U.S. Department

of Transportation

Federal Railroad

Administration

Technical Criteria and Procedures for Evaluating 

the Crashworthiness and Occupant Protection 

Performance of Alternatively Designed Passenger 

Rail Equipment for Use in Tier I Service

Office of Railroad 

Policy and Development

Office of Safety

Washington, DC 20005

DRAFT

DOT/FRA/ORD-11/22 Final Report

October 2011
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October 2011 Technical Report

4. TITLE AND SUBTITLE 5. FUNDING NUMBERS

Technical Criteria and Procedures for Evaluating the Crashworthiness 

and Occupant Protection Performance of Alternatively Designed 

Passenger Rail Equipment for Use in Tier I Service

6. AUTHOR(S)

Compiled by Michael Carolan, Karina Jacobsen, Patricia Llana, Kristine 

Severson, Benjamin Perlman, and David Tyrell

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION 

REPORT NUMBERS

U.S. Department of Transportation

Research and Innovative Technology Administration

John A. Volpe National Transportation Systems Center

55 Broadway

Cambridge, MA 02142-1093

U.S. Department of Transportation

Federal Railroad Administration

Office of Railroad Policy and Development

Office of Safety

1200 New Jersey Avenue, SE

Washington, DC 20590

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSORING/MONITORING AGENCY 

REPORT NUMBER

U.S. Department of Transportation

Federal Railroad Administration

Office of Railroad Policy and Development

1200 New Jersey Avenue, SE

Washington, DC 20590

DOT/FRA/ORD-11/22

11. SUPPLEMENTARY NOTES

Program Manager: Melissa Shurland

12a. DISTRIBUTION/AVAILABILITY STATEMENT 12b. DISTRIBUTION CODE

This document is available to the public on the FRA Web site at 

http://www.fra.dot.gov.

13. ABSTRACT

Criteria and procedures have been developed for assessing crashworthiness and occupant protection performance 

of alternatively designed trainsets to be used in Tier I (not exceeding 125 mph) passenger service. These criteria 

and procedures take advantage of the latest technology in rail equipment crashworthiness and include aspects that

are fundamentally different from current regulations, such as the scenario-based train-level requirements, which 

have no counterpart in FRA‘s current Tier I regulations. Numerical values of the pass/fail criteria have been 

selected to provide an equivalent level of crashworthiness as the current Tier I regulations. For example, while the 

occupied volume integrity requirements have been relaxed from the current regulations, the criteria for 

preservation of the occupied volume for a collision with a locomotive-led train have been added to compensate. In 

other cases, such as roof integrity, the existing regulations can be applied to alternative equipment.

14. SUBJECT TERMS 15. NUMBER OF PAGES

RSAC, crashworthiness, waiver application, Tier I, standards, passenger equipment 177

16. PRICE CODE

17. SECURITY 

CLASSIFICATION

18. SECURITY CLASSIFICATION 

OF THIS PAGE

19. SECURITY CLASSIFICATION 

OF ABSTRACT

20. LIMITATION OF 

ABSTRACT

Unclassified Unclassified Unclassified Unlimited

NSN 7540-01-280-5500 Standard Form 298 (Rec. 2-89)

Prescribed by ANSI/NISO Std. 239.18

298-102
ii

METRIC/ENGLISH CONVERSION FACTORS 

ENGLISH TO METRIC METRIC TO ENGLISH

LENGTH (APPROXIMATE) LENGTH (APPROXIMATE)

1 inch (in) = 2.5 centimeters (cm) 1 millimeter (mm) = 0.04 inch (in)

1 foot (ft) = 30 centimeters (cm) 1 centimeter (cm) = 0.4 inch (in)

1 yard (yd) = 0.9 meter (m) 1 meter (m) = 3.3 feet (ft)

1 mile (mi) = 1.6 kilometers (km) 1 meter (m) = 1.1 yards (yd)

1 kilometer (km) = 0.6 mile (mi)

AREA (APPROXIMATE) AREA (APPROXIMATE)

1 square inch (sq in, in2) = 6.5 square centimeters (cm2) 1 square centimeter (cm2) = 0.16 square inch (sq in, in2)

1 square foot (sq ft, ft2) = 0.09 square meter (m2) 1 square meter (m2) = 1.2 square yards (sq yd, yd2)

1 square yard (sq yd, yd2) = 0.8 square meter (m2) 1 square kilometer (km2) = 0.4 square mile (sq mi, mi2)

1 square mile (sq mi, mi2) = 2.6 square kilometers (km2) 10,000 square meters (m2) = 1 hectare (ha) = 2.5 acres

1 acre = 0.4 hectare (he) = 4,000 square meters (m2)

MASS - WEIGHT (APPROXIMATE) MASS - WEIGHT (APPROXIMATE)

1 ounce (oz) = 28 grams (gm) 1 gram (gm) = 0.036 ounce (oz)

1 pound (lb) = 0.45 kilogram (kg) 1 kilogram (kg) = 2.2 pounds (lb)

1 short ton = 2,000 pounds 

(lb)

= 0.9 tonne (t) 1 tonne (t) =

=

1,000 kilograms (kg)

1.1 short tons

VOLUME (APPROXIMATE) VOLUME (APPROXIMATE)

1 teaspoon (tsp) = 5 milliliters (ml) 1 milliliter (ml) = 0.03 fluid ounce (fl oz)

1 tablespoon (tbsp) = 15 milliliters (ml) 1 liter (l) = 2.1 pints (pt)

1 fluid ounce (fl oz) = 30 milliliters (ml) 1 liter (l) = 1.06 quarts (qt)

1 cup (c) = 0.24 liter (l) 1 liter (l) = 0.26 gallon (gal)

1 pint (pt) = 0.47 liter (l)

1 quart (qt) = 0.96 liter (l)

1 gallon (gal) = 3.8 liters (l)

1 cubic foot (cu ft, ft3) = 0.03 cubic meter (m3) 1 cubic meter (m3) = 36 cubic feet (cu ft, ft3)

1 cubic yard (cu yd, yd3) = 0.76 cubic meter (m3) 1 cubic meter (m3) = 1.3 cubic yards (cu yd, yd3)

TEMPERATURE (EXACT) TEMPERATURE (EXACT)

[(x-32)(5/9)] F = y C [(9/5) y + 32] C = x F

QUICK INCH - CENTIMETER LENGTH CONVERSION

0 1 2 3 4 5

Inches

Centimeters 0 1 2 3 4 5 6 7 8 9 10 11 12 13

QUICK FAHRENHEIT - CELSIUS TEMPERATURE CONVERSION

 -40° -22° -4° 14° 32° 50° 68° 86° 104° 122° 140° 158° 176° 194° 212°

 

°F

 °C -40° -30° -20° -10° 0 ° 10° 20° 30° 40° 50° 60° 70° 80° 90° 100°

For more exact and or other conversion factors, see NIST Miscellaneous Publication 286, Units of Weights and Measures. 

Price $2.50 SD Catalog No. C13 10286 Updated 6/17/98
iii

Preface

Engineering Task Force Organization

The Engineering Task Force (ETF) reports to the Passenger Safety Working Group of the 

Railroad Safety Advisory Committee (RSAC).

