A11107 nfilSl

PUBLICATIONS

a

v., ^^Z-

(0 Q

NBS SPECIAL PUBLICATION 652

U.S. DEPARTMENT OF COMMERCE/National Bureau of Standards

QC

IGQ

,U57

652

1933

G.2

Damage Prevention

in the

Transportation

Environment

MFPG

34th Meeting
NATIONAL BUREAU OF STANDARDS

The National Bureau of Standards' was established by an act of Congress on March 3, 1901. The Bureau's overall goal is to strengthen and advance the Nation's science and technology

and facilitate their effective application for public benefit. To this end, the Bureau conducts

research and provides: (1) a basis for the Nation's physical measurement system, (2) scientific and technological services for industry and government, (3) a technical basis for equity in trade, and (4) technical services to promote public safety. The Bureau's technical work is per- formed by the National Measurement Laboratory, the National Engineering Laboratory, and

the Institute for Computer Sciences and Technology.

THE NATIONAL MEASUREMENT LABORATORY provides the national system of

physical and chemical and materials measurement; coordinates the system with measurement

systems of other nations and furnishes essential services leading to accurate and uniform

physical and chemical measurement throughout the Nation's scientific community, industry,

and commerce; conducts materials research leading to improved methods of measurement,

standards, and data on the properties of materials needed by industry, commerce, educational

institutions, and Government; provides advisory and research services to other Government

agencies; develops, produces, and distributes Standard Reference Materials; and provides

calibration services. The Laboratory consists of the following centers:

Absolute Physical Quantities^ — Radiation Research — Chemical Physics —

Analytical Chemistry — Materials Science

THE NATIONAL ENGINEERING LABORATORY provides technology and technical ser- vices to the public and private sectors to address national needs and to solve national problems; conducts research in engineering and applied science in support of these efforts; builds and maintains competence in the necessary disciplines required to carry out this research and technical service; develops engineering data and measurement capabilities;

provides engineering measurement traceability services; develops test methods and proposes

engineering standards and code changes; develops and proposes new engineering pracfices;

and develops and improves mechanisms to transfer results of its research to the ultimate user. The Laboratory consists of the following centers:

Applied Mathematics — Electronics and Electrical Engineering^ — Manufacturing

Engineering — Building Technology — Fire Research — Chemical Engineering^

THE INSTITUTE FOR COMPUTER SCIENCES AND TECHNOLOGY conducts

research and provides scientific and technical services to aid Federal agencies in the selection, acquisition, application, and use of computer technology to improve effectiveness and

economy in Government operations in accordance with Public Law 89-306 (40 U.S.C. 759), relevant Executive Orders, and other directives; carries out this mission by managing the Federal Information Processing Standards Program, developing Federal ADP standards

guidelines, and managing Federal participation in ADP voluntary standardization activities; provides scientific and technological advisory services and assistance to Federal agencies; and

provides the technical foundation for computer-related policies of the Federal Government.

The Institute consists of the following centers:

Programming Science and Technology — Computer Systems Engineering.

'Headquarters and Laboratories at Gaithersburg, MD, unless otherwise noted; mailing address Washington, DC 20234. ^Some divisions within the center are located at Boulder, CO 80303.
HATIONAI. BOTEAU

OF STANDARDS

I.I2nAJ!Y JJ" 11^ . MAY 31 1983

Damage Prevention in the ^^^^ Transportation Environment ^

Proceedings of the 34th Meeting of the

Mechanical Failures Prevention Group

held at the National Bureau of Standards,

Gaithersburg, Maryland, October 21-23, 1981 -

-

Edited by:

T. Robert Shives

Fracture and Deformation Division

Center for Materials Science

National Measurement Laboratory

National Bureau of Standards

Washington, DC 20234

This meeting was sponsored jointly by NBS and the:

Office of Naval Research

.S. Department of the Navy

Arlington, VA 22217

Naval Air Systems Command

U.S. Department of the Navy

Washington, DC 20360

National Aeronautics and Space Administration

Goddard Space Flight Center

Greenbelt, MD 20771

U.S. DEPARTMENT OF COMMERCE, Malcolm Baldrige, Secretary

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director

Issued April 1983
Library of Congress Catalog Card Number: 83-600521

National Bureau of Standards Special Publication 652

Natl. Bur. Stand. (U.S.), Spec. Publ. 652, 349 pages (April 1983)

CODEN: XNBSAV

U.S. GOVERNMENT PRINTING OFFICE WASHINGTON: 1983

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402

Price $8.00

(Add 25 percent for other than U.S. mailing)
PREFACE

The 34th Meeting of the Mechanical Failures Prevention Group was held

October 21-23, 1981 at the National Bureau of Standards in Gai thersburg,

Maryland. The program was organized by the MFPG Technical Committee on Design under the chairmanship of Jesse E. Stern of Trident Engineering

Associates. Where possible, the papers in these proceedings are presented as submitted by the authors in the form of camera ready copy.

Limited editorial changes, some retyping, and some photographic reduction were required.

Support of the National Bureau of Standards, the Office of Naval

Research, the Naval Air Systems Command, and the National Aeronautics

and Space Administration is gratefully acknowledged.

'Appreciation is expressed to Kathy Stang of the NBS National Measurement

Laboratory for handling financial matters and to Sara Torrence and Greta

Pignone of the NBS Public Information Division for the meeting and

hotel arrangements.

T. Robert Shives

Executive Secretary, MFPG

Fracture and Deformation Division

National Bureau of Standards

nr
TABLE OF CONTENTS

PREFACE

SESSION I: PACKAGING FOR THE TRANSPORTATION ENVIRONMENT

1. Allocating Loss and Damage to the Railroad

Transport Cycle

Vetev J. Wong

2. Export Packing in the Marine Environment

J. P. Colletti

3. Packaging Software for Shipment and Storage

B. D. Winn, W, D. Downing and

S. B. Crumi*ine .

4. Packaging for the Transportation Environment

W. Dunoan Godshdll

SESSION II: RESEARCH IN THE RAILROAD INDUSTRY

1. Improved Suspension Designs and Their

Influence on Freight Car Dynamics

P. V, RamaChandran and M. M. ElMadany

2. Development of Small Scale Impact

Simulation Techniques (Abstract only)

J. Chen and N. G. Dagalakis

3. A Method to Detect and Monitor Crack

in Bridge Structures

Jackson C. S. Yang and Manfred A. Eirt

4. Railroad Long-Term Maintenance-of-Way

Planning Technique Development Program

A. Gross

5. Analytical Investigation of Lading

Responses from Various Pulse Shapes

V!. P. ManoSj J. C. Shang and

J, B. Raidt

6. System for Train Accident Reduction - DOT STAR

J. J, Richardson

IV
SESSION III: RESEARCH IN THE RAILROAD INDUSTRY (continued)

1. Freight Car Response Analysis and

Test Evaluation Model (PRATE)

Claire L, Orth and George Kaahadourian

2. The Accident Performance of Tank Car

Safeguards

William G. Meeker

3. Rail Tank Car Impacts

David M. Dancer

4. A Locomotive Evaluator - New Research

Capability Through Simulation

J. V. Mirdbella

SESSION IV: DAMAGE PREVENTION IN THE RAILROAD INDUSTRY

1. Designing for Damage Prevention in

the Railroad Tank Car Industry

Es A. Phillips

2. Performance Testing to Reduce Loss

and Damage

William A. Vidkerman and

W. D. Godshall

3. Field Measurement of the Fatigue Loading

Environment for Railroad Freight Equipment

(Abstract only)

W. Sneed and A. M, Zarembski

SESSION V: DESIGNING FOR TRANSPORTATION OF HAZARDOUS

MATERIALS (NUCLEAR MATERIALS AND WASTES)

1. Truck and Rail Shock and Vibration

Environments During Normal Transport

G. H. LamoreaiiXj A. A. Tmjillo

and C. F. Magnuson

2. The Nature of Transportation Accidents

Involving Radioactive Material Packagings

E. L. Emerson and J. D. McClure

3. Perceived Safety of Transporting Hazardous

Material

s

R. T. Reese and E. W. Shepherd
4. Analysis, Scale Modeling, and Full-Scale

Testing of Shipping Containers for

Radioactive Materials

E. Richard Yoshimura and M. Huerta

5. Response of Radioactive Material Waste

Drums to Accident Environments

R. A, Mai/j G. H, LamoreauXj

L. E. Romesherg and H. R. Yoshimura

6. Design of Packaging for Transporting

Transuranic Contaminated Wastes

L. E. Romesherg^ S. H. Sutherland^

G. E. Lamoreaux and R. G. Eakes

SESSION VI: HIGHWAYS

1. Planning to Prevent Failure in the

Transportation of Hazardous Materials

E, J. Cantitli and Dino Rossini

Z. Cargo Ride Evaluation on a Road Simulator

C. R. Forton

3. Highway Design and Maintenance for

Tomorrow's Traffic

B. M. McCarthy

4. The Failure of Manhole Covers on Tank

Trailers During Rollover

R. D. Ervin

APPENDIX

Attendance List for the 34th MFPG Meeting

MFPG Publications

VI
ABSTRACT

These proceedings consist of 27 submitted entries (25 papers and 2 abstracts) from the 34th Meeting of the Mechanical Failures Prevention

Group which was held at the National Bureau of Standards, Gai thersburg,

Maryland, October 21-23, 1981. The subject of the symposium was damage

prevention in the transportation environment. Areas of special emphasis

included packaging for the transportation environment, research in the

railroad industry, damage prevention in the railroad industry, designing

for the transportation of hazardous materials, and highways.

Key words: Airline environment packaging; hazardous materials transportation; highway design; marine environment packaging; packaging

techniques; railroad environment packaging; shipping; transportation;

transportation damage prevention; trucking environment packaging.

UNITS AND SYMBOLS

Customary U. S. units and symbols appear in some of the papers in these

proceedings. The participants in the 34th Meeting of the Mechanical

Failures Prevention Group have used the established units and symbols

commonly employed in their professional fields. However, as an aid to

the reader in increasing familiarity with the usage of the metric

system of units (SI), the following references are given:

NBS Special Publication, SP 330, 1981 Edition, "The International System

of Units."

ISO International Standard 1000 (1973 Edition), "SI Units and Recommendations for Use of Their Multiples."

IEEE Standard Metric Practice (Institute of Electrical and Electronics

Engineers, Inc., Standard 268-1979).

DISCLAIMER

Certain trade names and company products are identified in order to

adequately specify the experimental procedure. In no case does such

identification imply recommendation or endorsement by the National

Bureau of Standards, nor does it imply that the products are neces- sarily the best available for the purpose. Views expressed by the

various authors are their own and do not necessarily represent those

of the National Bureau of Standards.

VII

SESSION.

PACKAGING FOR THE TRANSPORTATION ENVIRONMENT

CHAIRMAN: JESSE E. STERN

TRIDENT ENGINEERING ASSOCIATES

ALLOCATING LOSS AND DAMAGE TO THE RAILROAD TRANSPORT CYCLE

Peter J. Wong

SRI International

Menlo Park, California 94025

Abstract: This paper presents the results of allocating loss and

damage cost to various elements of the railroad transport cycle. Estimates of loss and damage attributed to linehaul shock and vibration

and flat and hump yard coupling impacts are provided. In addition,

loss and damage estimates are provided for various levels of overspeed

impacts in hump yards.

Key words: Loss and damage; lading damage; freight damage.

INTRODUCTION ^

In calendar year 1978, the Association of American Railroads (AAR)

statistics indicate that North American railroads lost a total of

$304,368,908 in freight loss and damage (L&D) ; this represented

approximately 1.3% of the total gross operating revenues for all

railroads. Industry sources indicate that the indirect costs to

railroads and shippers to process and handle L&D claims may be as much as eight times greater than the direct L&D payments. If this is

true, then the total costs of L&D to railroads and shippers may be in excess of $2.5 billion dollars per year.

There is a current lack of information and understanding of the L&D

costs which can be attributed to shock and vibration (rough handling)

in the transport cycle. In particular, we would like to know how much

L&D can be attributed to railroad yards versus the linehaul. In

yards, we would like to know how much L&D can be attributed to hump

yards versus flat yards, and how L&D increases with impact speeds in

yards. Over the linehaul, we would like to assess the contribution

to L&D of longitudinal train slack-action versus vertical vibration.

This L&D transport cycle information is important to assist in planning the priorities of future L&D countermeasures to investigate the

effects of shock and vibration. Furthermore, this information is

necessary to assess the benefit-cost impact of any specific proposed

countermeasures. Examples of potential areas for countermeasure

development include:

• Countermeasures to reduce L&D due to train slack-action over

3
llnehaul

• Countermeasures to reduce L&D due to vertical vibration over

the linehaul

• Countermeasures to reduce L&D due to overspeed impacts in hump

or flat yards

RESULTS

A systematic methodology was developed to allocate 1978 loss and damage

direct payment costs as detailed in the Association of American Railroads Circular No. FCDP-133 entitled: "Freight Loss and Damage, 1978."

The results of the methodology are presented below.

The 1978 L&D direct payments costs caused by shock and vibration is

estimated to be $101.3 million; $55.7 million is due to yard impacts and

$45.6 million is attributed to vibration and train-slack action in the

linehaul. On a per loaded trip basis the average L&D direct pajrment

associated with shock and vibration is $4.33; $2.38 is associated with

yards and $1.95 with linehaul. Of the $55.7 million due to overspeed

impacts in yards, $22.5 million is associated with hump yards and $30.2

million is associated with flat yards. It is to be noted that 20% of

the switching activity occurs in hump yards and 80% in the flat yards.

The average L&D direct pa5rraent costs per hump yard coupling is estimated to be approximately $0.91. For a hump yard which processes 2,000

cars per day over the hump of which half the cars are loaded, this

implies L&D direct payments costs of $910 per day or $322,000 per year

due to overspeed impacts. The expected L&D direct pa57ment costs per

occurrence of hump yard overspeed impact level is detailed below.

Expected Direct Payment

Overspeed Impact Costs Per Occurrence '

<4 mph $ 0.00

4 - 5 mph $ 0.13

5 - 6 mph $ 1.19

6 - 7 mph $ 3.31 7-8 mph $ 6.49 8-9 mph $10.73

9-10 mph $16.03

>10 mph $22.39

It should be remarked that the direct pa5nnent costs detailed above

represent only a fraction of the total costs and that indirect costs

to the railroad and shipper to process and handle claims can be as

4
much as eight times the direct payment payment costs. Also, it should

be emphasized that the costs which have been calculated are average or mean values (also called expected values in statistics). Therefore,

one must be careful in interpreting these costs. The average cost for

a particular event (e.g., per coupling, per loaded trip) is calculated

by taking the total costs for all events and dividing by the total

number of events. Thus, the costs associated with any particular

occurrence of an event may deviate significantly from the average cost;

the average cost is actually surrounded by a statistical distribution

of costs. For example, we estimate that the average 1978 L&D direct

payment costs per hump yard coupling is approximately $0.91. This does

not mean that a 100 car sample would yield a $0.91 L&D for each coupling; the actual distribution may be 99 couplings having no loss and

damage and one coupling having a cost of $91, for purposes of costbenefit economic analysis, where aggregate statistics are used, the use

of average values should be relatively accurate.

METHODOLOGY SUMMARY i^--.

The AAR each year provides aggregate statistics on L&D. In particular,

in 1978, the L&D pajnnents for North American railroads amounted to

$304,368,908. For reporting purposes, Ref. 1 lists L&D in the following 12 categories: -

1. Shortage, package shipment

2. Shortage, bulk shipment

3. All damage not otherwise provided for

4. Defective or unfit equipment

5. Temperature failures - - 6. Delay

7. Robbery, theft, pilferage - 8. Concealed damage

9. Train accident

10. Fire, marine, and catastrophies

11, Error of employee

12. Vandalism

Unfortunately, the above 12 categories do not indicate the L&D due to

shock and vibration (i.e., rough handling) which is germane to this

work. Freight damage resulting from excessive shock and vibration

would probably be listed in category 3, "all damage not otherwise

provided for" and category 8, "concealed damage." Almost $156.7

million or 51.5 percent of the total 1978 freight loss and damage

payments was classified as category 3, and $1.6 million or 0.5 percent

was classified as category 8. Other major factors that effect L&D

in categories 3 and 8 are inadequate packaging, improper loading, and

claims incorrectly assigned to these categories. The methodology is

concerned with allocating the AAR category 3 and 8 L&D to shock and

vibration in the transport cycle. This allocation is done in four

steps:

5
• step 1: Allocation to shock and vibration versus others

• Step 2: Allocation to linehaul versus yard

• Step 3: Allocation to flat vs. hump yard

Step 4: Allocation to hump yard over speed impact levels.

The details of the methodology are presented in Ref . 2; herein, we present only a summary.

• Step 1: Data from a corrogated container study (Ref. 3) and

from a Whirlpool appliance study (Ref. 4) is combined with a table of

gross claims paid by cause and commodity (Ref. 5) to estimate the allocation of L&D to shock and vibration versus "others."

• Step 2: Data obtained from the Southern Pacific Transportation

Company on shifted loads is used to estimate the allocation of L&D between the linehaul and yards.

• Step 3: Assuming that damage is proportional to the squared

difference between 4 mph and coupling speed (Ref. 6), data on coupling speeds in hump and flat yards (Ref. 7) is combined with the relative switching activity in hump and flat yards (Ref. 8) to estimate the

allocation of L&D between hump and flat yards.

• Step 4: If we assume the frequency distribution of coupling

impacts in hump yards (Ref. 7), can be interpreted as a probability of

occurrence then an equation for the "expected" L&D per coupling impact

can be written in terms of "expected" L&D occurring at various coupling

speeds. The "unknowns" in this equation are the expected L&D occurring

at various coupling speeds. However, if we assume that L&D at one coupling speed is related to the L&D at another coupling speed by the

squared difference in coupling speeds, then a set of simultaneous equations can be generated to allow all the "unknowns" to be solved. This

process is used to estimate the L&D in a hump yard for various levels

of impact.

CONCLUDING REMARKS ,

The details of the analysis and procedures are presented in Ref. 2

In addition, Ref. 2 presents parametric curves which allows one to perform the allocation of L&D based on different assumptions. Also, in

Ref. 2 the methodology is applied to estimating the allocation of

coupler replacements costs due to shock and vibration to various elements of the transport cycle. Finally, an extensive bibliography on

loss and damage is presented in Ref. 2.

6
ACKNOWLEDGEMENTS

This research was supported by the Federal Railroad Administration

(FRA) under contract No. DOT-FR-9082; the project technical monitor

was Ms. Claire Orth. The author wishes to acknowledge the support and

encouragement of Mr. Phil Olekszyk (FRA) and Mr. William Cracker (FRA).

Valuable information to the project was supplied by Mr. Barney

Gallacher (retired, Southern Pacific Transportation Company) and Mr.

Robert Robbins (Weyerhauser Company)

.

REFERENCES

1. "Freight Loss and Damage, 1978," Circular No. FCDP-133, Association

of American Railroads, Freight Claim and Damage, Chicago, Illinois

(April 12,' 1979)

.

2. P. J. Wong, "Allocating Loss and Damage to the Railroad Transport

Cycle."

3. F. E. Ostrem and W. D. Godshall, "An Assessment of the Common

Carrier Shipping Environment, " Forrest Products Laboratory Report

FPL 22 (1979).

4. "Report on Survey of Whirlpool Corporation by Task Force for Prevention of Damage to Household Appliances," Freight Loss and damage Prevention Section, Association of American Railroads, 1970.

5. Braddock, Dunn, and McDonald, "An Economic Model of Cargo Loss:

a Method for Evaluating Cargo Loss Reduction Programs," prepared

for DOT, Report PB-210-223, May, 1972.

6. L. C. Simmons and R. H. Shackson, "Shock and Vibration of Railroad

Movement of Freight," paper presented at the American Society of

Mechanical Engineers Winter Annual Meeting, New York, New York,

November 29 - December 4, 1964, Paper No. 64-WA/RR-7.

7. "National Careful Car Handling Observation Day Results," Association of American Railroads, October , 1969 and 1970.

8. S. J. Petracek et al., "Railroad Classification Yard Technology:

A Survey and Assessment," SRI International, Menlo Park, California, prepared for Tsansportation Systems Center, Cambridge,

Massachusetts, 02142, Report No. FRA/ORD-7 6/304 (July, 1976).

7
EXPORT PACKING IN THE MARINE ENVIRONMENT

J. P. Colletti

John P. Colletti & Associates

Pittsburgh, Pennsylvania 15243

Purpose and Scope

Before there can be any meaningful discussion about

preparation of goods for export shipment, there must first

be a firm understanding of the terms preservation, packaging

and packing. These three terms comprise a total system

which when properly implemented serve as follows:

To protect cargo from the elements and the normal rigors

encountered in export transportation.

To facilitate handling.

To provide a degree of rigidity to the cargo being

shipped.

To provide continued protection to the cargo in short

term or long term storage.

This paper is intended to offer the shipper a ready reference on how to prepare his product for export shipment.

Th^ paper addresses, in general, the basics of preservation,

packaging and packing including the selection of materials,

methods of construction of skids, crates and boxes and a brief look at containerization

Definitions

Preservation is the operation by which goods are protected from the elements, i.e. humidity, fresh water, salt

water, heat, cold and corrosive atmospheres. Preservation

usually consists of the direct application of a coating

specifically designed for protection against a known hazard

such as rust. Other types of preservation are VCI and VPI

which are not contact preservatives, but, rather, additives

in the form of powder or chemically treated paper that serve

to inhibit the formation of water vapor and rust resulting

from that water vapor. Desiccants are also a means of preservation.

Packaging is an operation consisting of wrapping or boxing an item as a preparatory step prior to the final (outer)

shipping container. The type and extent of packaging depends on marketing requirements, segregation requirements,

known or assumed levels of transportation shock and vibration, and is usually performed as an intermediate step in

8
the protection of the item from the effects of transportation ,Packing is the final step in the preparation of goods

for shipment. Packing consists of the outer or external

shipping container, be it a box or crate, and includes such

measures as cushioning, blocking, bracing or anchoring the

item within this outer shipping container. If the shipper

will conscientiously evaluate his cargo and develop the system of preservation, packaging and packing against known or

assumed transportation hazards, his cargo will stand an infinitely better chance of arriving at its destination in

sound condition.

VCI/VPI are vapor corrosion inhibitors or vapor phase

inhibitors which when incorporated in waterproof packaging

can add a substantial measure of protection against moisture .Desiccants are usually moisture absorbing powders contained in packages such as boxes or cloth bags. When placed

in relatively watertight or waterproof voids, these desiccants will absorb excess moisture. They can not, however,

be expected to continue to absorb water or moisture beyond

their absorbtion capability and, therefore, the amount of

desiccant used must be carefully determined considering the

expected temperature/humidity levels and the volume of the

spaces which they are to protect.

Marks and numbers are extremely important. The outer or

external shipping container must clearly show certain critical information essential to the safe handling and expeditious delivery of cargoes to their final destination. The

name and full address of the consignee; an identifying number or code relating to the particular item being shipped;

the full dimensions and gross and net weight in both metric

and British systems; and the appropriate international

shipping symbols such as "Keep Dry", "Fragile", "This Side

Up" and "Lift Here" or "Sling Here", are all part of the

labeling requirements.

Unitization is the assembly of cargoes of similar size

and configuration into a single bundle, group, platform or

pallet. The purpose of unitization is to reduce cubage,

facilitate handling, and usually can provide a greater

degree of rigidity to the unitized cargoes. The bundling of

pipe, coiled wire, lumber and structural steel members are

examples of unitization.

Pal letization is a special case of unitization and consists of placing one or more similar units of cargo on wooden pallets and securing the cargoes to the pallets (usually)

by means of steel or synthetic fabric tension bands. If

9
required, overwraps may be applied to the palletized units

to provide either watershed or waterproof protection. Other

common methods of restraining and securing palletized cargoes are shrink wrap and tension wrap (polyethylene or polypropylene films)

Protective materials generally refers to contact preservatives such as paint, grease and oil or to the watershed/

waterproof liners and wraps applied to protect the cargo

from the elements. "Protective Materials" can also refer to

cushioning materials and blocking and bracing.

Skids are wooden timbers or alternative materials used

either as a base to facilitate handling for heavy cargoes

where cargoes possess inherent rigidity; or serve alone as

a base for cargoes lacking inherent rigidity protecting them

and facilitating handling. Skids are also major structural

members in crate construction. It is important to note that

if skids are used alone as a base to carry a cargo with or

without inherent rigidity, attention must be given to the

type of load, i.e. uniform for concentrated, and the skid

must be designed accordingly. In addition, it is important

to remember for economic reasons, that skids used as structural members in true crates can be significantly smaller in

cross-section than the skids used as supporting bases because crate side and top panels contribute a significant

portion of the overall strength to the crate.

A wood crate is a structural framework of members fastened together to form a rigid enclosure which will protect

the contents during shipping and storage. This enclosure is

usually of rectangular outline and may or may not be sheathed, A crate differs from a nailed wood box in that the

frame work of members in the sides and ends provides the

basic strength, whereas a box must rely for its strength

solely on the boards of the sides, ends, top and bottom.

Crate framework can be considered to be similar to a type

of truss used in bridge construction. It is designed to

absorb most of the stresses imposed by handling and stacking , A wooden box is simply a rectangular enclosure consisting of wooden boards or planks nailed along their ends or

sides to adjacent boards or planks. Boxes generally do not

employ a framework such as that used in crates. However,

boxes can and should employ cleats and battens, wooden

stiffening members, which act as nailers and stiffening members .The wood species most commonly used in crate construction are divided into four (4) groups, largely on the basis

of density. In general, it is good practice to use species

in the same group for similar parts. Group I consists of

10
the softer woods such as pine, spruce and chestnut. Group

II consists of heavier woods such as Douglas fir and southern yellow pine. Group III woods are generally hard woods

of medium density and generally possess relatively good

nail-holding capacity. Examples of these woods are ash,

soft elm and soft maple. Group IV woods are heavy hardwood

species, the heaviest and hardest domestic woods. They have

the greatest capacity to both resist shock and hold nails.

They are difficult to nail and tend to split when nailed,

but are especially useful where high nail holding capacity

is required. Oaks, hickory, birch and white ash are examples of Group IV wood.

Wood defects should be carefully considered when selecting wood for skid, crate and box construction. Generally

speaking, seasoned wood is preferable to green lumber.

Knots and other obvious visible defects such as slope of

grain, decay, wane, shakes, checks, splits, and warping are

usually obvious physical defects which affect the strength

and long-term serviceability of wood. Guidelines for selecting wood with defects are contained in great detail in the

Wood Handbook and the Wood Crate Design Manual (Agriculture

Handbook No. 252)

,

Rub strips or runners are lumber strips secured to the

underside of skids and skid-based crates to facilitate

handling. Rub strips are an essential part of skid assemblies, crates and in box construction for loads in excess

of 200 pounds.

Tension bands are metal or fabric bands or straps used

to secure or bind cargoes to pallets or skid bases or as an

added measure of binding the external members of crates

and boxes. Tension bands come in different dimensions and

are applied by means of mechanical or hydraulic tensioning

equipment. Tension bands are also an essential part of

good packing.

Reinforcing straps are mild steel metal bands fitted

with nail holes which are affixed at the corners of crates

and at the junction of side panel vertical members and top

panel horizontal members. Reinforcing straps should be

applied in two (2) directions where possible. They serve

as an added measure of preventing separation of joints.

Headers are timbers or alternative materials which are

bolted across the ends of skid assemblies. They are generally to be of at least the same cross-section as the skid

members they join. Headers are an essential part of skid

assemblies both in skids acting alone as well as in skids

as part of a crate structure.

n
Load bearing floorboards are wooden timbers or alternative materials which are fastened transversely across the

tops of skid assemblies and carry the load of the item for

which the skid assembly is intended.

Splicing refers to the joining, end to end, of two (2)

lengths of timbers of similar cross section in order to

make one longer section with approximately the same longitudinal strength as a single continuous piece. The ends to

be spliced are to be notched to one half the timber thickness, and through bolts are to be placed vertically through

the joining notched sections. Lapped along each side of the

splice is to be a k" steel plate of length no less than

three (3) times the thickness of the members joined and

through-bolted, side to side, with at least two (2) bolts in

each half of the splice,

A uniform load refers to a load that is distributed more

or less evenly over the entire unsupported length of the

member on which it rests. As was pointed out above, consideration must be given to the type of load, i.e. uniform

or concentrated, when determining the size of members to be

used as skids and load bearing floorboards.

A concentrated load is a load which is not distributed

evenly over the unsupported length of the member on which

it rests. Rather, it is centered over a shorter segment of

the member on which it rests resulting in a higher bending

mortient than a uniform load of similar magnitude.

Rigidity refers to a strength-property of materials

which allows them to resist deformation such as longitudinal

bending or racking. For example, a 20" diameter pipe with

^" wall thickness and length of 20' may be able to be picked up by a sling at its mid-length without any noticeable

deformation while a 2" diameter pipe with wall thickness of

3/16" and length of 20' would droop noticeably if lifted

with a sling at its mid-length. Items with no inherent

rigidity, which are intended for export shipment, should be

skidded or crated in order to facilitate handling and prevent damage.

Fragility is a term used to describe the degree of susceptibility to damage from the normal rigors of transportation, i.e. shock and vibration.

Bending moment , as used within the scope of this paper,

refers to the product of a load acting over a distance to

produce deformation of a structural member which is subjected to the load at some point along its length. The

load may be uniform or concentrated as described above. As

an example, consider a beam supported only at its extreme

ends and subjected to a load at its mid-length such that the

12
resultant of the load acting downward and the reaction faces at the extreme ends acting upward result in a sagging

of the beam. What actually happens here is that the fibers

of the beam in contact with the load are in compression

while the fibers on the underside of the beam opposite the

load are in tension. The bending moments described above

can be written in the form of the following mathematical

expression: BM = (W x L) 7 4 (Foot . Pounds) , where W

is the applied load, L is the unsupported length of the

beam and the denominator 4 takes into account that W is a

concentrated load. Similarly, the mathematical expression

for the bending moment resulting from the application of a uniformly distributed load on the same beam is as follows:

BM = (W X L) 78 (Foot . Pounds) , where the denominator 8

accounts for the fact that W is a uniform load. In some

calculations to determine bending moments on beams where

the applied loads are neither strictly uniform nor strictly

concentrated, it is convenient to use the denominator 6.

Stress is directly related to the bending moment. Math

ematically, Stress = BM -f SM.

The term Section Modulus denotes a property of a partic

ular beam cross-section. It is defined as the moment of

inertia divided by the distance of the most remote fiber

from the neutral axis, and is denoted by the symbol S or

SM, A simple mathematical expression for section modulus

is (b x d2) 7 6 where b is the width of the cross-section

and d is the depth of the cross-section. It is clearly

seen that Section Modulus is extremely helpful in determining the actual stress to which a beam is subjected under

a known Bending Moment.

In this paper, the term "engineered" means that an

analysis must be made of the types of loads and their magnitudes on the various structural members of crates, in

order that their required dimensions may be correctly deter

mined by calculation.

Marks and Numbers

The purpose of Marks and Numbers is to identify the

shipper and consignee, to aid in safe handling, to provide

general information and to identify hazardous materials.

Never identify the contents unless it happens to be hazardous materials.

Marks and Numbers should be made in large (2" minimum

height), block letters and numbers. All numbers such as

gross and net weight and dimensions should be in both

British and metric units, Marks and Numbers should be

placed on three (3) sides of boxes and crates to insure

that they can be seen, and these should be accompanied by

the international symisols such as the umbrella denoting

13
"Keep Dry", the wine glass denoting "Fragile", and the link

chain denoting "Sling Here". Marks and Numbers should be

in indelible ink or paint which contrasts with the background . Preservation

Some items, by their method of manufacture, are already preserved. Others require protective coatings such

as oils, grease, paint or some other contact preservative

which may be specified by manufacturing, engineering,

quality control, or customer requirements. Some items, in

addition to contact preservatives, require wrapping in wax

paper or some other protective film.

In addition to contact preservatives, certain items may

require additional protection from the elements, especially

water, such as shrouds, liners and linings, wraps, VPI or

VCI (moisture inhibitors) or desiccant materials. Wraps

applied over a contact preservative must be grease proof

and require a means of assuring that they remain in place

during handling and transportation. Liners and lining are

waterproof barrier materials applied between framing and

sheathing to provide watershed and diversion capabilities

for the items crated. When shrouds are applied, all projections in sharp corners must be cushioned to prevent pene

tration or abrasion of the shroud from either internal or

external sources. The bottom edges of all shrouds should

be fastened down with batten boards and additional restraints provided to prevent ballooning or flapping of the

shrouds in transit. Adequate bottom ventilation must be

provided either by spacing floorboards (3/8" minimum) or by

drilling one 1" diameter hole for each 5 cubic feet of

shrouded volume. When VPI/VCI materials are used, a suffic

ient quantity of treated paper must be used to completely

enclose the item.

For general watershed and diversion protection, polyethylene films (4 mils minimum thickness) , asphalt laminated kraft paper, filament reinforced polyethylene or poly

ethylene coated kraft paper may be used. When applying

water vapor resistant liners or lining, such as asphalt

laminated kraft paper or polyethylene films (6 mils minimum

thickness) , it is essential that they be sealed tight.

Whenever VPI/VCI treated papers are used, they must be inserted within a tight enclosure, and the liner or lining

must be sealed with waterproof tape. This is also true of

desiccants.

14
Skids, Crates and Boxes

The materials used for skids must be Group IV (hard)

woods such as Beech, Birch, Hard Maple, Hickory, Oak, Rock

Elm, and White Ash. These woods have the greatest nailholding power and the highest overall strength and resistance to shock. However, they are very susceptible to

splitting. These woods should be used for skids, headers,

load bearing floorboards and critical joists.

Group II and III are generally acceptible for exterior

box and crate construction. Group II woods include Douglas

Fir, Hemlock, Southern Yellow Pine, Tamarack and Western

Larch. These woods are harder soft woods. They possess

greater nail-holding power, greater strength and greater

shock resisting capacity than Group I woods. They are more

inclined to split and their grains often deflect nails.

Examples of Group III woods are Ash (except white) Cherry,

Soft Elm, Soft Maple, Sweet Gum, Sycamore and Tupello.

These woods are similar to Group II in nail-holding power

and beam strength but have less tendency to split and

shatter under impact.

When using plywood as sheathing or floorboard material,

type C-D interior plywood with exterior glue is the best

economical selection.

Lumber Selection and Defects

A great deal of consideration must be given to a standard of quality of the wood selected for skids, crates and

boxes. Often the cheapest grade of lumber will contain a large number of defects which are undesirable. Therefore,

it may be necessary to select a higher grade of lumber to

eliminate the majority of disqualifying defects. Generally

knots are not to exceed k of the width of the member. No

knot, regardless of size, will be permitted on the edge of

any member. Obviously, this is because the member may be

subjected to bending and a knot may fall in an area subjected to compression or tension. Cross grain or slope of

grain, disregarding slight local deviations, along the

general direction of the grain as related to the longitudinal axis of the wood member, should not be steeper

than 1" in 15" of length. Wane is either bark or lack of

wood on the edge or corner of a piece of lumber. Generally

wane is permitted on one edge only, but should not exceed

1/6 of the width, thickness, or 1/3 of the length of the

member. Checks and splits, lengthwise openings from

separations during seasoning, may reduce wood's resistance

to shear. Checks and splits which extend through the entire thickness of the piece are not permitted. Shake is a separation along the grain, largely between the growth

15
rings, which occur while the wood is seasoning. Shakes in

members subjected to bending reduce the resistance to shear

and therefore, should be closely limited in structural members. Decay, a disintegration of wood, results from the

action of wood-destroying fungi. It seriously affects the

strength properties of wood and its resistance to nail withdrawal. However, if it is determined that the total amount

of decay beneath the surface does not extend beyond the surface outline, the dimensional limitations for knots apply.

Warp along the longitudinal axis of the lumber should not

be more than l"':in 8" of length. Warp, widthwise, should

not be more than one-eighth inch in 4" of width. The

acceptable range of moisture content in lumber used for

skids, crates and boxes should lie between 12% and 19%.

No opportunity should be overlooked to utilize materials

besides wood or plywood for crate, box or skid construction

where practically and economically feasible. Steel alternatives for wood skid members may be the simplist substitution. For example, a 4" x 4" timber may be replaced by a 3" X 4.1 lb. steel channel iron or by a 3"x 5.7 lb. I-beam

or by a 3 " X 3 " X V' angle iron. Wherever material substitutions are contemplated for heavy loads, they should be

engineered for the specific purpose intended.

Design

A proper analysis of forces to which skids, crates and

boxes may be subjected must include consideration of compression, lateral thrust, impacts, repeated handlings,

abiise, tension and inertial forces on the structure and

the cargo. In this regard, it must be remembered that

inertial loadings encountered aboard ship often exceed

those encountered in the other modes of transportation.

Basic Design Criteria

Skids must be of Group IV woods and engineered for uniform or concentrated loads. Headers are to be bolted using

washers and double nuts or upset threads. Skids are to be

spaced not more than 48" apart and are to be of single piece

construction or, if over 12' long, spliced according to an

approved method. The ends of skids are to be chamfered and

are to rest on chamfered rub strips. Cargo is to be bolted

or tension banded to skids using engineering design methods

for determining the sizes of bolts and tension bands. For

very heavy loads, consideration must be given to the crushing strength of the wood or alternative material. Load

bearing floorboards can be analyzed as beams using the formulas for bending moment to determine the required section

modulus. The allowable stress used in the formula for

16
section modulus can be taken as 1,000 psi. For hard woods,

this allowable stress provides an adequate factor of safety.

Where the distance between skids might exceed 48", it will

be necessary to add an additional skid. The bending moment

on the load bearing floorboards, then, should still be calculated on the basis of the length between outside skids.

Example ; A 15,000 lb. load is to be supported on skids

whose length has been determined to be 15'.

Calculate the required timber size.

Using the formula BM = (W x L) 76, the bending moment

will be 37,500 Foot • Pounds. Calculating the required

section modulus = BM -f allowable stress = 450 cubic inches.

Remember to multiply the bending moment by 12 in order to

convert Foot- Pounds to Inch . Pounds. Since section modulus = (b x d^) 7 6jyou can solve by trial and error by substituting cross sectional dimensions as follows: Try a 10" X 10" timber. This yields a section modulus of 166.7

cubic inches. Two (2) skids of these cross sectional dimensions yield of total of 333.4 cubic inches. It is obvious, then, that two (2) 10" x 10" timbers do not provide

the required section modulus (450 cubic inches) for a quasi

uniform load. The next logical choice would be two (2)

12" X 12" timbers. Note, however, that if the load is truly

uniform (BM = W x L -f 8) , the required section modulus is

only 337.5 cubic inches. The two (2) 10" x 10" timbers then

come very close to making the required section modulus, and

with the factor of safety provided by using the allowable

stress of 1,000 psi, the two (2) 10" x 10" timbers would

serve satisfactorily for a strictly uniform load. For most

hard woods, the allowable stress of 1,000 psi provides a comfortable factor of safety of approximately 1.5. In calculating the basic stresses for structural lumber, impact

loading is generally ignored, but long-time loading and a safety factor are considered. A piece of wood will carry

less load for a long time than it will for a short time.

Consideration should be given to the expected interval of

storage, i.e. short time verses long time. In addition,

if research or historical data indicate that a particular

port of loading and/or a particular port of discharge have

a higher frequency of cargo claims due to rough handling,

timber sizes may be increased by applying an appropriate

factor of safety or by requiring that the actual timber size

will be one full unit larger than derived by calculation.

Remember that rub strips must be applied to the skids. An

added precaution against the accidental loss of a rub strip

is the use of reinforcing straps from the rub strip to the

underside of the skid members.

17
Crates

In general. Group II and III woods are to be used in

crate construction except for skids, headers and occasionally load bearing floorboards which should be Group IV

woods. All nails used are to be cemented coated. Barbed,

screw, or serrated nails are occasionally used, but for

practicality and economy, cement coated nails make the best

selection

All skid members in crate construction generally follow

the same construction requirements as skid members used as

skids alone. However, skid members sizes in crates can be

substantially smaller in cross sectional area because, in

crate design, it is assumed that a large part of the load

imposed by the contents is carried by the side panels acting as trusses. Therefore, large skids are not necessary

as load-carrying members because the sides act integrally

with the skids in this function. While this assumption

results in smaller size skids, it does not permit handling

and moving a loaded base alone without the sides and ends

fastened in place.

Crates may be either open or closed (sheathed) . It is

not always necessary to sheathe a crate if the contents do

not require a degree of protection from the elements.

Opened crates require less lumber and, therefore, if properly designed, can be less expensive to fabricate. This

may not always be true, and, to achieve greater economy,

it is necessary to make an engineering economy analysis

to determine whether an open crate or a sheathed crate is

more economical in terms of labor and cost of materials.

This paper will discuss the design and construction of open

crates since the contents impose loadings on structural

members which must be determined either by graphical analysis or engineering methods of resolving forces. The sides

and ends, as well as some members of the base, are considered as part of a bridge truss. The size of members are

determined by analyzing this truss. The Howe truss, with

its parallel upper and lower chord and its vertical and

diagonal members, has the same general pattern as the frame

members of the side of a wooden crate. Since the truss is

a framed structure composed of straight members, the

stresses in the members due to loads must be either compression or tension. The magnitude and character of the

stress in each member can be determined. The required size

of all tension members in the truss is determined by the

formula A = P t f ; where A is the required cross sectional

area of the member in square inches, P = the total load in

pounds (as determined from the resolution of forces or from

graphical analysis) , and f is the working stress in pounds

18
per square inch (in tension parallel to the grain) . With

support at each end, the major stresses in strut and lower

frame members are tension stresses and those in the diagonals and upper frame members are compression stresses.

Compression members must be designed as columns and

column formulas must be used to determine their sizes. In

crate design, there are essentially three column formulas.

The selection of the proper formula depends on the unsupported length of the column and, columns are therefore

classified as short, intermediate and long. It is beyond

the scope of this paper to discuss the various factors and

the application of these in the appropriate column formulas.

The Wood Crate Design Manual (Agriculture Handbook No. 252)

is an excellent reference text for the more determined

crate builder. It must be remembered that it is most

probable that crates of similar dimensions will be stacked,

one upon the other, aboard ship or in storage. If crates

are of exactly the same overall dimensions, the corner posts

will carry the superimposed loads as columns. These anticipated superimposed loads must be included in the strength

analyses. If superimposed loads consists of smaller crates

or other types of loads that do not rest upon the corner

posts, the structural members of the top panels will be subjected to bending as well as to compressive loadings resulting from handling especially with slings or chains. Therefore, these structural members must be analyzed as beams

subjected to bending and axial compression. If highly concentrated loads (in the center 1/3 of the crate) are to be

crated, the skid depth must be increased. This, however,

will be apparent if the side panels are properly analyzed.

Crates should not be higher than they are wide. Side

panels are to be divided by a suitable number of vertical

members so that diagonals are as close to a 45° degree angle

as possible. Top and bottom horizontal and vertical members

are to be through members (extend to full extent of length

and height dimensions) . All end panels are to have one or

more diagonals. Avoid splicing members less than 16' long.

Splicing, where required, must be accomplished using an

approved method. Intersections of diagonals are to be reinforced using plywood gussets or lumber bridge.

If the crate height exceeds 72", a through intermediate

horizontal member is required at mid-height of the crate.

Side panel width (i.e. between vertical members) must not

exceed 42". The geometry of the panels must be altered to

add an additional panel so that panel widths do not exceed

42". Lower horizontal members are to rest on the ends of the

floorboards with notches cut in headers and load bearing

19
floorboards to accept the lower horizontal members. Vertical and diagonal members must be in the same plane and to

the outside of the horizontal members. Side panel diagonals

should slope from the top of a vertical member down to the

skid base.

End panel design should not exceed 42" in width. End

panels for crates having a skid width in excess of 42" will

require intermediate vertical members. End panels for

crates having more than two (2) skids will require a vertical member above each skid. Filler strips will be required

to allow end panel vertical members to rest across the ends

of skids. The filler strips will fill the void between the

headers and the lower horizontal members.

Top panels are critical since most members will be in

compression under the influence of various types of materials handling equipment and superimposed loadings. Top

panel lateral and diagonal members will be in the same

plane and rest upon the longitudinals and extend to their

edges.

Where protection from the elements is essential or to

meet customer requirements, a sheathed-crate , either 3/4"

lumber or V' plywood (C-D, exterior glue) sheathing can be

used. Reinforcement strapping is required on all corners

and at all intermediate, horizontal and vertical member

junctures after the crate is assembled. ,.. r Where crate items require additional protection from

the elements, as discussed earlier in this paper, appropriate steps must be taken in the early stages of crate

construction to apply the required crate liner between

internal framing and external sheathing. If the crate is

not to be watertight, sufficient ventilation must be provided. If the contents are to be provided with waterproof protection, the item must be properly and totally

wrapped with either asphalt laminated kraft paper or

polyethylene film and sealed with waterproof tape in

addition to the crate liner material.

The strength and rigidity of crates are highly dependent on the fastenings. Nails, lag screws, bolts,

screws and metal connectors are the most important

fastenings in crate construction. This paper will cover

briefly nails and nailing rules. Refer to "Nailing Better

Wood Boxes and Crates "by L. 0, Anderson, Agriculture Handbook No, 160, for a more complete discussion of nails and

nailing rules. Cement coated nails are being more widely

used today than ever before, primarily, because many crate

builders use automatic nailing equipment which lend themselves more readily to the use of belted cement coated

nails. Nails should be driven through the thinner member

20
into the thicker member where possible and should penetrate both members leaving a minimum of k" for clinching.

Clinching is one of the best methods of increasing effectiveness of nails. It is used almost entirely in the fabrication of crate panels, except when frame members or other

crate parts are greater than 2" thick. Clinched nails have

50 to 150 percent greater withdrawal resistance than unclinched nails when driven into drywood, Pre-drilling the

wood before the nails are driven may be necessary to prevent splitting in very dense woods or with nails of large

diameter. Nails should not be over driven. They should

positioned no less than the thickness of the piece from the

end or half the thickness of the piece from the side edge.

When members, both of which have 3" or greater thickness

are joined together, bolts are to be used. Nails should be

staggered to prevent any two nails from entering the same

grain line of any board. Follow approved nailing techniques

as outlined in the handbook described above.

Where practical, the use of tension bands will provide

an added degree of a reinforcement to the crate assembly.

Tension bands should be tight enough to cause a light

crushing of the ends of the main structural over which they

pass. Tension bands should be stapled to prevent their

movement during transportation and handling.

A crate can be assembled before or after loading the

item on the skid base, whichever is appropriate, but internal blocking and bracing of the item in the crate must

be done at the time the item is set on the skid base. The

blocking and bracing must be of substantial design and construction to prevent the free movement of the item within

the crate due to the forces encountered in transportation

and handling. Blocking and bracing are not to be taken

lightly. The inertial loading on the crate and its content

aboard ship often exceeds twice that encountered in the

other modes of transportation.

Boxes

Boxes are not to be used for loads in excess of 5,000

lbs. or lengths in excess of 16'. Group II and III woods

are to be used. All nails are to be cement coated. Boxes

which exceed 200 pounds gross weight will require 2" x 4"

rub strips. When any unsupported span of top, end or side

lumber exceeds 36", additional interior battens or cleats

will be required. Cleated plywood boxes for loads over

1,000 pounds must have load bearing bases with properly

size skids, headers and rub strips and are to be nailed in

accordance with the preceeding nailing rules. All boxes

require tension bands sized according to the load and

arranged in two directions passing over cleats or battens.

21
Bands should be stapled to prevent movement and should be

tight enough to cause light crushing of the corners of the

members over which they pass. If a boxed item is of large

mass (weight) , appropriate filler or cushioning materials

filling the voids around the item may not be effective.

Therefore, dunnage or blocking and bracing, where practical,

should be used. Where the item boxed requires protection

from the elements, the internal surfaces of the box may be

lined as described under crates and the item itself should

be properly preserved.

Unitization and Palletization

Unitization provides a more economic package than individually shipped pieces. It also provides ease of handling and storage and provides a greater degree of protection than individual units. Pipe and conduit are easily

bundled. They mtay require special plastic end protectors

to protect internal or external threads. The ends of bundled pipe can be boxed or completely covered with double

or triple wall fiberboard secured with tension bands. In

addition, long bundles may be bucked. Bucks are wooden

frames which surround the girth of the bundle. They are to

be nailed at the right angle junctures and tension banded.

Tension bands are to be stapled to prevent accidental loss

of the bands. Bucks should be located at five foot intervals maximum.

Lumber and paneling are usually bundled. Care must be

taken to avoid over-tensioning bands which will mar their

edges. Paneling should be covered with water-resistant

paper or polyethylene film.

Coiled wire can be bundled. Because of the historical

poor bundling methods used for wire, substantial losses

have occurred. Consignees frequently use coiled wire to

make nails, screws and bolts. Kinked or crooked wire will

interfere with the extrusion process and substantial claims

may arise.

Lumber and paneling can also be bundled. Care must be taken to insure that tension bands do not damage the items bundled. Coiled wire can be bundled. The usual problem

encountered here is when tension bands or wrapping wires

come off allowing the coils to become disarranged or

crushed. The consignee usually has a specific machine set

up for manufacturing items such as bolts, screws and rods.

Hence, damage to the coils can result in a claim.

Palletization is best for similar size fiberboard cartons, drums, and coiled sheet steel. Do not overload or

stack the items to high. Overloaded pallets break. Too

high of a stow can result in crushing of the cartons in the

lower levels. Then further damage occurs when the other22
wise neat stacking falls apart. In-transit handling of

broken down pallets usually results in further abuse.

Fabric or steel banding is usually one of the best methods

of securing an entire unit load. It may be advisable to

employ vertical and horizontal corner protectors to eliminate banding damage. Shrink wrapping provides a high

strength securement to a palletized load. It can also be

applied to protect against contact with water.

Palletized drums must be fitted with partially-framed

top to allow for safe utilization of tension bands.

Tensioning of the bands must not cause damage to the pallet

load bearing boards or to the cargo. Fiberboard sheets

across the top and partially down the sides of drums will

serve to keep the tension bands positioned and provide a

' level surface for stacking other pallets.

In general, old or badly worn pallets should not be

used. Pallets can be repaired. Some companies use secondary re-usable pallets with good success. Still, old wood

and loose nails can result in broken pallets which invite

further abuse in handling.

Container Problems

Containers are subject to the same shock and vibration

forces as over-the-road trailers and railroad cars. In

addition, very high inertial loadings are experienced by

the contents due to the pitching, rolling, heaving and

surging of a ship at sea.

The major causes of damage to containerized cargoes

are improper stowage, inadequate dunnage, lack of securing,

overloading and poor weight distribution. Any assumption

that the container is a substitute for safe stowage and

handling is an invitation to disaster, A good rule to

adopt is, "Stow and Secure for the Worst Conditions".

Containers may travel to seaport by railroad. Constant vibration and occasional sharp humping forces must

be taken into consideration. When loading a container

for sea transport, always consider the six basic ship

motions; yaw, heave, sway, pitch, roll and surge. Occasionally heavy seas will have a pronounced effect on cargoes in containers.

Blocking and bracing is essential to the safety of the

cargo. Materials commonly used for securement are lumber,

plywood, strapping, fiberboard and inflatables. Lumber

can be used as a filler, for decking, blocking and bracing

and constructing partitions. Plywood can be used as a partition, divider and auxiliary decking. Heavy duty

strapping can be used to separate cargo and to tie down

heavy and akward items. The strapping must be firmly

anchored and properly tensioned for the greatest effect-
iveness. Fiberboard is available in sheets, rolls and

structural shapes and can be used for light-duty bracing,

as dividers, decks and partitions. Inflatables are available in paper or rubber and may be re-usable or disposable.

They are expensive and not recommended for voids in excess

of eighteen inches. Inflatables are used for light and

medium duty bracing.

Consideration is another major cause of damage to cargo,.

It is not generally known that fiberboard boxes and crate

or dunnage lumber contribute to the generation of water

vapor in sea containers. Furthermore, in changing temperature and humidity conditions, condensation can form within

containers and drip down from the overhead onto moisturesensitive packaging and cargoes. These conditions can be

remedied, in part, by using seasoned lumber for dunnage and

crate construction. Adequate (pre-packaging) preservation

of moisture-sensitive items can be the best method of protecting against water damage. Overwraps such as canvas

or polyethylene sheeting will serve to divert condensation

which drips from the overhead. It may be necessary with

some types of cargoes to provide completely waterproof

liners or wraps inside of which is VCI/VPI or desiccant

materials. Cargoes are more likely to be subjected to condensation and water damage over a long time internal such

as long transportation distances or long duration storage.

Therefore, it is incumbent upon the shipper to consider

all< these factors when preparing cargo for export.

The annual report of the cargo loss prevention committee

of American Institute of Marine Underwriters contained valuable advice on the use of containers in shipping. Extracts

from the report follow;

Normal reaction is for a shipper to use domestic packaging and consider the container as an additional protection. It is our experience that containers may leak and

the cargo must be protected against moisture and water

damage. Additional emphasis is needed on the use of dunnage and tight packing in containers.

Several offices report that losses have been experienced

due to defective containers. Many shippers don't employ

adequate container inspection procedures. It appears that

some insureds think that because their goods are containerized the packing can be of a minimal nature. Our experience continues to show that such minimally packed goods

are likely to be damaged by rain and/or sea water-when

shipped in poorly maintained containers.

Many shippers continue to use containers as a means of

packaging and claims due to crushing, water damage and improper or inadequate stowage, especially of heavy machinery,

continue to be a problem.

24
Losses have also been experienced where shipments of

high value electronic units have been made in containers.

The units are secured on lumber bases which in turn are

then secured to pallets with the units being entirely

shrouded in polyethylene sheeting which also encompasses

the wooden base to which the units are attached. It was

found that these wooden bases were constructed of green or

improperly dried lumber, which gave off moisture, which became trapped in the polyethylene shrouding. During the

course of transportation fluctuations in temperature caused

this moisture to condense on the exposed metal areas of the

electronic unit, causing serious damage.

We have also observed that machinery which is top heavy

has on occasion been stowed in containers without adequate

bracing and precautions to prevent the machine from tipping

On one occasion a container loaded with tractor engines

arrived at destination with every engine damaged, as a result of their center of gravity being high. Although the

engines were braced along the floor of the container, and

would prevent lateral or fore and aft movement, there was

no bracing up higher and with their relatively high center

of gravity they tipped, coming in contact with one another,

causing damage. Shippers should be cautioned to be aware

of the center of gravity of machinery and other heavy or

odd sized pieces being shipped in containers and adequate

bracing to prevent tipping should be done.

Although containerization of cargo continues to grow

worldwide, the packing of goods into house to house containers by shippers, as well as securing of the goods in

the containers, continues to be a cause for concern. We

find in many instances cargo to be damaged by condensation

within the container and/or by extreme heating or freezing.

Once a container is loaded and the doors securely shut, the

only way in which the outside weather can affect the cargo

is through changes in the temperature.

Unless the internal temperature of the container is

controlled by mechanical or other means, the temperature

of the air inside the container will follow the temperature

of the air outside. Extreme fluctuations in the air temperature can cause condensation to settle on the cargo; if

the container is exposed to very high temperatures, the

cargo within the container may sustain damage or, if the

container is exposed to extremely low temperatures, the

cargo can be damaged, such as change in the chemical state

of some goods (e.g. drugs) making them useless and sometimes

dangerous, or freezing and spoiling of fresh fruit, vegetables, etc., freezing of bottled liquids with subsequent

bursting of bottles.

25
Taking into consideration the anticipated voyage, its

length, temperatures normally expected to be encountered,

consideration should be given to stowing goods which are

susceptible to damage by extreme heat or cold to shipping

them in insulated or refrigerated containers where temperature inside the container can be controlled to some

degree

,

In other cases certain precision machinery or electronic equipment may require the use of VCI, VPI or powder

desiccants. It must be pointed out, however, that in order

for these moisture control measures to take full effect, th'

packaging and packing must be total ly sealed.

Shipping Losses and Insurance

Under normal conditions of domestic rail shipments,

material loaded in open cars is inspected by railroad

representatives before the car is moved and the railroad

assumes responsibility. In closed cars , however , the

Association of American Railroads rules are not mandatory

and are used only for guidance. Closed cars are not

ordinarily inspected, but if damage occurs to the contents,

they are inspected at the destination to determine the

cause before a settlement is made.

Export shipping companies are specifically exempt from

most forms of liabilities under the laws of many countries.

The exceptions to this usually include loss or damage due

to negligence in proper loading, custody, or delivery of

the goods. The shipper or consignee must assume responsibility for all remaining risks during the shipment.

To prevent loss to the shipper, a form of marine insurance covers these losses. Marine insurance may be obtained to cover such perils as pilferage, theft, and leakage, as well as loss or damage if the ship should sink,

burn, or be involved in a collision. However, the more

hazards covered by the policy the higher the rate, so it is

not economical to pay for broader protection than is actually required.

Rates in marine insurance are rather complex and are

not fixed. They depend, among other things, on the type

of vessel, the route, the perils insured against, the type

of packing used, and the loss record of the shipper. This

latter factor, of course, reflects the type of container

and the method of blocking and bracing used by the shipper,

because well-constructed and well-packed crates will

normally receive little damage during the voyage. A shipper who uses adequate containers pays lower rates. Underwriters keep statistical records of shippers they deal with

and allow lower rates for those with good records.

26
Damage and Claims

It has been the writers experience that too frequently

one or more of the three steps in preparation for shipment

are less than adequate and will inevitably result in damage

of one type or another to the cargo. Precision machinery

shipped long distances or subjected to long term storage

without adequate preservation will rust. Electronic equipment shipped without serious consideration being given to

adequate protection from vibration and shock will sustain

physical damage. Items requiring a degree of dimensional

stability (rigidity) will be damaged if the packaging and

packing is not properly engineered and constructed. With

regard to containerization (sea containers) , a tremendous

number of cargo losses occur each year due to ignorance

of the proper use of these containers, specifically the

requirement for adequate blocking and bracing and protection of the cargo against condensation.

A major marine insurance company has made an analysis

of principal causes of losses and found that, in the Handling and Stowage Category, 39% of all losses are due to

container damage including breakage, leakage and crushing.

In the Water Damage Category, 10% of all losses are due to

fresh water, sweat and salt water damage. Nevertheless, it

concludes, 70% of all cargo losses are preventable.

27
INTERNATIONAL SYMBOLS
AGRICULTURE HANDBOOK 2 52, U.S. DEPT. OF AGRICULTURE

OPEN CRATES

THREE-WAY CORNER

NAILING

M-119667

i9ore 42.—Light-duty open crate (loads to 200 pounds) with three-way corner nailin3, the key to proper assembly nailing of crates of this type.

ASSEMBLY

STRAPPING

M-119866

igure 41 . —Limited-military type open crate for loads to 2,500

pounds, designed for the shipment of light, bulky items that do not require a waterproof container.

29
Figure 1.—^Typicat open crate.

M-120691

CARRIAGE BOLT

(PLACE TO CLEAR

EDGE STRUT OF END)

ADD EXTRA SKID

CENTER OF

"BALANCE

-28"

RUBBING STRIP

Figure 51.—Bases for light-duty open crates: A, Through 42

inches wide/ 6, over 42 inches wide.

