Automobile Collision Data: An Assessment

of Needs and Methods of Acquisition

February 1975

NTIS order #PB-244867
TECHNOLOGY ASSESSMENT BOARD Congress of the United States EMILIO 0. DADDARI O

OLIN E. TEAGUE, TEXAS, CHAIRMAN DIRECTOR

CLIFFORD P. CASE, N.J., VICE CHAIR MAN OFFICE OF TECHNOLOGY ASSESSMENT DANIEL V. De SIMON E

EDWARD M. KENNEDY. MASS. MORRIS K. UDALL, ARIZ. WASHINGTON , D.C. 20510 DEPUTY DIRECTOR

ERNEST F. HOLLINGS, S.C. GEORGE E. BROWN, JR., CALIF.

HUBERT H. HUMPHREY. MINN. CHARLES A. MOSHER, OHIO

RICHARD S. SCHWEKER, PA. MARVIN L. ESCH, MICH.

TED STEVENS. ALASKA MARJORIE S. HOLT, MD.

EMILIO Q. DA DADDARIO

The Honorable George H. Mahon

Chairman

Committee on Appropriations 

U. S. House of Representatives” 

Washington, D. C. 20515 .

Dear Mr. Chairman:

On behalf of the Board of The Office of Technology Assessment,

we are pleased to forward to you the following report on

Automobile Collision Data. This study was requested as an

evaluation of the automotive crash recorder program proposed

by the National Highway Traffic Safety Administration (NHTSA).

As the assessment progressed, the implications for automobile

collision data as a “whole became apparent and the report has

been so titled to provide a more accurate indication of its

scope.

This report is being made available to your Committee in

accordance with Public Law 92-484.

Respectfully yours,

Chairman Vice

Technology Assessment Board
...——

.

.

PREFACE

Highlights of the study findings which are especially relevant

to the four questions posed by the House Appropriations Committee

in its letter of request are summarized below. (The Committee

letter is appended).

1.

2.

Cost and Adequacy of Current NHTSA Programs

The National Highway Traffic Safety Administration has

spent a total of $15.8 million during the last three years

gathering and analyzing automobile crash data. The data

collected by NHTSA is inadequate to provide a basis for

effective safety standard setting or measurement of the

benefits of the standards in force. The inadequacies of

the system are: too few reports are gathered too slowly;

the file is biased toward severe injury accidents; reports

do not include adequate quantitative measures of causal

severity; and, the information recorded in accident reports

is not that which is essential to answering the specific

questions of rulemakers, accident researchers and car

designers.

Use of Existing Crash Recorders

There are 1800 installed (disk-type) crash recorders.

These provide a 3-axis acceleration time history over the

actual impact interval. This information would probably

be adequate to determine crash severity had a severity

index been explicitly defined. After the index is defined,

these same recorders might be used as part of a specialized

crash severity research program.

Currently these recorders provide a limited independent

measure of crash severity in air–bag equipped cars. They are

also giving NHTSA practical experience in the retrieval,

readout and analysis of crash records, the reliability of

recorders themselves, and the reactions of fleet owners to

crash recorder installations.

- i -
●

✎

3*

●

●

Improving the Data Base

NHTSA has not provided a sampling plan to support

requested appropriations for crash data acquisition programs

in the last three years. In order to rectify the inadequacies

of the existing data base and the current crash data

acquisition system, a comprehensive sampling plan must be

developed. 

The rate of acquisition of collision reports should be

, increased to 500,000 to 1,000,000 per year at an estimated

cost of $3-10 million annually. Causal severity should be

measured and reported. This could be done by using disk

recorders at a cost per report of about $133. Alternately,

vehicle deformation could be measured and analyzed to determine severity at a cost of about $20 per report. However,

if a cheap crash severity measuring device could be developed,

it would eliminate the tedious measurement and analysis of

vehicle deformation.

The consequences of not getting data are, first, Sus- -

taining a continuing societal l0SS of at least $22 billion

per year in automobile death, injury and damage without 

developing adequate tools to correct the problem; and second,

imposition of $7 billion to $14 billion in consumer costs for

meeting existing, proposed, and planned future motor vehicle

safety standards whose benefits will continue to be uncertain.

Current NHTSA programs (multidisciplinary accident

investigation, air cushion restraint system evaluation,

fatal accident reporting, pedestrian-cyclist accident

survey) should be continued. They are necessary to

answer specific safety questions. . . . _

4. Further Considerations

If sophisticated tape crash recorders were used, there

may be secondary benefits to driver training programs. For

example driver errors may be more readily determined and the

effectiveness of driver training may be better measured.

If crash recorders are installed, there is the possibility . .

that their readings could be used in liability cases. This

matter should be examined more fully in the legislative process.

- ii -
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Edward M. Kennedy

Technology Assessment Board

Washington, D. C. 20510

Dear Mr. Chairman: 

On behalf of Congressman John J.

Transportation Subcommitee, and

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McFall, Chairman

Congressman Silvio O.

of the

Conte, the Subcommittee's Ranking Minority Member, I am

transmitting the attached request for a technology

assessment with regard to automobile crash recorders.

with kindest personal regards. .

-

—.—

MAJORITY MC M0CR8

GEORGE H. MAHON. TEX.,

CMAINMAS4

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November 19, 1974

Honorable George H. Mahon

Chairman

Committee on Appropriations

U.S. House of Representatives

Washington, D. C.

Dear Mr. Chairman:

The Conference Report to H.R. 15405 (Department of

Transportation and Related Agencies Appropriations Bill,

1975) states that: “The conference agreement contains no

funds for the crash recorder program. The Committee

intends to request an evaluation of this program by the

Office of Technology Assessment. “

The purpose of this program, as proposed by the National

Highway Traffic Safety Administration (NHTSA) , is to assemble

detailed data on actual collisions so as to develop realistic

automobile design standards. NHTSA proposed the installation

of 100, 000 crash recorders in vehicles used in ordinary

driving. Total cost of the 5 year program including

installation of the recorders and monitoring and analysis

of the data was estimated at $14.5 million in 1973. An

alternate approach has also been proposed by NHTSA. This

entails the controlled crashing of unoccupied vehicles along

with computer s emulations o f automobile crashes. The cost

of this program has been estimated as approximately the same

as the crash recorder program.

Although the committees of both Houses have heard extensive

testimony on this program over the past three years,

substantial question and differences still exist on the

necessity for gathering additional information through the

installation and monitoring of the requested crash

. recorders.

- iv -
.-

Page 2 - Honorable George H. Mahon ●

Since this issue remains unresolved, the Conference Committee

on H.R. 15405 decided to call upon the Office of Technology

Assessment for assistance.

We therefore request that the Technology Assessment

consider approving an assessment that would address

following issues:

1.

2.

3.

4.

Board

the

How much has NHTSA spent in each of the past three

years to gather accident data? Is that data sufficient,

or is further data on the characteristics of automobile

collisions necessary for effective NHTSA standardssetting? If the existing data base is inadequate; in

what ways is it inadequate?

An evaluation of the type of data being produced by

existing crash recorders and an explanation of how

this data is being used by NHTSA should be conducted.

If the data base is inadequated, how might an adequate

data base be obtained and what are the consequences

associated with obtaining the data in different ways

(including the possibility of not obtaining the

necessary data)? The cost effectiveness of the

crash recorder and the crash impact approaches

proposed by NHTSA should be examined.

Secondary consequences of implementing these or

other program should be identified and evaluated.

Examples of these secondary consequences include

legal questions associated with the existence of

actual physical data from an accident and the

potential value (to driver training program) of

a knowledge base concerning how drivers actually

respond in accident situations. For each type of

approach investigated, the implementation costs to

the Federal Governmentt industry and consumers should

be identified.

We appreciate your assistance in transmitting this

the Chairman of the Technology Assessment Board.

Sincerely,

John J. McFall

Chairman, Subcommittee on

Transportation Appropriations

(signed)

request to

Silvio O. Conte

Ranking Minority Member

Subcommittee on Transportation

Appropriations

- v -
Contents

In this volume:

1. Introduction and Summary

2. The Need for Mere and Better Crash Data

3. Characteristics of An Adequate Data

Collection Program

4. Alternatives For An Adequate Data

Acquisition Program

5. Federal Responsibility and Expenditures

For Collision Data Gathering

6. Legal Aspects of Crash Recorders

References

Bound Separately:

Appendices

Page

1

9

26

49

64

68

70

- vi -
Auto Collision Data

February 17, 1975

Page 1

1. INTRODUCTION AND SUMMARY

At the request of the House Appropriations Committee, the

Office of Technology Assessment, through contract OTA-C1l,

engaged Economics & Science Planning, Inc. (ESP) to undertake

a study of the need for and means to assemble detailed data on

actual automobile collisions so as to develop realistic automobile

design standards. The study examined the desirability, utility,

design and cost of crash recorders and of the alternate approaches

to gathering collision data, including computer crash simulation,

controlled laboratory crashes and their correlation with observed

vehicle deformations, and methods to improve the accuracy of accident investigation reporting and to increase the utility of national

crash data files. Specific data collection programs previously

proposed to Congress by the National Highway Traffic Safety

Administration were studied and evaluated. This report contains

the results of this effort.

We have concluded that the current national accident data

base is inadequate to resolve the uncertainties in NHTSA’s current

and proposed motor vehicle safety programs. One of the major

deficiencies is data relating collision forces and actual fatalities

and injuries. The need has been clearly expressed by Professor

B. J. Campbell (University of North Carolina):

!1 .00 when one is forced to use nonhuman subjects [in

laboratory crashes] then one is left in the situation of

knowing a great deal about the physics of the crash but

knowing little of the actual injuries that might have

occurred in such a crash. On the other hand, in real

world automobile crashes one can learn about the actual

outcome in terms of survival and injuries, but the

input variables mentioned before are unknown.
Auto Collision Data

February 17, 1975

Page 2

“The need to link these two systems is apparent.

Engineers who design protective systems need to know

about stopping distances, forces, decelerations, etc.

But knowing these things is of too little help unless

one has a way to relate them to real world injuries.”

FINDINGS

1. The existinq national data base is inadequate

--

--

--

only four of 40 existing standards have been shown to

be beneficial based on statistical evidence.

the nationwide effectiveness of lap belts in mitigating

fatalities is still unknown after five years; statistical

evidence is available from only one state.

there is an immediate need for more and better crash

data

o to support rulemaking and to estimate the benefits

of proposed safety standards

o to determine the effectiveness of existing safety

standards

o to determine causes of accident, injury and fatality

to aid crashworthy vehicle design

o to identify new safety problems as they develop

o for predicting the impact of trends in motor vehicle

design on accident incidence and outcome
Auto Collision Data

February 17, 1975

Page 3

.- Larger crash data collection expenditures than the

$5 million to $6 million now programmed annually

appear to be justified:

o Motor Vehicle accidents cost society $22 billion

to $44 billion annually.

o Present safety standards cost consumers $2.5 billion

annually

o proposed and possible safety standards could cost an

additional $4 to $12 billion annually.

o Present and planned safety standards add weight to

automobiles which increases gasoline consumption.

2. A Comprehensive Accident Data Program

-- must be designed with great care to assure that

o it is representative and avoids inadvertant biases

o it will answer the outstanding critical safety questions

o it is adequate in rate and quantity

o it provides uniformity in reporting and format

-- should be reviewed and approved by a broadly based body

of experts before it is implemented.

-- elements for a comprehensive program could include:

o 500,000 to 1,000,000 crash reports per year for a

mass data file at a cost of $3 to $10 million per year.
Augo Collision Data

February 17, 1975

Page 4

0 the measurement and reporting of crash severity

either by vehicle deformation measurement or a

cheap and widely installed crash severity recorder,

at a cost of $10 to $20 million per year.

o some measurement of crash dynamics using some mix of

simulated accident reconstruction (SMAC) and

collision history (disk or tape) crash recorders at

a cost of $2 million to $4 million

o supplementary surveys to answer specific questions

and the existing special programs now costing $5 to

$6 million per year

o a cheap crash severity recorder at a development cost

of about $500,000

0 field trials of planned safety improvements whose

costs are high and whose benefits are uncertain (as

an example, the cost of a field trial of passive

restraints would be $30 - $60 million)

3. The Federal Government, not States, manufacturers or insurance

companies, should support the central data collision activities.

.- It is a national problem.

-- The Motor Vehicle Safety Standards are promulgated by the

Federal Government.

-- The data has to be obtained in an unbiased and uniform

manner throughout the nation.

-- The Federal Government has the resources and ready access

to the sources of information.
—— ———

Auto Collision Data

February 17, 1975

Page 5

4. Crash recorders provide data that may be admissible in

a court of law.

5. Proqram alternatives include the following:

o Doinq nothing to improve the current crash data

acquisition system. If this course is followed, $22

to $44 billion in societal losses will continue to be

incurred each year without developing adequate tools

to analyze and correct the problem; $7-14 billion or

more in consumer costs will be imposed yearly by current,

proposed and advanced motor vehicle safety rule making

whose benefits, in most cases, will continue to be

uncertain.

o Upgrading current data collection programs without adding

a mass data acquisition system. This course will neither

provide statistically convincing measures of the reduced

incidence

of safety

questions

of death or injury resulting from incorporation

features nor will it give a timely response to

regarding the impact of vehicle design changes.

o Providing a mass accident data acquisition proqram at a

cost of $3 to $10 million yearly. This course will begin

to permit timely statistical determination of safety system

benefits and identification of automotive safety problems.

However, crash severity measures will be inadequate and

it will be difficult to associate injury with crash severity.

o Upgrading mass accident data acquisition proqram to provide

accurate severity reportinq at a cost of $10 to $20 million

annually. This action would finally provide timely

determination of safety benefits with ascertainable accident

severity incidence and associated injury and fatality

exposure bridging the gap between laboratory and field

experience.
Auto Collision Data

February 17, 1975

page 6

0 Use of acceleration time-history (disk) recorders. A — —.

small (10,000 to 20,000 recorders; $2-4 million)

program will permit: generating baseline statistical

information such as severity distribution of all collisions;

the calibration of vehicle deformation estimates as a

severity measure; and calibration of computer simulated

crash reconstruction (SMAC). A program as large as

large as 100,000 disk recorders -- $10 million -- would

overdo it from the standpoint of research and be

inadequate from the standpoint of mass data gathering.

Development of a cheap and proliferable causal severity

measurement device at an estimated development cost of

$500,000 and a production cost of approximately $2 per unit

will provide a device capable of widespread installation

that permits ready read out of crash severity magnitude and

direction by an untrained investigator. The need for

careful deformation measurement and transformation of these

measurements to equivalent barrier speed would be

eliminated.

providing a federally sponsored field trial of uncertain

and/or expensive safety aids. This program will permit the

evaluation of safety aids, where normal market forces do

not operate, prior to their being mandated on a national

scale. (In the case of passive restraints, the one time

cost would be $30 - $60 million. )

This study was accomplished by an extensive literature survey;

by independent analysis by members of the ESP staff; by analysis

of specific assigned topics undertaken by knowledgeable members

of the automobile accident research community; and through an

Automobile Collision Data Workshop, convened January 16 and 17,

1975, at which the requirements for, and various approaches to,

better collision data gathering were presented and discussed in

depth by experts in all aspects of the problem. Individuals who

participated in the Workshop were the following:
— ——-—

Auto Collision Data

February 17, 1975

Page 7

Lynn Bradford

Paul Browinski

B. J. Campbell

Charles Conlon, Jr.

J. Robert Cromack

John Edwards

M. D. Eldridge

Vincent J. Esposito

William Fitzgerald

John Garrett

Howard P. Gates, Jr.

Lawrence A. Goldmuntz

Walton Graham

James Hofferberth

John F. Hubbard, Jr.

Paul R. Josephson

Charles Kahane

Edwin A. Kidd

Phil Klasky

Gene G. Mannella

Don Mela

National Highway Traffic Safety

Administration

AVCO Systems Division

Highway Safety Research Center

University of North Carolina

AVCO Systems Division

Southwest Research Institute

Ford Motor Company

National Highway Traffic Safety

Administration

National Highway Traffic Safety

Administration

AVCO Systems Division

Calspan Corporation

Economics & Science Planning, Inc.

Economics & Science Planning, Inc.

Economics & Science Planning, Inc.

National Highway Traffic Safety

Administration

Center for Auto Safety

Center for Auto Safety

National Highway Traffic Safety

Administration

Calspan Corporation

Teledyne Geotech

National Highway

Administration

National Highway

Administration

Traffic Safety

Traffic Safety
—

Auto Collision Data

February 17, 1975

page 8

Charles A. Moffatt

David Morganstein

James O’Day

Brian O’Neill

L. M. Patrick

Steven J. Peirce

Louis W. Roberts

A. J. Slechter

John Versace

Richard Wilson

National Highway Traffic Safety

Administration

Center for Auto Safety

Highway Safety Research Institute

University of Michigan

Insurance Institute for Highway

Safety

Wayne State University

National Highway Traffic Safety

Administration

Transportation Systems Center,

Department of Transportation

Ford Motor Company

Ford Motor Company

General Motors Safety Research and

Development Laboratory

We wish to acknowledge our gratitude to these individuals

not only for their participation in the Workshop, but for their

continuing assistance during the study effort and preparation

of this report.
-— —— .——

Auto Colllslon Data

February 17, 1975

Page 9

2. THE NEED FOR MORE AND BETTER CRASH DATA

The following paragraphs will discuss the general objectives

of crash data collection, identify some specific data needs that

are not now satisfied, and point out serious inadequacies in the

current data file and acquisition systems. It will be shown that

these needs and limitations lead to a requirement for mass

acquisition of crash data, supplemented by special surveys and

large scale real-life experiments.

a. THE OBJECTIVES OF COLLISION DATA COLLECTION

The cost to society of automobile death and injury is con2/ servatively estimated— at $17 billion annually. The vehicle

3/ damage adds at least another $5 billion yearly–. The total,

$22 billion per year, corresponds to an average of $2200 in

losses per each U.S. automobile during its lifetime.

The specialists in auto safety have, as their concerted

objective, the reduction of this enormous waste. A body of

collision data is needed that will provide a substantial part of

the means to determine the causes of accidents, of injuries, and

of damage.

Professor Lawrence Patrick of Wayne State University 

expressed the consensus view of the Workshop participants as follows:

“PREMISE

1. The only valid way to establish safety needs

for automobiles is through examination of field data.

2. The only valid way to evaluate the effectiveness

of safety measures is through analysis of their effect on

accident data.

CONCLUSION

Accident data are essential.”
—

Auto Collision Data

February 17, 1975

Page 10

The National Highway Traffic Safety Administration is responsible, under the National Traffic and Motor Vehicle Safety Act of

1966,* for the promulgation of Federal Motor Vehicle Safety

Standards to which vehicles manufactured for sale or use in the

United States must conform. Under the Motor Vehicle Information

and Cost Savings Act (1972)** the Secretary of Transportation is

also responsible for setting standards for damage-limiting

bumpers and for evaluating automobile damageability and

crash-worthiness.

Safety standards put into effect to date cost the consumer

4/ about $2.5 billion annually— and standards proposed will cost

2/, 4-/ another $4 billion or more each year— ● In addition,

standards suggested in Advance Notice of Proposed Rulemaking

would cost $4 billion per year in first costs plus another

$4 billion in added fuel costs when fully implemented. While the

more than 40 existing standards , which were based on intuition,

judgment and limited experience, are believed to yield in the

2/ aggregate a societal benefit greater than their consumer cost,—

only four of them (seat belts, energy absorbing steering column,

HPR glass and head restraints) have been shown by any authority to

be beneficial based on convincing statistical evidence. The

problem is that the body of data is inadequate.

Thus an initial objective of crash data collection and analysis

from the standpoint of the Government rulemaker, is that of evaluat–

ing the efficacies of the existing standards to determine which

should be kept on the books and which should be eliminated.
— ..—

Auto Collision Data

February 17, 1975

Page 11

A second objective from the standpoint of rulemaking is that

of providing the necessary statistical support to estimates of

benefits of a projected safety or damage-limiting standard. In the

next section there will be discussed a projected rule that is

controversial because of inadequate supporting data.

A third objective is the early identification of problem areas

in automobile damage and injury so as to permit designing effective

motor vehicle and highway safety programs.

The foregoing objectives from the standpoint of rulemaking have

their parallel from the standpoint of the automobile manufacturers.

8/ C. Thomas Terry of General Motors has summarized – the objectives

of gathering accident data in the field:

a. Evaluation of production safety systems.

b. Prediction of performance of proposed safety systems.

c. Identification of problem areas and evaluation of

proposed solutions on a cost/benefit basis.

d. Estimation of human tolerance to impact.

Automobile manufacturers are , of course, vitally concerned with

the relative merits of specific alternative designs as well as with

the validation of Safety Standards to which they are required by law

to conform.

A number of universities and institutes, both profit and nonprofit, have been for years involved in research in accident

causation, injury causation and designs of vehicles and roads that

will reduce accidents and injuries. They need accident data to

discover causes of accidents and injuries; armed with this information

they can accomplish and test in their laboratories design modifications and provide valuable advice to NHTSA and automobile manufacturers.
—

Auto Collision Data

February 17, 1975

Page 12

Finally, there is a need for national planners to predict the

impact of new trends in automobile designs. Fuel and resource

conservation programs, encouraged if not mandated by the Federal

Government, will lead to lighter, lower power-to-weight ratio

automobiles. Data on collision frequencies and outcome are needed

as a function of these parameters to inform Federal officials.

b. UNSATISFIED NEEDS FOR CRASH DATA

The body of specialists concerned with automobile collisions

-- the rulemakers, safety researchers, accident statisticians,

car designers, insurers, and public interest people -- overwhelmingly agrees that there is a grave and compelling need for more

and better crash data. The need

1/ of CALSPAN Corporation— in the

“It is essential that NHTSA

is expressed by Dr. Edwin A. Kidd

following way:

have a data bank for

surveillance and effectiveness studies related to

the impact of standards on accident, injury and fatality

frequencies. The relatively small output of the special

federal teams and/or the higher quantity, but low content

State data banks are inadequate for the purpose. In

addition to information on the general accident environment, vehicle damage and occupant injuries, details of

the impact environment -- velocity at impact, change in

velocity during impact and possibly, vehicle deceleration

-- are required for a sample of 100,OOO to 500,000

automobiles annually.”
—

Auto Collision Data

February 17, 1975

Page 13

Professor B. J. Campbell, Highway Research Center, Univer10/ sity of North Carolina— , states:

“In acquiring automobile accident data several

approaches are used in the U.S. : First, are intensively

investigated accident crashes of which several thousand

have been collected. The advantage of this approach is

that the cases are extremely detailed with photographs

and good injury data. The most important disadvantage

is that by virtue of the changing sampling criteria and

the small sample size, the ability to generalize these

few cases to the population is restricted heavily.

I believe too much reliance has been made on this type of

data for guiding NHTSA decisions. It leads one to

situations in which too much is made of a small number of

cases.”

The critical need for better collision data to support

rulemaking can be illustrated by the passive protection provisions of Motor Vehicle Safety Standard 208. Estimates of

the cost to consumers of meeting passive protection requirements

2/, ~/ $220 to $400 per car, range from — or a gross cost of

$1.5 billion to $3 billion per year more than belt restraints

now cost. There is also significant uncertainty in the

incremental benefits that may be realized from passive

protection. Estimates range from 3,000 to 8,900 more deaths

prevented, and from 130,000 to 492,000 more injuries prevented.
Auto Collision Data

February 17, 1975

Page 14

One crucial lack of data leading to uncertainty can be pinpointed: the number of lives saved and injuries prevented by a

restraint system in frontal collisions is estimated by NHTSA from

a graph showing the percentage of injuries and deaths as a

function of “equivalent barrier test speed.”* This graph is shown

in Exhibit A (Figure 4). The “equivalent barrier test speed” is

that speed which would produce as much car damage, when the car is

driven into a rigid barrier, as the car suffered in an actual

collision.

The fatality curve of Figure 4 is based on judgment estimates

of barrier equivalent speed of 51 fatal frontal collisions by

General Motors and a small (unstated) number by Ford Motor Company;

in Figure 3 of Exhibit A the NHTSA curve is replotted for comparison

with the companies’ judgment data.

In making an estimate of the fraction of lives saved by a

restraint system, NHTSA attributes to the system a barrier

equivalent speed below which it is effective and above which it is

not effective (a conceptual convenience). On the basis of laboratory

crashes with dummy and cadaver occupants, lap belts are taken as

effective to 25 mph, lap-shoulder harnesses to 30 mph, and air-bag

6/ passive restraints to 35 mph.– The intersections of these speed

lines with the fatality curve of Exhibit A, Figure 4, then yield

NHTSA's estimate of fraction of lives saved in frontal collisions.

For example, the intrinsic effectiveness of the lap-shoulder harness

6/ in preventing fatalities in frontal collisions is thus deduced— to

be 37%, and for all collisions (of which frontals constitute 50%),

is estimated at 31%. Yet extensive field experience in Sweden shows

lap-shoulder harnesses have an overall fatality prevention effectiveness of 90%. The lap belt alone is estimated by NHTSA to have

intrinsic fatality prevention effectiveness of 20% in frontal collisions, with 22% for all collisions. Yet extensive field experience

from North Carolina indicates an overall fatality prevention effectiveness with lap belts of 75%.
—

Auto Collision Data

February 17, 1975

Page 15

0 10 20 30 40 50 60 70 80 90

EQUIVALENT BARRIER TEST SPEED (mph)

FIGURE 3 - Comparison of Fatality Distribution Data

(Frontal Collisions)

90

t

// / I

I

I

I

I

FATALITIES

I

I

I

I

EQUIVALENT BARRIER TEST SPEED

FIGURE 4- Cumulative % Fatalities Injuries within EquivaIent Test Speed Range

EXHIBIT A

Curves from NHTSA’s “Passive Protection at 50 Miles Per hour"
Auto Collision Data

February 17, 1975

Page 16

These discrepancies can be explained in three principal ways,

any of which may be correct: 1) The Swedish and North Carolina

experience is not representative of the population of U.S. car

collisions; 2) The barrier equivalent speeds up to which restraint

systems are effective are underestimated by NHTSA; or 3) The

barrier equivalent speeds at which fatalities occur were overestimated in the original material of Ford and General Motors.

All of these questions can be resolved by more and better data.

The uncertainty about these curves as a basis for rulemaking

is confirmed by National Highway Traffic Safety Administrator

James Gregory in Congressional testimony:

" . . .we have gone out on an advanced notice of proposed

rulemaking at the same time that we went out with the

passive restraint notice to say that we are moving in the

direction of a standard for occupant crash protection

at the level of 45 to 50 miles per hour. We figure when

we get there we will have pretty much attained what is

cost effective and technologically feasible in today’s

world.

“We feel, by the way, that this would still be worthwhile

doing. Yet, as we move toward that, without quantitative

data, without persuasive data, even in the public interest,

without being able to substantiate a standard we feel is

reasonable and in the public interest, the challenge would

be sufficient to provide that type of occupant protection. . .

"...The reason I have to be rather vague about this is

that most curves that have been derived by experts and

from data that have been collected qet very fuzzy when you

get much above 40 miles an hour as far as what percentage

of the fatalities occur at these particular speeds.*

* Excerpts from Dr. Gregory’s testimony before the Transportation Subcommittee of the Committee on Appropriates, House

of Representatives, 93rd Congress 2nd Session 1974, Part 3,

pp. 41 - 43 [emphasis ours].
Auto Collision Data

February 17, 1975

Page 17

...To establish crashworthiness, we need to know

what to do to an automobile and what we need to do to the

occupants from the standpoint of restraint protection

under a given crash condition. These precise data we now

lack. . .

“At the present time we cannot make a judgment with

accuracy and that makes us guess. And those guesses could

cost, unnecessarily as far as the consumer is concerned,

untold millions of dollars for protection that we may

actually not need. . ."**

The doubts the Administrator expresses about the curves at

speeds of 40 mph and above, we believe, as indicated earlier,

also should apply to speeds lower than 40 mph.

The kinds of information needed to mitigate much of the

uncertainty about the prospective incremental benefits of

passive restraints are, first, a file of representative collision

data from which it is possible to derive the incidence figures

for injury and fatality of belted occupants, in order to

establish as a baseline the capabilities for the current

belt restraints; second, results of a large-scale field experiment

to establish the relative capabilities of passive restraints;

and third, representative files of fatal and injury collisions

(involving unrestrained and restrained occupants) for which

causal severity magnitudes such as BEV have been quantitatively

established. With this information the lifesaving and injury

prevention potential of restraint systems and the speeds to which

the systems are effective can be established.

* * Excerpts from Dr. Gregory’s testimony before the Senate

Committee on Appropriations (Hearings on FY 1974 supplemental appropriations, HR 11576) 93rd Congress, first

session, part 2, pp. 1509-1510. [emphasis ours]
Auto Collision Data

February 17, 1975

page 18

Fundamental to the statistics of accidents are the

cum ulative probability distribution functions of severity

for all accidents, for injury accidents, and for fatal

accidents. These, though badly needed, are not now being

obtained from large quantities of real-life accident data.

In order to establish them, measurement and reporting of

causal severity is required.

c. LIMITATIONS OF THE CURRENT DATA SYSTEM

In a later section we address the question of collision

data requirements. The basic needs can be summarized as follows:

(1) The data should be representative of the population of

u. s. automobile crashes.

(2) The data should be gathered in sufficient quantity to be

useful, at a sufficient rate to be timely.

(3) The data should be in adequate detail and precision to

permit its analysis to determine causes of accidents,

injury and death (and the functional relationships between

these causal factors and the probabilities of accidents,

injury and death) ; and to permit answering questions that

may arise relative to traffic safety and motor vehicle

safety standard efficacy.

The inability of the current files to meet each of these

needs is expressed by several investigators.

9/ O’Day of the Highway Safety Research Institute, says:–

“A random sample is the best way of insuring represennativeness. Unfortunately, no random sample of United

States crashes exists.”
. —

Auto Collision Data

February 17, 1975

Page 19

Kidd 15/ comments:

“For too long, those concerned with accident studies

of the effects of safety standards already in force

have had to make do with either too small samples of

reasonably good data or relatively large samples of

data whose content is inadequate for the purpose. In

the first category is the data bank (and “bank” is too

grandiose a term) that has resulted from the individual

federal teams of multidisciplinary, professional

investigators. These teams can serve useful purposes in

special studies, in discovery of problems that would

otherwise go undetected and, particularly, in the area of

accident causation. By their very nature, they cannot

provide a sufficiently large data sample relevant to the

implementation of standards aimed at injury and fatality

reduction without excessive expenditure of funds.”

MDAI -- 14/ Multidisciplinary Accident Investigation— -- is

conducted by about 20 teams scattered throughout the country and

sponsored by the National Highway Traffic Safety Administration

and the Motor Vehicle Manufacturers Association. These teams

have been performing clinical in-depth studies (both on-scene and

off-scene) of selected accidents in the United States, primarily

on new cars, since 1969. The accidents selected for data collection have been strongly influenced by the specific interests of

the individual teams. Although the information gathered is accurate

and detailed, only about 6,000 cases have been investigated and

2,500 of these have entered the computerized file in the five years

since the program started. The MDAI favors accidents in which

there was injury or severe damage or in which there were large

disparities between the degree of damage and the degree of injury;

as a consequence, there is significant bias in the file. B. J.

10/ "I believe too much reliance has been made on Campbell states,—

this type of data for guiding NHTSA decision. It leads one to
Auto Collision Data

February 17, 1975

Page 20

situations in which too much is made of a small number of cases.”

According to Marie Eldridge of NHTSA, “As a system for producing

statistical information needed for supporting our safety standards,

the on-scene in-depth investigations cannot be regarded as cost

effective. The average cost per case is about $2,000. The cost

decreases to about $800 per in-depth case if the on-scene

investigation requirement is eliminated. “ Moreover, as indicated

by O’Day, “The present collection of MDAI cases is a sample of an

undefined and relatively undefinable population, thus limiting

severely the capability to draw inferences to the national accident

picture.”

A program that has long been established but only recently has

become operational is “FARS” -- the Fatal Accident Reporting

16/ System.— This system involves NHTSA collection of state data on

all fatal accidents, with recording into a uniform format that will

permit central storage, retrieval, sorting and

data plus later medical reports are included.

each occupant, each vehicle and each accident,

200,000 reports are expected to enter the file

analysis. Police

Reports are made on

so that about

yearly. Since the

file will cover all and only fatal accidents, it will be representative, but only of fatal accidents. Without supplementary

information from a sample.of all accidents whose intrinsic severity

distribution is the same as that for the fatals, inferences cannot

be drawn as to, for example, whether sobriety or use of belt

restraints affects the incidence of fatalities in crashes.

A much more representative collision data sample, structured to

14/ meet limited objectives, is being collected by NHTSA.— From five

selected regions of the country “Level II” data is being obtained on

new cars in tow-away involvements for the purpose of evaluating

active and passive restraint systems. Information is assembled from

the police report, a doctor’s report, photographs, a brief vehicle

investigation, and driver interviews. Data is collected on all
.

Auto Collision Data

February 17, 1975

Page 21

occupants, whether injured or not, but information gathered is

limited to that needed for the statistical analysis of restraint

system effectiveness. The design of the sampling process was

accomplished centrally, by NHTSA, so that the process will be

free of the biasing influence of the investigators (a serious

problem in MDAI investigations) . The cost is about $100 per crash.

The sampling plan has been designed in such a way that NHTSA

expects to be able to make national estimates based on poststratification.

