data. By adding and subtracting one standard error to the associated

estimate, approximate 68% confidence intervals for an estimate can be created. The estimated annual

average number of small, crash-involved, towed cars is given in Table 1 of the report as 846,069 cars. To

calculate one standard error for this estimate, use Table F3 in this appendix. Since 846,069 does not appear

in Table F3, use linear interpolation from the standard error values for the estimates 800,000 and 900,000. 

One approximate standard error would be 83,400+4,508=87,908. The confidence interval for this estimate

would be 846,069 +or- 87,908 or 758,161 to 933,977. 

The formula used to compute the standard errors is presented below each table. More information on

standard error estimates can be obtained from the National Center for Statistics and Analysis.
Statistical Methods

National Automotive Sampling System/Crashworthiness Data System 1994-1996 73

Table F3

Crash-Involved Vehicle Characteristics Estimate and Standard Errors

Estimate Standard Error Estimate Standard Error

500 500 100,000 13,600 

1,000 700 200,000 24,100 

5,000 1,700 300,000 34,200 

10,000 2,600 400,000 44,100 

20,000 4,100 500,000 53,900 

30,000 5,500 600,000 63,800 

40,000 6,800 700,000 73,600 

50,000 8,000 800,000 83,400 

60,000 9,100 900,000 93,200 

70,000 10,300 1,000,000 103,100 

80,000 11,400 1,100,000 113,000 

90,000 12,500 1,200,000 122,900 

!"# $ !"# $ + %&'% (()

Where

a= 4.922079

b= 0.034691

x= estimate

SE= Standard Error
Statistical Methods

74 National Automotive Sampling System/Crashworthiness Data System 1994-1996

Table F4

Crash-Involved Occupant Characteristics Estimate and Standard Errors

Estimate Standard Error Estimate Standard Error

500 300 100,000 19,000 

1,000 400 200,000 40,100 

5,000 1,200 300,000 63,300 

10,000 2,200 400,000 88,300 

20,000 4,000 500,000 115,000 

30,000 5,800 600,000 143,000 

40,000 7,600 700,000 172,500 

50,000 9,400 800,000 203,200 

60,000 11,300 900,000 235,200 

70,000 13,200 1,000,000 268,200 

80,000 15,100 1,100,000 302,400 

90,000 17,000 1,200,000 337,600 

!"# $ !"# $ + %&'% (()

Where

a= 3.837986

b= 0.04538

x= estimate

SE= Standard Error