30
TYPICAL NAILING PATTERNS

-EDGE MEMBER

^STRUTS AND

DIAGONALS

-CROSSING MEMBERS

S

1

7 i5

13

13

OR GREATER

TYPICAL SKID FOR OPEN TYPE CRATE

1/4 BOLT

END HEADERS'' BY 3" OR 4" BY

LOAD-BEARING

MEMBERS

FILLER STRIP

\6

DIAGONAL

THICKNESS OF END SHEATHING

31
AGRICULTURE HANDBOOK 25 2, U.S. DEPT. OF AGRICULTURE

END CROSS MEMBER UPPER EDGE MEMBER Zl

DIAGONAL

DIAGONAL FLOOR MEMBER

SKID

T~fi

v..• 1. J t J

BASE

LOWER EDGE MEMBER

RUBBING STRIP

—mi or END

i

UPPER FRAME MEMBER

1^

DIAGONAL

WIDTHS THROUGH 42

IN TERMEDIA TE MEMBER

SIDE

LOWER FRAME MEMBER

is;

.JOISTS DIAGONAL

5

1

1 1 II

WIDTHS OVER 42'

TOP

32
WOOD CRATE DESIGN MANUAL

TOP TO SIDE

TRIM STRUTS FOR SLING AND FORKLIFT HANDLING

M-l 19719

Figure 58.—Assembly of light-duty open crate.

TOP TO END

TRIM STRUTS FOR SLING AND FORKLIFT HANDLING '

M-1 19702

Figure 59.—Assembly of covered style light-duty open crate

33
AGRICULTURE HANDBOOK 2 52, U.S. DEPT. OF AGRICULTURE

LOAD-BEARING END FLOOR

MEMBER—I MEMBER

(S

UPPER EDGE MEMBER

DIAGONAL

LOWER EDGE MEMBER-^ STRUT

BASE

T-SKID

'RUBBING STRIP

END

UPPER EDGE

STRUT ^DIAGONAlA MEMBER ^LONGITUDINAL MEMBER

LATERAL

MEMBERA

I SI

SIDE LOWER EDGE

MEMBER

TOP

ASSEMBLED

Figure 47.—Style A limited-military type open crate.

34
TYPICAL CORNER REINFORCEMENT

TENSIONED

STRAPS

B

M-l 19682

Figure 1 0.—Strapping for crates: A, Sheathed crate with skid base; 0, additional strap for sill-type base.

35
TYPICAL SHALLOW CRATE

TOP CROSS

MEMBER

BATTEN

^END CLEAT

DIAGONAL

TOP CROSS MEMBERDIAGONALPLYWOOD

re S.—Crate damase caused by a ^rabhook when there was

insufficient joist support in the top of the crate.

36
M-119683 Figure 64.—Rough-handlins tests for crates: A, superimposed

load; B, edgewise drop/ C, comerwise drop; and O, pen- dulum impact.

37
PACKAGING SOFTWARE

FOR SHIPMENT AND STORAGE

B.D. Winn

Southwest Research Institute

P.O. Drawer 28510, Div. 14

San Antonio, TX 78284

W.D. Downing

Southwest Research Institute

P.O. Drawer 28510, Div. 14

San Antonio, TX 78284

S.B. Crumrine

Southwest Research Institute

P.O. Drawer 28510, Div. 14

San Antonio, TX 78284

Abstract: The proliferation in the use of computers in all types of

equipment has led to a dramatic increase in demand for computer

software. Software is distributed on many different media including

paper, magnetic materials and semiconductor memories. Each medium has

its own handling requirements. This paper will discuss packaging,

preservation methods and special considerations involved in preparing

computer software for shipment and storage. Emphasis will be given to

techniques designed to prevent damage to the software due to

temperature, humidity, static discharge, electromagnetic emissions and

other transportation environments.

Key Words: Error correction; error detection; magnetic media; memory;

semiconductor memory; storage media

As computers become more complex and software costs increase

the importance of storing and transporting software without failures

becomes more evident. Failures due to lost data on the various

storage media can be extremely costly. This paper will attempt to

describe the various techniques utilized in preparing software for

shipment and storage. Various storage media will be discussed,

including semiconductor and magnetic media. In addition, methods by

which software is internally prepared to help eliminate errors and

detect and correct them when they occur will be covered.

38
The term "memory" refers to a medium capable of storing

Information and providing access to that Information. Semiconductor

memories are very commonly used In present day computer systems.

These devices are programmed to represent either stored data or a part

of the program to be carried out by the cpu. This Is accomplished by

storing a pattern of bits, or binary digits, at a specified location,

or address In memory. The device Is said to contain one byte of

Information at that address and the contents of that address can be

read at any future time to obtain the same bit pattern that was

originally stored.

Information In a semiconductor memory is specified in terms of

I's and O's. Electrically, this is presented as the presence or lack

of a charge, voltage or current, depending upon the type of device.

Over the past several years the speed and density of these devices

have Increased to a point where a semiconductor memory may contain

more than 64,000 bits on a single chip. Since a single bit error can

cause an incorrect answer or a program halt, it is very Important to

exercise care in the handling of these devices in order to avoid

damage or the loss of data.

Semiconductor memories are subject to two major types of errors. The first type is called a "hard error." This type of error

is the result of permanent damage to the chip. The second type is

called a "soft error." This type of error is the result of temporary

alteration of data without permanent damage to the chip.

Hard errors are commonly caused by exposing the chip to an environment in excess of the limits specified by the manufacturer.

The resultant failures may be mechanical or electrical. The most

common causes of hard errors are excessive temperature and voltage,

either steady-state, transient or cycling. Humidity, vibration and

shock also contribute to device-damaging hard errors.

Soft errors in semiconductor devices have only been recognized

for about three years. They are characterized by random errors which

appear and disappear at several locations. For example, a byte is

found to contain an altered bit pattern. When the memory cell is

tested, it works normally, but the problem reappears at a new address.

Soft errors have become more prevalent in the newer, denser

semiconductor memories. Studies have been made and reveal that soft

errors are caused by ionizing radiation which releases fast moving

charged particles in the chip. It is important to note that in soft

errors, the chip is not permanently damaged, but the information

contained in the device may be altered.

In recognition of the possible causes of failure in

semiconductor memories, most manufacturers exercise great caution in

39
/

packaging these devices. Many follow the guidelines set down in MILM-555565 and subsequent revisions to prepare semiconductor memories

for delivery. The general provisions of MIL-M-555565 are for physical

protection and field force protection of the chip. The following is a discussion of these provisions and several ways in which they may be

Implemented.

Physical protection refers to the design of carriers, wrapping

and cushioning to protect the device against several types of physical

damage, such as vibration, shock, moisture and corrosion. In general,

the specification requires compliance with MIL-P-116 for physical

protection. It is important to note that in providing for physical

protection of the device, care must be taken not to introduce or use

materials which generate an electrostatic charge. The carrier must

also be designed to maintain physical separation of the device leads.

Field force protection refers to the design of wrappings or bags to protect the device against several types of forces. These

include electrostatic forces, electromagnetic forces, magnetic forces

and radiation forces. The specification generally requires the use of

materials conforming to MIL-B-81705 for field force protection. These

materials are intended primarily as protection against static charges.

They have a permanent conductivity on all surfaces to permit a controlled bleed-off of static charges to ground without producing a spark. For protection against other field forces, the specification

recommends overwrapping the devices with additional layers of material

with suitable shielding properties. Aluminum foil wrapping is

recommended for electromagnetic protection, enclosure with ferrous

metals for magnetic protection and enclosure with lead or lead filled

compositions for radiation protection.

Protection against electrostatic forces is the most important

of the four provisions. Static charges generate tremendous amounts of

energy and noise which are primary causes of hard errors. Static

charges may range between 5000 to 10,000 volts. In designing

protective wrappings against electrostatic forces, the designer must

consider: 1) internally generated static charge and 2) external

electrostatic fields.

Several commercially available wrappings or bags are available

which offer protection against internal and external static charges.

Additionally, some manufacturers use anti-static tubular magazines

which offer both physical protection and field force protection.

Generally, the bags and magazines are fabricated from non-static

generating plastics and are surface treated with conductive materials.

40
Protection from ultraviolet light must be provided for certain

types of memories. Erasable and Programmable Read-Only Memories

(EPROM's) are designed to be unprogrammed or erased by exposure to

ultraviolet light. A clear window is provided in the case of the chip

which exposes the semiconductor to the light. Typically, a covering

of some type is applied to the window when it is desired to retain the

contents of an EPROM indefinitely.

The presence of fast moving charged particles in semiconductors

is the cause of many soft failures in new devices. Sources of this

radiation are both internal and external to the device. Alpha

particles are generated by the decaying atoms of uranium, thorium and

other nuclei commonly found in many semiconductors. Another source of

ionizing radiation is cosmic rays found in the earth's atmosphere.

Although the effects of these forms of radiation may be reduced by

shielding, they cannot be eliminated. As memories become higher in

density soft errors will become a bigger problem. This will probably

force the use of error correcting codes in future systems.

Possibly the most commonly used method of storing and

transporting computer software is through the use of magnetic media.

This method is preferred over the other kinds because of its non- volatility, ease of storage, and reliability. Magnetic media consists

mainly of tapes, disks (hard platter and Winchester), and flexible

floppy diskettes. Since this form of media is used so often, methods

have been developed to protect software stored on them. This

protection is both external (physical protection) and internal (error

prevention, detection and correction).

Information is stored in terms of I's and O's on magnetic media

in the form of magnetized particles. The physics involved in reading

and writing the information is the same for both disks and tapes.

Although the information is non-volatile, after extended periods of

time the particles become less distinguishable, requiring some form of

periodic backup procedure. Both tapes and disks continue to gain

popularity in today's market as there is a constant trend to make

storage better by increasing flux and bit density, thereby increasing

storage capability. As will be discussed later, this in itself is one cause of problems in data storage.

The first magnetic media utilized was the magnetic tape. For

larger systems this is an ideal form of storage; however, access time

is very slow. The hard disk was developed to increase access time by

providing true random access to all data on the device. The disks are very sensitive to dust and particles in the air and require an

extremely clean operating and storage environment. This is often hard

to accomplish and leads to high expenses. Disks are removable and

when care is taken are sometimes used for transporting and storing

data.

41
Cleanliness is extremely important when using hard disks. The

disks are placed in containers in a clean room environment, and are packaged in a way which prevents foreign matter from settling on the

disks. They should be shipped in containers lined with polyfoam

material to provide maximum sealing and insure protection of the disks

and the data on them. Recommended shipping and storing conditions are

10° - 85°F to insure data retention. In order to retrieve the data,

however, a temperature range of 60° - 135 "F must be maintained.

In an attempt to provide an alternative disk system with a less

rigid standard for cleanliness, the Winchester type drives were

created. Unlike the normal disk, the Winchester allows contact

between the head and the disk surface. The disk and drives are

contained in their own clean room environment which eliminates the

need for special care and cleanliness in handling. Only recently have

the Winchester systems been designed to be removable, allowing

transportation. Cost, however, restricts serious consideration of

Winchesters as mechanisms for transporting software.

Another alternative to the disk is the floppy diskette. These

diskettes contain significantly less information than regular hard

disks but are considerably more versatile. Diskettes require almost

no special handling during use and are ideal for smaller systems.

They are very widely used for transporting and storing software.

Although diskettes were designed for versatility, care must be

taken with their storage and use. They have built in features to

protect data, including special features to prevent particles from

becoming lodged between the jacket and disk surface. The envelopes

which enclose the diskettes are made of impregnated plastic, which

prevents the accumulation of static electric charges which may cause

loss of data. There is also a soft liner to provide a fluffiness

which helps clean the disks.

In transporting and storing floppy diskettes, care must be

taken to prevent damage to the diskette and loss of data. The exposed

areas of the diskette should always be covered and the diskette stored

in its cover envelope while not being used. Precautions should be

taken to protect the diskette from any magnetic sources or sources of

extreme heat. Shipping standards range from -40° to 125°F. Although

data will not be lost outside these temperatures, sufficient time for

cooling (min. 30 minutes) should be allowed to insure data accuracy.

In addition, care should be taken not to do pencil erasures around the

diskettes, since lead particles tend to cause severe damage to them.

When storing or shipping, measures should be taken to prevent the

diskette from sagging or leaning as this will tend to warp the

diskette, causing loss of data.

42
As magnetic storage becomes more compact, the need for disk

surfaces which can prevent loss of data Increases. Attempts have been

made to enhance the coercltlvlty by adding cobalt to the Iron oxide

coating. Various coatings are used, but none Is superior. In

addition to modifying the disks, attempts are being made to modify the

read-write heads to produce a more reliable recording media.

Magnetic tapes are extremely versatile and have become more

transportable due to the cartridge concept. These cassettes, similar

to an eight-track, provide an easy method of storing and transporting

large quantities of Information. The sidewinder tape was created

mainly for the purpose of backing up and storing Information from

Winchester drives, which contain as much as 20 M bytes of data.

It Is obvious that with the Increase In computer complexity

there will continue to be an Increase In software volume. Regardless

of the amount of care taken during packaging, storage and shipping of

software, the risk of errors may Increase during this dormant period.

Surface damage on magnetic disks Is becoming a larger problem with the

greater densities. Specks of dust on the reading heads of paper tape

readers, card readers, magnetic tape and disk drives cause errors

during the reading process. Attempting to read dirty or warped cards

may result in erroneous data. To protect against such errors, error

detection and correction codes have been Implemented in both hardware

and software. Alpha radiation in new, high density Integrated

circuits, as well as noisy telephone lines, lightning storms, and

dirty contacts on telephone switching equipment, are additional

reasons for including error detection and correction codes during

system design. There are numerous error detection and correction

methods in use today, a small but representative subset of which is

Included here. These Include parity, longitudinal redundancy check,

Hamming codes and cyclic redundancy check.

The simplest and most prominent error detection code used is

parity. Parity is used to deteirmlne whether the bits in a character

have been properly received. One additional bit is appended to each

character. In the case of odd parity, that bit is chosen so that the

number of 1 bits in the character. Including the parity bit, is an odd

number. Likewise, in the case of even parity, that bit is chosen so that the number of 1 bits in the character is an even number. If one bit is changed, the number of I's in the character will have the wrong

parity and an error will be detected. Parity on each character can detect only errors that affect an odd number of bits; i.e., characters

with one erroneous bit (or three, or five, etc.). Errors that affect an even number of bits will not be detected. Parity does not provide

any method of detecting which bit in a character is in error, and

therefore does not provide for error correction.

43
The next level of error detection Is known as longitudinal

redundancy check. One check character is computed per block of data.

Each bit, except the leftmost, in the check character is chosen such

that it and the bit in the corresponding position in each character

total an odd number of ones. In all characters, including the check

character, the leftmost bit is a parity bit as previously described.

Longitudinal redundancy check will detect multiple errors within a character as long as multiple errors do not occur in a column. If

double bit errors in characters occur simultaneously with double bit

errors in columns, then neither parity nor longitudinal redundancy

check will detect the errors.

Richard Hamming developed a code for error correction as well

as error detection, known as the Hamming code. In a Hamming code,

check bits are distributed throughout the character in such a way as to provide parity checks on various bit positions. The bits are numbered starting at 1, not 0, with bit 1 the leftmost bit. All bits

whose bit number is a power of 2 are parity bits. Each parity bit

checks multiple data bits. Hamming codes may be illustrated using a seven-bit ASCII character. Four parity bits are added such that bits

1, 2, 4, and 8 are parity bits, and bits 3, 5, 6, 7, 9, 10, and 11 are

the seven data bits. Each parity bit checks specific bit positions as follows

:

Bit 1 checks bits 1, 3, 5, 7, 9, and 11

Bit 2 checks bits 2, 3, 6, 7, 10, and 11

Bit 4 checks bits 4, 5, 6, and 7 Bit 8 checks bits 8, 9, 10, and 11

The parity bit is chosen such that the total number of l*s in the

checked bits is even. An error may be corrected by performing parity

checks in order and designating a successful check by a 0 and a failure by a 1. The position of the bit in error is determined by the

binary number formed by writing the check digits from right to left.

The state of that bit may then be inverted to correct the error. Through the use of Hamming codes double-error detection is

accomplished with single-error correction. Errors involving more than

2 bits per word may not be detected. Hamming codes increase the

memory requirements of a system significantly, adding one parity bit

for each power of 2 that the data word increases.

Another method of error detection is the cyclic redundancy

check (CRC). CRC requires no parity bit (or bits) per character, as do the previously mentioned codes, but there is a check character at

the end of each block of characters. The use of CRC is becoming more widespread with recent integrated circuit designs. The bit stream of

length K bits is represented by a polynomial with K terms. The bits

in the data stream are the coefficients in the polynomial. This

polynomial is sometimes referred to as the message polynomial. To

44
compute the CRC, another polynomial, referred to as the generating

polynomial. Is chosen of degree greater than zero and less than the

message polynomial and with a non-zero coefficient In the term.

Several standard generating polynomials exist, such as CRC-16 and CRC12. CRC-16 Is a 16-bit check character resulting from the generating

polynomial X^^ + X^ + X^ + 1 and CRC-12 is a 12-bit check character

resulting from the generating polynomial X^^ + X^^ + X^ + X^ + X + 1

.

The check character is computed by first multiplying the message

polynomial by X^ where r is the degree of the generating polynomial.

This multiplication will result in zeros in the lower r position of

the message polynomial. The check character will be appended to the

message in these positions. The product from the multiplication is

then divided by the generating polynomial, yielding a quotient and a remainder. The quotient is discarded and the result is added to the

product of the previously mentioned multiplication. This remainder is

the check character. The check character is stored with the data

stream for later verification. A practical application of the CRC

procedure is with the use of integrated circuits. A CRC may be

computed on the program to be stored in ROM with that CRC also stored

in ROM. Any time verification is needed that the program is intact,

for example upon power-up, the CRC may be recomputed and compared to

the stored CRC. If they are different, then an error has occurred.

Cyclic redundancy checks normally do not provide for error correction,

but they are an efficient and reliable method of error detection.

It is highly recommended that some method of error detection

and/or error correction be implemented in any system design. If the

software and/or data within a system are to be stored or shipped,

error detection techniques will aid in recognizing failures that occur during shipping and storage.

45
PACKAGING FOR THE TRANSPORTATION ENVIRONMENT

W. Duncan Godshall

U.S. Forest Products Laboratory

Madison, Wisconsin 53705

Adequate packaging is needed to protect products against the hazards of

the transportation environment. The level of packaging protection must

be sufficient to bridge the gap between the fragility level of the

product, and the highest probable level of hazard in the normal

expected transportation environment.

In order to design an adequate level of packaging, it is necessary to

define the anticipated environment.

The hazards of the transportation environment are most commonly perceived to be those associated with rail and truck transportation, such

as switching shocks and over-the-road vibration. Actually there are many other hazards, such as production line conveyor systems, pallet

trucks, clamp trucks, manual handling methods, and warehouse and

vehicle stacking forces. Many of these hazards can be controlled and

reduced by good packaging and material handling practices. An assessment of the common* carrier shipping environment is provided in Forest

Products Laboratory's General Technical Report, FPL 22.

The vast majority of non-bulk, non-hazardous products are packaged in

corrugated fiberboard containers and shipped via common carrier. Corrugated fiberboard has been a relatively stable, uniform product for

many years, with grade classifications based on carrier regulated packaging rules, which tacitly assumed the use of virgin softwood fiber.

With increasing demand, and limited availability of softwoods, greater

use is being made of excess hardwood and recycled fibers for corrugated

boxes. These fibers have different mechanical properties, so corrugated fiberboard boxes procured with the existing specification system

may have widely different performance characteristics.

Therefore, it is recommended that performance type tests, such as the

ASTM Recommended Practice for Performance Testing of Shipping Containers be used to evaluate packaging to ensure satisfactory and eco- nomical protection against the hazards of the shipping environment.

46
SESSION II

RESEARCH IN THE RAILROAD INDUSTRY

CHAIRMAN

:

JACKSON YANG

UNIVERSITY OF MARYLAND

IMPROVED SUSPENSION DESIGNS AND

THEIR INFLUENCE ON FREIGHT CAR DYNAMICS

P.V. RamaChandran

Wyle Laboratories

Colorado Springs, CO 80915

M.M. ElMadany

Wyle Laboratories

Colorado Springs, CO 80915

Abstract: An evaluation of freight car truck performance was accomplished

through the use of extensive field testing under revenue operating conditions.

The field test data were reduced £ind analyzed through the use of digital

computers. Results from the analysis were studied, and the performance

characteristics of premium design trucks were compared to those of conventional trucks. Incremental performance improvements, relating to freight car dynamics, were studied with the objective of relating them as a cause-andeffect relationship to specific design features in the truck suspensions. This

paper discusses the relationship of advanced features in truck suspension design

to mitigating effects on the mechanisms influencing wear and failure of vehicle

system components.

Keywords: Truck design features; Type I trucks; Type n trucks, premium

trucks; performance regimes; lateral stability; ride quality; trackability; freight car dynamics; suspension; vibration.

In the course of a recently completed applied research and evaluation project

sponsored by the Federal Railroad Administration, several state-of-the-art

design premium freight car trucks were studied and evaluated to determine

performance improvements [1]. Conventional, three-piece trucks were also

subjected to a parallel evaluation to provide a basis for comparison [2] • Overall

freight car truck performance was classified into four distinct performance

regimes, inclusive of lateral dynamics, vertical and roll dynamics, load equalization, and curve negotiation. The discussion in this paper considers these

performance regimes with the exception of curve negotiation with the intent to

relate rail car dynamics to vehicle system and component service life and

reliability.

The evaluation of freight car truck performance was accomplished through the use of extensive field testing under revenue service operating conditions. The

field test data were reduced and analyzed through the use of digital computers.

Results from the analysis were studied, and the performance characteristics of

premium design trucks were compared to those of conventional trucks.

Furthermore, incremental performance improvements, relating to freight car

49
dynamics, were studied with the objective of relating them as a cause-andeffect relationship to specific design features in the truck suspensions.

The objectives of this paper are (a) to review conventional freight car truck

design features, (b) to discuss truck performance and component deterioration,

and (c) to present the results on improved performance attainable through

improved suspension designs, with an attempt to relate the new features in

truck suspension design to mitigating effects on the mechanisms influencing

wear and failure of vehicle system components.

CONVENTIONAL (TYPE I) FREIGHT CAR TRUCK

Apart from track, the freight car truck has long been recognized as the most

critical component of the rail vehicle system. It supports the carbody and its

lading, guides it along the track, transmits braking forces, and isolates the car

to some extent from dynamic excitation caused by track irregularities. In performing these functions, the components of the truck suffer various forms of

deterioration, such as wear and fatigue failure, £3^

The design of the standard three-piece freight car truck, last improved by the

addition of friction snubbing in the 1930's, must be considered as an engineering, manufacturing, and economic achievement. It is relatively inexpensive to

produce in large quantities by casting. Its loose construction, i.e., the bolsterside frame and adapter-pedestal connections, make it tolerant of vertical track

irregularities (a property generally termed "equalization" which refers to the

load distribution over the four wheels when their contact points are not in a

plane). The truck's relatively few standardized components can be readily

stocked at repair facilities, and maintaining or repairing it does not require a

highly skilled labor force.

However, the demands made on the country's rail transportation systems have

steadily risen over the past few decades. The gross rail weight of freight cars has shown a continuing increase, which results in higher wheel loads and

accelerating deterioration of the track, while higher centers of gravity increase

the risk of derailment. In accommodating shippers' requirements, railroads

have introduced a number of new freight car configurations which, by virtue of

extreme inertial or structural properties, such as low torsional stiffness, or high

center of gravity, have given rise to problems of operation and maintenance

more severe than were the case for cars of more conventional proportions. In addition, maintenance and repair problems are aggravated by the high utilization rate of unit trains.

In summary, the three-piece, friction snubbed freight car truck, in one sense,

has evolved into an optimum configuration with respect to a number of criteria,

such as low production cost, high tolerance to rail irregularities (i.e., good load

equalization), and moderate wear. However, it must be clearly recognized that

some of the performance criteria are met only under the constraint of

relatively low speed and that some (like curving performance) are met much

less than others. Increasing speeds have brought out a number of problems such

as hunting and poor ride quality at high speeds.

50
TRUCK PERFORMANCE AND DETERIORATION

Figure 1 shows the frames of reference used to deal with the freight car truck.

The diagram is divided into two main domains, performance and deterioration,

with cost indicated as a factor in both. The interface between these two

domains is formed by the truck components.

Performance may be defined either in operational or in functional terms.

Operational descriptions include a combination of problem areas, phenomena,

regimes, and conditions. Some of these are indicated in Table 1. For example,

hunting may be considered a phenomenon, a dynamic regime, and a problem

area. Other major performance regimes listed are curve negotiation, harmonic

roll, ride quality, derailment, load equalization, braking response, and possibly

others. Under each major heading are listed some of the characteristics

associated with the particular regime. Such a classification of truck performance features is useful for demonstrating the range and variety of requirements, and there is probably little doubt as to the characteristics of the ideal

truck in any of these performance regimes. For example, all railroads would

like a high critical speed and low sensitivity to wheel profiles with respect to

hunting, and also a minimum flange force during curve negotiation. Unfortunately, the requirements for high performance in several regimes are frequently incompatible.

To reflect actual conditions, a realistic engineering analysis cannot be based on

the assumption that all of the components remain unchanged over a period of

time and perform their functions according to the equations describing them

when new. Almost all components of the freight car truck are subject to

various forms of deterioration. The deterioration in performance may be high

in proportion to the amount of metal removed or damaged. For example, a small change in wheel tread contour may greatly lower the critical speed as may a widening of the clearances between the bearing adapter and its seat in

the pedestal.

Deterioration is accepted as a reality inherent in freight car operation and is allowed for in maintenance schedules and repair facilities, as well as in

replacement budgets. Frequencies and rates of failure above the expected are cause for concern, especially when they occur in a particular type or class of

components.

The lower half of the freight car truck universe diagram (Figure 1) shows modes

or evidence of deterioration on the left, and mechanisms or causes of

deterioration on the right. Some of the major modes of deterioration are:

abrasion

plastic deformation

gross loss of material

change in properties

metal flow

surface/subsurface cracks

brittle fracture

dislocation

The more important mechanisms or causes are shown in Table 2.

51
52
Table 1. Truck Operational Characteristics

HUNTING

Critical Speed

Lateral Acceleration

Sensitivity To

- Wheel & Rail Contour

- Gauge

- Carbody Properties

CURVE NEGOTIATION

Axle Alignment

Lateral Wheel Loads

Wheel Climbing

Wheel Unloading

Resistances

HARMONIC ROLL

Critical Speed

Maximum Amplitude

Centerplate Liftoff

Buildup and Decay Rates

Wheel Lift

Snubbing

RIDE QUALITY

Shock

Vibration

Isolation/Transmission

Damage Potential

DERAILMENT

Wheel Climbing

Loss of Guidance (Wheel Lift) - Pre-Existing

- Forced

LOAD EQUALIZATION

Resistances

BRAKING RESPONSE

Crabbing

Table 2. Mechanisms or Causes of Truck Deterioration

Overload/Overstress

Fatigue

Impact

Thermal Stress

Sliding Friction - Unlubricated

Sliding Friction - Boundary Lubricated

Contact Stress

- Shear

- Fretting

- Stress Corrosion

Cutting

Manufacturing Flaw

Misfit

53
The identification of failure modes and mechanisms in more precise technical

terms may well facilitate the solution of such problems, again by relating them

to the existing technology.

Although deterioration shows up in individual components it must be treated as a system problem, just like performance, for the most effective solution. In fact, the aspects of performance and deterioration are connected and interact.

This interaction may be illustrated by considering the hunting phenomenon,

Figure 1.

Functionally, this is connected with a large number of engineering characteristics, shown on the right, which include the kinematics of both the suspension

and the wheel and rail, the stiffness of the truck and suspension, clearances in

all the mechanisms, and the characteristics of the carbody. The components of

the truck directly involved are the wheel tread and throat as well as some

properties of the rail, including profile and gauge, and surface condition.

The deterioration side of the diagram shows some of the possible modes and

mechanisms of damage that may be involved, such as metal flow and fracture in

wheels, dislocation of the rail due to lateral impact, impact at the gibs and the

rim of the center bowl, and center plate wear due to boundary lubricated sliding

friction. Another possible interaction begins with the configuration of the

brake rigging which influences the transverse location of the brake shoes with

respect to the wheel and is believed to affect the development of the worn

contour. This in turn can lead to large differences in critical speed, an effect

that has been verified in several road tests and in the analyses based on test

results.

The interaction between performance and deterioration for the case of hunting

is shown in Figure 2. Hunting in freight cars occurs when one of the lateral

natural frequencies of the carbody on its suspension comes close to the

kinematic frequency of at least one of the two trucks. Therefore, different cars with the same truck, or the same car with different lading, will not

necessarily become unstable at the same critical speed. When two identical cars with the same lading have widely different critical speeds, under the same

track conditions, this difference in performance can be shown to be due to

differences in the contours of the worn wheel treads which in turn are believed

to be produced by the characteristics of the brake rigging, and by differences in

the brake shoes themselves.

The contributions of these various factors to the development of stable and

unstable wheel profiles are not well known, and consideration is being given to

the construction of a test rig that will allow a more positive identification of

the importance of the various factors involved in the wear process. Thus, the

left side of Figure 2 represents a combination of known facts, such as the

dynamics of the spring mass system represented by the car, and the importance

of the effective conicity of the wheel profile, with conjectures concerning

changes in the system due to localized deterioration, that is, the removal of

small amounts of metal from the circumference in the wheel.

54
55
By contrast the right side of the diagram portrays the observable damage and

the resulting cost of repair or replacement. Such damage is caused by impact

between the wheel and rail, which may result in damage to both, as well as to

other truck components through which the impact forces are propagated, such

as the bolster gibs, the side frame columns and the center bowl. In severe

cases, the car structure may be fatigued and the lading damaged. In addition, if there is relative motion between truck components during impacts caused by

hunting there will obviously be abrasion and fretting, even fractures may occur.

Similar relationships between performance and deterioration aspects may be

established for other major performnace regimes of the freight car truck. The

consideration of these relationships is an essential basis for the establishment

of performance guidelines.

TRUCK DESIGN IMPROVEMENTS

The standard three-piece truck is highly serviceable, but by no means perfect.

Attempts to improve its performance and durability have a long history, with

both railroads and suppliers contributing novel components as well as entirely

new design concepts. The acceptance of these improvements is impeded not

only by their unavoidably higher initial cost, but by the difficulty of justifying

this cost in terms of improved performance.

While many details on truck performance and deterioration remain to be dealt

with quantitatively, there exists a basis of knowledge and data sufficient to

suggest major improvements in design. These improvements are of two main

kinds:

o Modification of the three-piece truck by addition of special hardware

o Alternate truck configurations.

Modified Three-Pieee Trucks

A number of special components have been developed to improve the roll

dynamics of the carbody. Among these are constant contact side bearings,

center plate extension pads (C-PEP) and adjustable pneumatic side bearings (air

springs). Modifications of the suspension, intended to improve ride quality and

dampen harmonic roll, include augmented snubbing, through higher column

loads, by additional dampers inserted in the spring nest, or by hydraulic

dampers.

Several approaches have been tried to improve lateral stability. Apart from

larger center plates, which increase resistance to truck swivel, such modifications include hydraulic dampers between the carbody and truck bolster, or between the truck bolster and side frames, and structural ties between the side

frames to reduce parallelogram ming. The rigidity or resistance of these

devices required to maintain the truck in tram against the moments applied by

creep forces appears in general to have been underestimated.

56
Alternate Truck Designs

Almost without exception, all Type II (premium) trucks are made up of two side

frames connected at their centers by a member analogous to the bolster of the

Type I (conventional) trucks. What distinguishes alternate truck designs from

each other, and from the conventional trucks, are the nature of the side

frame/bolster connection, the suspension, and in a few cases, the method of

supporting the carbody. These differences exert a significant effect on truck

performance, in the four performance regimes of curve negotiation, lateral

stability, ride quality, and load equalization.

The goals of the new suspension design premium trucks are to provide higher

safe operating speed, greater load-carrying capacity, improved ride quality,

reduced damage and deterioration to vehicle components, and reduced wheel

and rail wear. To fulfill these goals, each truck possesses certain design

features. An evaluation of the different design innovations was accomplished

through field testing and test data analysis of both Type I and Type II trucks. In the following sections the performance regimes are discussed, the Type I and

Type n performance characteristics are presented, and the incremental performance improvements relating to freight car dynamics are studied with the

objective of relating them as a cause-and-effect relationship to specific

features in the truck design. • PERFORMANCE REGIMES

Results relating to the three performance regimes of lateral stability, ride

quality, and trackability are discussed in this paper. These performance

regimes are described below.

It is known that hunting is a safety as well as an operational problem. The large

relative motions of components in a hunting truck cause accelerated wear,

impact between wheel flange and rail cause gauge widening, and pose the

danger of wheel fracture. Severe lading damage can be caused by the lateral

vibration of the carbody. The elimination or reduction in severity of hunting is, therefore, economically important because of the damage it causes to both

lading and vehicle components.

Ride quality is an important characteristic of a rail vehicle, since it refers to

the effectiveness with which it is able to transport lading with minimum

damage, both to the lading and to vehicle components. In engineering terms,

ride quality is expressed as the response of the carbody to excitations arising

from track irregularities. From the operational point of view, ride quality is a function of the transmissibility for shock and vibration which is functionally

determined by the spring and damping rates of the suspension, by the load

paths, and by the magnitudes of the sprung and unsprung masses. The chief

difficulty in optimizing the suspension and improving ride quality is the wide

range of loading conditions, between an empty and a fuUy loaded car. Springs

must obviously be designed for maximum combined static and dynamic loads,

and dampers for maximum energy dissipitation, but these result in a "hard" ride

for the empty car. Other constraints include the limited space available in the

57
side frame and manufacturing inaccuracies that modify the performance of even new suspension elements, such as out-of-square springs.

Trackability is the ability of the truck to maintain sufficient loads on all wheels

to allow the development of guidance forces which prevent derailment for all

extremes of in-service track geometry. The trackability regime discussed in

this paper includes, as subsets, the ability of the truck to accommodate; (a)

track twist, and (b) curve entry and exit (spirals). This ability is important for

successful negotiation of low sidings, poor track in switch yards, and transition

from the tangent to curve track for a wide range of operating and

environmental conditions.

Typical results are shown in Figures 3 through 7, and in Table 3. The design

features of each truck are evaluated and the performance is compared with

Type I trucks in the following sections.

TRUCK PERFORMANCE CHARACTERISTICS

A number of Type I and Type n trucks were road tested during Phase I, [4], and

Phase 11, 5,6 , of the Truck Design Optimization Project. The test data were

analyzed in TDOP Phase n to establish quantitative information on Type I and

Type n truck performance in the principal regimes of lateral stability, ride

quality, steady state curve negotiation, and trackability, Il,2].

Performance test data on the lateral acceleration of the test vehicles were

available at various locations on the carbody and trucks. Indications of

instability were identified from the time history data and from the power

spedtra. The power spectra were scanned in the range of 0-5 Hz and the

characteristic frequency of hunting was identified. Centered around this

frequency, root mean square (rms) accelerations were calculated for a bandwidth of 1 Hz. The calculated rms values for lateral accelerations were then

plotted as functions of operating speed. Typical results are shown in Figure 3.

The high speed tangent track test runs were used in the analysis of the ride

quality. Performance in this regime is given by the rms response over the wide

band spectrum (0-20 Hz) as a performance index. Figures 4 and 5 give the

carbody rms vertical and roU accelerations, respectively, as functions of

vehicle speed.

Analysis of data in the trackability regime fell under the subregimes of track

twist, and curve entry/exit. The wheel unloading index has been quantified for

the track twist and curve entry/exit subregimes.

The wheel unloading index is defined as follows:

WUI = 1- Wj^/W^/3

where; Wj^ = vertical force on most lightly loaded wheels

Wtt = sum of vertical forces on the three most heavily loaded wheels.

58
s.o 'NOiivusiaoov ivoLLdiA sm

8.0 'NOiiVdaiaoov ivaaivi swu

59
Table 3, Wheel Unloading Index (WUI) Levels

(Track Twist)

T7 mnt\7 r^nr

Truck WUI95

Dresser DR-1 0.783 0.281

Swing Motion 0.553 0,368

Maxiride-100 0,297 0.307

Type! 0.351 0.364

O 50

CO

UJUJ

cco

HIQ

z

o

p<

cr

ui

_iu

u

<o

a.s

cc

40

30 -

20

10

0.030

\ " 1—~—

r

A DRESSER DR-1 ^ SWtMO MOTION 9 MAXIRIOE-100 ACF FABRICATED

40

J. 50 60

SPEED.MPH

70 80

Figure 5. RMS Roll Acceleration For Loaded

Cars Versus Speed

60
XaONI 9Nia\/01Nn 133HM dO 13AJ1 ZS6

61
Data relating to the track twist subregime consisted of yard track tests and

those relating to curve entry/exit consisted of the segments of curved zone test runs representing the entry and exit spirals associated with each of the curves

in the test track. The quantified levels of the wheel unloading index for the

track twist are provided in tabulated format, Table 3. For the curve entry/exit

subregime, values of the wheel unloading index with associated probability of occurrence of 95% are plotted as functions of speed, as shown in Figures 6

and 7. IMPROVED DESIGN FEATURES AND RESULTING PERFORMANCE

As can be seen in Figure 3, which gives the rms lateral accelerations of the

carbody as functions of operating speed, while the Type I truck exhibits severe

hunting motion in the speed range of 70 to 79 mph, the Type II trucks undergo

only low amplitude intermittent hunting in the corresponding speed range, with

the lateral motions of the carbody well controlled.

The attenuation or prevention of hunting by using Type H trucks is accomplished

through several different techniques. These techniques include decoupling the

carbody from the truck (kinematic modification), rigidizing the truck in tram,

and energy absorption. Decreasing the lateral suspension stiffness of the truck

modifies the vehicle system kinematics and removes the body mode frequencies

from the range of kinematic hunting frequencies, thus reducing the synchronization between the carbody and truck motions. Decoupling between the

carbody and truck can also be achieved by using hydraulic snubbers. In Type I trucks, the lateral forces on an empty or lightly loaded car may be too low to

overcome breakout friction, which may lead to flange impact as the carbody

and truck displace laterally as one rigid body. In using hydraulic snubbers to

dissipate the energy, however, provision should be made to provide damping in

both the vertical and lateral directions. Mounting the hydraulic absorbers

vertically only may cause a resonance phenomenon in the medium speed range

of 40 to 60 mph with very high lateral motion that may result in damage to

vehicle components.

The complete rigidization of a truck (i.e., rigidizing the truck in tram by means

of an intertie between the side frames or steering arms capable of reducing

parallelogramming action of the truck) is bound to affect truck performance by

stabilizing it against hunting, and has a noticeable beneficial effect on the

lateral motions developed at high operating speeds.

Increasing truck swivel resistance, either by means of larger center plates

supporting the entire load on the side frames or constant contact side bearings,

inhibits sustained lateral oscillations. The use of ducQ-rate springing suspension

may also contribute to truck stability.

From the foregoing discussion, it may be said that altering the kinematics,

stiffening the truck in tram (i.e., high warp rigidity) and extent of energy

dissipitaion in truck swivel can result in attenuating truck hunting and raising

the critical speed.

62
The uniform riding qualities provided by Type n trucks are due to several

features implemented in their designs. A reduction in the unsprung mass, for

example, greatly improves vertical ride quality. This is achieved by placing the

suspension over the axle (primary springing), thus reducing the unsprung mass to

that of the wheelsets, bearing, and adapters. The use of dual-rate suspension

characteristics that modify the vertical and lateral behavior of the empty car can provide smooth ride in both the lateral and vertical directions in empty and

loaded conditions. The ride motion can also be improved by decoupling the

vertical motion from the lateral motion, and by reducing the spring rate with

the use of longer spring travel combined with the load-sensitive friction snubber

wedges that damp the vertical and lateral motions of the bolster.

On the other hand, in general, the Type I truck has better performance in the

track twist and curve entry/exit subsets of the trackability regime than many

of Type n trucks. Accommodation of vertical track irregularities is an acknowledged advantage with the Type I truck featuring loose construction at

the bolster-side frame and adapter-pedestal connections. The ability to

maintain adequate vertical load distribution under cross-level irregularities is impaired in Type n trucks. Increasing truck swivel resistance by dissipative

means promotes derailment in curves due to inadequate vertical wheel loads

maintained under simultaneous lateral forces.

It may be stated that modifications made to improve an aspect of truck

performance frequently leads to impairment in another operating regime.

Therfore, in an overall judgment of any particular truck, its relative standing in

all regimes must be considered, and such judgment may be heavily influenced by

each railroad's particular operating conditions and practices.

Within the limitations of the Type 1 truck, improvements in vertical ride quality

appear achievable mainly through modification of the load path. Constant

contact side bearings appear to decrease maximum shock loads due to roll. Dual rate springs would improve the ride quality of the empty car, but are apparently difficult to accommodate in the standard truck. Hydraulic shock

absorbers would improve the vertical ride; however, provision should be made to

provide some damping in the lateral direction. , . Some premium trucks incorporate improved load paths. Supporting all of the

load on the side frames provides greater lateral stability which benefits the

lateral ride quality. The lateral ride quality of some Type 11 trucks is achieved

by kinematically softening the lateral spring rate.

IMPUCATIONS FOR MITIGATION OF FAILURE MECHANISMS

An essential requirement of the freight car truck is that it must perform in

different environment (transitions from tangent-to-curved track, from continuously welded to jointed rail, crossings, turnouts and bridges, and changes in

the total gross rail weight) in a state of increasing deterioration, which is brought about by its interaction with the operating environment. In the

standard three-piece truck, the only precision components are the roller

63
bearings, the journals of the axles on which they are mounted, and the surfaces

of the adapters that mate them with the truck. All other components, such as the center bowl, friction snubbers, gibs, and the adapters themselves, transmit

loads by metal-to-metal contacts through surfaces capable of moving relative

to each other (sliding) or normal to each other, through clearances. The

resulting deterioration of these highly loaded connecting points or interfaces

represents a large cost to the industry because repairs or replacements must be

made to ensure safe operation and prevent delays. In addition, the changes in

clearances as the connecting surfaces wear or deform changes the kinematics

of the truck as a mechanism.

These changes have a profound effect on the dynamic response of the truck and

the railcar body to the conditions of the track described above. For example,

wear of the friction snubber shoe decreases the resistance to harmonic roll and

thus results in increased probability of derailment when the vehicle is crossing

staggered rail joints at certain critical speeds. Snubber wear also decreases the

yaw stiffness of the bolster-side frame connection; the resulting increase in the

degree of parallelogram ming increases the angle of attack of the leading

wheelset during curve negotiation and thus leads to increased wear of both

wheels and rails. Comparable changes in truck performance can be associated

with almost every other group of components.

Wheels, brakes, and rail interact to produce complex wear patterns that affect

performance long before components are changed or repaired to ensure safety

of operation. As with the other examples given above, the cost of impaired

effectiveness due to deterioration is not easy to establish since the mechanism

of damg^e cannot be viewed in action and may be inferred by analysis of such

damage. ,

Improving the truck suspension systems through the use of the different design

features, wiU reduce or attenuate the severity of hunting and provide smooth

ride quality. This will result in less wear to wheel, rail, bearing adapters, gib

clearance, etc., less impact between wheel flange and rail, thus eliminating

gauge widening, reducing the mechanical damage to vehicle components, and

mitigating the deterioration not only to the various components making up the

rail vehicle, but also the track.

64
REFERENCES

1. RamaChandran, P.V., and ElMadany, M.M., "Truck Design Optimization

Project Phase n - Performance Specification for Type n Freight Car Trucks",

Report No. FRA/ORD-8 1/36.1., August 1981.

2. RamaChandran, P.V., and ElMadany, M.M., "Truck Design Optimization

Project Phase n - Performance Characterization of Type I Freight Car Trucks",

Report No. FRA/ORD-81/10, January 1981.

3. Cappel, K.L., "Truck Design Optimization Project Phase U - Introductory

Report", Report No. FRA/ORD-78/53, November 1978.

4. Southern Pacific Transportation Company, "Freight Car Truck Design

Optimization Phase I - Final Report", Report No. FRA/ORD-78/12.II.

5. Gibson, D.W., "Truck Design Optimization Project Phase II - Type II Truck

Test Procedure", Wyle Laboratories Report No. C-901-0010-A, June 1980.

6. Gibson, D.W., "Truck Design Optimization Project Phase II - Type H Truck

Test Results Report", Wyle Laboratories Report No. C-901-0012-A, 1981.

65
DEVELOPMENT OF SMALL SCALE IMPACT SIMULATION TECHNIQUES

J. Chen and N. G. Dagalakis

Advanced Technology & Research, Inc.

Silver Spring, Maryland 20904

ABSTRACT

In derailments and switchyard operations, tank cars carrying hazardous

materials frequently experience impacts that result in impairment of

the structural integrity of the tank car. Because of the large com- bination of tank car configurations and credible impact scenarios, it

is not feasible to conduct full scale testing to verify that a particular tank car design will perform satisfactorily in impact situations.

Therefore, there is a need for reliable small scale testing procedures

to simulate the response of tank cars in impact situations.

Initial evaluation of tank car structures under impact was done utilizing an energy method based on Hertz contact stress energy. Dimensionless parameters were identified in this study to form the basis of

scaling. Among the quantities that constitute these parameters were

tank car dimensions, loading, impact speed, and others. Finite element

ancilyses of the impact of tank cars were then performed to modify the

scaling law obtained.

66
A METHOD TO DETECT AND MONITOR CRACK IN BRIDGE STRUCTURES

Jackson C. S. Yang, Professor

University of Maryland

College Park, Maryland 20742

Manfred A. Hirt, Professor

Ecole Polytechnique Federale de Lausanne, Switzerland

ABSTRACT

The problem of detecting crack in bridge structures is studied

with the use of Random Decrement analysis. Fatigue tests were performed on several 3300 mm steel beams using the program controlled

load simulator at the Institute of Metal Construction, EPFL, Switzerland, Inputs to the simulator were obtained from actual measurements

from various traffic patterns throughout Switzerland. A special

technique utilizing pre-stressed thin wires mounted on the specimen

was used to detect the initiation of crack in the specimen. The

breakage of the wire automatically stops the simulator. Crack propagation resistance gages were then mounted on the specimen to monitor

the growth in the size of the crack as the test is continued.

Accelerometers were attached to the specimen and responses were

recorded periodically before and after the initiation of crack. These

time history responses were used as inputs in the Random Decrement

method to obtain the Random Decrement signatures. The change in shape

of the signatures was correlated and compared to the experimentally

determined crack initiation and growth to test the ability of the

Random Decrement method to detect and monitor an unknown crack from

the random data.

RANDOM DECREMENT TECHNIQUE

Random Decrement was developed by H. A. Cole for the measurement

of damping and detection of structural deterioration of airplane wings

subjected to wind flutter excitation (1,2). Further research has been

done using the technique for crack detection and damping determination

by Yang and etc. (3-14).

Random Decrement technique is a general method of analysis which

is particularly suited to the class of problems in which characteristics are desired of inservice structures to unknown random excitation.

The major advantage of this technique is that it requires only

measurements of the dynamic response of the structure and not the

input excitation causing the response. On bridges such random input

forces occur from wind and traffic.

67
The analysis of a time-history response taken at some location

on a structure produces a signature which is dependent on structural

properties such as natural frequencies and damping. This signature

is sensitive to changes in these structural properties and thus offers

a means for detecting changes. The method analyzes the measured

output of a system subjected to some ambient random input. After

analysis, a signal results which is the free vibration response or signature of the structural system. The ability to obtain unique

response signatures for different modes (usually accomplished by

filtering the output) enables detection of early damage before overall

structural integrity is affected. Figure 1 illustrates the acquisition

of Random Decrement.

The Random Decrement cracks show up as small blips in the "hashy"

high modal density region of the response spectral density and as they grow, the failure mode frequencies become lower and approach the

fundamentals where failure becomes imminent. Flaws must be detected

early enough - that is, at high enough frequencies - if corrective

action is to be taken. Detection is accomplished by passing a random

response signal through a bandpass filter which is set to screen high frequencies. If a failure develope, the signature will be

affected dramatically because it will dynamically couple with structural

modes within these bandpass frequencies.

EXPERIMENTAL TEST

Fatigue tests were performed on several 3300 mm steel beams with

gusset plates using the program controlled load simulator at the

Institute of Metal Construction, EPFL, Switzerland (see Figure 2).

Details of the test beam and the solder goussets are presented in

Figures 3 and 4 respectively. The objective of the testing program

was to induce fatigue cracks into welded test specimens and to record

the vibration responses at various stages of crack growth.

The desired responses were to be of a random nature with fairly

uniform and wide frequency spectrums to which the Random Decrement

procedure could be applied. To obtain this type of response, two

different methods of randomly exciting the specimens under constant

load conditions were tested:

(1) actual measurements from various traffic patterns programmed

through the grips by the simulator, see Figure 5;

(2) continuously tapping on the specimen with the metal tip of a hammer, see Figure 6.

A special technique utilizing pre-stressed thin wires mounted on

the specimen was used to detect the initiation of crack in the specimen.

The breakage of the wire automatically stops the simulator. Crack

propagation resistance gages were then mounted on the specimen to

monitor the growth in the size of the crack as the test is continued.

Two B & K accelerometers were positioned on the specimen as shown in

68
Figure 3. Responses were recorded periodically before and after the

initiation of crack. These time history responses were used as inputs

to the Random Decrement method to obtain the Random Decrement signatures. A block diagram of the analysis of the recorded response

signal using the Random Decrement technique is given in Figure 7.

TEST RESULTS

Random Decrement signatures were obtained from the various time

history responses for two frequency ranges, 400 Hz to 800 Hz, 800 Hz

to 2000 Hz, using bandpass filters. A number of Random Decrement

signatures were obtained for each stage of crack propagation in order

to confirm the repeatability of the Random Decrement signatures.

The repeatability of the Random Decrement signatures were excellent.

This is very essential for the success of the Random Decrement

technique in the detection of flaws and cracks in structures.

The Random Decrement signature for the no crack condition is

shown on Figure 8. This signature is to be used as the baseline for

comparison purpose. The Random Decrement signatures for each crack

condition are shown on Figures 8-12 together with the baseline signature.

Changes in the signatures initiated and became increasingly

obvious when the crack length became larger and when multiple

cracks initiated. The relative deviation of each signature from the

baseline signature is given on each figure and summarized in Table 1.

The crack length and its condition together with the number of cycles

of fatigue loading are also presented in Table 1. A drawing of the

crack positions is given in Figure 13. As observed from Table 1,

the change in the signature at the crack length of 6.7 mm is sufficiently large to be able to use as a working device.

CONCLUSIONS

Several features of Random Decrement Analysis should be pointed

out : - V • . .

- A very important feature is that the random excitation f(t) does

not affect the shape of the Random Decrement signature and does not

need to be known,

- From this it can be concluded that the natural excitation can be

used for the analysis as long as it is reasonably random. This

has the advantage that any structure can be tested on-line and does

not have to be taken out of service for inspection. -

- Random Decrement examines the structure in its entire integrity

and can therefore detect surface cracks as well as inside defects.

- Random Decrement is applicable for both laboratory and field tests.

The simple equipment used for the recordings of the response signal

69
make it feasible in many surroundings.

- The recording of response signal takes usually a very short time

and can be performed even by untrained people. The main part of

the analysis can be done in the laboratory under constant favorable conditions.

The Random Decrement signatures obtained from a fatigue crack

introduced in a structure is consistent and repeatable. Signatures obtained from each crack depth agreed reasonably well with

each other.

- Change in the crack depth as small as 6 mm of the model structure

can be detected with the Random Decrement technique.

- The Random Decrement signatures demonstrated a marked change in

their patterns when the crack depth reached 6 mm, which is con- siderably far ahead from the complete failure of the structure,

- It appeared to be feasible to use the Random Decrement technique

for early detection of incipient flaws and cracks in structures.

ACKNOWLEDGEMENTS

This work was supported by N.S.F. , the Swiss N.S.F. and by the

Ecole Polytechnique Federale de Lausanne, Switzerland, as part of a major effort to develop better and more reliable techniques to insure

the safety of structures,

REFERENCES

1. Cole, H.A., Jr., "Method and Apparatus for Measuring the Damping

Characteristics of a Structure", United States Patent No.

3,620,069, Nov. 16, 1971.

2. Cole, H.A, , Jr., "On-Line Failure Detection and Damping Measurement of Aerospace Structures by Random Decrement Signatures",

NASA, CR-2205, 1973.

3. Kummer, E. , "The Detection of Fatigue Cracks in Structural

Members by the Random Decrement Technique", M.S. Thesis, University of Maryland, 1979.

4. Caldwell, D.W., "The Measurement of Damping and the Detection

of Damage in Linear and Nonlinear Systems by the Random Decrement Technique", Ph.D. Thesis, University of Maryland, 1978.

5. Caldwell, D.W., "The Measurement of Damping and the Detection

of Damage in Structures by the Random Decrement Technique",

M.S. Thesis, University of Maryland, 1975.

70
6. Yang, J.C.S., and Caldwell, D.W., "A Method for Detecting Structural Deterioration in Piping Systems", ASME Probabilistic

Analysis and Design of Nuclear Power Plant Structures Manual

PVD-PB-030, 1978, pp. 97-117.

7. Yang, J.C.S. and Caldwell, D.W., "Measurement of Damping and the

Detection of Damages in Structures by the Random Decrement

Technique", 46th Shock and Vibration Bulletin, 1976, pp. 129-136.

8. Yang, Jackson C.S,, Dagalakis, Nicholas G., Hirt, Manfred,

"Application of the Random Decrement Technique in the Detection

of Induced Cracks on the Off-Shore Platform Model", Computational

Methods for Offshore Structures. Special Publication AMD-Vol . 37

of the ASME (American Society of Mechanical Engineers) , Library

of Congress #80-69180, 1980.

9. Li, C.S., Yang, J.C.S. , Dagalakis, N.G. and Messlck, W.

,

"Similitude Analysis and Testing of Prototype and 1:13.8 Scale

Model of an Off short Platform", Shock and Vibration Bulletin, 51,

Part 1, pp. 195-216, May 1981.

10. Yang, Jackson C.S., Dagalakis, Nicholas, "Detection of Incipient

Failure in Structure Using Random Decrement Technique", Proceedings of the Fall Meeting of SESA (Society of Experimental Stress

Analysis), pp. 43-47, Oct. 12-15, 1980, Fort Lauderdale, Florida.

11. Kummer, E, , Yang, J.C.S., and Dagalakis, N., "Detection of Fatigue

Cracks in Structural Members", Proceedings of the Second ASCE

(American Society of Civil Engineers) /EMD Speciality Conference,

pp. 445-460, Jan 15-16, 1981, Atlanta, Georgia.

12. Yang, J.C.S., and Dagalakis, N.G., "Novel Technique Being Explored

to Warn of Impending Failures of Operating System", (Summary),

Journal of the Acoustical Society of Amer. Supplement 1, Vol. 68,

Fall 1980, Los Angeles, California.

13. Yang, J£.S., Aggour, M.S., Dagalakis, N., and Miller, F. , "Damping

of an Offshore Platform Model by Random Decrement Method",

Proceedings of the Second ASCE (Amer. Soc. of Civil Eng.) /EMD

Speciality Conference, pp. 119-132, Jan. 15-16, 1981, Atlanta, GA.

14. Yang, J.C.S., Dagalakis, N.G., Everstine, G., and Wang, F.Y.,

"Measurement of Structural Damping Using Rampant Decrement

Technique", to be published in the Shock and Vibration Bulletin,

S-2, November, 1981.

71
TABLE 1 - SIMMAEY OF TEST RESULTS (800 Hz-2000 Hz)

Fo. Relative Deviations

Cycles Position 1 Position 2 Crack Condition

1. 50,000 No Crack

d • ooQ r\r\r\ ddO , UUU An c: 0*30

. UUpOo9 . UU'+UUO INO Crack

3. 2^7,329 .006300 .009302 = Detection

\, 309,350 .029260 .030710 \

= 6.7 mm.

= Detection,

= 2.5 mm

5. 310,000 .033790 .036020 \

= 11.2 mm.

= Detection

6. 367,000 .027220 .027930 h

= 18.0 mm

Figure 1 - Acquisition of Random Decrement Signatures

72
Figure 2 - Program Controlled Load Simulator

(Institute of Metal Construction, EPFL, Switzerland)

BEAM FOR FATIGUE TEST

20 POUTRES POUR ESSAIS DE FATIGUE

3300

ZZL

50

Top

Flange

50

1550 1550

130

^^i=> J3tl«0i( B

^^J=3 170112 -H

130

1 1 II 1 l_ ^\cz= I70II1 V oia

Profile

Bottom

Flange

Figure 3 - Details of Fatigue Test Beam

73
Vertical Section on Support A-A Vertical Section at Truss B-B

l"60^'|lo*j

170 31 \ 1"

Detail of the Solder Qoussets

Figure 4 - Details of the Solder Goussetts

j

v -w --^^

i

t

« * « ,

Figure 5 - Programmed Traffic Patterns

74
Figure 6 - Hammer Excitation

Figure 7 - Random Decrement Analysis Set-Up

75
0.00 1*00

TIME <MSEC)

1.99 2.99

Figure 8 - Random Decrement Signatures (Base Line - Case 1)

0.00 1.00

TIME (MSEC)

1.99

\ y- BASE LINE

CASE 2?

w

:.99

Figure 9 - Random Decrement Signatures (Base Line - Case 2)

76
/- BASE

i / r

LINE

CASE 3

I \ /

\ ly

-4

I r\—^

\ If y\\//V

OoOO 1.00

TIME (MSEC)

1.99 !,99

Figure 10 - Random Decrement Signatures (Base Line - Case 3)

0.00 1*00

TIHE (MSEC)

1.99 2.99

Figure 11 - Random Decrement Signatures (Base Line - Case 4)

77
Figure 13 - Number and Crack Positions

78
RAILROAD LONG-TERM MAINTENANCE-OF-WAY

PLANNING TECHNIQUE DEVELOPMENT PROGRAM

A. Gross

Federal Railroad Administration

Washington, DC 20590

Abstract: This paper describes the cooperative Federal Railroad Admini

stration (FRA) - Conrail research program to develop techniques for

long-term track maintenance planning that will better utilize the

limited maintenance-of-way (MOW) resources and improve the quality of

rail service and overall track safety. This research program makes use of FRA's track geometry cars and other related data (traffic, physical,

maintenance) to determine track degradation and develop analytical

techniques for planning expenditures for track maintenance.

Key words: Track deterioration; track safety research; track maintenance planning; track geometry; maintenance-of-way; track quality

indices.

One of the major operating expenses of today's railroads are those

costs related to track maintenance to assure a safe and productive

railroad operation. Every railroad must decide where to devote its

limited track maintenance budget in the most cost-effective manner with

out allowing deterioration of track into unsafe or inefficient con- ditions. As part of a cooperative research program with Conrail, the

Federal Railroad Administration (FRA) is developing engineering techniques to help assure that track maintenance resources (greater then

$4 billion per year for the industry) are utilized in an optimum manner

to improve overall railroad system safety and service. This research

will also identify track geometry variations and the allowable relevant

vehicle speed limits, in relation to derailments and accidents due to

wheel climb, wheel lift, and excessive vehicle motion.

To assist in this research, the FRA is using high speed track geometry

measurement vehicles to collect detail track data.

Track Geometry Measurement Vehicle

Track geometry measurement vehicles have a long history in the United

States. In 1886, the Chesapeake and Ohio Railroad operated the first

domestic track inspection vehicles. Through the years, these track

geometry vehicles have become automated and sophisticated in measuring

79
and recording the following basic track geometry parameters;

° Gage - the distance between the two rails in a track structure

measured at five-eights of an inch below the top of the railhead.

° Profile - the measurement of the vertical position of each

railhead in a track structure.

° Alignment - the measurement of the lateral position of each

railhead in a track structure.

° Crosslevel - the difference in elevation between the left and

right rails.

° Curvature - the measure of the angular rate of change in track

direction.

FRA has been developing track geometry measurement and analysis techniques since 1967. Since that time, FRA began its Automated Track

Inspection Program (ATIP), a program in which track geometry vehicles

systems (T1-T3, T2-T4, T6 and TIO cars) are used at high speeds to

inspect track and monitor compliance with FRA Track Safety Standards.