NHTSA has under development a system for sampling pedestrian

and bicyclist accidents in several hundred localities. This is a

“bilevel” investigation effort in which there is a supplementary

investigation carried out by police (with the added costs borne by

NHTSA or others) to establish the nature and location of the

accidents and factors affecting visibility. It will answer questions

at the level of detail needed to determine gross behavior and countermeasures.

The States, of course, collect accident reports in great

number. The reporting thresholds vary from State to State. Within

a State, sampling may not be representative or uniform. For example,

a city with a high crime rate may devote little effort to investigating and reporting traffic accidents, while even the slightest crash

may be reported in smaller towns. Efforts by the NHTSA to use

collision data files directly from the States have proved unsuccessful primarily because of the nonuniformity of reports and the

consequent inability to properly combine, analyze and process the

information. A second problem related to the sheer volume of records

that was derived from the States.
Auto Collision Data

February 17, 1975

Page 22

On review of the information required on HS Form 214 used

in the Fatal Accident Reporting System (FARS) we observe that

certain information critically required by both rulemakers and

injury researchers is not supplied by the reporters. Specifically, provision of vehicle crush measurements that could be

converted to Equivalent Barrier Impact Speed (EBS) using the

20/ method of K. L. Campbell— would make possible construction of

the cumulative distribution function of EBS in fatality accidents,

a function needed by the rulemakers in analysis and prediction of

the effectiveness of restraint systems. Provision of information

on the vehicle interior points of impact, occupant’s height and

weight and more detail on the precise nature of injuries suffered

by injured and killed occupants would provide vital injury cause

information.

It is clear from the foregoing that there is no existing

national crash data collection program that is designed to meet

national needs. As indicated earlier, NHTSA has contracted with

the Highway Safety Research Institute of the University of

Michigan to design a national accident data sampling system based

on a probability sample. NHTSA hopes that through control of the

selection of accidents that a sample can be acquired whose

characteristics can be generalized to the national crash population.

d. MASS ACCIDENT DATA ACQUISITION

In summary, to meet data needs and to overcome the limitations

of the current national data files and collection systems, a

mass accident data acquisition system is needed. In addition,

measurement and reporting of accident causal severity is

important to the classification and analysis of accidents and
Auto Collision Data “

February 17, 1975

Page 23

often can be important to drawing credible inferences as to

the projected benefits of proposed safety standards. The

following chapter will discuss the problems of design of

the data acquisition system and of measurement of causal

severity in more detail.

The need for more and better data does not mean the

current data collection programs should be abandoned. However,

each of these programs should be reviewed as to its specific

objectives and upgraded as necessary to meet them. For

example, MDAI team investigations should conform to a

sampling plan rather than being entered into to satisfy

the personal interests of the investigators. An effort

should be made to get causal severity information and

information on injury mechanisms into FARS reports.

An extremely important characteristic of the Fatal

Accident Reporting System that might be overlooked as “just

a detail” is that it provides uniformity in the reporting

from all states, using computerized forms. This uniformity

makes it possible to combine, sort and analyze data.

Extension of this uniformity to general accident reporting

systems used by states would enormously simplify the central

collection and analysis of mass accident data, and should

be encouraged through a system of incentives.

Even with a very good mass accident data acquisition

system in being and operating, it will not be possible to

answer certain questions that were unanticipated at the time

the system was designed. Supplementary data acquisition systems

will be needed to answer such questions; the restraint system
Auto Collision Data

February 17, 1975

Page 24

collection system and the pedestrian cyclist system now operating

are examples of systems designed and needed to answer specific

questions at this time.

Mass accident data acquisition may not, by itself, answer

questions with regard to the benefit of a projected safety

standard. When the costs of such a standard are large, or

the benefits uncertain, it may be necessary to undertake a

large scale experimental program to provide the needed

answers.
—

Auto Collision Data

February 17, 1975

Page 25

Section 3, following, is necessarily quite technical.

However, much of the discussion is summarized in the

introduction to Section 4. Readers more interested in

the various alternatives for remedying deficiencies in the

existing data may wish to proceed directly to Section 4.
Auto Collision Data

February 17, 1975

page 26

3. CHARACTERISTICS OF AN ADEQUATE DATA COLLECTION PROGRAM

In Section 2 the general needs of an adequate accident data

collection program have been identified and the inadequacies of

the present system have been presented. In this section, three

characteristics of a satisfactory data collection program are

discussed: the quantities and rate of data acquisition, the

importance of an unbiased sampling plan and the measurement of

causal crush severity.

a. QUANTITIES AND RATES OF DATA COLLECTION

It is reasonable to require the data collection system to

provide timely evaluation of the effects of automobile design

changes, whether voluntary or made in compliance with official

safety standards. This suggests that the national data collection

system should be designed to gather vital information within a

single year.

15/ ~Definition of the total number of As Kidd points out,—

accident cases required annually for an adequate national data

bank can be made if (1) the questions to be asked of the system

can be identified both for the present and future; (2) the accuracy

with which the particular data elements can be measured is known or

can be appropriately examined; and (3) the statistical analysis

techniques to be employed can be agreed upon.” —-—

But rate depends also on the speed with which results must

be realized. Rapid feedback from the field is essential to the

evaluation of the effectiveness of changes, so as either to

reinforce the decision made by the designer or rulemaker or to

dissuade him from an erroneous decision.
— ——

Auto Collision Data

February 17, 1975

Page 27

In the case of general accident statistics, the population

of crashes does not represent the statistically stable ideal

(stationary time series) because of continually changing mixes

of car sizes and weights, changing rules under which cars are

operated (for example, the Federal 55 mph speed limit) , changes

in the quality and extent of highways, variation from season to

season and year to year in total miles driven, and modifications

to vehicle designs, both voluntary and in compliance with safety

standards.

The allowable lag in production of statistics, based on the

foregoing considerations, appears to be about one year. This, in

turn, suggests that a sufficient body of data should be gathered

within one year to detect differences in injury incidence as a

result of actions on the part of the government or the carmakers.

In the following paragraphs we will estimate what this may

mean in terms of the number of reports required per year and, if

causal severity were to be obtained through the use of crash

recorders, the number of crash recorder installations that would

be needed. Some less important data might be acquired over longer

periods, lessening the amount of data required annually.

We have previously indicated that one objective of collision

data gathering is the construction of cumulative distribution

functions for severity for all accidents, all injury accidents, and

all fatal accidents. The first of these is needed to provide

reference or baseline statistical information from which other

important statistics may be derived; the second and third are

needed to validate the rationale used in rulemaking. A

statistical technique* permits prediction of the number of

------------------------------

* The Kolmogoroff-Smirnov test; see, for example, “Nonparametric Statistical Inference.” J.D. Gibbons,

McGraw Hill 1971.
Auto Collision Data

February 17, 1975

page 28

observations in a random sample that would be required to

construct these distribution functions with a confidence of

x percent that the function derived from the sample will be

within Y percent of the true distribution. Table 1 tabulates

the number of samples required for several levels of

confidence and accuracy.

Table 1

Number of Observations Required

To Construct Cumulative Distribution Functions

Deviation

From

“Truth”

1%

2%

3%

4%

5%

8%

10%

Confidence Level

80% 90% 95%

11,449 14,884 18,496

2,862 3,721 4,624

1,272 1,653 2,055

716 913 1,156

458 595 740

179 233 289

115 150 185

The table indicates the number of reports that would be

required to construct distribution functions of severity if

severity could be measured for each year.
—

Auto Collision Data

February 17, 1975

Page 29

The tabulated numbers represent also the number of reports

needed in a segregated category to construct a severity distribution function for that category. Taking a typically acceptable

statistical level of 95% confidence, 5% accuracy, 740 fatality

reports would be required to construct a severity distribution

function for fatalities; 740 injury reports would be required to

construct severity distribution function for injury cases.

Suppose it were desired to examine the distribution function for

car weights in injury cases, independent of all other factors;

again, 740 reports would be required in which weight was stated.

The need for a large number of annual reports arises when a

particular set of events to be examined has low probability of

occurrence in the sample. Suppose, for example, one wishes to

determine the distribution of car weight in rollover injury

accidents for two categories of occupants: belted and unbelted,

740 reports in each of the two categories would be required.

Injury accidents constitute 33% of reportable accidents, and the

3/ probability that an injury accident was a rollover – is about 8%.

Perhaps 25% of those injured wore belts. Thus 0.67% of reportable

accidents were rollover-injury-belted, and to find a sample of 740,

an aggregate of 111,000 reports in the ‘reportable accident”

category would be required. (This same set of reports would provide

more than enough unbelted-rollover-injury events.) If only injury

accidents were reported, a sample of 37,000 reports would suffice.

If the same analysis were to be done for fatal rollover accidents

drawn from a mass accident file, the file would have to number

3,500,000 to find 740 fatal-rollover-belted events. The reason for

the much larger data file in this case is that there are far fewer

fatalities than injuries.

* 0.25 X 0.08 X 0.333 = 0.0067.
Auto Collision Data

February 17, 1975

Page 30

Analysis of infrequent events requires many input reports.

But the fact that events are infrequent does not make them

unimportant. The best example of this is traffic fatalities, which,

though infrequent, cost society almost as much as automobile

injuries and

Suppose

implemented,

95%, that it

damage combined.

that a new restraint system modification were

and one wished to confirm, to a confidence level of

reduced the incidence of occupant fatalities in the

population of all accidents by 10% over the old restraint system.*

Assuming the old system had a (perfectly known) fatality rate (when

used) of 0.06%. We are seeking to verify that the new restraint

system gives a fatality rate of 0.054% or less. The use rate on

the new restraint system is expected to be 50%. An upper bound on

the number of accident reports required to determine the fatality

incidence to the desired accuracy is found to be 768,000. If this

were to be accomplished in the first year Of the new installation,

reports would be needed on about 30% of all accident involvements

of new U.S. automobiles. Clearly, reports on fatal accidents alone

would not be useful, as fatality incidence could not be determined.

The foregoing calculation makes use of an expression for the

number of samples n required to determine with accuracy r a

proportion p in the population from which the sample is drawn,

namely:

n =

p (1-p)

cJClearly, if the same question were restricted to side impact

accidents a sample of 768,000 side impact accidents would be

needed, but since side impacts constitute 1/6 of all accidents and

were drawn from a sample of all accidents, that sample would have

to number 4.6 million.

------------------------------

* A practical example of the kind of question NHTSA and

safety researchers seek answers to.
.

Auto Collision Data

February 17, 1975

Page 31

One can now see, from the examples given, the extent to which

numbers of reports required depend on the questions asked. Efficient

sampling to minimize the number of samples requires a basic set of

questions to provide baseline statistics with supplementary surveys

to obtain the answers to specific questions.

Based on the previous examples of questions that might be asked

of an accident file, we believe that 500,000 to 1,000,000 cases per

year, collected in accordance with a carefully designed sampling plan,

is needed by NHTSA and others.

We determine now the number of crash recorders that would be

needed to determine accident severity distributions if recorders were

the chosen technique to measure accident severity. The number of

recorders required depends on the probability occurrence of the type

of collision. About 7.5% of all cars are involved in reportable

accidents, 2.5% in injury accidents, and 0.04% in occupant-death

accidents each year.

Table 2 indicates the number of recorders required to get the

needed data each year to construct severity distribution function

curves to 5% accuracy (5% corresponds to approximately 2 mph in

estimate of barrier equivalent impact speed) . The figures in the

column headings are the probabilities that a recorder equipped car

will be involved in an accident of the type indicated; 100%

recovery of recorder data is assumed. 30% of involvements are

considered to be of “reportable” severity: that is, that the

damage to the vehicle is of sufficient extent, or that there is an

injury, either of which would require reporting the accident to

police.
Auto Collision Data

February 17, 1975

Page 32

Table 2

Number of Recorders Required to Secure in One Year

Data Needed to Construct Severity Distribution Functions

to 5% Accuracy

Confidence (

Level

8 0 %

90%

95%

Accidents Above

a “Reportable”

Severity Level

P = 0.075

6107

7933

9867

Injury

Accidents of

All Types

P = 0.025

18,320

23,800

29,600

Fatal -to-Occupant

Accidents of All

Types

P

= 0.0004

1,145,000

1,487,500

1,850,000

If it were further required to construct these distribution

functions for smaller classes of accidents (frontal, side, rear,

rollover) the number of recorders required, for 90% confidence

and an accuracy of 5%, would be as shown in Table 3. (Based on

accident type probabilities given in references 3 and 6.)

Table 3

Number of Recorders Required to Secure in One Year

Data Needed to Construct Severity Distribution Functions

With 90% Confidence of 5% Accuracy

Accidents Above

a “Reportable”

Severity Level

Frontal 16,190

Side 46,665

Rear 27,355

Rollover 198,000

Injury

Accidents

64,324

58,048

170,000

297,500

Fatal

Accidents

2,917,000

5,313,000

29,750,000

9 ,297,000

I
Auto Collision Data

February 17, 1975

Page 33

As the cell size becomes smaller -- that is, as the data is

subdivided into more and more classes of interest -- the number

of reports needed in each cell for the construction of the

particular distribution function of severity remains the same;

but the number of recorders required to assure that required

number of reports in each cell increases rapidly. Clearly, either

a very large number of recorders would need to be installed in

the U.S. automobile fleet, perhaps one in each car, or alternate

methods of obtaining a measure of severity, such as measuring

structural deformation of the automobile, should be used.

If a very cheap (say, $2) crash recorder does not become

available, then it is clear that crash recorders become

impractical because of costs as a means of measuring severity

for mass accident data files, which are needed to evaluate events

of low probability yet events of great importance.

b. THE NEED FOR DEFINITION, MEASUREMENT AND

REPORTING OF CAUSAL CRASH SEVERITY

Throughout earlier sections of this report, reference has

been made to accident severity. It is important to note that

what is meant is intrinsic or causal severity, as opposed to the

severity of the outcome of crash, such as the degree of injury

or damage. As indicated earlier, selection of a sample based on

outcome inherently biases the sample and masks the effects of

design changes. What is needed, instead, is a bank of data that

will permit determining, for a given causal severity or range of

causal severities, the outcome as a function of other factors --

car weight, occupant age, passenger compartment design, etc.
—

Auto Collision Data

February 17, 1975

Page 34

For example, in establishing bumper standards,

useful to know, first, the probability distribution

crash severity and second, the relationship between

car damage and the severity of the collision in the

it would be

for causal

costs to repair

absence of

damage limiting bumpers. From this information could then be

predicted the gross benefits of new bumpers that prevented damage

in accidents up to a specified severity level.

In determining the efficacy of an existing motor vehicle safety

standard for occupant protection, it is important to be able to

establish how the probability of injury (or degree of injury) is

affected by meeting the standard. This implies a need to develop

a file of crash reports whose inclusion is based on causal severity

level (as opposed to outcome) , so that the incidence of injuries

can be compared for cars that meet the standard and those that do

not. Stratification of the data by causal severity levels would

make it possible to draw inferences about benefit of the standard

as a function of severity. Without the severity measure, the

levels of exposure of uninjured occupants cannot be determined, and

the basis for finding and comparing injury incidence is lacking.

—.

It has been pointed out in an earlier section that there are

doubts about the validity of the NHTSA curves of the cumulative

distribution functions of barrier equivalent impact speed (BEV or

EBS) for injury accidents and fatality accidents. Validating

these curves from real-life accident data would require measurement and reporting of the causal severity of fatal and injury

accidents.

The measurement and reporting of causal severity in crashes

provides a relatively unbiased method of screening crashes for

investigation and introduction into a file. Once the severity

distribution function for all crashes is established with sufficient
Auto Collision Data

February 17, 1975

Page 35

accuracy, reports can be identified by severity level, and only the

number of reports needed in each stratum can be selected for

admission to the file. Knowledge of the severity distribution

functions both for the population and for the file permits analysis

of the constrained file and extending inferences to the universe of

crashes. At the same time, the size of the file can be reduced by

preventing the entry of ‘the voluminous reports of low severity

crashes whose frequency is high.

10/ feels that a crucial need in the field of B. J. Campbell—

crash injury is the means to forge a meaningful link between

laboratory test crash data and events as they occur in the field:

“In the staged crashes in the laboratory, telemetric

procedures are used for recording data and one can

justify in considerable detail the physical system in

which the crash occurs -- the ‘9’ -forces, the rate of

onset, delta ‘v’ etc. But when one is forced to use

nonhuman subjects then one is left in the situation of

knowing a great deal about the physics of the crash but

knowing little of the actual injuries that might have

occured in such a crash. On the other hand, in real world

automobile crashes one can learn about the actual outcomes

in terms of survival and injuries, but the input variables

mentioned before are unknown.

—.-

“The need to link these two systems is apparent.

Engineers who design protective systems need to know

about stopping distances, forces, decelerations, etc.

But knowing these things is of too little help unless

one has a way to relate them to real world injuries.”

Clearly, a measure of real-world crash severity would help

provide such a link.
Auto Collision Data

February 17, 1975

Page 36

The question remains as to what constitutes a proper causal

severity measure, or “Vehicle Crash Severity Index (VCSI)"19,22

This question is independent, of course, of what parameters are

being or can be measured, such as vehicle deformation, acceleration

time history, speed at impact, etc.

The severity measure that has been used in tests, some crash

reports from the field, and in motor vehicle safety standards is

Barrier Equivalent Impact Velocity (BEV or EBS). It is of

interest to examine whether this is a reasonable measure of causal

severity, both as regards occupant injury and vehicle damage.

What injures unrestrained and loosely restrained occupants is

the so-called “second collision” of the occupant with the interior

of the automobile, such as the windshield, dashboard, B-pillar, etc.,

or with the restraining belts or air bag. The speed with which an

occupant impacts an interior element has fair correlation with the

injuries he suffers. The speed of impact is determined by the

average car acceleration component in the direction from the object

to the occupant and the distance between the two:

V=’ 2 a d

The commonly used head injury criterion is:

HIC =

2.5
Auto Collision Data

February 17, 1975

Page 37

or, in terms of car average acceleration during the crash, is:

Thus, we observe that the criterion for head injury severity

increases with car acceleration during the crash interval, but at

a slightly greater rate.

If the occupant is tightly restrained, he is subjected to

the same acceleration as the occupant compartment of the

automobile. The forces he experiences are in proportion to this

acceleration and the weight of his own body. It has been

23/ that human tolerance limits can be determined by investigators—

best expressed in terms of the acceleration to which a person is

subjected during the crash interval. It is important to note

that rapid variations of acceleration with time are not felt by

the unrestrained occupant in crashes in which his motion has a

forward component relative to the car, as he is in “free flight”

until he impacts the interior. The fully restrained occupant

feels these changes (called “jerk”) but there is no evidence to

indicate that they inflict more than minor punishment; the

damage to the restrained occupant appears to result from the

average level of acceleration he is subjected to during the crash.

Thus we observe that the two most important measures of

injury tolerance can be related directly to vehicle acceleration

during the crash. The next question is whether and how barrier

impact velocity is related to this acceleration.
—

Auto Collision Data

February 17, 1975

Page 38

Running a car into a barrier causes deformation of the car

(“crush”) . It has been found in the laboratory that there is a

linear relationship observed between impact speed and residual

3/ crush. The average acceleration during the crash– is:

where VO is the barrier impact speed and k is a measure of the

“stiffness” of the car. Thus we observe that the car acceleration

is directly proportional to the barrier impact speed, but also t.

the stiffness, which is higher in small cars than it is in full size

vehicles.

We conclude, therefore, that barrier impact speed is a

reasonable indicator of injury-related causal severity provided

that car stiffness is taken into account.

K. 20/ L. Campbell— has evolved a sophisticated approach to

relating vehicle damage to collision severity. In this approach

the dynamic force-deflection characteristics are used to estimate

the energy absorbed in plastic deformation of the vehicle. A

linear force-deflection characteristic is the simplest (but not

necessarily the most accurate) model leading to the observed

linear relationship between impact speed and crush distance,

and is used by Campbell. The energy can then be expressed as

an equivalent barrier speed (EBS or BEV). The approach has been

partly validated for frontal impacts in angle and offset barrier

tests: The BEV estimates based on vehicle damage differed from

the true impact speeds in the angle barrier case, over impact

speeds ranging from 18 to 31 mph, by an average of -0.35 mph, with

a standard deviation of 2.85 mph; and in the offset barrier case,

over a narrow range of impact speeds around 30 mph, by an average

of -0.01 mph, with a standard deviation of 1.64 mph. The input
.

Auto Collision Data

February 17, 1975

Page 39

information items required to make the estimate were the crush

coefficients as determined from pure frontal barrier tests for each

of the various automobiles, together with the actual detailed crush

measurements in the test impacts. K. L. Campbell believes that the

technique can be extended to side and rear impacts; such an extension

would, of course, require determination of side and rear crush

coefficients. The crush coefficients, as defined by K. L. Campbell,

are the slope and intercept of the curve of impact speed as a

function of crush distance. The slope is identical to the reciprocal

of the “stiffness” constant we used in the previous paragraphs.

A. B. Volvo employed a series of eleven full-scale frontal

24/ barrier, car-to-car and car-to-pole impact tests— to obtain

data on crush characteristics of the Volvo model 140 automobile.

This information was used in conjunction with detailed measurements of deformation incurred in real-life impacts to estimate

barrier equivalent speeds for 128 collisions.

In uncomplicated collisions, we believe that similarity

between real-life collision-caused vehicle deformation and that

produced in a laboratory staged crash having the same point and

direction of impact, implies correspondence between the forces

and rates of application. Thus measurements of vehicle deformation can be analyzed, compared with the outcome of staged crashes,

and used to estimate barrier equivalent impact speed. However,

it is not possible to say that equivalence of deformation always

implies equivalent dynamic forces.

Average acceleration during the crash interval appears to be

a reasonable measure of causal crash severity. There are several

methods by which it can be measured:
Auto Collision Data

February 17, 1975

Page 40

(1) By a crash recorder that records acceleration time history

(later to be time-averaged over the crash interval to get

a severity measure) absent a cheap crash recoder, that

directly averages accelerations over the crash interval.

The limitation of this approach relates to the large number

of recorders required for mass accident files designed to

illuminate rare events and the substantial expense associated

therefore with this technique. For special measurements such

as severity distribution functions, the number of recorders

required becomes much smaller, and then this technique of

severity measurement becomes appropriate.

(2) By measurement of vehicle deformation (the vehicle is its own

crash recorder) and conversion to barrier equivalent speed or

average acceleration. The limitation of this approach relates

to the limited availability of calibrated deformation information derived from laboratory crashes. Another limitation for

mass accident files is the limited ability of police, at the

scene of an accident, to judge deformation either using the

calibrated crash deformation information, or some other

technique, in a consistent reliable manner.

(3) 15/ By computer reconstruction of the collision— (SMAC) in an

iterative simulation process that is driven to match the

reconstructed accident to real–life observations of skid

marks, vehicle positions, etc. Momentum changes, in

conjunction with known vehicle stiffness characteristics,

can be used to estimate crash accelerations. The limitation

of this technique is that it requires trained investigators

who can estimate the initial conditions of the crash so as to

initiate the computer simulation. If the simulation does not

converge to the actual disposition of vehicles after the crash,

the estimated initial conditions must be revised.
Auto Collision Data

February 17, 1975

Page 41

It must be recognized that the crash severity index is a

vector, and has magnitude and direction. Two linear accelerometers are necessary to measure its components in the horizontal

plane. A third (vertical) component is measured with

experimental crash recorders, but does not appear to be very useful.

A problem arises in using vehicle deformation to measure

damage-related crash severity; obviously, the cause and the

outcome are related. If the outcome is defined as physical

deformation, the relationship is one to one. If the outcome is

defined as cost to repair, the cause and the outcome are not

identical. There is also a flaw in the use of acceleration during

the crash interval as a measure of causal severity: if vehicle

exteriors were softened, so that average collision accelerations

were lowered, average severity would decrease even if the average

impact speeds remained the same. So the injury mitigating effects

of vehicle softening would be obscured in the collected data.

Similarly, where vehicle crush is used to determine severity, if

vehicles are designed using resilient materials that do not

permanently deform, the average severity would decline despite

unchanged average impact speed.

Thus we believe it is important that the National Highway Traffic

Safety Administration undertake the job of defining causal crash

severity in the most useful and realistic way.

There are several measures of severity currently in use that

are quite crude and inaccurate and should be supplanted by better

methods.
Auto Collision Data

February 17, 1975

page 42

The deformation extent, a quantity somewhat related to

severity, is often reported in Level II (greater depth than the

police report) and Level III (in-depth) investigations. The

deformation extent is one element of the collision deformation

classification (CDC) code assigned in accordance with the Society

of Automotive Engineers recommended practice SAE J224a. However,

SAE recommended practice J224a warns “The extent number should not

be used as a tool for determining severity or energy required to

duplicate the damage. For vehicles of the same basic type, it

does serve as a tool for gathering together vehicles which have

similar damage characteristics. “

Some reports give the full CDC (sometimes known as “VDI”) code,*

which describes the direction of force, general area of deformation,

specific horizontal area, specific vertical area, type of damage

distribution, and extent. The Fatal Accident Reporting System reports

only impact points and an abbreviated damage extent number.

Pollee reports often include estimates of traveling speed

prior to impact, a very poor indication of severity because of

the uncertainty of the effects of braking just prior to impact.

Sometimes “impact speed” is estimated and reported; again this

is a very dubious measure of severity because it is neither

uniformly defined nor readily estimated. It may be, depending on

the investigator, either speed relative to the ground at the

instant of impact of speed relative to the struck or striking

21/ object. Ford Motor Company—, in an analysis of the differences

between investigators’ reports of impact speed and the speed

------------------------- -- -

* See, for example, reports on crash recorder equipped cars,

reference 19.
Auto Collision Data

February 17, 1975

Page 43

changes indicated by crash recorders, found differences as great

as 40 mph and a standard deviation of 11.9 mph in 20 collisions

involving crash recorder equipped cars. The average was a speed

overestimate of 14.7 mph by the investigators.

MDAI teams and other in-depth investigators may report their

judgment estimates of equivalent barrier speed (EBS) based on

their background of understanding of the relationship between EBS

and vehicle deformation in laboratory crashes.

To summarize,

(1) Average acceleration during the crash interval is a reasonable

measure of the intensity component of a causal crash severity

index, but has some deficiencies as such.

(2) NHTSA should, with the approval of the accident research and

statistical community, settle on and begin to use an acceptable

definition of crash severity index.

(3) If average acceleration during the crash interval is the

appropriate measure, there are several ways of measuring or

estimating it with reasonable accuracy.

(4) Several indices of severity currently in use are so erroneous,

misleading, or ill-defined, as to be valueless, and should be

either upgraded or discarded.
Auto Collision Data

February 17, 1975

Page 44

c. THE CRITICAL IMPORTANCE OF AN UNBIASED, RELEVANT, AND

ADEQUATE SAMPLING PLAN THAT IS APPROVED BY EXPERTS

In order to meet requirements for collision data collection,

it is necessary to generate a plan for sampling and to implement

it. The plan should call for collection of a representative

sample of crash data in quantity sufficient to be useful at a

rate sufficient that the data is timely, and in enough detail and

with enough accuracy to permit answering outstanding essential

questions.

Thus there are three separable issues:

(1) The methods of assuring that the sample

is representative.

(2) The quantities and rates of data gathering.

(3) The information content, detail, and

accuracy of reporting.

The problem of securing a representative sample is a difficult

and subtle one. 16/ To quote Versace (Ford Motor Company)— on the

need for scientific sampling:

"Not only is an increased quantity of data required but

the sampling of the accident universe must be by sophisticated protocol. The last of the three reasons given above

implies the need for a disciplined approach to the data, to

avoid ending up with data which are biased in the factors

underlying them. That requires a scientific approach to

data collection, not just pouring more dollars into it and
—.

.—

Auto Collision Data

February 17, 1975

Page 45

cranking up the administrative machine to get a bigger

program going but doing it in the same old way, Data

gathering programs must be designed by the same people

as will design the analyses that will be applied to the

data. No less expertise than the Census Bureau applies,

or the Gallup Poll, will suffice. Fortunately,NHTSA has

been bringing in very competent people of late, people

who know that a data collection scheme must be designed

from the start with the method of analysis of the

resulting data a key determiner of how the data should be

gathered.”

The importance of representativeness of the sample is hard

8/, 9. to overstate.– The sample should be representative of the

entire population of automobile collisions or have an accurately

known relationship to that population. If the sample is selected

in some way -- that is to say, if the sample is biased --

inferences drawn from the sample may be faulty. For example,

consider a sample in which only injury accidents are represented.

If, say, wearing’ belts reduces the risk of injury 50%, belted

occupants will be underrepresented by 50% in the sample. Two

incorrect inferences might be drawn by a naive observer:

1) occupants in accidents don’t wear their belts; 2) most of the

belted occupants in the sample were injured; obviously belts are

not very effective.

Despite the importance of avoiding sample bias, much of the

material in the existing national files is heavily biased and,

until recently, little thought was given to rectifying this

deficiency. NHTSA has contracted with the Highway Safety Research

Institute of the University of Michigan to evolve a national crash

data sampling plan which, presumably, will be based on sound

statistical principles.
Auto Collision Data

February 17, 1975

Page 46

The questions to be asked of the data file determine the

sampling plan: that is, the selection of regions to be sampled

and, within those regions, the collisions on which information

is to be collected; the quantity and rate of acquisition of case

reports; and the information -- kind and reporting precision --

required in each report.

Examples of such questions are:

(1)

(2)

(3)

(4)

How effective have the requirements of MVSS 206 (which

specifies crash load requirements on locks, latches, and

hinge systems) been in preventing occupant ejections? In

preventing occupant injury? Are there significant

differences in capability between makes and models of

automobiles?

How effective are belt restraint systems (specified by

MVSS 208) in preventing injury and death? How does the

effectiveness vary with accident severity? Car weight?

Occupant age?

At what collision severity level should the bumper system

prevent damage to the automobile? Should the requirements

be different for front and rear bumpers? For different car

sizes and weights?

HOW important is car visibility in preventing collisions?

Are the requirements of MVSS 108 (for lighting) effective in

satisfying the needs for nighttime visibility?
(5) What are the factors in passenger compartment design

that are of significance in contributing to or preventing

occupant injury? To what extent do the characteristics of

the occupant himself influence the injury picture? What

are the interactions of these factors?

As an example, the last question suggests a number of items

of information required for inclusion in reported crash data.

10/ According to Lawrence Patrick of Wayne State University—,

“complete injury data must be included in the accident data.

Sex, age, weight, height, and general physical condition are all

important factors . . . The type and degree of injury of each

occupant including the minor bruises and abrasions and going

through the severe bone and soft tissue damage are required. It

is important to have complete data on the restraint systems used

and the interior components of the vehicle that caused the injury.”

Also needed, according to Professor Patrick, are impact velocity

(as a measure of severity) and direction, location of the impact,

seating positions of the occupants, vehicle rigidity, and vehicle

interior design.

The design of the sampling plan is critical to the utility of

the bank of data that will be acquired through the sampling

process. If the reported information is inadequate, crucial

questions that one wishes to ask of the file will be unanswerable.

If the sample fails to represent the U.S. crash universe, or

contains biases, the answers to questions may be quite wrong. And

if the quantities of cases on which answers are based are inadequate,

the confidence one can assign to the answers is low.

Thus we believe that the National Highway Traffic Safety

Administration should proceed urgently with the development of a

sampling plan (hopefully, the contract with HSRI will provide the

necessary result; if not, it should be augmented).
Auto Collision Data

February 17, 1975

Page 48

When completed, but before the plan is implemented, it

should be submitted to, reviewed by and approved by a jury of

nationally known experts representing the disciplines of

accident and injury research, motor vehicle design, rulemaking,

and statistical sampling and analysis.
—

Auto Collision Data

February 17, 1975

Page 49

4. ALTERNATIVES FOR AN ADEQUATE DATA ACQUISITION PROGRAM —

The elements of an adequate data acquisition program have

been previously described as comprising a mass data acquisition

system with acceptable crash severity capability, a precision

crash dynamics measurement system and special investigatory procedures such as multidisciplinary accident investigating teams

(MDAI) and fatal accident reports (FAR).

Section 3 has described the quantitative requirements for

mass accident data collection. It has been indicated that approximately 500,000 to 1,000,000 accident reports per year are needed

to obtain early warning of motor vehicle hazards and to obtain

confirmation of the effectiveness of various safety programs

in a timely way to a reasonable level of significance. The exact

number of annual accident reports needed depends on the level of

detail of the desired results, the frequency of the event being

investigated, the desired accuracy and confidence level of the

information being obtained and the time by which the information

is desired.

For example, if one wishes to determine the fatality rate

in rollovers of belted drivers in one year to an accuracy so

that the standard deviation is 30% of the mean, 130,000 accident

reports would be needed. However, if one wished to determine

the probability distribution function of car weight in cases where

belted drivers are killed in rollovers to an accuracy of 5% with

a confidence of 95%, 3,500,000 accident reports would be needed.

The kind of data needed for this mass acquisition system is

generally agreed to be a causal severity index, vehicle identification number, road and visibility data, injury scale, restraint
Auto Collision Data

February 17, 1975

Page 50

system and usage, driver and occupant descriptions and seating

positions, with many other items required, perhaps on a

special survey basis, to answer specific questions.

There are a number of ways to obtain a causal severity

index. If a cheap ($2) two axis crash recorder can be developed

--and there are some concepts worthy of exploration--their

installation on production cars is justified. This possibility

is more fully discussed later in this section.