Mission

The mission of the task force was to produce a set of technical criteria and procedures for 

evaluating passenger rail trainsets built to alternative designs. The technical evaluation criteria 

and procedures would provide a means of establishing whether equipment of an alternative 

design would result in at least equivalent performance to that of equipment designed in 

accordance with the structural standards in the Passenger Equipment Safety Standards (49 CFR 

Part 238). The criteria and procedures described in this document are specifically intended to 

apply to trainsets operated at speeds up to 125 mph that may need a waiver from (or, as 

appropriate under § 238.201(b), approval of alternative compliance with) one or more of the 

Passenger Equipment Safety Standards. The initial focus of this effort was on Tier I 

crashworthiness and occupant protection standards. This report is the product of this effort.

The criteria and procedures contained within this report provide a technical framework for 

presenting evidence to the Federal Railroad Administration (FRA) in support of a request for 

waiver of the Tier I crashworthiness and occupant protection standards, including the 

compressive (buff) strength requirements set forth in 49 CFR § 238.203. See, Rules of Practice 

(49 CFR Part 211) for rules on waiver petitions. In addition, these guidelines form a technical 

basis for making determinations concerning alternative compliance with the Tier I 

crashworthiness and occupant protection standards, as set forth in §238.201(b). The criteria and 

procedures contained in this report may be incorporated into the Passenger Equipment Safety 

Standards at a later date, after notice and opportunity for public comment.

Approach

In evaluating requests for waivers and other approvals for the use of passenger equipment not 

compliant with FRA‘s structural standards, FRA, with support from the John A. Volpe National 

Transportation Systems Center, has been reviewing and comparing the performance of domestic, 

conventional equipment with equipment designed to international standards. Based in part on 

knowledge gained from these reviews and similar evaluations conducted for more than a decade 

since Part 238 was promulgated, FRA presented a strawman technical proposal as a starting 

point for the task force. This initial strawman was heavily influenced by current state-of-the-art 

research results as well as established, international performance standards. The task force 

worked to modify each of the technical and the design verification requirements proposed in the 

strawman to better meet the goals outlined below.

Goals

The Task Force set out to meet the following goals:

 Use the collective ―best‖ thinking in the passenger rail industry;
iv

 Produce clear, realistic technical criteria and procedures for demonstrating equivalent 

performance; 

 Define the analysis and testing necessary to demonstrate the integrity of any specific 

design;

 Provide clear pass/fail analysis and testing criteria; and 

 Work expeditiously so that the technical criteria and procedures are available to sponsors 

of potential passenger rail service. 

The task force did not attempt to identify every possible means of determining the performance 

of alternative designs, and FRA did not anticipate that the availability of technical criteria and 

procedures would replace sound engineering judgment in reviewing requests for waivers and 

other approvals. However, it was anticipated that the availability of technical criteria and 

procedures could substantially reduce the uncertainty associated with demonstrating equivalent 

safety or alternative compliance.

Task Force Membership

Task force membership was open to designated representatives of RSAC member organizations 

participating in the Passenger Safety Working Group. FRA encouraged participation through one 

of those organizations by:

 Any car builder with capability to produce vehicles that will meet the proposed criteria, 

including those builders that can meet the current standards and any railroad or public 

authority that may procure new, alternatively designed equipment;

 Any consultant with extensive passenger rail car structural design experience; and

 Others who are valuable to the success of the Task Force, specifically including rail labor 

representatives.

The focus of this effort was the derivation of technical criteria suitable for determinations of 

equivalent safety with the existing standards. Accordingly, task force members were expected to 

continue to apply engineering principles neutrally and professionally.
v

Contents

Executive Summary..............................................................................................................................................1

1 Introduction...............................................................................................................................................3

1.1 Background...................................................................................................................... 3

1.2 Objective .......................................................................................................................... 4

1.3 Scope................................................................................................................................ 5

1.4 Overview of Development............................................................................................... 6

1.5 Document Organization................................................................................................... 6

1.1 1.6 Guidance Summary.................................................................................................... 8

2 Technical Basis.........................................................................................................................................9

2.1 Background...................................................................................................................... 9

2.2 Rail Equipment Crashworthiness Technology............................................................... 10

2.2.1 Occupied Volume Integrity ...................................................................................... 10

2.2.2 Crash Energy Management ..................................................................................... 12

2.2.3 Occupant Protection ................................................................................................ 15

2.3 Technical Basis for Criteria ........................................................................................... 22

2.3.1 Train-Level............................................................................................................... 25

2.3.2 Car-Level ................................................................................................................. 40

2.3.3 Interior Occupant Protection................................................................................... 46

3 Criteria ......................................................................................................................................................48

3.1 Requirement: Collision with Conventional Equipment................................................. 48

3.2 Requirement: Occupied Volume Integrity..................................................................... 50

3.3 Requirement: Colliding Equipment Override................................................................ 51

3.4 Requirement: Connected Equipment Override.............................................................. 52

3.5 Requirement: Fluid Entry Inhibition.............................................................................. 54

3.6 Requirement: End Structure Integrity of Cab End......................................................... 55

3.7 Requirement: End Structure Integrity of Noncab End................................................... 56

3.8 Requirement: Roof Integrity.......................................................................................... 57

3.9 Requirement: Side Structure Integrity ........................................................................... 58

3.10 Requirement: Truck Attachment.................................................................................... 59

3.11 Requirement: Interior Fixture Attachment..................................................................... 60

3.12 Requirement: Occupant Protection Features ................................................................. 61

4 Example Procedures ............................................................................................................................62

4.1 Introduction.................................................................................................................... 62

4.2 Guidance Summary........................................................................................................ 63

4.3 Requirement: Collision with Conventional Equipment................................................. 64

4.3.1 Criteria..................................................................................................................... 64

4.3.2 Example Procedures................................................................................................ 65

4.3.3 Example Key Results................................................................................................ 71

4.4 Requirement: Occupied Vehicle Integrity ..................................................................... 81

4.4.1 Criteria..................................................................................................................... 81
vi

4.4.2 Example Procedure.................................................................................................. 82

4.5 Requirement: Colliding Equipment Override................................................................ 89

4.5.1 Criteria..................................................................................................................... 89

4.5.2 Example Procedure.................................................................................................. 90

4.5.3 Example Key Results................................................................................................ 90

4.6 Requirement: Connected Equipment Override.............................................................. 92

4.6.1 Criteria..................................................................................................................... 92

4.6.2 Example Procedure.................................................................................................. 93

4.6.3 Example Key Results................................................................................................ 94

4.7 Requirement – End Structure Integrity of Cab End....................................................... 96

4.7.1 Criteria..................................................................................................................... 96

4.7.2 Example Procedures................................................................................................ 97

4.8 Requirement – End Structure Integrity of Noncab End............................................... 105

4.8.1 Criteria................................................................................................................... 105

4.8.2 Example Procedures.............................................................................................. 106

4.9 Requirement: Truck Attachment.................................................................................. 110

4.9.1 Criteria................................................................................................................... 110

4.9.2 Example Procedure................................................................................................ 110

4.9.3 Example Results..................................................................................................... 111

4.10 Summary and Next Steps............................................................................................. 113

5 References ..............................................................................................................................................114

Appendix A. Selected Train Incidents.......................................................................................................118

Appendix B. Selected CFR References.....................................................................................................127

Appendix C. Locomotive and Passenger Car Input Data .................................................................148

Appendix D. Railroad Safety Advisory Committee Passenger Safety Working Group 

Engineering Task Force....................................................................................................................158