Between 1971 and 1978, the FRA track geometry vehicle systems were employed in a joint Government-industry development program to investigate the use of the data generated by the track geometry cars in

maintenance planning. The data from regular annual or semi-annual

track geometry car surveys were supplied to two cooperating railroads

(the Denver and Rio Grande Western and the Bessemer and Lake Erie).

The railroads utilized the data to supplement their traditional maintenance and planning methods, and reported which track geometry

statistics (termed Track Quality Indices or TQI's) they found most useful, and how these data were used. (1) In general, the end product was

a system that could produce a detailed report of exceptions to the 1972

FRA track standards and railroad-selected geometry standards, as well

as other geometry-based indices. These indices were used by the

engineering staff of the participating railroads to direct emergency

spot maintenance and plan longer term maintenance.

FRA/Conrail Cooperative Research and Development Program

On the basis of the cooperative research programs findings and successes (described above) in early 1978, FRA initiated a major

cooperative research program with Conrail to investigate further the

use of track geometry data in track maintenance planning. The objectives of this continuing program are to find quantitative methods of

improving railroad safety and the cost-effectiveness of track mainte80
nance through analyses of track geometry data and other necessary data

(i.e., traffic, track type, and maintenance data), and prediction of

track deterioration. This cooperative study has developed into three

phases.

In the Phase I study, completed in June 1980, (2), two test track zones totaling approximately 290 track-miles were chosen as being typical of

mixed freight operation. One was in Conrail's Fort Wayne Division,

between Van Wert and Bucyrus, Ohio, and the second in the Lehigh

Division between Bound Brook, New Jersey, and Penn Haven Junction,

Pennsylvania. The Lehigh Division consists mainly of Class 2 and 3

track and annually carries between 7 and 14 million gross tons (MGT).

A significant portion of the track is curved and has steep gradients.

The Fort Wayne Division consists mainly of Class 3 and 4 tangent, lowgradient track and carries tonnage in the range of 18 to 25 MGT. This

test track was observed during 1978 and 1979, the Phase I study period,

and traffic and maintenance parameters were uncontrolled.

In 1978 and 1979, physical parameters data were collected in order to

determine their contribution to track degradation. Table 1 divides the

physical parameters into three areas: track structure, traffic, and

maintenance. These parameters were selected on the bases of previous

studies, experience, and cost of data acquisition. The structure parameters were quantified for the period of observation; the traffic and

maintenance parameters were quantified between the observations.

Traffic parameters consisted of annual tonnage, heavy wheel loads and

posted speed. Annual tonnage and heavy wheel loads were quantified for

the test zone by a seasonal sampling method. Train speed information

was obtained from track charts and timetables. The heavy loads were

determined by adding all the carloads above 90 tons and then calculating the percentage of the total annual tonnage.

Track charts were used to determine the rail weight and rail type

(bolted or welded). The curvature was quantified using curvature data

collected by the FRA T-6 vehicle. Rail profile, ballast, and drainage

condition were quantified by using field observations related to

specified criteria. The rail profile was defined as the percentage of

the surface bent rail in a bolted track segment. The ballast condition

was designated as clean, dirty, pumping, and fouled. The drainage

condition was designated as adequate or inadequate.

Maintenance practices were divided into two broad categories--basic and

discretionary. The basic maintenance operations were regaging, tie

renewal, hand smoothing, machine smoothing, and surfacing. Quantifying

basic maintenance was accomplished by determining the percentage of the

track segment that had received maintenance. The discretionary, or production maintenance, was categorized into three major operations;

surfacing, tie and surfacing, and rail renewal.

81
TABLE 1

PHYSICAL PARAMETERS

Category Type Units uurva ture Degrees

Rail Weight Pounds/Yard

Track Rail Type Bolted/Welded

Structure Ballast Condition Clean, Dirty, Pumping

Fouled

Rail Profile Percent Bent

Drainage Abil i ty Adequate, Inadequate

Track Speed Miles per Hour

Traffic Cumulative Tonnage Million Gross Tons

Heavy Loads Percent

Maintenance

Basic Maintenance

Production Maintenance

Levels 0, 10%, 30%, above

30%

Surface, Tie and Surface,

Rail Renewal

82
The test zone was divided into segments that were homogeneous with

respect to the above physical parameters. In this case, homogeneous

means that a physical parameter, such as tonnage, is constant throughout the segment. The entire test zone was divided into 676 variable

length segments, ranging from 0.1 mile to 1 mile.

Track geometry surveys were made in the autumns of 1978 and 1979, the

FRA T6 car measured all geometry parameters including alignment at one foot intervals; and intervening traffic, maintenance and track type

data were recorded. From the track geometry parameters, figures of

merit, referred to as Track Quality Indices (TQI's), were computed. A

TQI objectively quantifies one aspect of track condition and is a statistical sunmary of a track geometry parameter measured over a prescribed length of track. The TQI effectively summarizes the large

number of measurements of each parameter for a given track segment.

Sample statistics such as mean, ninety-ninth percentile, standard

deviation, and higher order moments were investigated in this study.

Figure 1 shows a TQI rating of a track segment in a relative manner.

In this example, profile is used; however, all track geometry parameters can likewise be applied. The horizontal dashed line represents

perfectly smooth track; the solid line represents the actual measurement; and the shaded regions represent the area between the actual

profile and smooth track. A figure of merit for profile roughness can

be calculated by taking the square root of the average area. A TQI

with a high relative value of 0.5 inch (for example), depicts poor

track condition; a TQI with a low relative value of 0.2 inch indicates

good track condition. In this example, the profile TQI is the standard

deviation in a statistical sense and indicates the profile roughness.

Figure 2 illustrates how a TQI can be used in long-range maintenance

planning. The track condition at time t] is indicated by TQI]. If

the curve, a TQI track degradation model, is known, the condition of

the track at time t2 (TQI2) can be projected as a function of physical

parameters such as tonnage and rail type.

A total of 14 TQI's were selected as representing the functional re- quirements of track. These were reduced to five by correlation

analysis: one TQI was selected to represent each group of highly

correlated TQI's in the original 14. These are listed in Table 2. The

five TQI's are the gage roughness index, wide gage index, surface index,

line index, and the superelevation index.

Using a linear stepwise regression analysis, track degradation models

were developed for each of the five selected TQI's to describe the

relationship between TQI's and physical parameters in the following

form:

TQI79 = f (TQI78, C-j (independent physical parameters )-,•

)

83
GOOD

+

TQI = 0.2 INCH

DISTANCE ALONG TRACK

Figure 1. Concept of a Track Quality Iridex (TQI)

84
XHQNi Ainvnb )l3Vyi

85
TABLE 2

SELECTED TQI's

Vari abl

e

Code Name Unit Final

Choice

yi GAMN Mean Gage Inch

GASD Standard Deviation of Gage Inch X

^3 GA99 99-Percentile Gage Inch X

74 GA3M Third Moment of Gage (Inch)3/1000

GA4M Fourth Moment of Gage (Inch)VlOOO

ye XLDV Standard Deviation of

Cross-level

Inch

y? WASD Standard Deviation of Warp Inch X

^8 WA99 99-Percentile of Warp Inch

yg PRSD Standard Deviation of

Profile Space Curve

Inch

yio PRSM Standard Deviation of

Short MCO of Profile

Inch/lOOO

yii PR99 99-Percentile of Intermediate MCO of Profile

Inch

yi ? ALSO Standard Deviation of

Alinement Space Curve

Inch

yi3 ALSM Standard Deviation of

Short MCO of Alinement

Inch/lOOO X

yi4 BSEL RMS Value of Cross-level

Deviation from Balanced

Superelevation

Inch X

86
where Ci are constants associated with each independent variable.

Separate sets of equations were derived for each distinct level of

maintenance. Table 3 lists the predictive equations for the final five

TQI's for unmaintained track. The coefficients of determination (r2)

for all TQI's were well above 0.8. (The previous value of the TQI was

the most significant parameter in predicting the future TQI.) This

completed the first phase of this study.

Figure 3 illustrates how the prediction equations can be used in track

maintenance planning. In this example, the surface condition of seven miles of welded track section is projected, using the surface index

TQI prediction equation. The solid circles indicate the measured data

points in 1978 and 1979. The open circles indicate the track condition

projected by the TQI equation. Note that the measured condition of

track in 1979 is lower (better) than the projected condition. This

section of the track received discretionary surface operation during

1978 and 1979, and the dashed line represents the effect of the surface

operation. The annual tonnage on this section of track was 7 MGT

during the study period. At that time the annual tonnage was estimated

as 10 MGT for 1980 and 15 MGT for 1981. Track condition was then

projected using these tonnage values for 1980 and 1981. If no maintenance is performed, this track section is estimated to be within the

standards for Class 3 in 1981.

Fiscal Year 1981 Research ' . '

After completion of the Phase I study, the following three activities

were undertaken in Phase II of the FRA-Conrail cooperative research

program.

(1) The 1978-1979 TQI's and the prediction equations of the

Phase I program were analyzed for validation with 1980 data.

(3) An FRA T6 track geometry survey was conducted in July

and August 1980 over the Lehigh Division test zone, which

contained 124 unmaintained track segments. Track geometry

data were than processed into five TQI's, and physical

parameters were quantified for the 1979-1980 period. Results

showed that the equations derived from 1978-1979 data did not

predict the 1980 TQI values, except for the surface index TQI.

This validation study was based on a somewhat different and

smaller test zone than the zone used in the Phase I study.

This study used a test zone with less traffic, more curves,

and predominantly continuous welded rail. It was recommended

that these prediction equations could be improved by adding

new physical parameters and extending the study period used

to develop such equations.

The study also found that segment length affects the accuracy

of the prediction equations. Shorter track segments of less

87
TABLE 3

PREDICTION EQUATIONS FOR

UNMAINTAINED TRACK

TQI rreaiction equation^ K

Gage

Roughness y2 = -0.036 + 0.84y2 + 0.0007x2

+ 0.0008x3

0.89

Wide Gage

Index y3 = 13.88 + 0.75y3 + 0.003xi

+ 0.0116x4 + 0.0526x5

. 0.85

Surface

Index

yy = -0.004 + 0.92y7 + 0.0037xi

-0.0032x4 + 0.069xg + 0.0005x7

+ 0.029X8

0.90

Line Index

A

yi3 = 3.84 + 0.71yi3 0-^29xi

+ 0.349x4 + 6.57x5 + 3.18x3

0.83

Superelevation Index yi4 = 0.043 + 0.94yi4 + O.OI2X4

+ 0.0009x7

0.97

*In this table yi is the previous value of a TQI; xi is the tonnage,

X2 is the percent heavy wheels, X3 is the speed, ^4 is the curvature,

X5 is the raiT type (0 for welded, 1 for bolted), X7 is the percent

bent rail, xg is ballast level 1 (mildly dirty) and xg is ballast

level 2 (pumping).

88
89
than one-half mile had more prediction error than lonjier

segments.

(2) A small, independent study was conducted to determine the

relationship between track geometry and the critical vehicle

responses likely to cause derailment. In the course of their

movement along the track, all vehicles respond to geometric

irregularities in the track. Some of these irregularities may

cause the vehicles to attain motions that are critical -- primarily to safe operation, secondarily to lading damage or

ride di scomfort--and their amplitudes must be reduced through

subsequent maintenance. The objective was to identify those

geometry perturbations that (by causing critical motions to occur within a vehicle type of configuration, or within the

scope of operations allowed on the track) produce an unacceptably high probability of derailment (lading damage

or ride discomfort) on the track. Initial findings of this

study present methods of processing loaded track geometry

measurements by using filters and thresholds that are adjusted

to effect a low probability of derailment for the vehicle

types, configurations, and operations found on a given track.

The performance-based descriptors that are being developed

have a uniform threshold with a wavelength response characteristic that varies continuously and linearly with track speed.

It is possible, according to the study that unnecessarily long

wavelength track maintenance is being undertaken by railroads

without affecting geometry uniformity at shorter wavelengths--

where derailment mechanisms are at work.

(3) The final, major activity of Phase II encompassed the other

two activities and is still continuing. In this study, the

approach and methods used in the Phase I and Phase II were

reviewed. Extensive evaluations of track deterioration

modeling and track maintenance planning were undertaken.

Also, there was an attempted engineering analytical corroboration of the statistical results regarding the mechanism of

track deterioration developed during Phase I. Ultimately,

the Phase II plan is expected to formulate an analytical model

of track deterioration that should lead to an optimal track

maintenance program which can be practically implemented on

an operating railroad.

Preliminary results from the Phase II study activity are summarized

bel ow.

(1) The TQI's were suggested based on a space curve of alignment,

profile and crosslevel, filtered to minimize the impact of

wavelengths below 5 feet and above 50 feet. This is because

vehicles respond to track irregularities between these wave90
lengths, and thus the TQI's are directly related to the two

major track functional parameters (accident risk and ride

quality). The TQI's statistical measures should be the

standard deviation and 95th percentile because both cyclic

and extreme irregularities influence vehicle behavior and are reasonably represented by standard deviation and 95th

percentile

.

(2) Segmentation of track for analysis and planning is reconmended

on hal f-mileposts and at the beginning and end of curves.

(3) Two approximate engineering formulas give the track permanent

response to the vehicle track force: one for vertical

deterioration (related to profile and crosslevel TQI's) and

one for lateral deterioration (related to gage and alignment

TQI's). Sensitivity analyses were performed on these formulas

to determine which of the independent causal variables had the

most influence on track deterioration for mixed freight

traffic. The strong factors for vertical deterioration were

previous TQI, track type (jointed or welded), vehicle type,

especially the ratio of truck center distance to rail length,

speed, ballast type, and condition and drainage condition.

Tie type and rail inertia had little influence, mainly because

of the consistency of these parameters in the test zone. The

sensitivity results were similar for the lateral deterioration

because of the coupling of vehicle response to lateral and

crosslevel irregularities.

(4) Comparing the results of the engineering analysis with the

Phase I TQI deterioration equations was unsuccessful because:

Phase I equations were the result of the linear stepwise

regression analysis, while the actual engineering relationships are combined multiple parameters; and Phase I TQI

equations are too stongly dependent on previous TQI and thereby distort the dependence on the other terms.

(5) In the review of the physical parameters, the recommendations

were to delete the surface bent rail as it cannot be visually

assessed reliably and to add ballast type, rail age, and time

since previous descretionary maintenance.

(6) A standard statistical computer software package should be

utilized for calculating TQI's and deriving track deterioration equations.

(7) Regression models should be developed to predict change in TQI as a function of previous TQI and the independent variables

(track type, traffic, etc.). Non-linear multiplication type

regression models should be investigated. This should improve

the ability to predict future track deterioration.

91
Early in 1982, this study activity is to be completed with the development of a detailed Phase III plan.

Remaining Research and Conclusions

With the collection of track geometry, track structure, maintenance and

traffic data, research is continuing at FRA to develop a change in TQI

prediction equations utilizing the extensive track maintenance data

base started with Conrail in 1978. To help obtain a more significant

statistical data base, the Conrail test zone has been expanded to 360

miles; 90 miles of the Amtrak Northeast Corridor (NEC) has also been

added to this study. The Amtrak (NEC) data base contains concrete, as well as wood, ties subject to a variety of operating conditions.

Resulting FRA research will assist Amtrak in determining the appropriate

track surfacing cycle.

In conclusion, this research program' expects to accomplish the following.

(1) Develop TQI's from track geometry data that relates to track

safety and performance requirements.

(2) Establish degradation prediction equations based on change in

TQI's with respect to traffic, track structure, and maintenance data

.

(3) Develop an analytical basis for determining appropriate maintenance cycles to insure safe track condi tions--thus completing

Phase III of the study.

References

1. ENSCO, Inc., "Use of Automatically Acquired Track Geometry Data

for Maintenance-of-Way Planning," Report No. FRA/0R&D-80/44,

U.S. Department of Transportation, Federal Railroad Administration, Washington, DC, June 1980.

2. ENSCO, Inc., "A Prototype Maintenance-of-Way Planning System,"

Report No. FRA/ORD-80/47 . I , U.S. Department of Transportation,

Federal Railroad Administration, Washington DC, November 1980.

3. ENSCO, Inc., "A Prototype Maintenance-of-Way Planning System,

Volume IV Validation of the Prototype MOW Planning System,"

Report No. FRA/ORD-80/47 .IV, U.S. Department of Transportation,

Federal Railroad Administration, Washington, DC, October 1981.

92
ANALYTICAL INVESTIGATION OF LADING

RESPONSES FROM VARIOUS PULSE SHAPES

W. P. Manos

Consultant to Association of American Railroads

Chicago, Illinois 60616

J . C . Shang

G.A.R.D. , Inc

.

Niles, Illinois 60648

J. B. Raidt

Association of American Railroads

Chicago, Illinois 60616

Abstract: The dynamic response of lading and the maximum

end-wall forces from variously shaped input pulses in a struck railroad freight car were analyzed. Five different

pulse shapes: rectangular, three triangular, and a half

sine wave were investigated for cases where the coulomb

friction between the lading and the car floor, and the

lading looseness, i.e., backlash, were considered. Equal

impulses, of magnitude: I = /^t ^^F^^ ( t) dt , were chosen as the

comparison criteria.

The maximum lading response and the maximum end-wall forces

from the lading to various pulse shapes were compared using

both compressive force and period ratios. The investigation

did not intend to find any optimum car cushioning characteristics, but attempted to show the effects of floor friction

and lading looseness on the maximum end-wall forces for each

input pulse shape, when plotted as a function of lading

stiffness. The results showed that rectangular pulse shapes

do not always produce the lowest maximum end-wall forces for

all conditions of lading stiffness, lading looseness and

floor friction.

The results for the non-dimensional, maximum lading forces

from rectangular input pulses, as a function of period ratio

were shown to compare very well with those obtained using

the phase plane delta method. For the other input pulses,

the computer solutions were compared with the analytical

solutions for zero floor friction and lading looseness.

93
Key words: End-wall Forces; Impulse Input Wave Forms;

Lading Dynamics; Lading Flexibility and Looseness with

Floor Friction;

1.0 INTRODUCTION

From the instant a freight car departs from the loading

platform until it reaches its destination, it is constantly

subjected to many dynamic conditions which arise from

railroad environmental disturbances, such as rough starts

and stops, and impacts in switching yards. The latter

situation creates relatively large shocks in cars and the

associated lading, and it is necessary to provide the

proper cushioning devices between adjacent cars, so that the

lading may arrive at its destination in a relatively damage

free condition. When hydraulic devices are used for cushioning impact forces, they can be designed to obtain a wide

variety of force/travel characteristics. It is certainly

incumbent upon the designer to select a force/travel

characteristic that minimizes the maximum end-wall forces,

caused by the shifting of the lading. Minimizing the

maximum end-wall forces is commonly referred to as the "Min.

Max. Problem.

It has been thought that a constant force/travel or force/

time characteristic produced the minimum-maximum lading

end-wall force. In this Report, it is shown that a

constant force/time pulse does not always produce the

minimum maximum dynamic response for all conditions of

lading flexibility. In fact, certain combinations of delta

functions and step functions can produce even lower

responses than those shown [g ]t however, they would be

extremely difficult to achieve for all combinations of

impact velocity, lading flexibility, floor friction, and

lading slack or looseness.

* The number in brackets [ ] refer to the references listed

in Section 5,0 of this Report.

94
2 . 0 PROBLEM STATEMENT

The problem to be analyzed in this paper consists of a

striking car of mass, M , traveling with an initial velocity,

V , and impacting a loaded car, initially at rest, through a hydraulic cushioning device. It is the object of this

analysis to explore the effects that various impacting pulse

shapes have on the maximum lading end-wall forces or maximum

dynamic load factors. The dynamic load factors of various

pulse shapes, other than the one with a constant characteristic, will be compared. This analysis considers as

parameters non-dimensional variables , involving lading

flexibility, lading looseness and floor friction. Comparisons of the maximum non-dimensional end-wall forces are made

for five selected positive pulse shapes, based on equal

values of mean impulsive force over the same time of

application.

3.0 ANALYSIS

This analysis is based on the following assumptions:

(1) The lumped parameter system shown in Figure 1 is valid.

(2) The lading flexibility is linear.

(3) Coulomb friction exists between the lading and the car

floor.

The schematic presentation of the system under consideration

is shown in Figure 1. The meaning of the symbols in Figure

1 may be found by referring to the mathematical nomenclature^

listed in Table 1.

3.1 Basic Equations

When a stationary car, M^, is struck by a moving car, Mg, at

an impacting velocity, V , through a hydraulic buffer,

F^, the lading, M^, in tRe struck car, having a flexibility,

k, starts to slide through a distance, a, against coulomb

friction, y , before coming into contact with the end-wall of

the struck car. It then begins to compress against the endwall, thereby producing pressure between the end-wall and

itself. This is called the end-wall or lading force, F^.

Since friction, which in this case is assumed to be coulombic, always opposes the motion, it appears in the

equations with a sign opposite to that of the velocity.

95
Table 1. Mathematical Nomenclature

a = Black lash between lading and end-wall

Fb = Hydraulic cushion force

Fo = Average cushion force

k = Lading flexibility

Mg = Struck car mass

= Lading mass

M = Striking car mass

s M ,M BS BL= Equivalent masses, as defined by Equation Set (6)

n = Force application period - natural period ratio

p = 2Trn

T = Natural period of the system

t = Time

t-j^ = Time duration of load application

Vq = Impact velocity

XXX 1' 2' 3 = Displacements of striking car, struck car and

lading, respectively

yl,y2 = Relative displacements, defined by Equation Set

(6)

' s = as defined by Equation Set (10)

3 = Friction force - average applied force ratio, as

defined by Equation Sets (10)

T = Dimensionless tirae, as defined in Equation Set

(10)

T = Dimensionless time required for lading to travel

a distance of 'a'

f(T) = Normalized cushion force, as defined by Equation

Set (10)

y = Friction coefficient between lading and car

floor

^ = z - z = Maximum end-wall force dynamic load

factors

F = End-wall force

V

With reference to Figure 1, Newton's laws of motion, and the

preceding considerations, the two sets of equations shown as

(1) and (2) are obtained. Eqs. (1) are valid when the

lading is not in contact with the wall, and Eqs. (2) are

applicable when the lading is in contact with the wall

[1,3,5 ],

96
si b

b B 7-3 r—r li

i-i Li J

for x^ x^< a

and X2 -x^ 7^ 0

(1)

1^2 -SI

and

M k\ = -F^ si b

^b = \^2 + (^2-^3^ —' ' 5" X2-X3I

yM^ g = k l^x^

- (x^+a)

[

yM^. g +k I x„ - (x-.+a)

The initial conditions are:

]

= M x^

For x^ -X-, > 2 3 ~ a

and X2 -x^ 7^ 0

(2)

x^(0) X2(0) = X3 (0) = 0

(3) x^(0) = V^; X2 (0) = X3 (0) = 0

Application of the following transformations to equations

(1) and (2):

^2 ^2 ^3'M

BS

1

M

1 +

1

M.

BL

They become:

M.BS

y2 "lI

(4)

•y'2 = - B

and : yl -

y2 +

y2 M

yg

BL

F,

for y2^ a

and y^T^ 0 (5)

M. y2 = - B

b y2 ^

B

M, y2 = BL M,

_b _ y2 M

B |y2|

yg + M

M. BL

BL

for y2^ a and y27^ 0 (6)

J

97
The corresponding initial conditions are:

Y^(0) = y2(0) = Y^iO) = 0

^l^^^ = ^o (7)

By assuming a cushion force-time relationship, it is evident

from the second equation in Eqs. (6) that it becomes

uncoupled from the first equation; hence, it can be solved

separately. The first equation, however, depends upon the

solution of the second equation. In order to facilitate

the solutions of the second equations and increase their

domain of applicability, it is convenient to non- dimensionalize them by the introduction of the following transformations and definitions:

Application of Eqs. (8) into the second equations in Eqs.

(5) and (6), and recognizing thatj d_^dTd_^l_d_^ , dt dt dT t, dT

and

:

d!_

dt2 .-2 ,2 t-^ di

yields:

2 —d z .2 2 r- , \ X- = 4tt n f (t)

dt^

dz

dr

dz

dT

47T n 3 B , M

BL

for dz^

dT

z

(9)

7^ 0

(10) — s

and

:

-47T ^22,n (z-z ,,.22 ) + 47T n

s f(T) - dz

dr

dz

dT

The initial conditions become

z (0) = z (0) = 0.

M.B

M.BL

(11)

for/dz 7^ 0

dT

(12)

98
3 . 2 Cushion Force-Time Characteristics [1]

In general, the cushion force, F^^, is a function of y2and

which, in turn, are functions of time. Since this functional

relationship is determined by the cushioning unit's metering

pin design, the approach used herein is to assume various

cushion force-time relationships, with the same impulse

period of application and mean impulse force, to calculate

the maximum end-wall force and then determine the

cushion force-travel characteristic.

When impact tests are performed, the measured quantities

are cushion force vs. time and displacement vs. time; hence,

force-travel characteristics can be developed from this

information. The maximum end-wall forces for five forcetime relationships were calculated, and these relationships

are shown in Figure 2.

With reference to Figure 2, the equations for the various

selected cushion force-time relations are given [1,4] by:

curve 1: f(T)=u(T)-u(T-l) (13)

curve 2: f(T) = -2(t-1) [u(t) -u(t-1)J (14)

or

f(T) = 2 C-tu(t) + u(t) + (t-l)^u(t-lj] ^ curve 3: f(T) = 4t[^u(t) -u(t-,5)J -4 (t-1) ^ u ( t- . 5

)

-u ( T-y

or: ^ (15)

f(T) - 4 Itu(t) -2(t-.5) u(t-.5) + (t-1) u(t-1)J

curve 4: f(T)=2Tj^u(T)-u(T-l|3

or: f(T) = 2 Qi(t)t - (t-1) u(t-1) -u(t-1)J . (16)

curve 5: f(T) = it sinTTT fu(T) -u(t-1)1

2

or: f(T) = T[ru(T) sinuT + u(t-1) sin 7t(t-1)J (17)

2

where:

u(t) is the unit step function, defined as:

u(t) = 0 for T< 0 (18)

u(t) = 1 for T> 0

99
3.3 Solutions and Results

For the five force-time relationships shown in Figure 2,

analytical solutions for the non-dimensional end-wall forces

were obtained for zero friction and lading looseness, using

Laplace transform techniques [1,4]. Details of the analytical

procedure are shown in Appendix A. The maximum end-wall force

or dynamic end-wall load factors are compared for each loading

case, as functions of lading stiffness, in Figure 3. Note the

the rectangular input pulse does not always produce the lowest

dynamic load factor for all conditions of lading rigidity;

however, it appears to be the best compromise for the. higher

floor friction and the more flexible lading conditions.

In Appendix B the phase plane-delta method [2,3] was applied

to the Case 1 forcing function, and a very simple equation

was derived for the maximum end-wall force, for all conditions

of lading looseness and floor friction. Although this method

can be applied discretely to the other loading conditions, a considerable amount of work would be required for each case of

lading stiffness, lading looseness, and floor friction; hence a computer program was developed to solve the maximum lading

response for all the cushion forces, lading looseness, and floo.r

friction cases. The computer program logistics and .flow

diagrams are presented in Appendix C, and the diagrams showing

maximum non-dimensional end-wall forces versus lading stiffness

or period ratio are shown in Figures C2 through C31. For each

load":ng case, a family of curves vras generated for six values

of floor friction and for six values of lading looseness.

The computer results, and the analytical and phase plane

results were coincident for those cases solved by the latter

two methods.

3.4 Discussion of Results

It is apparent from Figures C2 through C31 that the maximum

end-wall force increases as backlash or lading looseness

increases, and decreases with increasing floor friction. These

results are expected, since increased lading looseness permits

the lading to strike the end-wall v;ith an initial velocity,

whereas increasing the floor friction removes impact energy

prior to and during the lading compression at the end-wall.

In "general, when impact testing is performed, various forces

are measured as functions of time. In particular, cushion

and end-wall forces versus time are measured with load cells,

but cushion travel and impact velocity are recorded as functions

of time using displacement transducers. From these data,

impulse - change-in-momentum checks and cushion force - travel

characteristics can be developed for each impact velocity and

mass condition.

In order to utilize the non-dimensional maximum lading force

curves, it is necessary to know the masses of the lading,

struck car body and striking car, as v;ell as the lading flexibility and looseness, and the floor friction. The mean impulsive

force can be determined from the momentum change for each impact

velocity, and the cushion closure can be approximated from the

momentum equations for each stroke and impact velocity, assuming

an inelastic impact. Depending on the shape of the force-time

curve, which depends upon the cushion characteristics, the

maximum end-wall force can be estimated from the appropriate
4.0 CONCLUSIONS

The purpose of the study was to explore the effects that the

shape of the force-time relationships has upon the maximum

lading end-wall force. Based on the results, the following

conclusions can be made:

1. Within certain small values of n, i.e., "soft lading,"

the shapes of the input pulses were of relatively small

significance in determining the magnitudes of the maximum lading end-wall forces.

2. Among the five input pulse shapes investigated, the triangular impulse (Curve 2 in Figure 2) always produced the

highest maximum end-wall forces, when the same values of

n above the minimum n and 3 were considered.

3. In general, the maximum lading end-wall force increased

as the lading looseness increased, and it decreased as

the friction increased, for all of the cases considered

(See Figures C2 through C31)

.

4. The trend of the results remained practically the same,

except for changes in the magnitude of the maximum endwall forces, when friction and lading looseness were

taken into account.

5. The rectangular pulse shape produced lower end-wall

forces, for intermediate values of lading flexibility,

and for all values of lading flexibility with large

values of floor friction. Cartoned canned goods fall

into this range.

6. Pulse shape 3, 4, and 5 in Figure 2 produced lower endwall forces than the rectangular pulse, for the more

rigid ladings at all values of lading looseness and the

lower values of floor friction. Tin plate and lumber,

etc. , would be lading types that fall into this category.

In general, this analysis showed that the constant forcetime pulse does not always yield the minimum-maximum lading

end-wall force conditions, for all values of lading flexibility, floor friction, and backlash; however, for the most

practical - overall conditions, the rectangular pulse represents the best compromise.

5.0 REFERENCES

1. Manos, W. P., and Sang, J. C. , "Analytical Investigation

of the Dynamic Response of Lading to Various Cushion

Pulse Shapes," Pullman-Standard, Unpublished Data, 1965.

2. Jacobsen, L. S. , "On a General Method of Solving Second

Order Differential Equations by Phase-Plane Displacements," ASME Paper No. 52-A-l, 1952.

3. Den Hartog, J. P., "Forced Vibrations with Combined

Coulomb and Viscous Friction," APM - 53 - 9, 1953.

4. Thompson, W. T., Theory of Vibration with Applications , Prentice-Hall, Inc., Englewood Cliffs, New Jersey, 1972.

101
5. Timoshenko, S., Young, D. H. , and Weaver, W. , Vibration

Problems in Engineering , John Wiley and Sons, New York,

New York. Fourth Edition, 1974.

6. Sevin, E. , "Min-Max Response of a Single D.O.F. System,"

ASME Transactions, 1956.

6 . 1 Appendix A

Analytical Solutions Using the

Laplace Transform Method

The forcing functions, f(T), given by Equations (15) through

(19) , were used to facilitate the application of the Laplace

transform method for obtaining the simpler solutions. This

method is applied to the special case of each force characteristic curve, when neither floor friction nor lading looseness are considered. 6.1.1 Case No. 1: Rectangular Pulse

Input.

This case assumes Curve 1 of Figure 2, with z = 3 = 0 , or

a = y = 0, i.e., no backlash or floor friction. Combining

Eqs. (13) and (11) gives:

2 ^ + 4^^n^z = 4TT^n^ t^^^ -u(t-1)J ; (19)

di

Transforming and rearranging (21) , using the initial condition ( 14 ) , yields

:

zwhere: s is the Laplace tranform variable, and the bar over

the variable z denotes the Laplace transformation of the

variable z(t). Inversion of the above equation back to the

time domain gives:

z(t) = (l-cos2'^nT) u(t) - L l-cos2^n ( i-l

)J u(t-1) (b)

Eq. (b) can be interpreted as

z(t) = l-cos2''^nT, for 0 £ t £ 1 (c)

and

:

z(t) = 2sin7Tn sinirn ( 2t-1) , for t >^ 1 (d)

The maximum value of z for t £ 1 and x >^ 1 is given,

respectively, by:

z =2 for T < 1 , n

max — —2

and

:

z 2sin7Tn for x > 1 , n < /or>\ max = — — 2 (20)

102
6.1.2 Case No. 2: Rapid-Rise Traiangular Pulse Input

Friction and Backlash are zero, and the forcing function for

this case is given by Eq. (17) . The governing equation

becomes

:

^2^ ^ 8^2^2 f-tu(T) +u(T) +(T-1) ^(T-1)J

ansform i

Is 2

L s

d z , . 2

7y + 4Tr whose transform is

z (s) = 2 >r

(21)

2_,. 2 2 s +4iT n 2^, 2 2

s +47T n

2^. 2 2 s +4tt n Its inversion is

z(t) =2 4 r 1-T+ 1 sin27TnT -cos27TnT7 u(t) +[(1-1) - 1 sin 2Tin(T-l)J u(t-12^

2iTn

(b)

(c)

which is interpreted as:

z(t) =2(1-t + 1 sin 27Tm: -cos27TnT), for 0 ^ t _< I 2T7n and : r H

z(t) = /— (l-cos2Trn) sin27rnT + |^in27Tn-2-rTnJ cos2TTnT ) , for T > 1 (d)

The maximum value for t <^ 1, and t >^ 1 is given, respectively, as follows:

= 2 r2 - 1

follows: C

p - ^ J

I 2TTn \OT

i

_1 4TTn sin -.2 2 , , 47r n +1 for T<1, n >.371

L

cos

-1

4Tr^n^ + l

max

and:

z = Tvn U 2, for t>^1, n< . 371

which is the same as that of CASE 4 expressed in Eq . (26T.

The maximum values for these cases are shown as functions of

n and compared with one another in Figure Al

.

^ [2 (l-cos27Tn) +4iTn (TTn-sin2TTn)'] \

5.1.3 Case No. 3: SymmetricalTriangular Pulse Input

Friction and backlash are zero, and the forcing function is

given by Eq. (14) . The equation to be solved for in this

case is: —» + 4iT n z

6.\

i.V -[4 [

tu(t) -2{a-.5) u(T-.5)

u(T-l)jJ

(T-1)

(23)

The Laplace transform of Eq. (25) , after some rearranging,

becomes

:

z(s) Ls^- 2^. 2 2 /

' s +4Tr n ^

, „ -.5s, -s. l-2e +e ) (a)

Inversion of Eq. (a) gives:

z(T) = 4^(7- 2^ sin 2TTnT_^ u(t) -2 Q-.5 - 2^ sin 2iTn(T-.5)J

u(T-.5) + [j-1 - sin 2TTn (t-1)J^ u(t-1)J. (b)

103
which is reducible to:

z (t) = 4 (x- 2^ sin 2TrnT) , for 0<t<^ .5 (c)

t) = 4 2^ [F""-^ 2TTnT - 2sin 2Trn (t- . 5)^^^

4 /jt z(t) = —(l-cos7rn) simTn(2T-l), for t>^1 - (e)

The maximum value is:

2=4

max —(l-cos7Tn) , for t_>1 (24)

6.1,4 Case No, 4: Slow-Rise Triangular Pulse Input

Friction and backlash are zero, and the forcing function is

given by Eq, (16), The equation to be solved becomes:

d z dT

It transforms to;

+ 4Tr^n^z = STT^n^ [ lUd) - (x-l) ' u(t-1)J (25)

2(s) = sj[j2- e'^r (a)

J1(i-e-^)~U - ^ 1

L s+4TTn-' t- s+4Trn-J

Inversion of Eq, (a) back to the time dpmain gives:

z(t> = 2 i^fr- sin 2TTnTl u(t) - fr- — sin 27Tn(T-l)

ij- 2/Tn ^ —' 2 Tin - cos 27rn(T-l)_7 u(t-1)^ (b)

which is interpreted as:

z(t) = 2 Ct- 2^ sin27TnT"^, for 0^t_< 1 (c)

and

:

^^''^ = ^|0'°^2un"""^ si"2Trn

J

5in2TTnT - [^^2nn" " cos27TnJ

cos2T7nT^ for t>^1 (d)

The maximum value of z always occurs in the residual amplitude,

that is:

^ "^m^x = ^ ^2 (l-cos2Trn) +4TTn (un-sin2Trn)Jj' ^26)

104
6.1.5 CaS'B No. 5: Half Sine Wave Pulse Input

Friction and backlash are zero, and the forcing function is

given by Eq. (15). The equation to be solved for this

case becomes:

2 —d z . .2 2 .2 5" + 4Tr n z = 471 dT^ [?] i:u(T siniTT + u(t:-1) sinu

The equation transforms to:

-.2 2 ~ ( \ -

^ z(S)

2 I 2 2 2 2 2 4n -1 |_s +Tr s +4Tr n Its inversion gives

2iTn' Z{T)

2n

TT n P 1

n^-l [_s^

ion giv

(1+e

-s)

SinTTT- 2n sin27rnTj u(t) + ^inird-l)

sin 2Trn(T-l)7 u{t-1)>

Which is interpreted as;

2Trn^ 1 z(t) = —2—^^''•"^"^~2n~ sin2iTnT) , for 0£T£l

and:

z(T)

4n -1

2TTn 4n^-l

cosun sinirn (2t-1) , for t>1

The maximum value for t>^1 is given by

27rn_

COSTTn

1

"niax . 2 , 4n -1

and for 0 <!_< 1, n > 2" srid i, an integer;

max

where

0 <

trn 4n^-l

2n sm 2TTi

2n+l sm 4Trni2n+l0

2i

< 1

(T -0

(a)

(b)

(c)

(d)

(28)

(28a) 2n-l

The maximum-maximum end-wall force for the five selected pulse

shapes, when floor friction and backlash were present, were

obtained by solving the differential equations of motion.

Equations (10), (11) and (12), on the AAR's Dec 2050 computer

system. Details of the logic, in the form of flow diagrams,

as well as a brief description of the numerical algorithm

used to solve the equations, are shown in Appendix C.

(27)

105
106
6 . 2 Appendix B

Phase Plane Delta Method for a Rectangular Pulse

The utilization of this technique requires that C be plotted

versus — . Before using the phase plane method, the free

sliding lading equations are solved to produce the initial

conditions for this method. Kence: , ~

' /

'i =4Tr^n^ (1-3) , for • : (1)

The initial conditions are:

C (0) = -Zg - (2)

k(0) = 0

Integrating (1) using (2) gives:

t=4TT2n^(l-B)T (3)

^=4tiV(1-6) J

(4')' The final condition for (4) requires that ^ (x ) = 0, v;here

Tg is the time that the lading contacts the end-wall. Therefore:

4Tr^n^ (1-6) ^s^

s - 2^n <1

,The final velocity is obtained by substituting (5) into (3)

,

hence: ,—

i C^s) = \/ 2z^(l-6) (6)

2Trn ^

E, C^s) = 0 and (6) are the initial conditions for the phase plane

method. Figure Bl shows the phase plane scheme, in which

tan ^2TTnT

s

107
•e-^* ton » ton-' ZVn r.

2Tn(l- T«)

^22,(1.^)

f(T)

1 -t-iFigure Bl. Example of the Phase Plane Delta Method.

The maximtiin value of C for small values of n {n<H) is equal to

T2-B' For large values of n, the maximum C occurs in the first

cycle for t<1.

(6)

(7)

(8)

For this case: 5max - ri+1-6

But: r^ » ^(1-8)^+22, (1-6)

Substituting (7) into (6) gives:

^max - ^a-0)2+2z,(l-S) +1-6, n»i

For n<H, Cmax - '2-6 , or

^max - {rj^2+i„2rj cos Qirnd-Tg) +63]]) -6

5max- ( (1-6) (l-6+223)+l-2 ^(1-6) (l-6+2Zg)cos [[2iin(l-Ts)+eg]]) -6

Equation (9) holds for;

2Trn(l-Tg) + t«m-^2irnT8liT (10)

Table Bl gives values of Cmax ^or n>0.5 and various values

of 0 and Zg, which were obtained from Equation (8).

Tables B2 through B6 give values of Cmax n<^0.5, and various

values of 6 and Zg.

108
Table Bl

max for n >0. 5 versus 3 and Z s 'X 0. 0 0. 2 0.4 0.6 0.8 1. 0

0. 0 2

.

000 1. 600 1.200 0. 800 0 .400 0

.

0

0.2 2. 183 1. 780 1.375 0. 966 0. 546 0

.

0

0.4 2. 342 1. 930 1.517 1. 092 0.647 0. 0

0. 6 2

.

483 2

.

065 1.640 1.200 0 .729 0

.

0

0. 8 2. 612 2

.

186 1.750 1. 290 0.800 0

.

0

1.0 2. 732 2

.

300 1.850 1. 380 0.863 0. 0

Table B2

max for n = 0. 1 versus 6 and Z s 0. 0 0. 2 0.4 0.6 0.8 1. 0

0.0 0. 618 0. 388 0.224 0.116 0.046 0. 0

0.2 0. 628 0. 325 0.088 0.0 0.0 0. 0

0.4 0. 632 0. 256 0.0 0.0 0.0 0. 0

0.6 0. 654 0. 219 0.0 0.0 0.0 0. 0

0.8 0. 698 0. 234 0.0 0.0 0.0 0. 0

1.0 0. 765 0. 301 0.0 0.0 0.0 0. 0

Table B3

max for n = 0.2 versus 3 and Z

0. 0 0. 2 0. 4 0. 6 0.

s

8 1. 0

0.0 1. 176 0. 870 0. 595 0. 355 0. 157 0. 0

0.2 1. 231 0. 889 0. 565 0. 266 0. 0 0. 0

0.4 1. 250 0. 867 0. 487 0. 116 0. 0 0. 0

0.6 1. 256 0. 831 0. 393 0. 0 0. 0 0. 0

0.8 1. 257 0. 792 0. 296 0. 0 0. 0 0. 0

1.0 1. 257 0. 756 0. 207 0. 0 0. 0 0. 0

Table B4

max for n = 0.3 versus 3 and Z s X 0. 0 0. 2 0.4 0.6 0.8 1. 0

0.0 1. 618 1. 261 0.916 0.586 0. 279 0. 0

0.2 1. 725 1. 347 0.971 0.597 0. 210 0. 0

0.4 1. 789 1. 383 0.968 0.531 0.043 0. 0

0.6 1. 830 1. 393 0. 934 0.430 0.0 0. 0

0.8 1. 855 1. 388 0.883 0. 306 0.0 0. 0

1.0 1. 871 1. 372 0.821 0.170 0.0 0. 0

109
Table B5

max for n = 0.4 versus 3 and Z s\ 0. 0 0. 2 0. 4 0. 6 0.

s

8 1. 0

0.0 1. 902 1. 513 1. 127 0. 744 0. 368 0. 0

0.2 2. 053 1. 653 1. 250 0. 840 0. 401 0. 0

0.4 2. 164 1. 746 1. 315 0. 857 0. 316 0. 0

0.6 2. 250 1. 809 1. 345 0. 831 0. 171 0. 0

0.8 2. 316 1. 851 1. 351 0. 774 0. 0 0. 0

1.0 2. 369 1. 878 1. 339 0. 696 0. 0 0. 0

Table B6

max for n = 0.5 versus 3 and Z

>^ 0. 0 0. 2 0. 4 0. 6 0.

s

8 1. 0

0.0 2. 000 1. 600 1. 200 0. 800 0. 400 0. 0

0.2 2. 182 1. 778 1. 371 0. 957 0. 520 0. 0

0.4 2. 334 1. 919 1. 495 1. 050 0. 527 0. 0

0.6 2. 462 2. 033 1. 586 1. 097 0. 464 0. 0

0.8 2. 572 2. 125 1. 650 1. 109 0. 352 0. 0

1.0 2. 666 2. 199 1. 692 1. 095 0. 207 0. 0

no
6.3 Appendix C

Computer Solution of Equations for

Hon- Zero Ladlng-Ploor Friction

and Backlash

6.3.1 DescrIptlon

The computer program determines the dynamic response of the

lading In the struck freight car to the five different Input pulse

shapes sho%m belowi

Case No. 1: Rectangular Case Mo. 2t Rapid-Rise Case No. 3:SyinmetrlThe program uses a Modified Buler numerical Integration

routine. In determining the maximum load factors for the lading

response, for a time simulation period of five soconds. The results

show the effect of varying the floor's friction coefficient and the

force application perlodoto-natural period ratio.

Ill
6.3.2 Data Flowcharts

Figures CI a and b show the data flowcharts for the computer

solution of equations, involving non-zero lading floor friction

and lading backlash.

Figure Clc shows a more detailed data flowchart for the calculations involving coulombic floor friction.

6.3.3 Input Data

The Following data is needed for input to the computer program:

TP Time Period for Simulation

TI Time Increment for Numerical Integration

NC(J) Pulse Shape Code for Cases J=l,5

Code Value =0, if case is not used = 1, if otherwise

BJ) Floor Friction Values, J=l, 11

S(J) Backlash Values, J=l, 11

R(J) Force Application Period-to-Natural Period Ratio

Values, J=l, 20

6.3.4 Output

The following output is printed in the computer program results

K Pulse Shape Case

S(J) Backlash Value

B(J) Friction Value

R(J) Force Application Period-to-Natural Period Ratio Value

ZDM Maximum Value of Lading Response for the Simulation

Time Period

The maximum value of lading response, ZDM, is calculated for

all combinations of S(J), B(J) and R(J), for each pulse shape

case, K.

112
READ IN TIME PERIOD -TP, TIME INCREMENT TI, PULSE SHAPE CODE VALUES* NC(J)

READ IN FLOOR

FRICTION VALUES- B(J)

READ IN BACKLASH

VALUES-S(J)

READ IN FORCE APPLICATION

P E R 1 00- NATURAL PERIOD

RATIO VALUES- R(J)

1 WRITE OUT ABOVE

1 INPUT DATA 1

1 K.0 1

WRITE OUT PULSE SHAPE

CASE, BACKLASH VALUE,

FRICTION VALUE. FORCE

APPL. PERIOD- NATURAL

PERIOD RATIO, MAXIMUM

LADING RESPONSE

SET BACKLASH VALUE

S(JS)

SET FRICTION VALUE

B(JB)

SET FORCE APPL. PERIOD- NATURAL

PERIOD RATIO VAUJE

R(vlR)

SET INITIAL CONDITIONS

HALF -TIME INCREMENT

T-T+. 5TI

0

Figure Cla. Data Flowchart for the Computer Solution of

Equations for non-Zero Lading Floor Friction and Lading Backlash.

113
SET FORCE FT

ACCORDING TO PLUSE

SHAPE CASE

HALF-TIME INCREMENT

NUMERICAL INTERGRATION

VELOCITY AND DISPLACEMENT

SET NEW

MAXIMUM FOR

LADING RESPONSE

DETERMINE

FRICTION FORCE

FR (SEE«)

DETERMINE

INCREMENT

HALF-TIME

ACCELERATION

FULL-TIME INCREMENT

NUMERICAL INTEGRATION

VEUXITY AND DISPLACEMENT

YES

SET NEW

MAXIMUM FOR

LADING RESPONSE

Y

DETERMINE

FRICTION FOfCE

FR(SEE*)

DETERMINE FULL-TIME

INCREMENT ACCELERATION

©

SEE FIGURE Cic:

DETAILED DATA FLOW CHART

FOR THE COMPUTER SOLUTION

FOR EQUATIONS INVOLVING

COULOMBIC FLOOR FRICTION.

Figure Clb. Data Flowchart for the Computer Solution of

Equations for Non-Zero Lading-Floor Friction and Lading Backlash.

114
BREAKAWAY

FRICTION CODE

KB *0

INCREMENT TIME T«T+ .5«TI

DETERMINE

APPLIED FORCE

FT

Figure Clc. Detailed Data Flowchart for the Computer Solution

for Equations Involving Coulombic Floor Friction.

115
6.3.5 Case No. 1: Rectangular Pulse Input.

Figures C2 through C7 show the calculated maximum end-wall

force ratio v£. lading flexibility ratio curves, for values

of both Z and 6 = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0, respectively,

s 6.3.6 Case No. 2: Rapid-Rise Triangular Pulse Input.

Figures C8 through C13 show the calculated maximum end-wall

force ratio vs. lading flexibility ratio curves, for values

of both and 3 = 0.0, 0.2, 0.4, 0.6. 0.8 and 1.0, respectively.

6.3.7 Case No. 3: Symmetrical Triangular Pulse Input.

Figures C14 through C19 show the calculated maximum end-wall

force ratio vs. lading flexibility ratio curves, for values

of both Zg and 6 = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0, respectively

6.3.8 Case No. 4: Slow-Rise Triangular Pulse Input.

Figures C20 through C25 show the calculated maximum end-wall

force ratio vs. lading flexibility ratio curves, for values

of both Z and B = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0, respectively,

s 6.3.9 Case No. 5: Half Sine Wave Pulse Input.

Figures C26 through C31 show the calculated maximum end-wall

force ratio vs. lading flexibility ratio curves, for values

of both Z and 3 = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0, respectively.

ACKNOWLEDGEMENTS

The authors would like to acknowledge the assistance of

Dr. Robert Breese, who technically edited and checked the final

report. The authors are also indebted to Mrs. Patricia Collier,

for her accurate and neat typing of the text and many complicated

mathematical equations, and to Mr. Raymond Trubic, who prepared

some of the illustrations used in the Report.

116
Flexibility Ratio, n.

Figure C2. Case Nio. 1: Rectangular Pulse Input. Maximum EndWall Force Ratio vs. Lading Flexibility Ratio, for Zg = 0.0 and

3 = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0.

Case No. 1

Flexibility Ratio, n

Figure C3. Case No. 1: Rectangular Pulse Input. Maximum EndWall Force Ratio vs. Lading Flexibility Ratio, for Zg = 0.2 and

e = 0.0, 0.2, 0,4, 0.6, 0.8 and 1.0.

117
Case No. 1

Flexibility Ratio, n

Figure C4. Case No. 1: Rectangular Pulse Input. Maximum EndWall Force Ratio vs. Lading Flexibility Ratio, for Zg = 0.4 and

6 = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0.

X

ISE

(0

I N

o

ri

*i

<0 06

0>u

oh

I

CH

s

Case No. 1 Z-= 0.6

3^

t3 ^o.£t

Sr. C.St.

3 = u<s

f.o a..o 3.0 •sio

Flexibility Ratio, n

Figure C5. Case No. 1: Rectangular Pulse Input. Maximum EndWall Force Ratio vs. Lading Flexibility Ratio, for = 0.6 and

6 = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0.

118
Case No. 1

Flexibility Ratio, n

Figure C6 . Case No.l: Rectangular Pulse Input. Maximum Enrl- Wall Force Ratio vs. Lading Flexibility Ratio, for Zg = 0.8 and

B = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0.

Case No. I

3

cM

J.O t.

2.0

1.0

,3 - O.d

S-m I.C

/.O z.o s?.o "f.o

Flexibility Ratio, n

Figure C7 . Case No. 1: Rectangular Pulse Input. Maximum EndWall Force Ratio vs. Lading Flexibility Ratio, for Zg = 1.0 and

e = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0.

119
Case No. 2 Zg = 0.0

« ^ t.O ^'O 3.0 <0

Flexibility Ratio, n Figure C8 . Case No. 2: Rapid-Rise Triangular Pulse Input.

Maximum End-Wall Force Ratio vs. Lading Flexibility Ratio, for

Zs = 0.0 and 6 = 0.0, 0.2, 0.T7 0.6, 0.8 and 1.0,

Flexibility Ratio, n

Figure C9 . Case No. 2: Rapid-Rise Triangular Pulse Input.

Maximum End-Wall Force Ratio vs. Lading Flexibility Ratio,

Zo = 0.2 and e = 0.0, 0.2, 0.T7 0.6, 0.8 and 1.0.

120
Case No. 2

Flexibility Racio, n Figure CIO. Case No. 2: Rapid-Rise Triangular Pulse Input.

Maximum End-Wall Force Ratio vs. Lading Flexibility Ratio, for

Zg = 0.4 and 6 = 0.0, 0.2, 0.T7 0.6, 0.8 and 1.0.

Flexibility Ratio, n Figure Cll.Case No. 2: Rapid-Rise Triangular Pulse Input.

Maximum End-Wall Force Ratio vs. Lading Flexibility Ratio, for

Zg = 0.6 and S = 0.0, 0.2, 0.T7 0.6, 0.8 and 1.0.

121
Flexibility Ratio, n Figure C12.Case No. 2: Rapid-Rise Triangular Pulse Input.

Maximum End-Wall Force Ratio vs. Lading Flexibility Ratio, for

Zg = 0.8 and 6 = 0.0, 0.2, 0.T7 0.6, 0.8 and 1.0.

Flexibility Ratio, n Figure C13.Case No. 2: Rapid-Rise Triangular Pulse Input. Maximum End-Wall Force Ratio vs. Lading Flexibility Ratio, for

Zg = 1.0 and 6 = 0.0, 0.2, O.TT 0.6, 0.8 and 1.0.

122
1

a

toB

(0 N Case No. 3 N Zs = 0.0

Flexibility Ratio, n

Figure C14. Case No. 3: Symmetrical Triangular Pulse Input.

Maximum End-Wall Force Ratio vs. Lading Flexibility Ratio, for

Zg = 0.0 and 6 = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0.

M

(0sN Case No. 3 N Zg » 0.2

Flexibility Ratio, n

Figure C15. Case No. 3: Symmetrical Triangular Pulse Input.

Maximum End-Wall Force Ratio vs. Lading Flexibility Ratio, for

Zg = 0.2 and 6 = 0.0, 0.2, 0.T7 0.6, 0.8 and 1.0.

123
JBM Case No. 3 Zs = 0.4

Flexibility Ratio, n

Figure C16. Case No. 3: Symmetrical Triangular Pulse Input.

Maximum End-Wall Force Ratio vs. Lading Flexibility Ratio, for

Zs » 0.4 and 8 = 0.0, 0.2, 0.T7 0.6, 0.8 and 1.0.

s

Flexibility Ratio, n

Figvire C17. Case No. 3: Symmetrical Triangular Pulse Input.

Maximum End-Wall Force Ratio vs. Lading Flexibility Ratio, for

Zg = 0.6 and 8 = 0.0, 0.2, O.TT 0.6, 0.8 and 1.0.

124
»<a

E

Flexibility Ratio, n Figure C18. Case. No. 3: Symmetrical Triangular Pulse Input.

Maximum End-Wall Force Ratio vs. Lading Flexibility Ratio, for

Ze = 0.8 and 6 * 0.0, 0.2, 0. TT 0.6, 0.8 and 1.0.

125
Flexibility Ratio, n

Figure C20. Case No. 4: Slow-Rise Triangular Pulse Input.

Maximum End-Wall Force Ratio vs. Lading Flexibility Ratio, for

Zs = 0.0 and 6=0.0, 0.2, 0.4, 0.6, 0.8 and 1.0.

Figure C21. Case No. 4: Slow-Rise Triangular Pulse Input.

Maximum End-Wall Force Ratio vs. Lading Flexibility Ratio, for

Zs = 0.2 and 6=0,0, 0.2, 0.4, 0.6, 0.8 and 1.0.

126
Figure C22. Case No. 4: Slow-Rise Triangular Pulse Input Maximum End-Wall Force Ratio vs. Lading Flexibility Ratio, for

Zs = 0.4 and 8=0.0, 0.2, 0.4, "0.6, 0.8 and 1.0.

127
Figure C24 - Case No. 4: Slow-Rise Triangular Pulse Input.

Maximum End-Wall Force Ratio vs. Lading Flexibility Ratio, for

Zs =^0.8 and 3=0.0, 0.2, 0.4, 0.6, 0.8 and 1.0.

^ AO S. <J S.O ^.O

Flexibility Ratio, n

Figure C25. Case No. 4: Slow-Rise Triangular Pulse Input.

Maximiim End-Wall Force Ratio vs_. Lading Flexibility Ratio, for

Zs = 1.0 and 6=0.0, 0.2, 0.4, 0.6, 0.8 and 1.0.

128
Figure C 26. Case No. 5: Half Sine Wave Pulse Input. Maxitr.uiT End-Wall Force Ratio vs. Lading Flexibility Ratio, for Zg = 0 .

u

and 6 = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0.

Figure C27 . Case No. 5: Half Sine Wave Pulse Input. Maximum End-Wall Force Ratio vs. Lading Flexibility Ratio, for 0 2 andB=0.0,0.2,0.4,0.6,0.8andl.0.

129
X

E

01 Case No. 5

Flexibility Ratio, n

Figure C28. Case No. 5: Half Sine Wave Pulse Input. Maximum

End-Wall Force Ratio vs. Lading Flexibility Ratio, for Zg =0.4

and B = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0.

Figure C 29. Case No. 5: Half Sine Wave Pulse Input. Maximum

End-V*all Force Ratio vs. Lading Flexibility Ratio, for Zg = 0.6

and e = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0.

130
«

E

Flexibility Ratio, n

Figure C30. Case No. 5: Half Sine Wave Pulse Input. Maximum

End-Wall Force Ratio vs. Lading Flexibility Ratio, for Zg = 0.8

and 6 = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0.

8

Flexibility Ratio, n

Figure C31. Case No. 5: Half Sine Wave Pulse Input. Maximum

End-Wall Force Ratio vs. Lading Flexibility Ratio, for Zg =1.0

and B = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0.

131
SYSTEM FOR TRAIN ACCIDENT REDUCTION--DOT STAR

J. J. Richardson

Naval Surface Weapons Center

Silver Spring, MD 20910

Abstract: The Department of Transportation-System for Train Accident

Reduction (DOT STAR) study at the Naval Surface Weapons Center (NSWC)

is developing a prototype system to help reduce the number of train

accidents. NSWC has taken military technology and applied it to

develop an on-train ant i -derailment system. This system can sense

a local derailment ot a hot bearing. Upon sensing these conditions,

the system automatically applies emergency braking.

Exploratory development hardware of the journal bearing thermal sensor successfully completed over 100,000 miles of travel. A roller bearing

thermal sensor has also been designed. NITINOL is the key component

use to sense over-heated bearings. The derailment detector uses the

impact of a sensor foot with the rail head to sense a local derailment.

Upon generation of a hot box or a local derailment, the sensors

initiate a thermal pulse battery. The electrical pulse activates the

air-valve which applies the train's brakes. To foster the success of

the DOT STAR concept highly reliable, rugged and maintenance free

military-developed components are being used. This document provides

an overview of the DOT STAR program followed by a more detailed presentation of technical aspects of the sensors.

Key words: Bearing thermal sensor; DOT STAR; journal and roller bearing temperature transients; local derailment sensor; NITINOL; railroad

safety system.

DOT STAR Program Initiation: If the Navy applied some of the technology they developed for weapons to help solve the railroad industry's

derailment problem, what would result? The answer to this question is

the Department of Transportation System for Train Accident Reduction

(DOT STAR). The DOT STAR system was developed at the Naval Surface

Weapons Center (NSWC) under the sponsorship of the Federal Railway

Administration (FRA) . This development was undertaken via the Department of Defense's Technology Transfer Program. (Nominally up to 3% of

NSWC's manpower is made available to transferring military developed

technology to other branches of the federal government, state and local

governments, universities and private industry). In this instance, an NSWC employee, knowledgeable of the needs of the railroad industry,

conceived of a system using current Navy technology which could solve

some aspects of the railroad derailment problem. A proposal was submitted to the FRA, was accepted, and the DOT STAR program began.