In the absence of a cheap crash recorder, vehicle deformation should be used as a causal severity index. There are at

least two major approaches, one following the lead of

Professor B.J. Campbell at the University of North Carolina,

and the other following the approach of Professor Lawrence

Patrick at Wayne State University, the Biomechanics Research

Center and practiced in a recent Volvo-Wayne State University

study.24/

The State of North Carolina uses police reports of severity

reported by the TAD system.* Police training has evidently been

7/ although the data sufficiently good to obtain useful reports—

base has been small and the severity reporting system quite

simple. 7/ The disadvantage of this approach is summarized by Griffin:–

------------------------------ -

* A police officer using the TAD system rates severity on a

1 to 7 scale by matching the damaged vehicle with a manual

of photographs of typical accidents.
—

Auto Collision Data

February 17, 1975

Page 51

“Rural accidents tend to be more severe than urban

accidents, therefore, police level data for a given

state must be generalized with caution, even within

that state.

“It is not simple to generalize police level data from

one state to other states. States differ with respect

to traffic density, number of interstate highways, and

weather conditions. All of these factors interact with

accident types and configurations, and thereby affect the

benefits to be derived from a safety device.

“Finally, police level data are not recorded in detail.

Levels of vehicle damage and occupant injury are evaluated

by an officer who may be trying simultaneously to summon

medical aid, direct traffic, and determine whether or not a

law has been broken. Under these circumstances, the

data yielded by these investigators is very good, but

necessarily the collection of data should not be

considered the officer’s area of expertise or his major

area of responsibility.”

10/ fee1s the cost of improved police Professor Campbell—

reporting could be nominal and that it would be important to

extend the North Carolina system, or some improvement of it, to

a number of states that might together provide 600,000 - 1,000,000

reports which would be less biased than those from rural North

Carolina alone.

It is difficult to accurately determine the cost of this

system, but $3-10 per report is approximately correct, or a total

of $10 million for one million reports. However, there is some

question of the adequacy of police data for many needs.
—

Auto Collision Data

February 17, 1975

Page 52

professor Patrick’s approach to the recent Volvo experiment—24/

might be utilized to improve the reporting of causal severity by

police. Staged crashes of major U.S. models, front, side and rear

into poles, barriers and cars at three speeds could be used to

obtain calibrated deformation data. The one-time cost of such a

program is estimated* to be $3-5 million. There are a number of

possible ways to use these data. Police could be trained to photograph** the damaged vehicle from a few aspects after having placed

appropriate identification placards and scales on the damaged

vehicle. The film could be subsequently processed at various centers

to derive the severity data by analysis Of the photographs and by

comparison with the calibrated deformation data. The total accident

report including police and medical data, if any, could be

assembled at the photographic analysis center.

Alternatively, it might be possible to train police equipped

with appropriate templates to measure the collision deformation in

conformance with a handbook based on the calibrated deformation

data from the staged crashes. Appropriate supplies, compensation

and incentive would have to be provided to local police. A cost

of $10-2O per accident report might be sustained by more detailed

analysis of this reporting system. Therefore this type of mass

accident data system might cost a total of $25-30 million for the

first year including non-recurring capital as well as operating

costs.

------------------------------ -

* Conversations with Professor Patrick.

* * Mr. John Garrett of Calspan reports some success in Western

N. Y. comparing estimates of severity from police photographs

with estimates of professional accident investigation teams.
Auto Collision Data

February 17, 1975

Page 53

In Section 2 there was also described the need for some

precision reference data. This need was stressed by almost every

1/, 10, 11, 13, 14/. participant in the Workshop.– — — — — In particular

sume 10,000 sophisticated recorders with an accuracy of 1-2 mph*,

are needed to obtain in one year’s time a representation of the

probability distribution of severity of accidents (above the police

reporting threshold) with severity (barrier impact speed), to an

accuracy of 5% and at a confidence level of 95%. If this representation of the distribution of severity were limited to frontals only,

the confidence level would be only 80% with an accuracy of 5%.

Alternatively, 20,000 recorders could be used to obtain this

distribution for frontal collisions to an accuracy of 5% at a

confidence level of 95%. The cost of sophisticated crash

recorders in these quantities is approximately $200. Therefore

the total cost of this basic program is between $2 and $4 million

plus the cost of data retrieval and analysis.

The cost per accident report from the sophisticated crash

recorder** would be approximately $2,000 the first year, declining

to $1,000 over the first two years, $500 over the first four

years, $200 over the first ten years. This is the normal

characteristic of the flow of benefits over a period of time from

an initial capital expense.

------------------------------ -

* This corresponds to a 3.8 - 7.6% change in the cumulative

distribution of fatalities or an annual dollar cost

equivalence of approximately $250-500 million in estimating

the effectiveness of occupant restraint systems.

* * Described later in this section.
Auto Collision Data

February 17, 1975

Page 54

The SMAC system of computer-aided accident reconstruction

could also be used to obtain precision reference data, and is

competitive with the sophisticated crash recorder. It is our

opinion that the SMAC system, while extremely clever and promising,

has not completed its development cycle, and must be operated by

full time professionals. These might be specially trained police.

However, some means would have to be found to compensate state and

city police for performing NHTSA work. If a SMAC van is to operate

around the clock, a crew of eight per vehicle would be required.

If as many as 100,000 accidents were to be investigated per year

with 500 vans, a total crew of approximately 4000 men would be

required at an annual cost of $60 million. Thus, the manpower cost

seems to limit the SMAC system to obtaining relatively small numbers

of reports, say 10,000 per year or lower. The SMAC system like the

sophisticated crash recorder, seems most useful for special data

gathering programs requiring precision severity data. If 2500–5000

accidents are to be investigated per year, perhaps 15–20 vans would

be required at a total manpower cost of $1.8 - 2.4 million plus the

cost of equipped vans and processing centers, or roughly $5OO per

case.

These costs should be compared to the current costs of MDAI

investigations at $2000 per case on scene and $800 per case off

scene , FAR reports at $15 per case, Level II reports at $100 per

report.

Some safety devices, particularly those with uncertain

performance and high cost to the consumer, could be subjected to a

field test prior to general introduction. Some Federal agencies,

The Food and Drug Administration, for example, do require extensive

tests of products before general use. These tests, if properly

designed and monitored, could yield invaluable data on the benefits

from such devices.
Auto Collision Data

February 17, 1975

Page 55

However, a safety feature like the 5mph bumper or passive

restraints can probably not be sold on a trial basis depending

on market forces alone. Therefore, Federal sponsorship would be

necessary to design the field trial, pay the cost of installation

and monitor the results. This process would be expensive but, when

viewed against huge consumer costs, may be worthwhile.

Such a test has been suggested for passive restraint systems

by the National Motor Vehicle Safety Advisory Council, a body

advisory to the Secretary of Transportation, by a Resolution

adopted by an 11 - 5 vote on November 19, 1974.*

It is the feeling of a number of both the academic and

automotive participants in the Workshop, and the authors of this

report, that a field trial of 100,000 - 200,000 passive restraint

systems is necessary.

The size of the field trial of passive restraints arises from

the following considerations. If one assumes that the passive

restraint is effective in reducing fatalities by 50%, then it would

require three years of field trial of 200,000 equipped cars to

determine the probability density of severity given a fatality to

an accuracy of 10% with 80% confidence. On the other hand, if one

wished to determine whether the fatality rate in all passive restraint

equipped cars had decreased by 50% to an accuracy of 20%, 125,000

installations would be required to obtain an answer in one year.

If on the other hand, one wished to determine the performance to

the same accuracy in light cars as compared to heavy cars, one

would have to wait two years, assuming the 125,000 car sample was

split equally between heavy and light cars.

.

----------------------------- -

* See Appendix L.
Auto Collision Data

February 17, 1975

Page 56

For this field trial to be unbiased, these systems would

have to be installed in small and large vehicles in representative

parts of the country with a representative set of drivers. Since

market forces cannot be depended upon to provide this, it is

probably in order for the Federal mandator of the proposed regulation

to support the trial. The cost of such a program could be $30 - $60

million.

In summary, an extensive mass accident data system of one

million reports annually may cost

(1)

(2)

(3)

$3-10 million annually using the North Carolina approach of

upgrading police reporting, plus the cost of improvements in

severity estimation;

$10-20 million annually using the Wayne State - Volvo approach

to obtaining accident severity, PIUS the costs of reporting

factors other than severity, plus a one-time cost of $5

million for calibrated vehicle crash data and other capital

expenditures:

$10 million annually to obtain severity information alone if

a cheap ($2) crash recorder could be developed and installed

on 50% of all new production. One would have to add. to this

cost the cost of collecting the records, analyzing the

data and coalescing this information with other accident

information in a mass data file.
Auto Collision Data

Page 57

These several approaches are potentially mutually supportive

rather than competitive. There is presently no such thing as a

cheap recorder, so one cannot depend on it for severity data.

Should one be developed, it would be extremely useful for mass

accident data. A serious effort toward this objective should be

undertaken. If the Wayne State - Volvo approach to obtaining

accident severity could be developed to apply to the U. S.

problem, then it might be used in conjunction with the North

Carolina approach as a better method of estimating severity.

A needed tool for precision research on the crash dynamics

of a few thousand accidents annually may be obtained by either

SMAC simulation or precision crash recorders.

(1) $2-4 million first cost for 10,000 to 20,000 sophisticated

crash recorders plus the cost of the facilities and personnel

needed to analyze and correlate the data produced as an

annual expense.

(2) $2-2.5 million annually for personnel on vans plus the vans

themselves and analytical equipment.

It would seem possible to put emphasis on one or another of

these programs. In doing this NHTSA should take into account

the somewhat higher first costs of the crash recorder program as

compared to the somewhat higher annual operating costs of the SMAC

program. Obviously this cost analysis must be viewed against the

differences in the kind of data obtained from the two approaches.

The SMAC vans do get trained investigators to the scene. NHTSA

can best evaluate if this capability is justified in view of the

multidisciplinary accident investigating teams. Since MDAI teams

report on 1500-2000 cases per year from a perspective that is

broader than crash dynamics, it seems advisable to maintain this

capability.
Auto Collision Data

February 17, 1975

Page 58

The field trial of 100,000 - 200,000 passive restraint

equipped cars in a representative sample would cost 30 - 60

million dollars first cost plus annual analysis expense.

Thus in addition to the current accident program of

approximately $5 million covering such activities as MDAI, FAR,

Level II reports, NHTSA and the Congress should consider adding

a mass accident data system that might cost $5 - 20 million

annually, a precision crash dynamics system (probably sophisticated

crash recorders) at a first cost of $2 - 4 million, and

finally a field evaluation of passive restraints costing $30 -

60 million. Table 4 summarizes the existing programs and the

recommended alternatives for the additional data that we deem

to be required.

The genesis of this OTA study was an issue concerning

sophisticated crash recorders and their proper use in accident

data retrieval.

TWO types of crash recorders have been developed under

NHTSA sponsorship.

one of these, commonly known as the “tape recorder,” was

developed by AVCO Systems Division, Wilmington, Massachusetts.

It is designed to measure and record vehicle parameters before,

during and after a crash. The time history of the following

quantities is recorded prior to the crash:
—

Auto Collision Data

February 17, 1975

Page 59

TABLE 4

EXISTING AND PROPOSED PROGRAMS

DATA

and Police

Using TAD

and Police

Using VDI

and Police

Taking

MASS ACCIDENT

FILE

(500,000-1,000,000

REPORTS ANNUALLY)

$3- $10 Per

Report, North

Carolina Prototype

Upgraded Severity

Capability as

Compared to system

Above

$10-$20 Per Report

Wayne State - Volvo

Prototype, Probably

the Best Severity

been Demonstrated

for this file

$10 Per Report

for Severity Plus

$3-$10Per Report

for all other

information

PRECISION CRASH

DYNAMICS

(2,500-5,000

REPORTS ANNUALLY)

$2 - $2.5 Million

Annual Personnel

Charge Plus $1.5-

$2 Million First

cost

SPECIAL

STUDIES

4
.

Auto Collision Data

February 17, 1975

page 60 Table 4 - continued

Multidisciplinary

Accident

Investigation

reams (MDAI)

Fatal Accident

Reporting System

Level II

Restraint System

Investigation

Field Trial of

Uncertain and/or

Expensive Safety Aids

MASS

ACCIDENT

FILE

PRECISION CRASH

DYNAMICS

$2- $4 Million First

costs Plus Annual

Analysis & Maintenance

costs of $0.5 - $1

Million

SPECIAL STUDIES

1500 Reports/year

At $2000 Per

Report on Scene,

$800 Per Report

Off Scene

55,000 Death

Reports Per Year

Contemplated At

a Cost of $1

Million, Uncertain

Severity Indications

Analysis of

Restraint System

Effectiveness

From Police and

Medical Reports,

$100 Per Case

100,000 – 200,000

Car Field Trial

of Passive

Restraints $30-

$60 Million One

Time Cost
Auto Collision Data

February 17, 1975

page 61

Brake pressure (200-2000 psi, accuracy ± 7%

Steering wheel motion (1260°, accuracy ± 3%)

Speed (as derived from the speedometer cable)

(o - 120 mph, speedometer accuracy)

Longitudinal and lateral vehicle acceleration

+

- 1 g, accuracy ± 5%

During the crash is recorded the time history of:

+

Longitudinal acceleration (- 50 g, accuracy ± 3%)

+

Lateral acceleration (- 50 g, accuracy ± 3%)

Vertical acceleration (in vehicle coordinates)

(± 50 g, accuracy ± 3%)

Prior to the crash, the recorded data are sampled at a 20 per

second rate. During the crash, the recorded data are sampled at

a 200 per second rate. The duration of the tape record is from

6 minutes prior to the crash to 10 seconds after the crash. A

garden variety endless-loop 8-track cartridge is used as the storage

element.

Recording is done in digital (PCM) format. The total system

includes each of the several sensors, a crush sensor and a recorder,

packaged separately.

The other recorder, commonly known as the “disk recorder,”

was developed by Teledyne Geotek, Garland, Texas. It is a single

unit that records, only during the crash interval, the time history

of lateral, longitudinal accelerations. The range of accelerations

+

measured is - 50 g, with an accuracy of ± 8%.
.

Auto Collision Data

February 17, 1975

Page 62

The disk recorder is much simpler and less expensive than the

tape recorder, and has been purchased and installed in experimental

quantities by NHTSA. 1050 have been installed in fleets throughout

the country, including air bag equipped cars.

The tape recorder is intended to provide data that could give

useful information on the handling, braking, speed and forces

experienced by the vehicle prior to the crash. Both recorders

provide a crash-acceleration time history, which yields information

on the forces to which the vehicle was subjected during the crash,

and which, if properly interpreted, can give magnitude and

direction of crash severity.

In Fiscal Year 1975 testimony, a total cost estimate of $10

million for a crash recorder program was presented. This program

would have procured 100,000 disk recorders as compared to the

previous 85,000 disk recorders (at $75 per unit) and 15,000 of

the more expensive tape recorders for a total cost of $15

million. The program costs include support for initial purchase

and funds allocated for analysis of the data provided by the

recorders.

The Transportation Systems Center of the Department of

Transportation (Mr. Louis Roberts) has examined the feasibility

of a somewhat cheaper, all solid state, more accurate alternative

to the Teledyne Geotek disk recorder, and have concluded that

such a unit could be built at a unit cost of $125 in quantities of

100,000. With this recorder, three-axis accelerations would be

measured to 1%.
Auto Collision Data

February 17, 1975

Page 63

C. Y. Warner and Joseph Free of Brigham Young University,

and Brian Wilcox and Donald Friedman of Minicars, Inc.* have

proposed as a severity measuring device a very simple two-axis

integrating accelerometer whose outputs are change in velocity

during the crash interval. The Breed Corporation is also

developing two cheap crash recorders. One will provide information

indicating that the crash resulted in a velocity change of more

than 30 mph. This is accomplished by a latching system. The

other system provides a direct reading of crash severity. A

combination of Coulomb and viscous forces acting on a mass provide

a system that is insensitive below a threshold, responds to the

vehicle change in velocity during the crash, and latches after

the crash indicating the change in velocity experienced.

We believe that development of a cheap and simple severity

measuring and recording device is highly desirable. There

appear to be many feasible design alternatives to the Warner

device, and they should be examined. A recorder that is

designed to measure average acceleration during the crash

interval, as opposed to velocity change alone, should be

considered. Lynn Bradford, NHTSA crash recorder program manager,

concurs that only the two horizontal components of acceleration

need be sensed, and that the third axis can be omitted.
.

Auto Collision Data

February 17, 1975

Page 64

5. FEDERAL RESPONSIBILITY AND EXPENDITURES FOR COLLISION DATA

GATHERING

The Federal Government through the Department of

Transportation, has undertaken the responsibility for setting

safety and damage-limiting standards for motor vehicles. The

costs of standards put into effect thus far is more than $2.5

billion annually. It would appear that prudent and responsible rulemaking would imply that each such standard should be

promulgated only after acquiring through data collection and

large scale experiment a thorough understanding of the frequency

of occurrence of the hazards to which the standard was addressed,

the extent to which a design to the standard would mitigate the

outcome in terms of damage or injury, and the consequent benefits

as related to the estimated costs. But because of the dearth of

data, rulemaking has been based instead on guesswork and judgment.

Fortunately, two standards (energy absorbing steering column and

belt restraints) appear on the basis of limited evidence to be

highly successful. TWO others, HPR glass and head restraints,

appear to be beneficial; but the others remain to be evaluated,

and in the meantime, their costs continue to be borne by the public.

Motor vehicle collision loss is an enormous national problem

that requires centrally coordinated solutions, both in terms of

motor vehicle standards and highway designs. Implicit are both

the need and the responsibility for centrally supported collection

of collision data, representative of all the States, from which may

be drawn inferences regarding the need for and benefit of vehicle

and highway design changes. The establishing of a central collision

data file further implies a need and responsibility for standardization of reporting systems and formats so that input data from
Auto Collision Data

February 17, 1975

Page 65

many sources can be combined. The federal government should

undertake these responsibilities as the central and coordinating

activity for collection of crash data.

In addition to the question of responsibility, there is the

question of capability. On this question, John Versace of Ford

Motor Company 16/ has the following comment.

“Mass accident data acquisition, processing, analysis,

and broad scale distribution requires great effort and

much resource. Only the federal government has the

necessary resource and easy access to the agencies which

can supply information. Furthermore, it seems that it is

the responsibility of the federal government to assemble

data which will allow an accurate public review of the

real dimensions of the crash and injury problem on our

highways.”

The current level of Federal expenditure for the collection

and analysis of automobile collision data is $5-6 million yearly.

A few examples will be presented to illustrate that the justifiable

levels of expenditure may be much higher than the current amounts.

1. Each traffic fatality is a catastrophe that costs society

2/ current Federal expenditures ‘or approximately $200,000.–

collision data gathering average less than 0.06% of the cost

of traffic deaths.

2. 28 million automobile accidents cost the United States

$22 billion annually. Federal expenditures to collect data

average less than 22¢ per accident-involved automobile, and less

than 0.03 % of total losses (see Figure 1).
Auto Collision Data

February 17, 1975

Page 66

DEATH

$10 BILLION

.

ANNUAL COST OF MOTOR VEHICLE ACCIDENTS

●

$6 Million

NHTSA EXPENDITURES ON CRASH DATA COLLECTION

FIGURE 1. Comparison of the cost of motor vehicle

accidents with Federal expenditures to

acquire and analyze crash data.
Auto Collision Data

February 17, 1975

Page 67

3. The cost of 5 mph no-damage bumpers front and rear has

been estimated as $119 per car (first cost) plus about

$100 in added lifetime fuel costs. The total consumer

expenditure required to equip all cars is about $2.2

billion per year. Because of the paucity of hard statistics

or the frequency distribution and cost of low-severity

accidents whose damage the bumpers tend to mitigate, there

is an uncertainty of at least 10% or about $200 million,

in the estimate of the benefits; this uncertainty alone

is more than 30 times the current Federal data collection

expenditures.

4. Continuing uncertainties about the effectiveness of

seat belts lead to differences in estimates of numbers of

lives saved (at 50% belt usage) of at least 8000 annually

representing a societal gain or loss of $1.6 billion. This

uncertainty is more than 250 times the current Federal

expenditures on data collection and analysis.

Thus high levels of expenditure appear justified by the

magnitude of the motor vehicle collision loss program and its

uncertainties. They are not necessarily required to do the

job. The actual amounts needed must be determined after the

development of a comprehensive plan that specifies in detail

the information needed, the quantities of data and rates at

which it is to be gathered, and how the plan is to be implemented.

The benefits of a data collection and analysis effort can be

easily seen when it is used to resolve a choice between two approaches

to solving a problem. The benefits are less obvious, just as in any

research effort, when the outcome is unpredictable in terms of

establishing the measures and costs of reducing damage, injury and

death.
Auto Collision Data

February 17, 1975

Page 68

6. LEGAL ASPECTS OF CRASH RECORDERS

Questions that are often brought up with regard to automobile

crash recorders are (1) whether crash recorder evidence is adminsible in a court of law; (2) should it be admitted?; (3) can it

be prevented from being admitted?

There is a useful parallel in the inflight recorders installed

in commercial airplanes. In the event of a crash, the data in

these recorders is read out and interpreted by the Federal Aviation

Administration or National Transportation Safety Board staff

personnel. Section 701 (e) of the Federal Aviation Act forbids the

use of the NTSB report in any suit or action for damages arising

out of an accident. The original policy considerations were that

if such possibly legally damaging reports could be used in court,

it would inhibit possible sources of information important to the

cause of NTSB in promoting safety. But it is possible to get the

FAA or NTSB staff member who read out the recorder to testify

as to the facts and thus the “facts”, data read or heard from the

recorders can be received as evidence toward the proof or defense

of an allegation of negligence. Neither the airlines nor the

*

government has any privilege to exclude or restrict such evidence.

Similarly one could expect that automobile crash recorder data

could be admitted in evidence in a court of law; but there would be

the usual problem of qualifying the evidence. In the absence of

a stipulation of the opposing party as to the authenticity of the

data and the reliability and accuracy of the

party would successfully have to demonstrate

reliability and accuracy of the recorder and

person who read out the data.

recorder, the moving

to the court the

the expertise of the
Auto Collision Data

February 17, 1975

Page 69

On the question of whether crash recorder data should be

admitted, the main point again is whether the recorder is reliable,

accurate, properly read out, and provides a record of the particular event in question. The data of itself is not dispositive of

liability, but merely serves as certain evidence of the event. As

indicated earlier in this report, there is good correlation between

the crash severity a recorder might measure and the extent of crash

deformation to the vehicle in which it is installed; and it would

be difficult to refuse evidence on the crash severity magnitude as

interpreted from vehicle deformation. Thus if the recorder provides

good evidence of the event, it seems appropriate that that evidence

should be admitted.

It may be possible to restrict through legislation the

admissibility of crash recorder evidence, particularly if the

recorders are government-owned and the records are retrieved and

interpreted by government employees. Consider, however, the

objective of a very simple and widely used integrating accelerometer

that is conveniently and reasily read by any police accident

investigator without special training. It would appear difficult to

prevent testimony by a layman -- say a tow-truck operator or an

auto mechanic -- as to what he saw immediately after the accident.

In summary, we believe that (1) the data from a crash recorder

would be admissible, if it meets necessary qualifications, in a court

of law; (2) the data should be admitted if it is good evidence;

(3) it will be difficult to prevent admitting crash recorder data,

even by Federal law, if the record can be easily read by an untrained

person.
Auto Collision Data

February 17, 1975

Page 70

REFERENCES

1. More Sophisticated Data Collection for an Improved Accident

Data System, Edwin A. Kidd, Calspan Corporation, January

27, 1975; included as Appendix A of this report.

2. Review and Critique of National Highway Traffic Safety

Administration’s Revised Restraint System Cost Benefit

Analysis, Economics and Science Planninq, January 22, ;~:y.

3. Cumulative Regulatory Effects on the Cost of Automotive

Transportation (RECAT) , Office of Science and Technology

(White House), February 28, 1972.

4. Letter from Richard Wilson, General Motors Corporation

February 4, 1975. Included as Appendix E to this report

5. Passive Protection at 50 Miles Per Hour, U. S. Department

of Transportation, National Highway Traffic Safety Administration, June 1972.

6. Analysis of Effects of Proposed Changes to Passengers Car

Requirements of MVSS 208, Motor Vehicle Programs. National

Highway Traffic Safety Administration, Department of Transportation, August 1974.

7. Analysis of the Benefits Derived from Certain Presently

Existing Motor Vehicle Safety Devices: A Review of the

Literature, Lindsay I. Griffin III, University of North

Carolina, December 1973.

8. National Accident Data Systems, C. Thomas Terry, General

Motors Environmental Staff, Proceedings, Automotive Safety

Seminar, June 20-21, 1973.
Auto Collision Data

February 17, 1975

Page 71

9. Statistical Inference from Multidisciplinary Accident

Investigation, James O’Day, Highway Safety Research

Institute, University of Michigan, August 1974, (Department

of Transportation Report--DOT-801 111) .

10. Statement by B. J. Campbell, Highway Safety Research

Center, University of North Carolina, Automobile

Collision Data Workshop, January 17, 1975. Included as

Appendix C to this report.

11. S ummary of Remarks at the Automobile Collision Data

Workshop, Lawrence Patrick, Wayne State University.

January 20, 1975; included as Appendix D to this report.

12. Statistical Rationale for the Number of Automobile Crash

Recorders Purposed for Procurement and Installation by

NHTSA; National Highway Traffic Safety Administration

(Received February 5, 1975) ; included as Appendix F to

this report.

13. Crash Recorders and Alternate Methods of Defining Crash

Severity, James O’Day, Highway Safety Research Institute,

University of Michigan (received February 8, 1975) ;

included as Appendix G to this report.

14. Adequacy and Limitations of Current Data Systems, Marie

D. Eldridge, National Highway Traffic Safety Administration,

January 16, 1975; included as Appendix H to this report.

15. A Discussion of Data Gathering Systems, Edwin A. Kidd,

Calspan Corporation, January 16-17, 1975; included as

Appendix I to this report.

16. Mass Accident Data Acquisition and Why It’s Needed, John

Versace, Ford Motor CO., January 16, 1975; included as

Appendix J to this report.

17. Reports on Traffic Accident Research, VOlVO, March 1973,

A.B Volvo, Car Division, Gothenburg, Sweden.

18. Position Statement on an Expanded, Low-Cost National Accident

Data Collection Program. J. R. Cromack, B. J. Campbell, L.

Patrick and B. O“Neill, February 7, 1975; included as

Appendix K to this report.
-

Auto Collision Data

February 17, 1975

Page 72

19.

20.

21.

22.

23.

24.

25.

Automotive Recorder Research - A Summary of Accident Data

and Test Results. S. S. Teel, S. J. Peirce and N. W.

Lutkefedder, Proceedings of SAE 3rd International

Conference on Occupant Protection, July 10-12, 1974.

Energy Basis for Collision Severity, Kenneth L. Campbell,

General Motors Corp. , Proceedings of SAE 3rd International

Conference on Occupant Protection, July 10-12, 1974.

Ford Motor Co. submission to NHTSA Docket 74-15, Higher

Speed Protection Requirements, September 19, 1974.

Automotive Recorder Research and Its Effects on Future

Vehicle Safety, S. S. Teel and N. W. Lutkefedder, National

Highway Traffic Safety Administration (undated) .

The Mechanics of Automobile Collisions, Felix Rosenthal et

al, Naval Research Laboratory Memorandum Report 2417, May

1972.

Comparison of Three point Harness Accident and Laboratory

Data, L. Patrick, N. Bohlin and A. Anderson; Wayne State

University, Aug. 20, 1974.

Resolution of the National Motor Vehicle Safety Advisory

Council, November 14, 1974.
OFFICE OF TECHNOLOGY ASSESSMENT

Automobile Collision Data

AN ASSESSMENT OF NEEDS AND METHODS OF ACQUISITION .

FEBRUARY 17, 1975

PREPARED AT THE REQUEST OF

THE HOUSE COMMITTEE ON APPROPRIATIONS

VOLUME II

PREPARED UNDER CONTRACT OTA Cll

ECONOMICS & SCIENCE PLANNING, INC.

120018 TH STREET N.W.

WASHINGTON, D. C. 20036
APPENDICES

Page

APPENDIX A ✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎ ✎ 1

More sophisticated Data Collections for an Improved Accident

Data System. Edwin A. Kidd, Calspan Corporation, January 27,

1975.

APPENDIX B . . ............................................** . 7

Letter from John Versace, Ford Motor Co., February 6, 1975.

APPENDIX C ● *****9 ● OmmO*** ● *mm*o** ● *9**,.* ● *.m.... . 31

Statement at the Automobile Collision Data

Highway Safety Research Center, University

January 17, 1975.

Workshop, B. J. Campbell,

of North Carolina, - -

APPENDIX D . . . . . . . . . . . . . . ● .... . . . . . . . .. . . 37

Summary of Remarks at the Automobile Collision Data Workshop,

Lawrence Patrick, Wayne State University, January 16, 1975.

APPENDIX E ............................................ 53

Letter from Richard Wilson, General Motors Corp., February 4, 1975.

APPENDIX F ● ..................... .......................... 61

Statistical Rationale for the Number of Automobile Crash

Proposed for procurement and Installation by NHTSA; National

Highway Traffic Safety Administration (received February 5, 1975).

Recorders

APPENDIX G ● .....* ● a..*e* ● .****** ● .*.*.9* ● e*.. . ....77

Crash Recorders and Alternate Methods of Defining Crash Severity,

James O’Day, Highway Safety Research Institute, University of

Michigan (received February 8, 1975).

,- i -

.
Page 2

Page

APPENDIX H .................................... ● 87

Adequacy and Limitations of Current Data Systems, Marie D. Eldridge,

National Highway Traffic Safety Administration, January 16, 1975.

APPENDIX I ●✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎ ✎ . .......101

A Discussion of Data

Corporation, January

Gathering Systems, Edwin A. Kidd, Calspan

16-17, 1975.

APPENDIX J ● ...................... . . . . . . . ............... 119

Mass Accident Data Acquisition and Why It’s Needed. John Versace,

Ford Motor Company, January 16, 1975.

APPENDIX K ✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎ ✎ 133

Position Statement on an Expanded, Low-Cost National Accident

Data Collection Program, J. R. Cromack, B. J. Campbell,

L. Patrick and B. O’Neill, February 7, 1975.

APPENDIX L ● *.**** ● .*.**** . ●   ** 0= .*0*. *OG*O .. ....139

Resolution of The National Motor Vehicle Safety Advisory Council,

November 14, 1974.

APPENDIX M ● ................................................. 141

The Need for Standardization in Reporting Collision Damage and

Injury in Traffic Accidents, J. Robert Cromack, January 16-17, 1975.

APPENDIX N ....................... ● ..................... ...147

Regulatory Rulemaking Based on Less Than Total Information,

David Morganstein, Center for Auto Safety, and L. A. Goldmuntz,

Economics & Science Planning, Inc., Received February 21, 1975.

APPENDIX O ✎✎✎✎✎✎✎✎✎✎✎ ✎ ✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎ ✎ 151

Automobile Collision Data Workshop: Agenda; Scheduled Presentations;

Salient Residual Issues. January 16-17, 1975.

APPENDIx P ✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎✎ ✎ ............... . ......159

Letter from John Garrett, Calspan Corp., March 12, 1975, and

Attachment.

- ii -
APPENDIX A

MORE SOPHISTICATED DATA COLLECTIONS

FOR

AN IMPROVED ACCIDENT DATA SYSTEM

Edwin A. Kidd

CALSPAN CORPORATION

January 27, 1975

-1-
MORE SOPHISTICATED DATA COLLECTION FOR AN

IMPROVED ACCIDENT DATA SYSTEM

EDWIN A. KIDD

CALSPAN CORPORATION

January 27, 1975

It is essential that NHTSA have a national data bank for

surveillance and effectiveness studies related to the impact of standards

on accident, injury and fatality frequencies. The relatively small output

of the special federal teams and/or the higher quantity, but low content

state data banks are inadequate for the purpose. In addition to information

on the general accident environment, vehicle damage and occupant injuries,

details of the impact environmmt -- velocity at impact, change in velocity

during impact and possibly, vehicle deceleration -- are required for a

sample Of 100,000 to 500,000 automobiles annually.

-2-
27 January 1975

CANDIDATE SYSTEMS

Candidate systems for achieving the required information are:

● Crash recorders, with accident, vehicle and

occupant information supplied by “conventional”

investigations by police and/or special teams.

Off-scene computer reconstruction of

as reported by police and/or special

accidents

teams.

Computer aided investigation and reconstruction

of accidents (e.g., SMAC) using appropriately

equipped police and/or special teams.

Use of crash recorders alone to provide data on the impact environment for the required number of accident cases would be prohibitive in cost.

For example, if accidents of tow-away severity or higher are of principal

interest, then 30-40 times as many automobiles must be equipped with crash

recorders as the number of accidents needed annually for analysis*. Also,

and most important, the crash recorder only provides a portion of the data

required; conventional investigative methods must still supply accident

and vehicle descriptions, vehicle deformation, occupant injuries, restraint

system use, etc.

——

*

Additional cost for each accident case would be 30-40 times the cost of

each crash recorder installation.

-3-
27 January 1975

Off-scene computer reconstruction (SMAC) of the more extensively

reported accidents now resulting from the special team studies has already been

demonstrated. A modest amount of additional work on SMAC is required to

increase the generality of the reconstruction of the various accident types.