Definitions.............................................................................................................................................................163

Abbreviations and Acronyms.......................................................................................................................164
vii

Illustrations

Figure 1. 800,000 lb on Line of Draft........................................................................................... 11

Figure 2. Schematic Illustration of Crush Zone Locations in Commuter Rail Passenger Train .. 12

Figure 3. Cab Car Crush Zone ...................................................................................................... 13

Figure 4. Frames from High-Speed Movies of Conventional (top) and CEM (bottom) 

Train-to-Train Tests....................................................................................................... 14

Figure 5. Example of Uncontrolled Car-to-Car Interactions........................................................ 14

Figure 6. Examples of Controlled Car-to-Car Interactions........................................................... 15

Figure 7. Computer Simulation Illustrating Occupant Kinematics .............................................. 16

Figure 8. Representative SIV Plot Corresponding to Various Seating Configurations................ 17

Figure 9. Example SIV Plot with Injury Interpretation ................................................................ 18

Figure 10. Design of an Improved Workstation Table ................................................................. 19

Figure 11. Pre- and Posttest Photos of Table Test........................................................................ 20

Figure 12. Schematic of Prototype Commuter Seat...................................................................... 21

Figure 13. Pre- and Posttest Photos of Forward-Facing 8g Sled Test .......................................... 22

Figure 14. Pre- and Posttest Photos of Rear-Facing 12g Sled Test .............................................. 22

Figure 15. Schematic of Collision Scenario ................................................................................. 25

Figure 16. Aerial Photograph of Placentia Accident [27]............................................................. 26

Figure 17. Estimated Force-Crush Characteristics for Tier I-Compliant (blue) and 

EN-Compliant (red) Equipment.................................................................................. 27

Figure 18. Distribution of Crush in the EN-Compliant Train in Prescribed Scenario, Closing 

Speeds of 15 and 20 mph ............................................................................................ 28

Figure 19. SIV Plot for EN-Compliant Equipment ...................................................................... 28

Figure 20. Illustration of Offset Conditions for Colliding Equipment ......................................... 29

Figure 21. Location of Offsets in Moving Consist: First Connected Interface ............................ 30

Figure 22. Illustration of Offsets for Coupled Cars...................................................................... 30

Figure 23. Illustration of Offsets for Articulated Cars.................................................................. 30

Figure 24. Cab Car Interaction with Conventional Locomotive in a Collision ............................ 31

Figure 25. CEM Cab Car Interaction with Conventional Locomotive in a Collision .................. 32

Figure 26. Non-CEM-Connected Equipment Interaction in a Collision ...................................... 33

Figure 27. CEM Connected Equipment Interaction in a Collision............................................... 34

Figure 28. Illustration of Principal Sources of Vertical Offset between Cars.............................. 35

Figure 29. Illustration of Principal Sources of Lateral Offset between Cars................................ 35
viii

Figure 30. Accident Conditions in Which Trucks Have Remained Attached .............................. 37

Figure 31. Accident Conditions in Which Trucks Have Become Detached................................. 37

Figure 32. Illustration of the Influence of Longitudinal Suspension on 

Suspension Stop Loading............................................................................................ 38

Figure 33. Example Load-Displacement Characteristic Indicating Crippling Load .................... 41

Figure 34. Lead Cab Car after Striking Truck at Highway-Rail Grade Crossing 

(Portage, IN – 1998) ................................................................................................... 42

Figure 35. Corner and Side Damage to Trailing Coach (Gary, IN – 1997).................................. 43

Figure 36. MU Side Structure Damage after Striking Construction Equipment 

(Hewlett, NY – 2001) ................................................................................................. 44

Figure 37. Derailed Car Supported by its Roof and Side Structures (Nodaway, IA – 2001)....... 45

Figure 38. Collision Scenario ....................................................................................................... 48

Figure 39. Engineer‘s Seat with Survival Space Indicated........................................................... 49

Figure 40. Location of Offsets in Moving Consist ....................................................................... 52

Figure 41. Illustration of Offsets for Coupled Cars...................................................................... 52

Figure 42. Illustration of Offsets for Articulated Cars.................................................................. 53

Figure 43. Collision Scenario ....................................................................................................... 64

Figure 44. Engineer‘s Seat with Survival Space Indicated........................................................... 65

Figure 45. Flowchart of Evaluation Procedure ............................................................................. 66

Figure 46. Relationship between Car/Locomotive Crush Evaluation and Train Collision 

Dynamics Evaluation .................................................................................................. 67

Figure 47. Key Inputs and Outputs for Car Crush Analysis......................................................... 68

Figure 48. Key Inputs and Outputs for Collision Dynamics Evaluation ...................................... 68

Figure 49. Schematic of a Lumped-Parameter Model for a Train-to-Train Collision Scenario... 69

Figure 50. Schematic of a Finite Element Model for a Train-to-Train Collision Scenario .......... 69

Figure 51. Example Idealized Force-Crush Characteristics ......................................................... 71

Figure 52. Verification of Force-Crush Characteristic through a Series of Full-Scale 

Structural Component Tests........................................................................................ 73

Figure 53. Rigid and Deformable Geometry of an F40PHM-Based Locomotive........................ 74

Figure 54. Cab-End Model of FRA-Prototype CEM Cab Car...................................................... 74

Figure 55. Cab Car Ideal Dynamic Crush Analysis...................................................................... 75

Figure 56. Example Kinematic Sequence of Events from Car-Level Crush Analysis................. 76

Figure 57. Example Car-Level Crush Analysis Measured Force-Crush Characteristic ............... 77

Figure 58. Flowchart Showing Procedure for Calculating Intrusion into Occupied Volume ...... 78
ix

Figure 59. Example Crush Results from One-Dimensional Lumped Mass Model: Crush 

Distribution for Each Car End in the Consist ............................................................. 79

Figure 60. Flowchart Showing Procedure for Calculating SIV Estimates ................................... 80

Figure 61. Relative Displacement and Relative Velocity Plots for Moving Consist.................... 80

Figure 62. Example SIV Characteristics....................................................................................... 81

Figure 63. Example of Load-Displacement Characteristic Indicating Crippling ......................... 82

Figure 64. Example Load-Displacement Characteristics at Front and Back End 

with 5 Percent Envelope ............................................................................................. 84

Figure 65. Example Ratio of Kinetic Energy to Strain Energy for Analysis................................ 85

Figure 66. Example Load-Displacement Characteristic Showing Crippling Load 

Exceeds 1,200,000 lb .................................................................................................. 88

Figure 67. Dynamic Crush Analysis with Lateral and Vertical Offsets ....................................... 90

Figure 68. Displacement Results from Dynamic Crush Analysis: Ideal Impact Conditions........ 91

Figure 69. Displacement Results from Dynamic Crush Analysis: Offset Impact Conditions...... 91

Figure 70. Location of Offsets in Moving Consist ....................................................................... 92

Figure 71. Illustration of Offset for Coupled Cars........................................................................ 92

Figure 72. Illustration of Offset for Articulated Cars................................................................... 93

Figure 73. Dynamic Crush Analysis: Ideal Impact Conditions (Courtesy of Alstom)................. 93

Figure 74. Deformation in Coupled Car Dynamic Crush Analysis: Ideal Impact Conditions 

(Courtesy of Alstom) .................................................................................................. 94