Establishing Ground Rules and Objectives: The overall objective of

reducing the number of train accidents can be met in a number of ways, some of which are to:

132
a. Increase the quality and/or quantity of inspections and preventive

maintenance. This approach must be evaluated by the railroad industry,

b. Develop wayside monitoring systems which would sense conditions re- lated to imminent derailments. The wayside IR hot bearing sensors, for

example, have been in use for a number of years. A good deal of re- search has already been done in this area.

c. Develop an on- train detection system. This approach is the one selected for DOT STAR. For an on-board system to be acceptable, it

should have the following basic features:

o Independent/self -contained

o Very little or no maintenance

o Low cost

o Very low false alarm rate, and

o Monitors multiple causes (for increased cost effectiveness)

All of these features clearly tie back to life cycle cost and re- liability

DOT STAR System Overview: The DOT STAR system is illustrated in Figure

(1) . It has a thermal sensor at each wheel to detect an overheated

whfeel bearing and a local derailment detector (to detect when an axel

derails). These are both ordinary causes of major derailments that

are train (vs. track) related and can be detected and corrective action

taken. The thermal or local derailment sensor electrically sends a signal to a valve which applies emergency braking to the train.

The temperature of the bearing is monitored with the aide of a unique

alloy developed by the Metallic Material Research Branch at the Naval

Surface Weapons Center. The metal is a nickel titanium alloy called

NITINOL. The unique property of NITINOL is that the temperature at

which it undergoes its phase change can be controlled well and once it

is heated to its phase change temperature, the metal will suddenly re- vert back to the shape it had when it was last in that higher temperature phase. In the journal bearing thermal sensor, a NITINOL retaining

ring holds back a spring loaded firing pin. The NITINOL was straight

when it was last in its higher temperature phase, so, when the temperature of the NITINOL retaining ring in the thermal sensor is evevated to

the phase change temperature, the ring suddenly straightens out releasing the firing pin. The firing pin strikes the base of a thermal pulse

battery to activate it. The battery provides a signal to initiate

emergency braking. The thermal sensor for roller bearing cars is con- figurated differently than the journal bearing system described above,

but it also uses NITINOL to sense the temperature.

133
The thermal pulse battery is the only source of electrical energy in

the system. It is a battery developed by the military and is used in

many weapons. It is extremely rugged, has an extremely long shelf life,

will supply full power immediately at temperature extremes from below

-60°? to 160°F and is very reliable. It is the only type of battery

known which meets the environmental and functional criteria of DOT STAR.

The local derailment sensor is basically a contract sensor located outboard (on the field side) of each wheel. When the wheel derails inward

(on the gage side) , it drops and the railhead strikes and depresses

the contact sensor which is located just outside the wheel. A trigger

mechanism in the contact sensor then fires the thermal battery.

After the thermal battery is fired, the wiring conducts the signal to

the air-valve. The air-valve is located in the air clean out system

of the railcars air brake lines. The air-valve vents the train's air

brake system to apply emergency braking to the train.

Thermal Sensors: The geometry of roller bearings and journal bearings

are quite different, but the basic problem of finding a practical

location to mount a thermal sensor is the same. A reasonable lag time

between a temperature change at the wheel bearing and a corresponding

change at the thermal sensor location is essential if the sensor is to

avert a derailment. Identifying that location involved two series of

field tests as well as laboratory tests and finite element thermal

analysis for the roller bearing as well as the journal bearing thermal

sensors

.

Journal Bearing Thermal Sensor: The first series of field tests in

November 1974 revealed that it would be impossible to detect an over- heated journal bearing by monitoring the temperature of the journal

housing. The second series of field tests conducted in July of 1975

had a sensor as shown in Figure (2) . This figure also indicated where

the thermal sensors and thermocouples were located. Note the thermal

sensor penetrates the journal bearing housing and the sensing head is

spring-loaded to remain in contact with the wedge. Figure (3) illustrates the top surface of the bearing wedge follows the temperature of

the bearing under normal operating conditions. Figure (5) illustrates

how the temperature of the surface of the wedge followed the bearing

during a generated hot box. During this series of tests, operative

sensors were installed at the right and left wheels. The left bearing

sensor actually stopped the train when the sensor reached approximately

240OF ~ the designed activation temperature) . Reference (a) provides

additional information on these journal bearing thermal sensor tests.

The journal bearing thermal sensors were installed on four ore cars at

the DM^IR Railway in Minnesota and were left to ride around for five

years of normal operation. They saw well over 100,000 miles. They

were all removed from the cars and tested in the laboratory. Each

sensor activated its thermal battery properly and the battery provided

the required power to initiate the air valve.

134
Roller Bearing Thermal Sensors: As with the journal bearing thermal

sensor, finding a location that is practical and provides a good

response time is equally important for roller bearing thermal sensors.

To identify that location, a series of tests were conducted at the

Transporation Test Center in Pueblo, Colorado, during December 1977

and July 1978.

The first step in the testing was to determine the operating tempera^

ture of the roller bearing at various loading conditions, velocities

and ambient temperatures. It was assumed the 240°F chosen for the

journal bearing activation temperature would also be good for the

roller bearing sensor. Figure (6) illustrates how a roller bearing is

mounted on a sideframe. The air blowing around and cooling the outer

surface provied to be a major factor in selecting a sensor location

point. The roller bearing and adapter are further illustrated in

Figure (7) . This figure shows the heat indicator holes designed into

the adapter but they are seldom used. The base of these holes, if

they were drilled to the proper size and tapped, were determined to be

a possible location for the thermal sensor, which would not be as influenced by the convective cooling.

During the tests in July 1978, thermocouple #1 was imbedded in the

saddle of the adapter. It was in contact with the race of the roller

bearing directly above the outer bearing, which was run in a non- greased condition to induce bearing seisure. The temperature sensed by

the thermocouple #1 was considered to be the operating temperature of

the bearing. There were a total of 14 thermocouples installed to

obtain data to develop the heat transfer model for the roller bearing

system and evaluate sensor locations.

Figure (8) illustrated the temperature of thermocouples during the

attempt to generate a derailment due to roller bearing seisure.

Thermocouple #11 was located at the outer surface of the adapter where

sensor #1 is attached. Thermocouple #8 was located in thermal sensor

#3 which was located in a heat indicator hole. As can be seen from the

figure, sensor #3 triggered in a timely manner and in general, thermocouple #8 followed thermocouple #1 quite well. Thermocouple #11 re- sponded to the temperature rise in the bearing nearly as rapidly as thermocouple #8 but at a lower rise rate so it only reached 180°F

during the time the bearing was seized. Thus for sensor #1 to activate

in a timely manner it should have a NITINOL element which activated

around 180°F. Generating and maintaining a seisure of a roller bearing

is not a simple problem, especially if you do not wish to cause an axel failure to occur at high speed. See reference (b) for an explanation of the unusual velocity profile and other details of these two

test series and the finite element analysis which follows.

A heat transfer analysis of the roller bearings was performed using a computer code designed by the Army to evaluate head conduction in

rocket motor nozzles. A portion of the model used is illustrated in

135
Figure (9) . The modeling of the adapter has been omitted for clarity.

The heat generation rate and convective heat transfer coefficients

were selected using temperature data generated during testing. After

the model was developed, it was run for various velocities, ambient

temperatures, etc. The model indicated that the sensor located in the

heat indicator hole would reach 240°F at the time the surface of the

roller bearing reached 300°F. The analysis predicted a 300°F bearing

operating temperature would only result from conditions beyond worst

case for normal train operation anywhere in the world. TIMKEN Roller

Bearing Company engineers verified that they would not want roller

bearing to operate at 300°F for any sustained period. Therefore, 240°F

appears to be a good activation temperature for a sensor located in the

heat indicator hole.

At the time of the study using a thermalsensor very similar to the

journal bearing sensor and locating that sensor in the heat indicator

hole seemed like the best approach. During the design phase, as attempts were made to address the AAR regulations and the vulnerability

of the sensor in the railroad environment, the face of the adaptor was considered a much more practical location for the sensor.

The roller bearing system finally designed is shown in Figure (10).

The NITINOL wire in this design shortens when it reaches its phase

change temperature (approximately 180°F) . The NITINOL pulls a cable

which trips a lever in the derailment sensor to fire its battery.

(This saves the cost of a separate battery for the thermal sensor)

.

Laboratory tests have been conducted on this new design, but no field

tests have been conducted to verify it.

Local Derailment Detector: The original approach for a local derailment detector was to develop a seismic device that would trigger when

the wheel dropped from the railhead to the road bed or in the shocks

from riding over the railroad ties. It was determined, however, that

the on-track shock environment (including coupling shocks, etc.) varies

sufficiently between winter and summer with velocity and with various

track conditions that a non-sophisticated seismic type which would re- liably sense a local derailment but not give false alarms would be

difficult to design. Early seismic type sensor work including test

data is included in reference (c)

.

The present local derailment sensor uses a contact sensor. A contact

foot is located 3-1/4 inches above the railhead just outside of the

wheel. During a local derailment the sensor adjacent to the wheel

which derails on the gage side, is activated by impact with the railhead as the wheel drops . See Figure (11). The sensor is designed to

function only on vertical loads in excess of 7,000 pounds. A 7,000

pound load will shear the pins allowing the foot to move upward into

the sensor body. When the foot is pushed far enough upward, a trigger

mechanism is released and a thermal battery activated. The sensors

are located so as to be partially shielded by the side frames.

136
During recent tests at the DM^IR Railway, the local derailment detector

gave a false alarm at a grade crossing where the freezing conditions

had heaved the asphalt up as much as 3-3/4 inches above the railhead.

This raised asphalt (somewhat like a ramp) struck the underside of the

contact foot and activated the sensor and stopped the train. The

location of the local derailment detector can be changed to reduce the

probability of this recurring. Subsequent to the impacts with the

grade crossing, two other derailment detectors have been lost. Damage

done at the grade crossing is suspected as the cause.

Air-Valve: After a thermal battery is fired either by the thermal

sensor or local derailment sensor, it sends a pulse of electricity to

the air-valve. The air-valve is located in a little extension added

to the air clean-out assembly. See Figure (12) . The air-valve is

powered by a pyrotechnic gas generator. The gas generator pushes a piston which punctures a diaphragm to allow the pressure in the brake

lines to vent. An orifice can be added to the air-valve to limit the

vent rate to that of standard braking. Emergency braking is the vent

rate used in the test hardware.

NSWC has a great deal of experience developing pyrotechnic compounds

and devices. This device is completely enclosed, containing even the

gases generated. The pyrotechnic has the standard one watt, one amp

no fire safety feature to prevent activation due to the discharge of

static electricity. The conduit and junction boxes protecting the

wiring from the railroad environment inherently provides the required

shielding against electromagnetic radiation. This shielding prevents

currents (and the resulting braking) from being induced by transmissions' from local radio stations, radar, etc.

Concluding Remarks : NSWC, through the sponsorship of the FRA, has

done a lot of work developing and proving the technology for building

the DOT STAR system. A detailed description of some of the testing

(including a lot of data) can be found in references (a) , (b) , and (c)

.

The design of the thermal battery and the environmentally protected

wiring system for DOT STAR has been omitted to meet the presentation

time limitation.

REFERENCES

a. FRA/ORD-80/76, PB 81-127458, Thermal Sensing Unit Test for

Railroad Car Journal Bearings, October 1980

b. FRA/ORD-80/43, PB 80-193758, Railroad Car Roller Bearing

Temperature Measurement and Analysis, April 1980

c. FRA/ORD-80/75, PB 81-127466, G-Sensing Derailment Detector

Final Report, October 1980

137
JOURNAL BEARING APPLICATION

PISTON SENSOR LOCATIONS

^^'^ SHEAR

PIN

ACTUATOR VALVE

FIGURE 1 D.O.T. SYSTEM FOR TRAIN ACCIDENT REDUCTION (S.T.A.R.) DERAILMENT SENSOR

SENSOR HOUSING

THERMAL SENSORJOURNAL BEARING. HOUSING

OLD SEISMIC DERAILMENT SENSOR

JOURNAL^

TO

ACTUATOR

VALVE

/PsENSOR CONTACT

THERMOCOUPLES

FIGURE 2 SENSOR ASSEMBLY ON JOURNAL HOUSING

138
139
TIME (MINUTES) FIGURE 4 OVER-THE-ROAO. TEMPERATURE MAXIMUMS, FULL CAR. JULY 1975, RIGHT

- (500)

5 (10) 15 (20) TIME (MINUTES)

FIGURE 5 HOT BOX TEMPERATURES AND TRAIN SPEED VS TIME, JULY 1975, RIGHT BEARING

140
FIGURE 6 ROLLER BEARING AND BEARING ADAPTER

141
HEAT INDICATOR HOLES

INTERNAL CONTACT

00,0.. SENSOR NO. 2

-3-3/8 MIN.—

n

INTERNAL CONTACT

SENSOR NO. 3

SECTION THRU HEAT INDICATOR HOLE

INBOARD ROLLER RACE OUTBOARD ROLLER RACE

THERMOCOUPLE

LOCATION 3 THERMOCOUPLE 1

THERMOCOUPLE 13 RAILROAD CAR BEARING CUT-AWAY VIEWS

THERMOCOUPLE 12

FIGURE 7 HOLES IN BEARING ADAPTER FOR INTERNAL CONTACT THERMAL SENSORS

1531

TEMPERATURE

DEGREES F

600

500

400

300

200

100

THERMOCOUPLE 8 SENSOR NO. ADAPTER ^

y

"—^ SENSOR NO. 1

-PRE TEST«J MOVEMENT

THERMOCOUPLE 11

BEARING

8 - INSIDE SENSOR NO. 3

1 • BEARING TO ADAPTER INTERFACE OVER OUTBOARD ROLLER RACE

11 - ON SENSOR NO. 1

30 —»^ 60 30 45 MPH MPHMPH MPH |«— 50 MPH — 12 »| 3 4 TIME IN HOURS

FIGURE 8 OVERHEATING RAILROAD CAR BEARING TEMPERATURES THERMOCOUPLES

142
SSOT aV3H ON a3ivinsNi

u

92Z'9 eW)"9 29ee L89"L 000"

143
144
COMMUNICATION LINK TO AIR-VALVE

THERMAL BATTERY HOUSING

TRIGGER MECHANISM

SHEAR PIN

CONTACT FOOT

FIGURE 1 1 CONTACT DERAILMENT SENSOR

LENGTH ADDED TO

AIR CLEANOUT ASSEMBLY

PYROTECHNIC GAS

GENERATOR

PISTON DIAPHRAM

FIGURE 12 AIR VALVE

145

SESSION III

RESEARCH IN THE RAILROAD INDUSTRY (continued)

CHAIRMAN: HENRY HAHN

ARTECH CORPORATION

FREIGHT CAR RESPONSE ANALYSIS

AND

TEST EVALUATION MODEL

(FRATE)

Claire L. Orth

Federal Railroad Administration

Washington, DX. 20590

George Kachadourian

The MITRE Corporation

McLean, Virginia 22102

Abstract: This paper gives an overview of the computer model, FRATE,

which simulates the dynamic responses of a 70-ton boxcar to various

track conditions. The FRATE model can, using over-the-road input

motions, define the response displacements, accelerations, and loads of

the freight car. A recent test utilized an actual 70-ton boxcar on the

Vibration Test Unit at the Transportation Test Center, Pueblo, Colorado,

to collect data for validating this model. The preliminary results will

be presented here.

Key words: Freight car dynamic response; freight car model; hunting

simulation; dynamic loads. .

The dynamic response of rail vehicles influences safety and cost in the

operation of railroads, because it affects the wear of rail car components, rails, track, and roadbed. This extreme dynamic response of a rail vehicle can cause or be a contributing cause of derailments as well

as a cause of lading damage. Accordingly, the capability to analytically study vehicle dynamic response can be very useful. Further, if a computer model is used for an analytical study it requires a computer

program that is convenient from a user's view point, is economical to

use, has demonstrated accuracy and can be modified to simulate rail car configuration or design changes.

The Federal Railroad Administration (FRA) has been investigating the

use of dynamic models to determine the responses of rail vehicles to

various track conditions. The MITRE Corporation under contract to FRA

has developed the FRATE simulation model. FRATE is the acronym for

Freight Car Response Analysis and Test Evaluation. In 1976, one

version of the model, a trailer-on-flatcar (TOFC), underwent validation

testing using the Vertical Shaker System at the Transportation Test

Center (TTC) in Pueblo, Colorado. Since then, the model has been modi149
fied to analyze boxcar response characteristics. Validation of the

boxcar version is currently being conducted.

A recent test used a high cube, 70-ton boxcar to obtain data to validate the latest version of the FRATE model. Testing was conducted in

two phases. First a characterization test was performed on each truck

to measure its stiffness and damping properties. Secondly, the complete

boxcar was tested on the Vibration Test Unit (VTU) at TTC. Four boxcar

configurations were tested on the VTU: the boxcar loaded with cans in

corrugated containers with and without friction snubbers in the trucks;

the empty boxcar without snubbers; and the boxcar loaded with cans in

stretch wrap, with friction snubbers. Resonant frequencies were found

for the boxcar suspension system, the boxcar body torsion, the boxcar

body bending, and the cargo in lateral and vertical motions. Determinations were made of the responses of the vehicle system to two trackprofile simulations and a body-hunting simulation. Two shipping

materials were used to ascertain if there was a difference in input

from the cargo (resonances) to the boxcar during transit. Michigan

State University is analyzing the cargo data, and results should be

available in January 1982. Validation of the boxcar version of FRATE

should be completed by July 1982.

Stationary rail vehicles weighing up to 160 tons can be subjected to

controlled vertical and lateral vibration inputs at the wheels on the

VTU. These vibrations create the dynamic effects of perturbed track.

Excitation is supplied by 12 hydraulic actuators: 8 vertical (one at

each wheel) and 4 lateral (one at each axle). The shaker system is

computer controlled. The data acquision system has a recording and

processing capability with on-line and off-line data display. Currently, the VTU is undergoing modifications to permit easier and less timeconsuming preparations for tests.

FRATE Model

The FRATE computer program calculates the dynamic response of freight

cars to track inputs. The basic program is nonlinear, written in

FORTRAN (currently for Control Data Corporation computers), with

solution in the time domain by numerical integration methods. The two

versions are FRATXI, for the analysis of boxcars, and FRATFI, for the

analysis of trail er-on-flatcar (TOFC). The program permits the user

to perform time history analyses; various track profile variations can

be simulated and the resulting freight car responses are calculated

The FRATE program can be used to study the dynamics of various freight

car configurations and track geometry conditions. Loads on both track

and freight can be determined and safety margins can be evaluated, thus

providing a means for defining and controlling operational safety

margins. The FRATE program can also be used to evaluate innovations to

freight cars.

150
The computer program FRATE is a synthesis of models and analyses by

M. Healy, P. Ahlbeck, and P. Abbott. The truck model, unique in this

MITRE version, contains the following additional features.

1. Truck suspension in roll has been changed from bilinear to

trilinear, whereby the center plate lift is simulated.

2. Friction snubbers and hydraulic snubbers have been added.

3. A lading model has been added.

4. The wheel and rail lateral stiffness have been made bilateral

to simulate conditions with and without flange contact.

In the FRATXI version, the boxcar has a rigid body mounted on two trucks

and contains rigid and compliant lading. The combination boxcar and

lading are symmetrical along the longitudinal and lateral axes. The

center of gravity of the combined boxcar and lading is located midway

between the trucks and is on the longitudinal centerline. The boxcar

structure in FRATXI is a six-sided hollow box with all but the bottom

of equal thickness. The lading is divided into five parts, one rigid

and four spring mounted.

Validation Methods

In the validation of the model, there are two categories of comparisons

which can be made: one is to make a direct comparison of the experimen'tal and analytical response to a known in put at the rail; the other

is to compare the dynamic characteristics of resonant frequencies,

deflection shapes at resonance, and amplification at resonance. The

test methods used are generally referred to as response testing and

modal testing. Each comparison has its advantages. The response com- parison gives a more direct measurement of the predictive accuracy of

the computer model. However, to be done properly, a wide range of

possible track variations must be input and responses over a representative portion of the freight car must be compared. The problem is

compounded by the nonlinear characteristics of the freight car; for

example, it would be necessary to see the effects of the amplitude of

the rail variation and the effects of freight car loading.

Comparison of modal characteristics is more tractable in that there are

five or six resonances that need to be compared in the typical freight

car. These are low center roll, high center roll, yaw, vertical bounce

and pitch. In some freight cars, it may also be necessary to measure

the additional resonances of body torsion and body bending. To

identify and measure the characteristics of these resonances in the

laboratory is a reasonable project. Evaluation of the effects of non- linearities can also be accomplished.

151
Validation through comparison of modal characteristics also has the

advantage of providing clues as to the causes and cures for differences

between analytic and experimental results.

Modal testing of large complex structures has been used for many years

for the validation of math models. Following are the four basic excitation methods which have been used.

1. Single-point sine using frequency sweeps to identify modes

and dewlls to measure modal characteristics

2. Multiple-point sine, sweep and dwell

3. Single-point random input

4. Transient input

All of these testing methods are based on linear undamped systems and

become ineffective with damped or nonlinear systems. Of the above four

methods, the multi-point sine, sweep/dwell test has probably had the

widest use, has proven reliability and is least susceptible to modal

test problems due to damping and nonlinear properties.

There are computer aided techniques that have been used with singlepoint random and transient inputs with outstanding success as to the

number of modes identified, accuracy and cost effectiveness. However,

the successful applications have all been with linear, lightly damped

systems. To attempt to use these methods for a freight car vibration

test is likely to result in an open ended development program.

In the validation of FRATXI, both the vibration characteristics and the

dynamic response parameters with be used. The vibration criteria will

determine whether the general, overall dynamic characteristics of the

vehicle have been accurately simulated. This is important since one function of the validated computer program-simulation could be to investigate the effects of modifying parts within the vehicle. Examples

are: side bearing changes, or the addition of or changes to hydraulic

snubbers, or changes in the spring rate of the truck primary suspension

system. It is necessary that the physical part and its mathematical

counterpart be clearly identifiable and properly modeled so that not

only is the basic model valid but also the accuracy of the simulation

is retained with moderate changes to components. The dynamic response

criteria will provide a more direct measure of the accuracy of the

analysis

.

The dynamic characteristics of the boxcar model to be used in the validation include resonant frequencies, deflection shape at resonance,

damping associated with each resonance, and the dynamic response at

selected points on the boxcar. -

152
The vibration testing was used to obtain definitions of the vibration

characteristics of the test configuration that could be used for com- parison with the analytical model. Resonance testing and response

testing were performed.

Pretest analyses were performed duplicating the planned test. These

analyses served two purposes. First, they were a guide in the performance of the testing: that is how to test and what to expect in

results. Second, the pretest analysis results were used in the initial

comparison between test and analysis results in the validation process.

This initial comparison was made while the test was in progress and as test results become available. This was an aid in knowing that all

resonances have been identified and that sufficient data had been

obtained for the validation process.

The resonant frequencies determined in the pretest analysis are listed

in Table 1. The frequency tolerances shown are the difference between

test results and analysis results which are not to be exceeded.

Preliminary Test Results

Both trucks of the test boxcar were tested under a variety of test

conditions to show the effects of friction snubbers and freight car

gross weight. The three types of tests performed included: vertical

loadings to obtain vertical spring rates and snubber forces; roll

loadings to obtain roll spring/snubber values; and lateral loadings to

obtain the lateral spring/snubber values. The frequency of load

applications was 0.1 to 0.2 Hertz, slow enough not to introduce any

dynamic effects.

From plots generated, it was determined that the truck spring rate was 21,000 pounds per inch per side. The snubber friction force ranged

from 2,250 to 5,250 pounds, as the vertical load varied from empty to

75-tons. These numbers were very close to the expected results.

The test resonant frequencies of primary interest were expected to fall

in the 0.5 to 10.0 Hertz range, with those of secondary interest out to

35 Hi. It was also expected that maximum responses in the 0.5 - 35 Hz

range would not exceed 2.0g (0-peak).

Two characteristics of the acceleration data made measurement difficult.

First, the low frequencies -- 0.5 Hz g levels -- were on the order of

0.5g's. Second, higher frequency transients were superimposed to on

the low frequency excitations.

A preliminary analysis of the vibration test data has been completed.

See Table 2.

Configuration lA is the boxcar loaded with cans in cartons and with

active friction snubbers. Configuration IB is loaded the same as lA

153
TABLE I

VALIDATION CRITERL\ - VIBRATION CHARACTERISTICS

Resonance

Descriptions

Frequency

(pretest analysis)

Hertz

Freq.

Tolerances

low center roll 0.7* + 151

high center roll 1.6 t 101

yaw 1.7 t 101

vertical bounce 2.2 + 10%

pitch 2.9 ± 101

carbody torsion

carbody bending

lading - lateral 5.0 t m

- vertical 9.5 t 10%

*Where resonances are non-linear with respect to an^jlitudes, the

analysis will duplicate the non- linear effect.

5

I

154
8

8

9

8

l-H 1

2;o

00o00

^0

00

00 fM

to

00

vO

< <

o

4-> s •6 I

o

00iH

t r-

/—

\

i-H

^—

vO i-H 00

r 1 o»

o

00

00

00

to

f

155
with inactive friction snubbers. Configuration 2 is an empty boxcar

with inactive friction snubbers. Configuration 3 is the boxcar loaded

with cans in stretch wrap, with active friction snubbers.

In comparing the predicted values with the measured values, it is seen that the first roll mode is close for all configurations. For the

second roll mode this is not the case. Part of the problem may be

that the model predictions were not made for an empty boxcar (Configuration 2); but this does not explain the variation between predicted

and configuration 3 values.

For most all modes there is very little difference between the values

for configuration lA and 3 which seems to indicate that the packing

material for the cans had no significant effect on the input of the

cargo to the boxcar.

The yaw and pitch modes show a difference between the boxcar loaded

with and without snubbers. This indicates that the effect of friction

snubbers is to raise the resonant frequency in the yaw and pitch modes.

The final analysis should be completed by mid - 1982.

References

(1) Healy, M., "A Computer Method for Calculating Dynamic Responses

of Nonlinear Flexible Rail Vehicles," ASME Paper No. T6-RT,

1976.

(2) Ahlbeck, D., "Comparative Analysis of Dynamics of Freight and

Passenger Rail Vehicles," Battele, Columbus, FRA-ORD&D, 74-39,

March 1974.

(3) Abbot, P., G. Morosow and J. MacPherson, "Track-Train Dynamics,"

SAE National Aerospace and Engineering and Manufacturing Meeting, Culver City, California, SAE Paper No. 751058, November

1 975

.

(4) G. Kachadourian and N.E. Sussman, Validation of FRATE, Freight

Car Response Analysis and Test Evaluation, MTR-8007, The MITRE

Corporation, McLean, Virginia, December 1978.

(5) G. Kachadourian, TOFC Lading Response Analyses for Several Track

Profile and Hunting Conditions, MTR-79W00318, NTIS Report No.

FRA/ORD-80/3, The MITRE Corporation, McLean, Virginia, April

1980.

(6) G. Kachadourian and N.E. Sussman, Response Analyses of a Boxcar

with Compliant Lading for Several Track Profile and Hunting Con156
ditions, MTR-79W0031 7, NTIS Report No. FRA/ORD-80/4, The MITRE

Corporation, McLean, Virginia, April 1980.

G. Kachadourian, Vibration Test Requirements for a 70 Ton Boxcar, MTR-80W00149, The MITRE Corporation, McLean, Virginia,

May 1980.

G. Kachadourian, Rock and Roll Analyses of an Empty High C.G.

Freight Car, WP-80W00540, The MITRE Corporation, McLean,

Virginia, July 1980.

157
<

THE ACCIDENT PERFORMANCE OF TANK CAR SAFEGUARDS

William G. Meeker

National Transportation Safety Board

Washington, DC 20590

The mission of the National Transportation Safety

Board is to improve transportation safety. This is done

primarily by determining the probable cause of accidents

through direct investigations and public hearings, and

secondarily through staff review and analysis of accident

information, through evaluations of operations, effectiveness, and performance of other agencies, through special

studies and safety investigations, and through pviblished

recommendations and reports.

BACKGROUND

"Until the late 1950 's liquefied petroleum gases and

other hazardous materials were transported by rail in

11,000-gallon nominal capacity tank cars, now known as DOT Specification 105A tank cars. In 1958, however,

specification changes were allowed v/hich permitted the

use of DOT 112A/114A tank cars having a nominal capacity of

33,000 gallons.

Between 1968 and 1979 DOT 112/114A tank cars were involved in numerous serious accidents. In many of the accidents > couplers disengaged and overrode each other, puncturing the "head," or ends of tank cars. Punctured tank

cars carrying liquefied petroleum gas (LPG) exploded and

fire erupted, resulting in death, injury and extensive

property damage. In some cases, the intense heat from

blazing tank cars caused other tank cars to erupt in

"Boiling Liquid-Expanding Vapor Explosions" (BLEVE's).

Sometimes, sections of steel tank, weighing several tons,

were propelled distances up to one-half mile. Punctures

of tank cars containing other hazardous chemicals resulted

in releases of toxic gases which were carried over surrounding areas by wind currents.

In 1969, following a disastrous accident at Laurel,

Mississippi, the Safety Board first called attention to the

serious problem of head punctures of tank cars by overriding

couplers. As a result of that accident, the Safety Board

made recommendations which addressed coupler design and

called for a progrcim to develop technical improvements to

hazardous materials tank cars. Following the Laurel acci158
dent, the Association of American Railroads, in cooperation

with the Railway Progress Institute, formed a tank car research committee which developed a research and test

project. As a result, in 1971 the committee recommended

installation of tank car headshields and in 1972 and 1973,

recommended installation of "shelf couplers" to prevent

overriding.

In 1974 the Department of Transportation issued regulations requiring that all DOT 112/114 hazardous material

tcUik cars be equipped with headshields by December 1977. The

regulations were challenged in court by some shippers, tank

car owners and lessors, and though the challenge was un- successful, the retrofit program was delayed.

Federal agencies and the railroad and tank car industries were slow to act to improve the situation and after

a series of catastrophic tank car accidents in late 19 7 7 and early 1978, the Safety Board held a pxablic hearing in

April 1978 into derailments and their consequences for the

carriage of hazardous materials by rail. As a result of

the hearing, the Safety Board recommended that the Federal

Railroad Administration accelerate Federal rulemaking

actions to require the installation of head shields and

shelf couplers on U.S. Department of Transportation specifications 112A and 114A cars by December 25, 1978. The

Board also recommended that thermal protection be installed

on tank cars carrying volatile products as soon as possible.

The recommendations resulted in an accelerated safety retrofit program for 112A and 114A tank cars by the DOT. The

Safety, Board' s effort to improve the safety of hazardous

materials tank cars was later expanded to include DOT specification 105A tank cars in a recommendation that resulted

from the Board's investigation of an accident at Youngstown,

Florida, on February 26, 1978. The Safety Board, concerned

about the DOT's response to its earlier recommendation,

recommended in a September 1979 progress report that the shelf

coupler retrofit for 10 5A tank cars be completed by December

25, 1980.

As a result of these Safety Board efforts to improve hazardous materials

tank car safety, it was desirable that the Board review the effects of shelf

couplers, head shields, and thermal protection under actual accident

conditions in comparision to tank cars without this protection to determine

the impact of the new measures and if there were areas where further

safety improvements were required. Therefore, the Safety Board examined

the sequence of events in the derailment of a chemical train near

Paxton, Texas, on September 8, 1979.

This special investigation examined the behavior of each derailed

tank car that was equipped with shelf couplers, head shields, and thermal

coating and compared this behavior with that of cars not so equipped.

This report compared the actual safety results of the new safeguards with the

stated objectives for which they were mandated.

The reconstruction of a railroad accident by developing the sequence of

events affecting each car before, during, and after the accident is not a

159
commonly used procedure, but. It Is essential to revealing the point at which the events exceeded the normal and safe operating limits. In this

special investigation, the analysis was limited to an examination of the

sequence of events from the start to the end of the derailment—a period of

about 80 seconds—and of the ensuing fire and subsequent events. The

Safety Board's task was difficult since the reconstruction was not undertaken

until the wreckage has been cleared. It was possible only because of the

participation and contributions of the ?RA, the Association of Airerican

Railroads, the Railway Progress Institute, the SouJJiem Pacific Transportation

Company, and the tank car owners and shippers whose cars were involved in the

accident. The Safety Board analysis is based on the reconstruction of

events—-the first such analysis of a chemical freight train accident in the

railroad industry.

About 4:22 p.m., c.d.t., on September 8, 1979, 33 cars and 2 locomotive

units of Southern Pacific Transportation Company freight train (chemical)

Extra 1291 East SRASK derailed in a lightly populated area near Milepost

183, about 3 miles east of Paxton, Texas. The train consisted of 53 cars

and 3 locomotive units. The train had descended a 1.6-percent grade, with

locomotive braking in the dynamic mode, and was beginning to ascend a 1.6 percent grade at about 30 mph v^en the cars derailed

on a 20 20' curve on a sj.ngle track. The track was located

on a 15-foot-high fill embankment.

The intent of existing tank car regulations (49 CFR

179.105) is to prevent vertical separation through the use of shelf couplers, to prevent end punctures by the use of

head shields, and to reduce the potential for catastrophic

effects of fire by requiring thermal coating.

Couplers on tank cars have been the subject of Federal

regulations since 1971. Since that date, the FRA has re- quired that tank cars built or rebuilt be equipped with

p-type couplers. The E-type coupler, when coupled to another

E"type coupler or to an F-type coupler, would be expected

to disengage along the vertical plane during compression

(run-in or buff forces) . Vertical disengagement of E-type

couplers would not be expected when they are coupled to

E t/b-type or F t/b-type shelf couplers. F-type couplers

are restrained along the vertical plane when coupled to

other F-type couplers, to E t/b-type sheif couplers, and

to F t/b-type shelf couplers. Cars equipped with E t/btype and F t/b-type shelf couplers also would be expected

to remain coupled.

Title 49 CFR 179.105-6 requires coupler vertical re- straint systems to lessen the possibility of tank punctures

by constraining vertical disengagements of couplers.

During the initial run-in, when compressive forces are greatest, cars with shelf couplers should remain coupled,

and vertical separation (which can result in head puncture)

should not occur.

THE ACCIDENT

160
Four 112 tank cars in the derailment were equipped with

E t/b-type shelf couplers. Examination of the heads of the cars for coupler penetration and dents showed that all four

of the 112 tank cars remained coupled and xindamaged during

the initial run-in; vertical separation did not occur during

this phase of the collision. However, five of the eight

couplers disconnected later in the accident sequence.

The five 105 tank cars involved in the derailment were

equipped with E- and F-type couplers. Title 49 CFR 179.105-6

does not currently require top-and-bottom shelf couplers on this type of equipment. Five of the 10 couplers should have

provided protection by remaining coupled. Examination of

the derailment data shows that the cars equipped with

top-and-bottom or F- to F-type couplers did not separate

along the vertical plane, whereas four of the five couplers

that were expected to separate vertically did; one coupler

could not be evaluated because portions of the tank head

were destroyed by fire.

The 15 specification 111 tank caxs involved in the derailment were all equipped with E- or F-type couplers, except for car No. 26 which had an F t/b-rtype shelf coupler

on its trailing end. It was expected that 8 car ends would

remain coupled, and that 22 car ends would uncouple vinder

compressive forces. The 8 car ends expected to remain

coupled did remain coupled during the initial collision;

21 of the 22 car ends expected to uncouple did uncouple during the initial collision.

By comparing the coupler performance of the cars which

were equipped with protective couplers with those which

were not so equipped, the advantages of top-and-bottom

shelf couplers or F- to F-type couplers become apparent.

These data indicate that all of the car ends with protective

couplers stayed together during the initial run-in. On these

cars, there were no punctures or dents attributable to

overriding coupler strikes on tank heads. In contrast, of

the 27 car ends connected with couplers in which vertical

separation would be expected, 96 percent did, in fact uncouple

None of the cars joined by protective couplers suffered a head pvincture attributable to coupler strike. There were

4 head punctuires and 9 heads dented in the 27 ends without

protective couplers. Clearly, protective couplers provided

significant protection against end penetration during initial run-in.

Head Shields

A major area of concern to the Safety Board has been

the protection of tank heads from puncture. Tank heads are punctured when couplers disengage vertically and strike the

tcink head or when the tank head strikes or is struck by other

objects during a collision. Shielding the tank head is

achieved by attaching a metal plate to the car or tank

structure. This shielding is required by 29 CFR 179.105.5.

161
The intent of the regulatory requirements for tank head

puncture resistance is to provide tank cars with the capability of withstanding specified impacts without loss of lading.

In this accident, the 26 car ends that \ancoupled during

the run-in were susceptible to end coupler strike. There

were 4 punctures and 9 dents or about 1.5 punctures and 4 strikes for every 10 car ends involved. Only four cars

(8 ends) in the derailment were equipped with head shields,

and none, of these cars mcoupled, so the utility of the

head shields as protection against coupler strikes was not

tested in the initial rm-in. Tank car No. 30 was the only

car of this group exposed to head damage as a result of

subsequent strikes during the derailment dynamics, and

it resisted probable head puncture.

The 26 specifications 105 and 111 car ends that uncoupled

in the initial phase of the accident, as noted before, re- sulted in 4 head punctures and 9 heads dented. In other

terms, 7 mprotected cars in 10 suffered a head strike and 3

in 10 were punctured. If head shields and shelf couplers

had been in place, the likelihood of punctures would have

been' reduced. The nine dented heads on \inprotected cars clearly demonstrated a potential for penetration.

Thermal Protection

The intention of the requirements of 49 CFR 179.105-4

for thermal protection is to prevent the release of any of

the car's contents (except release through the safety valve}

when subjected to (1) a pool fire for 100 minutes, and

(2) a torch fire for 30 minutes.

In this derailment, two 112 cars with thermal protection,

Nos. 7 and 30, were exposed to fire. There was no apparent

release from car No, 30. A large bum hole developed in car No. 7, through which the cargo was released, but the

car did not rupt\ire violently. The cause of the failure of

car No. 7 is not known.

Some 111 and 105 cars are insulated to reduce the effects

of solar heating. Although this insulation was not intended

to protect these cars in a fire environment (as are installations of thermal protection) , tests made by the FRA have shown

this insulation protects against a 2,200° f fire for 20

minutes. In contrast, the tests showed that a bare tank will

survive the same environment for only 4 minutes.

Twelve of the 24 cars involved in this accident were

neither punctured during the run-in nor in the collisions

that occurred after the cars left the tracks. Six of these

cars were in a fire environment that permitted an evaluation

of the survivability of these cars. All three of the exposed cars, Nos. 9, 13, and 30, had some form of thermal

protection or insulation; one of the 3 cars that failed. No. 8,

had neither and ruptured violently. The other two cars that failed, Nos. 6 and 14, had 4 inches of fiberglass in162
sulation. Car No. 6 was breached by fire impingement, or

may have had an undetermined head puncture. Car No. 14

ruptured violently. Although not conclusive, the evidence

indicates that thermal protection and insulation delayed

violent ruptures.

Car Damage and Loss of Product

The reconstruction of the events of this accident demonstrated that although the requirements of 49 CFR 179.105

reduce the potential for punctures during run-in and decrease

the likelihood of BLEVEs, car damage and loss of product is

still a problem. The investigation showed that (a) 18, or

82 perce.nt, of the breaches resulted from collisions that

occurred after the cars left the tracks, (b) 78 percent of

the breaches resulted from damage to the top fittings or bottom outlets, and (c) large tears in the sides of tank

cars resulted from collisions with boxcars or other tank

cars. While all of these causes of product loss may not be

controllable at this time, the release of product from 12

tank cars (50 percent) through top fittings or lower outlet

fittings can be precluded by corrective action. Safety

benefits can be expected through design protection of the

lower outlet leg area. The technological feasibility of

protection to the fitting is proven. It has been est adDli shed

that "skids," protective structures around the valve, provide protection to lower outlet valves. The outlet (lower)

valves can also be protected by recessing them above the

shear line of the tank structure.

One tank car manufacturer now offers tank cars equipped

with an "internal ball valve" that is located inside of the

t'ank. A customer of this car manufacturer orders this valve

on all new tank cars. While top fittings have not received

comparable attention, the same technology could be applicable to top fitting designs. Protection neer^s to be applied expeditiously to the existing fleet of hazardous

materials tank cars to limit the potential for product loss.

163
RECOMMENDATIONS

OF THE

NATIONAL TRANSPORTATION SAFETY BOARD

As a result of the special investigation, the National

Transportation Safety Board recoramended that the U. S.

Department of Transportation;

Extend the requirements for top-and-bottom shelf couplers

to all tank cars used to transport hazardous materials.

Extend the requirements of 49 CFR 179.105, including those

for head shields and thermal protection, to include new

and rebuilt specification 105 tank cars. Examine specialty products and Class A poisons which are shipped in Type 111 tank cars to determine if the toxicity

hazard is sufficient to justify the protection afforded

by 49 CFR 179.105.

Take inmiediate steps to cause the modifica'dion of both new

and existing tank cars so that damage to the top fittings

and bottom outlet valves is minimized in train accidents.

Cause data to be collected on tank car derailment behavior

to identify breach mechcinisms, analyze these mechanisms,

identify control methods, and incorporate findings in new

car construction.

Conduct tests of tank cars in freight train derailments to

determine if the severity of collision damage can be reduced

by tank car placement in trains. Identify and test countermeasures.

Require crashworthiness testing of new hazeirdous materials

tank car designs to resist breaching in the derailment environment .

164
RAIL TANK CAR IMPACTS

David M. Dancer

U.S. Federal Railroad Administration

Washington, D.C. 20590

Abstract: This paper describes the Federal Railroad Administration's research

efforts to mitigate the consequences of impacts to rail tank cars.

Key words: Metallurgy; puncture prevention; structural integrity; non-destructive testing.

INTRODUCTION

In recent years there has been a number of railroad accidents involving hazardous

material tank cars. Many of these cars were Department of Transportation

specification 112 or 114 tank cars, and the initial research and regulatory efforts

of the Federal Railroad Administration (FRA) were directed primarily at those

specification tank cars. However, since tank cars of other specifications (e.g.

105 and 111) have also been involved in railroad accidents, current FRA research

and regulatory efforts concern these other specification tank cars.

In 1970, FRA initiated a research program to reduce the frequency and severity

of hazardous material accidents on railroads. For the two areas of research

involving tank car impacts, FRA is trying to reduce the frequency of the release

of hazardous materials in impact situations and developing techniques for

assessing the structural integrity of rail cars subjected to impacts. This paper

describes the past and present research efforts in these two areas. HAZARDOUS MATERIAL RELEASE PREVENTION

The release of hazardous materials in railroad accidents can produce catastrophic consequences. In several incidents a tank car carrying a flammable

material has been punctured, fire engulfed adjacent cars, and these adjacent

cars ruptured violently causing deaths, injuries, and property damage (1-9). There

have been other incidents where a tank car carrying toxic material was

punctured and the escaping vapor killed and caused injuries (10-14). In still other

incidents, a tank car carrying a flammable material was punctured, the resultant

vapor cloud drifted downwind, was ignited, and led to deaths, injuries, and

property damage (3, 15-18).

Since 1970, FRA has had an interagency agreement with the National Bureau of

Standards concerning the metallurgy of tank car steels. This research has

disclosed a wide variation in the fracture toughness of tank car steels. Current

155
research is aimed at developing guidelines for cost effective improvements in

tank car steels.

Although improvements in tank car steels would increase the puncture resistance

of new cars, they would not solve the problem of puncture resistance for existing cars which have a useful life of 40 years. Accordingly, the FRA has sponsored

research and analysis that could be incorporated in existing cars.

An analysis of the FRA accident data from 1969-1974 for specification 112 and

114 tank cars has shown that approximately 84 percent of the tank punctures

occurred at the head ends of the cars and 16 percent in the shell (19). As

presented in Figure 1, additional analysis indicates that most of these head

punctures occurred in the lower half of the heads (20). Therefore, by providing

puncture resistance only at the lower half of the tank heads (approximately 3.8%

of the total tank car surface area), a significant reduction in the releases of

hazardous material could be achieved. Furthermore, many head punctures occur because the couplers of adjacent cars become uncoupled, and one coupler acts as a "hammer" and punctures an adjacent car. If coupler disengagement could be

reduced, a further decrease in the release of hazardous materials could be

achieved. ^5

In light of the above discussion, FRA, the Association of American Railroads

(AAR), and the Railway Progress Institute (RPI) conducted research (in many

instances, jointly) to develop cost beneficial methods of head protection and

coupler vertical restraint systems. Jointly sponsored field tests at the

Transportation Test Center showed that although neither head shields nor shelf

couplers alone were effective in all accidents, the combination of the two safety

devices was effective in €ill tested accident situations (21, 22).

In 1980, under a contract to FRA, Biotechnology undertook the development of an analytical methodology for predicting the vulnerability of tank cars to

railroad impacts. It is concerned with tank car material properties, head shield

material properties, tank car/head shield design characteristics, lading being

transported, ambient conditions, and projectile characteristics. This study is scheduled to be completed in 1982.

STRUCTURAL INTEGRITY ASSESSMENT

Even if a tank car does not rupture during a railroad accident, its structural

integrity may be so impaired that it will rupture unexpectedly at some later

time. In at least two instances the tank cars did not rupture at the time of the

railroad accident, but ruptured several days later causing deaths, injuries, and

property damage (23, 24). The apparent cause was the increase in vapor pressure

of the cargo in the tank car due to an increase in ambient temperature;

consequently, the burst strength of the damaged tank cars was exceeded. Other

explanations have also been advanced for these type of accidents (25, 26).

The AAR Bureau of explosives (BOE) has long recognized the problems posed by

damaged tank cars and has adopted guidelines for assessing tank car structural

integrity based solely on visual inspection. The BOE considers cracks in the base

166
metal, no matter how small, are sufficient justification for unloading the tank as soon as possible. According to the BOE, the following conditions are sufficient cause for a tank car to be unloaded without moving it:

1. A crack combined with a dent or gouge.

2. A dent combined with a gouge.

3. A dent that crosses a tank seam weld.

4. For tank cars built before 1966, a dent with a radius of curvature less

than 4 inches.

5. For tank cars built after 1966 (presumably made of AAR M-128 steel), a

dent with a radius of curvature less than 2 inches.

In 1979, FRA and the U.S. Air Force initiated joint research on post accident

procedures for hazardous material accidents. One aspect is the assessment of

the structural integrity of those tank cars involved in railroad accidents. The

study concluded that although there is a sound technological basis for the BOE

visual guidelines, often tank car defects will not be visible. For example,

insulated tanks cannot easily be inspected for defects. Defects on the inside or underside of a tank are not observable. Also environmental conditions, such as darkness, rain, and dirt on surface, etc.; make visual detection of defects

difficult. In addition, there may be a danger to personnel who are performing

these time consuming visual inspections on the damaged tank cars. The joint

study has identified acoustic emission techniques as a promising method for

assessing tank car structural integrity. These techniques permit remote,

continuous monitoring of the tank car once the detector has been attached.

Magnetic detectors can be rapidly attached to the tank car surface.

CONCLUSION

In summary, FRA has sponsored research to reduce the frequency of releases of

hazardous materials during impacts and to assess the structural integrity of tank

cars subjected to impacts. Recent accident data indicate that this research has

resulted in a significant decrease in the number of hazardous material releases

(27).

167
REFERENCES

1. "Railroad Accident Report, Pennsylvania Railroad Train PR-llA, Extra 2210

West and Train SW-6, Extra 2217 East, Derailment and Collision, Dunreith,

Indiana, January 1, 1968," National Transportation Safety Board, Report No.

SS-R-2, 1968.

2. "Railroad Accident Report, Southern Railway Company Train 154, Derailment with Fire and Explosion, Laurel, Mississippi, January 25, 1969,"

National Transportation Safety Board, no report number, 1969.

3. "Railroad Accident Report, Illinois Central Railroad Company, Train Second

76, Derailment at Glendora, Mississippi, September 11, 1969," National

Transportation Safety Board, Report No. NTSB-RAR-70-2, 1970.

4. "Railroad Accident Report, Derailment of Toledo, Peoria, and Western

Railroad Company's Train No. 20 with Resultant Fire and Tank Car

Ruptures, Crescent City, Illinois, June 21, 1970," National Transportation

Safety Board, Report No. NTSB-RAR-72-2, 1972.

5. "Railroad Accident Report, Derailment of Missouri Pacific Railroad

Company's Train 94 at Houston, Texas, October 19, 1971," National

Transportation Safety Board, Report No. NTSB-RAR-72-6, 1972.

6. "Major Railroad Accidents Involving Hazardous Materials Release, Composite Summaries 1969-1978," pages 82-83, Transportation Systems Center,

Report No. FRA-RRS-80-04, 1980.

7. "Railroad Accident Report, Derailment and Subsequent Burning of Delaware

and Hudson Railway Freight Train at Oneonta, New York, February 12,

1974," National Transportation Safety Board, Report No. NTSB-RAR-74-4,

1974.

8. "Railroad Accident Report, Derailment of Tank Cars with Subsequent Fire

and Explosion on Chicago, Rock Island and Pacific Railroad Company, Des

Moines, Iowa, September 1, 1975," National Transportation Safety Board,

Report No. NTSB-RAR-76-8, 1976.

9. "Railroad Accident Report, Derailment of a Burlington Northern Freight

Train, Belt, Montana, November 26, 2976," National Transportation Safety

Board, Report No. RAR-77-7, 1977.

10. "Railroad Accident Report, Chicago, Burlington, and Quincy Railroad

Company Train 64 and Train 824 Derailment and Collision with Tank Car

Explosion, Crete, Nebraska, February 18, 1969," National Transportation

Safety Board, Report No. NTSB-RAR-71~1, 1971.

168
11. "Railroad Accident Report, Chicago and North Western Transportation

Company, Freight Train Derailments and Collision, Glen EUyn, Illinois,

May 16, 1976," National Transportation Safety Board, Report No. NTSBRAR-77-2, 1977.

12. "Railroad Accident Report, Louisiville & Nashville Railroad Company

Freight Train Derailment and Puncture of Anhydrous Ammonia Tank Cars at

Pennsacola, Florida, November 9, 1977," National Transportation Safety

Board, Report No. NTSB-RAR-78-4, 1978.

13. "Railroad Accident Report, Derailment of Atlanta and Saint Andrews Bay

Railway Company Freight Train, Youngstown, Florida, February 26, 1978,"

National Transportation Safety Board, Report No. NTSB-RAR-78-7, 1978.

14. "Railroad Accident Report, Louisville Si Nashville Railroad Company Freight

Train Derailment and Puncture of Hazardous materials Tank Cars,

Crestview, Florida, April 8, 1979," National Transportation Safety Board,

Report No. NTSB-RAR-79-11, 1979.

15. "Railroad Accident Report, Hazardous Materials Railroad Accident in the

Alton and Southern Gateway Yard in East St. Louis, Illinois, January 22,

1972," National Transportation Safety Board, Report No. NTSB-RAR-73-1,

1973.

16. "Railroad Accident Report, Hazardous Materials Accident in the Railroad

Yard of the Norfolk and Western Railway at Decauter, Illinois, July 19,

1974," National Transportation Safety Board, Report No. NTSB-RAR-75-4,

1975.

17. "Railroad Accident Report, Hazardous Materials Accident at the Southern

Pacific Transportation Company's Englewood Yard, Houston, Texas,

September 21, 1974," National Transportation Safety Board, Report No.

NTSB-RAR-75-7, 1975.

18. "Railroad Accident Report. St. Louis Southwestern Railway Company

Freight Train Derailment and Rupture of Vinyl Chloride Tank Car,

Lewisville, Arkansas, March 29, 1978," National Transportation Safety

Board, Report No. NTSB-RAR-78-8, 1978.

19. Federal Register, Volume 40, No. 79, April 23, 1975, pp. 17853-17854.

20. Everett, J. E. and Phillips, E. A./' Hazardous Material Tank Cars - Tank

Head Protective Shield or bumper Design," Association of American

Railroads, Report No. FRA-RP-72-01, 1971

21. Peters, D. A., Szabo, B. A., and DiboU, W. B., "Tank Car Head Puncture

Mechanisms," Washington University, Report No. FRA/ORD-76/269, 1980.

169
22. Orringer, O. and Tong, P., "Results and Analysis of the Switchyard Impact

Tests," Transportation Systems Center, Report No. FRA/ORD-80/6, 1980.

23. "Railroad Accident Report, Derailment of Louisville <5c Nashville Railroad

Company's Train No. 584 and Subsequent Rupture of Tank Car Containing

Liquefied Petroleum Gas, Waverly, Tennessee, February 22, 1978," National

Transportation Safety Board, Report No. NTSB-RAR-79-1, 1979.

24. Holmberg, M. E., "Rupture of GATX Tank Car 84429 Near Cuming, Iowa,

April 29, 1969," Metallurgical Consultants, Report No. 486-1082, 1969.

25. Lieber, C. O., "Explosionen von Flussigkeits—Tanks. Empirische Ergebnisse-

-Typische Unfalle," (Explosion of Fluid—Containing Tanks. Empirical

Evaluation and Typical Accidents) Journal of Occupational Accidents,

Volume 3, Pages 21-43, 1980.

26. Pellini, W. S., Deposition dated May 29-30, 1980 in re: Waverly, Tennessee,

accident of February 22-24, 1978, United States District Court for the

Middle District of Tennessee, Nashville Division.

27. "Phase 02 Report on the Effectiveness of Shelf Couplers, Head Shields, and

Thermal Shields, Supplement," Railway Progress Institute—Association of

American Railroads, Report No. RA-02-3-44, Supplement, 1981.

170
FIGURf: 1

Head Punctures: Pressure Cars (DOT 112A340W, 114A340W) Generally With Stub Sills. pC marks location of puncture.)

171
A LOCOMOTIVE EVALUATOR-NEW RESEARCH

CAPABILITY THROUGH SIMULATION

J. V. Mirabella

Federal Railroad Administration

Washington, D.C. 20590

Abstract: The Locomotive Evaluator, presently being developed by the Federal

Railroad Administration, is reviewed in terms of the basic difference in approach

between a "research evaluator" and a "training simulator." The new research

capabilities which will be possible with an advanced, real-time train action model

combined with human input in a realistic environment are discussed along with

the potential for improvements in both safety and efficiency.

Key words: Railroad safety; simulation; train handling; locomotive engineer;

training.

New equipment, larger cars, and heavier trains make the job of the locomotive

engineer more complex at a time when many experienced engineers are nearing

retirement age. As a consequence, an increasingly complex job will have to be

handled by newer engineers who must learn the job in a far shorter time than the

engineers they will be replacing. The need for newer and better train- handling

methods and the need to develop more effective training programs have resulted

in the development of plans for a locomotive research evaluator. The locomotive

research evaluator will provide a test subject with a realistic simulation of the

visual, audio, and motion cues that the engineer would experience when actually

operating a locomotive. This requires visual, audio, and motion subsystems that can provide real-time actions dependent on the action of the engineer.

The evaluator differs from training simulators because it will have the added

capability of being a research facility. This capability is a result of:

- increased realism

- high-resolution video system

- ability to provide real-time train simulation

- simulation based on train characteristics and test subject reactions

The evaluator to be discussed has been essentially designed but only partially

fabricated. As shown in Figure 1, a simulated locomotive cab will be mounted on

a motion base. The engineer in the cab will receive visual cues of the chosen

territory, at a rate dependent on locomotive speed.

172
173
The evaluator will be capable of using films available for other training

simulators but will also be equipped to use specially generated films, which will

result in a wider field of view and a higher resolution. The projector runs at a

constant shutter speed with variations in the rate at which film is pulled down

dependent on the simulated locomotive speed.

The audio cues received by the engineer is part of a system with a memory,

including digital reproductions of various sounds such as the engine, bell, horn,

and brake pipe venting. These sounds will be combined using volumes and

frequencies that take into account the speed of the train, as well as any dopplers

shifts. A radio speaker will be placed in the cab to give train orders to the

engineer.

Since train dynamics will be modeled in real time, the motion base is a key

element in the evaluator. The motion base requirements call for the 5 degrees of

motions shown in Figure 2; longitudinal, lateral, vertical, roll, and pitch.!./ Yaw

is not thought to be critical as long as the lateral motions are present.

The locomotive cab will be as realistic as possible; an actual cab was modified to

reduce its weight. Controls in the cab will be computer operated to give the

engineer such data as speed and brake pipe pressure. In the evaluator system,

the cab controls will also be the entry point for the engineer. The test subject

will have access to the same controls as in an actual locomotive run.

As shown in Figure 3, all the described subsystems will be itegrated in the

evaluator system. The computer will control the system, but overrides will be

possible by the operator. The planned experiment will be put into the computer,

and data such as track class and grade will be entered into the computer

memory. The test subject will be in the cab, just as an engineer would be in a

real train, and the operator will be at the master controls to provide any desired

inputs. Two projects will give the operator the option of introducing variables

into an experiment. For example, the operator can set the scene to enter a

siding rather than to remain on the main line—if the siding has been

photographed and in the film library.

Having briefly described the evaluator system, I would like to discuss its varied

uses. The idea of train simulation is not new, but the goals of previous

simulators differ from the goals of this locomotive evaluator. Although training

has been the primary goal in the past, the goals for the evaluator also include

research.

To appreciate the need and potential use for a locomotive evaluator, we must

recognize that the locomotive engineer is a key element in the resultant train

forces. For example, for a 75-car train, each coupler would be in either draft or

buff, and an adverse combination of coupler forces could lead to a derailment.

1_/ The current design includes six degrees of freedom.

174
175
176
In 1980, 2,323 accidents were attributable to human factors.^ While not all these accidents could have been avoided by the evaluator, the following examples

show some areas where the evaluator might solve the problems.

Improper use of automatic brake 20 accidents

Improved use of dynamic brake 6 accidents

Employee falling asleep 4 accidents

Buffing or slack action excessive 307 accidents

Lateral drawbar force on curve excessive 92 accidents

These accidents could be addressed through training, new train-handling

techniques, or new train- handling aides. These factors are interrelated to some

extent since, for example, development of train- handling techniques are useful

only if they provide the engineer with information relating to a train-handlir^

technique. At this time, each will be considered separately.

There are two ways in which the evaluator can be used in training. First, the

evaluator can be used as a training simulator by running engineers through the

evaluator to teach new recruits basic locomotive handling, to teach experienced

engineers new train handling techniques or to provide refresher courses. The

second involves the use of evaluator as a research tool. The evaluator can be

employed to develop and test new training programs that may include classroom

training, over-the-road training, or a training simulator. Using the evaluator in

this manner can aid present efforts to develop model engineer-training programs.

As for train-handling techniques, a computer train dynamics model can predict

train action based on predetermined engineer actions, but only a simulator with a real-time train dynamics model can include the engineer in the loop, giving realtime feedback cues based on the subject's own actions and the resultant train

dynamics. This provides input from the engineer that is not available from a computer model and provides the controlled environment not available in over- the-road testing.

The third area is train- handling aids. Here, the evaluator can help answer the

question of what information the engineer needs to handle the train. Too much

information can be as detrimenteil as too little information. If a system were

developed to provide the engineer with coupler force for each coupler in the

train, the engineer would not be able to comprehend the information, and, as a

result, the data would be ignored. On the other hand, if a system could indicate

whether couplers at certain key locations arein draft or buff, the lesser amount

of the data could be of far greater use to the engineer. The determination of the

2/ Accident/Incident Bulletin No. 149, Calendar Year 1980, Federal Railroad

Administration, June 1981.

177
optimum amount of information for the engineer will be a key function of the

evaluator.

Besides its use in training, train- handling techniques, and train-handling aides,

the evaluator can be used in accident reconstruction. In many instances when an

accident occurs, the exact chain of events leading to the accident is uncertain.

Key inputs, such as the exact time the brake was applied or whether the intrain

forces had reached high levels in unfavorable terrain may lead to ambiguities.

Often, the results are several scenarios that "may" have led to the accident. The

evaluator can be used to recreate each of the scenarios, and a determination can

then be made of the feasibility of each and its consequences.

To summarize, the evaluator, a system for both research and training, combines

the features of training simulators, computer train dynamics models, and over- the-road operations. Such a facility can aid in preparing locomotive engineers to

handle trains with an increasing number of heavy cars and locomotives with

increasing amounts of sophisticated, new equipment.

I look forward to a day when we can discuss the evaluator in terms of results

rather than plans.