Also, application of this reconstruction aid to accidents as presently

reported by police should be studied with the objective of determining the

minimum information required for each accident.

The computer aided investigation and reconstruction of accidents

by police offers the most promise for the attainment of the large data base

required. If the use of appropriately equipped accident investigation vans

is determined by individual police agencies to be beneficial for their

present activities, in terms of overall efficiency, then the mechanism for

providing all of the necessary accident data for NHTSA will be accomplished.

Providing the police with equipment that will be cost/beneficial for their

present needs will obviously provide the means for the attainment of the

data required by NHTSA at the lowest cost. Also, the digital format of the

accident descriptions and reconstructions that would be output from this

equipment would result in minimal data processing for a fast response data

bank.

RECOMMENDED APPROACH

The overall objective is the attainment of a consistent, coherent

data bank that will be adequate both in size and specific content for the

purpose and is practical in terms of development time and cost.

Whether police or special teams are used as the basic collection

agency need not be decided immediately. What should be decided as soon as

possible is the efficacy of the computer aids to reconstruction and

-4-
27 January 1975

investigation that have already been developed. The crash recorder may

play a role in further validating these aids; it cannot be seriously

considered as the ultimate data collection method because of prohibitive

cost. A decision to continue with special teams should include the

provision of demonstrated aids for these teams. If police want these aids

and their efforts can be integrated into a national data system, then it

appears axiomatic that a police based system would provide the most for the

least cost.

A program is outlined below for achieving the improved accident

data system:

1.) Install crash

e.g., air bag

validation of

recorders in special automobiles,

equipped vehicles, for additional

computer reconstruction aids.

2.) Accident Reconstruction

a.)

b.)

Continue validation of SMAC via staged crashes

(including crash recorders) for a broad

accident spectrum.

Determine accuracy achievable on police

reported accidents and establish minimum

data requirements as function of accuracy

achievable.

3.) On-Scene Reconstructions

a.) Accident vans for special investigative

teams to improve data consistency and

achieve more accurate reconstructions.

-5-
27 January 1975

b.) Field trials with police agencies to

determine accident reporting and/or accident

reconstruction configurations.

4.) As the result of 1, 2, and 3 (above), establish

national data collection system elements.

TIMING AND APPROXIMATE COST—

Aggressive pursuit of this plan would provide detailed requirements

and set up of the overall system within two years. Meanwhile, the present

multilevel data collection centers would continue to provide data, but with

a transition toward the final system in the second year.

An acceptable, complete data system could be achieved at a cost of

five to ten million dollars annually. Actual costs to NHTSA are dependent

upon the usefulness and acceptability of the investigation and reconstruction

aids to selected police agencies and their subsequent integration into the

system.
APPENDIX B

LETTER FROM JOHN VERSACE

FORD MOTOR COMPANY

February 6, 1975

-7-
Ford Motor Company 20000 Rotunda Drive

Dearborn, Michigan 48121 :

Mailing Address:

P.O. Box 2053

Dearborn, Michigan 48121

February 6, 1975

Mr. Howard P. Gates, Jr.

Economics & Science Planning

1200 18th Street, N.W.

Washington, D.C. 20036

Subject: OTA Automobile Collision Data Workshop

Dear Howard:

It did take some time in a very busy schedule to meet

with you and to put our thoughts down, but we appreciate the

opportunity to express our understanding of, and our position on

the subject of accident data. In regard to societal costs: the

Ford Motor Company submission to Docket 74-15 -- Advance Notice

Concerning Higher Speed Protection Requirements -- contains some

estimates of the additional consumption of resources entailed in

trying to meet a high speed requirement.

It is difficult to determine all the ways in which

inadequate accident data would lead to unnecessary expansion of

costs, but we believe this one example will provide a general

picture of the possible magnitude of such expense. I don’t believe we conclude that raising the crash requirements is the

wrong thing to do, but rather because the cost implications are

so great nothing less than a commensurately significant analysis

and determination of need –- which has not been done –- should

precede any decision.

It is easy to lose sight of the fact that a good

intention, or want, or objective gets converted, by means of a

regulation, into very specific operational requirements and

specifications which the manufacturer must meet, specifications

which may have little to do in the last analysis with the intentions of the regulation. However, the regulation, in its specific

detail, is often defended on the basis of its motivation rather

than on what the particular requirements of the regulation are

-8-
Mr. Howard P. Gates, Jr.

February 6, 1975

Page 2

likely to actually accomplish. Specifically, in this case, if it

is deemed desirable to provide better protection for those people

who are in high speed crashes, then it may or may not follow that

running an automobile into an immovable wall at 45 or 50 mph, and

then comparing readings gotten on accelerometer in dummies against

some mandated criterion level somehow validly signifies accomplishment of the societal goal which motivated the standard. The likelihood of gross erosion of relevance is probably nowhere better

seen than in the accident avoidance series of standards, where

little or no validation has been attempted.

A contrary argument is likely to be heard: that the

need is so great we cannot wait for all the evidence to be in,

that utterly adequate evidence will never be forthcoming, and

thus we must act now. But such an argument seems to beg the

question: for how can we know we must act now -- especially

with some particular countermeasure -- if that determination depends on having adequate data? A variant on this argument is that

it can do no harm and might do some good. But, without data there

is no assurance that particular countermeasures will do no harm,

and certainly a cost without a compensating benefit is a net harm.

I am attaching a COPY of the Ford docket submission on

the higher speed protection requirements proposal, but you will

probably want to give special attention to the brief summary,

“societal Cost Implications of Inadequate Accident Data,” which

puts forth the main points made there.

In addition, I am attaching an updated copy of the

remarks which I made at the Workshop. They are essentially the

same as the statement I read, but there have been some additional

clarifications which I felt were appropriate in view of the discussions which took place at the meeting.

Sincerely,

John Versace

Executive Engineer

Safety Research

Attachments

-9-
SOCIETAL COST IMPLICATIONS OF INADEQUATE ACCIDENT DATA

The demonstration of need for any safety standard must ultimately be

established by accident data -- in all its forms -- if objective safety

standard performance levels are to be achieved. If standard performance

levels are established on a subjective basis, the possibility of very high

societal cost with inadequate return for that cost is very real.

As an example of proposed performance levels which could have severe

societal cost implications consider NHTSA’s Advanced Notice of Proposed

Rulemaking (ANPRM), Docket 74-15 Notice 1. This ANPRM proposes to increase

frontal barrier crash requirements from 30 mph to 45/50 mph -- an increase

in crash energy management requirements of 125 to 177% above that required

today. The notice also proposes to implement the rule on September 30, 1980.

Ford Motor Company’s response to this notice is attached. It presents

the implications of implementing such a proposal in terms of increased car

weight and car length. For example, to meet the frontal crash requirement

alone, a 1974 Ford would be 500 pounds heavier and 16 inches longer; a 1974

Pinto would be 600 pounds heavier and 37 inches longer. Additional weight

would be required to meet side and rear impact, roof crush, and fuel system

crash requirements currently in being or presently proposed in other standards.

Weight increases of the magnitude discussed above imply completely redesigned cars -- not modifications to on-going designs. In addition to new

metal structures, the added weight would require higher performance powertrain

and running gear (brakes, suspensions> steering systems, etc.. . . . ) which in

turn would tend to weigh more. Ford Motor Company markets 16 domestically

manufactured car lines built from eight separate body shell platforms. To

completely redesign these platforms would involve staggering engineering and

investment costs. Annual increased car purchase costs to consumers -- assuming

such a gigantic task could be done at all -- would be on the order of billions

of dollars annually.

Such a major weight increase in cars would have a two-fold effect on the

consumption of energy. The

secondly, additional energy

fuel economy of vehicles would deteriorate and

would be used to manufacture the added weight.

-10 -
Fuel economy may be expected to decrease from the current average of

13.6 miles per gallon by about 10%. This represents an increase in fuel

usage of 25 million barrels each year. Should this weight increase be

applied to the entire vehicle population, the annual fuel economy penalty

would be nearly 200 million barrels. In ten years gasoline purchase costs

would be on the order of $5 billion more per year than 1975.

Adding this weight to 10 million new cars each year would increase

manufactured material requirements

gross effect of the vehicle weight

for finished steel, steel castings

about 20%. The energy consumption

weight in 10 million new cars each

B.T.U’s.

by about 3 million tons annually. The

increases would be to increase the demand

and rubber for the auto industry by

for manufacturing this added material

year would approximate 130 trillion

If all the cars on the road were at the higher weight levels, the total

annual cost increase to consumers would be the sum of the annual cost of the

decreased fuel economy (projected at $5 billion), PIUS the higher costs and

energy associated with manufacturing the heavier vehicles (projected to be

billions of dollars annually). This sustained annual societal cost impact

could take place because of a regulation whose need has not been definitely

or definitively established.

-11-

February, 1975
Ford Motor Company The American Road

Dearborn, Michigan 48121

September 19, 1974

National Highway Traffic

Safety Administration

Docket Section -- Room 5108

400 Seventh Street, S. W.

Washington, D. C. 20590

Gentlemen:

Re: Advance Notice Concerning Higher Speed

Protection Requirements (Docket 74-15:

Notice 1)

Enclosed are Ford Motor Company’s comments on the

Administration’s advance notice of proposed rulemaking to

increase the frontal barrier crash requirements of Federal

Motor Vehicle Safety Standard No. 208, Occupant Crash protection, to 45 or 50 mph effective September, 1980. Ford

has also participated in the preparation of comments being

submitted by the Motor Vehicle Manufacturers Association

and respectfully requests that those comments be incorporated

herein by reference.

The comments address the several areas of interest

cited by the Administrator in the subject advanced notice of

proposed rulemaking. It is appropriate, however, to highlight certain salient points on which the comments expand.

There is the apparent assumption that a ‘manifold

increase in lifesaving capability of occupant crash protection systems” can be demonstrated merely by increasing

the velocity at which a test vehicle impacts a fixed barrier

and having the recorded test results satisfy essentially

arbitrary criteria.

-12-
National Highway Traffic

Safety Administration September 19, 1974

As the Administration well knows, there are many

unsettled questions and unresolved issues with regard to

Standard 208 including the correlation of test device

responses to those of humans, the subjectivity of test

procedure, the questionable appropriateness of the criteria,

etc. Barrier crash tests are not representative of actual

traffic accidents. Meeting some requirement using a test

device having a superficial resemblance to a 50th percentile

male adult positioned in a normal seated position is no

guarantee that human occupants will survive in actual collisions of apparent equivalent severity.

Despite the uncertainty associated with Standard

No. 208, in an effort to aid the Administration in defining

the potential effects of adopting requirements such as those

in this proposal, Ford has conducted a theoretical study

related only to front end impacts using a Simplified model

and idealized assumptions as to restraint systems, structure

behavior, etc. That study, as explained in the attached

comments, convinces us that the results of the Administration's proposal would be to increase the weight of a vehicle

with a Pinto size passenger compartment by about 600 pounds

and that of a Ford size vehicle by between 500 and 900

pounds for a 50 mph barrier impact speed. Length increases

of as much as 37 inches for the Pinto and 16 inches for the

Ford would be required. Specific modifications would be

dependent upon restraint systems parameters that are yet

undeveloped.

It is obvious that vehicle weight increases of

this magnitude will have a pronounced effect on vehicle

cost. The engineering and investment costs necessary for

major redesigns of all existing cars in a short time period

of a few years might best be described as staggering. Based

on our analysis to date, Ford would not be able to meet the

proposed effective date of September, 1980.

These weight and length increase estimates are

based on a simplified, idealized analytical study and we

consider them the minimum changes required, if only the

requirement for front end impact speed was increased. It

is significant that these results are not greatly dissimilar

to those that could be derived from an analysis of the

vehicle designed and built under the Experimental Safety

Vehicle programs. It is also significant to note that

none of the full sized Experimental Safety Vehicles were

successful in meeting the requirements during a 50 mile per

hour barrier crash despite, in some cases, the somewhat

exotic designs employed.

-13-
National Highway Traffic

Safety Administration September 19, 1974

Ford believes that the increased speed requirement

with its attendant cost and weight increases cannot be justified without an analysis of highway accident data showing

that a safety need exists for the proposed increase. The

accident impact speed data currently available with which

to perform a benefit analysis of higher speed requirements

are dependent on subjective human evaluation. Speed

estimates in existing data files are thought to be unreliable because they are formed by witnesses or by accident

investigators having varying degrees of experience.

The lack of a sound data base with which to evaluate

the need for higher speed performance requirements further

underscores the need for a large scale crash recorder program to evaluate the actual crash dynamics. The initial

results of crash recorder analyses have indicated that

impact speeds estimated by police and accident investigation teams are consistently higher than the speed change

noted by the recorder.

Ford is currently engaged in a research project

under DOT contract to define the performance parameters of

a 3000 pound safety vehicle which will be practicable to

manufacture in the mid 1980’s. We believe this research

will be of value in evaluating future motor vehicle safety

needs in the area of higher speed protection. This project

is scheduled for completion in April, 1975.

We, therefore, recommend that NHTSA’s efforts in

the area of higher speed occupant crash protection be concentrated on developing an accurate data base from which

the Administration can determine,on an informed basis, the

safety need, if any, for a barrier crash test and identify

appropriate and practicable test speeds.

At the present time we can only conclude that

adopting the proposal advanced in this notice would have

the certain effect of increasing weight and vehicle size

(with the attendant adverse effects on fuel and material

consumption) and consumer cost. The amount of benefit to

be gained is only speculative.

If we can be of further assistance in explaining

our position, we will be available at the Administration’s

convenience.

“Respectfully submitted,

bgw

Attachments

-14-
ATTACHMENT

September 19, 1974

HIGHER SPEED PROTECTION REQUIREMENTS

DOCKET 74-15; NOTICE 1

COMMENTS OF FORD MOTOR COMPANY

Ford Motor Company, with Offices at The American

Road, Dearborn, Michigan 48121, as a manufacturers of motor

vehicles, is commenting on the Advance Notice of Proposed

Rulemaking concerning Higher Speed Protection Requirements

published in the Federal Register on March 19, 1974 (39 Fed.

Reg. 10273).

The Notice states that the Administration is considering amending Federal Motor Vehicle Safety Standard No.

208 (FMVSS 208) to include a 45 or 50 mph frontal crash

requirement with a suggested effective date of Septmber 1,

1980.

In our evaluation of the Administration% proposal,

we found we were impaled by the lack of adequate factual

information. Analysis of the available accident data lead

us to the conclusion that such data are not sufficiently

reliable to assess safety need.

Review of the public record on FMVSS 208 did not

disclose the existence of technology which would show that

a practicable vehicle could be designed to meet the frontal

impact requirements of that Standard at 50 mph. The

domestic ESV's, including the one built by Ford, represent

the most comprehensive attempts to comply with such a requirement and all of them failed in that endeavor.

Nonetheless, we have gained some insight into the

problem and have prepared the following comments based in

part on engineering judgment, relying heavily upon theoretical

studies.

Technology

The Administration states in the Notice that

based on research which is extensively documented in the

Docket on FMVSS 208, it is of the opinion that technology

has advanced to the point where protection can be offered

in crashes equivalent to those into a fixed barrier at

more than 40 mph. We have examined the public record

concerning FMVSS 208 and have found no evidence that the

Administration has ever conducted the complete test series

required by FMVSS 208 even at 30 mph, much less at 45 or

50 mph.

-15-
Attachment

Page 2

Septmber 19, 1974

Technogy (Cont'd)

None of the domestic experimental safety vehicles

built under DOT contracts met the performance requirements

of FMVSS 208 at 50 mph. These vehicles exceeded the 4000

pound weight objective by between 1000 and 2000 pounds. One

such vehicle even used unconventional lightweight materials

in an effort to minimize weights. These materials are generally impractical for high volume automotive use because

of supply limitations, high cost and lack of adequate manufacturing technology.

More recent higher speed research by NHTSA contractors has concentrated on maintaining passenger compartment integrity independent of programs to develop restraint

systems* Advanced structures have not been evaluated in

combination with advanced restraint systems in a 50 mph

fixed barrier impact test series which would otherwise

conform to FMVSS 208 although the intent to do so has been

expressed in requests for contract proposals issued by NHTSA.

This was noted by Dr. Patrick Miller of Calspan

Corporation in his statement before the Senate Commerce

committee on February 21, 1974. He stated that “although

impressive structural performance has been demonstrated

during frontal collisions, we have not yet developed restraint

systems which could take advantage of these advances”.

Another problem which has not been adequately considered is the possibility of adverse consequences on occupants of vehicles designed for a 50 mph barrier impact when

they are involved in lower speed impacts. The possibility

exists that due to increase in vehicle stiffness the injury

level in low speed collisions will Become worse.

Many of the crash tests have been conducted at

test weights substantially less than that required by FMVSS

208. Under DOT Contract HS-257-2-461, ‘Frontal and Side

Impact Crashworthiness-Compact Cars” the contractor conducted the crash test without any dummy occupants and with

the vehicle weight 700 pounds under that required by FMVSS

208. The effect of added weight is to place even greater

demands upon the vehicle structure and, thus, to produce

substantially different results.

Further, our review of structural integrity research

under NHTSA contracts indicates that these efforts have not

been directed toward designs which are practicable in high

volume production. The usefulness of the resultant designs

for commercial marketing has been inadequate in most cases.

For example, the domestic ESV's were five passenger sedans

with the occupants tightly packaged while the exterior
Attachment

Page 3

September 19, 1974

Technology (Cont'd)

dimensions were equivalent to current vehicles capable of

carrying six passengers. One NHTSA contractor raised the

body of a Pinto six inches higher off the ground and moved

the driver four inches into the rear passenger space.

(DOT Contract HS-113-3-746, "Crashworthiness of Subcompact

Vehicles”)

We anticipate that the structural modifications

introduced to meet the 50 mph fixed barrier impact requirement would aggravate any existing car to car impact compatibility problems. The stiffer frontal structure and

greater mass would have an effect in frontal, rear and side

impacts.

Size and Weiqht Effects

There is only minimal data and limited experience

with vehicle designs needed to approach a 45 or 50 mph

fixed barrier frontal impact requirement. Therefore, we

have attempted to extrapolate data from existing cars to

determine the size and weight effects of the Administration’s proposal. The results of Ford's and other domestic

ESV programs, along with additional Ford research, were

used even though the ESV’s did not meet the occupant protection requirements of FMVSS 208 at 50 mph and exceeded

the vehicle weight objective by large margins.

The test data used as a basis for the engineering

assumptions and projections were gleaned from recorded

force and acceleration measurements upon various anthropometric test devices. Though such data was found to lack

repeatability, it nevertheless was averaged and used for

directional guidance.

Simplified analytical techniques were used along

with assumed performance parameters for advanced restraint

systems to derive an estimate of the size and weight

increases necessary to meet the proposal.

For purposes of this analysis, the parameters for

an advanced air bag system and an advanced belt restraint

system were hypothesized to represent restraint systems

which are not currently available but which may be possible

by September, 1980.

The results of numerous barrier crash tests were

examined to evaluate the performance of various experimental

and production belt and air bag restraint systems. Values

for effectiveness time, rate of deceleration onset, and

equivalent uniform deceleration or “square wave” deceleration were then determined. The key criterion was the 60 g

deceleration limit of FMVSS 208. We concluded that for an

-17-
Attachment

Page 4

September 19, 1974

Size and Weight Effects (Cont'd)

advanced belt restraint system, a deceleration curve with

an effectiveness time of 20 milliseconds, a uniform onset

rate of 1200 g/see, and a constant deceleration of 40 g’s

gave an idealized representation of the deceleration which

could be produced on the chest of an anthropometric test

device. For an air bag, the values of 40 milliseconds

effectiveness time, 1500 g/see and 48 g’s were determined.

The deceleration levels represent the square wave that

would simulate the average of the peaks and valleys of a

dynamic curve in which the peaks would still remain under

the 60 g limit of FMVSS 208. Onset rates and effectiveness times were chosen based on predicted future system

performance capabilities.

The advanced belt system would include a crash

sensor and a preloader device and possibly a load limiting

webbing material. The advanced air bag system would require

developing improvement to present systems to achieve effectiveness within 40 milliseconds.

The restraint system parameters were used with a

simple mathematical model consisting of two point masses

representing vehicle and occupant. Idealized occupant

stopping distances were determined and then compared with

the available vehicle crush and interior occupant space.

The vehicle deceleration necessary to produce the assumed

occupant deceleration was also computed.

The output of the simple mathematical m-cl thus

gives an indication of the amount that a vehicle must be

lengthened or stiffened to approach a 45 or 50 mph barrier

impact requirement. The length and stiffness increases

were used to determine weight effects using engineering

judgment based on Ford experimental results and ESV experience, and a review of the ESV'S designed by others.

One particular assumption included in the length

calculations is that 65% of the added length will actually

crush during impact. Deformed structure would occupy the

remaining 35% of space. The frontal area occupied by

relatively incompressible components such as the engine

are considered unavailable for vehicle crush. However,

the space occupied by the engine was also considered available for the deformed structure. For purposes of this

analysis, length added to the vehicle was considered

totally usable for computing crush distance up to the

point where the 65% efficiency level was reached. After

that point, 1.54 inches of vehicle length were added for

each inch of crush length needed.

-18-
Attachment

Page 5

September 19, 1974

Size and Weiqht Effects (Cont'd)

The resultant length increases, stiffness, and

weights are shown in Fig. 1 for a vehicle with a Ford size

passenger compartment and Fig. 2 for one with a Pinto size

passenger compartment.

The Ford size car with an advanced air bag system

intended to meet a 50 mph impact level would be over 16

inches longer and an estimated 530 pounds heavier than the

current Ford. The same car with an advanced belt restraint

would only be 2.4 inches longer than the 1974 model but would

be nearly 900 pounds heavier.

The Pinto size car with an advanced air bag system

intended to meet the same 50 mph requirement would become

37 inches longer and an estimated 600 pounds heavier than

the 1974 version. Under the assumptions for the advanced

belt restraint, the Pinto would be 18 inches longer and 630

pounds heavier than the existing car.

increased

system.

result on

Figures 1

lished.

Front end structural stiffness would have to be

substantially for both cars with either restraint

Lesser, although dramatic, weight increases would

both Ford and Pinto size vehicles as shown in

and 2 if a 45 mph barrier impact goal were estabThese weight increases are estimates for meeting

only frontal impact requirements. No provision has been

made in this estimate for increased side, rear and roof

structure which we anticipate would be necessary to meet

the existing levels of such Standards as FMVSS 214, Side

Door Strength, FMVSS 216, Roof Crush Resistance and FMVSS

301, Fuel System Integrity. Structual modifications would

be necessary to withstand the increased static or dynamic

test loads imposed as a result of the weight added to the

vehicle to meet the increased frontal impact speed. The

weight increase resulting from these side, rear and roof

structural modifications would cause further changes to be

made in the frontal structure to meet frontal requirements.

These effects would be more pronounced on small cars under

3500 pounds curb weight due to the provisions regarding curb

weight in FMVSS 214 and FMVSS 216. Neither is there provision in these weight estimates for revision or deletion of

any other standards.

-19-
Attachment

Page 6

September 19, 1974 Size and Weiqht Effects (Cont'd)

The weight and length additions shown in Figures

1 and 2 were derived, in part, using simplified analytical

techniques which do not fully consider the dynamic interactions of vehicle structure, restraint system and test

device. They represent minimum levels of vehicle modification which we believe would be necessary to approach the

frontal impact performance levels of FMVSS 208 at 45 and

50 mph. Restraint system performance parameters were chosen

which we believe are possible by 1980, but do not represent

any system which we currently have available. Vehicle structures with the necessary frontal crush characteristics would

have to be developed. Objective, repeatable conformance

demonstration procedures for FMVSS 208 have yet to be

developed. We therefore consider these estimated weight

and length increases to be minimum levels.

The weight increase shown in Fig. 1 includes that

due to structural additions to meet the higher barrier speed

requirement plus added weight to upgrade such areas as

engine, brakes, suspension and steering. Weight estimates

for these other systems were determined by increasing their

weight in proportion to the increase in structural weight.

This was done by determining the portion of total vehicle

weight due to the other systems for several large size

vehicles as shown in Fig. 3. The portion of total weight

contributed by each system was found to remain fairly constant. The increased weight of these systems was computed

by an iterative process based on the added structure weight.

This process would add weight to the various supporting

systems for each pound of crashworthiness structure added.

We realize that in a practical sense weight additions occur

in discrete increments.

A similar analysis was conducted for smaller size

vehicles to determine the weight additions for a Pinto.

(See Fig. 4) .

cost

We have not determined the cost effect of the

proposal, but it is obvious that addition of this amount

of weight will result in substantial vehicle cost increases.

The engineering and investment cost to redesign all of our

vehicles to attempt to meet a 45 or 50 mph requirement

would be staggering.

Timinq

The vehicle modifications required to meet a 45 or

50 mph barrier impact requirement are so extensive that we

would be required to redesign all of our affected vehicles.

After a final rule of this type is established, technology

-20-
Attachment

Page 7

September 19, 1974

Timing (Cont'd)

is available, and practicability iS achieved, it would take

approximately three years to redesign and retool a single

car line family.

Ford normally cannot develop more than two totally

redesigned car line families in the same model year due to

manpower and facility limitations and available capacity

within the tooling industry. It would require a total of

four additional years to introduce new designs of all existing passenger car models. However, Ford has never before

undertaken a task of this magnitude. Even this cycle is

optimistic as it is unlikely the tooling industry could contain the magnitude of such programs if all domestic automobile manufacturers found it necessary to implement similar

redesigns.

On the basis of our analysis to date, we could not

meet a Septmber, 1980 effective date for all cars, even if

the means of meeting the proposed requirements were fully

developed. Due to the uncertainties that now exist, we

cannot determine whether or not we can meet this date even

on one car line.

A new car body and chassis design is produced for

a minimum of three years and in many instances can exist

for eight years before a major redesign. Therefore, the

redesign program that would be required by the proposal

would probably obsolete relatively new car lines before

the end of their normal cycle with additional cost consequences.

The precise timing effects of the Administration’s

proposal have not been determined. Small cars would cease to

exist as they are known today and large CarS might well become impracticable due to increased size. We do not know

what vehicle model mix the market would support if it is

artificially constrained by a requirement which has such

a pronounced effect on vehicle size.

Accident Data Analysis

Ford and others have previously noted the unreliable nature of reported accident speeds available for

analysis. The source of data errors and some of the

methods which have been used to adjust these data are

shown in Exhibit I. Recent crash recorder results have

confirmed that reported crash speeds are usually too high.

-21-
Attachment

Page 8

September 19, 1974

Accident Data Analysis (Cont'd)

Twenty accident cases involving vehicles equipped

with crash recorders were summarized in SAE Paper 740566 by

S. S. Teel et all of the National Highway Traffic Safety

Administration (NHTSA). The results of an analysis comparing each case vehicle’s velocity change, as reported by the

police and/or an accident investigation team, are summarized below. The impact speeds used in this analysis and

their differences are contained in Exhibit II.

The accident cases in Teel's paper which contained

the necessary information were used to construct a sample of

the population of differences between velocity “changes estmated by an accident investigator and the velocity change

experienced by the vehicle, as reflected by the crash recorder. The sample of 22 differences as tested for normality using the Kolmogorov-Smirnov test2

and the hypothesis

that the population of impact velocity change differences

is normally distributed could not be rejected. Although our

sample of accident cases is small, it indicates that the

distribution of the difference in estimates is a bell-shaped

curve centered at 14 mph (the sample mean) with an estimated

standard deviation of 11.9 mph. Using these figures, we

are 95% confident that ten percent of the reported impact

speeds overestimate the true change in velocity by at least

35 mph while one-quarter of them overestimate the true

change in velocity by at least 25 mph.

 An interval which contains the true mean difference between the estimated and the recorded velocity change

of a vehicle in an accident, with 99% confidence, was constructed using the Students-t distribution. This interval,

7.1 mph < Mean Difference < 21.4 mph, indicates that, on

the averaqe, accident investigators can be expected to overestimate accident impact speeds by from 7 to 21 mph. Our

--- - -

1 Teel, S. S., Pierce, S. J., and Lutkefedder, N. W.,

“Automotive Recorder Research --A Summary of

Accident Data and Test Results”, SAE 740566, 3rd

International Conference on Occupant Protection,

July, 1974.

2 Lilliefors, H. W., “On the Kolmogorov-Smirnov Test

for Normality with Mean and Variance Unknown",

JASA, June, 1967.

-22-
Attachment

Page 9

September 19, 1974

Accident Data Analysis (Cont'd)

accident sample also indicates that impact speeds can be

overestimated by as much as 40 mph. These large overestimates do not depend on the magnitude of the crash

recorder velocity change.

As an alternative statistical test, a nonparametric test, the Wilcoxon Matched-Paris Signed-Ranks

Test, also indicates that estimated impact speeds from

accident investigators are positively biased. Based on

crash tests, Teel concludes that changes in velocity

reported by crash recorders are accurate to within ± 2 mph.

Therefore, as a conservative approach, the differences

between the estimated and the recorded changes in velocity in Exhibit II were reduced by 5 mpht ad the Wilcoxon

test was re-run to determine if the velocity differences

could be due to the crash recorder accuracy. The results

still indicate that impact speeds estimated by police and

accident investigators are too high.

The lack of a sound data base with which to evaluate the need for higher speed performance requirements

further underscores the need for a large scale crash

recorder program to evaluate actual crash dynamics.

-23-
EXHIBIT I

September

THE TREATMENT OF RECORDED IMPACT SPEEDS

- A Summary19, 1974

Methods which have been used to deal with reported

impact speeds from the ACIR accident case file are summarized

below.

A.

B.

c.

Cooke, Conrad H., "Safety Benefits of The

Occupant Crash Protection Standard”,

January, 1971.

Cooke reduced all reported traveling speeds by

10 mph to obtain his estimated impact ‘speeds.

 Mela, Donald F., “A Source of Substantial Error

In Estimating The Distribution of Traveling

Speed For Accident-Involved Vehicles II ● *O , DOT,

Septmber 3, 1968.

Mr. Mela stated that, by using the estimated

impact speeds to determine speed distributions,

"the fraction of vehicles in the speed ranges

20-30 mph and 70-80 mph is overestimated by a

factor of 3, and the fractions below 20 mph and

above 80 mph are overestimated by a factor of 17".

If this statement is true, then it suggests that

some variable type of correction factor (and not

a constant 10 mph as Cooke used) be applied to

the estimated impact velocities in the ACIR file.

White, S. B., Nelson, C., "Some Effects of

Measurement Errors in Estimating Involvement

Rate as a Function of Deviation from Mean Traffic

Speed”, Journal of Safety Research, Volume 2,

June, 1970.

White and Nelson show that even if errors in

estimation are non-systematic, an overestimate

of high-speed frequency would be found. That

is because any error of measurement always serves

to inflate the variance of the distribution of

reported values, regardless of the nature of the

data. Thus, reported variance (i.e., the meansquare deviation from the mean) is equal to the

sum of “true)’ variance and “error" variance.

White and Nelson point this out, in suggesting

that high speed estimates would tend to be exaggerated. They state that “errors in estimating

speeds of accident-involved vehicles causes the

-24-
EXHIBIT I

Page 2

September 19, 1974

involvement rate, when plotted as a function

of the speed deviation, to be U-shaped --

overestimated for large derivations (from the

mean) and underestimated for small deviations”.

White and Nelson refer to traveling, not impact,

speed, but the principle is the same in either

case.

D. Grush, E. S., Henson, S. E., and Ritterling,

o. R., ‘Restraint System Effectiveness”,

Report No. S-71-40, Ford Motor Company,

September 21, 1971.

In this report, ACIR impact speeds were converted to barrier-equivalent velocities. The

following factors were considered in the conversion: the estimated relative closing speed;

the weight differential; a center of gravity

adjustment; and an accident location adjustment.

A second method of obtaining the barrier-equivalent value for each accident-involved vehicle

was based on photographs of the vehicle damage

and the study showed that this latter method

produces better results.

E. Mason, R. R., D. W. Whitcomb, "The Evaluation of

Accident Impact Speed”, CAL Report No. YB-3109-V-1,

August, 1972.

This report presents several formulas, one for

each type of vehicle impact, which can be used

to estimate a vehicle% impact speed. It provides some insight into how Calspan may estimate

impact speeds.

-25-
EXHIBIT II

September 19, 1974

IMPACT VELOCITY CHANGES

Recorder

Number

1086

485

485

642

322

335

641

694

596

596

596

641

642

306

463

463

485

25

352

463

94

352

--- -

Reference:

Crash Recorder

Velocity Change

(mph)

20

15

15

10

5

6

13

9

10

10

10

13

10

19

19

19

15

18

15

19

11

15

Accident

Investigator

Estimated

Velocity Change

(mph)

60 +

50

50 to 60

30 ,

25

25 to 30

30

25

25

24 to 26

25

25 to 35

22 to 25

30

30

30

25

25 to 35

22

20

5 to 8

5

Difference

(mph)

+ 40

+ 35

+ 35

+ 20

+ 20

+ 19

+ 17

+ 16

+ 15

+ 15

+ 15

+ 12

+ 12

+ 11

+ 11

+ 11

+ 10

+ 7

+ 7

+ 1

- 6

- 10

Teel, S. S., Place, S. J. and Lutkefedder, N. W.,

"Automotive Recorder Research -- A Summary of

Accident Data and Test Results", SAE 740566,

3rd International Conference on Occupant Protection,

July, 1974.