Figure 75. Relative Vertical Displacement of the Underframes of Two Coupled Cars 

(Courtesy of Alstom) .................................................................................................. 94

Figure 76. Vertical Displacement of Four Wheels (Courtesy Alstom) ........................................ 95

Figure 77. Still Photographs from High-Speed Video, Collision Post Test ................................. 98

Figure 78. Contours of Equivalent Plastic Strain for the Quasi-Static Collision 

Post Load Case............................................................................................................ 99

Figure 79. Contours of Equivalent Plastic Strain for the Quasi-Static Corner Post Load Case ... 99

Figure 80. Test Component Approximation for Component Test.............................................. 100

Figure 81. Example Analysis Results of Car with Deformable Energy Absorbers.................... 102

Figure 82. Example of a Dynamic Drop Tower Test of a CEM Component ............................. 103

Figure 83. Example of a Quasi-Static Test of a CEM Component............................................. 103

Figure 84. Side View of Car Showing 150-Kilopound Load ..................................................... 106

Figure 85. Side View of Car Showing 20-Kilopound Load ....................................................... 107

Figure 86. Side View of Car Showing 30-Kilopound Load ....................................................... 108
x

Figure 87. Finite Element Model Showing Side Structure Load and Boundary Conditions...... 109

Figure 88. Cab Car Deceleration-Time History (Courtesy of Alstom) ...................................... 111

Figure 89. Cab Car Lead Truck Deceleration-time History (Courtesy of Alstom) .................... 112
xi

Tables

Table 1. Guidance Summary for Criteria and Evaluation.............................................................. 8

Table 2. Summary of CFR Requirements and Criteria for Truck Attachment............................ 39

Table 3. Guidance Summary for Criteria and Evaluation............................................................ 63

Table 4. Example of Key Inputs for Collision Dynamics Analysis............................................. 70

Table 5. Example Matrix of Component Testing and Analysis................................................... 72

Table 6. Example Matrix of Component Testing and Analyses................................................ 104
1

Executive Summary

The passenger rail industry is on the cusp of tremendous growth due, in part, to the increasing 

effects of congestion on highway systems, carbon emission concerns, and the price of gasoline. 

A recent U.S. Department of Transportation study suggests the potential for up to 100 new rail 

authorities in the next 20 years, depending on available State and Federal funding. With the 

proliferation of planned passenger rail systems around the country, more States and operating 

authorities desire to use passenger equipment designed to meet alternative standards, which have 

been proven in foreign operating conditions but not under the more stringent regulations in the 

United States.

The Federal Railroad Administration‘s (FRA) primary mission is to provide for the safety of the 

Nation‘s railroads by administering the railroad safety laws and regulations. Railroads and 

operating authorities can petition FRA to waive regulations, including the crashworthiness 

regulations that apply to rail passenger equipment. Each petition for waiver is expected to 

contain sufficient information to support the action sought, including an evaluation of anticipated 

impacts. To provide for safety while making best use of its resources and to facilitate passenger 

rail industry growth, FRA has decided to develop, in consultation with the rail industry, 

alternative criteria and procedures for assessing the crashworthiness of rail passenger trainsets

that are applicable to a wide range of equipment designs. These criteria and procedures are 

intended to be used by the rail industry in developing information to support waiver petitions and 

by FRA in evaluating waiver petitions. The criteria and procedures described in this document 

are specifically intended to apply to trainsets operated at speeds up to 125 miles per hour (mph). 

The criteria and procedures may also be incorporated into the Passenger Equipment Safety 

Standards at a later date, after notice and opportunity for public comment.

Consultation with the industry was accomplished through the Engineering Task Force (ETF). 

This task force reports to the Passenger Safety Working Group of the Railroad Safety Advisory 

Committee (RSAC). The Task Force set out to meet the following goals:

 produce clear, realistic technical requirements, benefiting from the collective ―best‖ 

thinking in the passenger rail industry;

 define the analysis and testing required to demonstrate compliance with the technical 

requirements;

 provide clear pass/fail criteria for the analyses and tests; and

 work expeditiously so that sponsors of potential passenger service recognize available 

equipment options.

Task force membership was open to designated representatives of RSAC member organizations 

participating in the Passenger Safety Working Group. FRA encouraged participation through one 

of those organizations by:

 any railroad or public authority that may procure new equipment;

 any car builder with capability to produce vehicles for rail passenger service, including 

those builders that can meet the current standards;

 any consultant with extensive passenger rail car structural design experience; and
2

 others who are valuable to the success of the task force, specifically including rail labor 

representatives.

The objective of this effort was to develop criteria and procedures for assessing the 

crashworthiness and occupant protection performance of alternatively designed equipment to be 

used in Tier I service. Alternative designs include trainsets originally intended for operation 

outside the United States that may not be compliant with current FRA Tier I crashworthiness 

regulations. As defined in Part 238, Tier I service includes any passenger rail service operating at 

speeds up to 125 mph. Criteria are defined by the conditions that will be evaluated and the 

critical results from the evaluation. Procedures are defined as the analysis and test techniques 

applied to demonstrate compliance with the criteria. The criteria and procedures that have been 

developed take advantage of the latest technology in rail equipment crashworthiness.

The criteria and procedures include aspects that are fundamentally different from current 

regulations, such as the scenario-based train-level requirements. No such requirements exist in 

FRA‘s current Tier I regulations. Numerical values of the pass/fail criteria have been selected to 

provide an equivalent level of crashworthiness as the current Tier I regulations. For example, the 

occupied volume integrity (OVI) requirements have been relaxed from the current regulations,

and criteria for preservation of the occupied volume for a collision with a locomotive-led train 

have been added to compensate. In other cases, such as roof integrity, the existing regulations 

can be applied to alternative equipment. Examples of analysis and test procedures that have been 

used to evaluate the performance of equipment are included in this document.
3

1. Introduction

1.1 Background

The passenger rail industry is on the cusp of tremendous growth due, in part, to the increasing 

effects of congestion on highway systems, carbon emission concerns, and the price of gasoline.

A recent U.S. Department of Transportation study suggests the potential for up to 100 new rail 

authorities in the next 20 years, depending on available State and Federal funding. With the 

proliferation of planned passenger rail systems around the country, more States and operating 

authorities desire to use passenger equipment designed to meet alternative standards. These 

standards have been proven in foreign operating conditions but not under the more severe 

regulations in the United States.

In general, requests to FRA for use of alternative designs have been handled through the waiver 

process. When a waiver request is initially proffered, the entirety of the information needed to be 

evaluated under the waiver request, and the potential impact of the waiver determination on the 

planned operation can be difficult to foresee. The waiver process also increases the workload for 

FRA, since the details of each operation must be collected, studied, and reviewed prior to making 

a determination on each waiver petition. The crashworthiness aspects have often required the 

most effort to address, with FRA typically asking the petitioner for additional information to 

supplement its original submission.

Since the Passenger Equipment Safety Standards were issued in 1999, advances have been made 

in rail car construction and crashworthiness. For instance, Crash Energy Management (CEM) 

technology, a means of absorbing energy to reduce the severity of a collision, has matured 

around the world. Although it can be, and has been, overlaid on rail equipment designed to be 

compliant with FRA‘s structural standards (compliant designs, as used herein), it is more 

commonly available on equipment designed to meet alternative standards. Under FRA 

sponsorship, the John A. Volpe National Transportation Systems Center (Volpe Center) has 

completed significant research into the effectiveness of CEM technology.