178
SESSION IV

DAMAGE PREVENTION IN THE RAILROAD INDUSTRY

CHAIRMAN: BRAD JOHNSTONE

PULLMAN STANDARD

DESIGNING FOR DAMAGE PREVENTION IN

THE RAILROAD TANK CAR INDUSTRY

E. A. Phillips

Project Director

RPI-AAR Tank Car Safety Project

3140 S. Federal St.

Chicago, Illinois 60616

Abstract: This paper describes a cooperative industry project between

the railroads and the major tank car companies that has had the objective of improving the safety of tank cars in accidents. The project was established in 1970 following a sudden rash of catastrophic accidents.

Organized to study all aspects of tank car design, the project sought

to find cost effective changes that would reduce the probability of

tank car punctures and fire induced ruptures in the accident environment. Work was divided into 18 technical phases, a major one of which

was the collection of accident data to develop a solid base upon which

to evaluate potential "solutions". In many areas, work was carried out

cooperatively with the Federal Railroad Administration which also had

ongoing research with the same objectives.

This paper describes the various phase activities and the major results

of the research. One has been the retrofitting of 22,000 liquified

compressed gas tank cars with special (shelf) couplers to reduce the

severity of jackknifing and the potential for head punctures. Another

has been the application of head puncture protection (head shields) on

the same cars and the application of fire retardant insulation to 19,000

of the cars. Means also were developed for protecting bottom fittings

from being torn off when cars slide along the ground after being detrucked. The project still continues with major effort comprising ac- cident data collection and evaluation of the need to improve the safety

of other type cars . ,i, -

, • ?

Key words: Damage prevention; hazardous materials transportation;

railroad tank cars; safety research.

I. INTRODUCTION

In the transportation industry, damage to cargo can be very costly, as can damage to the transport vehicles themselves. In the case of railroad tank cars, their cargo, or "lading" cannot be damaged, but it can

be lost. This leads to a dollar loss, but more importantly, in some^ cases it can create a serious hazard. This hazard can be to the environment, to people, or to both.

181
This paper describes a major program which was undertaken to reduce the

hazards of tank car transportation by reducing the probability of lading

release in accidents.

II. THE PROBLEM DEFINITION

To accurately define the problem, a great deal of information was re- quired on tank car accidents. While accident scenarios are infinite

in variety, the most hazardous can be categorized into three general

types

:

(1) A tank car is punctured, flammable lading is released, fire

ensues, and, in a chain reaction sequence, other cars rupture

violently from thermal overheating and segments of the cars are hurled (rocketed) considerable distances. Rocketing can expand the danger zone from the accident site to a radius of

several thousand yards.

(2) A tank car is punctured without ensuing fire, but a hazard is

created by the toxic or contaminating nature of the lading

which is released

.

(3) A tank car carrying liquified flammable compressed gas is

punctured, lading is released without ignition, the area is

flooded with flammable vapor, the vapor reaches a source of

ignition, and a sudden concuss ive fire results.

Mechanically induced punctures are the initiating cause in each case,

and they constitute the basic problem for investigation. Were they

totally preventable, there would be no other problem to solve. Because

no practical solution will prevent all punctures, the fire induced

rupture is also a matter for study. A solution which improves puncture

resistance reduces the probability of rupture (and rocketing), but a solution which shields a tank car against fire even further reduces

these hazards. In other words, the effectiveness of a puncture shield

and a thermal shield are additive. Both puncture shields and thermal

shields were developed under this program. Methods of reducing the

probability of rocketing, given a thermal rupture, were also investigated, but no practical solutions were found.

III. ORGANIZING TO ATTACK THE PROBLEM

Figure 1 from ref. {44}^'^ illustrates an accident peak which occurred

in 1969. There is no explanation for it, and it has to be considered

a statistical freak. Some people predicted that the 1969 trend would

continue upward, an obviously intolerable situation. Railroads,

— Numbers in brackets refer to references listed at the end of this

paper.

182
1 c

Peri 1

i

a 2

' ^^-^

f-'

Rp

1

c

c • c u

rr-n rti

1

' 1

tp

be

per y

;

. , . ._

prior :

=

22

!

O

0) )->

--. ni

i

i

i

t

i

1

1

s- <— «3- la ^O I— V

' 1

Numer of

HM I

i

1

!

( J

1

1

[

1 —

i

1

1 ,

1

1

UJ

ID

Cu

—J

_1LU

LH

a:

<£

LO

LU

a:

<_) CM

:d

a.Q U.

<: O uu

1/1 u.

LU

q; O 1— a a.

LU

CQ a s: LU o <_! o a

(y1 LU

(/I < LU

Qi o _l U.

<c a

1

1

REo

av3A a3d S3SV3 io y3awnN

183
shippers, tank car builder-owners, and government agencies all were

anxious to organize a program to reverse the trend. There emerged a cooperative industry project under an agreement between the Association

of American Railroads (AAR) and five major tank car builders acting

through the Railway Progress Institute (RPI). Policy direction was furnished by a steering committee called the Project Review Committee

comprised of high level representatives of the tank car companies, the

AAR and the railroads.

The project has been administered by Dr. William J. Harris, Jr., Vice

President, AAR Research and Test Department. It is directed technically

by Earl A. Phillips, Project Director, who is assisted by L. L. Olson

of the AAR Technical Center in the capacity of Deputy Project Director.

The project began on March 30, 1970. It has been supported by contributed funds and manpower from the AAR and the tank car companies through

the RPI. Funds and manpower are contributed on a 10:3 and 5:2 ratio,

respectively, by RPI:AAR.

A total of 30 man-years of effort has been expended through 1980.

Project costs, including the value of this manpower, have been over 4

million dollars. The Federal Railroad Administration (FRA) of the

U.S. Department of Transportation (DOT) also has conducted substantial

research in the area of tank car safety, and test programs in many areas were carried out cooperatively between the project and the FRA.

IV. 'PROJECT OBJECTIVE

The project objective is to seek means to improve tank car safety in

accidents. More specifically, it is to develop, through study, tests,

and research, improved knowledge of the factors that cause punctures,

ruptures, and rocketing of tank car tanks in accidents; and to develop,

through the use of this knowledge, practical and proven means to reduce

the probability of these events.

V. PROJECT SCOPE

The project scope covers only tank car behavior during the accident

period as influenced by the associated mechanical and thermal environment.

Importantly, the scope does not include the initial cause of an accident

unless a tank car tank, or a component peculiar to a tank car, is

responsible. Thus, the failure of a tank car wheel, which is like all

other freight car wheels, is outside the project scope. This exclusion

was natural since research on accident prevention is a much broader

activity, being the continued responsibility of the railroads, the AAR,

the FRA, and the supply industry. Post accident handling and cleanup

activity is also outside the scope.

184
VI. PROJECT PHASES AND REPORTS

Project technical activity has been divided into 18 phases. Forty-two

technical reports have been issued on completed studies in specific

areas. These are listed at the end of this paper and will be referenced

as appropriate.

Report distribution has been widespread with copies being sent to

approximately 160 recipients, including personnel of railroads, the AAR,

various shipper oriented trade associations, and United States and

Canadian government agencies concerned with rail transportation.

VII. RESULTS OF RESEARCH

Phase 01 - Accident Data Collection

Beginning with the year 1965, every known accident in which a tank car

was damaged has been logged into a computerized data base. The procedures used in this activity are described in {16}. This is an ongoing

activity, currently being carried out by a staff of two full-time and

four part-time people.

The data, all of which are treated proprietary, are collected from many

sources, including:

The AAR Bureau of Explosives

The Federal Railroad Administration

(Rail Equipment Incident Report, Form FRA F 6180-54)

(Office of Safety, Accident Investigation Reports)

Materials Transportation Bureau

(Hazardous Materials Incident Reports, DOT F 5800.1)

National Transportation Safety Board

Canadian Transport Commission

Railroads

Tank Car Owner-Builders

Tank Car Owner-Shippers

Chlorine Institute

Chemical Manufacturers Association

American Petroleum Institute

Compressed Gas Association

National LP Gas Association

For the period 1965 through March, 1980, over 18,000 tank cars were

damaged in accidents. One out of seven lost lading. A general breakdown of the data is shown in Figure 2.

Phase 02 - Accident Data Analysis

The analysis of the accident data is handled under this Phase. Different types of analyses have been made throughout the project studies as various needs arose.

185
oo

Ol tn 10 cn B

CM <o CO om

ITS o

<u

Q

a

crc 10 Q T3

<0 (U _1 i.

4-> u. o o

_l 1— oZ inm

J= o

4-> _l

IT) c

01 -r-

(0 <T3 E —1

nJ Oo • O fO ^

_J o ^ OJ <M +J So o cs 0) o to

cr. c

CO ^c

<u3 -(-> Q O

(0

</» Q.

S- t-i 3

+J

O

Q-H- 3 C Ol

(0 (/) £ 3

[— rtJ

O

O CO <u

i- <u o c s o

a.o

H- </» Ol T3 C

I— <I> TCO fO 4J E •-- to Lu Q

"O CO

0) E C71 o cr> O «=

nj 4-> •<- CM E +-> +-> ro O O CO -r10

O 3

Ol •(-> OJ O

I/)

Pur.

•O 1 <u ^ to

csj fO nj c E +J

03 -.-> E

LO

01

i_3

<o +J

<uO

a:

Pun oCO

en

a:o O>

CO

C3

>-

•a: r3z

<c-3ao

a:

LO

a.a:

a:

ino

186
Cost-effectiveness was important early in the program since there were

a large number of solutions to evaluate and compare. At that time,

dollar losses incurred by the railroads due to lading loss from the tank

cars were determined for each accident. These losses included the cost

of the lading lost and the costs of damage to other equipment, and to

society, caused by the lading loss. The losses were catagorized by the

specific events which caused them; e.g. head puncture, fire induced

rupture, etc. From these, the potential values of design solutions were

determined.

During the first two years of the project, this type analysis was carried out for all cars which lost lading in accidents over the 6 year

period 1965-1970 {10} {18}. Some dollar losses were found for which the

cause, the class of car involved, or both, were unknown. These were

included by prorating them over all known causes and classes of cars.

These losses were then converted to "benefit" values of solutions. The

philosophy used was that the dollar expenditure which could be justified

for a design solution was the "present value" of all future savings

which would be realized by its application. The accident spectrum of

the future was assumed to be similar to that of the past.

1 / Head punctures of 112A(n4A)— cars can be used to illustrate the methodology. These accounted for losses of about 4 million dollars over the

6 year period. There was an average of 12,000 such cars in service over

this period, so the loss per car per year was 4,000,000/6(12000) = $55.

For a solution having an expected life of 30 years, and assuming a 10%

rate of return (reasonable in 1972), the present value of the $55 per

year stream of payments, using accounting principles, is $527. This is

the justifiable expenditure for the solution if it is 100% effective.

Present values of other solutions were developed in similar fashion.

The results are shown in Table I, from {22}. These numbers are out of

date today, but in 1972 they served as a basis for establishing

priorities. As seen, head shielding, shell shielding, and thermal

shielding of 112A(114A) cars headed the list.

To carry the head shield example further, from a detailed review of

accident and test data, it was estimated that a 5' wide x 4' high x J^" thick steel head shield would have prevented one-half of all past head

punctures on 112A(114A) cars. The actual estimated benefit of such a shield is then $527/2 = $264. The estimated cost of the shield was

$474, so it was not considered cost-effective.

- The 112A car is a "pressure" car that typically carries anhydrous

ammonia and liquified flammable compressed gases. The 114A car is

essentially the same except for variations in fittings.

187
E O • 3 >v O < <-> a)

U — vfl > o 3 n:

OJ >t- o >-

(/) O t/l^

r- o

••- 3 r-

<S 1 >,

r— O 0)

4J > O

0) 4J <-> OJ O <T) •--

188
These were 1972 benefit and cost values. As time went on, circumstances

changed, and head shields became justified. They now have been installed on over 20,000 112A(114A) cars.

Recent accident data have been reviewed to quantify the safety improvement resulting from the application of these "shields" on 112A(114A)

cars {44}. Dollar losses were not considered; instead, only the

frequency of lading loss cases was developed. The results (including

shell punctures and fire induced ruptures) are shown in Figure 1. An

average of 22 cases per year occurred over the period 1965 to 1978.

The drop-off beginning in 1978 is evident as the retrofit program began.

The effectiveness of the head shield appears to be significantly higher

than predicted, although it is still too early to accurately quantify

the improvement.

Phase 03 - Tank Car Steels

The objective of Phase 03 was to seek improvements in steels which

would reduce the probability of punctures and ruptures. Of primary

concern were steel toughness and strength properties at various temperatures.

A large amount of test work was conducted on currently used steels, on steel samples removed from tank cars involved in accidents, and on steels used on older cars which were being scrapped. The object was to

characterize their physical, chemical, metallurgical, and fracture

toughness properties. The latter were determined using the Charpy

v-notch test, drop weight tear test, dynamic tear test and the NOT drop

weight test. The results are published in {33}.

Materials for the most part met specifications. Variations beyond

specified ranges in chemistry and tensile properties were few. In the case of accident samples, differences in mechanical properties were

largely attributed to alterations caused by the accident. None of the

above variations was believed to be a factor in the cause or extent of

damage in any of the accidents.

Figure 3 from {32} summarizes one fracture mechanics aspect of the

study. This figure applies to TC-128-B steel which has been commonly

used for 112A(114A) cars since mid-1960. The vapor pressure of the

liquified gases which these cars carry is a function of temperature;

hence, the hoop stress in these cars is a function of temperature.

This hoop stress- temperature relationship is shown in Figure 3 for propane, ammonia, and vinyl chloride. Based on dynamic tear tests, the

50% shear fracture temperature was determined for a number of specimens

in the "normal ized-stress-rel ieved" and the "as-rolled-stress-relieved"

condition. This temperature point is called the "Yield Criteria" (YC).

At this temperature, the steel is sufficiently resistant to fracture

to require yield level stresses for continued propagation of a through

crack. Above this temperature, the fracture is stable and requires

189
(0co

mm

01 T3 eS •r-S- 01 o C

(O x:

Q- ^ o o

iX

D. \\ c

>-

s-

+-> (O

S-

(UQ-e

i-3

••-> O

1-

cu oLO o

CVJ oIxJ DC<;

i~i 00

Si a; o <c

c_j

Q.. z;cC1— o t—t

t—

eH 00 r UJ UJ q: q; 3>

1— UJ o a: < o rD

1— U_

cC

QJ q: UJ

i. LU hCC

4-> s: CJ3

rtJ QJ >=C s- 1— Q.

<u

O

Q. 1 q: E Q.

CU OO

I— o LU hq:1—OO UJ

O-o r> o cr

3: Ul

C£. 1 00 1 00

UJ

a. CO 1—

OO UJ

q; o ZD 1— C3

»—* u.

IS)! 'ss9j:is dooH

190
higher than yield (plastic) stresses to propagate. Nil Ductility

Transition (NDT) temperatures were determined from drop weight tests.

At temperatures below NDT, fractures are highly brittle. The actual

YC and NDT points for the specimens tested are shown in Figure 3.

The YC points are plotted at the yield stress and the NDT points over

a stress range of 5 to 8 psi, below which fractures will not propagate.

For as-rolled, stress relieved steels falling in the high transition

temperature range, the figure shows that fractures will not propagate

in a brittle manner. Below BO'^F the hoop stress is too low for brittle

fracture propagation. A very small probability of brittle fracture

exists around 50°F. These conclusions relate only to pressure induced

hoop stresses. If large areas of high stresses are temporarily created

in an accident by external mechanical forces, the probability of brittle

fracture is increased if the tank is sufficiently cold. The accident

data confirm, however, that this is a rare occurrence. In summary, the

detailed study of TC-128-B steel showed it to be an optimum product for

the service, refs. {32} {33}.

Phase 04 - Literature Review

Background experience and literature in the technical areas of interest

under the Project has been continually under review. A reference

library was established and is being maintained under this Phase.

Phase 05 - Tank Car Heads

Phase 05 was devoted to the development of a method to reduct the frequency of head punctures. The first activity was a conceptual design

study carried out under contract to the FRA (Phase 13 of the Project).

The study concluded that a 5' wide x 4' high x hi' thick steel plate

spaced in front of the tank car head was the most promising design to

progress in a test program.

Initial tests were conducted on old riveted tank cars. The heads on these cars were impacted with a standard "E" coupler mounted in elevated

position on a specially built "ram" car. Forty-two impacts were con- ducted on 21 cars. Variables studied were car weight, outage, internal

pressure, impact height, number of backup cars, and the protection

offered by standard insulation and then by the ^^" thick head shield.

Next, two series of 1/5 scale tests were conducted. The objective of

the first series was to determine if a difference in puncture vulnerability existed between two different designs of the head-to-sill con- nection on stub sill tank cars. The two lefthand sketches in Figure 4

show one design, and the two righthand sketches show the other. Three

backup cars were coupled behind the test car in each test. Thirty-two

tests were conducted on both ends of 9 non-pressure tank cars and 9

pressure tank cars. The results (scaled up to full scale) are shown in

Figure 4. They indicate that the design incorporating the reinforcing

shoe between the head and sill is slightly more vulnerable (lower

191
192
puncture speeds), but it was concluded that the difference was not

significant.

The objective of the second series was to study head punctures of

n2A340Wl/ pressure cars. These 1/5 scale tests were useful in re- ducing the scope of the final, and expensive, full scale tests.

Thirty-two tests were conducted covering several variables. The

results are plotted in Figure 5, from {17}. As seen, vulnerability

increases with increasing internal pressure, decreasing head thickness, and decreasing head material tensile strength. With the

(scaled down) J^" thick head shield, impacts up to 17.5 mph produced

no puncture. A final impact was conducted using a 26% heavier ram

car. At 17.8 mph, no head puncture occurred. With the standard

ram car, and assuming momentum governs, this would be equivalent to

a 22.4 mph impact, which is the top point plotted in Figure 5.

The final test program employed two identical full size 33,500 gallon

112A340W cars, one without head shields and the other equipped with ^" steel head shields at each end. Each car was loaded with water and

pressurized to 100 psig. Each was backed up by three loaded cars. The

results also are plotted in Figure 5. On the car without a head shield,

a 9.3 mph impact produced a 9 inch dent in the head, but no puncture.

In a second test on the other end of the car, the head was punctured at

12.7 mph. On the car with the head shield, no puncture occurred at

15.5 mph. It is emphasized that in a derailment these impact speeds

are not train speeds, but are the closing speeds between cars. On the

other hand, they are the actual speeds in a switchyard where one car is

stationary. The second (higher speed) test planned for the head shield

on the other end of the car could not be carried out because the ram

car was damaged beyond repair in the 15.5 mph test. Thus, the improvement offered by the shield could not be quantified, but it was clear

from all tests that it was significant.

All 112A(114A) cars which carry hazardous liquified compressed gases now

have been retrofitted with the thick steel head shield. It can be

the form of a trapezoid spaced in front of the lower half of the tank

head; or, if the car has a blanket type thermal shield (see Phase 11),

it can be a V thick steel jacket head covering the insulation. The i^" steel jacket design also now is required on new 105A cars carrying

flammable liquified compressed gases and ethylene oxide (see Phase 17).

Phase 06 - Safety Valve Liquid Discharge Capacity

When a tank car carrying liquified compressed gas is heated in a fire,

its contents can expand to where the tank car becomes liquid-full. The

safety valve must then maintain safe tank pressure by momentarily discharging liquid. It may also be called upon to discharge liquid in the

event the tank is overturned and exposed to fire. -

This is a 112A car that has a test pressure of 340 psig.

193
PLSiiMS peaiH Lsa^iS ,,2/L

<:o1/1

L. 01 3 C

I/) ^ wi emu u

Ol T- 1X3 -r- i- CO O) JZ

o. clh: I—

<u +-• s- o

r3 c

+-> 3 o Q. c

3 O

Q. C

M II 0 •

Co

01

+->

<:o

oI—

a.

<_3

le.LMS pe^H L^^:^S „2/l M^tiM

!

(Si Ooooz)

(Si OOOOS)

O CO o --^ 1— ID

O ^ I— CO

D-S82-V

-1_

o = O I—

VO O r— o \ ^— CO

o ca or— ID

CO

IX>

CO—

.

ID

00 <JD

Ljduj 'peads :tDeduii

194
As in other pressure vessel codes, the tank car specifications require

that safety valves be sized on the basis of vapor discharge. There

being no firm data on liquid discharge capacities, this Phase was established with the objective of determining such capacities.

A special 20,000 gallon test tank was furnished by the Project and installed at Edwards Air Force Base in California. Tests were conducted

by the Air Force Rocket Propulsion Laboratory under contract to the FRA.

Products tested were water, nitrogen, and propane. Means were provided

for mounting the safety valve at both the top and bottom of the tank to

measure vapor and liquid discharges. These were "blow-down' tests.

Tank pressures were raised above the safety valve setting, then released

to the safety valve which discharged until the pressure dropped to the

valve's reseat setting.

There are two manufacturers of safety valves for 112A(114A) tank cars. Both valves exceeded the specification requirements for vapor discharge.

Problems with the test set-up led to difficulties in assessing their

liquid discharge capabilities.

P hase 07 - Safety Relief Device - General

This Phase covered all types of safety relief devices on all classes of

tank cars. Its objective was to develop design changes to assure safer

containment, or safer release, of hazardous products in accidents.

Activity did not progress beyond initial planning since the evidence

did not show that current devices were deficient.

Phase 08 - Reduced Scale Model Studies

Consideration was given to conducting scale model derailments to study

the influence of variables such as truck securement, coupler types,

train makeup, and train speed. Because there was no easy way to scale

gravity, this approach was abandoned, and a computer simulation was developed.

The computer simulation provided car motions, speeds, forces, and accelerations in derailments. Simple F = ma was the underlying theory.

Following successful validation of the computer model by comparison with

an actual derailment, a number of results were obtained. Some are shown

in Figure 6. This parametric study used as a base case:

0 A consist moving at 40 mph with 61 cars trailing the first

car derailed.

0 All cars identical --

43' truck centers

160,000 lbs. gross weight on rail

195
196
E couplers

Cast iron brake shoes

0 Coefficient of friction between the derailing (sliding)

cars and the ground = 1.0

This base case was selected from a statistical averaging of many

derailments. In this base case, 17 cars derailed, the duration of the

derailment was 26 seconds, and coupler forces up to 473,000 pounds

were created.

The results, from {12}, showed:

0 The influence of braking on the cars approaching the derailment

site was significant, but no great reduction in the number of

derailed cars could be achieved with any practical change in

the braking system. For example, 17 cars derailed in the base case with emergency braking applied in the normal manner. As

shown in Figure 6, 24 cars derailed with no braking. With

emergency braking applied with a braking force twice that

achievable with cast iron, 14 cars derailed. With emergency

braking applied instantaneously to all cars (not shown in

Figure 6), 16 cars derailed. Finally, as a limiting case

(also not shown in Figure 6), if braking was sufficient to cause all cars to slide at the instant of derailment, 10 cars derailed.

0 The number of cars derailed increased significantly with an increase in the number of cars trailing the first derailed

car (Figure 6) . .

0 An increase in ground friction decreased the number of cars derailed (Figure 6)

.

0 The number of cars derailed was almost inversely proportional

to car length. This is primarily because of the large rotational inertia of the longer cars and the resulting ability to

absorb more energy through ground friction.

0 Distribution of car weight also had a significant effect on the derailment. With heavy oncoming cars followed by light

ones, and maintaining the same total weight as in the base

case, fewer cars were derailed (Figure 6). When reversing the

order of cars, considerably more were derailed.

0 When mixed cars were in the consist, the derailments were more

unsymmetrical and more spread out.

0 The parameters which cause differences between passenger and

freight train derailments have never been fully understood.

197
In cases run with the same train speed and total mass, the

passenger train experienced fewer derailed cars. This effect

was primarily due to car length.

^

0 The effect of train speed was significant (Figure 6), with

the number of derailing cars increasing in greater ratio than

train speed.

Phase 09 - Design Study - Tanks, Attachments, and Fittings

Phase 09 concerns tank shells (portion between the heads), and attachments and fittings.

Dollar losses due to shell punctures of 112A(114A) cars have been high

(Table I). Several solutions were examined {22}, such as thickening

the shell, adding a protective steel jacket, and increasing the

strength of the shell material. None was cost-effective. Shell punctures generally have been very severe and are caused by a variety of

complex circumstances (compared to head punctures which predominantly

are caused by couplers on adjacent cars). As a result, the effectiveness of solutions was difficult to estimate, and probably would be

very low for any.

The most vulnerable fitting was found to be the bottom outlet on non- insulated non pressure stub sill cars (Table I). Stub sill cars do not

have the full length underframe which offers some protection to the

outlet. Sumps on 112A and bottom outlets on 114A cars also were re- sponsible for large losses. Cost-effectiveness studies were made for numerous solutions in 1973-74 {24}, {27}, and several recommendations

resulted. Subsequently, the "benefit" values of solutions increased

significantly when new EPA spill laws appeared. The AAR Tank Car Committee has now mandated bottom fitting protection on all new cars and

on a large number of existing cars. Protective "skids" or recessed

fittings are required. Because of the potential for fatigue damaging

stresses to occur in the tank shell adjacent to a welded-on skid, an extensive series of road and non-destructive impact tests were con- ducted to help develop design criteria {41}. Destructive impact tests

on cars with several different skid designs also were run {41 A}.

Phase 10 - Design Study, Non-Tank Portion of Car

Couplers were of prime interest under this Phase. In 1970, the type

"F" interlocking coupler was required on all new tank cars. Unfortunately, it has a significant disadvantage in that it does not always

protect the car on which it is installed against head punctures. It

has only a bottom shelf which prevents an adjacent coupler from disengaging downward, but not upward (unless the other coupler is an F coupler). Thus, when cars bounce and disengage in a derailment, the

chances are over 50% that the adjacent coupler will disengage upward

and puncture the F coupler equipped car. Accident data confirmed this.

198
For example, during one 11 month period, 5 cars equipped with F couplers incurred head punctures, one at both ends.

Project effort was directed toward the "E" coupler with a top and

bottom shelf and the "F" coupler with a top shelf. A sketch of a type

E coupler is shown in Figure 7. Both of these couplers can restrict

separation in either direction when mated to any type coupler. Accordingly, they will protect both adjacent cars and cars on which they are

installed.

Following a successful service trial of 225 carsets of E shelf couplers

and 100 carsets of F top shelf couplers, the following a number of

tests {11}, analyses {19}, and accident experiences {25}, {28}, the

Project recommended that all new tank cars be equipped with the E shelf

coupler and all existing 112A(114A) cars be retrofitted with the E or

F shelf coupler, as applicable. Changes in regulations implementing

these recommendations did not occur until the shelf coupler effectiveness was further proven in a series of destructive impact tests con- ducted un Phase 15.

Phase 11 - Thermal Effects Study

The whole thermal question, including fire environment and thermally

induced stresses, was covered under this phase.

Early in the program a theoretical study was made on the effect of fire

on n2A(114A) cars {5}. This demonstrated the sequence of events from

fire initiation to tank rupture.

The major activity was a search for a practical heat shield material,

such as an ablative or intumescent coating, or a high temperature re- sistant insulative material, that could be applied to 112A(114A) cars.

As Table I shows, fire induced ruptures of these cars led to the highest

dollar losses of all over the 6 year base period. Many sample materials were studies in a laboratory fire test apparatus designed for initial

screening {15}. They were tested on 6" diameter by 5/8" thick steel

discs representing the tank shell. Thermocouples on the backside of

the discs measured the temperature rise of the steel.

Two of the most promising materials were selected for application to

1/5 scale tank cars furnished by the Project for fire tests at the

White Sands Missile Range in New Mexico. The tests were conducted by

the U.S. Army Ballistics Research Laboratory (BRL) under contract to

the FRA. The objectives were to ascertain some of the properties of

fires which were not yet well defined and to prepare for subsequent

full scale tests. These 1/5 scale tests are discussed in {14} and

{26}.

Next, two full scale 33,500 gallon 112A340W cars also furnished by the

Project, were tested in fully enveloping JP-4 fueled fires {31}. One

199
FIGURE 7 -- TYPE "E" TOP AND BOTTOM SHELF COUPLER

200
car was bare (standard white alkyd paint only) and the other was insulated with approximately 1/8" of a sprayed-on thermal coating. Both

cars were filled with propane to standard loading conditions., The

safety valve start-to-discharge pressure setting was 280.5 psig,

standard for cars of this type. The temperature- time curves for two

points on the top of each tank are plotted in Figure 8 from ref.' {34}.

In the bare tank test, rupture occurred 24.6 minutes after ignition.

The tank initially carried 31,900 gallons of propane, and more than

half of this had been discharged through the safety valve prior to

rupture. The tank pressure rose to 347 psig 17.5 minutes after ignition, then dropped off, ending at 334 psig at rupture. 1/ Considering

that this fire was far more extreme than the typical tank car accident

fire, the safety valve performance was considered quite adequate, maintaining a reasonable pressure and yielding a discharge rate closely

approximating 100% of the theoretical maximum efflux rate. As expected,

the fracture origin was at the top of the tank over the vapor space, and

metallurgical analysis of the steel at the precise origin indicated that

it had reached a temperature in the range 1050-1100 F. This time-torupture and temperature range at rupture is shown as the black rec- tangle labelled "H" in Figure 8.

Using the simple hoop stress formula, and using the ultimate tensile

strength of the steel determined from high temperature tensile tests, the

pressure at rupture was calculated to be in the range 301-412 psig.

This "indirect" approach of estimating pressure at rupture correlated

fainly well with the measured pressure. This metallurgical technique

was used to determine the tank pressure at rupture and the steel temperature at the rupture origin in seven acciderit cases. The pressures

at rupture in these cases were not significantly high (above the safety

valve setting). These are shown in Figure 8 as rectangles A through G.

The times-to-rupture for many other accident cases were known, but

steel samples were not available for determining maximum temperatures.

These cases are shown as vertical lines in Figure 8.

In the coated tank test, rupture occurred after 93 minutes. At that

time the tank was nearly empty, and the rupture was considerably less

violent than in the first tests, most of the propane having been discharged. Pressures were less than in the first test. Again, the temperature of the steel at the rupture origin was determined metal lurgically, this time as being between 1100°F and 1160°F. This case is

shown in Figure 8 as rectangle "I".

In addition to these all enveloping "pool" fire tests, the "torch" type

fire was studied. This is a highly conventive fire involving local impingement as compared to the highly radiative pool fire. The torch fire

studies were conducted by the BRL at the DOT Test Center in Pueblo,

Colorado and are discussed in {36}.

- These pressures are considerably below the car's 850 psi design

burst pressure.

201
202
Based on these pool and torch fire tests a regulation was issued

(HM-144) which required thermal shielding on all new and existing

112A(114A) cars carrying flammable gas. Most cars have been shielded

with a high temperature blanket type insulation covered with a protective steel jacket, but a substantial number have been covered with a sprayed-on coating.

The Pueblo torch fire apparatus ultimately was rendered capable of producing a fire of near pool fire characteristics and has been used to

qualify thermal shield systems under both torch and pool fires. The

two curves representing these qualification requirements are shown in

Figure 8.

The study of recent accident data {44} shows that these thermal shields

have led to a significant reduction in fire induced ruptures. This is

predictable from Figure 8 since the two HM-144 qualification curves

are far below and to the right of the accident cases. As seen, if any

ruptures do occur, they most likely would be caused by a sustained

torch fire. Of course, any car that loses its thermal shield during

the derailment also will be vulnerable.

Phase 12 - Vessel Failure Research .

This has been the basic research phase related to tank ruptures. Its

objective was to explain fundamentally a number of phenomena asso- ciated with the catastrophic type rupture. This includes brittle

fracture, the hurling (rocketing) of tank tub sections, and the characteristic crack propagation patterns which lead to flattened center

sheets and circumferentially separated end tubs.

Battelle Memorial Institute was engaged to conduct this research. The

final report is given in' {20}.

Based on the Phase 03 tank car steel tests, detailed examinations of

dozens of tank cars which ruptured in accidents' {6}, and basic fracture

mechanics theory, conclusions were reached as to the potential benefits

of various changes in steel properties and fabrication techniques.

These included increasing thickness and strength, normalizing, reducing

grain size, and cross rolling or changing rolling direction.

None of these changes was found to be effective, and all were extremely

cost-ineffective. Increased toughness could not be justified since

only a few accidents involved brittle fracture, and in most the destructive forces were so great that product release probably would have

occurred in any event.

Considerable theory was developed on critical crack lengths (below

which crack propagation will arrest). The critical crack lengths for

tank car shells and heads were very large under most accident condi203
tions. This explains why so many punctures remained local. In the case of thermally overheated tanks, the study showed that "practical"

changes in material properties and thickness, and in tank diameter,

would have little effect on the critical crack lengths; therefore, they

would not be effective in alleviating the violent rupture problem.

A significant finding was that in every known case of a fire induced

rupture of the flammable compressed gas car, the crack originated in

the vapor space where the steel was overheated. The seven accident

cases and the two test cases labelled A through I in Figure 8 confirm

this. Other accident data also confirmed this {1}, {7}, {9}. High

overpressure caused by inadequate safety valve capacity has not turned

out to be the basic cause of rupture.

Battel le also examined the "rocketing" phenomenon {23}, but no costeffective solution to prevent it was found {20}.

Phase 13 - DOT(FRA) Head Shield Study

This Phase covered the "conceptual" head shield design study carried

out under contract to the FRA, see discussion under Phase 05.

Phase 14 - Stub Sill Tank Car Buckling

Tank shell buckling has occurred inboard of the stub sill termination

on certain designs of non-pressure stub sill cars. The tank of a stub

sill car carries the train loads, and these cases of buckling have

occurred under high compressive train action and sometimes during

switchyard impacts. The problem has been limited to empty cars. When

stub sill cars are loaded, the tensile stress in the bottom fibers of

the tank produced by the lading weight is sufficient to offset the

otherwise critical compressive stress.

The object of this Phase was to determine what design and test loads

should be specified for stub sill cars to assure that their resistance

to buckling is at least as good as that of other freight cars.

Tests involved static squeeze and dynamic impacts of 10 stub sill cars of different design, 5 of which experienced a history of buckling

and 5 of which were of new and improved design. Approximately 80

strain gage rosettes were employed on each car.

The results and conclusions from this extensive test program are given

in {38}. While interesting from the standpoint of experimental stress

analysis techniques, it will suffice here to simply reference the

report.

204
Phase 15 - Switchyard Impact Tests

Several catastrophic switchyard accidents involving tank car head

punctures have occurred. These constitute the third accident scenario

given at the beginning of this report. They involve the striking of a light empty freight car by one or more loaded cars. In some cases the

lead loaded car has been a tank car, and it is punctured by the coupler

of the empty car. In other cases, the empty car is driven into and

punctures a loaded tank car standing ahead of it.

To study these accidents, a full scale test program was undertaken in

cooperation with the FRA and carried out at the Pueblo test center.

Single empty hopper cars were impacted by loaded tank cars at destructive speeds and driven into other loaded tank cars. The objective was

to assess the ability of the shelf coupler, the head shield, or both

in combination to prevent punctures in this particular accident scenario.

Results are given in {40} and are summarized herein in Table II. The

last four tests were particularly severe because the number of impacting

cars was increased from 1 to 3. The last test was the severest because

the speed was high (17.1 mph), the spacing "S" was 3.75 ft., an optimum

distance for override , and the internal pressure in the test cars was

125 psig (vs. 100 psig in all other tests).

These Phase 15 tests were considered final proof of the effectiveness of

the head shield, and particularly the shelf coupler, in preventing head

punctures.

Phase 16 - Component Wear Study

Wear rates of various running gear components on tank cars were measured

under this Phase. This had no relationship to tank car behavior in

accidents so is not described in this paper.

Phase 17 - Class 105A Car Study

The 105A tank car is an insulated pressure car. The insulation specifications are based on protecting the commodity from ambient temperature

conditions and not from fire. Class 105A cars are authorized to carry

many of the same products that the (now retrofitted) 112(114) cars are authorized to carry. New 105A cars carrying these products have

recently been required to have the 112(114) car type protection; but

an inconsistency exists with existing cars. The objective of Phase 17

is to assess the significance of the inconsistency.

Initially, a population study and accident data review was carried out

to compare various 105A cars and to compare them with 112A(114A) cars

(before retrofit) {43}. The 105A cars as a group were found to be

significantly less vulnerable to punctures and fire induced ruptures

205
01

. <— (U Q. a

O HI— a; D. a

OJ 0^ Oi

ir> LO in in

CNj ro CO cvj csj

LU UJ UJ

i/^ i/> </> t/>

o o o o

LU uj UJ

T3 T3 T3 -O

m in in

CM csj CO ro

UJ 0) UJ UJ

a\ ir> ^

vo tr> y3

•o -

4-> UJ UJ

oo -

>- z z >- z

U3 ^ O C\J r00 (Tt <T> CO

4

r-JI

— P

Ml

rl

SI

lO VO ^ lO VO lO lO lO lO lO

^ in in in o o o o

00 in r-^ CM ro r- O rco a. o o o o — .— >—

QJOIOIO^O) 0l<U0J0>''~ (JCO) — .— .— I— r- f— .—

E o 1 — ^ 0) -I H

£ I- (O 3

C (J >> <J o o

^1

206
than n2A(n4A) cars. Class 105A cars carrying ethylene oxide ex- perienced a higher rate of fire induced ruptures than other 105A cars. Class 105A chlorine cars were found to perform particularly well, and

105A cars in vinyl chloride service were found to be particularly

vulnerable to head and shell punctures.

In another activity, mechanical impact tests and fire tests were conducted on 2 ft. square and 4 ft. square specimens representing

several common 105A car tank-insulation-steel jacket constructions.

As in other Phases the tests were carried out by the BRL under contract

to the FRA and in cooperation with the Project which furnished the test

specimens. Fire tests were run with the steel jacket bare and then

covered with various thermal coating systems, the concept being

directed toward shielding existing cars. At this time the results have

not been analyzed. Even if cost-effective, it remains to be demonstrated that the coatings will maintain their integrity when applied to

the thin (11 gage) steel jacket.

Phase 18 - Integrity of Damaged Pressure Cars

A risk situation arises when a tank car, particularly a 112A(114A) or

a 105A pressure car, is damaged in an accident but does not release

its lading. The wounded tank suffers a reduction in its burst strength.

If the pressure rises above that which existed at the time of the

accident, it may approach or reach this reduced burst pressure.

Personnel involved in wreck clearing operations can be exposed to great

danger under this condition.

The plan under this Phase is to hydrostatical ly test to burst a number

of wounded tank cars which did not lose lading in accidents. If a correlation can be developed between the reduction in burst pressure

and the type of damage, possibly some guidelines will emerge which

will help protect workers at the scene. Work under this Phase has just

begun.

VIII. CLOSING REMARKS '

>

Major activities have been directed toward reducing risk through design

changes. A number of correlary benefits have emerged from the program.

The effectiveness (and efficiency) of carrying out research on a co- operative basis between the railroads, shippers, tank car builders and

the government has been demonstrated. As new situations or questions

arise, means now are available to promptly study and resolve them. Of

particular interest will be a report to be issued shortly which will

present all of the accident data in the Project files over the 16 year

period 1965 through 1980. These data will be invaluable in analyzing

many risk situations. It is not possible to predict all future uses of

the data, but experience has shown that problem areas do continually

arise. Some are unexpected and result from accidents involving a new

207
phenomenon. For this reason, the collection and analysis of accident

data is being carried out on a continuous basis.

REFERENCES: Following is a chronological list of reports to date by

the RPI-AAR Tank Car Safety Research and Test Project. Copies may be

ordered from:

Mr. J. G. Britton, Executive Director

AAR Technical Center

3140 S. Federal Street

Chicago, Illinois 60616

Prices include mailing costs within the United States.

Ref. T.C.

No. Report No. Ti tl e Date Price

1 RA-01-1-1 Phase 01 Report on Sequence of 8/19/70 $ 2.50

Events Following Crescent City

Derai Iment

RA-03-1-2 Phase 03 Report on Metal lographic

Examination of Specimens Removed

from Sections of Tank Cars in

Crescent City Derailment

RA-01-2-3 Phase 01 Report on Summary of

Ruptured Tank Cars Involved in

Past Accidents (Superseded by

RA-01-2-7)

RA-03-2-4 Phase 03 Report on Metal lographic

Examination of Specimens Removed

from a Section of Tank Car in

South Byron, New York Derailment

RA-1 1-1-5 Phase 11 Report on Effects of

Fire on LPG Tank Cars

RA-1 2-1 -6 Phase 12 Report on Tentative

Tank Car Accident Investigation

Guide (Revised 4/26/73)

RA-01-2-7 Phase 01 Report on Summary of

Ruptured Tank Cars Involved in

Past Accidents (Revised 7/1/72)

10/15/70 $ 2.50

12/4/70

3/10/71 $ 1.20

4/19/71 $ 7.50

4/26/73 $ 1.20

7/1/72 $ 3.80

208
Ref

.

No.

T.C.

Report No.

8 RA-04-1-8

RA-01-3-9

10 RA-02-1-10

n RA-10-1-11

12 RA-08-1-12

13 RA-03-3-13

14 RA-11-2-14

15 RA-11-3-15

16 RA-01-4-16

17 RA-05-1-17

18 RA-02-2-18

Title

Phase 04 Report Review of

Literature and Related

Experience

Phase 01 Report on Sequence of

Events Following Houston,

Texas Derailment

Phase 02 Report on Dollar Loss

Due to Exposure of Loaded Tank

Cars to Fire - 1965 Thru 1970

Phase 10 Report on Determination

of Moment Characteristics in a Horizontal Plane of Mated

Combinations of Types "E" and

"F" Couplers

Phase 08 Report on Computer

Derailment Study

Phase 03 Data Display Report

on Results of Tests on Mill

Plate Samples and Samples

Removed from Tank Cars Involved

in Accidents (Superseded by

RA-03-5-33)

Phase 11 Report on Analysis

of 1/5 Scale Fire Test Data

Phase 11 Preliminary Report

on Laboratory Fire Test

Apparatus for Evaluating

Thermal Shield Materials

Final Phase 01 Report on Accident Review

Final Phase 05 Report on Tank

Car Head Study

Final Phase 02 Report on Accident Data Analysis

Date Price

7/30/71 $ 5.00

10/19/71 $ 1.20

2/23/72 $ 2.50

2/15/72 $ 1.20

2/17/72 $ 3.80

4/19/72 $ 6.20

4/12/72 $ 2.50

5/24/72 $ 3.80

6/30/72 $ 3.80

7/14/72 $ 6.20

8/14/72 $12.50

209
Ref.

No.

19

20

21

22

23

26

27

29

30

31

32

Report No.

RA-10-2-19

RA- 12-2-20

Not Issued

RA-00-1-22

RA-1 2-2-23

24 RA-09-1-24

25 RA-10-3-25

RA-11-5-26

RA-09-2-27

28 RA-1 0-4-28

RA-05-2-29

RA-10-5-30

RA-11-6-31

RA-03-4-32

Title

Final Phase 10 Report on Couplers and Truck Securement

Final Phase 12 Report on Tank

Car Fracture Analysis

Overall Project Summary Report

Phase 12 Report on Analysis of

Tank Car Tub Rocketing in

Accidents

Final Phase 09 Report on Tanks,

Fittings and Attachments in the

Mech. Environment of Accidents

Phase 10 Report on July 1, 1973

Accident Involving Type "E" Top

and Bottom Shelf Couplers

Phase 11 Report on Analysis of

1/5 Scale Fire Tests

Final Report on Phase 09

Extension Study of Tank Car

Bottom Fittings

Phase 10 Report on February 9,

1974 Accident, Involving Type

"E" Top and Bottom Shelf Couplers

Phase 05 Report on June 9, 1974

Accident Involving Head Shields

Phase 10 Report on Development

of Shelf Couplers

Phase 11 Report on Full Scale

Fire Tests

Phase 03 Report on Fracture

Properties of Tank Car Steels - Characterization and Analysis

Date Price

8/14/72 $ 2.50

9/29/72 $10.00

10/6/72 $ 3.80

12/13/72 $ 2.50

2/15/73 $ 5.00

11/16/73 $ 2.50

12/12/73 $ 5.00

5/31/74 $11.20

4/22/74 $ 5.00

8/28/74 $ 1.20

9/6/74 $ 5.70

12/12/75 $11.00

8/20/75 $ 7.50

210
1

Ref

.

No.

37

38

T.C.

Report No,

33 RA-03-5-33

34 RA-1 1-7-34

35 RA-05-3-35

36 RA-1 1-8-36

Not Issued

RA-14-1-38

39 RA-11-9-39

40 RA-1 5-1 -40

41 RA-09-4-41

Title

Final Phase 03 Report - Material

Study on Steels Used in Current

and Former Tank Car Construction

and From Cars Involved in

Accidents

Phase 11 Report on Specifications

for Thermal Shield Systems on DOT 112A(n4A) Tank Cars

Phase 05 Report on Head Shield

Fatigue Tests

Technical Progress Reports

Nos . 1 through 31

Evaluation of RPI-AAR and

BRL Torch Fire Tests of Tank

Car Insulations

Final Phase 14 Report on Stub

Sill Buckling Study

Phase n Report on Inspections

of Insulation-Jacket Type

Thermal Shields on Tank Cars

in Accelerated Life Tests

Phase 15 Report on Switchyard

Impact Tests

Phase 09 Final Report on Bottom Fittings Protection

Test Program

41A RA-09-4-41A Addendum to Phase 09 Final

Report on Bottom Fittings

Protection Test Program

42 RA-09-5-42 Study of Bottom Discontinuity

Damage on Non-Pressure Stub

Sill Tank Cars in Derailments

During 1977 and 1978

Date Price

8/21/75 $20.00

1/23/76 $11.20

11/10/75 $ 4.00

5/28/70

Thru

6/6/75

$1.00

each

9/9/76 $ 2.00

7/29/77 $20.00

1/13/78 $ 2.00

8/2/78 $ 5.00

12/22/78 $ 5.00

4/23/79 $ 4.00

2/14/80 $ 5.00

211
Ref

.

No. Report No. Title Date Price

43 RA-17-1-43 Phase 17 Report on Study of 8/22/80 $ 4.00

Class 105A Tank Cars

44 RA-02-3-44 Phase 02 Report on Effectiveness 5/15/81

on Shelf Couplers, Head Shields

and Therrr.al Shields

212
PERFORMANCE TESTING TO

REDUCE LOSS AND DAMAGE

William A. Vickerman

Association of American Railroads

59 E. Van Buren Street

Chicago, Illinois 60602

W. D. Godshall

Forest Products Laboratory

P. 0. Box 5130

Madison, Wisconsin 53705

Abstract: Performance testing of shipping containers can help reduce

loss and damage by increasing the efficiency of package development. The

cumulative effect of successive handlings can be predicted in the

laboratory. This insures a higher probability of success during test

shipments in the field.

In 1980 damage claims to railroads amounted to $324.5 million. The staff

of the Damage Prevention Section of the Association of American

Railroads is working to reduce these claims through educational

programs, field studies, field testing, and laboratory evaluations.

Educational programs for various commodities are prepared after

extensive field studies. Field tests and laboratory evaluations try to

determine the best methods of packaging, unitizing, loading, and bracing

for rail shipment.

When conducting field studies, we take special note to handling of

products prior to rail shipment. A slightly damaged product placed in a rail car may be further damaged by normal forces occurring in transportation. For example a fatigued container in the bottom layer could result

in breakdown of part of a load in a rail car. The result could be further

damage to adjoining containers.

Impact tests and field tests are conducted on fully loaded rail cars. Impact tests approximate the shocks a rail car may experience while

moving through several rail yards. Up to forty of these tests on closed

cars are conducted each year by the AAR. Fifty percent of the impact

tests are successful and move to the field test stage. Field testing

eliminates another fifty percent leaving approximately ten successful

loading and bracing methods for publication.

Tests for new unitizing and packaging methods follow similar procedures

for approval. Extensive field testing is conducted to determine if a method is suitable for rail shipment. The Uniform Classification Committee is responsible for these evaluations. They have done an out213
standing job of monitoring the test permit packages. For the benefit of

the rail industry and their customers we constantly look at methods to

improve evaluations of packages. Two methods are emerging as a means of

improvement.

The first is the establishment of a standard packaging code so that rail

inspectors can include package conditions in their claim report. These

conditions would be included with claim data submitted to data systems of

the railroads. Damage to products could then be sorted by package type

and damage. Presently a simplified packaging code is optional for claim

reporting. The result is very limited reporting of package condition. We

hope that in the future more extensive use will be made of this optional

packaging code.

The second means of improved evaluation of damage to shipping containers

is performance testing. Performance tests can be used to simulate forces

occurring in the distribution environment. Railroads have long

recognized the importance of performance testing. In 1919, the U.S.

Railroad Administration met at the Forest Products Laboratory in

Madison, Wisconsin to establish standards for containers based on revolving drum tests. The experiences of World War I had shown the need

for performance test procedures to supplement material specifications.

Again, following World War II, the shortcomings of material

specifications were noted and renewed efforts were made to develop

useful preshipment performance tests. In 1948, the National Safe

Transit Committee (NST) was formed and the pre-shipment test procedures

were developed. These procedures are probably the most widely used of

any at this time.

During the past eight years the Committee D-10, on Packaging, of the

American Society for Testing and Materials (ASTM) has been developing a performance test for shipping containers. At the AAR Container

Laboratory in Chicago we have extensively evaluated this test procedure.

By adjusting test sequences and levels we were able to approximate

shipping damage in many areas. We have found the test most useful for

comparative testing purposes. For these reasons we believe that

performance testing will be an important supplement to material

specification tests.

For many years, all of our standards for shipping containers have been

based on specifications of materials. The carrier shipping rules are based almost entirely on material specifications. These specifications

have merit of course, because they establish a minimum level of quality

that the manufacturers of packaging materials must meet. However,

methods of material handling have changed, the transportation

environment is continually changing, and new and cost conscience

packaging methods and materials are continually being developed. Use of

these new methods and materials may be restricted until their adequacy

has been determined.

Current methods of testing involve lengthy periods of trail shipments

214
and evaluation. While field testing is eventually necessary for all con- tainers, it is not always the best way to begin evaluating containers.

Performance testing can enhance field test programs by assuring a higher

probability of successful tests.

The purpose of performance testing is to provide a rational basis for the

evaluation of packaging materials and methods, and to provide a means to

determine levels of packaging that are both adequate and economical.

Preshipment performance testing should enable the packaging engineer to save time and money and to reduce loss and damage. It will help reduce

excess costs of overpackaging, reduce costs of new package development,

and reduce total costs of trial shipments, while improving chances of success. Inasmuch as the transportation regulatory agencies recommend

and usually require preshipment testing to support the application for

test shipment permits, the results obtained from these performance test

procedures should improve the shippers' chances of obtaining the test

permit and the desired classification,

This proposed ASTM practice is based upon the concept that each mode of

transportation or portion of the distribution cycle has its unique set of

hazard elements that a shipping container must endure and survive,

regardless of the nature of its contents. The practice provides a uniform basis for evaluating, in a laboratory, the ability of shipping

containers (or shipping units) to withstand particular distribution en- vironments. This is accomplished by subjecting the containers to a test

plan consisting of a sequence of anticipated hazard elements encountered

in various distribution cycles. Each identified hazard element is

simulated by an established ASTM test method. The tests are conducted in

sequence on the same container or lot of containers making up the

shipping unit, which is the smallest complete unit that will be subjected

to the distribution environment. The recommended test levels are based

on the best available information on the shipping and handling

environment and current industry practice and experience.

Test levels are adjusted on the basis of probability of occurrence of the

hazard and the degree of assurance desired that the package and product

will not be damaged in shipment. Three recommended test levels are provided so that the user can determine the appropriate "assurance level"

for his product. Level I is a high level of test intensity. If the

shipping container passes this test level, it will have a low probability

of being damaged in shipment. Level III is the lowest level of test

intensity, but the container that passes this test would then have a higher probability of being damaged in shipment (thus a lower assurance

level of safe shipment). Level II is midway between the other two test

intensity levels and would be most cotmionly used.

Acceptance criteria for the condition of the package and the product at

the end of the test must be established prior to testing. The

organizations conducting the test must agree on the acceptance criteria.

215
but may choose any criteria suitable to their purpose. Usually, the

criteria that the product is damage-free and the package is intact would

be used, but other criteria for both package and product may sometimes be

desirable.

The shipping environment is categorized in 14 different distribution

cycles, each of which has its own sequence of hazard elements and

associated standard test methods. These cycles are based on air, truck,

rail and combinations of these means of transportation. It is considered

that the categorization of distribution cycles used is adequate but not

excessive. The format of the proposed standard is such that additional

distribution cycles and hazard elements can easily be added as new information is obtained or new modes of distribution developed. The

proposed standard is presently limited to domestic common carrier shipments, but export and other modes may be added in future revisions.

Seven hazard elements have been defined, including handling shocks,

three forms of vibration, vehicle impacts and compressive loading forces

experienced in stacking. Standard ASTM test methods are used to

determine the ability of the shipping unit to withstand these hazards.

For an example of how to use this performance test, consider a new industrial package unitized on pallets. The product is shipped by rail

directly to the end user. Handling occurs at the production point and

the warehouse of the user. We would like to determine if the package can survive the "complete distribution cycle".

Utilizing the ASTM performance test, choose a distribution cycle related

to rail shipment of unitized products and an assurance level

corresponding to the product value and amount of damage tolerated.

Several hazards are identified which are represented by ASTM test

procedures conducted in a series.

The first test is a mechanized handling test, consisting of a rotational

impact on each base edge of the pallet from a height of six inches. The

second test in sequence is a compression test, simulating vehicle

stacking. Containers with product are loaded in top-to-bottom

compression in a compression testing machine. The test load value is

determined by the superimposed load encountered in vehicular stacking,

multiplied by a factor to account for the response of the container

material to possible creep, moisture, various temperature environments,

and other derating factors. When the load value is reached, it is held

momentarily and then released .

The third test in sequence is a stacked vibration test. The unitized

pallet load is placed on the vibrator and a concentrated dead load is

placed on top to equal the weight of the upper tier of the load as stacked in the rail car. The shipping unit is then vibrated at 0.3 "G" over the frequency range from 3 to 100 hertz. Any stack resonances are

216
noted and a dwell time of ten minutes is imposed at each resonant

frequency. For test purposes in the AAR Container Laboratory, we sweep

between 2 and 25 hertz, dwelling at any stack resonance between 2 and 10

hertz.

Each package or unit is then subjected to horizontal shocks. These

shocks are designed to approximate the shock pulse of a standard draft

gear rail car at six (two impacts) and four (one impact) miles per hour

(these shocks are at the medium assurance level). This is one area where

a direct correlation between field testing and lab testing has not been

completely established.

The fourth test sequence is another handling test similar to the first

one, and the final test is a warehouse stacking test similar to the

vehicle stacking test, but with the imposed loads determined by expected

warehouse stacking heights.

At the conclusion of the testing, the products and packages are inspected

to determine if the acceptance criteria have been met and the report is

prepared.

It should be noted that these tests are nondestructive when the level of

packaging is adequate for the distributioin cycle used.

The AAR Container Laboratory began use of a modified version of this ASTM

performance test earlier this year. A recent test involved a sizable

claim against a railroad involving plastic bottles of vegetable oil. The

railroad asked the Container Laboratory to determine if the plastic

bottles were subject to vibration (abrasion) and impact damage. A performance test was designed to simulate warehousing as well as transportation. The test was much more severe than would normally be

found in rail transit. The end result of the test was that container

failure did not occur under laboratory conditions. The shipper and

carrier are now investigating other causes of the damage problem.

Another example of use of this test involved an evaluation of food

products. A rail carrier requested a performance test for a food

manufacturer who distributed solely by truck. One product in particular

was subject to damage during long distance transportation. A test series

was designed to approximate both rail and truck shipment. All test

packages performed well in both distribution cycles with one important

exception. The damage prone product had a higher incidence of failure

during vibration at frequencies normally associated with truck

transportation. At the lower rail frequencies damage occurred, but the

time frame was three times longer than at higher frequencies. As a result, rail test shipments are now underway.

These examples should show how performance test procedures can be used to

determine adequacy of products, packaging and optimum packaging levels.

217
Performance test procedures are not intended to replace existing

material specifications or established preshipment test procedures. It

is not to be used with hazardous materials, which must be packaged to meet

other rigorous rules that include specific performance requirements,

based on the properties and characteristics of the hazardous materials.

Use of performance testing can help reduce loss and damage to products by

increasing the efficiency of package development. The AAR Container

Laboratory is continuing studies of the best way to apply performance

testing and further improvement of existing test methods.

218
FIELD MEASUREMENT OF THE FATIGUE LOADING ENVIRONMENT

FOR RAILROAD FREIGHT EQUIPMENT

W. Sneed and A. M. Zarembski

Association of American Railroads

Chicago, Illinois 60616

ABSTRACT

Railroad freight equipment in North America operates in a broad range

of conditions for up to four decades. Consequently, the equipment must

be capable of surviving long term, fatigue inducing loading in addition

to short term structural loads.

In order to adequately design for fatigue life, a thorough knowledge of

the loading environment that revenue freight traffic experiences during

its lifetime is necessary. To obtain this information, a test program

was developed to measure loading input into the freight car structure

during over-the-road revenue service for extended periods of time.

The program used a stratified random sampling technique to develop

statistically valid representation of the loading and utilized a self

contained portable data aquisition system to record and store the

measured load levels. It is the purpose of this paper to describe both

the data sampling techniques developed to define representative load

environments, and the actual measurement system and hardware used to

obtain the specific load data.

219

*

SESSION V

DESIGNING FOR TRANSPORTATION OF HAZARDOUS

MATERIALS (NUCLEAR MATERIALS AND WASTES)

CHAIRMAN: ROLAND POPE

SANDIA NATIONAL LABORATORIES

TRUCK AND RAIL SHOCK AND VIBRATION ENVIRONMENTS DURING NORMAL TRANSPORT

G. H. Lamoreaux

Sandia National Laboratories

Albuquerque, New Mexico 87185

A. A. Trujillo

Sandia National Laboratories

Albuquerque, New Mexico 87185

C. F. Magnuson

Sandia National Laboratories

Albuquerque, New Mexico 87185

Abstract: The Sandia National Laboratories Transportation Technology

Center (SNL/TTC) provides technical management and support for programs

which span a broad range of technical problems related to the transport

of nuclear materials.

As part of this program, SNL has obtained data on the shock and vibration

experienced by large shipping casks during normal transport. These

data were initially generated under contract to the U. S. Nuclear Regulatory Commission (NRC) by:

1) Extracting, reviewing, and reducing the shock and vibration environment definitions on file in the DOE/DOD and DOE Transportation Data

Banks,

2) Determining the best estimates of the environments for 1 arge shipping

containers on trucks and railroad cars,

3) Defining and conducting tests to obtain any additional data required,

4) Conducting dynamic analyses of the shock environment experienced by

cargo during rail switching and coupling to identify the dependence

of the shock environment on heavy cargo weights and on shock attenuation couplers, and,

5) Using the results to refine the estimates of the shock load description.

As part of the follow-on activity at the TTC, sponsored by the U. S.

Department of Energy, two approaches for using the data to estimate

the shock and vibration environments were investigated. The first is

a shock spectra approach which assumes that there is a singl e-degree-

*This work sponsored by the U. S. Department of Energy under Contract

DE-AC04-76DP000789 and U. S. Nuclear Regulatory Commission under Contract

A-1 049-6.

223
of-freedom dynamic interaction between the cask, tie-downs, and vehicle

bed. The second, or direct measurement approach, assumes that the cask

is rigidly attached to the vehicle bed and consequently , for 1 ow frequency

excitations, no such interaction takes place. Based upon the results

of these activities, the need for additional data was identified and

tests were planned to obtain the required data. Details and results

of the overall program are presented.

Key Words: Cargo tie-down design guide; over-the-road/rail dynamic

measurements; rail car coupl ing tests; shock and vibration data; transportation environments for radioactive material shipping containers.