-26-
(’!)

d

I

EFFECTS R FRONTAL

VEHICLE WEIGHT Additions (LBS. )

WHEELBASE FUEL INCREMENT FMVSS 208

RESTRAINT AVERAGE LENGTH DRIVELINE SYSTEM TOTAL CURB OVER TEST

SYSTEM g’ s INCREASE RESTRAINT BUMPER ENGINE SUSPENSION

sPEE DTYP E

INCLUDING STEERING WEIGHT WEIGHT BASE WEIGHT

S.W.E .2 / Y (%) (LBS)

30 Product ion 11.3 Base 4400 Base 5600

45 A 19.3 6.0 182 20 21 53 69 6 7 358 4759 8% 5958

45 B 22.5 0 283 20 31 81 104 9 10 538 4938 12% 6138

50 A 19.6 16.2 282 20 31 80 104 9 10 536 4936 12% 6136

50 B 26.0 2.4 483 20 52 134 172 14 17 892 5292 20% 6492

Restraint Type B: Seat belt with sensor and preloader - 20 msec. effectiveness - 1200 g/SeC. onset - 40g maX.

1/ Square Wave Equivalent of vehicle deceleration pulse based on impact speed and total crush distance.

2/ Crush length increases in excess of 5 inches are adjusted by a 65% efficiency factor
Figure 2

September 19, 1974

.’

. .

“.

, ,< ;

.,

,,

,. .

,.,

-28-
Figure 3

September 19, 1974

WEIGHT OF VARIOUS VEHICLE_ SYSTEMS

A PERCENTAGE OF TAL GHT

RSV* TORINO FORD LINCOLN AVERAGE

—.— . .

Curb Weight: 3000 4030 4398 5373 !

— . ---- . -- ---- . . . . .

Percentage of

Curb Weight:

Bumper Systems

Engine

Suspension

Driveline

Brakes

Fuel System:

Steering

6.0 %

15. 6%

21. 3%

To maintain

1 5.9% 5 ● 4%

14• 2% 15• 8%

19.8% 18. 5%

the current Ford

5 ● 6% 5.8%

15 0% 15 .0%

17• 5% 19.3%

vehicle 1.6%

range fuel system weight should be

increased at-the rate-of .01415 lb. per

lb. of added vehicle weight. The

fuel tank weight is approximately

17% of the total fuel system weight.

2.0% 1.5% 2.3% 1.8% 1.9% 

---- -

*RSV figures are an average of 10 Unitized vehicles

with curb weights from 2000 to 3300 lbs.

-29-
September 19, 1974

Figure 4

WEIGHT OF VARIOUS VEHICLE SYSTEMS

AS A PERCENTAGE OF TOTAL WEIGHT

PINTO MUSTANG MAVERICK GRANADA AVERAGE

 Curb Weight: 2457 2753 2831 331.9 

Percentage of

Curb Weight:

Bumpers

Engine

Suspension

Driveline

Brakes

Fuel System:

Steering

6.1%

14• 0%

21• 3%

N. A.

14. 6%

21• 7%

6.0%

14• 996

22• 1%

5.7% 5.9%

15• 9% 14• 9%

21• 3% 21. 6%

To maintain the current Pinto vehicle

range fuel system weight should be

increased at the rate of .01415 lb. per

lb. of added vehicle weight. The

fuel tank weight is approximately

17% of the total fuel system weight.

2.0%

1.7% 1.5% 2.0% 1.7% 1.7%

TOTAL: 45.1% 47.0% 46.6% 46.1%

-30-
APPENDIX c

STATEMENT AT THE AUTOMOBILE COLLISION DATA WORKSHOP

B.J. Campbell

HIGHWAY SAFETY RESEARCH CENTER

University of North Carolina

January 17, 1975

-31-
STATEMENT BY B. J . CAMPBELL

University of North Carolina

Highway Safety Research Center

Presented at

Automobile Collision Data Workshop

Sponsored by

Economics & Science Planning

In acquiring automobile accident data several approaches are used

in the U.S.: First, are intensively investigated accident crashes of

which several thousand have been collected. The advantage of this

approach is that the cases are extremely detailed with photographs and

good injury data. The most important disadvantage is that by virtue of

the changing sampling criteria and the small sample size, the ability to

generalize these few cases to the population is restricted heavily.

I believe too much reliance has been made on this type of data for

guiding NHTSA decisions. It leads one to situations in which too much

is made of a small number of cases. For example, in interpreting the 35

or 40 crashes in which air bags are present some feel the crashes support

air bags because relatively few moderate or serious injuries occur.

However, what if these air bag cases

cases in which no protective systems

bag)? What if one found pretty much

were matched with several hundred

are used at all (i.e. no belt or

the same proportion of injuries in

both series? Wouldn’t that suggest that 40 cases is just not enough?

Second is an approach called the tri-level system. There the samples are larger, but the negative aspect is that the reporting threshold

is based on accident severity which results in eliminating certain cases

in which safety belt and perhaps other safety device effectiveness is

greatest.

-32-
Third, and at the other extreme from individual case studies is the

attempt to use an entire state accident data system as the basis on which

to do research and make decisions. The biggest advantage in this case

is the perspective gained from very large sample sizes and the ability

to partition and control the data. But on the negative side many such

systems contain too few content variables of interest. The quality of

reporting may be poor and the injury data is crude.

In my opinion a crucial need in the field of crash injury is the

means to forge a meaningful link between laboratory test crash data and

events as they occur in the field. Much can be gained from laboratory

sled and full-scale crash tests involving dummies, Cadavers or even

live subjects, and also much can be gained from the study of actual

crashes on the highway. But each lacks a significant variable.

In the staged crashes in the laboratory, telemetric procedures are

used for recording data and one can specify in considerable detail the

physical system in which the crash occurs--the "g"-forces, the rate of

onset, delta “v” etc. But when one is forced to use nonhuman subjects

then one is left in the situation of knowing a great deal about the

physics of the crash but knowing little of the actual injuries that

might have occurred in such a crash. On the other hand, in real world

automobile crashes one can learn about the actual outcomes in terms of

survival and injuries, but the input variables mentioned before are

unknown.

The need to link these two systems is apparent. Engineers who

design protective systems need to know about stopping distances, forces,

decelerations, etc. But knowing these things is of too little help

unless one has a way to relate them to real world injuries. An

-33-
illustration of the need for this data link is the NHTSA analysis

conducted in connection with the air bag. This NHTSA analysis

initially indicated that lap and shoulder belts would only reduce

fatalities by 35-40 percent, and that lap belts alone would be of

almost no benefit at all in reducing injuries. These conclusions

were presumably based in large measure on results of crash tests

involving cadavers and dummies. The problem is that these conclusions disagree sharply with studies of tens of thousands of crashes

that have occurred on the highways. Studies from all over the world

indicate that in actual crashes injuries are reduced by lap belts,

and that lives are saved, and that the degree of lifesaving is much

higher than 35 or 40 percent NHTSA has indicated.

It is the very occurrence of this type of disagreement that shows

that the analysis system in each sector (laboratory vs highway) by

itself is inadequate and that means must be found to bridge the gap.

The primary advantage of a crash recorder program would be a means to

forge this link between the two data systems. It would finally be

possible to gather data on a few thousand actual highway crashes in

which crash conditions, the decelerations, the forces, the amplitudes

and so forth would be knowable as well as the injury.

By using these several thousand crash recorded events as a calibration standard it would be possible to work outward to the hundreds

of thousands of other actual crashes in which recorders weren’t

available, and the thousands of lab tests in which recorders are

available but human injury is not.

It is not necessary to have an “infinite” number of crash recorders

in the field, only enough to validate other approaches. I personally

-34-
do not see the crash recorder program as an end in itself but one

which would support and validate other types of crash studies.

My remarks do not suggest the level of detail needed from the

crash recorder, but in any case, the program will be expensive. For

six million dollars one could equip 100,000 cars with crash recorders

that cost $60 each. It would also be possible to equip more cars with

a simpler, less costly crash recorder.

It is for others to determine the needed complexity of the crash

recorder. Perhaps it is not necessary to have a crash recorder that

records force time histories in three dimensions. Maybe vertical

accelerations can be sacrificed.

Perhaps it would also be useful to consider a “tri-level” crash

recorder program; this could involve a modest number of cars equipped

with a very complex recorder and a larger number of cars equipped with

a simpler, less expensive recorder system.

As a prelude to the program it might be appropriate to have a

research project to synthesize past laboratory crash data to try to

agree what measure in the field is the one that would account for the

most injury variance. Would it be impact speed, barrier equivalent

velocity, delta “v” or what?

The crash recorder, of course, is not the only need in studying and

understanding actual crashes. Much better and much larger collections

of highway crash cases

much reliance has been

tigated crashes. This

are also necessary. I stated my belief that too

placed on the small number of intensively invescountry needs a multi-state data collection

program which would accumulate records on 600,000 to 1,000,000 accidentinvolved vehicles per year. This would require three to five states the

size of North Carolina.

-35-
For a surprisingly small additional cost it would be possible to

collect that many cases with reasonably good deformation data, an

operationally defined injury scale, vehicle identification numbers,

belt usage, and various file linkage numbers to cross-link accident

data and driver history files, road data, etc. It is extremely

important to have this quantity of data in order to get timely answers

to questions. If a safety device has gone astray or a dangerous car

is coming onto the market--we need to know it soon--not after ten years.

I would be pleased at some future time to discuss some of the

characteristics such a multi-state data system should have.

-36-
APPENDIX D

SUMMARY OF REMARKS

AT THE

AUTOMOBILE COLLISION DATA WORKSHOP

Lawrence Patrick

Wayne State University

January 16, 1975

-37-
WAY N E S TAT E U N I V E R S I T Y

BIOMECHANICS RESEARCH CENTER DETROIT, MICHIGAN 48202

COLLEGE OF ENGINEERING TELEPHONE: (31 3) 577-3835

5050 ANTHONY WAYNE DRIVE

January 20, 1975

Mr. Howard Gates

Economics & Science Planning

1200 18th Street

N.W. Washington, D.C. 20036

SUBJECT: ESP Meeting, January 16 & 17, 1975

Dear Mr. Gates:

As requested at the captioned meeting, I am enclosing herewith

prints of the slides I used in my presentation together with a brief

summary of my remarks. In the interest of brevity, the remarks are

presented in outline form.

PREMISE

1. The only valid way to establish safety needs for automobiles

is through examination of field data.

2. The only valid way to evaluate the effectiveness of safety

measures is through analysis of their effect on accident data.

CONCLUSION

Accident data are essential.

CRITERIA FOR DATA COLLECTION

1. Sufficient data must be obtained for statistical analysis.

Collection of accident data is expensive so it must be optimized for

the number of variables, depth of study, and type of collision to

minimize the cost per accident. The present MDAI studies cost

approximately $2500.00 apiece, and include greater detail than is

necessary. With modification of the collection procedure accident

data in sufficient depth should be available at a cost of under $400.00

per case. Other data should be gathered on a large sample basis in

even less detail at a considerably lower cost.

2. Complete

Sex, age, weight,

important factors

of injury of each

and going through

injury data must be included in the accident data.

height, and general physical condition are all

in analyzing accident data. The type and degree

occupant including the minor bruises and abrasions

the severe bone and soft tissue damage are required.

It is important to have complete data on the restraint systems used

and the interior components of the vehicle that caused the injury.

-38-
Mr. Howard Gates

Economic & Science Planning

January 20, 1975

3. Complete vehicle crash data are essential to permit an

estimate of the collision severity. The crash data in addition

to the usual photograph should include measurements of vehicle

deformation. A standard means of recording deformation of the

vehicle would be beneficial.

4. Reference collisions are required to establish severity

of the accident from the crash data and deformation measurements.

Eventually the reference collisions and deformation data can

probably be replaced by a data recorder. The data recorder should

be relatively simple and the cost should be low enough to permit

installation in all vehicles. A crash severity signature is required

which gives crash severity in the most meaningful terms. This does

not necessarily require triaxial acceleration time histories. The

Barrier Equivalent Velocity that has been used extensively is not

necessarily the best measure of severity, but is one that has been

used extensively and should continue to be used until a better

measure of severity is developed.

DATA ANALYSIS

1. Standardized injury and deformation reporting is essential

to keep the results of investigations by different groups in different

parts of the country on a uniform basis. The AIS scale and the VDI

should be considered for the immediate future and utilized until a

better scale is devised.

2. The effect of sex, age, weight, size, position in vehicle,

direction of impact, restraint systems etc. should be established.

This will permit an accurate judgement to be made of the area of

safety improvement that should be stressed.

3. Probability of injury as a function of collision severity

is essential. It should be recognized that some individuals are

going to be injured severely at low severity clue to inherent

weaknesses. Fundamentally, it is necessary to protect the maximum

number of people from the maximum number of exposures. From a

design standpoint, it is essential to establish an acceptable

degree of injury under the most severe collision conditions. It is

recommended that the AIS-3 injury be the maximum acceptable injury

with no injury as the ultimate goal.

EXAMPLE: WSU-VOLVO STUDY

1. The WSU-VOLVO study was divided into four major divisions

as follows:

a. Accident Investigation - complete injury data including

the AIS rating and complete vehicle deformation

measurements.

-39-
Mr. Howard

Economic &

Gates

Science Planning

January 20, 1975

b. Staged Collisions - complete deformation data in

terms of impact speed.

co Simulation Tests - records of injury criteria as a

function of simulated speed.

d. Analysis - Injury data related to severity and test

data.

The accident investigation was conducted by the Volvo investigation

team with special instructions to meet the requirements of this study.

The staged collisions included frontal force, barrier, pole, and car

to car collision. The collision simulations were made in the

laboratory in a modified Volvo automobile with instrumented dummies

as the occupants using the same stopping distance and deceleration

pulse as measured from the staged collisions.

2. Accident criteria established to minimize the number of

variables include:

a.

b.

c.

d.

3. With

Frontal force collisions only.

Belted front seat occupants (one or more).

No unbelted rear seat passengers or other

heavy objects in the rear seat.

No external secondary impact of substantial

severity.

these stipulations, a total of 128 accidents were

investigated with 169 occupants in a two year period. During this

time there were eleven staged collisions at Volvo and 72 simulated

tests at Wayne.

4. Figure 1 is a plot of the injury as a function of Barrier

Equivalent Velocity with three injury areas for each occupant. As

noted from the legend, the data are divided into head, neck, and

chest injuries for each occupant with the driver and right front

passenger position differentiated. The figures at the bottom of

the graph refer to the number of body areas at each velocity for

which there were no injuries. It is important to note that AIS-3

injuries were found at velocities ranging from 10 to 53 mph with

the major number clustered at about 30 mph.

Figure 2 is a bar graph showing the distribution of injury

as a percent of the number of occupants in 10 mph increments. At

the O to 9 mph level approximately 90% of the occupants had no

injury and the remaining 10% sustained only minor injuries. In

the 50 to 59 mph range all occupants had some injury with one third

having the AIS-1 injury and two thirds having AIS-3 injury. It is

obvious that as the BEV increases the injury also increases.

-40-
Mr. Howard Gates

Economic & Science Planning

January 20, 1975

Figure 3 is a sketch of the rib cage with rib fractures and

sternum fractures illustrated. In the field study all of the rib

fractues occurred on the inboard side which is the side which the

belt applies the force to the ribs. The fractures have all been

put on one side although in the field there were fractures to the

driver and passenger and consequently they were on both the left

and the right side of the rib cage.

5. The accident investigating team carefully measured the

deformation of the vehicle at six different points on the front as

shown in Figure 4. A computer program was developed to record the

six deformation measurements in graphical form. Figure 5 shows the

deformation for the staged barrier collisions. These were all normal

frontal force collisions and consequently the deformation is symmetrical.

Figure 6 shows the same data obtained from the measuring fixture in the

field accident study. It will be noted that in this figure the impacts

are to poles and/or asymmetrical impacts which result in a different

pattern than the barrier results. It was necessary to interpolate

the field data to provide the closest BEV for the analysis. It is

felt that the overall barrier equivalent velocity assigned to each

collision is considerably more representative of the collision severity

than in previous studies.

6. Figure 7 shows the rib fractures for male and female as a

function of velocity. It should be noted that the age of the

occupant should be included as another variable. However, the

figure shows that the female has a greater number of ribs fractured

than the male.

7. Figure 8 is a graph of cumulative injury risk as a function

of abbreviated injury scale with velocity as a parameter. The data

are plotted for the 10 mph increments. The dash lines indicate that

the data are extrapolated with insufficient data for an exact

definition of the curve. However, the data show a distinct family

of curves. Additional data is required to delineate the curves with

greater accuracy. The same data are shown in Figure 9 with abbreviated

injury as a function of barrier equivalent velocity. This graph

permits an estimate of the likelihood of injury in a given frontal

force collision.

AMOUNT OF DATA REQUIRED

1. The collection of accident data requires a substantial amount

of data with extreme accuracy desirable but not necessary. For example,

there is no need to have a collision severity to within plus or minus

“one mile per hour”. This is especially true since we really don’t know

what the barrier equivalent velocity means or whether some completely

different severity index should be used. With the large number of

variables including impact velocity, impact direction, rigidity of

vehicle, rigidity of object struck, location of impact on car, occupant

location, occupant age, sex, height, weight, physical condition, tolerance

-41-
Mr. Howard Gates

Economic & Science Planning

January 20, 1975

to acceleration environment, posture, vehicle interior design, and

restraint systems, it is more important to have a substantial amount

of data with reasonable detail rather than a small number of cases

that have been investigated to a great depth.

2. With the large number of variables it is necessary to have

a large number of recorders in the vehicle population in order to

obtain a reasonable number of accidents with the recorders in the

car. The most desirable situation is one in which each car manufactured is equipped with a recorder installed at the factory.

CRASH RECORDER REQUIREMENTS

1. The crash recorder should be installed in a large number of

vehicles. Consequently, it must be low in cost.

2. The recorder does not have to be ultra-accurate (such as

plus and minus one percent on the acceleration and time scale), since

the analysis will be based on a large amount of data rather than a

small sample which would require the greater accuracy.

3. The crash recorder should be based upon a “severity index”

that has yet to be developed depending upon the injury potential to the

occupants. Such a recorder could be an integrating accelerometer with

electronics to perform necessary operations on the accelerometer output

to provide the severity index. Other means that might be satisfactory

include fracture of a number of elements in the accelerometer or the

deformation of an element in the accelerometer. The exact function

to be measured and the method of measuring it has to be developed.

4. The crash recorder should be developed in conjunction with

the data analysis group to insure maximum utility from the installation

of the recorder.

5. The recorder should be sealed to prevent tampering and to

guarantee that when the record is interpreted it has not been damaged

prior to being collected by the investigator. It should be designed

to give a record for a collision in excess of some predetermined

severity such as a 10 mph barrier equivalent or greater. This will

avoid the danger of having a recorder in multiple crashes which could

confuse the data or give false results. Obviously the recorder must

be rugged enough to withstand the collision without damage.

I believe that you or Dr. Goldmuntz requested a copy of my

curriculum vitae and list of publications. They are enclosed.

I thoroughly enjoyed the meeting on January 16th and 17th and

feel that it was productive in that I learned considerably from

it. Hopefully, the goals of the meeting will be achieved. Bob Cromack

has the preliminary writeup that we came up with during our working

-42-
Mr. Howard Gates

Economic & Science Planning

January 20, 1975

lunch on Friday. He is going to have it typed up and sent to the

rest of us (Brian O’Neill and David Morganstein). We will review

it and approve or modify it for final submission.

An invoice for my expenses is enclosed in accordance with our

agreement.

It was a pleasure to work with you on

be of any further assistance, please don’t

Sincerely,

this program. If I can

hesitate to call on me.

L. M. Patrick

Professor

LMP:ldd

ENCLOSURE

-43-
-14f - 01 -.

f-0

to

C90

In. .9 0*0m0N0

o000000:

E● >●

Id● m

a

Ii!

(4)

. 

-1.

31IS6

L?! I Al s

91 . 0

to

o

-44-
~

-— --

<aaaa

IJ

N

U

#o- m

I -.

—.~— —---- -

.

o

s

w

me

n

r4

(XM M MVAOA mznvwuoM) (%) Slv INvdn~~o do ~olln81~lsJ()

-45-
Driver .

Front Passenger

/

4

FIG. 3: ALL RIB AND STERNAL FRACTURES (WITH PASSENGER INJURIES TRANSFERRED

TO THE DRIVER'S SIDE)

-46-

~
Vertical

Horizontal

. I

\

. .

.

Left

Middle

Right

FIGURE 4 : DIAGRAM SHOWING MEASUREMENTS TAKEN WITH FRONT

END DEFORMATION FIXTURE.

-47-
—

VOLVO TEST VEHICLES

20, 30 AND 50 MPH

CM INCH

1 0 0

4 0

20

RL . CL LL ,

50 MPH

30 MPH

20 MPH

ORIGINAL

FIGURE 5: HOOD AND BUMPER DEFORMATION FROM STAGED

. FRONTAL BARRIER COLLISIONS.

-48-
80-

CM

100-

80

60

40

20

CM

100-

80-

60-

40-

20-

INCH CASE NO 6 1

.3-5

-39

INCH CASE NO 6 3

“35

-30

-25

-20

-10

‘FIGURE 6 : “ DEFORMATION DATA FROM EIGHT

.

6C40

.

20

OF

INCH CASE ND 6 0

‘\

-35

-30

INCH CASE NO 6 2

-35

-30

-25

-20

-15

r-- I

---i -

-- --- -

——.—

THE ACCIDENT CASES .

---

_49_
10

8

6

4

2

F. M.

● 0

■ o

Driver “

Front Passenger

o

0

.

0

0

0 10 2 0 3 0 4 0

BEV (mph)

50 60

FIGURE 7 : RIB FRACTURES FOR MALE AND FEMALE OCCUPANTS AS A

FUNCTION OF BARRIER EQUIVALENT VELOCITY.

-50-
a

7

100

8 0

6 0

4 0

2 0

0

0

●

I

I

I

I

\

\

\

\

I

\

\

\

\

\

.

0 I

!

2 3 4 5

ABBREVIATED INJURY SCALE–AIS

FIGURE 8: PERCENT OF CUMULATIVE INJURIES, EQUAL TO OR

GREATER THAN, A GIVEN AIS LEVEL FOR 10 MPH

INCREMENTS .

-51-

-
3

2

I

o — — .

o 10 20 30 4 0

3

2

I

o

50 60

BARRIER EQUIVALENT VELOCITY — B E V

FIGURE 9 : INJURY AS A FUNCTION OF BARRIER EQUIVALENT

VELOCITY FOR CUMULATIVE PER CENT OF INJURY

-52-

——.— .— . . . .
APPENDIX E

LETTER FROM RICHARD WILSON

GENERAL MOTORS CORPORATION

February 4, 1975

-53-
February 4, 1975

Dr. Lawrence A. Goldmuntz

Economics and Science Planning

1200 18th Street, N.W.

Washington, D.C. 20036

Dear Dr. Goldmuntz:

You are to be complimented on your recent Automobile Collision Data

Workshop. The free interchange of ideas from such a wide cross-section

of data gatherers and data users should be most useful as you formulate

your recommendations to the Office of Technology Assessment. I was

happy to participate and hope the following comments and the attached

material will add to your study.

GM believes there is a need for better accident data so that the true

benefits of safety standards can be assessed along with their cost of

implementation. This applies to current standards just as well as it

does when considering future rulemaking. The value of better data is to

improve vehicle safety and to decrease the risk of making an incorrect

decision on a standard. The incorrect decision may result in enacting

or failing to rescind a standard which is not cost beneficial, or, on

the other hand, rescinding or failing to enact a cost beneficial standard.

NHTSA should move ahead only with those standards on which they have

sufficient information to support a favorable benefit/cost relationship.

You specifically asked for an estimate of the “potential societal cost

of not having better accident data”. One way to look at this is to

consider that the cumulative cost to the consumer for safety standards

to date is estimated to be approximately $245 per car (exclusive of bumper

provisions). An additional $250 per car are forecast if proposed new

safety standards take effect. This $495 per car total related to current and

proposed safety standards (bumper standards would be a further addition)

translates to about $5 billion per year if applied to production rates

of 10 million cars per year. The need for reliable benefit data against

which these costs can be evaluated is urgent. Accident data is one source

for such information.

Basic requirements for a better accident data system have been presented

before. GM has discussed NADS* and the University of

Safety Research Institute has presented SIR**. Other

* National Accident Data System - Paper by Terry and

Michigan Highway

plans may be

Schneider given

at GM’s June 1973 Automotive Safety Engineering Seminar (copy attached).

** National System for Collecting Multipurpose Accident Data - paper by

O’Day given at the June 1974 Experimental Safety Vehicle Conference.

-54-
forthcoming from your workshop. While exact data system costs have

not been formally worked out, they likely are in the area of 10 to

20 million dollars a year. If better accident data could increase

the benefit/cost of safety standards by even a few percent (one

percent of the above $5 billion would represent $50 million), the

$10 to $20 million government investment per year seems very reasonable.

As a specific example, we estimate the cost of continued use of side

guard beams, needed to meet MVSS 214, to be about $10 to $12 per car.

Applying this cost to 10 million cars per year, this single item of

standard represents a total amount to the consumer of $100 to $120

million per year. And yet, the current state of accident data does

not even allow a determination of whether side guard beams have had

any benefit or not. Again, $10 to $20 million per year for better

data seems a minimum expenditure when viewed as a critical ingredient

guiding the public’s investment of billions of dollars in the costs

of their cars.

I hope your project will pull together our country’s need in the

accident data area. We are convinced there is a need for this type

of better decision-making information. I look forward to your

final report.

Very truly yours,

R. A. Wilson

Engineer-in-Charge

RAW/clw

Attach.

-55-
National Accident Data System

C. Thomas Terry – Section Engineer

Richard W. Schneider – Senior Project Engineer

Safety R & D Laboratory

GM Environmental Activities Staff

Field accident data which reflect what is truly happening m

the field today are necessary (1) for the automobile industry

to evaluate performance and guide future designs and (2) for

the NHTSA to evaluate standards and guide future rule

making. This type of data system is not available now. The

multilevel system recommended by GM to accomplish this

would use the expertise already available in many of the

NHSTA-Sponsored multidisciplinary accident investigation

teams. The system consists of several study areas which

include exposure data and levels 1, 2 and 3 accident data.

Another requirement of the system would be a central facility

which would process the data and make it available to both

NHTSA and industry.

On June 12, 1970, at a Data Accident Investigation

workshop* in Brussels, Belgium, GM outlined why field

accident data is needed by automobile manufacturers. These

needs to collect accident data are:

Data Needs

1. Evaluate present safety system% ,

2. Predict performance of proposed safety systems.

3. Identify problem areas & evaluate solutions on

cost/benefit basis.

4. Estimate human tolerances to impact

1. Evaluation of Production Safety Systems

Early accident investigators saw the results of automobile accidents and identified those vehicle components

which were producing frequent and severe types of trauma.

This early work supported the introduction of items such as

the high penetration resistance (HPR) windshield in 1966 and

energy absorbing steering columns in 1967. These investigators

were able to measure the relatively large performance

improvements of those safety systems. More subtle changes in

safety performance can be found only by data collection

programs that are refined enough to exhibit statistical trends.

For example, it is generally agreed that further changes made

to the present windshield will result in a smaller improvement

in injury reduction compared to that made in 1966. Measuring

this potential change in performance will require a

sophisticated accident data collection program.

2. Prediction of Proposed Safety Systems

Before implementing any change to safety systems already in

the field, the performance of the new safety systems must be

predicted. This is the second principle way in which accident

data is used.

If the prototype safety system is an improvement on a

production item such as the current windshield, then the field

data gathered in evaluating the current windshield’s

performance is used as the injury pattern baseline. The

modified system is then tested in the laboratory to compare its

performance with the present system. This laboratory

comparison provides data to subjectively project how the new

windshield might modify the present injury pattern in the

field. In this way, the prediction can be made with some

confidence as to the performance in the field of the proposed

new system.

If a completely new safety system, such as the air cushion

restraint system is proposed, the injury patterns which the new

system could somehow influence must be identified. In the

case of the air cushion restraint, available accident data might

be used to identify the injury patterns in frontal collisions

where the air cushion is envisioned to be most useful. The air

cushion’s effectiveness, as determined from laboratory tests,

could then be used to predict how the present injury patterns

could be modified by the introduction of this new restraint

system.

3. Identification of Problem Areas and Evacuation of

Proposed Solutions on a Cost/Benefit Basis

This identification of problem areas requires an over-view of

the total injury picture. The over-view consists of the

frequency of particular injuries caused by various components

and the severities of these injuries. The areas where the most

improvement can and should be made are generally where the

highest frequency of most severe injuries occur. A relationship

between frequency and severity should indicate the areas of

high payoff – those areas where the most good can be done.

Once these high payoff areas are identified, the priorities of

safety development can be established by cost/benefit studies.

As solutions to the more obvious problem areas are incorporated, the identification of the less obvious problem areas

becomes more difficult. To identify the less obvious problem

areas will require incorporating even more rigorous data

collection programs. It may be possible that a point of

diminishing returns will be reached. That is, the time and cost

of acquiring even more detailed information may not justify

the insignificant amount of improvement made from the data

derived. To reach this point is a noble goal indeed.

* R. A. Wilson & C.T. Terry, NATO . . Accident Investigation

Workshop , FIELD ACCIDENT RESEARCH – GM’s

APPROACH, unpublished presentation, Brussels, Belgium,

June 12, 1970 .

-56- 
4. Estimation of Human Tolerances to Impact

The three uses of the field accident data discussed above are

specifically aimed at changing the design of the vehicle to

reduce the frequency and severity of injuries. A different use

of the data is to isolate particular accident situations so that

information concerning human tolerances to impact can be

generated.

Occasionally, from a large source of accident data, a particular

occupant injury in a well-defined automobile accident

situation can be attributed to a particular vehicle component.

When this infrequent situation arises, and the mechanism of

injury is understood, correlation of the accident or “field

experiment” with a similar laboratory experiment is

attempted. If the “field experiment” can be correlated to the

laboratory, the occupant’s impact situation might be

quantified and the human tolerance to a particular type of

trauma can be estimated. For example, an instrument panel

may be identified as the cause of a particular type of head

injury, A series of similar instrument panels are impacted in

the laboratory until the damage to the instrument panel in the

accident case is reproduced. The forces and accelerations to

produce the damage in the laboratory are then correlated to

the injury produced in the field, In this way, the human

tolerance is quantified for this particular type of injury.

These needs remain as valid today as they did three years ago.

Further mentioned were the qualities of a good field accident

data system:

Data Qualities

1. Rapid feedback

2. Random data sample

3. Current model data

4. Data compatibility

1. Rapid Feedback

A prime goal in automotive safety is the reduction of injuries

and deaths due to automobile accidents. The more injuries

prevented and lives saved, the better the job is done. improved

safety systems must be incorporated as rapidly as practicable

to achieve this goal. An orderly implementation of improved

safety systems depends in large measure on the collection and

assessment of field accident data. Only after a sufficient

amount of statistical and in-depth data is collected can

problem areas be identified and further improvements be

recommended and implemented.

2. Random Data Sample

Besides the quantity of data gathered, a random sample is

essential to insure its quality. Basically, random data is needed

so that conclusions aren’t erroneously based on the

consequences of a unique accident, or limited number of

accidents. False accident and injury patterns can be created by

generalizing from a small sample of non-random cases. In the

past, most sources of accident data have not been random.

Most accident investigations typically have been biased by

geography, injury level, damage level, or other accident

selection techniques. A valid data sample must be

representative of the real world.

3. Current Model Vehicles

Each year safer automobiles are produced. Measuring these

advances in safety performance from one year to the next

requires a valid data baseline. it should be realized that

resources are limited and it would be virtually impossible to

collect enough data on the total vehicle population in one

year. The most efficient use of resources is to concentrate

investigation on the most useful data source - current model

vehicles. Of course, as current model data is collected each

year, in time, a data bank will be built which will allow a

comparison of newer automobiles with trends based on many

years.

4. Compatibility of Format .

If various data sources are ever to be combined to form large

data banks, they must, at least, be in the same basic format.

This means that the same information is recorded for each

accident and some means of easily combining information

from different sources is provided. This is particularly

important when in-depth data is being collected because of its

inherent complexity.

However, even when it is physically possible to combine data

from various sources, it is not always advisable. Each

investigator tends to bias his accident selection in some

manner such as injury only, rural only, etc. Since the data base

for each investigator is usually different, a direct statistical

comparison of their data is not advisable.

Again, these characteristics are still desirable today as they

were three years ago. There is no known source today which

satisfies all of these qualities. The one key quality which bears

emphasis is the random data sample. The random data sample

criteria implies that the accident cases selected are

representative of the national accident experience. This

representativeness is critical for sound decision making

regarding automobile design and government rule making.

-57-
Making decisions with national implications in highway safety

using only data from rollover accidents in North Carolina is no

more valid than predicting the Gross National Product from

monitoring only the construction industry in Utah.

Current Data Status

In the three years since that NATO workshop, some other

factors have become obvious regarding the value of accident

investigation.

1.

2.

.

The information received not only can be used by the

industry for evaluation and direction, but also can apply

to Government at all levels for rule making.

Variation in the interpretation of current accident data

results from two factors:

a. Different analysis techniques

b. Different data sources

Variation of results due to the first cause i.e., different analysis

techniques, is healthy and promotes various problem solving

strategies to be explored and compared. However, differences

due to the second source are generally inefficient and result in

problems of interpretation. This problem will remain unsolved

until the many various data collection efforts are coordinated

so that their results can be combined. This combination into a

representative data set will then allow, the safety experts to

base decisions on a sound technical basis.