Through that research program, methodologies for accurately evaluating the crashworthiness of 

rail equipment with a high level of confidence have been developed and refined. Additionally, 

sophisticated analysis techniques for evaluating car crush behavior, train collision dynamics, and 

occupant dynamic response have been developed through research. Test techniques for 

measuring structural impact response, including component and substructure testing, and for 

measuring occupant kinematics and the likelihood of injury have also been developed. The 

results of these studies can be applied to evaluate the crashworthiness of a wide range of 

equipment designs.

With the potential for tremendous growth of the passenger rail industry, the safety of the trainriding public and the crews who transport the public becomes an ever greater priority. FRA 

recognizes that safety regulations appropriate for a wider variety of passenger rail operations are 

necessary for the passenger rail industry to efficiently and safely grow. To provide for safety 

while making best use of its resources and to facilitate passenger rail industry growth, FRA has 

decided to develop, in consultation with the rail industry, alternative criteria and procedures for 
4

assessing the crashworthiness of rail passenger equipment, applicable to a wide range of 

equipment designs.

1.2 Objective

This research was conducted to develop criteria and procedures for assessing the crashworthiness 

and occupant protection performance of alternatively designed trainsets to be used in Tier I 

service. Alternative designs include trainsets originally intended for operation in foreign 

countries that may not be compliant with current FRA Tier I crashworthiness regulations. As 

defined in Part 238, Tier I service includes intercity passenger and commuter rail service 

operating at speeds up to 125 mph. FRA notes that as part of its High-Speed Passenger Rail 

Safety Strategy, FRA intends to utilize appropriate safety standards and apply system safety 

program techniques to enhance safety while meeting transportation objectives. The strategy is 

available on FRA‘s Web site at 

http://www.fra.dot.gov/downloads/safety/HSRSafetyStrategy110609.pdf. In implementing this 

safety strategy, FRA has retasked the ETF to develop recommendations for engineering 

standards related to the safe operation of high-speed rail equipment at speed up to 220 mph. This 

effort may separately lead to the development of such alternative criteria and procedures for 

assessing the crashworthiness and occupant protection performance of rail passenger equipment 

intended for operation at speeds above 125 mph.

Criteria are defined by the conditions to be evaluated and the critical results from the evaluation. 

A classic example in the rail industry is the 800-kilopound (kip) buff strength requirement. The 

condition is an 800-kilopound load applied to the buff stops. Buff stops are design elements that 

support compressive loads into the carbody from the coupler components. The critical result is 

the deformation of the carbody, which must not be permanent. In other words, the carbody must 

return to its original shape when the load is removed. The conditions and critical results make up 

the criteria.

Procedures are defined as the analysis and test techniques applied to demonstrate compliance 

with the criteria. Continuing with the above example, compliance with the 800-kilopound buff 

strength requirement is typically demonstrated with a test. The coupler hardware is removed for 

the test, which allows access to the buff stops. During the test, the load is applied to the buff 

stops and incrementally increased until the total load reaches 800 kip. After the test, the load is 

removed, and the instrumentation is checked for indications of permanent deformation. The car 

is also visually inspected to verify that there is indeed no permanent deformation. The 

requirements and implementation of the test or analysis constitute the procedure.

The criteria and procedures are intended to provide an engineering-based methodology for 

comparing the crashworthiness and occupant protection performance of alternatively designed

equipment with that of compliant designs. Examples of analysis and test procedures that have 

been used to evaluate the performance of equipment are included in this document. The results of 

evaluations of alternatively designed equipment, applying such techniques, can be compared 

with the criteria values supplied in this document for compliant designs. In this manner, the 

performance of alternatively designed equipment can be assessed relative to the performance of 

compliant designs.
5

FRA‘s primary mission is to provide for the safety of Nation‘s railroads by administering the 

railroad safety laws and regulations. The rules of process for requesting waivers from these 

regulations are prescribed in 49 CFR 211. Railroads and operating authorities can petition FRA 

to waive regulations, including the crashworthiness regulations that apply to rail passenger 

equipment. As described in 49 CFR 211.9(c), each petition for waiver must contain sufficient 

information to support the action sought, including an evaluation of anticipated impacts. In this 

regard, the ETF‘s efforts have resulted in this report‘s guidance to the rail industry on what 

information FRA needs to make collision safety determinations on Tier I passenger equipment 

waiver requests.

FRA notes that, for purposes of obtaining a waiver, it is not necessary that every aspect of the 

crashworthiness and occupant protection performance for alternatively designed equipment be 

equal to or exceed that of compliant designs. If there are shortcomings in the performance of the 

equipment, other safety measures can be taken into account by FRA in making a waiver 

determination. For example, temporal separation has been used on the New Jersey Transit River 

Line—primarily to address the lower OVI (buff strength) of the equipment. With temporal 

separation, the likelihood is significantly reduced of a collision between a passenger train made 

up of noncompliant equipment and one made up of compliant equipment, or even a freight train. 

This is just one example. Additional measures to avoid or mitigate hazards can be used to 

provide for the overall level of system safety supporting a waiver request.

1.3 Scope

The criteria and procedures described in this document are specifically intended to apply to 

trainsets operated at speeds up to 125 mph that may need a waiver from (or, as appropriate under 

§ 238.201(b), approval of alternative compliance with) one or more of the following regulations:

§ 238.203 Static end strength.

§ 238.205 Anticlimbing mechanism.

§ 238.207 Link between coupling mechanism and carbody.

§ 238.209 Forward end structure of locomotives, including cab cars and MU

locomotives.

§ 238.211 Collision posts.

§ 238.213 Corner posts.

§ 238.215 Rollover strength.

§ 238.217 Side structure.

§ 238.219 Truck-to-car-body attachment.

§ 238.233 Interior fittings and surfaces.

In accordance with requirements in § 238.111, the equipment is subject to the prerevenue service 

acceptance testing. Pursuant to that section, a test plan is required for passenger equipment that 

has not been used in revenue service in the United States. Although the criteria and procedures 

are generally applied to the applicable individual structures of the trainset undergoing analysis, 

the overall intent of § 238.111 is to result in a cohesive design in which all parts function 

appropriately together. FRA notes that with respect to a trainset utilizing a CEM design, testing 

of the components incorporated with any CEM system may also be performed as part of a 

prerevenue service acceptance testing program.
6

These trainsets may require similar treatment under American Public Transportation Association 

(APTA) standards, such as APTA SS-C&S-016-99, Rev. 1 (updated 3/2004), Standard for Rowto-Row Seating in Commuter Rail Cars, and this document addresses these standards where 

appropriate.

1.4 Overview of Development

RSAC‘s advice and guidance have been integrated into these criteria and procedures. FRA 

established ETF of RSAC‘s Passenger Safety Working Group for this purpose. This task force is 

made up of members from the rail industry and FRA, with support from the Volpe Center. 

Industry representatives include railroads, labor organizations, suppliers, and their engineering 

consultants. FRA representatives include policy, legal, economic, and technical specialists.

The railroads have helped to determine that the information requested for demonstrating 

compliance with the alternative safety criteria is reasonably obtainable for submission to FRA. 