Introduction

The Sandia National Laboratories Transportation Technology Center (SNL/

TTC) provides technical management and support for programs which span

a broad range of technical problems related to the transport of nuclear

materials. One of these programs involves the gathering of shock and

vibration data for the normal transportation environments of large radioactive material shipping containers. These data will be used to formulate

criteria for the design of restraint, or tie-down systems for such

containers. Data acquisition has been underway at the SNL for several

years. The appl ication of the existing data to heavy cargo was originally

funded by the U.S. Nuclear Regulatory Commission (NRC) . Under the original

NRC agreement, SNL was to work on the following tasks:

1) Extract, review, and reduce the shock and vibration

environment definitions on file in the Department of

Energy/Department of Defense (DOE/DOD) and DOE

Transportation Data Banks,

2) Determine the best estimates of the environments

for large shipping containers on trucks and

railroad cars,

3) Define and conduct tests to obtain any additional

data required,

4) Conduct dynamic analyses of the shock environment

experienced by cargo during rail switching and

coupling to identify the dependence of the shock

environment on heavy cargo weights and on shock

attenuation couplers, and,

5) Use the results to refine the estimates of the

shock load description.

The TTC intends to continue the shock and vibration investigation by

building on the work completed under the NRC contract.

224
This paper will define the problem as currently perceived by the TTC,

review the NRC contract work , and final ly discuss proposed future work to

be completed.

Problem Definition

There are many problems, both technical and administrative, asso- ciated with tryinq to define tie-down loadings for nuclear material

transportation systems.

The administrative problems stem from tryi ng to conduct realistic

overthe-road type tests. Negotiations must be conducted with both the

shipper and the carrier so that necessary waivers are obtained and

laboratory personnel are allowed to participate in the shipment. Preparations for the tests described later in this report took from a few months to approximately 2-1/2 years, depending on the type of test

and number of agencies involved. However, once the tests were set up,

the cooperation of the carriers and their employees was excellent and

the measurements were made in a relatively short amount of time.

The technical difficul ties arise from the wide variety of hardware

configurations which must be considered. Each configuration has many

parameters which affect the loads seen by the cask restraints. Some

of the important parameters are listed below:

1. cask mass

2. tie-down stiffness

3. tie-down damping

4. vehicle mass

5. vehicle structure stiffness

6. vehicle suspension stiffness

7. vehicle suspension damping

8. speed

9. tire pressure (for trucks)

If only maximum and minimum values are considered for each of the nine

parameters, 51 2 separate configurations must be evaluated through testing

or analyses or both. Furthermore if an average value is considered in

addition to these extreme values, 19,683 evaluations are required. Clearly

the problem must be reduced to manageable proportions. This is done by

making worst case assumptions about some of the parameters. For instance, one might assume that the worst shock input will occur when the tires

are at maximum pressure and the vehicle is traveling at some maximum

speed. It is believed that these assumptions can be made for tie-down

and suspension damping, tire pressure, and speed. If this is indeed

the case, the number of evaluations can be reduced to 32 if only two

values per parameter are considered or 243 for three values.

225
However, this is still an appreciable problem since the evaluations

must be made in three directions (vertically , longitudinally, and laterally) and for at least two, and possibly more container shipping orientations. Although testing provides accurate measurements of loadings

for specific configurations, this alone is not feasible from a time

and cost standpoint because of the number of tests required. Testing

is also limited to existing, available systems and it is therefore

diff icul t, if not impossibl e, to envelop all possible parameter values.

On the other hand, a strictly analytical approach may be risky,

unless the results are correlated in some way to the real world. Consequently, a preferred approach is one which uses analyses to envelop

important parameter values and then confirms the analytical results with

test data. Such is the nature of the problem. The next section describes

work already completed in attempting to solve the problem. The TTC's

proposed approach to completing the solution is outlined in the final

section of this report.

Completed Work

The DOE/DOD data bank referred to earl ier (task 1), was established

to make existing shock and vibration data available to both DOD and DOE

designers. The transportation data which had been gathered over many

years (beginning in the early 1960s) were reviewed in 1975' to fulfill

the requests in tasks numbered 1 and 2. In using these data, it was recognized that they had been accumulated for purposes of defining the

shock and vibration environments during transport of relatively lightweightcargo. Truck data covered cargo weights from essentially no-load

to 14 tonne (15 tons). Over-the-road rail data were available for 14-tonne

(15-ton) cargo. Rail coupling data were available for cargo weighing

about 4.5 tonne (5 tons). Since spent fuel casks can be much heavier

than these weights, it was obvious that additional data needed to be

gathered to aid in properly defining the dynamic transportation environments. The needed data were those of shock and vibration during normal

rail and truck transport of heavy cargo and for rail coupling data when

heavy cargo is involved.

Over-the-Road Truck Tests

An opportunity to gather data during truck transport was presented

when SNL procured two spent fuel shipping casks weighing 20 tonne (22

tons) and 25 tonne (28 tons) for use in a series of vehicle-container

impact tests. Both casks were to be moved over conventional highways

from the DOE Nevada Test Site, which is northwest of Las Vegas, Nevada,

to Albuquerque, New Mexico for the impact tests.

226
Each cask was mounted on a dedicated trailer. The cask support

and tie-down structures were welded to structural members of the trailer.

The 20-tonne {22-ton) cask was carried on an 11 m (35-foot) tandem

axle trailer which was equipped with an air bag suspension system ( Figure

1) . The 25-tonne (28-ton) cask was carried on a 12-m (40-foot), 3-axle

trailer which was equipped with a spring suspension system (Figure

2) .

Both shipments were moved by similar tandem axle tractors which were equipped with "Velvet Ride" suspension systems.

Instrumentation on these trail ers consisted of accel erometers mounted at the base of the cask support structures. The accel erometers

were mounted to measure excitations in the longitudinal, transverse,

and vertical directions. Theleadsfrom the accel erometers were connected

to the data acquisition system which was mounted on the trailer.

Data gathering was accomplished by using a SNL developed data ac- quisition system. This system is self contained in that it can be

operated without any external power supply. The system has the capability

of recording 14 channel s of data. Itcan receive, condition, and record

signals from both piezoelectric (high frequency) and piezoresi stive

(low frequency) accel erometers. The conditioned signal is recorded on magnetic tape which is one-inch wide and is compatible with SNL'sdata

reduction equipment. At 19 cm/sec (7-1/2 in/sec) recording speed,

which provides data up to 2500 HZ, the system can record about 30

minutes of real time data. This 1 imitation makes data sampling necessary.

The data acquisition system can be started and stopped by either

switching at the instrument box, by hard wire connection, or by a radio control transmitter which permits taking data samples from a remote

location up to about 0.8 km (1/2 mile) away.

The data acquisition system contains a standard interange instrumentation group (TRIG) B time code generator from which a signal can

be placed on the data tape for use in identifying events during data

reduction.

The route over which the shipment was made was determined by the

commercial carrier through their normal routing procedures. Locations

where measurements were to be taken for these tests were determined by

making preliminary road surveys and by identifying the locations along

the highway to be sampled. The locations identified were bridges, cattle

guards, rough highways, as well as different types of highways.

During the shipment, data samples were gathered by remotely con- trolling the data acquisition system from a vehicle carrying Sandia

personnel. This vehicle followed the truck carrying the casks and

as the truck approached the predetermined location, the recorder was turned on remotely. After the event had been passed, the system was turned off.

227
Figure 1. 20 Tonne Truck Cask
For data reduction and definition purposes, the measurements were

defined as either shock or vibration. Vibration is considered a steadystate or continuous excitation while the vehicle is in motion. Vibration

data samples recorded were generally about one-minute long. Shock is

defined as a high-amplitude, short duration excitation. Shock events

which occur during over-the-road type measurements are short segments

of a data sample and therefore include any background vibration. Atypical

accel eration-time plot is shown in Figure 3. This data sample is for

the vertical axis at the rear of the 25-tonne (28-ton) cask shipment

when it crossed abridge at 89 km/hr (55 mph). These data were filtered

at 2,000 Hz low pass and digitized at 5,000 samples per second. Data

from these tests are summarized in references 2 and 3.

Rail Car Coupling Tests

Coupling rail road cars together to make a train is sometimes accom- plished through the use of a hill or hump. This hump consists of

a raised track over which the cars are passed and allowed to roll

free. The cars are then directed through a switching system, onto

the appropriate track. The coupling is completed when the car impacts

the portion of train al ready made up. This procedure is commonly called

humping. Based on 15,648 observations of humping, 99.8 percent of

the cars impacted other cars at or below 18 Km/hr (11 mph). Data were

available from tests at this velocity but for much lighter weight cargo

than was under consideration for spent fuel casks ; therefore, additional

data were needed.

Savannah River Laboratories planned to conduct rail coupl ing tests

to aid in defining tie-down requirements as part of developing a standard

for an American National Standards Institute (ANSI) subgroup. SNL was

asked to gather data during these tests. Two spent fuel casks were

used in these tests, one weighed 36 tonne (40 tons) and the other

weighed 64 tonne (70 tons).

The tests were conducted by running the test car up to the desired

speed with a locomotive, releasing the test car, and allowing the test car to impact into four ballast cars weighing about 307 tonne (338

tons) total. The ballast cars had all slack removed from the couplers

prior to impact and the brakes were set. Three test cars were used

in the tests. These cars were equipped with standard draft gear, a 38-cm (15-inch) hydraulic end-of-car device, and a sliding center sill.

The 36-tonne (40-ton) cask was attached to the rail car using

two methods. Longitudinal restraint was provided by steel stops which

had been welded to the rail car structure for both tie-down methods.

Vertical and transverse restraint was provided by bolts through the

skid and car structure in one case (Figure 4) and by cables in the

229
66,000 lb CASK SHIPMENT ON TANDUM AXLE TRUCK

- 3 AXLE TRAILER - SPRING SUSPENSION

230
Flqure 4. 36 Tonne Rail Car - Bolt Tleiowns

Figure 5. 36 Tonne Rail Cask - Cable Tiedowns

231
other case (Figure 5). The 64-tonne (70 ton) cask was attached to the

rail car using the same horizontal restraint as with the 40-ton cask.

Vertical and transverse restraint was provided by bolts (Figure 6).

Instrumentation in the coupl ing tests consisted of 21 accel erometers, one coupl er force transducer, one coupler displacement measuring device,

three tie-down force transducers, and two rigid stop transducers. The

signals from these 28 instruments were fed to 2 signal conditioning

packages, then to a telemetry transmitter, and finally to a SNL-supplied

receiving van located near the test site. At the receiving van, the

transmitted signals were received and put on magnetic data tapes.

Data reduction was accomplished at different laboratories which

participated in the tests. Typical force-time and displ acement-time

plots for the coupler are shown in Figure 7. A force-time measurement

obtained between one of the two horizontal stops and the skid is shown

in Figure 8. An acceleration-time plot measurement at thecar structure

near the coupler for the same test is shown in Figure 9. Table 1 shows the conditions and configurations of the 18 tests which were conducted.^

Over-the-Road Railroad Test

An opportunity to gather data during a normal over-the-road rail

shipment was presented when SNL was involved in modifying a spent fuel

shipping cask. The modifications were made in Denver, Colorado, and

the cask was to be shipped to Socorro, New Mexico. The weight of this

cargo was about 45 tonne (50 tons).

During this shipment the cask was mounted on a 21-m (68-foot) long

flat rail car which was equipped with a 38-cm (15-inch) end-of-car

coupl ing device. Longitudinal and transverse blocking was accomplished

by using hardwood blocks. Vertical tie-down was accomplished by two

cables (Figure 10).

Twelve accel erometers were mounted on the rail car structure to

gather data in the longitudinal, transverse, and vertical axes. Two

data channels were used for recording IRIG B time and for electrical

noise detection. Signals from the accel erometers were fed to the data

acquisition system which was mounted on the instrumented rail car. The data acquisition system was started and stopped remotely by Sandia

personnel who rode in a caboose immediately behind the test rail car. Preliminary road surveys were not conducted for this data gathering

exercise. The rail carrier was very cooperative throughout the test.

Locations for data samples were identified by providing detailed road

profil e maps and having experienced rail road personnel aboard the caboose

with the Sandia personnel.

232
Flqure 6. 64 Tonne Cask - Bolt T1e<1oi#ns

40T CASK ON P22. 8TD DRAFT GEAR . 10.7MPH 0 .200 .400

TME M SECONDS

Fiqure 7. Rail Couplinq Tests - Typical Force-Time and

Oispl acenent-Time Records

233
234
Table 1

Summary of Test Configurations and Impact Velocities

Test Test Cask Weight Impact Velocities

No. Car* Coupler tonne (Ton) km/h (mph)

1 A Standard 36 40 13.36 8.3

2 A Standard 36 40 14.65 9.1

3 A Standard 36 40 16.90 10.5

4 A Standard 36 40 17.22 10.7

5 A Standard JO 1 on 1 u . D gw u 36 40 4.44 2.76

7 B End-of-Car 36 40 9.06 5.63

8 B End-of-Car 36 40 14.73 9.15

9 B End-of-Car 36 40 14.73 9.15

10 A Standard 64 70 12.91 8.02

11 A Standard 64 70 - 17.98 11.17

12 B End-of-Car 36 40 18.02 11.2

13 B End-of-Car 36 40 17.86 11.1

14 B Standard 36 40 8.69 5.4

15 B Standard 36 40 10.46 6.5

16 B Standard 36 40 17.38 10.8

17 C Cushion 36 40 9.50 5.9

18 C Cushion 36 40 17.22 10.7

*A = SCL car; standard couplers

B = UCC car; mixed couplers

C

= SCL car; cushion underframe

Figure 10. 45 Tonne Rail Cask

235
The instrumented test rail car was placed at the rear of the trains

during the shipment. The only cars behind the test car were cabooses

-- one for test personnel and one for the train crew. The trains on which the shipment was made consisted of 43, 46, 53, and 55 cars. The data from this test are still being evaluated.

Proposed Future Work

Several methods of applying the gathered data to the tie-down

design problem are being investigated. These investigations indicate

that additional data are needed to formulate a general design criteria

for nuclear material shipping container tie-downs. The TTC therefore

intends to initiate a program which will provide enough data to formul ate

the necessary design criteria. The steps in this program, in general

terms, are listed below.

1. Establish important transportation system parameters.

2. Determine which of these parameters can be held constant

by making worst case assumptions.

3. Perform analyses which will use enveloping values for

those parameters which cannot be held constant.

4. Validate the analysis results through correlations with

experimental measurements, using existing data where

possible and gathering additional data if needed.

5. Establish correlations between analytical results and

system parameters which can be used to determine design

loads for the tie-downs.

These steps are not necessarily in chronological order. In fact,

it is expected that item five, for instance, will naturally evolveduring

efforts to complete the other four.

The ultimate goal of the outlined program is to develop design

criteria that can be applied easily and safely. The real question at

hand, then, is not whether the program will lead to design criteria,

but how easily applied and mistakeproof the criteria will be. In the

opinion of the authors, the TTC program will lead to the development

of criteria that can be readily appl ied, with a high level of confidence,

to the design of tie-downs for radioactive material shipping containers.

236
References

1. C. F. Magnuson and L. T. Wilson, "Shock and Vibration Environments

for Large Shipping Containers on Rail Cars and Trucks" , SAND76-0427,

Sandia National Laboratories, Albuquerque, New Mexico, July 1977.

2. C. F. Magnuson, "Shock and Vibration Environments for a Large Shipping

Container During Truck Transport (Part I)", SAND77-1110, Sandia

National Laboratories, Albuquerque, New Mexico, September 1977.

3. C. F. Magnuson, "Shock and Vibration Environments for a Large Shipping

Container During Truck Transport (Part ID", SAND78-0337, Sandia

National Laboratories, Albuquerque, New Mexico, May 1978.

4. C. F. Magnuson, "Shock Environments for Large Shipping Containers

During Rail Coupl ing Operations", SAND79-2168, Sandia National Laboratories, Albuquerque, NM, June 1980.

237
THE NATURE OF TRANSPORTATION ACCIDENTS

INVOLVING RADIOACTIVE MATERIAL PACKAGINGS*

E. L. Emerson and J. D. McClure

Sandia National Laboratories

Albuquerque, NM 87185

Abstract: This paper analyzes the transportation accidents and incidents which have occurred in the United States in the period 1971-1980

based upon the information in the Radioactive Material Transportation

Accident/Incident Data Base developed by the Transportation Technology

Center (TTC) at Sandia National Laboratories. Principal sources of

this information are the Hazardous Material Incident Reporting system

of the U. S. Department of Transportation and information from the

files of the U. S. Nuclear Regulatory Commission (NRC). Detailed

statistics are provided for transportation accidents, handling accidents, package types involved and material transported.

Key words: Accident; data base; failure; handling accidents; hazardous

materials; HMIR's; radioactive material ; radioactive material transportation; radioactive material transportation accidents; radioactive material transportation analysis; radioactive material transportation incidents; packaging; transportation; vehicle.

This paper analyzes the transportation accidents and incidents which

have occurred in the United States in the period 1971-1980 based upon

the information ni the Radioactive Material Transportation Accident/

Incident Data Base developed by the Transportation Technology Center

(TTC) at Sandia National Laboratories. The accident/incident data

base incorporates the files of the Hazardous Material Incident Report

(HMIR) system operated by the Material Transportation Bureau of

the US Department of Transportation (DOT) with additional information

obtained from the files of the US Nuclear Regulatory Commission (NRC).

A principal objective of this paper is to summarize US accident/incident experience for the past ten years, thus providing a concise

statement of the radioactive material (RAM) package environment for

the transport modes of truck, rail and air.

Operated for the US Department of Energy (DOE) by Sandia National Laboratories, the TTC acquires hazardous material incident reports from the

DOT on a continuing basis. This information, plus similar information

acquired from the NRC, provides a radioactive material accident/incident

*Work sponsored by the US Department of Energy under Contract DE-AC04-

76DP00789.

238
data base which consists of 750 data entries for the years 1971-1980.

For the same period, the HMIR system has 105,182 entries for all classes

of hazardous materials, including 585 radioactive material entries, or 0.56 percent of the total incidents reported to DOT. This information

represents US transportation experience for radioactive materials dating

from 1971 through 1980. The accident/incident data base is stored on TTC's on-line data base management system for rapid storage, retrieval,

editing and analysis.

The DOT regul atory requirements for reporting a hazardous material incident are specified by the Code of Federal Regulations (49 CFR, 171.15).

These regulations specify reporting after each incident that occurs

during the course of transportation (including loading, unloading and

temporary storage) in which as a direct result of moving hazardous material: (a) a fatality occurs; (b) a person receives injuries requiring

hospitalization; (c) estimated carrier or other property damage exceeds

$50,000; (d) in the case of radioactive material there is fire, breakage, spillage or suspected contamination; (e) fire, breakage or spillage

occurs involving etiol ogic agents; (f) a situation exists that, in the

carrier's judgement, should be reported, e.g., a continuing danger of

life exists at the scene of the incident.

The NRC '•p^ul atory requirements for reporting a radioactive materials

incident are specified by the Code of Federal Regulations. 10 CFR

20.402 concerns the theft or loss of radioactive materials and 10 CFR

20.403 concerns exposure to radiation and release of radioactive materials.

From this summary of the requirements for reporting a radioactive materials incident, one can conclude that the requirements for reporting

vary widely. The data entries in the accident/incident data base are those which generally meet the regulatory requirements for notification

of DOT and/or NRC of an occurrence. The main theme of this paper is

that a detailed examination of the reports in the data base reveals

that some of the events can be classified as transport accidents, some events involve handling accident conditions and others are simply incidents which meet the regulatory requirement for reporting an event.

Such a classification of events is shown in Table I and is necessary

to produce, for example, accurate accident rate estimates for risk

assessment studies. Table I represents an up-to-date representation

of US radioactive material transportation experience, which show that

only 13.5 percent of the incidents involve transportation accidents.

In the interpretive analysis of the basic DOT and NRC information, a distinction is made between an accident and a reported incident. Two

types of accidents are categorized, as shown in Table I. For the purposes of this analysis, a reported incident is classified as a transportation accident if there is a vehicular accident involving the ve- hicle transporting the radioactive material. Other incidents are classified as handling accidents if during the course of handling.

239
loading, etc., an accident occurs to the package, for example, a package is dropped or is punctured by a forklift.

TABLE I

US Radioactive Material Accident/Incident Experience

(1971-1980)

Transportation Accidents 101

Handling Accidents 125

Reported Incidents, Other 554

Total 750

The remaining classification, "Reported Incidents, Other," excludes the

two accident categories and comprises the balance of the incident re- ports in the data base. These may arise from: (1) actual or suspected

release of radiation of materials; (2) surface contamination on the

package or transport vehicle in excess of regulatory requirements (49

CFR 173.397).

The suspicion of release results from many causes. The most common are minor damage to the outer container, wet packages, liquid leaking from a closed trailer and erroneous meter readings. The wet package occurs often in the shipping of radiopharmaceuticals by air. The first suspicion

is that the inner container failed. Subsequent investigation usually

determines that the package was loaded aboard the aircraft during rain

or snowfall. The liquid leaking from a closed trailer occurs frequently

after a truck has been driven through rain and later, during dry highway

conditions, the liquid that accumulated inside the rear trailer doors

seeped out.

Removable (non-fixed) surface contamination incidents are often noted

during radiation surveys in loading and unloading operations. They are most likely to occur when the trailer is being returned to general

highway use after a sole use shipment. Such events generally involve

no package failure, no release of radioactive contents and the absence

of any accident conditions during transport.

The 101 transportation accidents listed in Table I were classified by

transportation mode as shown in Table II.

Table III summarizes some of the information that can be retrieved from

the accident/incident data base. For example, the 101 transportation

240
TABLE II

Radioactive Material Transportation Accidents by Mode

Transport Mode Number of Accidents Number of Packaging Failures

Strong & Tight* Type A

Air 7 3

Rail 7 1 Highway 86 60 ^ 4

Courier Service 1 TOT "IT r

*49 CFR 173.392

TABLE III

Transportation Accident Analysis Summary

RAM Packages

Involved in

Accidents

Package Description

Description of Events

Description

of Material

Rel eased

Packaging 53 Strong & Tight 9 Release 6 Urban •Uranium

Fail ures* 5 Type A Events concentrate

(with release) •Monazite

sand

•RAM NOS

•Radiopharmaceutical s

3 Non- •Uranium^'^'^

Urban concentrate

Packaging 8 Strong & Tight

Failures* 2 Type A

(no release)

Packagings in 761 Strong & Tight

Accident with 237 Type A

No Failures 48 Type B

TOTAL 1114 packages involved in 101 accidents

*The 68 packaging failures involved 58 packages which released radio

active material

.

241
accidents involved a total of 1114 radioactive material packages. Some

accidents had only a single package on board the transport vehicle.

Other accidents involved a single transport vehicle with a number of

packages on board. Table III traces an analysis of the radioactive

material packaging failures in the 101 accidents.

Multiple numbers of packages can be carried on a single vehicle and nine

separate and distinct release events involving these packages have been

defined. Six of the release events occurred in an urban area. Three

of the release events occurred in a non-urban area. For example, the

Springfield, Colorado, accident involved 29 packaging failures which

released approximately 5400 kg of uranium oxide; this was defined as a single release event. For the nine release events, the material re- leased was described as uranium ore, radioactive sand (low specific

activity), uranium concentrate radioactive material (RAM--not otherwise

specified) and radiopharmaceuticals. It is interesting to note that

an examination of the accident data reveals that 48 Type B accident

resistant packagings were included in the set of packagings which were subjected to vehicular accident conditions, but produced no packaging

failure and, consequently, no release of radioactive contents.

Radioactive materials being transported in the accidents noted in the

data base include the following:

No. Material

4 Spent fuel casks (2 w/spent fuel, 2 empty)

24 Low level waste (RAM LSA)

14 Radiopharmaceutical

s

22 Radiography or oil well logging sources

8 Uranium concentrate

1 Monazite sand

8 Uranium Hexa fluoride

1 Teletherapy source

19 RAM LSA or RAM NOS

Tables IV, V, VI and VII present a chronological summary of the data

base with respect to the number of reported events, transportation accidents, handling accidents, release of radioactive contents and accident

occurrences by transport mode. The following observations apply to

Table IV. The accident/incident data base receives most of its data

entries from the HMIR system of the DOT. The other principal data source is the NRC. The HMIR data originated in 1971 and the NRC data

originated in 1976. Any calculation of rate of occurrence of accidents

and incidents should be performed with caution since the overall accident/incident data base consists of elements with differing chronological origination dates and completeness of information.

242
TABLE IV

Accident/ Incident Data Base Chronological Summary

Annual No. HMIR* Other** Transportation Handling Annual No.***

Year Incidents Incidents Incidents Accidents Accidents Release

1 1971 12 12 N/A 5 0 7

1 1972 21 21 N/A 1 2 5

1 1973 24 24 N/A 0 11 7

1 1974 60 60 N/A 5 16 10

1 1975 44 44 N/A 5 23 8

I 1976 62 58 4 4 6 14

! 1977 113 97 16 10 15 17

1 1978 149 92 57 20 15 22

1 1979 171 120 51 30 24 23

1 1980 95 57 37 21 13 20

750 585 165 101 125 133

*Reported events received from HMIR system, DOT.

**Reported events received from NRC and other sources. Reported events where material or excessive radiation was released

(all categories)

TABLE V

RAM Transportation Accident Summary

Transportation

Rail

Transport Mode

Year Accident Total Hi ghway Air Other Releases

1971 5 1 4 0 0 11 Rel ease-1971-Hwy

1972 1 0 1 0 0

1973 0 0 0 0 0

1974 5 1 4 0 0

1975 5 0 5 0 0

1976 4 0 4 0 0

1977 10 1 9 0 0 11 Rel ease-1977-Hwy

1978 20 0 19 1 0 11 Release-1979-Air

1979 30 2 24 4 0 11 Release-1979-Rail

1980 21 2 16 2 1 12 Release-1979-Hwy

(Courier) 11 Re1ease-1980-Air

101 ~7 m T T 19 Release Events

243
TABLE VI

RAM Handling Accident Summary

Year

Handl IngI

Accident!

Total 1

I Transport Mode i Rail Highway Air Other 1 Releases I

1971

1 0 ! 0 0 0 0

1

1 0

1972 2 1 0 0 2 0 1 1, Ai r 1 1973 11 ! 0 2 9 0 1 2, Air 1 1974 16 1 0 1 15 0 1 2, Air I 1975 23 1 0 6 14 2, Freight Forwarder! 2, Hwy 1

1 1, Marine I 1

,

( Ai r 1

1 1 1,, Frt Frd I 1,, Marine I 1976 6 ! 0 2 4 0 1, Hwy 1 1 Q77 1 K i

1 D 1

1 4 9 1, Warehouse 1 3,, Hwy 1 1,, Rail 1 1,, Warehouse!

2s Ai r 1 1978 15 1 0 8 7 0 2, Hwy 1 1979 24 I 0 9 1 1. Courier Service I 2, Air 1 3, Hwy ! 1980 13 1 0 8 5 0 1,, Air 1 2, Hwy 1

125 1 1 40 79 5

The most representative view of accident and incident rates is to ex- press their occurrence as fractions (or percent) of total shipping volume. The most recent estimate of total shipping activity in the US was performed in 1975.^ Estimates of present shipping activity are presently being investigated. Until new estimates of shipping activity

are available, it is not possible to gain a current assessment of the

percentage of accidents and incidents based upon numbers of radioactive

material shipments.

To conclude, it is important to note that the accident/incident data

base described in this paper represents the accumulation and organization of existing data sources available in the United States. This

data acquisition is followed by interpretive analysis of the information, and this analysis and data is shared with several government

agencies such as the DOE, NRC, DOT, Environmental Protection Agency

(EPA), Federal Emergency Management Agency (FEMA) and the International

Atomic Energy Agency (IAEA), as well as other interested state and

local governments and public interest groups. One important fact that

has come from the preparation of this report is the importance of per244
forming a detailed study of the incident reports and any attached docu

mentation. It is recognized that after such an examination of radioactive material transportation incident data that all of the reported

events are not transport accidents, hence the stratification of the

accident/ incident data as shown in Table I. Such a classification as shown in Table I is necessary because the varying requirements for re- porting hazardous material incidents allow a broad spectrum of data

entries which must necessarily be subclassified (i.e., transport accidents, handling accidents and reported incidents).

TABLE VII

RAM Handling Accident Analysis

Package No. No. Transportation Material s Description Fail Release Mode (No. of Events) Involved

Strong and 9 8 Hi ghway 4 RAM Small Quant.

Tight Water 1 RAM NOS 1 Freight 1 Uranium Concentrate ! Forwarder RAM LSA

Warehouse 1 Rail 1

Type A 65 33 Ai r 10 Radiopharmaceutical s Highway 9 RAM LSA

RAM NOS

Radiography

Sources

Cause for Handling Accident Report

Dropped in Handling 46 ' Run Over by Vehicle 27

Fell in Transit 24

External Puncture 21 Misc. 7

The information presented represents the most complete analysis to date

of the transportation accident/incident data base for radioactive materials. The results of such an analysis can be used to provide information about the environmental impacts associated with the transportation

245
of radioactive materials. In addition, such an analysis can provide information which is useful in the formulation of the regulations governing the safe transportation of radioactive materials.

1. A. W. Grella, A Review of Five Years Accident Experience in the U.S.

A. Involving Nuclear Transportation , IAEA-SR-10/5, International

TTtomic Energy Agency, August 19/6.

2. J. D. McClure and E. L. Emerson, A Review of U.S. Accident/Incident

Experience Involving the Transportation of Radioactive Materia!

(RAM) 1971-1980 , 6th International Symposium Packaging and Transportation of Radioactive Materials (PATRAM '80) November 1980.

3. Review and Assessment of Package Requirements (Yellowcake) and

Emergency Response to Transportation Accidents , NUREG-0535, Final

Report, Office of Nuclear Material Safety and Safeguards, U.S.

Nuclear Regulatory Commission, July, 1980.

4. J. D. Col ton and R. E. Emerson, Study of the Mechanics of a Transportation Accident Involving Natural Uranium Concentrate , NUREG/

CR-0558, Final Report, Office of Nuclear Material Safety and Safeguards, U.S. Nuclear Regulatory Commission, January, 1979.

5. C. M. Romander and J. D. Col ton. Mechanics of a Highway Accident

at Wichita , Kansas , Involving Natural Uranium Concentrate, NUREG/

CR-0992, Final Report, Office of Nuclear Material Safety and Safeguards, U.S. Nuclear Regulatory Commission, August, 1979.

6. Transport of Radioactive Material in the U.S., A Detailed Sunwnary

of Survey of Radioactive Material Shipments in the United States , BNWL-1972, NUREG-0073, Office of Standards Development, U.S. Nucl ear Regulatory Commission, May 1976.

246
PERCEIVED SAFETY OF TRANSPORTING HAZARDOUS MATERIALS*

R. T. Reese

E. W. Shepherd

Sandia National Laboratories

Transportation Technology Center

Albuquerque, New Mexico 87185

INTRODUCTION

This paper addresses an apparent anomaly in the transportation

of hazardous materials which involves the issue that safety as em- bodied in rules and regulations to limit the public's risk to "acceptable"

levels is not the same as the perceived safety of the transport activity.

The basic assertion of this paper is that there are reasons for this

difference between the measured or defined degree of safety in transportation and the safety of this activity as perceived by the public.

Safety, the condition of being free form undergoing or causing hurt,

injury, or loss, appears to incorporate the probability of exposure

to a hazard or danger. While safety may be difficult to measure in

absolute terms, it is possible to make decisions on how free from

harm an event might be. This decision process is judgmental in nature,

usually different for each individual or group and is based on the

likelihood of exposure to a hazard or danger. Further, any con- sideration of safety usually involves some consideration of risk.

Risk assessment techniques can be used to determine the probability

that an unwanted event will occur and what detrimental consequences

will result if it does, but perceived safety appears not to rely on scientific analyses. Perceived safety, however, can have a greater

influence on decisions than do objective analyses of probabilities and

postulated consequences.

Despite a wealth of data and information on the risks of a variety of personal and industrial hazards faced daily, public attitude

remains uniformly indifferent or, at most, is exercised selectively

for short periods of time. This public indifference seemingly disappears when transportation of hazardous--particul arly radioactive--

materials are considered.

The scope of this paper is narrow and tries to describe the re- lationship that exists between many variables that appear to influence

the public view of safety in hazardous materials transportation with

particular emphasis on radioactive materials. The major problem in

*This work done for the U. S. Department of Energy under Contract

DE-AC04-76DP00789

247
analyzing this issue of perceived safety is the lack of an accepted

framework or methodology in which a meaningful discussion and assessment

of the issue can occur by the institutions in society and government.

This paper presents a framework represented by an equation of several

variables and thoroughly describes each term.

PROPOSED FRAMEWORK

This paper, written from a technologist's viewpoint, suggests that

such a framework can be constructed which will relate the variables

applicable to perceived safety of transporting hazardous materials.

This framework may have other application to activities considered

hazardous or presenting some risk but those are left to the reader.

Using this framework, the discrepancies that exist between public understanding and analytical measures of consequences and risks occurring

in the transport process can be better described.

The suggested framework relies primarily on information that is

currently available on transportation systems and processes. This

information is summarized in Appendix A. The framework organizes this

information into a relationship which, for convenience sake, appears

as an equation. However, since the variables describing public

perception are unlikely to be mathematically independent, a conditional

(Boolean) relationship is given in Equation (1) which indicate varying

degrees of unquantified dependence. Perception (P) is considered to

be conditional ( —-^) on the variables shown in Eq. (1). The variables themselves are considered to be conditional on each other or biconditional {- ).

F(t) (1)

p = Perception

TF = Technical feasibility

PP = Political palatability

SR = Social responsibility

UA = Util ity assessment

MI = Media interpretation

F(t) = Familiarity as a function of time

Equation (1) brings together the significant variables and organizes public perception into a relationship in which discussions and

assessments can occur. The purpose of this conditional equation is to

present a body of information in a concise form. While it may be

impossible to compel an individual or group to accept a statement on

248
the degree of safety of hazardous material transportation, it is important to try to have an individual or group notice a body of information

and take notice precisely.

Equation (1) does not have a rfgorous mathematical foundation. Considerable work is needed to determine if and how a mathematical model can be developed. In addition, the manner in which the variables are weighted and how the mathematical manipulations are accomplished need

to be determined. The intent is to present a framework to more com- pletely address this divisive safety issue. It is hoped that by using

this conditional equation, an improved understanding of perception and

eventually a method for the technologist to be able to comprehend the

public's perception of activities they consider hazardous. The relationship between public perception of an activity considered hazardous or how the public accepts the associated hazards (risks) is not

addressed in this paper. However, it is suggested that, at a minimum,

some relationship exists between public perception and acceptance.

The conditional relationship proposed in Eq. (1) could be a basis for

evaluating public perception and, in turn, public acceptance.

The remainder of the paper is a discussion of each term of Eq.

(1) and how available information is incorporated into the variables.

TECHNICAL FEASIBILITY

Technical feasibility as defined by Parsons (Ref. 19) is that

body of data, information, and options that indicate a capability

to do something in both an efficient and safe manner. Coupled with

this set of quantified data elements is the research supporting the

anticipated results from technology. However, implementation of the

results of technical efforts often run into opposition. Recipients

of technological advances require some form of supervision and control

of the scientific and engineering activities.

The need to transport nuclear materials requires that transportation be made technically feasible. The major question is how to

move the materials safely. Therefore, packagings and containers are developed, standards for their design and testing are formulated,

and shipping systems developed or adapted from transportation industry are used to move these materials. The feasibility assessment

is a thorough consideration of the adequacy of the analyses, designs,

tests, operations and if the unanticipated has been provided for.

This term of Eq. (1) is based on four major public and environmental

concerns: (1) the degree of protection offered by the packagings,

containers, and shipping systems, (2) the types of hazards posed by

releases of the materials or wastes in the presence of dispersal

mechanisms (or ignition sources), (3) the immediate and lingering

aspects of detrimental health effects and damage to the ecosphere

249
from exposure to hazardous materials, and (4) indications that human

errors have been reduced and carelessness avoided. The technical

feasibility term of Eq. (1) is a recognition of the requirement to

perform the transport process in a safe, efficient, and cost-effective manner.

POLITICAL PALATABILITY

The political palatability term of Eq. (1) encompasses all those

actions by elected or appointed governmental officials in considering

an activity whose impact may be hazardous. This assessment is based

primarily on external considerations usually reflected in preferences

which often result from a public consensus regarding some action or proposal. Decisions in the political arena are often made with some sense of real or implied urgency in which incomplete scientific

evidence is available. Because hazardous materials transportation

affects virtually every community within the country and is increasing

in quantity and frequency, many citizens are concerned with its impact

on their locality. Such citizen concern directly impacts the politcal

pal atibil ity . For example, strident public demands that radioactive

materials not be shipped in or through their communities directly

affects political pal atibil ity.

The political process mandates that the elected official tries

to adopt a position reflecting his concern for public health and safety

while securing a favorable appraisal of his position by the electorate.

The politician will seldom take a position that would be considered

as forcing some hazardous activity on his constituents without some compensating benefit.

Therefore, transportation of hazardous materials exhibiting

selected characteristics (corrosive, explosive, flammable, oxygen

denying, radioactive, or toxic) and which do not portray a politically

palatable benefit to a community that is commensurate with the hazard

presented will affect the perception of its safety.

SOCIAL RESPONSIBILITY

Social responsibility encompasses the concern that current

actions and decisions will meet the tests of time. This third term

of Eq. (1) reflects the obligation to protect current and future generations from unwanted consequences from hazards produced today. The

public view of how responsibly these concerns are being met will influence the view of safety. These concerns are based on two assumptions:

(1) that consistent historical patterns of accident data have emerged

in terms of consequences to the public and (2) that established societal

institutions are sufficiently enduring that they can be used for predictive purposes. Therefore, social responsibility addresses the accuracy

250
of these two assumptions (1) that history is a predictor of future

problems and (2) institutions will continue to protect society.

Many devices and checks and balances currently exist to insure

that the concern for social responsibility is satisfied. Among them

are: (1) federal, state and local laws, (2) regulations at the same levels of goverment, (3) enforcement agencies, and (4) self-imposed

standards and checks developed by manufacturers, users, transporters,

and disposers of hazardous materials and wastes.

The fundamental question before society is the degree of protection

that can and should be offered current and future generations. What

appears to be desired is a continued situation in which the fruits

of technological advancements can be used and enjoyed balanced with

assurances that mankind, the ecosphere, and the genetic inheritance

can be maintained in a status quo or improved for each succeeding

generation.

UTILITY ASSESSMENT

This fourth term of Eq. (1) as used here is the recognition that

a planned action satisfies or aids some group. For example, the public

knows it has become necessary to organize, store, and dispose of hazardous wastes. The manner in which the processes associated with these

activities Is performed, who is affected, and who will be rewarded

are the elements to be considered.

The basic need to transport hazardous materials from manufacturers to users and the waste products to disposal sites is a premise

of this paper. The public has a limited, but sufficiently valid,

understanding that these activities causing this need has or could

provide benefits to them.

However, the utility assessment of transportation is questioned

when one or more of the following occur: (1) an incident or accident

(2) a new or different material is transported through a community,

(3) studies, analyses, or environmental impact statements are released which give data defining worst case conditions.

The major problem in evaluating the utility of a hazardous activity is separating the issues or possible effects involved. No one suggests that society should accept a potentially hazardous situation

just because their economic life depends on it. However, society

should at least attach a utility value to the operation that is meaningful and in their interest.

251
MEDIA INTERPRETATION

The purpose of news gathering and dissemination services is to

analyze and report the news while obtaining and keeping readers and

listeners. The media play an important part in defining that which

is newsworthy. The interpretation of incidents, accidents, or activities associated with transportation of hazardous materials is based

on what the media has determined will be of interest to its users.

The more that a particular event can appeal to basic human concerns

(i.e., fear), the more likely the event will be publicized.

Another aspect of media interpreation is the interaction with

technology developments. The more complex a technology is and the

more terms and jargon required to explain that technology to the

public, the more likely it will be scrutinized by the media. This

type of technology presents the opportunity for the media to present

spurious arguments that are not easily refuted and understood by the

public.

Transportation of hazardous materials satisfies these two

requirements for being newsworthy because (1) the term hazardous

means something to be afraid of and (2) hazardous materials are often associated with complicated technologies.

The media interprets the causes and effects of an event. There

is a distinct difference in the media treatment of a single "big"

event and a series of similar individual events scattered over time.

Clearly, the single big event is more newsworthy. Because accidents

or incidents involving hazardous materials occur infrequently, these

events are usually treated as major, causing fear, and represent

something more complicated than routine accidents.

FAMILIARITY AS A FUNCTION OF TIME

DuPont (Ref. 9) indicated that one important factor in public

evaluation of hazardous activities is whether something is familiar

or unfamilar. Those dangers which occur commonly such as travel by

automobile representing a risk of one in four of a serious personal

injury accident over a lifetime are not considered equivalent to risks

resulting from a much less frequent but unfamiliar event. Dangers from

commonly accepted activities are treated on a "what is" basis and

usually disregarded in decision-making by the public. However, hazards

from unfamiliar activities are discussed on a what if" basis and are incorporated into the same set of decisions.

If two activities exhibit equivalent detrimental consequences to

public health and safety and they were introduced concurrently, then

these two activities will probably be judged as an equal hazard by

the public. However, if one of these activities was introduced at

252
some prior date (1. e., 30 years ago), then the newer activity would v be undergo significantly greater public scrutiny. As the public

becomes accustomed to hazardous activities, they have characteristically become less concerned about them. The more often a group is

exposed to a hazardous activity the more familiar they will become

with it and exhibit fewer concerns. Perception can be changed only

be repeated exposure to a feared situation.

CONCLUSIONS

A framework for relating the variables involved in the public

perception of hazardous materials transportation was presented. The

framework consisted of a conditional mathematical equation in which

perceived safety was described by six basic terms (technical feasibility, political palatibility, social responsibility, utility assessment, media interpretation, and familiarity as a function of time).

The resulting framework provides the technologist with an initial

formulation to better understand public perception.

253
APPENDIX A

AVAILABLE INFORMATION

Shipment Information

There is a continuing need to know the quantities and types of

hazardous materials, packagings and containers and shipping systems

which move routinely in commerce. This information provides the backbone for risk assessment. Currently the only nationwide data available for radioactive materials is contained in the 1976 Battel le

Pacific Northwest Laboratory study. The Battel le study is currently

being updated to establish a data base that can be used to generate

quantitative descriptions of the paramters of the transport of radioactive materials. There have also been a number of studies performed

within particular states.

Less complete shipment information is available for other categories of hazardous materials. Two sources are referenced (23, 24).

Among the problems in obtaining more accurate information are the

following: (1) the large number of shipments (estimated at more

than 200 million) per year, (2) the proprietary nature of many shipments, and (3) the costs of obtaining such information.

Accident/ Incident Data

The definition of accident and incident must be explained because

of the legal requirements for reporting occurrences. The U. S. Deparment of Transportation (DOT) requirements for reporting a hazardous

material incident are specified in the Code of Federal Regulations

(49 CFR, Para. 171.15). These regulations specify that an incident

must be reported if (1) a fatality occurs, (2) an injured person

requires hospitalization, (3) estimated damage to the carrier or property exceeds $50,000, (4) continued danger of life exists at the

scene, (5) fire, breakage or spillage occurs involving etiological

agents, and (6) for radioactive shipments suspected contamination.

The data is gathered and organized by DOT into the Hazardous Materials

Incident Report (HMIR) system. As a subset of this data base, the

Transportation Technology Center (TTC) of Sandia has developed the

Radioactive Materials Incident Report (RMIR) system.

It must be emphasized that all incidents are not necessarily

accidents involving vehilce damage. The data from 1971-1980 for

radioactive material shows that about 13 percent of all reported incidents involved vehicular accidents. The 85 reported accidents Involved

711 packages or containers. In the same time period, there were 11

accidents involving explosions on interstate highways throughout

254
the country. The data give a brief summary of the accidents

in which hazardous materials are involved.

Role of Regulations

Through the Nuclear Regulatory Commission (NRC) and the Department of Transportation (DOT), the federal government of the United

States regulates such aspects of hazardous materials transportation

as packaging, vehicle safety, and placarding, and for radioactive

materials, physical security. Within the past decade, state and

local governments have also become involved in the regulation of

hazardous materials transportation. This state and local involvement gives rise to important policy questions: (1) To what extent

should the federal government regulate the transportation of hazardous materials throughout the country? and (2) To what extent is

state and local regulation permissible under federal law?

Central to the above two questions is an understanding of the

philosophy of regulations. Historically, control of safety related

activities received less emphasis than the interests of the shippers,

carriers, and suppliers. This emphasis shifted in 1967 with the

creation of the Department of Transportation. This shift resulted

in a government agency as the primary mover of regulations governing hazardous materials transportation.

The technical questions in the regulatory area are primarily

concerned with (1) determining if existing regulations provide a known level of safety or should they be changed and (2) if the

regulations are changed will the level of safety be affected (improved). A side issue not necessarily of lesser importance is that

of evaluation of cost-benefit aspects of regulatory policy.

There is a large body of information available on regulations.

Environmental impact statements contain summaries and rationales

for regulations. These regulations provide for normal operations

as well as standards for design and development of packages and

virtually all facets of the transportation system.

Liability and Insurance Coverages

As the number of shipments of hazardous materials has increased,

more people have become concerned about public liability and compensation issues. Radioactive materials shipments have received most

of the attention. One of the most misunderstood aspects of the

regulatory structure that applies to transport of hazardous materials

is the coverge for public liability.

255
In the case of radioactive materials, the regulatory structure

provides for very comprehensive system under the omnibus provisions of

insurance and indemnity coverage for public liability. The insurance

industry and the federal government have recognized that, even with

stringent standards for packaging and operation of transportation

systems, the possiblility of a transportation accident resulting in some measure of damage to persons or the environment cannot be eliminated. Therefore, the federal government and the insurance industry

provide coverage through the Price-Anderson Act and the federal tort

system.

In addition to these coverages for radioactive materials, other

systems are used for public liability for hazardous materials. The

Superfund (the "Comprehensive Oil and Hazardous Substances Pollution

Liability and Compensation Act") provide for large coverages.

Recent regulations have also required carriers to have their own liability coverages to protect the public and the environment.

Packages and Shipping Systems

The design standards and requirements for packagings and con- tainers for shipments of hazardous materials are the responsibility

of more than one federal agency. For shipments of all hazardous

materials except radioactive, DOT has defined the requirements

and certifies the packagings and containers. DOT determines that

criteria which define adherence to accepted and proven engineering

practices are followed. The U. S. Nuclear Regulatory Commission

(NRC) has established the requirements for packagings for radioactive materials. These requirements are based on performance

characteristics for normal transport (leaktightness) and postaccident conditions including impact, puncture, fire, and submersion.

Emergency Preparedness

Federal, state, and local agencies have responsibilities for

planning, obtaining equipment, training, and providing assistance

and direction in the event of emergencies involving hazardous

materials. In addition, industry has organized its own system to

aid those affected by spills or releases of hazardous materials.

The non-existence of emergency preparedness programs has been

cited as a reason to restrict the flow of hazardous materials in commerce. However, public concern has applied pressure to governmental agencies and has resulted in more resources applied to the

the concerns for protection from the effects of these materials.

In addition, the prompt actions by industry to respond to accidents

and the development of companies who specialized in cleaning up

256
spills of materials have also addressed these concerns. The result

is an improved perception that the existing emergency response

systems would adequately respond to accidents involving hazardous

materials and control the associated detrimental consequences.

Information Requirements

There is a continuing awareness of public officials and the public of the key role transportation plays in the utilization of hazardous materials. This awareness is reflected in issues involving ra- dioactive materials transportation including safety, the role of the

federal government, and current and evolving policy and policy trends

for areas not now covered. These issues and questions generate the

need for factual information and analyses of transport policies.

In addition, policymakers, program planners, and corporate decisionmakers need accurate and timely data on which to base their program

planning. The requirement to provide accurate and objective information to such a diverse group is a large task for transporters of

hazardous materials. This requirement is being met by a variety of

informational tools, techniques and media forms.

Information on many aspects of the transportation of hazardous

materials exist in files and libraries and more data are being added

on a continuing basis. A central repository and standard query

system do not exist. The problem with this aspect of what is known

about hazardous materials transportation is an evaluation of what

is "good" or "bad" or that which is relevant, useful, and objective

and that which is not.

257
REFERENCES

1 . An Appraisal of the Problem of the Handling, Transportation, and Disposal of Toxic and Other Hazardous Materials , Booz,

Allen, and Hamil iton, 1970.

2. S. Barnett, An Anthropological Analysis of the Cultural Dimensions of Technological Risk Assessment , The Planning Economics

Group, Boston, April 1981.

3. Characteristics of Hazardous Cargo Shipments on Virginia

Highways , 1975.

4. J. C. Chicken, Hazard Control Policy in Britain, Pergamon Press,

Oxford, England, 1975.

5. R. K. Clarke, et.al.. Severities of Transportation Accidents , SLA-74-0001, Sandia National Laboratories, Albuquerque, NM,

July 1976.

6. E. Crouch and R. Wilson, "Regulation of Carcinogens," Risk

Analysis , Vol. 1, No. 1, March 1981, pp. 47-66.

7. K. Duchon, "Technological Backlash in an Age of Public Awareness," Civil Engineering , January 1980, pp. 107-108.

8. R. L. Dupont, "The Nuclear Power Phobia", Business Week , September 7, 1981, pp. 14-16.

9. C. S. Fore, Transportation of Radioactive Materials: Legislative and Regulatory Information System, Proceedings 6th Inte r- national Symposium on Packaging and Transportation of Radioactive

Materials (PATRAM '80), Berlin (West), Federal Republic of Germany, November 10-14, 1980, pp. 1067-1071.

10. W. F. Hartman, C. Davidson, and J. T. Foley, Statistical Description of Heavy ^^^^ck Accidents on Representative Segments of Interstate Highway , SAND76-0409, Sandia National Laboratories, A1buquerque, NM, July 1977.

n. R. E. Holmes and L. Cave, Nuclear and Non-Nuclear Risk--An

Exercise in Comparabil ity , Pollution Prevention Consultants,

Ltd., for the European Atomic Energy Community of the Commission

of the European Communities, EVR 6417 en, 1980.

12. I. Hoos, Risk Assessment in Social Perspective , Proceedings of

the Fifteenth Annual Meeting of the National Council on Radiation

Protection and Measurement, National Academy of Sciences, March

14-15, 1979, pp. 57-84.

258
13. N. Howard and S. Antilla, "What Price Safety? The Zero Risk

Debate," Dun's Review, September 1978, pp. 48-57

14. R. G. Kasper, "Perceptions of Risk and Their Effects on Decision

Making," Proceedings Societal Risk Assessment— How Safe is Safe

Enough ?, General Motors Research Laboratories, Plenum Press,

October 8-9, 1979, pp. 71-84.

15. T. R. Lee, "Perception of Risk," Proceedings from the Assessment

and Perception of Risk , The Royal Society, London, November 1980,

pp. 5-16

16. E. Magnuson, P. Stoller, and J. M. Nash, "The Poisoning of

America," Time, Vol. 116, No. 12, September 22, 1980, pp. 58-69.

17. M. N. Maxey, Radiation Health Protection and Risk Assessment:

Bioethical Considerations , Proceedings of the Fifteenth Annual

Meeting of the National Council on Radiation Protection and

Measurement, National Academy of Sciences, March 14-15, 1979,

pp. 18-34.

18. J. D. McClure and E. L. Emerson, A Review of the US Accident/

Incident Experience Involving Transportation of Radioactive

Materials (RAM) 1971-1980 , Proceedings 6th International Symposium on Packaging and Transportation of Radioactive Materials

(PATRAM '80), Berlin (West), Federal Republic of Germany,

November 10-14, 1980, pp. 811-817,

19. E. M. Parsons, Jr., "Decommissioning and Nuclear Waste Disposal:

The Buck Stops Where?", American Association for the Advancement

of Science, Annual Meeting, Toronto, Canada, January 3-8, 1981.

20. R. T. Reese and R. E. Luna, Institutional Issues Affecting

Transportation of Nuclear Materials , Proceedings 6th International Symposium on Packaging and Transportation of Radioactive Materials, Berlin (West), Federal Republic of Germany,

November 10-14, 1980, pp. 309-315.

21. S. L. Salem, K. A. Solomon, and M. S. Yesley, Issues and Problems in Inferring a Level of Acceptable Risk , Rand Corp.,

R-2561-D0E, August 1980.

22. D. F. Salisbury, "Christian Science Monitor Editorial Policy on Nuclear Power," Atomic Industrial Forum, Info 81, Phoenix, AZ.,

February 25, 1981":

259
23. P. N. Slovic, Images of Disaster: Perception and Acceptance of

Risks from Nuclear Power, Proceedings of the Fifteenth Annual

Meeting of the National Council on Radiation Protection and

Measurement, National Academy of Sciences, March 14-15, 1979,

pp. 34-56o

24. C. Starr, "Risk Benefit Analysis and Full Disclosure," American

Association for Advancement of Science , Washington, D. C,

February 13, 1978.

25. C. Starr, "Risk and Risk Acceptance by Society," Current Issues

in Energy , Pergamon Press, New York, pp. 13-30,

26. C. Starr and C. Whipple, "Risks of Risk Decisions," Science, Vol. 208, June 6, 1980, pp 114f.

27. The Ten Most Critical Issues in Hazardous Materials Transportation , Transportation Research Circular, Transportation

Research Board, National Academy of Sciences, No. 219, July

1980.

28. Traffic Accident Analysis , Transportation Research Board,

National Academy of Sciences, Washington, D.C., 1974.

29. Transport of Radioactive Material in the U. S., A Detailed Summary of Survey of Radioactive Material Shipments in the United

States, 5NWL-1972, NUREG-0073, US NRC, May 1976.

30<. Transportation of Radioactive Materials by Air and Other Modes , US Nuclear Regulatory Commission, NUREG-0170, Vols. 1 and 2,

December 1977.

260
ANALYSIS, SCALE MODELING, AND FULL-SCALE TESTING

OF SHIPPING CONTAINERS FOR RADIOACTIVE MATERIALS

H. Richard Yoshimura

Sand i a National Laboratories

Albuquerque, New Mexico 87185

M. Huerta

Southwest Engineering Associates

El Paso, Texas 79987

INTRODUCTION

Abstract: This paper will discuss techniques for predicting the structural response under accident conditions of shipping containers designed for the transportation of radioactive materials. The techniques include numerical analysis methods as well as physical scale

modeling. These methods will be discussed with some examples, and com- parisons will be made between analysis results and those of full-scale

tests conducted subsequent to the analyses.

Key words: Spent fuel, radioactive materials transportation, spent

fuel cask, impact tests, physical seal e model ing, computer analysis,

lumped parameter analysis, finite element anlaysis and full scale testing.

The class of containers that these techniques have been principally

applied to are heavy (23,000 - 68,000 kg) lead shielded casks used for

the shipment of spent fuel rods. These techniques, however, are now being applied to a different type of container designed for low level

waste materials. This paper will focus on work related to spent fuel

casks.

Regulatory requirements for the containers include a specific series

of tests that a container must pass prior to being issued a license.

These tests include among others severe drop and puncture tests as

well as fire testing. The regulations require that it be shown either

by analysis or test that a particular container design can survive the

prescribed sequence of tests without loss of contents. The techniques

described in this paper can be utilized for this purpose. In addition

to being utilized for regulatory requirements, these methods over the

past few years have been utilized to analyze what will be termed "extra

regulatory" tests. These are tests which have been designed to be more

easily related to what could conceivably occur in the transportation

environment, but having an extremely remote probability of occurrence

[1]. An example of such an event is the broadside impact of a locomotive, traveling at high velocity, against a shipping container. This

paper will briefly review work which has been done in the area of

applying numerical analysis and scale modeling techniques to analyze

261
shipping containers subjected to this type of environment. Results of

these analyses will be described and related to actual full-scale test

results.

Reference 2 lists three accident scenarios for which the complete cycle

of mathematical analysis, physical scale model ing, and full-scale testing have been completed. These accident scenarios include: (1) a head-on impact of a tractor-trailer system, carrying a spent fuel shipping cask, into an extremely rigid reinforced concrete target at a velocity of 129 km/hr (80 mph), (2) a railroad crossing accident sce- nario where a spent-fuel cask is impacted by a locomotive traveling at

129 km/hr (80 mph), and (3) a head-on impact of a special railroad car carrying a spent fuel cask into the same target as test 1 above and at

the same velocity.

The results of these tests are discussed in detail in references 3, 4,

and 5. These results indicated that the techniques described in the

paper are valid for analyzing these types of impact environments. In this paper results from the first two test scenarios (grade crossing

and head-on impact), which were the only ones where the basic structure

of the cask underwent any amount of permanent deformation, will be

used as illustrations.

NUMERICAL METHODS

Numerical methods used to analyze the dynamic impact response of shipping casks include lumped parameter modeling and dynamic finite element

modeling. Both methods are dynamic techniques which discretize the

structure into elements. The lumped parameter technique uses a much

coarser discretization and is generally a one-dimensional model. It

is based on being able to estimate the force-displacement characteristics for the structure and solving the dynamic equations of motion

for the resultant spring-mass system, which can have linear and non- linear springs (couplings). This method has been used to model the

vehicular system and the cask in order to predict the approximate

velocity at which the cask would impact a hard surface after crushing

the vehicle structure. It can also be used to approximate the forces

acting on the cask during the impact. Figure 1 is an example of

such a model. Here the discretized structure is given an initial velocity in the direction of the target and the response of the system in

terms of displacements, velocities, and accelerations is obtained.

The model shown in Figure 1 was used in conjunction with the SHOCK

[6] computer program which solves the equations of motion. This program has capabilities for linear and nonlinear couplings with hysteresis effects, which are essential in this type of modeling.

Lumped parameter models have also been used to analyze only the container. In this case the container is discretized into a number of

elements for the impact analysis. In reference 7 it was found that a model containing about twelve elements gave good results for stress

values at different points in the cask. This work was limited to endon impacts but analysis for a lateral impact can also be accomplished

262
using lumped parameter techniques.

Finite element analysis techniques can be used to analyze container

response in much more detail. This technique can be used as a second

step in the analysis process. For example, the model of Figure 1 indicated the velocity at which the cask might be expected to impact

the rigid target. This impact velocity can then be used as input to a finite element model in order to obtain a more refined analysis.

Figure 2 illustrates such a model formulated as the second step in the

analysis. This model was used in conjunction with the HONDO [8] finite

element program and represents an axi symmetric impact condition. The

HONDO program has the capability of providing an impact boundary con- dition which simulates a very rigid target by applying restoring forces

to prevent node penetration across the target surface. This model

included nonlinear material properties and sliding interfaces between

the lead and stainless steel shells. As with the lumped parameter

model, the structure was given an initial velocity into the target.

The plot of Figure 2 illustrates the deformed condition that was calculated for the impact-end of the cask assuming an unyielding target.

The finite element model described above was axi symmetrical and as such it was a 2-dimensional model. Two-dimensional finite element

models of this type are very feasible and the computer run times are quite reasonable. Some problems which are basically 3-dimensional in

nature can sometimes be simplified into a 2-dimensional configuration

and still provide some very good indications of the response. An

example of this type of simplification is the analysis of a side

impact between a locomotive and a shipping cask. Figure 3 illustrates

the simplified model (undeformed finite element mesh) and a calculated

deformed shape for an instant of time that is 15 milliseconds after

the locomotive made contact with the cask. This model also utilized

the HONDO computer program and its sliding interface features. A num- ber of conservative simplifying assumptions were made in the development of this model. The results provided much insight as to the res- ponse of the system and indicated that the cask would not be breached

by such an impact.

Three-dimensional modeling of these types of impact problems where

large deformations are encountered requires very large amounts of com- puter time and is only feasible for simple problems. However, as the

state of the art progresses, it is expected that 3-dimensional analyses

will become practical. At the present time, they are very difficult

to accomplish. When a complete 3-dimensional analysis is desired,

scale modeling becomes a more practical analysis technique.