These previously stated needs and system characteristics

coupled with the conflicting conclusions which result from the

uncoordinated data collection activities around the country

have led GM to propose what is called a National Accident

Data System.

Before outlining the proposal for such a system, one point

should be stressed: the system being proposed is not the best

system that theoretically could be designed. In fact, it is

several steps away from being an optimum design. But it is also

many steps closer to an optimum system than anything that

exists today. Rather than wait for that perfect system to be

implemented, it is imperative that the obvious contradictory

nature of various data sources be eliminated now so that valid

cost/benefit studies can be used in achieving the goal of

reducing injury and death on the highway. Each change made

to the system after it is begun should be directed toward the

desired optimal system.

The proposal itself tries to incorporate many of the data

collection activities that are now in existence while eliminating

other unnecessary ones. But the design is primarily dictated by

the desire to establish a coordinated National Accident Data

System in a relatively short period of time.

DATA COLLECTION

The proposed system involves designating certain geographic

regions of the country as sample areas where extensive

surveying and profiling will be conducted. This is analogous to

taking a Gallup Poll of the nationwide accident experience.

Since many of the existing Multidisciplinary Accident

Investigation (MDAI) teams sponsored by the NHTSA are

somewhat randomly located and because expertise already is

available from the teams, we are proposing that selected MDAI

teams would form the nucleus for the data collection system.

This proposal would convert existing MDAI teams into

multi-level programs such that each team has the responsibility

of coordinating the gathering of the following

information within their specific regions:

1. Exposure data (non-accident)

2. Level 1 accident data

3. Level 11 accident data

4. Special accident studies

Teams which could not reliably supply all these

information would not be included in this program.

Exposure Data

Exposure data is profile information on the number

levels of

levels of

and types

of people, vehicles and roads in the area. this information is

used to define the universe in which the accidents are

recorded. Ideally, when all the regions are combined, the

exposure should be “representative” of the total United

States. Capturing data of this nature allows the various

combinations of vehicles/drivers/roads to be described whether

in an accident or not. Most of this information is available in

existing state operational files. The system should allow

specific surveys of additional data to also be conducted. For

example, it may be necessary to establish how many miles

various age groups drive annually.

Level I Accident Data

This level requires collecting a standard police report on all

accidents in the region which meet a predetermined severity

threshold. An alternate to the standard form would be a form

with a common core of information with other elements

decided upon by the local jurisdictions. This level of

information briefly defines the nature of all accidents in the

area. This information, coupled with the exposure data, make

possible the computation of accident rates, such as

-58 -
fatalities/miles driven, accidents/make and model, or

accident/driver age. Since the accidents described in this file

contain both injury and no-injury cases, computing the

probability of an injury occurring is also possible. Definitions

or specifications of variables within each region and from

region to region must be consistent. This standardization of

definitions between regions is imperative, and will provide the

program with one of its greatest challenges and one of its

greatest advantages over current programs Emphasis upon the

training of the police investigation people is important for this

level of data. Definition of what an accident is or of what the

various injury levels are must be explicitly stated and

uniformly interpreted. Again, flexibility should allow specific,

supplemental information to be collected when needed. As an

example, the police could be asked to ascertain whether the

head restraint was in the “up” or “down” position in a rear

end accident.

Level II Accident Data

This level of data would collect information on all

accidents in the region which involve a recent model

vehicle and an injury. Information on all vehicles involved

in the accident would be required. The injury may in fact

occur in an older vehicle which impacted the

recent model vehicle. This level data has been most valuable

from the manufacturer’s viewpoint and has historically been

the source of injury causation information. Extending the

coverage to include older vehicles would allow comparison of

vehicles of different ages. in the past, information of this type

collected by GM and other has led to improved vehicle design,

examples being HPR windshields and the energy absorbing

steering assembly. The information gathered would define the

injury severity, the causes of the injury, the accident

description, a measure of its severity, and some information

relative to the cause of the accident. This information will

allow the assessment of new safety systems as they are

introduced such as air cushion restraint or starter-interlock

webbing systems. Gathering the data on all accident modes

and injuries will allow relevant safety evaluation tests to be

specified. By combining this data with the Level I Accident

Data, it may be possible to evaluate the relative safety

performance of various makes and models of vehicles. The

current thinking is that the information would be gathered on

a modified version of the GM Field Form by investigators

working for the MDAI teams. As with the present Field Form,

a series of photographs will be required to supplement the

information. The form would be expanded to collect

information on pre-crash and post-crash phases of the accident

which are not presently addressed on our existing form. This

part of the system would also allow extra information to be

collected on items of specific interest which are not in the GM

Field Form. For example, the investigators may be asked to

see if the starter interlock system has been defeated or if it had

any effect on the occupant’s usage.

Level Ill Accident Data

These special studies are performed to see why particular

problem areas exist. The special studies conducted are based

on the Level I or Level [1 information already gathered. For

example, a special investigation could be undertaken to more

closely examine why a particular class of vehicles for

“over-represented” in a particular type of accident. The

investigation may find that this type of vehicle is popular for

owner modification which could result in unstable handling

characteristics.

DATA COMPILATION

The next logical question is what to do with the data after it is

collected in its relatively rough form i.e., police reports, GM

Field Form, and photographs. TO keep the interpretation of

raw data consistent from area to area, it is proposed that the

data be collected in a central location. At this location, the

Level I data would be entered directly into a data bank. The

information from the detailed Field Form and photographs in

the Level II system would be analyzed and the final

information entered into an automated data system. By

centralizing this function, the number of subjective judgments

are made more or less to be consistent because of the relatively

few number of people involved. This situation is similar to that

which is now used with the General Motors-MIC program, and

has been found to be quite satisfactory. We feel the overall

quality of data will be enhanced by increasing the consistency

of the data. This central facility would not only provide

common data entry and storage facilities, but would also offer

a retrieval system for interested data users.

PROGRAM IMPLEMENTATION

Since this program should benefit the industry as well

as the Government, it is recommended that joint

Government/industry support for the implementation and

annual operation of this program be solicited. The industry

support could logically be under the auspices of either MVMA

or SAE. Specifically, it is felt that the program offers a great

opportunity for joint efforts between Government and the

industry toward achieving a common goal. There are actions

required of both industry and government to implement the

proposed program. The program is a national goal and

therefore should be funded with Federal monies. However, the

●

-59 -
industry should be willing to participate in initiating the

program and continue support to the end that the data will be

valid and available.

After this program is initiated, data acquisition could begin in

less than a year. As shown in Figure 1.

ACTION S

INITIATE

PROGRAM

COLLECT

DATA

DEFINE DESIRED SAMPLE

ANALYZE MDAI AREAS

CAPTURE LOCAL AUTHORITIES

DESIGN DATA COLLECTION SYSTEM

SELECT AND TRAIN MDAI TEAMS (Level Ill)

TRAIN LOCAL AUTHORITIES (Level I)

TRAIN ACCIDENT INVESTIGATORS (Level II)

.

MONTHS

Figure 1

SUMMARY

Although this system is not a new idea, it is the basic

simplicity which is most appealing. The program has been

outlined in general terms only, although it has been given

much more detailed thought as this general outline was

developed. Rather than explore the details at this time,

support is being solicited for the overall plan of action in the

hope of gaining cooperation from other groups in the detailed

planning phases of the program. Again, the payoff from such a

system would be high, and achievable in a relatively short

period of time.

It is GM’s intent to act as a catalyst in the design and

implementation of a National Accident Data System and

encourage any of you today to accept this challenge with us.

C. Thomas Terry

C. Thomas Terry is a Section Engineer responsible for the

Field Accident Research activity at the safety Research and

Development Laboratory located at the GM Proving Ground.

His responsibilities include the collection and analysis of field

accident data

He received a Bachelor of Science Degree in Civil Engineering

from Rose Polytechnic Institute, Terre Haute, Indiana, and a

Master of Science in Engineering Mechanics from Wayne State

University, Detroit, Michigan. Mr. Terry joined General Motors

in 1969 and was assigned to the biomechanics area with

responsibilities in human simulation and volunteer testing. He

was chairman of the SAE Crash Test Dummy Subcommittee

during this time.

Mr. Terry then joined the Field Accident Research group in

1970 and was promoted to his present position in 1971. In

1972 he assumed the role of Chairman of the Motor Vehicle

Manufacturers Data Collection Co-ordinating Subcommittee.

Among his publications are:

“Radiological Studies of Organ Displacement Due to

Vertical Accelerations ” presented at the 18th Annual

Conference of Engineering in Medicine and Biology,

November 1965, Philadelphia, Pennsylvania.

“Review of Mathematical Models of Response to

Acceleration, ” presented at the Winter Annual Meeting of

the American Society of Mechanical Engineers, November

1966, New York, New York.

“A viscoelastic Model of the Human Spine Subjected to +gz

Accelerations, ” Journal of Biomechanics, Vol. 1, pp

161-168, Pergamon Press.

“Field Accident Research–GM’s Approach, ” R. A. Wilson,

C. T. Terry, presented at NATO Accident Investigation

Workshop, Brussels, Belgium, June 12, 1970.

“Benefits of the In-Depth Case Study, ” presented at 1972

Annual Meeting of Society of Automotive Engineers,

January 10-14, 1972.

“National Accident Data System, ” C. T. Terry, R. W.

Schneider, GM Automotive Safety Seminar, June 2&21,

1973.

Richard W. Schneider

Richard W. Schneider graduated from Grinnell College where

he received the degree of B.A. in 1969 and a Masters Degree of

Business Administration in 1971. He joined General Motors

Proving Ground in 1971 where he was involved with field

accident research. Mr. Schneider is currently senior project

engineer with the Safety Research and Development

Laboratory at the Proving Ground and active in the area of

field accident research. He is a member of Operations Research

Society of America.

-60 -
APPENDIX F

STATISTICAL RATIONALE FOR THE

NUMBER OF AUTOMOBILE CRASH RECORDERS

PROPOSED FOR PROCUREMENT AND INSTALLATION BY NHTSA

National Highway Traffic Safety Administration

February 5, 1975

(date of receipt)

-61-
STATISTICAL RATIONALE FOR THE NUMBER OF AUTOMOBILE CRASH RECORDERS

PROPOSED FOR PROCUREMENT AND INSTALLATION BY NHTSA

National Highway Traffic Safety Administration

(Received February 5, 1975)

The statistical justification for the number of crash recorders

requested by NHTSA depends primarily on the answers to two general

questions.

A. If N crash recorders are installed in passenger cars, what

number of crashes will be recorded annually in each category ,

or "cell" of interest? For example, how many frontal impacts

with impact speed (AV) 30 mph or more will be recorded by

the crash recorders?

B. Given the answers to question A, will these numbers provide

adequate information on the crash environment. This involves

statements about the precision and accuracy of various estimates

of rates, proportions or distributions, such as confidence limits

or error standard deviations.

Figure 1 summarizes much of the basic factual information needed

to answer question A. The figure shows numbers of crashes of various

types that would be expected in 1 year from a crash recorder fleet

of 100,000 vehicles. The numbers are derived from NHTSA's experience

with the current restraint systems study and other accident studies.

The estimated recovery rate for crash recorders in accidents is 64

percent; this is a judgment factor on which there are few relevant data.

-62- “
Figure 1 shows an initial fleet of 100,000 recorders, and it is

easy to modify the figure to obtain two other useful sets of figures.

If one adds three zeros to each number in the figure, the resulting

numbers are estimates of the numbers

entire U.S.-automobile population in

each divided

For example,

year will be

recovered.

Figure 2

distribution

by 1,000, the result is

of crashes occurring with the

1 year. If the numbers are

the percent in each category.

we can see that about 1.6 percent of the vehicles each

involved in towaway crashes from which the recorder is

illustrates the problem of estimating the cumulative

of crash speeds. (“Speed” may refer to any measured value

such as Av, barrier equivalent velocity (BEV), traveling speed, etc.).

The figure shows a “true” distribution function, represented by the

solid curve, and an empirical distribution, obtained through the

recorder, and represented by the stepped graph. The maximum vertical

distance D between the two curves is a random variable. As the number

of observations increases, the probability that D will exceed any

specified value decreases; i.e., the empirical distribution function

approaches the true population distribution function. The following

table shows the numbers of observations needed to obtain 80. and 90-

percent confidence that the maximum deviation between true and

empirical distribution functions does not exceed a specified value.

-63-
Figure 1 - Yield from 100,000 Crash Recorders in 1 Year

I

Crash Recorder Fleet

100,000 Vehicles

Police Reported Crashes

8,000

I

Towaways

2,500

*

?

Recorders Recovered

1,600

& i i

“(3)

(4) ‘

I

AIS=6

Fatal

Injury

17

(1)

(6)

-64 -
Figure 2 Cumulative

●

Distribution of Crash

PERCENT

100

75

50

25

0

20 40 60 80 100

SPEED, MPH

-65 -
Table 1. Number of Observations

Required for Specified Confidence

That Maximum Deviation Between

Empirical and Hypothetical

Distribution Does Not Exceed ●

Value Shown

Maximum

Deviation

.01

.02

.03

.04

.05

.08

.10

Confidence Level

80 Percent

11,449

2,862

1,272

716

458

179

115

90 Percent

14,884

3,721

1,653

931

595

233

. 150

-66-
.

In estimating the fraction of the crashes that fall into a category

of interest (e.g., impact speed over 30 mph), we are concerned with the

variability of an observed proportion f in a sample from a population

in which the “true” proportion is p. In large samples (> 25) the

observed fraction is distributed normally with mean p and standard

where n is the sample size. The greatest variability occurs when p = .5,

in which case the formula reduces to

So if we specify a probability (confidence level) that the observed

results shall not deviate by more than D from the population proportion p,

the required sample size can be estimated. Table 2 shows maximum sample

sizes required at two confidence levels.

.

-67- ,
Table 2. Sample Size Required

to Estimate a Proportion with

Error Less Than D

Maximum Deviation D

From Population

Proportion

,01.

.02

.03

.04

.05

.08

.10

Confidence Level

80 Percent

.4,107

1,027

456

207

164

84

41

90, Percent

4

6,767

1,692

752

423

231

106

58

-68 -
The preceding material will now be applied to let us reach some

conclusions on how many crash recorders NHTSA should purchase and

install. .

1. To estimate the proportion of fatal crashes at barrier

equivalent velocity below a stated speed, close to a million

recorders would be needed. From line (6) of Figure 1, we see

that these would yield 170 frontal impact fatalities in a year

and 510 in 3 years. This would permit us to state, for example

with 80-per cent confidence, “the percent of fatalities in frontal

impacts in which BEV exceeds a stated speed is x ±3 percent”

after 3 years of data collection with 1,000,000 recorders. For

deaths in crashes other than frontal, the requirements range from

at least six times as great for side crashes to at most 24 times

as great (i.e., 24,000,000) for rollover crashes. The costs to

determine any of these fatality distributions directly with the

crash recorder appear to be prohibitive.

if we use the injury criterion of either fatal or severe injury .

(AIS > 3), (see line 6, Figure 1) the required numbers reduce by a .

factor of approximately 4, but are still very high.

2. A more limited goal is to determine the distribution of barrier

equivalent speeds in crashes by impact type. This information is an

essential input for crashworthiness design. In this case, the distribution

of BEV's for frontal crashes can be determined quite well in a year to

about ±.03 with 100,000 recorders> The error in estimating a single

proportion (for example, the fraction of BEV under 30 mph) will be less

-69-
●

than .02 with 80

confidence. For

estimated within

percent confidence and less than .03 with 90-percent

side and rear impacts, the BEV distribution can be

±.80 with 85-percent confidence.

3. Table 1 shows that to reach 80-percent confidence that the

,

distribution of impact speeds observed with a crash recorder is within

±.03 of the “true” distribution function of observed population of -

.

* ,

crashes, it is necessary to record 1,272 crashes. .

The number of recorders needed to be sure of 1,272 recordings - .

depends upon the frequency of the crash type that is of interest.

The following table shows the number needed for several crash types

of interest. These numbers assure us at the 80-percent confidence level

that the maximum error does not exceed ±.03.

Impact Direction Severity Level 1 Year 3 Years

Frontal

Frontal

Frontal

Side

Rear

Rollover

Fatal

AIS > 3 

Towaway

Towaway

Towaway

Towaway

7,490,000

1,960,000

106,000

636,000

849,000

2,546,000

2,500,000

653,000

35,000

212,000

283,000

852,000

4. Another goal of the crash recorder program is to “calibrate”

other measures of crash severity. Some cheaper, less accurate, even

biased measurements may become very useful if their biases are

consistent and if we can estimate their error distributions. For

example, we might use vehicle deformation more readily if we know how

-70-
to associate a speed with each point on the vehicle damage scale and

could determine the expected errors. The situation is analogous to

using a ruler that is 1 inch too long. If we knew the “true” values

corresponding to the erroneous ones given by the ruler, we would be

able to use the ruler and make corrections.

To accomplish this calibration it would be necessary to consider

separately vehicles whose deformation characteristics differ substantially.

A minimum of four groups would be required, corresponding to various

classes of vehicles. Additionally, it is necessary to consider the

type of object struck: soft or hard, concentrated or distributed. .

Finally, the calibration needs to be done for at least five points on

a speed curve, preferably more. There could be a requirement for up

to 80 groups of observations or cells (4x4x5).

With a fleet of 100,000 crash recorders, NHTSA could obtain 1,200

frontal crash impact recordings in a year, which is an average of

1,200 ÷ 80 = 15 per group, and many groups would have much less than 15

observations. Over a period of 3 years the average group size would

reach 45. If one assumes a 5 mph standard deviation for the inaccurate

measurements, then with 15 measurements the mean for each measured point

on a speed curve will be determined with 90-percent confidence to within

1.3 mph. For a 10 mph standard deviation in the measurements to be

calibrated, the 90-percent limits will lie 12.5 mph from the mean.

.

-71 -
Conclusions:

1. Installing 100,000 recorders would permit a reasonably accurate

determination of impact speeds for frontal towaway crashes in a year’s

time. Less accurate determinations of side and rear crash speed distributions for towaways would be available by the end of 3 years. These

statements rest on the assumptions that:

(a) The energy crisis and 55 mph speed limit will not reduce

the rate of crashes drastically.

(b) NHTSA can find a way to get a representative sample of

crashes.

2. With 100,000 recorders, it will be possible to “calibrate” the

various proxy measures used by accident investigators with an acceptable

degree of accuracy.

3. The recorder program does help provide a basis for rulemaking.

The NHTSA rulemaking organization was quite clear in the requirement for

data which only recorders can provide. Attached are 4 charts which

state the application of recorder data. The standard writers have

consistently provided positive support to the recorder program because

of the additional dimensions they provide the technical data base upon

which standards are based.

-72 -
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-76 -
APPENDIX G

CRASH RECORDERS

AND

ALTERNATE METHODS OF DEFINING CRASH SEVERITY

James O'Day

HIGHWAY SAFETY RESEARCH INSTITUTE

University of Michigan

February 8, 1975

(date of receipt)

-77 -
Crash Recorders and Alternative Methods of

Defining Crash Severity

James O'Day, Highway Safety Research Institute, university of Michigan

Received February 8, 1975

Precise and representative data on highway crashes in the

United States have potential value in enactment of standards,

design of new vehicles, and in the evaluation of recent safety

improvements. Accident data collected to date have been intended

to serve many purposes, and one of the consequences of such a

multipurpose activity is that it may not solve any specific problem

as well or as economically as would an experiment designed

specifically for one purpose. . .

One of the measures desired by many concerning the U.S.

fatal accident population is the cumulative distribution of

fatalities by crash severity. This has frequently been put in

the form shown in Figure 1 with the abscissa being a barrier

equivalent speed. It is clear that if we knew the exact crash

speed (defined in an understandable and meaningful way) for each

fatal crash in the U.S. for, say, one calendar year, the curve ‘

plotted from that data would precisely define the population. If

we could sample randomly within the same population we could

define this curve with a degree of precision which depended on

the sample size.

The crash recorders which have been proposed for installation

are, of course, not capable of infinite precision nor do they

necessarily report the barrier equivalent speed used in the wording

of the standard. The test sequences in controlled crash tests

reported indicate a 95% error of less than 2 miles per hour in

the derived velocity change (AV). The sample size required to

achieve a precision in the vertical scale to that in the horizontal

scale may be computed from a knowledge of the slope using the

Kolmogorov-Smirnof test. For large numbers of cases (N >100)

the error in percent (95% bound) may be computed from:

-78-
For a 2 mph error in /JV, and a slope of the distribution

of approximately 2.5 (percent/mph) the required sample size would”

be 740 cases. There would be some gain, of course, in an infinite

sample; but a more usual practice would be to define the sample

size as above so as to increase the total error only by the square

root of two.

SAMPLING CONS1DERATIONS: “

In order for the data for a sample to truly represent the

national population, the sample must be properly drawn. If there

is a bias in the sample, the output will not be representative.

For example, if the mean age of the fatal occupants in the sample

were ten years older than the mean age in the U.S. vehicle fatal

population-- and with the assumption that 10 years of age were

equivalent to 5 miles per hour in fatality probability, the curve

of Figure 1 would exhibit a bias Of the order of 12.5% in a downward direction. There are, of course, a number of other possible

biasing factors. If all cars in the sampled group were full size

(and the total population contained a large proportion of small

cars) the distribution would be affected in the opposite direction.

The biases given as examples here are estimates for illustration

only, but they are not unreasonable. To get the true representation

one must either sample in such a way as to eliminate the biases

(e.g., random sampling) or collect enough additional information

to adjust the data to correct for unwanted bias.

NUMBER OF INSTALLATIONS NECESSARY FOR 740 FATAL CASES

There are a number of ways of computing the number of installations necessary to compile 740 fatal crashes over some period

of time. A simple one will be used here. With approximately

100,OOO,OOO passenger cars in the U.S. and about 40,000 in-car

fatalities per year, only one in 2500 passenger cars would have

a fatality in it in a year. 740 fatalities, then, would require

-79-
1,865,000 installations. If a three year period were acceptable

this reduces to approximately 622,000 installations. If a

larger error were acceptable (say twice as large), we no longer

need 740 fatalities but only 1/4 that number--and the sample could

be further reduced to 155,000. So in three years with 155,000

installations there is a potential for defining the desired

cumulative curve with a precision on the order of ± 10%. The

various options are shown in graphical form in Figure 2.

DIS CUS S ION

The statistical considerations above are based on a precise

and complete sample. The mechanics of achieving this are not

trivial. Placing a number of recorders in a sample of new cars

biases the sample against older cars in the general population.

And if these new cars were then distributed to the general population a high percentage of recovery would be difficult if not

unlikely.

Placing the devices in a fleet (for example by agreement

with an insurance company) should increase the probability of

recovery--perhaps to a very high value. But this same action

is likely to result in a non-representative sample in terms of

age, sex, or car size. Adjusting such data to draw inferences

to the national population is a questionable practice.

ALTERNATIVES

A number of crash severity measures can be viewed as alternatives to the crash recorder. None have the advantage of producing a direct acceleration-time trace during impact. But most

are applicable in principle to all cars. These include the CDC

 (Collision Deformation Classification) --a newer version of the

VDI (Vehicle Damage Index), the SMAC computer programs developed

by the CALSPAN Corporation, comparison of detailed crush measure-

-80-
ments on accident involved vehicles with results of instrumented

crash tests (as described by Campbell in SAE paper 740565) or

by Patrick (in an analysis of Volvo crashes). In addition, the

TAD scale as applied by several police agencies is a crude measure

of crash severity with the potential for relatively universal

employment. Each of these will be discussed briefly below.

The CDC (or VDI)

The CDC was developed as a means of recording crash damage

in a simple codable form. It consists of 6 elements--the clock

direction of impact, four letter codes indicating the location of

the damage (vertically and horizontally) and the general nature

of the object struck, and a numeric code (1 through

the extent of deformation. An experiment conducted

at Southwest Research Institute, and reported in an

indicates that the CDC as presently defined can, in

7) indicating

by Cromack

SAE paper,

general, be

assigned consistently by a trained investigator. The CDC, however,

is not directly convertible into a measure of the crash dynamics

because it depends in part on the structural characteristics of

the particular car under investigation. Further, it was not

developed primarily as a substitute for a measurement of the

deceleration characteristics of the crashed vehicle, but rather

as a simple codable record of crash damage.

The data elements contained in the CDC, however, when related

to a knowledge of the vehicle structure (and perhaps other information about the crash circumstances) could permit a computation

of some of the crash dynamics. An experiment could be conducted

(largely with existing data) to define the ability of the CDC

to predict much of the output desired from crash recorders. If

an initial experiment looks promising, a large number of crash

recorders in vehicles which are also measured with a CDC could

lead to either (1) a calibrated CDC, (2) a redefined CDC which is

more useful in the context of defining crash dynamics, or (3) both.

The CDC has the advantage that it can be applied to any

accident vehicle after the crash without benefit of additional

-81-
instrumentation, and thereby reducing the problem of sample

selection. It has the disadvantage, at present, that its

capabilities for providing a measure of crash dynamics are not

well known, and that these capabilities must depend on better

knowledge of vehicle structure than is generally available in

the literature.

The SMAC Programs

The MAC development is intended to provide computer assistance

to the reconstruction of a traffic’ accident. The method involves

inputting certain observational and factual data into the computer,

and iterating a solution which best fits the final rest positions

of the vehicles involved. The iterative computer programs can

be run from data acquired with a special observational tool (the

SMAC van) or can be run with data taken by manual methods. In

the latter instance, in particular, the technique should be applicable to a large number of collision analyses.

The present SMAC programs are limited to the ground plane,

and, as a result, are not able to handle certain odd collision

configurations-- such as rollovers, or vehicles running down an

embankment. To the best of my knowledge the SMAC program output

has hot been compared directly with crash recordings, although

from some of the remakers at the recent conference I would assume

that NHTSA has either started to make such comparisons or has

done some. Crash recordings have been used to compute A V. This

output of the SMAC programs has been validated to some extent.

In addition to the ground plane limitation, these programs

are also limited by the accuracy of input data on the structural

characteristics of the vehicle. However, the capability exists

for removing these deficiencies. The problem of this point seems

to be one of choosing the optimum tradeoff of input data requirements and modeling sophistication versus the detail and accuracy

of the resulting output.

-82 -
ments on accident involved vehicles with results of instrumented

crash tests (as described by Campbell in SAE paper 740565) or

by Patrick (in an analysis of Volvo crashes). In addition, the

TAD scale as applied by several police agencies is a crude measure

of crash severity with the potential for relatively Universal

employment. Each of these will be discussed briefly below.

The CDC (or VDI)

The CDC was developed as a means of recording crash damage

in a simple codable form. It consists of 6 elements--the clock

direction of impact, four letter codes indicating the location of

the damage (vertically and horizontally) and the general nature

of the object struck, and a numeric code (1 through 7) indicating

the extent of deformation. An experiment conducted by Cromack

at Southwest Research Institute, and reported in an SAE paper,

indicates that the CDC as presently defined can, in general, be

assigned consistently by a trained investigator. The CDC, however,

is not directly convertible into a measure of the crash dynamics

because it depends in part on the structural characteristics of

the particular car under investigation. Further, it was not

developed primarily as a substitute for a measurement of the

deceleration characteristics of the crashed vehicle, but rather

as a simple codable record of crash damage.

The data elements contained in the CDC, however, when related

to a knowledge of the vehicle structure (and perhaps other information about the crash circumstances) could permit a computation

of some of the crash dynamics. An experiment could be conducted

(largely with existing data) to define the ability of the CDC

to predict much of the output desired from crash recorders. If

an initial experiment looks promising) a large number of crash

, recorders in vehicles which are also measured with a CDC could

lead to either (1) a calibrated CDC, (2) a redefined CDC which is

more useful in the context of defining crash dynamics, or (3) both.

The CDC has the advantage that it can be applied to any

accident vehicle after the crash without benefit of additional

-81-
instrumentation, and thereby reducing the problem of sample

selection. It has the disadvantage, at present, that its

capabilities for providing a measure of crash dynamics are not

well known, and that these capabilities must depend on better

knowledge of vehicle structure than is generally available in

the literature.

The SMAC Programs

The SMAC development is intended to provide computer assistance

to the reconstruction of a traffic’ accident. The method involves

inputting certain observational and factual data into the computer,

and iterating a solution which best fits the final rest positions

of the vehicles involved. The iterative computer programs can

be run from data acquired with a special observational tool (the

SMAC van) or can be run with data taken by manual methods. In

the latter instance, in particular, the technique should be applicable to a large number of collision analyses.

The present SMAC programs are limited to the ground plane,

and, as a result, are not able to handle certain odd collision

configurations-- such as rollovers, or vehicles running down an

embankment. To the best of my knowledge the SMAC program output

has not been compared directly with crash recordings, although

from some of the remakers at the recent conference I would assume

that NHTSA has either started to make such comparisons or has

done some. Crash recordings have been used to compute A V. This

output of the SMAC programs has been validated to some extent.

In addition to the ground plane limitation, these programs

are also limited by the accuracy of input data on the structural

characteristics of the vehicle. However, the capability exists

for removing these deficiencies. The problem of this point seems

. to be one of choosing the optimum tradeoff of input data requirements and modeling sophistication versus the detail and accuracy

of the resulting output.

-82 -
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-86-,
APPENDIX H

ADEQUACY AND LIMITATIONS OF CURRENT DATA SYSTEMS

Marie D. Eldridge

NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION

January 16, 1975

-87-
ADEQUACY AND LIMITATIONS OF CURRENT DATA SYSTEM

Remarks By

Marie D. Eldridge, Director

Office of Statistics and Analysis

National Highway Traffic Safety Administration

AUTOMOBILE COLLISION DATA WORKSHOP CONFERENCE

January 16, 1975 -Rosslyn, Virginia

In the very short time available to me this morning, I’m going to try

to give YOU some highlights about the capabilities and limitations of our

.

current data systems. I will also try to indicate where we see improvements

within the near future.

However, before talking about the capabilities or the limitations, we

really need to ask “capabilities or limitations for what?” So let’s briefly

talk about the objectives of our accident data systems.

First, we have to classify and count accidents. We need to determine the

frequencies of accidents and classify them by their causal mechanisms, by their

injury-producing potentials.

Second, we need adequate measurements of accident consequences, injuries,

property damage or broader measures such as societal costs, a much

neglected area and subject to

utlimately our decisions have

Third, we need to be able

that is, to relate the causal

great controversy but still one on which

to rest.

to describe, or model, crash injury mechanisms,

mechanisms and injury-producing potential to

the actual occurrence of crash in-jury. This is particularly important in

predicting the effects of proposed safety countermeasures. We have to

-88 -
describe functional relationships between numerous factors which at present

are considered separately. All of these things that I have mentioned enter

into the process of determining the efficacy and the benefits of existing

or proposed safety measures.

Let US consider the criteria by which we should assess our crash data

collection systems. It is my view that a comprehensive approach and a

comprehensive consideration of all the data requirements that combine to give

us the needed information is essential. It just won’t do to get vey high

accuracy in estimating speeds if at the same time the sample of accidents for

which we obtain this information cannot he used to generalize and cannot provid e

US with the proper support for a rule that will apply to the whole country.

High accuracy in one part of the data system can easily be nullified by

weakness in another and, to quote an old saying there iS no need to put

a micrometer on the end of the yard stick.

View Graph II

I have listed in this view graph some of th e

in assessing crash data systems. There are many

may help provid e a framework for discussing our

criteria that we may use

ways of doing this but this

present systems.

First of all, there is the quality of the data. We are concerned with

its representativeness and in our ability to generalize from it to a national

crash population. A sample that contains only new cars or only auto fleets

is not representative. Frequently, we may have a situation in which sample

populations as defined are representative, but in fact, because of missing

data or non-returns, we don’t get an unbiased sample.

-89-

,.
A second criterion is accuracy of information. One of the reasons we

are here today is the inaccuracy of certain information that we are now

getting in crashes, namely the various speed parameters.

A third criterion is the ability of the system to be responsive and ..—

timely. The data need to be collected and processed quickly enough that the

information is available before the decision has to be made. The sample sizes

have to be large enough that we can have confidence in the decisions based on

the results. At the same time we have to concern ourselves with costs arid

make tradeoffs between costs and precision. Next there is the breadth or

extensiveness of coverage of the information provided by the system in the many

parts of our highway safety information matrix. And last but not least the

cost efficiency.

View Graph III

If we had a great deal of time we could consider all this at the data

item level or individual field level, but even to cover this matrix in any

detail

I will

of the

will have to be left for possible discussion later in the conference.

simply mention that under exposure items we have the characteristics

vehicle occupants and the amounts of driving by various driver types,

their characteristics, licensing, training and so on. We have under vehicle

exposure the counts of vehicles by type, travel amounts, their conditions,

size, etc. The

-90-
IV.

environmental exposure includes such things as traffic density, speed

limits, highway types, design and so on. We could go down this matrix

cell by cell and fill in the types of things that need to be considered.

The final and very difficult quality has to do with the cost-efficiency

of the data systems. When a decision involves a high cost or an extreme

inconvenience, a great deal of effort will generally have to go into

the data collection and analysis. However, we also wish to keep our data

collection efficient in the sense of not collecting information for which

there is no need or employing personnel or

accurate than is really necessary.

Now let us turn to the capabilities of

equipment more skilled or more

some of our current data

collection systems. Basically, we have two types of systems. The first

is based primarily on the state or local traffic and related records

systems. The second type involves special investigative work. The state

records are kept primarily for purposes other than safety analysis.