The labor organizations have helped to ensure that the resulting criteria and procedures are 

suitable for providing sufficient crashworthiness and occupant protection performance. The 

suppliers have helped to ensure that the assessment criteria are clear, that the procedures are 

practicable, and that the final criteria and procedures are design independent. As appropriate, the 

engineering consultants have helped with all of these goals. APTA has assisted with coordinating 

the participation of the railroads, suppliers, and engineering consultants.

1.5 Document Organization

This document is organized into five principal sections:

Section 1 – Introduction

1.1 Background

1.2 Objective

1.3 Scope

1.4 Overview of Development

1.5 Document Organization

1.6 Guidance Summary

Section 2 – Technical Basis

2.1 Background

2.2 Rail Equipment Crashworthiness Technology

2.3 Technical Basis for Criteria

Section 3 – Criteria

3.1 Requirement: Collision with Conventional Equipment

3.2 Requirement: Occupied Volume Integrity

3.3 Requirement: Colliding Equipment Override

3.4 Requirement: Connected Equipment Override

3.5 Requirement: Fluid Entry Inhibition

3.6 Requirement: End Structure Integrity of Cab End

3.7 Requirement: End Structure Integrity of Noncab End

3.8 Requirement: Roof Integrity

3.9 Requirement: Side Structure Integrity

3.10 Requirement: Truck Attachment
7

3.11 Requirement: Interior Fixture Attachment

3.12 Requirement: Occupant Protection Features

Section 4 – Example Procedures

4.1 Introduction

4.2 Guidance Summary

4.3 Requirement: Collision with Conventional Equipment

4.4 Requirement: Occupied Volume Integrity

4.5 Requirement: Colliding Equipment Override

4.6 Requirement: Connected Equipment Override

4.7 Requirement: End Structure Integrity of Cab End

4.8 Requirement: End Structure Integrity of Noncab End

4.9 Requirement: Truck Attachment

4.10 Summary and Next Steps

Section 5 – References
8

1.1 1.6 Guidance Summary

Table 1 contains a summary of the requirements, load cases, and criteria presented in this report.

It is meant only as a summary of those requirements addressed in this report and is not meant to 

include all applicable requirements for passenger equipment.

Table 1. Guidance Summary for Criteria and Evaluation

Requirement Summary of Load Case Summary of Criteria

Collision with 

conventional 

equipment

Alternatively designed train in collision with 

conventional locomotive-led train:

(a) 20 mph, cab car- or MU locomotive-led; or

(b) 25 mph, conventional locomotive-led.

Preserve occupied volume for passengers

Preserve survival space in operating cab

OVI

On the intended collision load path:

(a) 800 kip;

(b) 1,000 kip; and

(c) 1,200 kip

(a) No permanent deformation

(b) Limited permanent deformation

(c) Without crippling

Colliding equipment

override

Alternatively designed equipment collision with 

conventional locomotive:

(a) all equipment aligned; and

(b) consists offset 3 inches (in) vertical and laterally.

No override and

wheel lift minimized

Connected

equipment override

Alternatively designed equipment in collision with 

conventional locomotive, with 2-inch-vertical/2-inchlateral offsets of first car-to-car connection

No override and

wheel lift minimized.

Fluid entry

inhibition Based on design review

(a) Equivalent to 0.5-inch steel plate with 25,000 

pounds per square inch (psi) yield strength;

(b) Designed to inhibit the entry of fluids into the 

occupied area; and

(c) Affixed to structural members.

End structure 

integrity of cab end

(a) Absorb minimum of 135 ft-kip of energy for 

impact offset 19 in from longitudinal centerline;

(b) Absorb minimum 120 ft-kip of energy for impact 

aligned with sidewall.

No more than 10 in of longitudinal, permanent 

deformation

End (corner)

structure integrity of 

noncab end

(a) 150 kip at floor height;

(b) 30 kip 18 in above floor;

(c) 20 kip at ceiling height.

(a) Without failure;

(b) Without permanent deformation; and

(c) Without failure.

Roof integrity Equipment upside down, supported by roof (a) No occupied volume intrusion; and

(b) No more than 1/2 yield or buckling

Side structure 

integrity

Design requirements on sidewall stiffness and 

material properties

Vertical modulus (in3) > 0.3 × L

Horizontal modulus (in3) > 0.2 × L

Truck attachment

Scenario 3.1 plus either:

(a) 3g vertical, 1g lateral, 5g longitudinal; or

(b) 3g vertical, 1g lateral.

Static analyses: Without yielding; and

(a) Scenario 3.1: Avg. acc. < 5g and

Max. acc. < 10g; or

(b) Scenario 3.1: Trucks remain attached

Interior fixture 

attachment

Fixtures: 8/4/4g Longitudinal/lateral/vertical quasistatic load; and

Seats: 8g longitudinal dynamic pulse

Fixtures and seats remain attached

Seats

8g sled test with instrumented HIII ATDs per Rev. 2 

of APTA-SS-C&S-016-99

Seats must meet requirements in Rev. 2 of 

APTA-SS-C&S-016-99, including injury criteria

Note: Table for use as a summary only for the requirements noted.
9

2. Technical Basis

2.1 Background

This section describes the technical basis for how the selected criteria provide a comparable level 

of crashworthiness to the existing regulations.

Crashworthiness regulations and specifications are intended to result in equipment features that 

increase survivability in accidents. The traditional approach to rail equipment crashworthiness 

specifications is essentially car oriented, prescribing such things as the strength of the carbody 

and the strength of the attachment of the trucks. These features are intended to be effective for all 

of the accident conditions that the equipment may be subjected to in service. The modern 

approach to rail equipment crashworthiness adds train-oriented specifications and typically 

includes minimum survivability requirements for prescribed scenarios [1, 2, 3]. These scenarios 

are intended to bound the range of accidents that may occur in service. The modern approach to 

rail equipment crashworthiness does not replace the traditional approach; the modern approach 

extends from and modifies the traditional approach.

Modern specifications generally describe the crashworthiness performance desired of equipment 

with CEM features. Much research has been conducted on CEM [4, 5, 6]. CEM improves 

crashworthiness with crush zones at the ends of the cars. These zones are designed to collapse in 

a controlled fashion during a collision, distributing the crush among the unoccupied ends of the 

cars of the train. This occupant protection strategy preserves the occupied spaces in the train and 

limits the decelerations of the occupied volumes. CEM equipment has been demonstrated to 

protect all of the occupants in a train-to-train collision scenario for more than twice the closing 

speed of conventional equipment, when the CEM equipment has the same level of occupied 

volume strength as the conventional equipment [4, 7].

FRA Tier I crashworthiness regulations are largely traditional. Most of them apply to individual 

cars and their components. FRA is in the process of updating these regulations to better reflect 

modern technology. For over a decade, FRA, with the assistance of the Volpe Center, has 

conducted significant research on rail equipment crashworthiness [4, 7, 8, 9, 10] to establish a 

base of information from which to evaluate, amend, and develop regulations, specifically more 

performance-based regulations to respond to the needs of the industry. This research was used in 

developing the final rule prescribing minimum levels of energy absorption in highway-rail grade 

crossing scenario impacts, published on January 8, 2010 (see 75 Fed. Reg. 1180). Recognizing 

that railroads would like to use equipment designed to more performance-based, modern 

standards, FRA is accelerating its efforts to keep its crashworthiness regulations consistent with 

current safety technology.