PHYSICAL SCALE MODELING

Scale modeling has proven to be a very practical method for modeling

complicated and severe impact problems [3,4,5,9,10]. The theoretical

basis for physical scale modeling originates from dimensional analysis

studies which indicate that if material properties are the same in the

model and the prototype, then the deformations will be similar given

263
that the impact velocities are the same. Two restrictions which are placed on this technique are that the material strain-rate effects and

gravity effects should be negligible. The first restriction is seldom

a problem. The second one is not a concern when one is analyzing high

velocity impacts where the structures are subjected to decelerations

which are much higher than gravity.

Theoretically the gravity field in a subscale test should be greater

than the earth's by the scale factor (The scale factor is the inverse

of the scale. For example, in a quarter-scale test the scale factor

is 4). Since the gravity field cannot be conveniently scaled, gravity

effects must be assumed to be negligible. Experience has shown that

this is a valid assumption in most impact problems where decelerations

having high g numbers are generally encountered. One item which should

be noted, however, is that the rebound phase of the impact will not

scale correctly; subscale models exhibit much higher rebounds. This

phase of the impact however is not of concern as secondary impacts are generally much less severe and the significant container damage, if

any occurs, will happen during the primary impact.

The basic relationships which exist between the model and the prototype

parameters are listed below. These are valid for impact velocities

which are equal between model and prototype. Here the subscript m denotes the model, p the prototype, and the letter n denotes the

scale factor. The basic relationships are

Defl ection = Yp/n

Stress or Pressure

Force = Fp/n2

Energy ^m = Ep/n3

Mass \=^ Mp/n3

Time

"^m = Tp/n

Accel eration = n(Ap)

In particular it can be seen that deformations (deflection) in the

model and prototype are similar. From the time relation, it can be

seen that events in the model occur faster by the scale factor. Thus

accelerations in the model are higher by the scale factor.

Previous work [9,10] using scale models involved experimental work

using exact replica models for verification of the analysis. The model

and the prototype were constructed of similar materials and were geometrically scaled. In both cases, agreement between the model and the

prototype was found to be excellent.

264
The structures for the tests described were considerably more complicated and the additional assumption that a somewhat simplified model

will give valid results was made. Substitution of an approximate (simplified) model, as opposed to an exact geometrical model was often

done for practical considerations and was necessary in order to reduce

costs. Such a model is usually termed an "adequate" model (11). The

models described in this paper were designed according to this concept,

although the shipping cask models were very detailed.

In the scale modeling work performed at Sandia National Laboratories,

one-eighth and quarter-scale models have been successfully utilized

to model shipping casks and complete shipping systems, including

vehicles.

Figure 4 illustrates photographs of eighth scale models used to analyze

the tractor- trail er impact and the grade crossing test. These tests

were conducted at a sled track facility where the models were accelerated up to the impact velocities by small rocket motors.

The scale model tractor-trail er test resulted in the cask impacting

the target in very close to an end-on condition. This impact resulted

in slight "mushrooming" of the head end of the cask but did not threaten

containment. The scale model grade crossing impact test resulted in

two small deformations on the side of the cask where the longitudinal

locomotive underframe members impacted the cask. The containment of

this cask was also not threatened. These results will be discussed

further bel ow.

FULL-SCALE TESTS

Full-scale tests were conducted to confirm the results of the analyses

techniques and to obtain data on the response of full-scale systems.

Large rocket motors attached to a pusher sled were used to propel the

vehicles up to speed on a test track which guided the equipment to the

impact point. Used surplus equipment was used for all the tests.

Data were obtained by use of instrumentation and high speed photography.

Figure 5 is a photograph of the full-scale tractor- trail er system that

was impacted into a rigid barrier at 135 km/hr (84 mph). At this

velocity the vehicular system was completely destroyed. The shipping

cask plowed through the cab and completely crushed the impact limiter.

The cask then impacted the target in close to an end-on condition.

The complete impact event took approximately 0.2 second with the cask

(system) rebounding slightly from the target as is seen in Figure 6.

The response was extremely close to what the model had predicted and

the cask was only slightly deformed on the impact-end. At the worst

point there was approximately a 3% diametral expansion.

Figure 7 illustrates the full-scale locomotive and tractor-trailer rig

used for the grade crossing test. In this test the cask was hit broadside by the locomotive at a velocity of 131 km/hr (81 mph). Normal

265
placement of the cask on its shipping trailer resulted in an impact of

the top of the locomotive frame 20.3 cm (8 in) below the center! ine of

the cask. Figure 8 is a photograph obtained from the high speed films.

The underframe impact against the cask caused two local indentations

where the ends of the underframe I beams made contact. These were approximately 2.5 cm (1 in ) deep on the outer shell but did not propogate to the interior shell. The underframe impact imparted a spin to

the cask causing it to roll into the locomotive superstructure. The

cask attained a horizontal velocity of about 20 m/s (65 ft/s) in about

0.1 second and the trailer structure was completely wrapped around the

locomotive in about 0.2 second.

The results of the full-scale tests confirmed the analyses results. In both tests the behavior predicted by both the analytical analysis and

the scale models was observed. The correlations between analyses and

full-scale tests are discussed further below.

DISCUSSION

The high speed films from both tests were digitized in order to obtain

kinematic data for making comparisons with the analyses. Post-test

comparisons of the hardware were also made. Figure 9 illustrates the

results of the lumped parameter model for the velocity-time history of

the cask as well as the results from the full-scale test. As can be

seen, the results agreed quite well. The model not only predicted the

time duration of the impact but also the velocity the cask would have

upon contacting the hard target.

The finite element model results for this test proved to be somewhat

conservative in that they overpredicted the "mushrooming" on the

impact end of the cask by about a factor of two. This is attributed

to a number of conservatisms in the model. The eighth-scale test for

this head-on impact produced results which very closely predicted the

results of the full-scale test. The deformation pattern on the impact

end of the model cask was virtually identical to what was observed in

the full-scale test.

The finite element model developed to analyze the grade crossing test

also proved to be conservative as it overpredicted damage to the cask.

This again is attributed to assumptions made in formulating a 2-dimensional model for a 3-dimensional problem. The finite el ement model

,

nevertheless, gave very good indications of what the cask response

would be. It indicated that the corner of the locomotive underframe

would be crushed and that the cask would roll up into the superstructure and sustain some deformation in the area of contact with the

underframe. The results also indicated that the deformations would not

be severe enough to cause the cask to be breached or to seriously

threaten its containment.

The one-eighth scale locomotive and cask models for the grade crossing

test gave excellent results in terms of predicting damage to the fullscale hardware. Figure 10 is a composite photograph showing the full266
scale and model casks after testing. Both casks exhibited indentations

where the longitudinal underframe members impacted the cask. Because

of the odd shape of the indentions, it is difficult to make quantitative comparisons. However, it is estimated that the deformation depth

in the outer shell of the casks agreed within about 15%. Neither the

full -scale nor the model cask had any detectable distortions of their

inner cavity.

CONCLUSION

The analysis techniques that have been briefly discussed in this paper

have proved to be very effective methods for predicting the response

of shipping casks subjected to very severe and mechanically complicated

impact environments. Lumped parameter modeling was found to give very

good results for the overall system response. The finite element calculations were found to give conservative results in that they over- predicted deformations to the casks. This is attributed to conservative

assumptions in the model formulations, the results, however, are still

considered quite good and useful in that they provide the analyst with

much insight ito the mechanics of the problem and the response of the

hardware.

Physical scale modeling has proved to be a very practical and reliable

method for the analysis of complicated problems such as those discussed

above. Complicated and severe hypothetical accident situations can

be investigated with a high degree of confidence that the results will

very closely parallel what would happen in the real situation.

267
REFERENCE

1. Yoshimura, H. R., Pope, R. B., Huerta, M., and Nelson, R. H.,

"Environmental Impact of Accidents Involving Radioactive Materials

Shipping Systems", U. S. DOE Environmental Control Symposium,

November 1979, Washington, DC.

2. Yoshimura, H. R., and Huerta, M., "Full-Scale Tests of SpentNuclear Fuel Shipping Systems", International Atomic Energy Administration Paper No. IAEA-SR-10/17, July 1976.

3. Huerta, M., Analysis, Scale Modeling, and Full -Scale Tests of a Truck Spent-Nuclear-Fuel Shipping System in High Velocity Impacts

Against a Rigid Barrier , Sandia National Laboratories, Albuquerque,

NM, Report No. SAND77-0270, April 1978.

4. Huerta, M., Analysis, Scale Modeling, and Full -Scale Test of a Railcar and Spent-Nuclear-Fuel Shipping Cask in a High-Velocity Impact

Against a Rigid , Sandia National Laboratories, Albuquerque, NM,

Report No. SAND78-0458, June 1981.

5. Huerta, M., and Yoshimura, H. R,, A Study and Full -Scale Test of a High Velocity Grade Crossing Accident Involving a Locomotive and a Spent-Nuclear Shipping Cask , Sandia National Laboratories,

Albuquerque, NM, Report No. SAND79-2291, (to be published).

6. Gabriel son, V. K., and Reese, R. T., SHOCK Code User's Manual, A

Computer Code to Solve the Dynamic Response of Lumped-Mass Systems , Sandia National Laboratories, Livermore, CA, Report No. SCL-DR-69-

98, November 1969.

7. Adams, C. R., Biffle, J. H., Gubbels, M. H., and Huerta, M., A Com- parison of Analytical Techniques for Analyzing a Nuclear-Spent-Fuel

Shipping Cask Subjected to an End-On Impact, Sandia National

Laboratories, Albuquerque, NM, Report No. SAND80-1870, June 1981.

8. Key, S. W., Beisinger, Z. E., and Krieg, R. D., HONDO H - A Finite

Element Computer Program for the Large DeformatiorT Dynamic Response

of Solids, Sandia National Laboratories, Albuquerque, NM, Report No.

SAND78-0422, October 1978.

9. Duffey, T, A., Scaling Laws for Fuel Capsules Subjected to Blast,

Impact, and TheFmal Loading, Sandia National Laboratories,

Albuquerque, NM, Report No. SC-RR-70-1 34, May 1970.

10. McGovern, D. E., and Thunborg, S., On the Use of Modeling in a Structural Response Problem , Sandia National Laboratories, ~

Albuquerque, NM, Report No. SC-RR-70-888, March 1971.

11. Murphy, G., Similitude in Engineering, Ronald Press, New York, 1950.

268
ww/jj/aw/m'i//

^ PWvv—

5.

CASK

-I KW/—

Y

TRACTOR

129 Krn/hr

Y

TRAILER

HHVW- NONLINEAR HYSTERESIS COUPLING —VM- LINEAR SPRING

Figure 1. IlTustration of the schematic of a lumped parameter model

for analyzing the impact of a tractor-trailer system into

a rigid barrier. This model provides an estimate of the

velocity with which the cask impacts the hard target.

269
Figure 2. Illustration of the mesh for the finite element analysis.

This figure shows the calculated deformed shape for the

impact-end of the cask.

270
Figure 3. Undeformed and deformed shapes for the mesh used to perform the finite element analysis for the grade crossing

test. The deformed shape is at .015 second.

271
Figure 4. Photographs of the scale models utilized to analyze the

head-on tractor-trailer and the grade crossing tests.

272
Figure 5. Photograph of the full-scale tractor-trailer system.

273
Figure 6. Photograph of the full-scale tractor-trailer system after

the crash.

274

276
TIME, SECONDS

Figure 9. Results from the lumped parameter model and the full-scale

test results for the velocity-time history of the cask.

277
278
RESPONSE OF RADIOACTIVE MATERIAL WASTE DRUMS

TO ACCIDENT ENVIRONMENTS*

R. A. May

G. H. Lamoreaux

L. E. Romesberg

H R . Yo sh imura

Sandia N a t i o nTl Laboratories**

Albuquerque, New Mexico 87185

ABSTRACT ;

Using computer analyses, subscale model tests, and

selected full scale tests, it is possible to predict the

structural behavior of 208 liter (55 gal) drums resulting

from accident environments. This was verified by

analyzing and testing D0T-17C drum arrays containing

simulated contact-handled transuranic waste (CH-TRU) in

simulated accident environments.

This paper briefly describes the results of the static and

dynamic tests using full scale 17C drums and compares them

to the results obtained from subscale tests and computer

analyses. Methods of eliminating or minimizing the damage

to the drums are mentioned. More detailed information can

befoundinRef.[l].

Key words: accident environments; accident response;

computer analysis; contact-handled transuranic waste;

scale model testing; Type A containers; 55 gallon drums.

INTRODUCTION

The Transportation Technology Center (TTC) at Sandia

National Laboratories (SNL) is currently involved in

programs address'ing the transport of nuclear materials.

The structural response of 208 liter (55 gal), 17C drums

containing contact-handled transuranic waste (CH-TRU) is

being evaluated as part of a program to predict the

This work waTs supported by the U.S. Department of Energy

Contract DE-AC094-76-DP00789

.

** A U.S. Department of Energy Facility.

279
response of low-level nuclear waste transportation systems

to accident environments. Early analyses of the entire

transportation system indicated that the drum behavior had

a strong effect on the structural response of the system

and must be included in the evaluation. It is also

desirable to predict the failure of the drums as part of

the assessment of system response in accident environments

to serve as input to environmental impact statements.

In order to determine the adequacy of predicting CH-TRU

drum response utilizing existing computer codes and

subscale models, static and dynamic tests using full scale

drums were conducted. The results of the computer

analyses and subscale tests were then compared to the full

scale data

.

DESCRIPTION OF PROTOTYPE AND SUBSCALE DRUMS

The full scale drums used in the tests were obtained from

Rockwell International's Rocky Flats Plant. This assured

that the drums tested were the same as those used to

package low-level waste. The drum assembly. Figure 1,

consisted of a thin polyethylene bag filled with waste

contained inside a rigid polyethylene liner. This liner

is in turn contained by the 17C drum. Full scale drums

were tested in four configurations: filled with 91 kg

(200 lbs) of simulated combustible waste, filled with

either 227 or 318 kg (500 or 700 lbs) of simulated sludge

waste, or empty. The weights of the filled drums were

representative of those shipped from Rocky Flats.

Scale model drums were simulated by using appropriately

sized, tinplated steel cans normally used for food

packaging. In the tests being reported, 1/4 scale drums

were modeled using #12 cans. The diameters and heights

scaled to within 3 percent, but the material in the scale

model was 15 percent thinner. This was offset due to the

fact that the yield strength of the material was 70

percent higher. The scale model drums were filled to the

appropriate weight with material taken from the prototype

drums or with locally obtained material of similar

composition. The lids were attached to the cans using a commercially available can sealer.

No attempt was made to model the polyethylene bag, rigid

liner, or the lid clamping ring. Prior to the tests, it

was felt that the difference in the results obtained would

not justify the added expense of modeling these secondary

features.

280
ADHESIVE

RADIOACTIVE MATERIAL WHFTE- I, YELLOW- n. OR YELLOW- I I I LABEL AS APPROPRIATE, 2 PLACES, APPROX 180° APART Figure 1. Typical 17C drum, Type A Waste Container with a Rigid 2 . 5-mm-th i ck Polyethylene Liner

STATIC TESTS

The first tests consisted of quasi-static crush tests of

the full scale and subscale drums. The results of the

tests would identify the failure mode and quantify the

load-deflection behavior of the prototype drums. An early

estimate of the adequacy of the subscale models was

obtained by comparing their load-deflection data with the

scaled prototype data. If the correlation had not been

reasonable, the containers could not have been expected to

correlate in the dynamic tests, and a different subscale

model would have been obtained.

The full scale and subscale model drums were tested in

universal testing machines equipped with rigid platens

large enough to assure adequate contact area during

crush. The crush force versus platen displacement was

obtained graphically from recording equipment on the

testing machines. Time lapse motion pictures were also

taken to document the deformations and failure modes of

the drums. The drums were crushed in a radial direction

at a rate of 2.5 cm/min (1 in/min). The maximum crush of

the drums was arbitrarily chosen to be one-half of the

drum diameter.

281
Eight full scale drums were tested along with six 1/4

scale models. Results from the static crush tests of the

full scale containers demonstrated very consistent

load-deflection behavior (Figure 2). The initial crush

phase and the occurrence of lid separation, characterized

by the sudden drop in the crush force, can be seen to be

independent of the contents. The contents and the amount

of free volume in the drum did affect crush stiffness

following lid failure and the onset and severity of

lockup. The behavior of the drums containing either 227

or 318 kg (500 or 700 lbs) of simulated sludge was

virtually identical, while the drums containing 91 kg (200

lbs) of combustible waste tended to be noticeably stiffer.

60000 -I

RADiAL DRUM CRUSH (CM)

Figure 2. Comparison of the Static Load Deflection

Behavior of Prototype Drums - Various Contents

The results of the static crush tests for full scale drums

containing 227 kg (500 lbs) of combustible waste are shown

in Figure 3 with the results of the comparible 1/4 scale

tests, appropriately scaled to the prototype dimensions,

superimposed. Good correlation between the prototype and

the scale model drums can be seen. This correlation was

observed for all the tests.

It was found that the 1/4 scale models could not replicate

the separation of the drum lid from the body that was

observed at approximately 10 percent diametral crush on the prototype drums. This was due to the fact that the

282
prototype drums

while the scale

container body,

very similar to

was attached in

used clamping rings to secure the lid

model lids were rolled and crimped to the

The behavior of the scale model lids was

that of the bottom of the prototype which

a similar manner

.

60000 -

3 40000 H

<o

20000 -

RADIAL DRUM CRUSH (CM)

Figure 3. Comparison of the Scale Load-Deflection Behavior

for 1/4 and Full Scale 227 kg Containers

DYNAMIC TESTS

A series of dynamic tests was conducted following the

completion of the static tests. These tests established

the characteristic deformed shapes of the prototype and

subscale drums and gave quantitative results of the damage

as a function of the impact conditions. Both single and

multiple drum configurations were tested at impact

velocities that would be expected to occur in a severe

transportation accident. The multiple drum configurations

included 8 high x 1 column, 2x3, 3x2 and 8x3 container

arrays. In one series of tests, a closed cell, rigid

polyurethane foam, located between the container and the

target, was used to simulate the impact mitigation

properties of a typical transport container.

All dynamic tests were conducted at SNL's Coyote Canyon

Drop Test Facility. The full scale drums were allowed to

free-fall onto an unyielding target. Since the smaller,

subscale models tended to rotate during free-fall and

impact in undesired orientations, these specimens were

guided to the target using small diameter cables passed

through guides attached to the cans. The target consisted

of a 227 tonne (250 ton) reinforced concrete foundation

283
topped with 10 cm (4 in) of hardened steel plate. In

order to maintain vertical alignment of the waste

containers in the multiple drum drops, frames constructed

of heavy angle iron were utilized. No bulging or

excessive deformations of the frames were observed during

the post-test inspections. Data collected included

measurements of the radial drum deformations, flattened

impact area and, where applicable, polyurethane foam

deformation.

As expected from the results of the static tests, the

correlation between the prototype and the scale model

drums was good. Both the radial deformations and the

general deformed shapes of both the models and prototype

were in agreement. A comparison of the deformed shapes of

a prototype and subscale drum impacted at 47 kph (29 mph)

is shown in Figure 4. The inclusion of the polyurethane

foam had little, if any, effect on the crush behavior of

the drums in the multiple drum array impacts.

Figure 4. Post-test Appearance of the 1/4 and Full Scale

318 kg Containers Following a 47 kph Impact

As was found in the static tests, the separation of the

drum lid could not be visually determined from the

subscale models due to the different method of

attachment. However, after examining the full scale and

subscale static and dynamic tests, it was felt that lid

separation in prototype tests could be predicted from the

284
scale model data. In both the static and dynamic tests,

the lid separation consistently occurred at approximately

10 percent crush. Therefore, any subscale drum which

exhibited more than 10 percent crush after testing would

infer that the full scale drum would open in the same

test. This criterion can also be applied to predict drum

openings from the results of the computer simulations.

ANALYTIC RESULTS

The 8 high x 1 column array configuration was analyzed

using existing computer codes to predict drum damage when

dropped from either 6.4 or 9 m (21 or 30 ft). The first

method used a lumped parameter code [2] to calculate the

crush of each drum and the final array height. The drums

were modeled in the code as a series of masses and springs

which represented the weights and stiffnesses of the drums

and contents. The stiffnesses were obtained from the

earlier full scale static crush tests.

A finite element model using a SNL developed computer code

[3] was also used for damage predictions. In this case

the drums were represented as solid cylinders of

material. Average material properties were used to obtain

the correct drum behavior. These material properties were

determined from the previously conducted full scale static

crushtests[l].

The crush of individual drums in the eight high array was

predicted with reasonable accuracy by both analytical

models. In order to compare the analytical results, which

predict maximum deformations, to the experimental results,

which were final deformations, the former had to be

corrected for the elastic spring-back of the drums. This

was accomplished by subtracting a measured spring-back of

approximately 3.8 cm (1.5 in) from the predicted maximum

deformations to determine the final deformation. The

results of the lumped parameter model and the finite

element model, corrected for spring-back, along with the

full scale and 1/4 scale test results for the 9 m (30 ft)

drop, are shown in Figure 5. The finite element model

slightly overpredicts the crush of the top and the bottom

two drums. This result can be attributed to using a solid

cylinder to represent the drum. The lumped parameter

model gives a somewhat better prediction of individual

drum crush, but no indication of the deformed drum shape.

However, both models give results which are within the

expected repeatability of the tests. Again, it is felt

285
that any drum that has a predicted radial deformation

greater than 10 percent of its diameter would show lid

separation in a. full scale test.

, LUMPED PARAMETER

MODEL

,1/4 SCALE

FINITE ELEMENT

MODEL

DRUM NUMBER (BOTTOM DRUM IS NUMBER 1)

Figure 5

.

Compar i son

Analyt i cal

of Full and 1/4 Scale Test

Results; Eight High Stack,

Results to

9 m drop

CONCLUSIONS

Based on the tests that have been conducted, it is felt

that the structural response of low-level waste drums to

impact environments can be adequately predicted using

analytical and subscale models. Both the finite element

and the lumped parameter models give results that are

expected to be in the range of behavior of the full scale

drums. The failure of the drum closure cannot be directly

observed from the subscale test results or predicted by

the computer analyses, but can be inferred from

experimental data.

Results of tests and analyses indicate that a large number

of drums would be opened in a hypotheth i cal accident

situation. This is caused primarily by the drums near the

286
front being crushed by those in the rear of the multiple

drum arrays. The damage to the drums could be reduced by

providing partitioning to separate the drums thus

eliminating the damage caused by the inertial effects of

the rear drums.

REFERENCES

1. May, R. A., Romesberg, L. E., Lamoreaux, 6. H., and

Sutherland, S. H., "Analysis, Scale Modeling and Full

Scale Tests of Low-Level Waste Drum Response to

Accident Environments," SAND80-2517, Sandia National

Laboratories, Albuquerque, NM (to be published).

2. Gabrielson, V. K., and Reese, R. T., "SHOCK Code Users

Manual, a Computer Code to Solve the Dynamic Response

of Lumped-Mass Systems," Sandia National Laboratories,

Livermore, California, Report No. SCL-DR-69-68,

November 1969.

3. Key, S. W., Beisinger, Z. E., Krieg, R. D., "HONDO II,

a Finite Element Computer Program for the Large

Deformation Dynamic Response of Axisymmetric Solids,"

Sandia National Laboratories, Albuquerque, New Mexico,

Report No. SAND78-0422, October 1978.

287
DESIGN OF PACKAGING FOR TRANSPORTING TRANSURANIC

CONTAMINATED WASTES*

L. E. Romesberg

Sandia National Laboratories

Albuquerque, NM 87185

S. H. Sutherland

Sandia National Laboratories

Albuquerque, NM 87185

G. H. Lamoreaux

Sandia National Laboratories

Albuquerque, NM 87185

R. G. Eakes

Sandia National Laboratories

Albuquerque, NM 87185

Abstract: Contact-handled transuranic (CH-TRU) waste continues to be

generated and temporarily stored at a number of locations in the United

States as a by-product of national defense programs. The Transportation

Technology Center at Sandia National Laboratories has assumed the lead

lab responsibility for development of safe, efficient, licensable, and

cost-effective transportation systems to be used in the management of

this waste. The TRansUranic PACkage Transporter (TRUPACT), a Type B packaging, will be transported by rail or truck and will be compatible

with Type A packagings used by waste generators, interim storage sites,

and repositories. Developing an efficient interface with each facility

is being given a high priority

CH-TRU waste is typically packaged in steel drums, fiberglass reinforced plywood (FRP) boxes, or a variety of steel boxes. The waste

typically consists of pi utonium contaminated metal scraps, sludge, paper,

filters, and other materials resul ting from production of weapons grade

nuclear materials and from reprocessing operations. The activity of

the waste is low with the maximum container surface dose rate being

less than 200 mrem/hr.

TRUPACT is required to be a Type B packaging since larger than Type

A quantities of some radionucl ides (particularly pi utonium) may be transported. Waste packagings inside of TRUPACT are not required to be

Type A and could be any standard industrial container that facilitates

handling. The TRUPACT must provide structural and thermal protection

*Work sponsored by the U. S. Department of Energy under Contract

DE-AC04-76-DP00789.

288
to the waste in accident environments as specified in DOE 5480.1 Chg.

3 (5/1/81), DOT regulations 49 CFR 173 and NRC regulations 10 CFR

71. No radiation shielding or internal heat removal mechanism is necessary

for this waste.

The TRUPACT consists of inner and outer steel sheathed tubul ar frameworks

separated by polyurethane foam. Stainless steel plate is used internal ly

to facilitate decontamination. The inner containment structure has a hinged door that uses elastomeric seals. The polyurethane foam in the

walls and ends of the package provides impact energy mitigation and

fire protection. The outer tubular framework of the TRUPACT is covered

with carbon steel plate and has a steel door. Stainless steel puncture

plates are included on the inner surface of the outer tubular steel

framework to prevent puncture of the inner containment cavity.

Preliminary design of the packaging has been completed and effective

methods have been employed to prevent failure under both the normal

handling and hypothetical accident conditions. This paper will describe

design criteria adopted, mechanical and physical features of the packaging, and packaging features included to meet regulatory test conditions.

In addition, analyses that havebeen conducted will be summarized, scale

model tests that havebeen performed will be discussed, and the program

schedule through delivery of first production units will be outlined.

Key words: Nuclear waste, contact-handled waste, transportation. Type

B packaging, packaging, overpack, truck transport, rail transport, structural analysis, thermal analysis, puncture analysis, testing, scale model

testing.

Introduction

The Contact-Handled Transuranic (CH-TRU) waste transportation system

under development at Sandia National Laboratories is known as the TRUPACT

(TRansUranic PACkage Transporter). The TRUPACT is a Type B packaging

concept which is being developed to transport a variety of low-level,

transuranic contaminated waste forms.

Type A packagings are normally used to transport low concentrations

of radionuclides and must be shown to withstand, without loss of integrity, test conditions which simulate environments encountered in

normal transportation as specified in 49CFR173.398, Section b. A Type

B packaging, in addition to satisfying the Type A packaging requirements,

must also be shown to withstand, without loss of package integrity,

the hypothetical accident conditions of transportation given in Section

c of 49CFR173.398.

A Type A packaging may be used for containing and transporting a Type

A quantity or less of radionuclides. Greater than Type A quantities

289
I

may only be transported in a Type B packaging. The Type A and Type

B quantities of a particular nuclide are determined by the nuclides

transport group. Specific information concerning transport groups and

Type A and B quantities is given in 49CFR173.389 and 49CFR173.390.

Type B packaging is required for transporting CH-TRU waste since greater

than Type A quantities of some radionuclides (particularly plutonium)

may be present in individual or groups of CH-TRU waste containers.

The TRUPACT i s being designed to meet the existing Type B requirements.

An awareness of possible changes in the regulations will be maintained;

the effect of such changes on the TRUPACT design will be examined to

determine if design alterations are required.

The TRUPACT conceptual design is currently a large metal box which

will be available in both rail and truck transported versions. The

packaging dimensions and capacities are:

Rail Configuration

Overall Dimensions

Length: 23 ft, 2 in. (7.1 m)

Width: 10 ft, 0 in. (3.0 m)

Height: 10 ft, 11 in, (3.3 m)

Inside Dimensions

Length: 17 ft, 2 in. (5.2 m)

Width: 7 ft, 8 in. (2.3 m)

Height: 8 ft, 7 in. (2.6 m)

Weights

Empty Packaging: 38,000 lb (17.2 tonne)

Cargo Capacity: 32,000 lb (14.5 tonne)

Gross Weight: 70,000 lb (31.7 tonne)

Truck Configuration

Overall Dimensions

Length: 24 ft, 8 in. (7.5 m)

Width: 8 ft, 0 in. (2.4 m)

Height: 9 ft, 0 in. (2.7 m)

290
Inside Dimensions

Length: 18 ft, 8 in. (5.9 m)

Width: 6 ft, 0 in. (1 .8 m)

Height: 7 ft, 0 in. (2.1 m)

Weights

Empty Packaging:

Cargo Capacity:

Gross Weight:

28,000 lb (12.7 tonne)

17,000 lb (7.7 tonne)

45,000 lb (20.4 tonne)

Truck Transport Design Basis

The transport semi-trailer and tractor are being designed to operate

as a legal system throughout the United States, i.e., at a Gross Vehicl

e

Weight (GVW) of 73,280 lb (33.3 tonne) or less. The weight distribution

will be such that the limiting loads of 32,000 lb (14.5 tonne) for

a tandem axle, and 9000 lb (4.0 tonne) for a single steering axle are not exceeded. Most states now have GVW limits of 80,000 lb (35.3

tonne) or more; however, the practical limit for a tandem axle semi-trailer

with a three-axle tractor is about 78,000 lb (35.4 tonne). In states

that use "bridge formulas", the distance between the steering axle and

the rear axle of the trailer is used to limit the allowable GVW.

The most restrictive limits for a five-axle tractor and semi-trailer

combination according to a 1979 chart published by the Truck Trailer

Mai,nufacturing Association are

The position of the packaging on the trailer will be adjusted to uniformly

distribute the load between the tractor and semi -trailer axles. The

Type B package will be attached to the trail er bed using standard container

mounting hardware (as recommended by the International Organization

for Standardization (ISO)) which has been installed into the trailer

frame to provide rigid attachments. The tiedown hardware will be designed

to provide a static strength equal to 2, 5, and 10 times the maximum

weight of the loaded packaging in the vertical, transverse, and longitudinal directions, respectively (10CFR71.31 (d)). Design loads for

packaging analysis will be determined using the test conditions discussed

in the introduction material.

Rail Transport Design Basis

The rail car transported TRUPACT option will provide a system that can

be used throughout the U.S. without restrictions. To permit unrestricted

Length - 55 ft, 0 in. (16.8 m)

Width - 8 ft, 0 in. (2.4 m)

Height - 13 ft, 6 in. (4.1 m)

291
interchange of railcars, the Plate B Envelope dimensions imposed by

the American Association of Railroads (AAR) have been selected. The

rail cars used will have a minimum GVW of 200,000 lb (90.8 tonne) and

a minimum cargo capacity of 140,000 lb (63.5 tonne), i.e., two rail

TRUPACTS loaded to their maximum rated capacity.

The TRUPACT packagings will be attached to the rail car using moveable

ISO tiedowns located in the rail car fl atbed surface. The tiedown hardware

will be designed to provide a static capacity of 2, 5, and 10 times

the maximum weight of a loaded packaging in the vertical, transverse,

and longitudinal directions, respectively, (10CFR71 .31 (d)). The overall

length of the rail car will be approximately 60 ft (18.3 m). Design

loads for packaging analysis will be determined using the normal and

hypothetical accident test conditions referenced in the introduction.

Reference Design Description

The TRUPACT concept is illustrated in Figure 1. The structure con- sists of inner and outer tubular-steel frameworks separated by rigid

polyurethane foam and sheathed with steel plate. Package weight is

minimized by using a ductile high strength, low alloy steel in both

frameworks.

The outer framework is covered with thin mild steel or stainless steel

sheet. The packaging cavity is lined with stainless steel because

of its ductility and ease of decontamination. The inner structure

is made secure by closing and bolting into place a hinged 5 in. (13

cm) thick door which also has an internal tubular steel framework and

is filled with foam. This door is sealed with dual elastomeric seals.

An exterior door is attached to the outer framework with hinges, is

36 in. (90 cm) thick, utilizes a single elastomeric seal, and is also

bolted in place for transport.

There is approximately 36 in. (91 cm) of foam in the packaging ends

and 14 in. (36 cm) and 12 in. (30 cm) in the walls of the rail and

truck configurations, respectively, to provide thermal protection and

to absorb impact and puncture energy. Puncture protection is provided

by placing ductile stainless steel plates on the inside surface of

the outer framework to distribute the penetrator energy over a large

area of low strength polyurethane foam.

Cargo loading and unloading will be accommodated by using either a rolling pallet or roller conveyor system on the floor of the TRUPACT,

Heavy handling equipment cannot be used inside the packaging because

the floor covering is thin steel sheets supported on and attached to

widely spaced tubular steel framework members and the rigid foam between

the framework has a relatively low compressive strength. Figures 2 and

3 show the rail and legal weight truck versions, respectively , of TRUPACT

loaded with 2x3 arrays (six-packs) of 55-gallon drums.

292
Failure Prevention Design Details

The four primary assaults which could cause package failure addressed

during the TRUPACT preliminary design are impact, puncture, thermal,

and pressure. Secondary conditions possibly 1 eading to package failure

not addressed in this paper are vibration and immersion. Vibration

and immersion can generally be handled primarily by selection of proper

materials or fabrication methods.

Impact failures which might occur during normal or hypothetical accident

test conditions are prevented (1) by selecting steel materials with

high ductility, (2) by surrounding the inner structure with rigid polyurethane foam having a low density (6 lbs/ ft^ or 96 kg/m^), and (3)

by configuring the framework geometry to distribute impact loads and

retain the original structure's geometry particularly in the closure

seal area. The inner framework is lined with stainless steel sheet

having a thickness of 0.13 in. to 0.20 in. (.3 cm to .5 cm) which

is a highly ductile material that can absorb very large deformations

without loss of integrity. Similarly , the frameworks are of high-strength

low-alloy steel having a yield strength of 80 Ksi (550 MPa) which

when continuously supported by the inner or outer steel covering can absorb 1 arge deformations without failure. The inner and outer frameworks

are keyed into the foam during foam placement thus alleviating the

need for additional mechanical connections between the frameworks. Shear

strength in low-density foam is low but the keying action of the frame

members causes a tremendous amount of foam to be 1 oaded during a dynamic

event and eliminates large concentrated loads on the inner frame. The

frameworks are also configured to redistribute any concentrated loads

to other portions of the frames by using a triangular framing pattern.

Achievement of puncture resistance in the TRUPACT presents a very severe design problem. The hypothetical accident condition for puncture requires

that the packaging retain its integrity when dropped 40 in.(l meter)

onto a 6 in. (15 cm) diameter rigid steel pin. The reference design

for preventing failure during a puncture event has continuous sheets

of stainless steel on the inside surface of the outer frame. During

the puncture event these stainless steel plates are displaced into the

rigid foam, which backs the plates, and spreads the load over a large

area of low compressive strength foam. The soft foam alters the puncture

load to change it from an impulsive load to one of long duration,

thus, lowering the magnitude of the peak force. The outer sheet of

steel and thin layer of foam material on the outside of the stainless

steel puncture plates also tend to blunt the punch edges and increase

the effectiveness of the puncture plates.

The effects of the severe thermal environment presented by the totally

engulfing pool fire test at 1475*^ (800*0 for 30 minutes will be

negated by careful foam selection. The 12 to 14 inches (30 to 36

cm) thickness of foam in the TRUPACT walls provide a large amount of

293
insulation. One dimensional thermal analysis has indicated that an

8 in. (20 cm) thickness of the foam type currently being considered

will prevent significant temperature rise on the inner surface after one hour of exposure to the engulfing fire.

Changes in external pressure, upward to 1.7 atmospheres or downward

to 0.5 atmosphere, must also be analyzed to evaluate their effect on the structure. The pass/fail criteria for the packaging response to

the pressure change is that the containment vessel will suffer no loss of

contents. The walls of the TRUPACT are flat panels but the manner

of construction produces a sandwich panel with excellent rigidity. The

foam core is covered on the inner and outer surfaces with the metal

pi ates and framework members. Deformations predicted by analyses indicate

that yielding may occur but failure is not apparent.

In summary, the key to the success of the TRUPACT design is the mutual

interactions of the steel covered framework members, the puncture resistant steel plate on the inside of the outer framework and the foamed-inplace polyurethane foam in the package walls. The rigid foam is an essential el ement in this design and, as indicated in the above paragraphs,

must be selected carefully to perform a variety of functions.

TRUPACT Analyses Performed

Compliance of the TRUPACT concept with federal regulations must be

demonstrated by analysis, testing (either full-scale or with scale models

and components) , or an appropriate combination of each. In this development program evaluation by analysis was emphasized since the TRUPACT

is a relatively large and complex structure and procurement of full-scale

and, to a lesser extent, quarter-scale models of the package for test

purposes is prohibitively expensive and time consuming. A fairly extensive

test program, however, was pursued concurrently with the analysis of

the package to confirm the validity of numerical predictions as they

were obtained. Some results of the analyses are presented immediately

below while prominent features of the test program are discussed in

the subsequent section. Presently only the rail version of the package

has been analyzed but the truck version is similar enough in concept

such that similar results are expected when it is finally investigated.

The analysis of the TRUPACT was limited principally to estimating the

effects of the following four assaults to the package:

1) impact of the fully loaded package on a rigid target following a 30 ft (9 m) free fall;

2) impact of the fully loaded package on a rigid steel pin

following a 40 in (1 m) free fall;

294
3) exposure of the fully loaded package to a totally engulfing UyS^F (800*'C) fire for 30-minutes, and

4) subjection of the package to a 1.7 atm. overpressure.

According to the regulations, the accumulated damage sustained by the

package following sequential application of the first 3 assaults must

be determined. In the analyses, however, the assaults were considered

individually. The results of the analyses and tests suggested that

the extent of accumul ated damage would not be substantially more severe

than that obtained by each individual assault alone.

The impact following the 9 m free fall was considered in the first

analyses of the TRUPACT. Three different impact orientations (endon, side-on, and center of mass over corner) were investigated numerically. Initially, hand calculations utilizing a simple rigid mass

model of the TRUPACT 's inner frame and cargo were performed to estimate foam characteristics and thickness requirements needed in the package's ends and sides to ensure the inner frame was well protected

in end-on and side-on impacts. Following these scoping calculations,

consecutively more complex three-dimensional finite element analyses were performed using the ADINA structural analysis code. Some features

of these various analyses are indicated in Table 1.

The most sophisticated (as well as most meaningful) analyses of the

TRUPACT for the three impact orientations were done utilizing the finite

element model which employed 3 dimensional truss structures for the

inner and outer fameworks, 3 dimensional solid elements for the foam,

and either truss elements or concentrated (nodal) masses for the cargo.

Some results obtained in the analysis of the model are given in Table

2.

In addition to estimates for deformation, the ADINA analyses indicated

strain levels which might be achieved during the impacts. The strain

levels reached in the inner frame of the TRUPACT are of particular

interest since, if these strains are limited, it is probable that the

integrity of the inner structure will be maintained. The analyses predicted slight yielding in some inner frame members for the end-on and

side-on impacts and significant yielding in the corner impact. Apparently

this result is an artifact of the conservative finite element model

analyzed since no inner frame yielding was evident in quarter-scale

drop tests (which are described below) and inner frame yielding ceased

when the skin on the inner frame of TRUPACT was incl uded in the computer

model as thin shell elements.

295
TABLE 1. TRUPACT Analyses Series for Three 9 m Drop Impact

Orientations

T MODEL COMPONENTS

SIMULATED ANALIMPACT YSISOuter

Frame Foam

Inner

Frame Cargo

END -ON

SIDE-(

CORNER

4

1

2

3

1

2

3-D Truss

Structure

3-D Truss

Structure

3-D Truss

Structure

Noni inear

Spring

Truss Elements

Truss Elanents

3-D Solid

El ements

Non1 inear

Spring

Rigid Mass Rigid Mass

3-D Solid

El ements

Nonl inear

Spri ng

3-D Solid

El ements

3-D Truss

Structure

3-D Truss

Structure

3-D Truss

Structure

Truss Elements Modal Mass

3-D Truss

Structure

3-D Truss

Structure

Nodal

Masses

Truss

El ements

Truss

El ements

Rigid Mass Rigid Mass

Truss

El ements

Truss

El ements

Rigid Mass Rigid Mass

Nodal

Masses

TABLE 2. Numerical Predictions for Foam Crush in

Impact Situations

1 Impact

I Orientation

1 END-On

I

I SIDE-ON

I

I CORNER

Foam Yield

^ Stress, psi (MPa) in (cm)

50 (0.345)

100 (0.690)

100 (0.690)

Amount of Foam Crush

% of foam available

5.2 (13.2)

1.7 ( 4.2)

21 (53)

14

21

51

296
The numerical evaluation of the puncture resistance of the TRUPACT was

done using both finite el ement analyses and hand calculations employing

an approximate theoretical trea-bnent of the problem. Of the two, the

latter approach was emphasized since the finite element analyses were expensive and the hand calcul ations gave excellent results particularly

when substantiated by a parallel test program.

In the approximate theoretical treatment of the puncture problem fully

plastic circular stainless steel plates supported on a foam foundation

were considered. Expressions were developed for the amount of strain

energy in the plate and energy expended in deforming the foam as the

punch deflected the system. By equating the sum of these energy ex- pressions to the total change in gravitational potential energy of

the system during the puncture test, it was possible to obtain an estimate

of the peak deflection and strain levels obtained in the plate as a function of plate thickness and yield stress of the steel and foam.

Based on this theory and correlations with the concurrent test program,

it was estimated that a puncture plate thickness of about 0.5 in (1.3

cm) would be sufficient to prevent penetration and unacceptable deformation in a fully loaded rail TRUPACT punch-drop test.

Thermal analyses have been performed using the Aerotherm Charring Material

Thermal Response and Ablation (CMA) Computer Code.* Foam samples have

been tested for a number of candidate material s to obtain input parameters

for the CMA code and to screen the materials by comparing thermal

degradation characteristics. Samples have been tested in furnaces and

in a wall panel simul ation fixture. Data are still being collected and

analyzed but suitable materials appear to be obtainable. The requirements

for the foam are foam-in-place fabrication, minimum density , low thermal

diffusivity, high char yiel d, fine grain char, and dimensional stability.

There are also additional considerations related to impact and puncture

performance that must be considered. Preliminary analyses indicate that

foam materials of the type being tested will limit the interior surface

temperature rise in the 1/2 hour regulatory fire to about 40**F if

the foam thickness is 4 inches (10.2 cm) or 0**F if 8 inches (20.3

cm). As indicated previously, the TRUPACT wall thickness exceeds 8

inches (20.3 cm)

.

The structural response of the TRUPACT under a 1.7 atm. overpressure

was evaluated using one of the more sophisticated ADINA finite element

models analyzed in the impact situations but modified to allow beam

type response of the frame members. The results of the calculation

indicated that 1 ocal ized yielding may occur in a few frame members

but the overall deformations sustained would not compromise the package'

s

integrity.

*User" s Manual : Aerotherm Charring Material Thermal Response and Ablation

Program (Vers ioTr3) , Vol . I , Report No. UM-/U-14, Aerotherm Corporation,

Mountain View, CA, 1970.

297
At this time, the TRUPACT response to a 0.5 atm. underpressure has

not been determined but it is believed this loading is not as severe

as the overpressure environment.

TRUPACT Tests Conducted

An extensive test program has been pursued during the TRUPACT development with the goals of validating the concept, obtaining data for

comparison with numerical analyses of the package, and providing visual

evidence for public information purposes. Many impact and puncture

tests have been performed with quarter scale models of the TRUPACT

which include the predominant structural features of the package. A

series of drop tests were conducted with individual and arrays of eighth-,

quarter-, and full-scale Type A waste containers to determine their

response to impacts and to aid in developing parameters for modeling

cargo loadings in the numerical analyses. Numerous puncture tests with

circular plates were also performed to enable correlations to be made

between test results and theoretical predictions.

The quarter scaleTRUPACT models had linear dimensions one fourth those

of the corresponding full-scale values and weighed, when loaded with

scaled waste containers, about one-sixty-fourth the weight of a fullscale fully loaded package. Each model was subjected to one or more

9 m drop-impact tests in different orientations including end-on, sideon, center of mass over corner, end-edge, side-edge, corner slapdown,

and end-edge slapdown. Although the models sustained appreciable exterior

damage, particul arly those subjected to three or more impacts, virtually

no distortion of the package interiors was evident. This resul t suggests

that the TRUPACT exterior structure provides sufficient protection for

the inner structure in impact type situations. In addition, excellent

comparisons between theoretical predictions and experimental results

were obtained. For instance, one end-impact test of a model resulted

in 1.3 in (3.2 cm) crush-up of the package end which corresponds to

5.0 in (12.8 cm) full scale. The numerical prediction for this same impact situation was 5.2 in (13.2 cm) full scale.

The first phase of the puncture test series included dynamically punch

loaded clamped edge, 9 in (23 cm) and 18 in (46 cm) diameter, plates

both with and without foam backing. These tests verified that scaling

laws apply to the puncture phenomena. The approximate theoretical treatment of the puncture event was also found to predict the results of

the punch tests reasonably well. Based on these tests and associated

analyses, it was possible to estimate the puncture plate thickness

required in the TRUPACT to prevent penetration. Puncture plates were

included in two of the TRUPACT models and subsequent drop-puncture

tests with these model s demonstrated that a satisfactory puncture resistant design was obtainable with about 0.5 in (1.3 cm) thick stainless

steel plates.

298
Thermal tests have been conducted on a number of comrnercially available rigid polyurethane foam materials. Screening tests were performed

to measure response of a foam cube exposed to a uniform temperature

for a specified time interval . Test objectives were to identify degradation characteristics (especially the tendency to mel t) , identify physical characteristics of thecharred foam, and establ ish performance rankings of candidate foams (char yield and integrity). In these tests

eleven candidates were tested and three were recommended for wall-fire

testing. The objective of the wall-fire tests is to simulate a pool

fire environment using radiant lamps to heat candidate foams in a stainless

steel enclosure and to develop one-dimensional heat and mass transfer

data. These tests are currently being conducted and will be reported

on at a later date.

Program Schedule

The program schedul e is currently being revised to emphasize final design

of the truck configuration and provide a test prototype in FY 83 and

five production units in late FY 83 and early FY 84. Final design

of the rail configuration wil 1 begin after the truck version is completed

and will be finished in FY 84 with prototype hardware available in

FY 86 and production units available about FY 88 or 89. A program

schedule for TRUPACT is shown in Table 3.

299
o _i =3 1—

i

< UJ

h- -J

1- »— <

_J

o: o o o: Q Q 1—1 oo. UJ

1—

UJ o UJ UJ <

Q. f— 1— UJ > oo

UJ < <c UJ < < en UJ < H0£ o o en: o o <: q: 1—

(

Ht—

1

o •—1 Q 1—

(

3 < 00 00 z 1—4 OO

(—1 U1—4 UJ u. U. UJ U- Q 3 1— OO 1— z 1— t—t 1—1 (— 1—

4

ct: o (/> hoo

>- o »- < h- 00 Q < 1- «C UJ oo z UJ o ai >• UJ q; Q q; a: < 1— UJ =5

_i UJ o. us _j q: UJ CL. UJ IE I—

«c <i: o =D o «< <C O =3 o Z >^ z o. z a. UJ O _J o _i O o -J

<: UJ UJ ca o < UJ UJ Q£ o Q. »—

1

1—

t

=) »—

4

q: o < a: a: o "sc d: >- a: < QC < 1—

>- a. o >- Q- Q 00 Z H- 1— q: H- Ol o h- on 1—

UJ

1—

UJ Oi no u. U- o o < <00 Ol Ol.

300
RIGID FOAM

TUBULAR TRUSS

FRAMEWORK

(INNER AND OUTER BOX)

RIGID FOAM

OUTER BOX

Figure 1. Photograph of a TRUAPCT Model, Partial Cutaway Showing

Internal Structure

PAYLOAD LIMIT 32.000 LBS

EMPTY WEIGHT 38.000 LBS

SHOCK AND

THERMAL

ISOLATION

48 55-

STAINLESS GALLON DRUMS

OUTER DOOR ^TEEL LINED (8 SIX PACKS),

WITH SEAL CAVITY

23-2"

W/DOOR CLOSED

*USEFUL SPACE DIMENSION

*7'-8'

Figure 2. TRUPACT Containers (10 Ft Wide) Showing Railroad Configuration With Six Packs

301
302
SESSION VI

HIGHWAYS

CHAIRMAN: J. C. SHANG

GENERAL AMERICAN RESEARCH DIVISION

PLANNING TO PREVENT FAILURE IN THE

TRANSPORTATION OF HAZARDOUS MATERIALS

E.J. CantiHi

Department of Transportation Planning & Engineering

Polytechnic Institute of New York

New York, New York 11201

Dino Rossini

Technical & Medical Forensic Consultants, Inc. West Hempstead, New York 11552

Abstract: The prevention and mitigation of consequences in the

transportation of hazardous materials are discussed. Efforts

in the mitigation, or "emergency response" aspects, are overemphasized at the expense of preventive efforts.

Planning for the prevention of incidents requires two areas

of effort: knowledge of past failures, and a preventive outlookin design, construction, operation, and maintenance.

There is a general lack of data base for preventive efforts.

Incident informationis usually used solely for training emergency response personnel.

An example is discussed, that of the George Washington Bridge

incident of August 7, 1980. ?7hy a valve failed. Why it took

.~ $4 plumber's tcsz. plug—by purest chance and coincidence

to solve such a potentially catastrophic situation. An example

of how little questioning there was of valves or other components of vehicles or guideways, in all the transport modes.

The problems of moving hazardous materials in bulk form, a major problem on the railroads. Derailment, turnover, puncture as a common sequence. The application of limited solutions;

shields as crutches. Ignoring the systems approach.

The need for a system-v/ide approach ("Transportation System

Safety") in planning, based on feedback from construction,

testing, operations (incidents) and maintenance. The need for

original, specific designs for each special purpose.

Key Words: Hazardous materials; transportation of hazardous

materials; transportation system safety.

In safety engineering, there are only two approaches to improving safety: that of attempting to prevent incidents from happening; and that of mitigating , or reducing the severity, of the

accidents which surely will happen. ^- In the activity of transporting hazardous materials, more et..ort

(and money) goes into the mitigation aspect, in this case

•emergency-response' activities, than into prevention. At tne same time, however, because of the unsystematic, scattergun

approach taken to emergency-response training, overall ettorts

even here are inadequate.

Prevention involves planning, and planning ahead requires

knowledge of what has happened in the past. In this respect

305
there is little knowledge, little 'data base' available concerning how accidents have happened in the past. What informaterion has been collected on past 'failures' of the system,

past incidents, is used primarily for training emergency re- sponse personnel.

This is a laudable use of data, but greater efforts in prevention should reduce the need for emergency response efforts.

In an incident on the George Washington Bridge, on August 7,

1980, a vehicle carrying liquefied petroleum gas sprang a leak.

The leak was eventually stopped and the incident caused no injuries or damage.

However, in considering the 'system' of transporting such

hazardous materials on public highways, a number of questions

can be raised: —Why has no study been made of how and why the GWB incident

occurred, and of how it can be prevented in the future? —Why did a specific valve fail? —Why did it require the extraordinary coincidence of a policeman, who moonlights as a plumber's helper, recognizing that a

$4 test plug (which he promptly purchased) would stop the leak?

The answer to all these questions is: because of lack of

planning. The National Transportation Safety Board, which investigates all major accidents in all transportation modes,

would not investigate an accident which did not result in

death or major injury. Therefore the lessons to be learned

from a potential disaster go unlearned. The National Highv?ay

Traffic Safety Adininistration . vrhich has had ref^ponsibility

for improving the design of vehicles, is undergoing a loss of

many of its powers, as weak as they were. The solution to the

spcific problem on the Bridge was left up to Coincidence, or Providence, or whatever.

In considering how to prevent failures in the transportation of

hazardous materials, engineers in recent years have fallen back

on concepts of 'system safety', which is as much a planning

tool as it is an engineering tool. The interest in system

safety concepts reached a peak with the work done at the Polytechnic Institute of New York from 1976 to 1980 on creating

a methodology called 'transportation system safety', with

applicability to all transportation modes.

The first task in applying this approach is to define the system

being dealt with, and all its parts, subsystems, and components.

In the case of defining the transportation of hazardous materials by highway, the basic system is composed of man as driver;

machine , the vehicle; and the environment , composed of the road,

the roadside, signs and markings, other traffic, rules and

regulations, weather and light conditions, etc.

The difficulties with a system as complex as that of moving

hazardous materials by highway immediately surface: there are few standardized vehicles; every driver has different physical

capabilities, training competence, and psychology; and the

'environment' includes a host of variables, each of v;hich has

an impact on safety.

And yet, by making the identification process as detailed as possible, we can see immediately where there is a lack of needed

306
data, or knowledge, or standards of design or operation; where

there is duplication or lack of training. For instance, fire

fighters were never taught that you don't put out a fire that

involves a tank vehicle carrying LPG. The common name for this

condition is "blevey", for Boiling Liquid Expanding Vapor Explosion. Until a number of firefighters were killed, the profession

did not learn that if the tank is venting, you don't put it out,

you let it burn. If it is not venting, you use a fog spray.

You don't approach the tank from either end, because the ends

are its weakest points.

Is it possible that engineers and chemists didn't know this 30

years ago? Obviously they did. No one asked them, so they

didn't tell the right people.

On the railroads, most incidents involving hazardous

materials relate to derailments. Derailments relate directly

to poor maintenance of both track and vehicles. Maintenance

problems represent poor planning. Maintenance records are always used as an example of a source for planning new units, new

components, new subsystems, and new systems. But did the designers, of the BART system consult the operators of the New York

City Subway System? The example of constant feedback, of learning

from the errors and failures of the past, is often used but rarely followed.

On the highways problems of highway maintenance are compounded

by problems of vehicle design and operation and by the inadequacy of training of drivers and materials handlers.

Our dedication to 'reacting' to emergencies means that we do

little planning i.u prevent the emergency situation. And then

we don't prepare our emergency crews sufficiently anyway.

The Federal Government publishes lists of hazardous

materials but the manufacturers must tell the constructors of

the special-purposes vehicles what their requirements are, and

they must also have a hand in driver training, the training of

the people who load and unload materials onto and from trucks,

and the emergency response personnel who must be trained in the

proper handling of thousands of different chemical compounds which

can escape and burn or explode.

Some of this is done, of course, by the largest of chemical

companies, which own their own fleets of trucks and train their

own drivers. But most trucks are owned by owner-drivers, and

there were more than 27,000 hazardous-materials incidents involving trucks last year in the U.S.

The systems approach applied to this problem means true planning

thinking ahead to what might happen and what could happen; of

what the probabilities are of failure of a component, a vehicle,

or a human being, and eliminating the hazard in the design process.

The procedure of looking for accident cause, and patching up

a tank or a valve or changing a highway route, under the assumption that another accident of the same type will be avoided, is

completely incorrect. No two accidents or incidents ever occur

in exactly the same way.

Systematic thinking—and planning—is the only solution to preventing failures in the complex activity of transporting hazardous

materials on the roads.

307
CARGO RIDE EVALUATION ON A ROAD SIMULATOR

C. R. Forton

Fruehauf Corporation

Detroit, Michigan 48232

Abstract: A combination vehicle such as a tractor-semitrailer is a dynamic system which responds to road surface

irregularities. When the natural frequencies of the system

coincide with the road frequencies, near resonant conditions exist which might result in cargo damage or driver

fatigue or both. A technique is presented in this paper

where a road simulator is used to compare the effects of

road surface, speed, and suspension on ride and trailer

floor accelerations.

Fruehauf Road Simulator is a tire actuated electrohydraulic system where real roads can be simulated under

controlled conditions. The spindle accelerations are measured on the road. The transfer function between the tires

and spindles are measured on the road simulator. Then, by

a compensation technique, the effective road profile can be

calculated. When the trailer is excited with this effective road profile, the response of it will be similar to

that on the road.

Once the effective road profile of a representative

road surface is obtained, it could be used to study the

effects of speed, loading conditions, suspension design

and wheel base on ride and cargo accelerations.

At present, there is no universal specification for

maximum acceleration on cargo. The reason for this may be

because there are infinite variations in loading locations,

speed, road surface and cargo mounts. As an indication of

the dynamic environment to which the cargo will be subjected, the PSD of the vertical accelerations of the floor

at various locations are calculated from acceleration response. Again, the effects of modification, including

load location, can be easily studied.

Thus, the road simulator could be effectively used to

compare various design changes in terms of cargo accelerations under controlled conditions in the laboratory.

Key words: Effective road; frequency domain; frequency response function (FRF); power spectral density (PSD); spatial PSD; system resonances; temporal PSD; time domain.

308
One method for studying the response of a heavy duty

vehicle subjected to dynamic road inputs is reproducing

those inputs in the laboratory. The Fruehauf Corporation

Road Simulator is composed of four tire actuated electrohydraulic actuators and a fifth wheel fixture (composed of

two electrohydraulic actuators) which takes the place of a tractor (see Figure 1) . The methodology presented here is

aimed towards heavy duty trailers, but is applicable to

most size vehicles.

A technique has been developed whereby an "effective"

road is input to the vehicle through vertical actuators

such that the dynamic response will be similar to that obtained on the road (1)*. Once this effective road has been

developed, a number of options are available for using it

which will be discussed later. First, some insight into

effective road development is in order.

Several steps are required to develop an effective

road as shown in Figure 2. The vehicle is driven over a selected route at constant speed and the spindle and fifth

wheel accelerations are recorded on analog tape, which represents the desired response to be reproduced on the road

simulator. Accelerations at floor level or other locations

may be recorded as well, which provide another means of

verifying dynamic response in the laboratory. The field

data is then digitized using analog to digital converters

and a digital computer. Once digitized, the data is then

edited to remove erroneous data such as tape drop outs or

large transients.

The next step is to take the same vehicle used to record the data and determine its Frequency Response Function

(FRF) on the road simulator. Simply stated, an FRF is a measure of the gain and phase characteristics between an

input (e.g., vertical tire actuator displacement) and output (e.g., acceleration response at spindle) as a complex

function of frequency (see Figure 3) . It should be noted

that an FRF is a description of a linear system. Since vehicle components such as leaf springs and tires are nonlinear, the inputs used to excite the vehicle for FRF determination should be composed of roughly the same frequencies and amplitudes as the measured road inputs. Hence,

the input used for FRF determination will be random in

nature, but statistically similar to the road profile being

developed

.

For a multi-input, multi-output system there would be

one FRF for every input-output combination, which is best

handled in matrix form as shown in Figure 4. The Yi(f)'s

in Figure 4 represent spindle response, the Xi(f)'s rep-

*Refers to reference at end of paper

309
resent actuator drive signals, and each Hjj (£) represents

the FRF between the respective signals.

In matrix notation, this may be written as

Y(f) = H(£)X(£)

Through a series o£ matrix manipulations, X(f) can be

solved £or, thus

X(£) = H(£)-^Yd(£)

where Yd(£) is the Fourier trans£orm of the desired response

and X(£) is being sought (1)

.

This calculated drive signal, X(£) , based on the system

transfer function and desired response, can then be used to

excite the vehicle on the road simulator and the actual

spindle responses can be recorded simultaneously. If the

actual response of the vehicle is not suitably close to the

desired response, the drive signal can be iteratively modified until the actual and desired responses are in agreement . In the effective road development technique just described, the test vehicle was used for obtaining the road

profile. Once the road profile is derived and stored on

digital tape in the form of vertical actuator stroke inputs,

the test vehicle is no longer required to reproduce the

effective road. Any vehicle similar to the test vehicle may

be excited by the effective road and its response will be

similar to the response obtained if it were driven over the

same road as the test vehicle.