However, we utilize their records for the Fatal Accident Reporting System,

which is essentially a census or 100 percent sample of fatal motor vehicle

accidents and for the planned National Accident Reporting System, which

will be a probability sample of all accidents, of a given threshold.

The accuracy of the information provided through the State traffic record

systems varies of course. In some areas of particular interest to us

it is quite poor. Speed causal factors and restraint systems usage, for

example, may be misreported or unreported frequently. Timeliness is

generally not a problem. It usually takes only a few months before an

accident is in the file and therefore accessible to us. As far as the

-91-
quantity of information is conerned, the State Traffic Record Systems are

likely to provide us with a large number of cases for the more frequent

types of accidents and the items of highest interest, but it is surprising

how often in other circumstances we run out of data. The most obvious

example is in making comparisons between makes and models of cars. When

we get to some types of vehicles that are not on the road in large numbers,

we have a very hard time collecting enough accidents to have a useful

sample. The breadth of the information provided is generally not

adequate. Impact speed for example is reported only in one State; traveling

speed in about half the States and not for all accidents even in those

States. Restraint system usage is not reported in most

States and in many where it is reported, it is not reported for uninjured

occupants. In-jury information and causal factors are sketchy. Post crash

information, societal cost and property damage are usually not in the file.

It has been generally recognized that we can not obtain adequate

information to support the standards by relying solely on these basic

records oriented data systems. The second type of accident data collection

system - those in which specific data collection efforts are sponsored or

paid for by either the Federal Government or some other interested organization

in the safety field such as MVMA or the Insurance Institute for Highway

Safety. In these systems the investigation is likely to be carried out

wholly or in part by professional accident investigators, resulting in

substantially more extensive information. NHTSA has under way three types

of sponsored studies.

-92-
First is the Multidisciplinary Accident Investigation teams. These

teams do both on-scene and off-scene in-depth investigations. Teams have been

performing clinical in-depth studies of selected accidents in the U.S.,

primarily on new cars, since 1969. The representativeness of the sample

that has been produced up to this time is poor. Different teams have been

covering accidents most relevant to their special interest. That situation

is gradually changing. The accuracy is generally good. Nevertheless, there

is considerable room for improvement. We have no capability for getting a

time history of the crash forces and accompanying accelerations except

through computer simulation such as the SMAC program. At present we have

about 6,000 MDAI cases in the file. Many of these were not the result of

on-scene investigation. There is detail on most aspects of the accident with

the exception of exposure. As a system for producing statistical information

needed for supporting our safety standards, the on-scene in-depth investigations

cannot be regarded as cost effective. The average cost per case is about

$2,000. The cost decreases to about $800 per in-depth case if the on-scene

investigation requirement is Eliminated. This does reduce the accuracy of

reconstruction of the accident and of course affects the estimate of speed.

At a somewhat lower level of detail NHTSA has developed a system in

conjunction with MVNA to collect a probability sample of towaway involvements

of new cars in five selected regions of the country primarily for the purpose

of evaluating active and passive restraint systems.

-93-
assembled from the police report, a doctor’s

vehicle investigation, and driver interviews

Data items collected are restricted to those

of restraint systems effectiveness. This is

Data ar e

report, photographs, a brief

performed by field technicians.

for the

needed/statistical analysis

an example of what we may

term a Level II study. We expect to make national estimates based on

post stratification. The accuracy of the information in the selected

data items’ should be good, nearly as good as what comes from the multidisciplinary in-depth investigations. The quantity will be adequate to

match the needs for estimating safety belt effectiveness. Because of the

small numbers it is not likely to give us what we need for estimating air

cushion effectiveness, very soon. As far as the breadth of the file is

concerned, it is designed for calculation of crash injury rates and

evaluation of restraint systems effectiveness. It does not address

exposure or accident causation. Speeds and occupant contact points are

not determined. The cost is around $100 per case.

A third type of sponsored system is basically a bilevel investigation

or one in which there is a supplementary investigation carried out by

police with NHTSA or other funds added to take care of added costs. We

have under development a system for sampling pedestrian and bicyclist

accidents

in several hundred localities. The

system is designed to answer questions at the level of detail that we

-94-
nced to determine gross behavior and provide some good input for countermeasures. The data to be collected is primarily concerned with the nature

and location of pedestrian and cyclist accidents as well as certain other

items affecting visibility which would not normally be collected in the

state accident reporting system. The cost per case is expected to be high

primarily because of the relative rarity of pedestrian and bicyclist accidents

and because in order to get an adequate probability sample that will properly

represent rural areas, it is necessary to include localities with a very

low frequency of accidents. The set-up time in preparing to get the

supplemental investigations done in small localities is the same as it is

in large localities, but the data rate is low and the total cost is

increased disproportionately.

AS We look ahead to potential improvement in the capabilities of our

v.

current systems that may be in sight we are really moving in two directions.

The first is to create a national accident sampling system based on a

probability sample. We have a contract under way with the Highway Safety

Research Institute at Ann Arbor to help develop this system that will

include some of the current investigative efforts but provide for sufficient.

control of the selection of accidents that we will get a sample from which

we can generalize to national crash populations.

The second area in which we anticipate improvements is in determining

crash dynamics. These efforts, are of courses of paramount importance to

this workshop. The work with the crash recorder is being covered by my

colleague, Lynn Bradford. The other approach, SMAC, the computer simulation

of the accident dynamics will be dealt with by our representatives from

Calspan but I would like to say a few words about our experience with it.

-95-
This program uses vehicle rest positions and impact damage to calculate

impact velocities, the velocity change during the crash, acceleration pulse

and predicted damage. The goal is to reconstruct the accident crash

dynamics in sufficient detail that inputs needed by our standards makers

are available. The use of the SMAC program may permit us to get, at a

reasonable cost, an adequate representative sample of crashes once our

national accident sampling program is up and running. However, it should

be pointed out that the crash recorder is clearly a very valuable tool in

developing necessary refinements to the SMAC program. Ideally, and this is

IF

a moderate size "if",/the crash recorder and the SMAC work hand in hand well

enough, we can succeed in reducing considerably the numbers of crash recorders

required down stream. Precise calibration of the SMAC program will enable

us to use Level 2 data for crash dynamics at a reasonable cost. Currently

the cost per case, using the SMAC program is $150.

In the short time available to me I have had to gloss over lightly

much of the work related to

to provide detailed back-up

these points. They are Don

Before finishing these very

crash data. Three members of my staff are here

and to join in any subsequent discussion of

Mela, Dr. Charles Kahane and Dr. Charles Moffatt.

brief remarks, I want to repeat a point I made

earlier. We need to consider all relevant aspects of the data systems in

a comprehensive fashion before making decisions on any of them separately.

While we may not be able to devote that amount of detail to all aspects of

the data systems in this conference I think that at least the major aspects

should be considered before coming to any conclusions or decisions.

-96-
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APPENDIX I

A DISCUSSION OF DATA GATHERING SYSTEMS

Edwin A. Kidd

CALSPAN CORPORATION

January 16 & 17, 1975

-101-
INTRODUCTION

A data sampling plan that provides an accident data file that is

representative of the national population is important. A system for data

processing, storage and retrieval to allow early determination of trends in

accident, injury and fatality frequencies is essential. But the most critical

problems are those concerned with the collection of consistent, coherent data

on individual accident sequences with a volume far exceeding that now

available.

For too long, those concerned with accident studies of the effects

of safety standards already in force have had to make do with either too small

samples of reasonably good data or relatively large samples of data whose

content is inadequate for the purpose. In the first category is the data bank

(and “bank” is too grandiose a term) that has resulted from the individual

federal teams of multidisciplinary, professional investigators. These teams

can serve useful purposes in special studies, in discovery of problems that

would otherwise go undetected and, particularly, in the area of accident

causation. By their very nature, they cannot provide a sufficiently large

data sample relevant to the implementation of standards aimed at injury and

fatality reduction without excessive expenditure of funds.

In the second category are the presently available state data banks

of relatively low content data obtained through the use of routine police and

driver reporting. These data have been valuable in demographic studies, in

the broad-look definition of trends and in statements concerning the magnitude

of the overall problem, primarily in fatality frequency. In most cases, such

data is totally inadequate in content and precision and, despite the relatively

large numbers available at relatively low cost, cannot adequately define injury

and fatality reduction resulting from standards implementation.

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There is a third category of data collection systems that has

evolved over the past few years that lies between the very detailed team

approach and the routine police reporting as established independently by

the states. The potential exists with this multi-level approach at selected

centers around the country (present examples include Calspan in New York,

HSRI in Michigan, and HSRC in North Carolina) for a combined data bank that

would be a major step toward the attainment of a greatly increased sample

size with, and most important, accurate individual accident data with the

content required for the purpose.

proper utilization of the potential of these data centers can be

realized only if investigator and accident reconstruction aids are implemented

that will allow the police to obtain the necessary information with orders of

magnitude improvement in accuracy. Local and state police already have the

charter to investigate accidents. There are no unsurmountable problems in

providing them with the new tools that have been developed for collecting the

data that would be the basis for a national data bank sufficient for NHTSA

needs in surveillance and effectiveness studies.

The list of specific data elements in each accident that are

deemed to be essential can hardly ever be complete for the serious analyst.

However, the routine and continuous collection of accident data can be tedious,

time consuming and costly. Every effort must be made to keep the data requirements to a sufficient set commensurate with the need.

Such sets have been defined a number of times for various ongoing

studies. The one presented in Figure 1 is stated in somewhat general terms

as it is required, in this instance, primarily for the comparison of data

gathering techniques.

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DESCRIPTION OF INDICATION OF DETAIL

GENERAL ACCIDENT INFORMATION

SPECIFIC VEHICLE INFORMATION

OCCUPANT INFORMATION

DRIVER INFORMATION

IMPACT ENVIRONMENT

SINGLE OR MULTIVEHICLE, RURAL OR URBAN,

HIGHWAY CATEGORY, PROPERTY DAMAGE ONLY OR

INJURY, OBJECT STRUCK, OVERALL SCENE

DESCRIPTION, ROAD SURFACE, AMBIENT CONDITIONS

MAKE, MODEL, VIN, IMPACT DIRECTION AND

DEFORMATION (VDI OR IMPROVED EQUIVALENT),

AVAILABLE RESTRAINT SYSTEM, LOADED WEIGHT,

TIRES, INOPERATIVE SYSTEMS PRIOR AND AFTER

IMPACT

SEX, AGE, HEIGHT AND WEIGHT, INJURY (MEDICAL

REPORT), SEATED LOCATION, USE OF RESTRAINT

SYSTEM

DETAILS AS IN OCCUPANT ABOVE PLUS DRIVING

EXPERIENCE, TRAINING, CONVICTIONS, PHYSIOLOGICAL

CONDITION, PSYCHOLOGICAL INDICATIONS, ACTIONS

PRIOR TO AND DURING ACCIDENT SEQUENCE

SPEED AT IMPACT, RESULTANT SPEED CHANGE

TIME HISTORY, COMPARTMENT DECELERATION

Figure 1 ACCIDENT DATA REQUIREMENTS
Even this rather simplified listing appears formidable. However, to some degree each of these elements or approximations thereof are

being obtained, by one means or another, by some of the present ongoing

programs. There is no element in the outline presented in Figure 1 that is

not germane to existing standards. If we settle for a system that provides

accurate information less than this and/or only for a quantity of a few

hundred or even a few thousand cases, NHTSA cannot do the job it has been

directed to do.

Definition of the total number of accident cases required annually

for an adequate national data bank can be made if (1) the questions to be

asked of the system can be identified both for the present and future; (2) the

accuracy with which the particular data elements can be measured is known or

can be appropriately approximated; and (3) the statistical analysis techniques

to be employed can be agreed upon. This is not meant to imply that such

analyses and decisions should not be made. However, there are no statistical

procedures that can adequately overcome the past and current inaccuracies with

which such extremely important data elements as impact speed and speed change

have been reported if they have been reported at all.

.—. — —..

There will need to be a parallel effort of statistical analyses to

indicate what questions can be addressed with acceptable statistical significance

as a function of particular sample sizes along with the determination of the

funds that can be made available. The financial impact of standards on

the consumer has been and will be considerable — billions of dollars annually.

Figure 2 presents an average cost per car for the FMVSS to date based upon

idividual autombile manufacturer’s data. It seems prudent to schedule

funding for the primary surveillance effort -- accident data collection --

commensurate with the far reaching decisions that depend upon such data.

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— —

400

300

200

100

0

----- CUMULATIV E

\NNUAL

/

1966 1967 1966 1969 1970 1971 1972 1973 1974

YEAR

Figure 2 AVERAGE COST IMPACT OF FMVSS ON AUTOMOBILE PRICE

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Data Gathering Techniques

In order to obtain the data required on each accident, every

accident analyst would gladly utilize whatever data gathering techniques are

available. Ideally, crash recorder information, police and driver reports,

intensive investigation team reports and on-scene reconstructions of the

accident through computer aids to investigators would all be gratefully

accepted by every serious analyst for each accident. In fact, no analyst

would refuse any available high speed photographic coverage (in color, of

course) .

Obviously, it is neither practical nor essential that all of these

systems be provided for the achievement of the basic national data bank. It

has already been stated that the intensive investigation teams may have other

purposes but cannot provide the data in the quantity required. It has also

been noted that existing state data, comprised of merged police report, vehicle

registration, and driver licensing files do not provide the content required

for the evaluation of safety standards.

Crash Recorders

Crash recorders can only provide a portion of the desired

information as a supplement to continuous accident investigations. At best,

a recorder can provide only the information outlined in Figure 1 under “Impact

Environment” plus driver control actions during the accident sequence and an

identification of the vehicle in which it is installed. Despite the fact that

the information a crash recorder is designed to obtain is the impact environment, and that this is the data now totally lacking or sadly inaccurate, a

detailed accident investigation would still be required to provide the essential

general accident, specific vehicle (including the other vehicle) and occupant

and driver information. Thus, the overall cost of an accident investigation

would include essentially the present costs plus those associated with the

provision of crash recorders.

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The numbers game must be considered as well in the consideration of

crash recorder Installations. The actual number of accidents that would be

available for analysis would be a marked attenuation from the total number of

crash recorder installations (Figure 3). Assume that recorders were installe d

in 100,000 automobiles. No more than 1 in 4 of these automobiles would be

involved in any sort of accident annually. This reduces the number of accident

cases with crash recorder information to no more than 25,000. If it is further

assumed that the accidents of principal interest are those of more than minor

severity, for example, tow-away accidents (approximately 12.5% of all accidents),

then only 3125 accidents would be available. If we examined only the highest

volume model of the major American manufacturer (approximately 25%) the number

of accidents available would be approximately 781. Further division of these

accidents into accident type, direction of impact, etc., would further

diminish the numbers. This severe attenuation would be greatly increased for

car make and models other than the one with the greatest penetration of the

market.

It is recognized that the crash recorder is designed to provide

crucially important information on impact environment that has not been

otherwise available, at least in quantities with acceptable accuracy, However,

there is now available another method, as discussed below, for obtaining this

information with accuracies that appear excellent. Both methods should be

compared in staged crash tests and considered for some possible joint use as

mutually reinforcing data sources. However, the computer aided system, with

its outputs of a detailed scene description and an accurate reconstruction of

the accident, offers the most promise, as a fundamental element of a continuing

data gathering system.

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ANNUAL CRASH RECORDER INSTALLATIONS 100%

VEHICLES INVOLVED IN ANY ACCIDENT 25%

VEHICLES INVOLVED IN SEVERITIES > TOW AWAY 3.125%

MAJOR MANUFACTURERS HIGHEST VOLUME MODEL .078%

Figure 3 CRASH RECORDER EQUIPPED AUTOMOBILES

IN ACCIDENTS
— .—

Computer Aided Investigation and Reconstruction ———

With support from NHTSA, this on-scene accident investigation and

reconstruction system has been developed and demonstrated (Figure 4), An

automated range-finder transit with associated computer hardware and readout

(Figure 5) provides a drawing of the accident scene and supplemental accident

information as required (Figure 6). These physical evidence data are

transmitted via a radio-telephone link to a centrally located computer which

returns a reconstruction of the accident (Figure 7).

In actual reconstructions of staged accidents, this investigators

tool has faithfully reproduced the accident sequence with impact speed and

speed change reconstructions of 2-3% accuracy. With this system, police

investigation teams can generate high quality accident data in the course of

performing their normal police functions. Yet the system has been found, during

field trials by police personnel, to actually ease the tasks of scene measurement and reporting. Thus, both the users of accident data and the police can

benefit from adoption of this system.

The economics of adopting the system would be extremely attractive

from the viewpoint of elimination of labor costs in the generation and reporting of accident data for research purposes. The end product is already in

digital format for statistical analysis.

The nature of the output from the van also lends itself directly to

a central data bank or regional data banks receiving reconstructed accidents

and supplementary data over existing telephone lines. This continuous updating

of current data is particularly attractive. At present, the best a state can

do, those few that can supply merged accident tapes, is provide a year’s data

six-eight months after year’s end. A dedicated data collection center, such

as presently sponsored by NHTSA, can provide computer tape updates of collected,

augmented police reported data every three months with a three month delay.

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-111-
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A A

x

FIGURE 6 SCENE AND ACCIDENT RECONSTRUCTION

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GRAPHIC DISPLAY OF OUTPUTS OFACCIDENT RECONSTRUCTION

I

I

I

I x

I

I

I

I

I

\

\

COLLISION AND TRAJECTORY

— ————

\ —— — ——

.

—

L Y

f

.— —

/

i

I

I

I

I

I

I

I

I

—— —

\

t

I

I

I

I

I

I

AXIS INTERVALS ARE 10. FEET

I VEHICLE I

RECONSRUCTED POSITIONS AND VELOCITIES AT IMPACT DISPLAYED FINAL POSITIONS

1.9 6.0

10.0

FIGURE 7 SAMPLE ACCIDENT RECONSTRUCTION

-114-
—

Data Collection System

The mobile accident van will

after some additional field trials. The

model (SMAC), as incorporated in the van

hardware, has been distributed and is in

be ready for general police use

accident reconstruction computer

reconstruction software and

extensive use; additional validation

for a variety of accident situations is planned. The total system works and

works very well. It is appropriate to consider how it might be incorporated

in a complete data collection system that would provide greatly improved and

accurate accident data with the quantity and content required for surveillance

of standard’s effects on accident consequences.

strategically located data centers have been suggested for the

collection of regional data samples of the multilevel type. An appropriate

distribution of accident vans for use by police investigators within each of

these regions would provide continuous data into regional data banks and/or

to a single data bank.

There are two primary options

investigators can be equipped with either

The Scene Van would provide a description

for van configurations. Police

a Scene Van or a Reconstruction Van.

of the physical evidence an d

supplementary accident data (Figure 6). Hard copies of this information in

appropriate format would be available as the police report. In addition, all

data would go on tape cassettes to be forwarded to the particular data center

for reconstruction of the accident by the SMAC model. The reconstructed

accident information would supply the center’s data bank . Appropriat e

retrieval and analysis programs would provide immediate analyses as required.

b

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.

Reconstruction Vans, with either self-contained reconstruction

capability (more comprehensive on-board computing equipment) or radio link to

a regional time-share computer or computers would by-pass the step of accident

reconstructions at the data center. Also, a more desirable feedback to the

accident investigator at the scene would be available. (A successfully reconstructed accident is the best check of the completeness and accuracy of the

scene data.) Each reconstructed accident data set would be stored (short

term) within the van and transmitted, when convenient, to the data center at

available terminal locations (already present at police agencies).

A rough approximation of the cost for two assumed data collection

systems is given in Figure 8. These are given to provide an approximate

range of system costs for collection of 100,000 cases annually. The cost of a

radio link reconstruction van system would be somewhat less than the selfcontained van with a resulting overall cost close to that of the scene van

system. Final selection among these alternatives should consider, in addition

to basic costs, operational factors including the advantages of program

updating and modifications with either the Scene Van or the radio-link

Reconstruction Van and the overall data improvement that would result from

the Reconstruction Van.

Regardless of the system selected, costs per case of less than

$100 are estimated. This appears to be quite a bargain. The system would

provide 100,000 cases per year for whatever investigation criteria is

desired, e.g., tow away cases. Costs per case are essentially independent

of data sample size. The assumed rate of cases per van per year is

conservative, considering that police agencies operate 24 hours per day.

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I

a

15K

-117-
.

Obviously missing from the estimates of Figure 8 are labor costs

for data acquisition at the scene. It is assumed that police would do the

investigations. With police use of vans for their own investigative purposes

with improved efficiencies over the present, acceptance of the vans should

be readily realized.

Based upon our experience to date, we believe the usefulness of

this mobile system to the police themselves can be demonstrated and there is

no concern that they cannot properly operate the equipment. Implementation

of a total collection system employing this scene data gathering capability

will provide NHTSA with the information needed.

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APPENDIX J

MASS ACCIDENT DATA ACQUISITION

AND WHY IT’S NEEDED

John Versace

FORD MOTOR COMPANY

January 16, 1975

-119-
MASS ACCIDENT DATA ACQUISITION AND WHY IT’S NEEDED

OTA Automobile Collision Data Workshop

John Versace

Ford Motor Company

January 16, 1975*

Accident data have been collected for a long time, and we have learned

a great deal from them. These data aid in establishing safety need and proper

priority of effort. Government, industry, and the public can benefit from

more knowledge regarding the real world of traffic. However, times change and

designs change, and we believe the present rate of gathering accident information on current designs and events is not adequate. Large amounts of data,

carefully collected so as to assure representativeness, are needed. In addition, special kinds of data, more accurate than numerous, perhaps, are also

needed to fill in some significant research lacks.

Approaches to Data Collection

There are three basic approaches to data programs, with some variations. First, the researcher might incisively phrase the particular questions

that are going to be asked of the data, and he would design a data collection

program to answer those questions. A point of particular significance in this

approach is that the data collection program is then part of an integrated

research project. For example, both the MVMA and NHTSA have, during the past

year, been conducting a study to measure the accident performance of the 1974

interlock type of restraint in comparison to the 1973 system. The number of

items of data collected in each case were deliberately kept few so that investigative resources could be allocated toward getting as many cases as possible --

instead of much data on fewer cases.

*With additions, January 22, 1975.

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The second type of approach would be to run the study like a controlled experiment, in which the hardware to be evaluated would be assigned

to members of the public in such a way that there would be both broad representativeness of use and freedom from bias, those not receiving the device

being the control group. This approach is seldom practical, although manufacturers sometimes are able to equip certain cars with experimental features

prior to their full market introduction in order to develop field experience

with them. Again, the data collection is integrated into the research project.

The third approach to data collection -- and the one I believe we are

concerned with here -- is to create a data file which is a microcosm, in all

its particulars, of the real world. This approach is independent of any particular research project; its purpose is for the data file to “become” the real

world insofar as any researcher is concerned. Different researchers will dip

into that data file to answer questions which may arise as issues emerge,

issues perhaps unforeseen by those who devised the data collection scheme. Such

a method requires highly detailed recording of data on an enormous number of

variables. This allows for variables previously disregarded to now be investigated, and also allows the researcher to control confounding effects by selecting

for comparison only those cases in which the effect of the extraneous variables

cancels out. The most desirable kind of data collection approach, providing

sufficient resources can be brought to it, is this third type. If resources

are not sufficient, then probably the first type of approach -- in which the

data program is tailored for the specific questions to be asked of it -- would

be most appropriate.

Uses for Data

Among the uses for accident data -- and each use has its own requirement on scope and precision -- are: (i) evaluating the safety performance of

-121 -

.
—.

past and current safety designs, and most importantly, verifying that required

countermeasures have, in fact, been effective; (ii) determining if particular

safety problems are of such magnitude that countermeasures are needed and supporting the specifics of rulemaking; and (iii) supplying normative information

about accident occurrence so the future effect of countermeasures not yet

designed or produced can be anticipated and a wise policy regarding them be

instituted.

In regard to this last point -- anticipating future performance --

let’s consider an example. It is easy to conclude that if the 30-mph crash

test requirement contributes to reducing death and injury, then surely an

increase to 40, 50, perhaps even 60 mph would be proportionately better. But

there is very little information available that would unequivocally support

such a conclusion. Because there obviously are no cars on the road meeting

such advanced requirements, we cannot test this conclusion by comparing their

casualty rate to cars meeting only the 30 mph criterion -- assuming we had

accident data collection and analysis procedures adequate to the task. Because there are no such cars, resort must be made to calculation.

Two things are needed to make such calculations: real inputs of

population exposure -- drawn from accident data -- and theoretical system

models. Validity of the models will of course be an important matter to

consider.

Need for Population Exposure Data

Being able to determine whether, or in what way, to increase the test

requirements of crash performance standards, or to inaugurate any rule, depend s

upon our being able to predict the probable effect of such actions in the

future. particularly lacking as an input to any calculation of future effects,

is an accurate estimate of the dynamic environment to which people are exposed.

)

f 4

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The particular form of the exposure variable most useful for calculating the

magnitude of need and in estimating the future effects is the probability

distribution of collision speed (with all types of likely obstacles.)

Ordinary accident investigation data can be useful in estimating

crash speeds, given some care in adjusting for the mechanical nature of the

struck object. However, derived speed estimates from accident reports quickly

lose reliability as impacts other than head-on are considered. The ogival

cumulative distribution of barrier-equivalent speed has been a prominent

part of most analyses aimed at estimating population exposure and hence need,

and in calculating the probable effectiveness of different restraints. A single

shape and location of this curve has not been accepted among all its users.

The absence of this

should be a factual

belief that a crash

one item of information on occupant exposure can make what

matter rather a matter of contentious advocacy. It is our

recorder supplement to a general accident data program has

the potential to assist in clarifying this particular area of need.

Accuracy of Crash Severity Data

For a successful program of crash severity determination, there must

also be the right protocol for defining an accident so that the resulting distribution of measurements

“interesting” cases -- an

able today. If the speed

inflated due to errors of

speed crashes than really

is not biased upwards by deliberately selecting only

unfortunate characteristic of most data sets availdistribution is incorrectly displaced upscale, or

measurement, there will appear to be many more high

occur; the result will be to lean toward excessively

high crash requirements, with resulting cost-effectiveness being less than it

appears. While precision of measurement of crash speed iS important in estimating the speed distribution, it is even more important that there be no bias in

the data collected.

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It may be useful here to distinguish between the accuracy of

measurement and the accuracy of estimation, in the statistical sense. The

former refers to the degree of correctness in any one reading, and the average

measurement error is an index of this quality. Accuracy of estimation, for

data analysis purposes, refers to the relative absence of bias in the sample

of data: i.e., that the sample values fairly reflect the population from

which they were drawn: that the sample distribution can be accepted as an

estimate of the population distribution because there are no funnies in it

which warp it, or skew it, or displace it except for the action of random

influences.

Different data purposes place different requirements on measurement accuracy. Crash recorder data presumably are more accurate than other

indices of collision severity, such as the measured vehicle deformation or

the Vehicle Damage Index (VDI). Whether such accuracy is required depends

on the type of study. For many purposes, plan view photographs of the case

and struck vehicle would be a significant improvement over VDI, as they would

allow for an energy-derived calculation of severity.

When comparing injury outcome between accident cases with, as compared to without, a side guard beam, for example, we would want to control

for collision severity because the degree of injury is correlated with collision severity. The control could be effected either mathematically or by

partitioning the sample of cases in groups of equal collision severity. Controlling on collision severity will do two things: increase the efficiency

of the comparison and eliminate the bias that results from fortuitous concentration of milder collision cases among one or another

comparison.

Because the degree of injury depends on many

impact severity --such as restraint use, occupant age,

of the groups under

factors other than

and adventitious

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posture -- the correlation of injury with the collision severity control

variable is necessarily going to be less than perfect. As a result, increases

in the precision of measurement of collision severity will not proportionally

improve the efficiency of making the comparison when using it as a control

variable. So, it is not so important to have high precision when doing

routine accident comparison studies. The crash recorder has a different

utility, and its evaluation should be based on other considerations.

Crash Recorder Use

A crash recorder will have utility for at least three types of studies.

The first, as already mentioned above, is to provide correct normative information about such things as -- and particularly for correctly establishing -- the

occupant exposure in terms of the probability distribution of collision speeds.

To make such a determination requires a research project to be defined with 

this as its objective; the project could be based on the crash recorder as a

particular tool of unusual usefulness. The research project could terminate

when the determination has been made. Since the accuracy provided by the crash

recorder is not essential for the kind of data-adjusting purposes described in

the paragraph above -- i.e., in order to provide a control variable for accident case comparisons -- it would not be needed as a permanent part of a

national data collection program. It should be viewed primarily as a research

tool used for fairly particular purposes in a particular research program, more

than an instrument for general accident investigation.

Another use for the crash recorder would be in research programs for

establishing human tolerance to impact and to aid in establishing dynamic

specifications for impact test devices. Thus, crash recorder data could be

used as inputs in the programming of experimental crash tests or computersimulated tests. These studies would determine the design characteristics

needed in the test devices (e.g., crash dummies) so they would yield test

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readings comparable to those experienced by actual

kind of research requires data that are in dynamic

rating scale indexes or qualitative descriptions.

accident victims. This

physical form -- not

This usage of crash recorders would be contained within a research program designed to that end,

and except for considerations of administrative efficiency, not be an

intrinsic part of the national accident data collection system.

Still another useful purpose for the crash recorder would be to

calibrate or to improve the more subjectively determined indexes which are

now commonly used in accident investigation. Again, once that calibration has

been effected, there would be no on-going necessity for the crash recorder.

Other Data Needs

There are two other areas of safety evaluation to which there has

been inadequate attention. The first is to measure the overlapping and interactive effect of different safety requirements: e.g., strength of door fixtures

and occupant restraints. Some safety evaluations, carried out in different

studies, can count the same persons as being saved more than once by different

means in each study, so that the total of the saved casualties might even exceed the population at risk. Our own studies have had this problem.

But even more significant is the almost total lack of information

regarding the safety benefit in the 100-series federal standards. The whole

concept of accident causation and avoidance needs to be clarified: to date it

has been expressed more figuratively than in quantitative terms which will

relate to vehicle design. Lack of good ideas in this area suggests that a

conceptual breakthrough must be made before we are able to properly attribute

that part of causation/reduction to the vehicle and its design, separate

from the mediating influence of the driver and of the roadway, and so cost-

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--—. — .-

effective countermeasures can be imposed at the right place in the system for

each aspect of accident causation, and in such a way -- and this is crucial --

that the specific effect can be evaluated, both prospectively and retrospectively, in accident data.

Procedures for establishing the safety effectiveness of both the

current and proposed 100-series standards should be a major research challenge

to the government and industry in the years to come. Current government accident avoidance research emphasis is to experimentally compare different vehicles

on arbitrary control tasks. But programs of a different type are also needed,

programs that will define measures of accident avoidance performance and then

from that establish minimum criterion levels for performance, but the kind of

performance that can be validated by accident statistics in the long run. For

example, the effectiveness of existing braking and handling capability has not

been definitely established in a real world context, much less the need for any

changes. This is admittedly a difficult area in which to do research; there

are very difficult conceptual problems. It is here, especially, that an

interdisciplinary approach is needed.

Need for Greater Quantity of Data

Over the years, the Safety Administration has done an admirable job

of developing in-depth studies (referred to as multidisciplinary accident

investigations) of limited numbers of accidents, providing some information on

how effectively certain designs may be functioning in specific instances. On

the other hand, these special studies have not adequately revealed from a

national viewpoint safety effectiveness on a representative basis. Thus, the

accident teams which are employed for these in-depth studies can usually give

a reasonably accurate description of any one accident -- and sometimes its

causes or at least the causes of the injuries -- but they are not satisfying

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our current pressing need for a comprehensive estimate of the nationwide

accident picture.

A detailed and highly precise description of any one accident cannot

by itself reveal where the overall priorities lic. There are three reasons

why accident data must be collected in great quantity: First, there is considerable variability in the injury resulting from accidents that are, on the

surface, similar; second, some accident features are quite infrequent and thus

comparisons are often based on so little data they are unreliable; and third,

we have to account for so many factors which can affect the outcome of each

accident.

The first of these reasons -- variability in injury among similar

accidents -- is seen when some people can get out of a total wreck and walk

away with only minor injuries while in other crashes people sometimes die

even though the car is so little damaged it can be driven away. A great

number of crashes must be examined so that the entire range of injuries in

any one type of crash can be accounted for.

secondly, certain events are relatively rare because most accidents

are of comparatively low intensity and the injuries are of correspondingly

low grade. It has been common to combine the counts of severely injured cases

with the counts of fatalities in order to get a large enough total count to

allow reliable comparisons to be made. Furthermore, some factors of interest

-- such as restraints -- have had a relatively low rate of usage so not many

cases have been available for investigation. It was only until B. J. Campbell,

at North Carolina, was able to examine a few hundred thousand cases that he

could find enough applicable ones to reliably detect the profound effect of the

lap belt on the fatality rate -- as distinguished from its effect on the rate

of severe injury or the rate of combined severe-plus-fatality. The base

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fatality rate is quite a bit less than one percent; he found an overall 70

percent reduction in that rate in the lap-belted cases.