Because the traditional and more modern approaches to crashworthiness are different, judgment 

is needed to make comparisons of the crashworthiness of equipment compliant with traditional 

requirements and equipment compliant with more modern requirements. In some cases, such as 

for OVI, it is possible to maintain essentially the same level of crashworthiness while reducing 

the traditional strength requirement. CEM crush zones can mitigate the reduction in occupied 

volume strength. In other cases, as in override prevention, the modern approach of controlling 

the shape of carbody crush supersedes the traditional approach of prescribing a static load that
10

the carbody must be able to support. In the development of the criteria and procedures, the goal 

has been to maintain the level of crashworthiness provided by the Tier I regulations in a manner 

that is as independent as practical from the detailed design features of the equipment.

2.2 Rail Equipment Crashworthiness Technology

In the design for crashworthiness, the first objective is to preserve a sufficient volume for the 

occupants to ride out the collision without being crushed. Excessive forces and decelerations also 

present a potential for injury to the occupants. Relatively large forces and decelerations can 

occur when an unrestrained occupant strikes an interior surface. Occupant impacts with the 

interior or collisions between occupants and loose objects thrown about during the collision are 

usually termed secondary collisions. The second objective of crashworthiness is to limit these 

secondary collision forces and decelerations to tolerable levels.

Preserving occupied volume is accomplished primarily with strength of the structure. If the 

occupant compartment is sufficiently strong, there will be sufficient, survivable space for the 

occupants. Secondary impacts are limited through a combination of structural crashworthiness 

and occupant protection measures. Allowing portions of the vehicle to crush in a predetermined 

manner can limit the forces applied to the structure surrounding the occupied volume and control 

the decelerations of the cars. Conventional practice is oriented toward making the individual cars 

uniformly strong and principally attempts to control the behavior of individual cars during a 

collision. The CEM approach is train-oriented, controlling the load into the occupied volume and 

apportioning the structural crushing to unoccupied areas throughout the train.

Occupant protection measures include specifying attachment strength requirements for interior 

fittings and strategies such as compartmentalization to literally contain the occupants within safe 

areas [11, 12, 13]. How hard the occupant strikes an interior surface during the collision depends 

on the deceleration of the train itself and the degree of ―friendliness‖ of that surface. There is a 

tradeoff between increased carbody crush strength and how fast an occupant strikes an interior 

surface. If a single car has a uniform crush strength, increasing the crush strength increases the 

deceleration rate of a colliding car. This, in turn, increases the speed at which an occupant 

impacts an interior surface in the decelerating car. For a consist of cars in a train, the issue is 

more complex. The deceleration of any particular car within a train is affected by the cushioning 

of the car ahead of it as well as the deceleration of the car behind it. In general, any 

crashworthiness strategy that better preserves the occupied volume, such as CEM, will make the 

secondary impacts more severe for the occupants in the interior. To maximize survivability, 

interior occupant protection strategies need to be designed to work in concert with structural 

crashworthiness strategies.

This section includes descriptions of technologies for providing OVI, providing CEM, and 

providing occupant protection.

2.2.1 Occupied Volume Integrity

In the conventional approach to passenger vehicle crashworthiness in the United States, the 

underframe of the car must maintain its integrity when subjected to a large compressive load at 

the coupler locations at either end of the car. The present strength requirement is for a car to 

remain elastic when subjected to 800,000 pounds (lb) of force loaded along the line of draft (the 
11

imaginary line running from the coupler at one end of the car to the other). This load is shown 

schematically in Figure 1.

Figure 1. 800,000 lb on Line of Draft

The practice of applying a large compressive load to the underframe of the car as a measure of 

occupant protection stretches back to the early 20th century. At that time, the U.S. Post Office 

began using baggage cars as railway post office (RPO) cars furnished with tables, chairs, and 

lighting installed so that postal clerks could sort mail while a train was en route. Unfortunately, 

in many railroad accidents of the day, these baggage cars offered little protection to the clerks 

inside, resulting in serious injuries and fatalities. To increase occupant protection, the Railway 

Mail Service (RMS) Specification was published in 1912. One requirement in this specification 

was for RPO cars to be capable of resisting 400,000 lb applied compressively along the line of 

draft without experiencing permanent deformation. In future versions of this specification, a 

factor of safety of 2 was included, bringing the effective load up to 800,000 lb [14].

In response to a number of fatal accidents involving compromised occupied volumes, the 

Association of American Railroads (AAR) issued a Recommended Practice in 1939 to address 

carbody structure. This Recommended Practice adopted a number of requirements of the RMS 

Specification, including the compressive strength of the carbody. In 1945, this recommendation 

was adopted into Standard S-034, ―Specifications for the Construction of New Passenger 

Equipment Cars.‖ Federal law has applied this requirement to all multiple-unit (MU) 

locomotives built new after April 1, 1956, and operated in trains having a total empty weight of 

600,000 lb or more. See 49 CFR 229.141(a)(1). It was not until 1999, however, that 49 CFR 

238.203 expanded this 800,000-pound static strength requirement as a Federal regulation 

applicable to all intercity passenger and commuter rail equipment.

This line of draft strength requirement has remained the cornerstone of OVI evaluation for nearly 

a century for several reasons. The pass/fail criterion of no permanent deformation anywhere in 

the car is straightforward to implement and can be readily examined visually and measured with 

strain gages. If the test is conducted properly and successfully, the vehicle remains in its original 

condition and can therefore enter service following the test. The nondestructive nature of the test 

makes it an economical test to perform as the first manufactured vehicle serves both as test 

article and proven, deliverable product.

In addition, the proof strength approach to crashworthiness provides additional crashworthiness 

benefits. Although the original intent of this approach was to maintain some level of protection 

from loss of occupied volume, this requirement has increased in its importance as other 

crashworthiness features have been incorporated within the car. For example, standards and 

regulations also specify the minimum strength of the corner and collision posts on a passenger 
12

vehicle. For an end frame to be successful in preventing intrusion from impacts above the floor, 

the structure supporting the end frame must itself be sufficiently strong. A strong end frame that 

is at the end of a weak occupied volume may prevent intrusion at the end of the car but cause 

loss of occupied volume elsewhere in the vehicle as collision loads travel through the occupied 

volume.

2.2.2 Crash Energy Management

Passenger rail equipment crashworthiness can be significantly increased if the force-crush 

behavior of the equipment is engineered to take place in a controlled manner. Sacrificial crush 

zones can be designed into unoccupied locations in cars, such as brake and electrical service 

closets and bicycle storage areas, as well lightly occupied areas without passenger seating, such 

as vestibules and stairwells. These zones are designed to crush gracefully, with a lower initial 

force and increased average force. With such crush zones, multiple cars are designed to share 

energy absorption during a collision, consequently preserving the integrity of the occupied areas 

by managing the collision energy. The approach of including crush zones is termed CEM.

Figure 2 is a schematic of the concept of CEM, with crush zones at the ends of all of the train‘s 

cars.

Figure 2. Schematic Illustration of Crush Zone Locations in Commuter Rail Passenger 

Train 

CEM extends from conventional crashworthiness design practice. The car‘s occupied volume 

must have sufficient strength to support the crush zones designed into it without collapsing.

Greater occupied volume strength allows greater crushing forces to be supported; in turn, greater 

amounts of energy can be absorbed for a given crush distance.