A convenient way for summarizing random time history

response is through the use of power spectral density (PSD)

.

A PSD statistically resolves a time history into its frequency components, with the ordinate being squared amplitude

per temporal frequency, and the abcissa temporal frequency.

[Temporal frequency is cycles per second or hertz (Hz) . Unless stated otherwise, the use of the term PSD will indicate

temporal PSD throughout this paper.] A PSD is actually the

mean square value of all the amplitudes occurring within a narrow frequency band, or bandwidth, divided by the bandwidth. Hence, by indexing the bandwidth throughout the entire frequency spectrum of interest, a continuous curve is

obtained

.

Referring now to Figure 5, the solid curve is a PSD of

vertical floor acceleration at the front of a trailer at

floor level being driven down a fairly rough asphalt road at

40 mph. Note that the amplitude is in g's squared per

hertz. The dashed curve is a PSD for the same trailer being

excited by the corresponding effective road on the road simulator. The PSD's are nearly identical up to approximately

35 Hz. The deviation is due to the physical limitations of

the actuators. However, the major structural modes occur

310
below 20 Hz so that this becomes inconsequential.

Figures 6a, b, and c are time history plots for three

different one-second time intervals from which the PSD's of

Figure 5 were obtained. These are presented to illustrate

the difference between time domain and frequency domain

data. Additionally, these three plots indicate the accuracy

with which dynamic responses can be reproduced in the laboratory. (It should be noted that the plots presented in

this paper are in no way conclusive; rather, they are presented as illustrations of possible effects due to different

vehicles, loads, road surfaces, etc., on cargo ride.)

It can readily be seen that the effects on cargo ride

due to different vehicles, as well as design changes and

load variations within the same vehicle, can be compared by

exciting with the same effective road and recording the

corresponding responses at floor level.

As an illustration of the preceeding statement, the

following examples are presented. A 45 foot van trailer

with a concentrated 50,000-pound load at the center of the

trailer was excited on the road simulator. The input was

the effective road of the fairly rough asphalt road at 40

mph as previoulsy mentioned. Vertical floor accelerations o were recorded and the PSD's calculated. The load was then

uniformly distributed and the test repeated. The two curves

in Figure 7 are PSD plots with the solid curve representing

the first load condition and the dashed curve representing

the second load condition. The several major peaks occurring before 7.5 Hz represent the trailer free body modes,

i.e., roll, bounce, pitch, etc. The highest peak which ^ occurs at 5.2 Hz for load condition one is lowered to 4.6

Hz for load condition two, and the amplitude is reduced as

well. However, the peak at 2.8 Hz remains at the same frequency for both load conditions, and the amplitude becomes

larger for the second load condition. Hence, depending on

cargo critical frequencies, the second load condition may

or may not be desirable.

Since a PSD is a squared function, it is often convenient to obtain a linear plot so that a linear comparison

may be made. This can be accomplished by multiplying the

PSD amplitude by the bandwidth and taking the square root.

The result is an rms plot as shown in Figure 7b.

A second example is presented in Figure 8 which compares the difference in vertical floor acceleration at the

rear of the trailer between two different trailer suspensions (same trailer in both cases) . The solid curve represents the response obtained with a conventional leaf

spring suspension, and the dashed curve is the same for an

air suspension. The curves indicate the reduction in acceleration levels obtained with an air suspension.

311
Up to this point, the effective road discussed has

been a time history reproduction of a particular stretch

of road at one speed. Chronological events including transients such as chuck holes, railroad tracks, chatter bumps,

etc., can be reproduced. However, if general road surface

characteristics alone are of interest, it is advantageous

to develop effective roads which statistically represent

particular classes of roads. This is accomplished by using

a frequency domain effective road development procedure,

which is similar to the time domain effective road development technique previously discussed. The resultant "frequency domain" effective road used to drive the actuators is

still a time history, but it does not reproduce the road inputs in chronological order. Rather, the order is random,

with amplitude and frequency content similar to the road

being developed. Hence, one frequency domain effective road

could represent smooth concrete roads, another represent

rough asphalt roads, etc. In this manner, the effects of

road surface roughness can easily be studied.

Road surfaces are most commonly categorized by spatial

PSD's of profilometer recordings. A spatial PSD is given

in terms of spatial frequency and spatial spectral amplitude

(e.g., cycles per foot and feet squared per cycle per foot)

as opposed to temporal PSD which is in terms of temporal

frequency and temporal spectral amplitude (e.g., cycles per

second and feet squared per cycle per second) . For a given

constant velocity, a spatial PSD may be converted to a temporal PSD by multiplying the spatial frequency by the vehicle velocity, and dividing the spatial spectral amplitude

by the velocity, and vice versa.

Shown in Figure 9 are spatial PSD's of a rough asphalt

road (solid curve) and a smooth concrete road (dashed

curve). Note that the trends are similar (i.e., high amplitude at low frequency and low amplitude at high frequency) despite the individual differences. These plots

were obtained by calculating the temporal PSD's from effective road actuator stroke inputs and then converting to

spatial PSD's. Due to nonl inear it ies (which are compensated for by the effective road development technique)

,

these will differ slightly from spatial PSD's of profilometer recordings of the actual roads, but the mean square

values will be approximately the same. (The mean square

value is equivalent to the area under the PSD.) As a demonstration of cargo ride effects due to road surface

roughness variation, both of these frequency domain effective road profiles were used to excite the same trailer

under the same loading condition. Corresponding trailer

vertical floor acceleration PSD's for both of these inputs

are shown in Figure 10. The curves indicate that cargo

ride is less severe on smooth roads at most frequencies.

312
However, this is not always the case. Depending on load

distribution and speed, the vehicle pitch mode can be excited due to tire resonances on a smooth road. A rough road

tends to wash out the tire resonances thus eliminating the

severe pitching.

Two additional advantages of a frequency domain effective road are that the wheelbase of the test vehicle and the

speed of the effective road may be changed.

To test two vehicles of varying wheelbase with the same

effective road, the phase relationships between actuator inputs can be mathematically adjusted to reflect the corresponding change in wheelbase. To do this, the PSD of the

frequency domain effective road drive signal is calculated,

then it is "filtered" by the appropriate time delay matrix.

The effective road drive signal is then regenerated based

on the shape of the filtered effective road PSD. (Correction for wheelbase is also possible with a time domain effective road.) The effects on cargo ride due to a 5% change

in wheelbase are dramatized in Figure 11.

As with wheelbase correction, to change the speed of a frequency domain effective road, the temporal PSD is first

calculated. Then, based on the original speed of the effective road, the temporal PSD is converted to a spatial PSD.

The spatial PSD is then converted back to a temporal PSD

based on the desired new speed, and the effective road drive

signal regenerated. Due to the mathematics involved, decreasing the effective speed results in loss of high frequency data, addition of low frequency data, and the effective frequency resolution increases. On the other hand, increasing the speed results in just the opposite effects,

i.e., the addition of high frequency data, loss of low frequency data, and a decrease in the effective frequency resolution.

Shown in Figure 12 are PSD's of the same effective road

surface input before and after a 5 mph speed increase. From

the plots it can be seen that increasing the speed increases

the frequency of a given peak, while at the same time the

amplitude is decreased. The advantage of being able to

change the speed of an effective road is that critical vibration speeds may be determined. In effect, a speed sweep

test may be conducted by successively changing the speed of

the same effective road, exciting the test vehicle, recording the response, and thereby, determine the speeds at which

the system resonances are at a maximum. Figure 13 graphically illustrates the results of such a test.

In summary, the value of a road simulator to define

dynamic cargo environment has been outlined. Except for

measuring accelerations on the road, all testing is conducted in a stationary environment where vehicle dynamic response is easily observed and measured. The effects of car313
go load variation, test vehicle component variation, and

different test vehicles of the same wheelbase may be studied

by using a time domain or frequency domain effective road.

To determine the effects of road surface roughness, wheelbase, or speed variations, a frequency domain effective road

is preferred. For each variation tested, the vertical floor

accelerations may be recorded and analyzed using PSD techniques.

A final step, which has not been discussed, would be to

utilize the vertical floor accelerations, which define dynamic cargo environment, for component cargo testing. Since

cargo configurations, as well as the impedance at the cargotrailer floor interface are so variable, the cargo of interest could be excited on a shaker table using the vertical

floor acceleration PSD's recorded on the road simulator to

define the input. The dynamic response of the cargo itself

could then be recorded and analyzed.

Reference

(1) B.W. Cryer, P.E. Nawrocki , and R.A. Lund, "A Road

Simulation System for Heavy Duty Vehicles", paper

760361 presented at the SAE Automotive Engineering

Congress, Detroit, Michigan, February 23-27, 1976

314
FIG. 1 - FRUEHAUF CORPORATION ROAD SIMULATOR

315
316
GAIN

(Gs/IN.)

E 99

E-ei

FREQUENCY (HZ

FIG. 3a - FRF GAIN BETWEEN TIRE INPUT DRIVE SIGNAL

AND AXLE SPINDLE RESPONSE

E ea

a. 40

PHASE

(DEG.)

1.S0

1.80

9.69

9,99

FREQUENCY (HZ)

FIG. 3b - FRF PHASE BETWEEN TIRE INPUT DRIVE SIGNAL

AND AXLE SPINDLE RESPONSE

317
•

•

•

Hn(X)iH,260

H2,(/),H22(X)

• • • H,n69

H2„(7)

Hn,(/).Hn2(7) Hnn60

x,60

X26Q

Xn(X)

FIG. 4 - FRF MATRIX EQUATION

SPECTRAL

AMPLITUDE

(GsVHZ)

e.ee e.se i.ee i.se a.ee a^sc s.ee s.se 4.M 4.se s.ee FREQUENCY (HZ) ^

FIG. 5 - PSD's OF ACTUAL ROAD RESPONSE

VS. ROAD SIMULATOR RESPONSE

318
ACCELERATION

(Gs) 0.00

s.ee s.ie 5.20 s.39 5.4d 5.50 5.60 5.70 5.80 5.90 6.00

e 09

TIME (SEC.)

FIG. 6a - TIME HISTORY OF ACTUAL ROAD RESPONSE

VS. ROAD SIMULATOR RESPONSE

E 00

1.00

0.80

0.60

0.40

0.20

ACCELERATION

<G»> 0.00

-0.80

-0.40

-0.80

-1.00

ACTUAL ROAD

A

h \

1 1'

•VIK>1

It V ] T 11 J vr

; % VK aJ

- \*

\ A JS ' V rt '•AT

V\

V

- \ >

>•

8.45 2.45 2.45 2.45 2.45 S.46 2.46 2.46 2.46 2.46 2.46

E 02

TIME (SEC.)

FIG. 6b - TIME HISTORY OF ACTUAL ROAD RESPONSE

VS. ROAD SIMULATOR RESPONSE

319
ACCELERATION

IGs)

-0.60

-1.00

TIME (SEC.)

FIG. 6c - TIME HISTORY OF ACTUAL ROAD RESPONSE

VS. ROAD SIMULATOR RESPONSE

C-02

E-03

SPECTRAL

AMPLITUDE

(GsVHZ)

E-04

E-es

0.00 0.85 0.50 0.75 1.00 l.ZS 1.50 1.75 8.00 8.85 8.50

FREQUENCY (HZ) ^

FIG. 7a - PSD OF VERTICAL FLOOR RESPONSE —

LOAD VARIATION COMPARISON

320
E-«l

i.ee

0.70

0.60

0.50 RMS

AMPLITUDE

(Gs) e.40

0.30

0.80

e.i0

e.00

0*00 0 •SS 0.75 1.00 1.25 1.50

FREQUENCY (HZ)

FIG. 7b - RMS OF VERTICAL FLOOR RESPONSE —

LOAD VARIATION COMPARISON

E-0a

E-03

SPECTRAL

AMPLITUDE

(GsVHZ)

E-04

0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50

FREQUENCY (HZ) ^

FIG. 8a - PSD OF VERTICAL FLOOR RESPONSE —

TRAILER SUSPENSION COMPARISON

321
E-0i

0.8e

e.7e

0.50 RMS

AMPLITUDE

(Gs) 0^40

0.30

0.20

0.10

0.00

LEAF SPRING SUSPENSIO^1

K 1

Ol 1

1 1 1

* * 1 H—

4

1 1

1

1 1

1

' H

h

\

Jl 1 1 ,'f.

;

;

V

'« A' ' A 1/^ /

K00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50

FREQUENCY (HZ) ^

FIG. 8b - RMS OF VERTICAL FLOOR RESPONSE —

TRAILER SUSPENSION COMPARISON

E-01

E-02

E-03

SPATIAL

SPECTRAL

AMPLITUDE

(FTVCYC/FT)

E-04

E-05

E-06

E-07

£-02 E-01

SPATIAL FREQUENCY (CYC/FT)

FIG. 9 - SPATIAL PSD's OF EFFECTIVE ROAD INPUTS

E 00

322
E-oe

E-03

SPECTRAL

AMPLITUDE

(GsVHZ)

E-04

E-«5

e.M 0.25 e.50 0.75 1.00 1.S5 1.50 1.75 8.00 8.25 2.50

FREQUENCY (HZ)

FIG. 10 - PSD OF VERTICAL FLOOR RESPONSE —

ROAD SURFACE COMPARISON

E 01

SPECTRAL

AMPLITUDE

(GsVHZ)

9.00 e.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50

FREQUENCY (HZ) ^

FIG. 11 - EQUAL INPUT AMPLITUDE INPUT PHASE DIFFERENCE

(EQUIVALENT TO 5% CHANGE IN WHEELBASE)

323
SPECTRAL

AMPLITUDE

(INVHZ)

O.ee 0.85 0.50 0.75 1.00 1.S5 1.50 1.75 8.00 8.85 8.50

FREQUENCY (HZ) ^ ®*

FIG. 12 - SPECTRAL DENSITY OF SINGLE ROAD SURFACE

AT DIFFERENT VEHICLE SPEEDS

RMS

AMPLITUDE

(Gs)

0.00

0.00 0.10 0.S0 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 E 01

FREQUENCY (HZ)

FIG. 13 - RMS OF VERTICAL FLOOR RESPOhJSE —

SPEED VARIATION COMPARISON

324
HIGHWAY DESIGN AND MAINTENANCE FOR TOMORROW'S TRAFFIC

B. M. McCarthy

The Asphalt Institute

6200 Montrose Road

Rockville, Maryland 20852

Abstract: The condition of the roadway surface plays a significant

role in preventing damage to cargo and to increasing safety in the

shipment of goods by ground transportation. Increasing traffic volumes

and loads have led to changes in pavement design concepts to adequately

handle the increased stresses occurring in the roadway. Additionally,

because of these increased stresses, proper preventive maintenance has

become a major concern of highway engineers. This problem is complicated by the rapid rise of inflation and declining revenues available

for pavement maintenance which has resulted in the highway system

deteriorating at an alarming rate in recent years. It will be shown

that programmed maintenance that includes timely resurfacing before

rapid deterioration begins will extend the pavement life more econom- ically than in the case where pavement resurfacing is delayed. The

consequences of deferred action are increased fuel costs, increased

operator costs, increased damage to cargo, increased safety problems,

rerouting of commercial traffic and general user dissatisfaction. A

pavement management system is essential if we are to obtain the most

efficient use of the highway dollar and establish those roads in

immediate need of repair.

Key words: Asphalt concrete; California Bearing Ration (CBR) ; DAMA;

design period; Equivalent Axle Load (EAL) ; highway system; pothole;

rehabilitation; Resilient Modulus (Mr).

The shipping of goods and services to every corner of the country and

the individual freedom of mobility Americans enjoy can only be possible

with an efficient, well-maintained system of roads. The total vehicle

transportation industry — including moving of goods, services and

people and the construction and maintenance of the road system represents more than 18 percent of the nation's Gross National Product (GNP).

Forty percent (407o) of the world's passenger cars and trucks are found

in the United States. To say that a good highway system is vital to our economy is an understatement since 65% of the country's communities

are without rail service and must rely on highway transportation for

goods and services. Additionally, we see more and more miles of track

abandoned each year primarily due to poor track condition which is the

result of years of deferred maintenance.

325
To adequately and efficiently handle the 154 million vehicles that are registered in the United States, the roadway surface plays a significant role in preventing damage to cargo and to increased safety in the

shipment of goods. Included in this fleet of vehicles are 32 million

trucks hauling goods and services to virtually every comer of the

nation. Additionally, it should be noted, there are over 3.5 million

trucks sold each year in the United States and sales of large heavy

duty trucks has been increasing.

For a pavement to perform its function, it must be properly designed

and built to avoid the highway engineer's nemesis the "pothole." With

increases in both the volume and weight of traffic, design concepts

have also changed from granular bases to Full-Depth asphalt designs.

And methods of pavement design are going from an empirical approach to

a more rationale approach that is based on a mechanistic model that

considers material properties and failure criteria. The Asphalt Institute has developed a procedure based on current knowledge of multilayered elastic theory, fundamental material properties, and realistic

failure criteria. The method utilizes the computer program DAMA to

develop design curves that determine proper pavement thicknesses. As

with other pavement design procedures, the factors traffic, subgrade,

environment and pavement materials are analyzed,

I

The traffic analysis determines how many vehicles of different types

are expected to use the pavement. Traffic considerations then include

present traffic, the design period, and a growth factor. Knowing the

types and numbers of vehicles expected to use the road, we then express

that data in a single number known as the EAL , Equivalent Axle Load.

The total number of Equivalent Axle Load application contributed by a single vehicle is called its truck factor. By determining the truck

factor of all the vehicles of all types expected to use the road during

the design period we arrive at the design EAL.

Next, we must consider the strength of the subgrade that will support

the pavement and traffic. The strength of the subgrade is characterized

by the subgrade ' s Resilient Modulus, Mj.. Mj. is a ratio between stress

and strain -- the stress exerted on the subgrade soil and the resulting

strain produced in the subgrade. If other more familiar soil strengths

are known, such as the CBR (California Bearing Ratio) they can be used

to estimate the soil's Resilient Modulus.

After considering traffic and subgrade characteristics we must consider

the environment that will influence the pavement. The computer program

allows for all types of climatic conditions and the design charts in

manual consider environments where frost is a factor which is one extreme condition.

326
The final factor that must be considered is that of the pavement

materials to be used in the construction of the road. Several different

materials are considered for the surface and base which include asphalt

concrete, emulsified asphalt mixtures, and untreated aggregate.

Utilizing these factors as input design, charts are presented that

allows one to design an asphalt concrete pavement to support the

anticipated loads. The design chart is a log-log plot with design EAL

values running horizontally and subgrade Resilient Modulus values

running vertically.

The Asphalt Institute's design procedure does afford the design

engineer the tools to design a pavement for the anticipated traffic

and soils conditions that will last for the design period. However, it

should be recognized that the usual thickness design period is

selected for about twenty years and that if more or heavier traffic

loads use the road than were expected, the road wears out sooner than

the design period. If we arbitrarily extend the pavement life beyond

its design period by not maintaining the road properly and if we experience heavier loads than expected, our system will change from the

f inest-in-the-world road system to a two-million-mile obstacle course

of ruts, bumps, cracks and potholes.

Bad roads waste billions of gallons of fuel every year. They damage

vehicle tires, brakes, and suspension systems and take a heavy toll

in injuries and deaths. Inferior roads swell transportation costs,

which raises the price of everything at the market place. They lead to

millions of hours of costly delays that interfere with both work and

leisure time. Unfortunately, the problem is not limited to isolated

areas, but rather we see signs all over the United States.

To appreciate the scope of the situation, consider that there are approximately two million miles of paved roads in the United States -- a little more than half of the country's total road mileage. Of those

two million miles, 31 percent carry 87 percent of the nation's traffic.

This 31 percent includes America's major highways -- the interstate

system, the arterials, and the collectors. The Federal Highway Administration took a look at these roads in 1975 and found that 100,000

miles were already in "poor" condition and required immediate attention.

The report also noted that each year 22,000 miles of highway in "fair"

condition deteriorate into "poor" condition and 4,000 miles in "good"

condition fall into "fair" condition. From the report a goal of

rehabilitating 26,000 miles each year was established. That goal was nearly achieved in 1976 but by 1980 less than half of the goal was reached adding more mileage to the backlog. Remember, these figures

represent only 31 percent of the paved roads in the United States.

327
The local service roads comprise the other 69 percent and are generally

in worse condition than the major highways.

Part of the problem is tied to our inflationary spiral with tremendously

increasing costs for repair. Highway construction and repair costs

have risen 50 percent faster than general wholesale prices. Another

part of the problem is highway financing. In terms of constant dollars,

the funding available for rehabilitating our major highways has declined drastically.

Another part of the problem is how pavements are affected by vehicle

axle loads. As stated earlier, if more or heavier traffic loads use the road than were expected, the road will wear out sooner than the

design period. The weight and configuration of the axles along with

the number of repetitions is what determines the pavement life or time

to first maintenance. For example, 2,500 cars put the same load on a road as one legally loaded truck and one overloaded truck may be as harmful as two or three legally loaded trucks. Pavements usually fail

due to fatigue which means that it takes many applications of loads

before failure. As either the amount of the load or the number of axle

loads increase, the pavement life decreases. As the pavement thickness

increases, its ability to carry more and heavier loads also increases.

Damage to the pavement increases very rapidly as the load is increased.

For example, one 18,000 lb. load causes almost ten times more damage to

the pavement than does a 10,000 lb. load. To illustrate, we will assume that one 18,000 lb. load on a single axle with four tires causes one unit of damage. Then a semi-trailer with a 10,000 lb. front steering

axle and two single 18,000 lb. load axles loaded to maximum loading

would have 2.1 damage units with a pay load of 16,000 lbs. If the same truck was overloaded to 20,000 lbs. the pay load would increase 25

percent but pavement fatigue damage would increase almost 50 percent to

3.1. Taking it one step further, if the same truck was loaded to

24,000 lb. axle loads it would cause almost three times the damage as the 18,000 lb. axles and increase the pay load by only 75 percent.

Going the other way, research has shown that a 42,000 lb. evenly loaded

tri-axle will cause only one unit of damage.

Another form of pavement failure is permanent deformation or rutting

due to loading in the wheel paths causing an overloading of the subgrade. The thicker the pavement the less load on the soil. Therefore,

weaker soils require a thicker or stronger pavement.

Recognizing that pavements deteriorate with loading conditions and age

the lifecycle of a pavement shows a general decline for its design

life. During the first 8 to 10 years change in pavement condition is

328
minimal. Only after 15 or more years does a typical pavement cross the

line from good condition to fair. At that point the pavement has gone

through 75 percent of its design life and its condition has declined

about 40 percent. To return the pavement to good or like - new

condition, some rehabilitation is required. If that rehabilitation is

deferred, deterioration accelerates, cracks quickly become potholes

and surface irregularities degenerate into rough surfaces. Within a short time, pavement conditions drops another 40 percent from fair to

poor or very poor. At this point the pavement requires complete

reconstruction. This means that each dollar you're saving by deferring

rehabilitation will cost you $4 to $5 a short time later. Obviously,

deferred maintenance costs more.

Conversely, timely maintenance or rehabilitation saves money in the

long run and extends the design life of the pavement. A hot-mix

asphalt concrete overlay placed at the right time can increase the

pavement life by more than 60 percent. Therefore, a timely rehabilitation program should be established to extend the pavement life which

will result in significant savings to the road users.

A rehabilitation schedule should be planned around the design life of

each pavement, with rehabilitation done before the pavement condition

crosses the line between good and fair. Once the schedule has been

established it should be communicated to decision makers so that

adequate funding will be provided. The consequences of deferred action

are increased fuel costs, increased safety problems, rerouting of

commercial traffic, damage to cargo, and general user dissatisfaction.

Also deferring rehabilitation costs more. For example, compare two

jurisdictions with average pavement in the good to fair range. One

opts for an overlay program immediately and begins construction of 100

miles per year while the other defers action for 5 years in order to

build up treasury reserves and with the thought that the pavement would

last that long. When jurisdiction number two does begin to upgrade

their system the costs are substantially more per mile and a 10-year

summary would indicate that jurisdiction number one actually upgraded

1000 miles at one -half the cost that jurisdiction number two expended

to upgrade 500 miles.

When people hear the term "worn roads" they immediately think of

potholes. Unfortunately, potholes are a sympton of a problem almost

beyond repair. A crack in the road is the same as a crack in the roof.

In both cases, one should repair the minor damage before it becomes

more extensive and more expensive to correct. We should maintain our system of highways in the United States to provide the most economical

use to the highway-user.

329
THE FAILURE OF MANHOLE COVERS ON TANK

TRAILERS DURING ROLLOVER

R.D. Ervin

Highway Safety Research Institute

The University of Michigan

Ann Arbor, Michigan 48109

Abstract: Accidents involving the rollover of bulk petroleum transport tankers in Michigan have frequently involved the wholesale failure of the manhole cover assemblies mounted at the top of the tank.

Such failures result in the rapid spillage of large quantities of

liquid and, often, are the occasion of large fires. This paper describes a research effort by which the pertinent accident experience

was defined and full-scale rollover experiments conducted to establish

the mechanisms by which manhole cover failures occur. Results show

that the internal fluid pressures prevailing inside the tank vessel at

the moment of ground impact are three to five times higher than the

pressure level currently specified in federal regulations which mandate

the proof testing of manhole cover assemblies. Recommendations are made for a type of proof test which would assure the level of manhole

cover strength needed to prevent failure.

Key words: Fire; fuel spillage; manhole cover; rollover; tank trucks.

The spillage of fluid product in highway accidents involving petroleum

transport tankers derives primar^ily from tank failures induced in roll- over impacts. Indeed, data gathered in a recent two-year period in

the State of Michigan show that only one in 25 product spill incidents

occurred due to a non-rollover accident. In a research study [1] con- ducted by the Highway Safety Research Institute of The University of

Michigan, a review was made of tanker accidents reported by the Michigan Fire Marshall's Office to identify mechanisms of tank failure

occurring in rollover accidents. Upon observing that the most common failure mechanism involved the manhole covers which are mounted on the

top of each tank compartment, a set of experiments was then conducted

to establish the impact pressure conditions to which manhole covers are subjected in a rollover.

Review of Tank Failure Data: Using the State of Michigan Fire Marshall's Incident Reports for 1977 and 1978, 33 accidents were identified for study in which the tanker overturned with the possibility of

damage to the tank. Selection criteria included (1) vehicle overturn,

(2) tank capacity in excess of 5,000 gallons, (3) a single-trailer

articulated vehicle or a "doubles" vehicle. Straight, local delivery

330
vehicles were not included. For each accident, the damage to the involved tank was determined through either direct examination of the

vehicle, interviews with trucking company staff, or from State Police

incident reports.

In 25 of the 33 instances, the tank was found to have been significantly damaged. The level of damage ranged from gouges and dents to cave- in of an entire side of a doubles train.

Twenty-three of the vehicles had suffered loss of product by means of

the following failures:

13 cases - manhole cover dislodged or leaking

5 cases - split in tank weld seam

4 cases - puncture in tank wall

1 case - both split seam and puncture

Manhole Cover Failures: Manhole cover failures ranging from total dislodging of the cover to a sustained leakage after rollover have been

observed under a variety of rollover impact conditions. Manhole cover failures were experienced with tanks which struck rigid pavement as well as snow banks. Shown in Figure 1, for example, are tanks having

Figure 1. Flattened sidewalls of a double tanker which rolled over on the roadway.

the distinctly flattened sidewalls which result from rollover onto a rigid pavement, the situation most likely to dislodge manhole covers.

Shown in Figure 2 is a photo taken at the accident scene of a burned

tanker which has lost two of its manhole covers after rolling over on

a Detroit expressway. One of the covers can be seen laying on the

ground near the tank.

331
Figure 2. Accident scene showing gasoline tanker that has suffered

dislodgement of two manhole covers, with ensuing fire.

Although the anecdotal information illustrated that a problem exists,

a statistically-sound basis for inferring the role played by manholecover failure is not possible, since the available data are so sparse

and since reporting of specific types of manhole-cover failure was not

done consistently. Nevertheless, the complete dislodging of manhole

covers appears to constitute a quite hazardous mode of tank failure

since the fluid load is released at such a high flow rate that a "river" of fuel is created. The "river" flows rapidly along the

natural drainage profile of the roadway, posing a particular threat to

other vehicles either involved in, or stalled by, the accident. If the

fuel is ignited, of course, the rapid flow of the "river" implies a rapidly advancing flame front. Fuel releases involving tank seam

split, puncture, and the like, appeared to result in more containable

fires and to pose less risk to persons since the spillage rates of

fuel were much less than those experienced in the event of manhole

cover dislodgement.

Study of the Integrity of Manhole Covers: Shown in Figure 3 is a closeup photo of a dislodged manhole cover having a design such as has

been popular in Michigan, and in much of the U.S., for use on tankers

transporting gasoline and fuel oil. The manhole cover assembly is

normally situated on top of each tank compartment, between two protective rails. The device shown in the photo serves as a covering over

the compartment's manway and has installed a "filler cap" for conventional gravity loading of the tank. Also, the assembly includes

devices to limit internal pressure and to provide for the recovering

of vapors when the tank is loaded through the bottom. ^

332
Figure 3. Typical manhole cover assembly.

The key design feature which has led to concerns for manhole cover integrity involves the clamping band by which the cover plate is fastened

to the flanged opening to the compartment. The photo, Figure 3, shows

distortion in the clamping band by which this manhole cover became detached from the tank. The integrity of such manhole-cover assemblies

and their attachment hardware is currently addressed by the Code of

Federal Regulations #CF49-1 78.341 -3 which states:

(a) ' Each compartment (of a tank vehicle of type MC-306) in excess of

2,500 gallons capacity shall be accessible through a manhole of at least

11 X 15 inches. Manhold and/or fill opening covers shall be designed to

provide secure closure of the openings. They shall have structural capability of withstanding internal fluid pressures of 9 p.s.i.g. without

permanent deformation. Safety devices to prevent the manhole and/or

fill cover from opening fully when internal pressure is present shall

be provided.

The accident experience cited in the preceding section led to the hypothesis that the 9 psi internal pressure requirement of the regulation

was inadequate for assuring that manhole covers would not become dislodged in rollover impacts.

Experimental Program of Rollover Impact: In order to test the stated

hypothesis, a set of experiments was planned to determine the maximum

level of internal fluid pressure which is likely to occur in a gasoline

tanker which suffers a rollover impact against a flat paved surface.

A set of four individual experiments was conducted using full-size

gasol ine tank trailers.

333
Experiment #1 - The first test was conceived as representing a severe rollover event such as would derive if a rapid steering maneuver was attempted such that the tank trailer could gain a large level of roll

velocity before its tires came off of the ground. Computerized simulation was employed to predict the roll and elevation trajectory of the

vehicle. The final impact attitude is shown in Figure 4, indicating

that in a very severe rollover event of this type, the tank arrives at

a rather steep roll attitude by the time ground contact is made. The

impact condition further entails a final angular velocity of 2.6 rad/

sec and a vertical velocity at the mass center of 16.2 ft/sec.

'Figure 4. Tanker orientation at moment of impact in computerized

simulation of severe rollover event.

A full-scale kinematic equivalent of this impact condition was achieved

through use of the test rig shown in Figure 5. By this arrangement,

the vehicle was set up to achieve a free roll motion about a selected

longitudinal axis which was near the center of the tanker's axles. The

figure shows certain auxiliary vehicles which were used to hold down or rigidly locate elements of the pivot mechanism. The vehicle is perched

upon two upright poles which support the tank by means of rollers set

into box-like fittings at each end of the tank. Each roller, which is

fastened to the pole, bears against an inclined plate such that the

vertical load of the tanker tends to push the pole away from the tank.

Upon suddenly releasing tension on the overhead cable, the poles are

both pushed out and the tanker falls in a free rotation about the pivot.

Since the tank strikes the ground with a contact force which passes very

nearly through the center of percussion of the tanker, residual motions

following impact are insignificant.

The test vehicle itself is a 7 ,700-gal Ion, 10-ga steel-shell tanker com- prising the full trailer of a typical Michigan double. The tank has

334
Figure 5. Test vehicle set up for severe rollover experiment.

three compartments, of capacities 3,550 gallons, 1,450 gallons, and

2,700 gallons, numbered 1, 2, 3, respectively, from left to right. For

the first experiment, the 1st and 3rd compartments were nominally filled

with water, leaving a three-percent ullage volume, or free space, in

both loaded compartments. This loading condition was chosen since it

yielded the design gross load of the vehicle, 65,000 lbs. The manhole

covers were all of the clamping-band type shown earlier. The manhole

cover in the filled #1 compartment was left in its as-designed state

while the #3 cover was mechanically blocked to prevent its dislodging.

Transducers were installed to record two fluid pressures adjacent to

the manhole in both the 1st and 3rd compartments, two acceleration signals normal to the impact point, and the instantaneous angular position

of the vehicle during its fall. Data were recorded on an FM tape re- corder, as well as on oscillographic pen-chart recorders.

Shown in Figure 6 is a photo of the tanker striking the pavement. In Figure 7 we see the "river" that was created within two minutes following the impact-dislodgement of the #1 manhole cover. Subsequent inspection showed that the bulkhead between compartments #2 and #3 had failed

in the vicinity of the impact deformation. Further, following completion of the second impact experiment using the same test vehicle, it was discovered that an artificial cushioning of the internal fluid pres- sures had taken place due to partial collapse of air tanks which existed inside each of the three compartments. The air tanks had been installed inside the compartments during a previous research study [2]

for purposes of displacing fluid so that a water load would yield the same inertial parameters as a reference loading of gasoline. Thus, the

fluid pressure data taken in experiments 1 and 2 were looked upon as

335
336
representing an unknown degree of underestimation of pressures actually

pertaining to such rollover impact situations. Nevertheless, the re- sults of these experiments do aid in obtaining an understanding of the

mechanisms contributing to internal pressure.

Shown in Figure 8 are the recorded time histories from pressure transducers and accelerometers installed on the vessel. From the top, we see the two pressure signals from compartment #1, next the two pressure

signals from compartment #3, and finally, the two acceleration signals

(which show signal Ai limiting at 20 g's while the broader range accelerometer, signal A2, continues to yield a measurement). The pressures

in compartment #3 pertain to a condition in which the manhole cover is

blocked to prevent dislodgement. The pressures in compartment #1, on the other hand, provide a measure of the pressure causing one specific

manhole cover to dislodge. Although we see variations in the noise

content of the four pressure signals, the nominal response entails a low frequency (~ 10 Hz) peak in the range of 20 to 25 psi and high frequency (> 100 Hz) spikes from 30 to 50 psi. Interestingly, the signals

obtained in the "blocked" compartment are virtually the same as those

obtained in the compartment in which the 20-inch diameter orifice was opened, upon having dislodged the manhole cover. This result was initially surprising since it had been expected that failure of a manhole

cover would act to relieve the pressures experienced in the involved

compartment. The observation can be explained, however, on the basis of

the very limited time period over which peak pressures are sustained,

as contrasted with the time needed to accelerate a sufficient quantity

of fluid out of the manhole opening to provide a pressure-relieving

effect.

The accelerometer signal, A2, provides a continuous recording of accelerations normal to the ground plane, showing a noisy, and relatively

low-level, response for the first 30 milliseconds, followed by a rather

sustained pulse of approximately 25 g's amplitude. Double integration

of the A2 signal, by graphical means, yields a net deflection of the

tank wall which agrees well with the nominal 8-inch maximum deformation

measured on the vessel.

Experiments #2 Through #4 - The subsequent rollover tests were of the

simple "tipover" variety by which the tanker was brought just beyond

the point of unstable equilibrium by means of a laterally-affixed tow

cable, and then tipped over to strike the ground at a 90° roll angle.

Again, all manhole covers but one were mechanically blocked to prevent

dislodgement. In each case, the nominal result of the test was as depicted in Figures 9 and 10. Namely, the rollover impact caused an extensive spray of fluid from the low-pressure vents on each manhole

cover while the "unblocked" manhole cover, at the right in these

figures, was dislodged.

337
in

1

.o±0 ^ecoo:

3>!

'3s /fp

36-

^ ''li, '

Figure 8. Impact response data gathered in severe rollover experiment

338
Figure 9. Fluid spraying through low pressure vents at impact, while

large plume at right derives from dislodgement of manhole

cover.

Figure 10. Leaking low pressure vents at left, manhole cover

dislodged at right.

339
In the last two of the tipover experiments, a more extensive set of

pressure measurements were made inside the vessel and the initial ullage

or vacant volumes were made equal to 10 percent and 3 percent, respectively, of the total volume in each compartment. An increase in the

ullage space (to 10 percent) was of interest since examination of the

tank deformations resulting from the previous (3 percent ullage) tests

showed that the volume displaced through crushing of the tank was approaching 3 percent of the tank volume. Thus a substantial fraction of

the peak level of internal pressure would appear to have derived from

simple compression of the air space inside the vessel. According to

the Ideal Gas Law, of course, one would expect that fluid pressure

levels would reduce if the initial ullage space is increased and if the

"crushed volume" remains constant. The results illustrate that, while

this hypothesis is qualitatively correct, the numbers indicate that internal pressure is actually determined from a fairly complex set of

mechanisms. Data from the tipover test run with 10 percent ullage volume show a low frequency peak pressure of 21 psi, while the corresponding test with 3 percent ullage produced a low frequency measure of peak

pressure equal to 27 psi. Pressure spikes reached an average of 41 psi

for the 10 percent ullage case, and 54 psi for the 3 percent ullage

case. Accordingly, for this simple index in ullage volume, it is clear

that compression of the trapped air is a significant mechanism con- tributing to the internal pressure which causes dislodgement of manhole covers.

The second primary mechanism involves the pressure gradient induced by

acceleration of the bulk fluid mass. It can be shown that the pressure

value, p, experienced at any point which is h (ft) below the surface of

a liquid of density, p, (Ib/ft^) whose total bulk volume is subject to

a normal acceleration having amplitude An (g's) is given by:

A h P = P W" ^P^^"^

For the nominal average values of acceleration experienced during the

rollover impacts (approximately 6 to 10 g's), average pressure levels

equal to approximately 10 to 16 psi at the center of the manhole will

derive from the "bulk acceleration" mechanism. Higher levels of shortlived pressure pulses presumably result from the nonuniform acceleration condition and from acoustic, or shock, phenomena within the fluid.

Another mechanism contributing to fluid pressures at the manhole derives from the horizontal component of the impact acceleration vector.

This component is produced when the tank strikes the ground because

there exists a horizontal component of velocity which becomes reduced

toward zero upon generation of frictional forces between the tank shell

and the pavement. The horizontal acceleration level can approach or even exceed 1 g since high normal forces are created by the high normal

acceleration levels such as were illustrated in Figure 8. Over the

length of the water column measuring 8 feet along the original vertical

axis of the tank section which was tested, for example, a 10-g normal

340
acceleration at impact will produce a 1-g horizontal acceleration and a 3.5 psi additional pressure increment at the manhole cover, presuming a 0.1 frictional coupling between shell steel and pavement.

Conclusions Drawn from the Rollover Experiment: Insofar as the fluid

employed in the foregoing tests was water, whose density is 8.3 lb/gal

compared to 6.1 lb/gal for gasoline, the test measurements of the impact

pressure applied to manhole covers are somewhat conservative, that is,

somewhat higher than would derive if the load had been gasoline. Given

that more than one mechanism contributes to impact pressures applied to

manhole covers, however, the degree of conservatism cannot be easily

determined. For example, if the only mechanisms giving rise to internal

pressure, at impact, were those associated with bulk acceleration of the

fluid mass, the pressures to be expected from the same volume of gasoline would be equal to the ratio of the fluid densities of gasoline

versus water times the pressure level measured using water as the test

fluid (viz., gasoline pressure = (6.1/8.3), or 74 percent of the water

pressure level). In actual impacts, however, the gasoline pressure

would be higher than the indicated 74 percent of water pressure levels

since, clearly, the compression of the ullage space due to tank deformation constitutes a major mechanism for generation of internal pressure

at impact. Obviously, the ullage space compression mechanism is insensitive to the density of the liquid product.

Accordingly, it was concluded that the measured pressure levels provide a reasonable, and somewhat conservative, estimate of impact pressures bearing upon manhole covers in the rollover of actual gasolinetransporting tankers of the type examined. The worst condition

expected for simple tipover onto a rigid pavement entails, approximately, a 27-psi pressure pulse lasting on the order of 50 milliseconds, with 2-millisecond pulses reaching as high as 60 psi. On the

strength of these findings, recommendations for improved gasoline

tankers in the State of Michigan included a specification of 50 psi as the steady-state pressure containment capability of manhole covers.

References

1. Ervin, R.D., et al . "Future Configuration of Tank Vehicles Hauling

Flammable Liquids in Michigan." Final Report, Agreement #78-2230,

Highway Safety Research Institute, University of Michigan, Report

No. UM-HSRI-80-73, December 1980.

2. Ervin, R.D., et al . "Ad Hoc Study of Certain Safety-Related Aspects

of Double-Bottom Tankers." Final Report, Contract No. MPA-78-002A,

Highway Safety Research Institute, University of Michigan, Report

No. UM-HSRI-78-18, May 7, 1978.

341

APPENDIX

MECHANICAL FAILURES PREVENTION GROUP

DAMAGE PREVENTION IN THE TRANSPORTATION ENVIRONMENT

34th Meeting

October 21-23, 1981

Attendance List

Mike T. Bohlman

Sea-Land Service, Inc.

P.O. Box 1050

Elizabeth, NJ 07207

Marcia A. Boynton

USA MERADCOM, Rails Group

Mech. Equip. Branch, M & CE Lab.

ATTN: DRDME-HMM

Fort Bel voir, VA 22060

Edmund J. Cantilli

Dept. of Transportation Planning

& Engineering

Polytechnic Inst, of New York

New York, NY 11201

J. Chen

Advanced Tech. & Research, Inc.

12213 Cedar Hill Drive

Silver Spring, MD 20904

Bruce W. Christ

National Bureau of Standards

325 S. Broadway

Boulder, CO 80303

J. David Cogdell

Caterpillar Tractor Co.

100 NE Adams Street

Peoria, IL 61629

John P. Colletti

John P. Colletti & Assoc., Inc.

Box 1 3378

Pittsburgh, PA 15243

David Dancer

Federal Railroad Administration

3256 Hollyberry Court

Falls Church, VA 22042

William E. Dempsey

Transit Surveys, Inc.

100 Broadway

Massapequa, NY 11758

W. J. Downing

Southwest Research Inst.

P.O. Drawer 28510

6220 Culebra Road

San Antonio, TX 78284

James G. Early

National Bureau of Standards

Bldg. 223, Room A113

Washington, DC 20234

Eugene L. Emerson

Sandia National Laboratories

P.O. Box 5800

Albuquerque, NM 87185

Henry English

Insurance Company of North America

1600 Arch Street

Philadelphia, PA 19101

Francois Envent

ManTech International Corp.

2320 Mill Road

Alexandria, VA 22314

345
Robert Ervin

Highway Safety Research Inst.

The University of Michigan

Ann Arbor, MI 48109

Gary R. Forton

Fruehauf Corp.

6500 French Road

Detroit, MI 48213

William D. Gods hall

Forest Products Laboratory

USDA, Forest Service

P.O. Box 5130

Madison, WI 53705

Arnold Gross

Federal Railroad Administration

9101 Orchard Brook Drive

Potomac, MD 20854

Henry Hahn

Artech Corp.

2901 Telestar Court

Falls Church, VA 22042

Robert R. Hoi den

Hughes Aircraft Company

Bldg. Al, Mail Sta. 3C923

P.O. Box 9399

Long Beach, CA 90810-0399

Lester Johnson

TWA

2506 Linden Drive

Kansas City, KS 66106

Brad Johnstone

Pullman Standard

1414 Field Street

Hammond, IN 46320

George Kachadourian

The Mitre Corp,

1820 Dolley Madison Blvd.

McLean, VA 22102

Pete Kiliani

Con Rail

1528 Walnut Street

Philadelphia, PA 19102

Elmer E. Klaus

133 Chemical Engineering Bldg.

The Pennsylvania State University

University Park, PA 16802

Gene H. Lamoreaux

Sandia National Laboratories

P.O. Box 5800

Albuquerque, NM 87185

Samuel R. Low, III

Bldg. 223, Room All 3

National Bureau of Standards

Washington, DC 20234

W. P. Manos

Association of American Railroads

3140 S. Federal Street

Chicago, IL 60616

R. A. May

Sandia National Laboratories

P.O. Box 5800

Albuquerque, NM 87185

B. M. McCarthy

The Asphalt Institute

6200 Montrose Road

Rockville, MD 20854

William G. Meeker

National Transportation Safety Bd.

800 Independence Avenue, SW

Washington, DC 20590

John Mirabel la

Federal Railroad Administration

400 Seventh Street, SW

Washington, DC 20590

Raymond F. Misialek

NAVSSES-052

Philadelphia, PA 19112

Robert Mumper

Trident Engineering Assoc.

48 Maryland Avenue

Annapolis , MD 21403

346
Claire Orth

Federal Railroad Administration

400 Seventh Street, SW

Washington, DC 20590

L. U. Pau

Battelle

5 Chemin Tressy-Cordy

CH 1212 Grand Lancy - Geneva

Switzerland

Marshall Peterson

Wear Sciences, Inc.

925 Mallard Circle

Arnold, MD 21012

Earl Phillips

Union Tank Car Co.

151st and Railroad Avenue

East Chicago, IN 46312

Ronald B. Pope

Sandia National Laboratories

P.O. Box 5800

Albuquerque, NM 87185

Joe B. Raidt

Association of American Railroads

3140 S. Federal Street

Chicago, IL 60616

R. V. Ramachadran

Wyle Laboratories

4620 Edison

Colorado Springs, CO 80915

R. T. Reese

Sandia National Laboratories

P.O. Box 5800

Albuquerque, NM 87185

John J. Richardson, Jr.

Naval Surface Weapons Center

White Oak Laboratory

Silver Spring, MD 20910

Vern Romesberg

Sandia National Laboratory

P.O. Box 5800

Albuquerque, NM 87185

William Ruff

National Bureau of Standards

Bldg. 223, Room B266

Washington, DC 20234

J. C. Shang

GARD, Inc./GATX Corp.

7449 N. Natchez

Niles, IL 60648

T. Robert Shives

National Bureau of Standards

Bldg. 223, Room All 3

Washington, DC 20234

Leonard C. Smith

National Bureau of Standards

Bldg. 223, Room All

3

Washington, DC 20234

W. Sneed

Association of American Railroads

3140 S. Federal Street

Chicago, IL 60616

Jesse E. Stern

Trident Engineering Assoc.

1507 Amherst Road

Hyattsville, MD 20783

Michael Thomas

Great Dane Trailers, Inc.

108 Manchester Road

Savannah, GA 31410

Henry Tobin

IIT Research Institute

10 W. 35th Street

Chicago, IL 60615

Bill Vesser

Tektroni x 14325 SW, Kimberly Drive

Beaverton, OR 97005

William A. Vickerman

Association of American Railroads

59 E. Van Buren Street

Chicago, IL 60605

347
G. Allan Whittaker

Honeywel 1 , Inc

.

P.O. Box 524

Minneapolis, MN 55440

Bryan D. Winn

Southwest Research Institute

P.O. Drawer 28510

6220 Culebra Road

San Antonio, TX 78284

Peter J. Wong

SRI International

333 Ravenswood Avenue

Menlo Park, CA 94025

Jackson Yang

University of Maryland

Mechanical Engineering Dept.

College Park, MD 20742

Richard Yoshimura

Sandia National Laboratories

P.O. Box 5800

Albuquerque, NM 87185
MFPG PUBLICATIONS

Both printed and microfiche copies of the following MFPG publications

(1-12) whose catalog numbers start with either "AD" or "COM" may be

obtained from the NTIS.

National Technical Information Service

5285 Port Royal Road

Springfield, VA 22151

1. Glossary of Terms AD 721 354

2. Proceedings of Meeting Nos . 1-9 (set of 5) AD 721 359

Meeting Nos. 1-5 Papers and discussion on failure

analysis and control

"Detection, Diagnosis and Prognosis"

December 6, 1968

"Failure Mechanisms as Identified

with Helicopter Transmissions"

March 27, 1969

"Critical Failure Problem Areas in

the Aircraft Gas Turbine Engine"

June 25-26, 1969

"Potential for Reduction of Mechanical

Failure through Design Methodology"

November 5-6, 1969

3. Proceedings of Meeting No. 10 AD 721 912

"Vibration Analysis Systems"

January 21-22, 1970

4. Proceedings of Meeting No. 11 AD 724 475

"Failure Mechanisms: Fatigue"

April 7-8, 1970

5. Proceedings of Meeting No. 12 AD 721 913

"Identification and Prevention of Mechanical

Failures in Internal Combustion Engines"

July 8-9, 1970

Meeting No. 6

Meeting No. 7

Meeting No. 8

Meeting No. 9

349
6. Proceedings of Meeting No. 13 AD 724 637

"Standards as a Design Tool in Surface

Specification for Mechanical Components

and Structures"

October 19-20, 1970

7. Proceedings of Meeting No. 14 AD 721 355

"Advances in Decision-Making Processes

in Detection, Diagnosis and Prognosis"

January 25-26, 1971

8. Proceedings of Meeting No. 15 AD 725 200

"Failure Mechanisms: Corrosion"

April 14-15, 1971

9. Proceedings of Meeting No. 16 AD 738 855

"Mechanical Failure Prevention through

Lubricating Oil Analysis"

November 2-4, 1971

10. Proceedings of Meeting No. 17 AD 750 411

"Effects of Environment upon Mechanical

Failures, Mechanisms and Detection"

April 25-27, 1972

11. Proceedings of Meeting No. 18 AD 772 082

"Detection, Diagnosis and Prognosis"

November 8-10, 1972

12. Proceedings of Meeting No. 19 (NBS SP 394) COM-74-50523

"The Role of Cavitation in Mechanical

Failures"

October 31 -November 2, 1973

Printed copies of the following MFPG publications (catalog numbers

starting with SN) may be obtained from the U. S. Government Printing

Offi ce

.

Superintendent of Documents

U. S. Government Printing Office

Washington, DC 20402

Microfiche copies of these publications (catalog numbers starting with

NBS SP) may be obtained from NTIS.

13. Proceedings of Meeting No. 20 (NBS SP 423) . . . SN003-003-01451 -6

"Mechanical Failure - Definition of

the Problem"

May 8-10, 1974

Cost, Printed Copy: $6.10

350
14. Proceedings of Meeting No. 21 (NBS SP 433) . . . SN003-003-01 639-0

"Success by Design: Progress through

Failure Analysis"

November 7-8, 1974

Cost, Printed Copy: $3.50

Microfiche Copy: $2.25

15. Proceedings of Meeting No. 22 (NBS SP 436) . . . SN003-003-01 556-3

"Detection, Diagnosis and Prognosis"

April 23-25, 1975

Cost, Printed Copy: $4.25

Microfiche Copy: $2.25

16. Proceedings of Meeting No. 23 (NBS SP 452) . . . SN003-003-01 664-1

"The Role of Coatings in the Prevention

of MecKanical Failures"

October 29-31 , 1975

Cost, Printed Copy: $2.65

17. Proceedings of Meeting No. 24 (NBS SP 468) . . . SN003-003-01 760-4

"Prevention of Failures in Coal

Conversion Systems"

April 21-24, 1976

Cost. Printed Copy: $3.00

18. Proceedings of Meeting No. 25 (NBS SP 487) . . . SN003-003-01 829-5

"Engineering Design"

November 3-5, 1976

Cost, Printed Copy: $5.25

19. Proceedings of Meeting No. 26 (NBS SP 494) . . . SN003-003-01 844-9

"Detection, Diagnosis and Prognosis"

May 17-19, 1977

Cost, Printed Copy: $4.50

20. Proceedings of Meeting No. 27 (NBS SP 514) . . . SN003-003-01 935-6

"Product Durability and Life"

November 1-3, 1977

Cost, Printed Copy: $3.75

21. Proceedings of Meeting No. 28 (NBS SP 547) . . . SN003-003-02083-4

"Detection, Diagnosis and Prognosis"

November 28-30, 1978

Cost, Printed Copy: $7.00

22. Proceedings of Meeting No. 29 (NBS SP 563) . . . SN003-003-02120-2

"Advanced Composites: Design and Applications"

May 23-25, 1979

Cost, Printed Copy: $7.00

351
23. Proceedings of Meeting No. 30 (NBS SP 584) . . . SN003-003-02272-1

"Joint Conference on Measurements and

Standards for Recycled Oil /Systems

Performance and Durability"

October 23-26, 1979

Cost, Printed Copy: $8.00

24. Proceedings of Meeting No. 31 (NBS SP 621 ) ... SN003-003-02428-7

"Failure Prevention in Ground

Transportation Systems"

April 22-24, 1980

Cost, Printed Copy: $7.50

25. Proceedings of Meeting No. 32 (NBS SP 622) . . . SN003-003-02361 -2

"Detection, Diagnosis and Prognosis:

Contribution to the Energy Challenge"

October 7-9, 1980

Cost, Printed Copy: $8.00

26. Proceedings of Meeting No. 33 (NBS SP 640) . . . SN003-003-02425-2

"Innovation for Maintenance

Technology Improvements"

April 21-23, 1981

Cost, Printed Copy. $11.00

352
NBS-n4A iREv. 2-6CI U.S. DEPT. OF C OMM. 1. PUBLICATION OR 2, Performinj Or^an. Report No. 3. Publication Date BIBLIOGRAPHIC DATA

REPORT NO.

SHEET (See instructions) April 1983 NBS SP 652

4. TITLE AND SUBTITLE

Damage Prevention in the Transportation Environment

Proceedings of the 34th Meeting of the Mechanical Failures Prevention Group held at

NBS, Gaithersburg, MD, October 21-23, 1981

5. AUTHOR(S)

T. Robert Shives, Editor

6. PERFORMING ORGANIZATION (If joint or other than NBS. see instructions) 7. Contract/Grant No. NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE 8. Type of Report & Period Covered

WASHINGTON, D.C. 20234

Final

9. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street, City, Stole, ZIP)

National Bureau of Standards, Washington, DC 20234

Office of Naval Research, U.S. Department of the Navy, Arlington, VA 22217

Naval Air Systems Command, U.S. Department of the Navy, Washington, DC 20360

NASA, Goddard Space Flight Center, Greenbelt, MD 20771

10. SUPPLEMENTARY NOTES

Library of Congress Catalog Card Nuomber: 83-600521

I

I Document describes a computer program; SF-185, FlPS Software Summary, is attached.

11. ABSTRACT (A 200-word or less factual summary of most si gnifi cant information. If document includes a si gnificant

bibliography or literature survey, mention it here)

These proceedings consist of 27 submitted entries (25 papers and 2 abstracts) from

the 34th Meeting of the Mechanical Failures Prevention Group which was held at the

National Bureau of Standards, Gaithersburg, Maryland, October 21-23, 1981. The

subject of the symposium was damage prevention in the transportation environment.

Areas of special emphasis included packaging for the transportation environment,

research in the railroad industry, damage prevention in the railroad industry,

designing for the transportation of hazardous materials, and highways.

12. KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by sernicolons)

Airline environment packaging; hazardous materials transportation; highway design;

marine environment packaging; packaging techniques; railroad environment packaging;

shipping; transportation; transportation damage prevention; trucking environment packa mg,

13. AVAILABILITY

PX] Unl imited [~| For Official Distribution. Do Not Release to NTIS

[X] Order From Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402.

Order From National Technical Information Service (NTIS), Springfield, VA, 22161

14. NO. OF

PRINTED PAGES

349

15. Price

$8.00

i; \JS. GOVERNMENT PRINTING OFFICE : 1983 O—380-997 (5023)



NBS TECHNICAL PUBLICATIONS

PERIODICALS

JOURNAL OF RESEARCH—The Journal of Research of the National Bureau of Standards reports NBS research and develop- ment in those disciplines of the physical and engineering sciences in which the Bureau is active. These include physics, chemistry,

engineering, mathematics, and computer sciences. Papers cover a broad range of subjects, with major emphasis on measurement

methodology and the basic technology underlying standardization. Also included from time to lime are survey articles on topics

closely related to the Bureau's technical and scientific programs. As a special service to subscribers each issue contains complete

citations to all recent Bureau publications in both NBS and non- NBS media. Issued six times a year. Annual subscription: domestic

$18; foreign $22.50. Single copy, $5.50 domestic; $6.90 foreign.

NONPERIODICALS

Monographs—Major contributions to the technical literature on

various subjects related to the Bureau's scientific and technical activities. Handbooks—Recommended codes of engineering and industrial practice (including safety codes) developed in cooperation with in- terested industries, professional organizations, and regulatory

bodies. Special Publications—Include proceedings of conferences sponsored by NBS, NBS annual reports, and other special publications

appropriate to this grouping such as wall charts, pocket cards, and

bibliographies. Applied Mathematics Series—Mathematical tables, manuals, and

studies of special interest to physicists, engineers, chemists,

biologists, mathematicians, computer programmers, and others engaged in scientific and technical work.

National Standard Reference Data Series— Provides quantitative data on the physical and chemical properties of materials, compiled from the world's literature and critically evaluated. Developed under a worldwide program coordinated by NBS under

the authority of the National Standard Data Act (Public Law

90-396).

NOTE: The principal publication outlet for the foregoing data is the Journal of Physical and Chemical Reference Data (JPCRD)

published quarterly for NBS by the American Chemical Society

(ACS) and the American Institute of Physics (AIP). Subscriptions,

reprints, and supplements available from ACS, 1 155 Sixteenth St., NW, Washington, DC 20056.

Building Science Series—Disseminates technical irformation developed at the Bureau on building materials, components,

systems, and whole structures. The .series presents research results,

test methods, and performance criteria related to the structural and

environmental functions and the durability and safety characteristics of building elements and systems.

Technical Notes—Studies or reports which are complete in themselves but restrictive in their treatment of a subject. Analogous to monographs but not so comprehensive in scope or definitive in treatment of the subject area. Often serve as a vehicle for final reports of work performed at NBS under the sponsorship of other government agencies.

Voluntary Product Standards—Developed under procedures

published by the Department of Commerce in Part 10, Title 15, of

the Code of Federal Regulations. The standards establish nationally recognized requirements for products, and provide all concerned interests with a basis for common understanding of the

characteristics of the products. NBS administers this program as a supplement to the activities of the private sector standardizing

organizations. Consumer Information Series—Practical information, based on NBS research and experience, covering areas of interest to the con- sumer. Easily understandable language and illustrations provide

useful background knowledge for shopping in today's tech- nological marketplace. Order the above NBS publications from: Superintendent oj Documents, Government Printing Office, Washington, DC 20402. Order the following NBS publications—FIPS and NBSIR's—from

the National Technical Information Service , Springfield, VA 22161

Federal Information Processing Standards Publications (FIPS

PUB)—Publications in this series collectively constitute the Federal Information Processing Standards Register. The Register

serves as the official source of information in the Federal Govern- ment regarding standards issued by NBS pursuant to the Federal Property and Administrative Services Act of 1949 as amended.

Public Law 89-306 (79 Stat. 1127), and as implemented by Executive Order 11717(38 FR 12315, dated May II, I973)and Parl6

of Title 15 CFR (Code of Federal Regulations).

NBS Interagency Reports (NBSIR)—A special series of interim or

final reports on work performed by NBS for outside sponsors

(both government and non-government). In general, initial dis- tribution is handled by the sponsor; public distribution is by the National Technical Information Service , Springfield, VA 22161.

in paper copy or microfiche form.
U.S. Department of Commerce

National Bureau of Standards

Washington, D.C. 20234

Official Business

Penalty for Private Use $300

POSTAGE AND FEES PAID

U S. DEPARTMENT OF COMMERCE

COM-215

SPECIAL FOURTH-CLASS RATE BOOK