The third reason for needing a lot of data is the presence of

numerous variables which affect the accident. The art of doing research

and arriving at findings and conclusions about any aspect of accident or

injury prevention is still fairly experimental. It is experimental because

we do not have unequivocal, established scientific methods to cope with the

present accident data. The reason for this is most of it fails to satisfy

the basic requirements of analysis: that comparisons be made on an “all

else equal” basis. By “all else equal” I mean that conclusions about the

effectiveness of, say, the side guard beam must be made on data from crashes

involving the same kind of vehicles in the same kind of trajectory with the

same kind of people at risk, etc. However, given the diversity of vehicle

models, it takes a lot of accident chasing to find enough crashes of the

same type, of the same severity, and with the same type of vehicles and

drivers, etc. -- that is, in which all else is equal. Mathematical adjustment of the data can take care of some confounding of variables in the data,

but to be confident a considerable degree of representativeness in the original data is still needed.

Not the least consideration for achieving the proper representativeness of data is that there should be standardized definitions and protocols used

by all the investigating agencies. Since a future investigator will query the

data file as a microcosm of the universe of accidents, it would be most disagreeable that cases which are essentially similar were described in the same

file differently only because the data were collected by different agencies

using their own interpretations.

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Need for Scientific Sampling

Not only is an increased quantity of data required but the sampling

of the accident universe must be by sophisticated protocol. The last of the

three reasons given above implies the need for a disciplined approach to the

data, to avoid ending up with data which are biased in the factors underlying

them. That requires a scientific approach to data collection, not just pouring more dollars into it and cranking Up the administrative machine to get a

bigger program going but doing it in the same old way. Data gathering

programs must be designed by the same people as will design the analyses that

will be applied to the data. No less expertise than the Census Bureau applies,

or the Gallup Poll, will suffice. Fortunately, NHTSA has been bringing in

very competent people of late, people who know that a data collection scheme

must be designed from the start with the method of analysis of the resulting

data a key determiner of how the data should be gathered.

It is the Government Who Should Collect Data

Mass accident data acquisition, processing, analysis, and broad

scale distribution requires great effort and much resource. Only the federal

government has the necessary resource and easy access to the agencies which can

supply information. Furthermore, it seems that it is the responsibility of the

federal government to assemble data which will allow an accurate public

of the real dimensions of the crash and injury problem on our highways.

We appreciate the difficulty of developing and implementing a

scale, comprehensive plan for the acquisition of detailed data on motor

review

large

vehicle

related injuries and fatalities. We are aware that the Safety Administration

has over the past several years developed and implemented a portion of such a

plan which is related to fatalities. This effort has resulted in what is known

-130-
as the “Fatality Analysis File. ” We believe that data from most of the 50

states is going into that file and are hopeful that all interested parties

will have access to that file in order that we all may comprehend the true

and detailed dimensions of the fatality problem in the United States.

The Safety Administration has also requested funds for a large

scale field survey of automobile accidents in which crash recorders would be

employed. The data from this program is equally important to that from the

Fatality Analysis File and would provide an accurate determination of the

crash speeds at which the several levels of injury and fatality occur and

can be employed as a basis for defining the performance levels needed in

crashworthiness standards. We support a crash recorder program.

Certain fundamental questions cannot be answered without first

having an adequate base of public data: What do we really know about the need

for increased performance -- increased performance on the types of test criteria in the rules -- based on what is happening out there on the highway?

What will be the effect on injury at lower speed levels when systems designed

for a high speed compliance test are used? What are the proper speed levels

to target for? While accident data are important, they are of course insufficient in themselves; other questions must still be considered: Can we mass

produce these cars to provide such protection at reasonable cost? Should we

approach an increased performance level in one massive jump or would we be

better served to work toward it incrementally? What lead times are required

to achieve these goals? These are obvious questions that should be considered

before such rules are proposed.

In summary, we believe it is necesary to greatly expand accident data

collection, in a well-disciplined scientifically devised program. Crash recorders cannot supplant an accident investigation program. Crash recorders will

-131-
be most useful in research projects whose ends specifically require the

dynamics information which only such a tool can provide rather than in general

data collection programs. There is a great challenge to undertake new studies

of need in the accident avoidance area; indeed, new concepts, of pragmatic

utility and based on what is actually happening on the roads, are needed in

order to get a grasp on the whole issue of vehicle control and its relation

to accidents. It is the government which has the responsibility and the resources for carrying out such programs.

.

-132-
APPENDIX K

POSITION STATEMENT

ON AN

EX1⁄4AMDED. LOW-COST NATIONAL ACCIDENT DATA COLLECTION PROGRAM

J.R. Cromack

B.J. Campbell

L. Patrick

B. O’Neill

February 7, 1975

-133-
POSITION STATEMENT

ON

AN EXPANDED, LOW-COST NATIONAL ACCIDENT DATA COLLECTION PROGRAM

February 7, 1975

J. Robert cromack~ Southwest Research Institute:

B. J. Campbell. Highway Safety Research Center,

University of North Carolina; Lawrence Patrick,

Wayne State University; Brian O'Neill, Insurance

Institute for Highway Safety.

present real-world accident data have some deficiencies and

limitations for both researchers and policymakers. Despite these

limitations, much progress has been made on the basis of these data

and useful information will continue to be obtained from these

sources. However, much can and should be done to improve realworld accident

One major

scale accident

data.

contribution would be the development of a large

data base, possibly modeled on the data base

developed at the Highway Safety Research Center of the University

of North Carolina. This would require the upgrading of police

accident reporting in a number of states and combining the data

into a single base that could be assessed both by researchers and

policymakers. Ideally, real-world accident data in such a base

should include a measure, or measures, of both crash and injury

severity.

At the present time the only available measure of crash

severity is obtainable from the vehicle deformation or crush

appropriately defined in relation to the manner of damage. Crash

severities derived from vehicle deformation or crush can, however,

only be compared among vehicles of the same make and model. It

is possible that future research will enable the grouping of

similar types and styles of vehicles with respect to crash

-134-
Appendix K

Page 2

severities so derived, but at present there are no strong

objective data to support such comparisons. Additional

controlled laboratory type experimentation is needed to

verify crash severity measures obtained from vehicle deformation

or crash.

Meanwhile there are additional descriptors of real-world

accidents that could be valuable to both researchers and

policymakers. Crash recorders could provide such additional

data. It seems likely that sophisticated recorders will

continue to be too expensive to be deployed in the very large

numbers needed to substantially augment present real-world

data. Serious efforts should be devoted towards the development

and large scale deployment of very inexpensive crash recorders

that are designed to record a small number of Parameters that

can be related to the severity of the crash.

The present measures of injury severity obtained from police

accident reports are far from satisfactory and considerable

efforts should also be devoted to upgrading these measures.

Ideally, injuries should be classified either by the Abbreviated

Injury Scale and its derivatives such as the Injury Severity

Score or other appropriate injury scales.

A better understanding Of the nature and effect of traffic

accidents can result from an expanded low Cost, well planned

National Accident Data Collection program. The increased

availability of data so derived will provide a higher confidence

in the results derived from analysis of these data. It should be

a major goal of such an effort to investigate the correlation

between injury and damage, a topic presently not addressed due

to inadequate data, but one that promises Significant Clarification to the problem of injury causation.

-135-
SOUTHWEST RESEARCH INSTITUT E

8500 CULEBRA ROAD • POST OFFICE DRAWER 28510 . SAN ANTONI0, TEXAS 78284

February 7, 1975

Mr. Howard P. Gates, Jr.

Economics and Science Planning

1200 - 18th Street, NW

Washington, D. C. 20036

Dear Mr. Gates:

Enclosed is the approximate

on the assigned ISsue No. 2. In the

concensus of the persons working

interest of time, I am sending you

this document without final approval from each of the members. They

will, however, receive copies of this letter and should they object too

strenuously to any of the final changes or corrections, I feel certain

you will hear from them.

In all fairness to them, I must state that I added the last

paragraph based on my own convictions. It probably represents (at

least in general) their views but this is the major divergence from the

last draft position statement that was circulated. Incidentally,

Larry Patrick did not have an opportunity to comment on the position

statement after making several original contributions at our meeting

on January 17.

None of the participants indicated an intention to take a position

on Federal funding or inducements. Again, it was a pleasure to work

with you and the other individuals at the workshop. I look forward to

future meetings.

Sincerely,

J. Robert Cromack, Manager

Vehicle Safety Section

Department of Special Projects

Automotive Research Division

JRC:mr

Enclosure

cc: Lawrence Patrick

B. J. Campbell

Brian O'Neill

SAN ANTONlO, HOUSTON, CORPUS CHRISTI, TEXAS, AND WASHINGTON, D .

-136-
POSITION STATEMENT - ISSUE 2

Present real-world accident data have some deficiencies and

limitations for both researchers and policymakers. Despite these

limitations, much progress has been made on the basis of these data

and useful information will continue to be obtained from these sources.

However, much can and should be done to improve real-world accident

data.

One major contribution would be the development of a large

scale accident data base, possibly modeled on the data base developed

at the Highway Safety Research Center olf the University of NOrth Carolina.

This would require the upgrading of police accident reporting in a number

of states and combining the data into a single base that could be assessed

both by researchers and policymakers. Ideally, real-world accident data

in such a base should include a measure, or measures, of both crash and

injury severity.

At the present time the only available measure of crash severity

is obtainable from the vehicle deformation or crush appropriately defined

in relation to the manner of damage. Crash severities derived from

vehicle deformation or crush can, however, only be compared among

vehicles of the same make and model. It is possible that future research

will enable the grouping of similar types and styles of vehicles with

respect to crash severities so derived, but at present there are no strong

objective data to support such comparisons. Additional controlled

laboratory type experimentation is needed to verify crash severity

measures obtained from vehicle deformation or crush.

Meanwhile there are additional descriptors of real-world accidents

that could be valuable to both researchers and policymakers. Crash

recorders could provide such additional data. It seems likely that

sophisticated recorders will continue to be too expensive to be deployed

in the very large numbers needed to substantially augment present realworld data. Serious efforts should be devoted towards the development

and large scale deployment of very inexpensive crash recorders that are

designed to record a small number of parameters that can be related to

the severity of the crash.

The present measures of injury severity obtained from police

accident reports are far from satisfactory and considerable efforts

should als o be devoted to upgrading these measures. Ideally, injuries

should be classified either by the Abbretiated Injury Scale and its

derivatives such as the Injury Severity Score or other appropriate

injury scales.

-137-
A better understanding of the nature and effect of traffic

accidents can result from an expanded low cost, well planned National

Accident Data Collection program. The increased availability of data

so derived will provide a higher confidence in the results derived from

analysis of these data. It should be a major goal of such an effort to

investigate the correlation between injury and damage, a topic presently

not addressed due to inadequate data, but one that promises significant

clarification to the problem of injury causation.

-138-
APPENDIX L

RESOLUTION

OF

THE NATIONAL MOTOR VEHICLE SAFETY ADVISORY COUNCIL

November 14, 1974

-139-
A Resolution of the

National Motor Vehicle Safety Advisory Council

(A body advisory to the Secretary of Transportation)

November 14, 1974

Whereas, analysis of the cost/benefits of revising standard

208 to require passive restraints has produced limited field

evidence of the life saving value of passive restraints, including air bags; and

Whereas, the analysis indicates that mathematical projection

and tests with dummies do not predict with sufficient accuracy the

potential value of these restraints in actual use; and

Whereas, there is likelihood that indignation over installation of passive restraints may eventually result in public pressure

for the removal ‘of such restraints after huge investment is made

in them, as in the case of the seat belt interlock; and

Whereas, the mandated addition of yet another costly feature

to new automobiles would be a financial hardship to the American

consumer who must depend on automobiles for transportation;

therefore be it

RESOLVED, that this Council recommends that the Secretary make

a concerted effort to come to an agreement with industry on a plan

that would result in increased passive restraint usage on the road

and defer a call for rulemaking with respect to passive restraints

until such time as further actual experience with them on the

highways proves that they will reduce deaths and injuries.

-140-
APPENDIX M

THE NEED FOR STANDARD1ZATION

IN REPORTING COLLISION DAMAGE AND INJURY

IN TRAFFIC ACCIDENTS

J. Robert Cromack

January 16 & 17, 1975

-141-
-142-
———.— —

-143-
OF DAMAGE, THE TYPE OF DAMAGE

OBJECT, SUCH AS POLE, CAUSING

95% OF THE TIME
-145-
-146-
APPENDIX N

REGULATORY RULEMAKING

BASED ON LESS THAN TOTAL INFORMATION

David Morganstein

CENTER FOR AUTO SAFETY

and

L.A. Goldnuntz

ECONOMICS & SCIENCE PLANNING, INC.

February 21, 1975

(date of receipt)

-147 -
REGULATORY RULEMAKING

BASED ON LESS THAN TOTAL INFORMATION

David Morganstein, Center for Auto Safety,

and L. A. Goldmuntz, Economics & Science Planning, Inc.

Received February 21, 1975

Estimation of the costs and benefits expected from regulatory

programs is complicated by a lack of precise information. Several

areas where a lack of knowledge exist are: the methods to be used

by those regulated to meet the requirements; the efficacy of the

methods chosen; the details which enter into the pricing effort of

changes brought about by the regulation; alterations in the initial

conditions which may occur over time, causing unpredictable

variations in costs or benefits; the effectiveness of the regulation

in achieving the desired benefits; and the impacts the regulation

might have in other areas.

One subject not frequently addressed is the variation of the

process to be regulated. If a population characteristic is timevarying, the potential benefits may be similarly varying. In such

a situation, the possible conflicting conclusions that might be

arrived at must be considered. There are well known tools, such

as decision theory, which may provide a better conclusion than

some undefined subjective process. Thus, the cost, the need or the

value of additional data collection can be evaluated in light of its

potential for clarifying the issues.

Nevertheless, governmental expectations are sufficiently high

and the public demand sufficiently intense that programs may

proceed even though complete information is unavailable or unattainable. After programs have been in place for some period, improvements

-148-
— —

may be realized more slowly than initial expectations. Ensuing

discussions are polarized around industry and the regulatory

agency: Is industry using unnecessarily expensive methods, and

not choosing methods most likely to meet the intent of the

regulation? Or on the other hand, are bureaucrats acting to

enlarge their domain or justify their existence as a regulator?

Or is there a lack of communication between industry , the

regulators and the public so that there is little understanding

of the issues and therefore little progress in resolving them?

Advocates may reference controlled laboratory experiments to

estimate the efficacy of a regulation. They argue that the learning process will improve the methods used to meet the intent of the

regulation and lower costs. Cynics question the extent to which

laboratory experiments represent the real world. When cynics argue

that the introduction of a new technology has a price tag which

will ultimately be paid by the public, the advocates counter that

the withholding of such technology has its own price tag. Clearly,

there are societal costs to be borne without the protection of the

regulation, with inadequate regulation or with excessive regulation.

These issues have no general answers but require analysis case by

case at each stage of the development of the regulation.

Analyses of the complex issues can best be carried out by a

number of independent professional sources working independently.

These efforts should then be compared, and the analyses and reasons

for proceeding or not proceeding with a suggested program should be

subject to public scrutiny. The consumer is potentially victimized

when information is in the hands of any one monolithic organization,

be it a regulatory agency or an industry. The consumer may also tend

to be victimized by oversimplified sensationalized commentary by

either side to the debate.

-149-
Regulatory Rulemaking

Appendix N p. 3

The consumer has to rely on the different perspectives within

society to accomplish the various analyses that expose the issues.

We believe this pluralism can then lead to modifications of

various points of view and perhaps lead to an eventual crystallization of the issues in a form that can be more readily understood by

the public. At this point, it is essentially a public or political

decision as to whether to proceed or not to proceed with any given

regulatory program. The public interest is served best by having

the issues fully explored from many points of view by many

independent sources in estimating the potential costs and benefits

of proposed regulatory programs.

-150-
—.—— .——

.

APPENDIX o

AUTOMOBILE COLLISION DATA WORKSHOP:

AGENDA

SCHEDULED PRESENTATIONS

SALIENT RESIDuAL ISSUES

January 16 & 17, 1975

-151-
—-— —

TENTATIVE AGENDA

AUTOMOBILE COLLISION DATA WORKSHOP

Part I. Data Requirements.

(a) Collision data needed for the design of crashworthy

passenger cars including the restraint system, and to

permit compliance testing; kinds of information, their

relative importance, and precision required.

(b) Collision data needed for rational regulatory rulemaking;

kinds and amounts of information, priorities, precision.

(c) Adequacy of the existing collision data base and the

utility of data being gathered by current methods.

(d) Statistical requirements: rate at which data should be

gathered to be timely in the environment of a temporallyvarying car-design population; the data file size to

assure statistical significance when divided into cells of

interest; time to accrue the required data file as a

function of sampling rate; statistical adequacy of current

and proposed programs.

(e) Dollar-equivalent benefits of adequate data; costs of not

having data or using incorrect data.

Part II. Data Gatherinq Techniques and Programs.

(f) Crash recorders: capabilities, costs and limitations of

alternative designs and programs.

(g) Accident reporting: extent, accuracy, costs and limitations; potential and cost of improving reporting accuracy.

(h) utility, cost and limitations of computer crash simulation.

-152-
Tentative Agenda

Page -2-

(i) Derivation of crash data statistics through correlation

of laboratory crashes with real world experience; clinical investigations; adequacy, accuracy, cost and

limitations of these approaches.

Part III. Public, Legal and Legislative Reactions.

(j)

(k)

(l)

The potential impact of crash recorders on tort claim

settlement.

The reaction of public interest groups to

collision-data-gathering programs

The legislative history of collis

●

ion data

alternate

gathering

proposals and programs.

-153-
SCHEDULED PRESENTATIONS ..— —....—- —

AUTOMOBILE COLLISION DATA WORKSHOP .-. . . . . . . . —.. ..-. . -— .—..— ---- ..—— -—-. .— -

January 16, 1975

——- DATA REQUIREMENTS

“Mass Accident Data Acquisition and Why

John Versace, Ford Motor Company

“Inadequacy of Accident Data to Conduct

Robert Cromack, Southwest Research

“Need for Better Crash Data”,

Brian O'Neill, Insurance Institute

“Collision Data Required to Improve and

It’s Needed”,

Meaningful Research”,

Institute

for Highway Safety

Evaluate Safety”,

Lawrence Patrick, Wayne State University

—

“How Data Fits Into the Rulemaking Process”,

James Hofferberth, National Highway Traffic Safety Administration.

“Adequacy and Limitations of Current Data”,

Marie Eldridge, National Highway Traffic Safety Admin.

DATA GATHERING TECHNIQUES AND PROGRAMS

“A Discussion of Data Gathering Systems”,

Edwin Kidd, Calspan Corporation

“How to Make Crash Recorders Support Other Data Collection Programs”

B. J. Campbell, Highway Safety Research Center, U. of N. C.

“Crash Recorders: A Solution Seeking A Problem?”

James O’Day, Highway Safety Research Institute, U. of Mich.

“NHTSA Crash Recorders” ,

Lynn Bradford, National Highway Traffic Safety Administration

“Automotive Tape Recorder”

Charles Conlon, AVCO Systems Division

“All Solid State Triaxial Accelerometer for Crash Testing”,

Louis Roberts, Transportation Systems Center

-154-
——

Economics

& Science

Planning 1200 18th Street, N.W. Washington, D.C. 20036 Telephone: 202-223-8444

January 20, 1975

AUTOMOBILE COLLISION DATA WORKSHOP

January 16-17, 75

A number of major issues surfaced at the January 16, 1975

Automobile Collision Data Workshop. The following people have

agreed to write brief position papers on these issues and to

forward them to Economics & Science Planning, Inc., before

February 1, 1975:

ISSUE 1

Estimate

accident data

From the

(Working

the potential societal cost of not having better

than available from current resources.

point of view of the automobile manufacturer:

separately)

o John Versace, Ford Motor Co.

o Richard Wilson, General Motors Corp.

From the point of view of the regulator:

o James Hofferberth, NHTSA

ISSUE 2

What are the advantages of an expanded low cost national

accident data collection program that might provide 600,000

to a million reports per year? How would such a data program

be organized? Are there any models for such a data program?

What Federal funding or inducements would be appropriate to

achieve it?

(Working together)

o Brian O'Neill, Insurance Institute for Highway Safety

o Lawrence Patrick, Wayne State University

o B. J. Campbell, Highway Safety Research Center

o Robert Cromack, Southwest Research Institute

Cable . . . ESPINC

Telex . . . 248482

-155-
Auto Collision Data Workshop

January 20, 1975

Page -3-

ISSUES TO BE CONSIDERED BY THE

OFFICE OF TECHNOLOGY ASSESSMENT

IN ITS RESPONSE TO THE HOUSE

APPROPRIATIONS COMMITTEE ARE

THE FOLLOWING:

.

1.

2.

3*

4.

How much has NHTSA spent in each of the past three years to

gather accident data? Is that data sufficient, or is

further data on the characteristics of automobile collisions

necessary for effective NHTSA standards-setting? If the

existing data base is inadequate; in what ways is it inadequate?

An evaluation of the type of data being produced by existing

crash recorders and an explanation of how this data is being

used by NHTSA should be conducted.

If the data base is inadequate, how might an adequate data

base be obtained and what are the consequences associated

with obtaining the data in different ways (including the

possibility of not obtaining the necessary data)? The cost

effectiveness of the crash recorder and the crash impact

approaches proposed by NHTSA should be examined.

Secondary consequences of implementing these or other

programs should be identified and evaluated. Examples of

these secondary consequences include legal questions

associated with the existence of actual physical data from

an accident and the potential value (to driver training

programs) of a knowledge base concerning how drivers actually

respond in accident situations. For each type of approach

investigated, the implementation costs to the Federal

Government, industry and consumers should be identified.

-156-
——.——— .— --

Auto Collision Data Workshop

January 20, 1975

Page -2-

——ISSUE 3

Define the role of crash recorders in capturing field data

needed to evaluate and calibrate accident investigators reports,

crash tests, and crash simulation.

* Gene Mannella, NHTSA

* James O’Day, Highway Safety Research Institute,

University of Michigan

* Edwin Kidd, Calspan Corporation

IssuE 4

what is the statistical rationale for the number of recorders

proposed for procurement and installation by NHTSA? Is the number

appropriate to the calibration uses described in 3 above? injury

and fatality prevention rulemaking? damageability rulemaking or

assessment?

* Gene Mannella, NHTSA

* Don Mela, NHTSA

IssuE 5

Reliable data is sometimes unavailable to the extent desired

when a regulatory action may seem to some to be desirable. What

general policy guidelines if any can be developed to guide

regulatory actions in an environment of imperfect data.

* David Morganstein, Center for Auto Safety

* Lawrence Goldmuntz, Economics and Science Planning

-157-
LETTER FRQM JOHN GARRETT

CALSPAN CORPORATION

AND

ATTACHMENT

March 12, 1975

-159-
1

!,

. . . .

...U-.....M “.—.**

- . . .

-

~w~.~~’~

. —-: An. —, .., ...—-,.ri— ,- , - --- ..W

March 12, 1975

Air Mail

Dr. Lawrence Goldmuntz

Economics and Science Planning

1200 18th Street, N.W.

Washington, D.C. 20036

Dear Dr. Goldmuntz:

Following our telephone conversation about two weeks ago, I gathered

some material on our use of police photography for estimation of vehicle damage

severity and/or speed, as I had agreed. The material is attached to this letter.

To provide background, and some additional detail, I have summarized relevant

information below.

We first became concerned with the problem of assessing accident

severity in our Automotive Crash Injury Research (ACIR) program in the early

to mid-1950’s. At that time, we developed an accident Severity Index (Attachment A) based on damage to the vehicle. The police provided interior and exterior photographs of the accident vehicle but the ratings were made by a small

staff of trained Calspan (then Cornell) personnel. This procedure tended to

minimize the inter-coder variability that would have resulted if thousands of

police had rated the accidents. Also, it was not necessary to train police to

code, but only to take the proper photographs. Thus, training costs were kept

low.

Accuracy of ratings were further assured through the use of fairly extensive computer edit procedures. “Illegal” (impossible) codes resulted in a

case being returned for checking. Consistency checks also were used, i.e., a

case that was rated minor could not have severe overall damage to the car

elsewhere or any damage to basic structure such as the chassis. Low probability

events that were inconsistent with the severity also required a recheck of the

case. Thus, a fatality in a case where the severity rating for the vehicle was

minor, warranted a check. Some corrections were made automatically, but many

errors required a recheck.

The reliability of rating procedures also was checked periodically by

ACIR to ensure that rater variability was kept to a minimum. A copy of one report

on this subject (Attachment B) is enclosed.

*

1’ -160-
Dr. Lawrence Goldmuntz

March 12, 1975

Bob Campbell later developed the TAD scale which is used by police in

North Carolina and several other states. Here, all ratings are made by police

in the field. Bob’s studies have shown that they do rather well, but I think that

I would prefer the additional control which our system provides.

The Collision Deformation Code (CDC) developed by G.M. generally

succeeded the earlier systems for use by many researchers and the in-depth

teams. In some ways this always seemed odd to me since the in-depth teams had

measurements of the actual vehicle damage which were more accurate than the CDC.

This scale clearly is too complicated for police use in the field. However, we

have compared CDC ratings obtained by our personnel from police photographs with

those obtained by an experienced invetigator rating the CDC from actual inspection and measurement of the vehicle. The results were quite good (Attachment

C, pages 37-56) and we would have confidence in ratings provided by such a system.

Again, ratings were made by a small staff of Calspan personnel with appropriate

checks to maintain accuracy.

We later summarized available data from Calspan crash tests in a first

attempt to develop an aid for estimating speed from vehicle damage (Attachment D).

The amount of useful data was limited and the approach was dropped when additional

inputs were not forthcoming.

Development of the SMAC program by Ray McHenry permitted accurate estimates of impact speeds, but requires such information as vehicle damage, point

of impact and vehicle rest positions. Use of the Calvan simplifies the collection

procedure for police and ensures accuracy. Ray is now working on a simplified

version of the START program for SMAC which, it appears, may provide reasonably

accurate speed estimates. A brief description appears in Attachment E.

Data collection cost was another point that we discussed. The cost of

our most recent program to collect police photographs (last year) was approximately

$5,000 for 1,200 cases. Costs include only purchase and processing of film. We

have purchased relatively inexpensive Instamatic cameras ($20-25) for police use,

with good results. Generally, one camera per car is needed.

In our discussion, YOU also mentioned the possible use of templates for

measuring the vehicle damage photographed. We explored this, but it is quite

difficult to do without an overhead shot of the vehicle or the use of photogrammetry. If we go that far, then I believe that the Calvan would be competitive

in terms of cost and would provide far better data.

-161-
——

Dr. Lawrence Goldmuntz

March 12, 1975

This has become a rather lengthy letter with many attachments, but

since I agree that the use of police photographs can provide good vehicle

damage/speed data, I have tried to provide what useful information I can. It

may still be sketchy for your purposes, however. If so, I will be pleased to

provide any additional information that we have available, ‘

Sincerely,

JWG:jem

Attachments

-162-
L .1 ,.L ., .

Introduction

Discussion of Rating Metho ——. -.—.—d
pants. Accident severity and survivability are rated semi -independently

although in fact they are inextricably related. Broadly speaking, accident

severity is classified in terms of the type, extent and area (side, rear,

etc. ) of the car damaged, whereas survivability is classified in terms of

occupant environment, i.e., whether there is collapse or invasion of the

compartment . Accident severity and survivability are not mutually exclusive categories, as is shown in the gross relationship between c a r damage,

accident severity, and survivability.

In classifying accident severity a six-point scale (below) ranging

from minor to extreme is used. In descriptive terms, damage ranges from

denting and scratching of surface metal to complete disintegration or crushing of the car. Thus, the accident severity rating rises progressively as

damage increases and more of the structural elements of the car are affected.

Accident Severity and Survivability Scale

Car Damage

0

Sheet Metal Damage

No damage to basic structure;

no invasion of compartment.

Structural elements progressivel y

involved; compartment may, o r

may no t$ be invaded .

Complete Destruction

Accident

Severit y Survivability y

Minor

Mode rate

Moderately

Severe

Sever e

Extremel y

Severe ”

Extreme

Survivable

Survivable

Survivable,

Questionable

or Partial

Survivable,

Questionable,

or Partial

Survivable ,

Questionable,

Partial, or

Non -Survivable

Non-Survivable

-164 -
When an accident is rated minor or mode rate in severity it is conside red survivable. Moderately severe, severe or extreme 1 y severe acci -

dents may also be survivable, or survivability may be rated as questionable or partial. Extremely severe accidents may also be classified as nonsurvivable. Extreme accidents are always regarded as non- survivable be -

cause they involve almost complete destruction of the

description of both accident severity and survivability

sections which follow.

Accident Severity

o Minor

car. A more detailed

is provided in the

Damage is most often confined to the sheet metal surface of the car

although bumpers may be slightly dented, headlights or taillights broken,

radiator grill bent or broken, ornamental molding torn free. When forces

are applied to sheet metal, damage may be de scribed in such terms as

“small dent”, “slight deformation", scratches ”, etc. Such damage is

con side red minor whether a small or large area of the car is affected.

Minor severity accidents never involve structural components of the car.

l Mode rate

Damage most often involves sheet metal, but such structures as

bumpers, bumper guards, or radiator grill may be damaged. Sheet metal

or grill damage may be described as “slight buckling”, “pushed in’

“crumpled”, or “torn”. For stronger components -- such as a steel burn -

per -- descriptive phrases such as “large dent”, “twisted”, or “bent”

might be used. In accidents of mode rate severity, structural components

of the car are undamaged.

l Moderately Severe

Damage involves forces sufficiently great so that stronger structural elements as well as sheet metal are affected. Usually sheet metal

begins to collapse and, depending on the area of impact, comer posts,

center posts, or chassis frame may be deformed.

l Severe

Damage in this category always involves collapse or marked displacement of structural elements, as well as c rushing or telescoping of

sheet metal. This grade of accident severity often involves penetration of

compartment are as ‘either as a result of direct impact,

displacement of other parts of the car due to impact or

or as a result of

overturn.

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● Extremely Severe

Damage to the impacted area in these accidents is very extensive.

Structural elements and sheet metal in the affected areas are gene rally

crushed ● There is considerable telescoping of the impacted area, and

there is usually some invasion or collapse of the compartment.

● Extreme

This category is reserved for accidents so severe that the automobile involved is almost completely demolished, and often is scarcely recognizable as an automobile. Damage may be de scribed as almost complete

disintegration or crushing of the entire car. Photographs of extreme dam -

age are not provide d in the figure illustrating accident severity because all

damage beyond that illustrated for extremely severe is considered extreme.

Survivability

The concept of survivability is based on the assumption that survival is dependent on the compartment area remaining essentially intact.

In rating survivability, it is recognized that other forms of protection --

interior redesign, padding, lap belt and harness, or even other devices as

yet not available -- may be required in order to fully capitalize on the potential survivability afforded by the compartment. Without a reasonably

intact environment, however, there is no assurance that occupants could

survive even with other protective devices. The criteria used in determining survivability, there fore, are the degree of compartment collapse

and its influence on the normal seated position areas, i. e. , whether there

would be sufficient space for Survival if all seats had been occupied by

persons seated in a normal, upright position, and all occupants had remained in their seats. In brief, whether the area surrounding each seat

in the car could still hold an upright occupant.

Data concerning the actual fate of automobile occupants indicat e

that many occupants die in accidents that are relatively mild and, conversely, some occupants survive even when the car is demolished. Although all cars in the ACIR study contain at least one occupant, in classifying survivability the presence or absence of occupants, as well as the

fate of those occupants actually present in the car, is ignored. In effect,

the car is rated without considering the number of occupants or whether

they lived or died. Thus, occupants may survive a non- survivable accident,

or may die in a survivable accident.

A "survivable ” rating signifies that the compartment (occupant are a )

was essentially intact and that there was no c rushing or invasion of th e

compartment . As the compartment area collapses or is progressivel y

invade d by surrounding structure, survivability may be classified as survivable, questionable, partial, or non- survivable. Survivability categor -

ies and the appropriate accident severity categories are described below.

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—.— — —. —-.

● Survivabl e

photograph - severe;

● Partiall y

This category

Rear - extremely severe; Rollover - severe. )

Survivable

is used when one or more, but not all) seated posi -

tions are compressed to such a degree that it is considered non-survivable

for a normally se ate d person. This classification may be used only with

mode rate 1 y severe, severe, and extremely severe accidents. (Rated

partially survivable: Side photograph - extremely Severe.)

● Non-Survivable

When the entire compartment is compressed Or invaded tO such an

extent that there is insufficient room for an occupant seated upright in all

the normal seating areas, the accident is considered non- survivable.

Extremely severe accidents may be classified as non-survivable, and

extreme accidents must be so classified. (Rated non-survivable: Front

photograph - extremely severe; Rollover - extremely severe. )
Accident Severity and Survivability

Classification

Survivable

Minor

Moderate

Moderately severe

Sever e

Extremely severe

Non- survivable

Extremely severe

Extreme

Partially survivable

Moderately severe

Sever e

Extremely sever e

Questionable survivability

Moderately severe

Severe

Extremely severe

Not Able to Classify

Column 69

Code

1

2

3

4

5

E

F

L

M

N

T

u

v

x

-168 -
4,4 ..,, . . .

FRONT

MINOR

MODERATE

MODERATELY

SEVERE

SEVERE

EXTREMEL Y

SEVERE

-169-
SEVERITY

REAR

./#-’ -

ROLLOVER

MINOR

MODERATE

MODERATELY

SEVERE

SEVERE

ACCIDENT RESEARCH BRANCH

TRANSPORTATION RESEARCH

CORNELL AERONAUTICAL LABORATORY --- —