Figure 3 shows the prototype cab end crush zone design that was developed as part of FRA 

research. The cab car crush zone includes four key elements:

 A pushback coupler mechanism

 A deformable anticlimber arrangement

 An integrated end frame, which incorporates an engineer‘s compartment

 Roof and primary energy-absorbing elements
13

Figure 3. Cab Car Crush Zone

Each component is designed to operate in sequence during an impact. The pushback coupler 

accommodates the coupler of the impacting equipment such that the anticlimber and integrated 

end frame engage the vehicle. As the anticlimber deforms, it conforms to the impacting 

equipment and distributes the load over the integrated end frame. The integrated end frame 

transmits the impact load to the energy absorbers. The engineer‘s compartment can be pushed 

straight back into unoccupied space designated for service closets.

Superior crashworthiness performance of CEM equipment has been demonstrated with full-scale 

impact tests. In the train-to-train test of conventional equipment, the colliding cab car was 

crushed by approximately 22 feet (ft) and overrode the locomotive, eliminating the space for the 

engineer‘s seat and for approximately 47 passenger seats [15]. During the train-to-train test of 

CEM equipment, the front of the cab car was crushed by approximately 3 ft, and the crush was 

propagated back to all of the unoccupied ends of the trailing passenger cars. The controlled 

deformation of the cab car prevented override. All of the space for the passengers and crew 

remained intact [16]. The impact speed for both train-to-train tests was 30 mph. Figure 4

includes frames from high-speed movies showing the colliding equipment interactions.

Sliding Sill Fixed Sill

Pushback Coupler

Primary Energy Absorber

Roof Energy Absorber

Deformable 

Anti-climber

Interlocking

Anti-climber

Integrated 

End Frame

Engineer’s

Compartment
14

Figure 4. Frames from High-Speed Movies of Conventional (top) and CEM (bottom) 

Train-to-Train Tests

Compared with CEM-designed equipment, the interactions of impacting conventional North 

American passenger rail equipment are more likely to be uncontrolled, because of more 

haphazard structural damage (crush), override, or buckling between cars. Structural damage 

tends to be focused on the colliding equipment and those cars that are immediately trailing. 

When passengers are in a leading cab car, structural damage can intrude into the occupied 

volume, resulting in a loss of survival space. Override is often associated with substantial loss of 

occupied volume and consequent fatality. The coupling arrangement between cars can lead to 

lateral buckling of the trainset. Examples of uncontrolled car-to-car interactions are shown in 

Figure 5.

Figure 5. Example of Uncontrolled Car-to-Car Interactions

Uncontrolled Crush: 

Focused on One Car

Uncontrolled Load 

Path: Derailment 

Lateral Buckling

Override: Carbody 

Overwhelmed
15

Although there are limitations to the amounts of energy CEM can safely handle, CEM helps to 

minimize these risks by using equipment structures that are designed to gracefully deform when 

overloaded. Within the capabilities of the CEM design, graceful deformation of the equipment 

structures allows override to be prevented, keeps the trailing equipment from buckling laterally, 

and distributes structural damage to the unoccupied areas of the train. Management of the impact 

interface is essential to preventing override. Such management can be effectively accomplished 

with a pushback coupler mechanism, a deformable anticlimber arrangement, an integrated end 

frame, and energy-absorbing elements. Pushback coupler mechanisms are effective in preventing 

lateral buckling of coupled equipment. Deformable anticlimber arrangements promote the 

engagement of vehicle ends, preventing override. Integrated end frames and energy-absorbing 

elements are essential to distributing crush to the unoccupied areas. Examples of controlled carto-car interactions are shown in Figure 6.

Figure 6. Examples of Controlled Car-to-Car Interactions

2.2.3 Occupant Protection

A primary collision is a collision that occurs when a moving train impacts another object. When 

this happens, the train occupants continue moving at the train‘s initial speed while the train 

rapidly decelerates. A secondary impact occurs when an occupant collides with an interior 

surface, such as the seatback in the row ahead, as shown in Figure 7. An occupant may survive a 

collision with an interior surface (e.g., seat back, wall, or table) during an accident if the forces 

and accelerations are within acceptable human tolerance levels.

Controlled crush: 

Distribute crush 

through train

Control load path: 

Prevent lateral 

buckling

Engagement: 

Prevent 

override
16

Figure 7. Computer Simulation Illustrating Occupant Kinematics

The methods of protecting occupants and minimizing the forces and accelerations they 

experience include controlling the deceleration of the vehicle, compartmentalizing the occupants, 

providing compliant impact surfaces, and using passenger restraints such as lap and shoulder 

belts. Vehicle deceleration is a function of the structural design of the carbody. The gentler the 

initial deceleration of the vehicle, the lower the speed at which the occupant will strike the 

interior. (Section 3 discusses structural crashworthiness and occupant protection measures in 

detail, including strategies for controlling the initial deceleration of the cars in a train during a 

collision.)

Compartmentalization is a strategy for providing occupant protection during a collision by 

limiting the occupant‘s range of motion. If the distance an occupant can travel in free-flight is 

limited, the occupant‘s speed relative to the interior can be limited, resulting in a more benign 

secondary impact. Compliant impact surfaces are those that are sufficiently soft and/or 

deformable, which can absorb energy and limit forces imparted to the occupant during the 

secondary collision. If the interior surfaces are made sufficiently compliant, the maximum forces 

and decelerations experienced by the occupant can be limited to human tolerance levels.

Occupant restraints act to prevent or minimize the severity of secondary impacts with the interior 

and to secure the occupant to the mass of the car. Once the motion of the occupant is constrained, 

occupant impacts with interior surfaces can be avoided or limited to particular surfaces, which 

can be specifically designed to provide a less hostile impact.

The severity of the secondary impact is governed principally by two factors: the secondary 

impact velocity (SIV) and the force-deflection behavior of the impact surface. As described 

above, the SIV is generally a function of distance traveled, which is related to seating 

configuration. Figure 8 shows an SIV plot that corresponds to an 8g, 250-millisecond 

acceleration pulse.

1

The figure correlates SIV with the approximate travel distance associated 

 

1 The 8g crash pulse is specified for seat testing requirements in 49 CFR 238.233, Interior Fittings and Surfaces, and 

in APTA-SS-C&S-016, Revision 2, Standard for Passenger Seats in Passenger Rail Cars.
17

with various seating configurations. Typically, a shorter travel distance correlates to a lower SIV, 

because relative velocity generally increases with distance traveled.

Figure 8. Representative SIV Plot Corresponding to Various Seating Configurations

SIV can be used to assess the crashworthiness and occupant protection performance of different 

interior configurations. The plot in Figure 9 identifies SIV severity ranges and possible measures 

for minimizing the risk of injury. SIVs of less than 10 mph are generally survivable with 

conventional interior equipment. For SIVs between 10 and 25 mph, the interior environment is 

deemed survivable if compartmentalization is ensured, and passive safety modifications are 

provided in the seat and table designs. Above 25 mph, active protection features (i.e., air bags, 

inflatable structures, lap and shoulder belts, etc.) are necessary to mitigate the risk of injury.

FRA-sponsored occupant protection research has mostly focused on strategies of 

compartmentalization to reduce injury risk. SIV has been used during the research process to 

develop energy-absorbing seats and tables that would limit injury indices to within human 

tolerance levels during full-scale testing. Prior to testing, the longitudinal acceleration-time 

history, or crash pulse, of each car was predicted using a collision dynamics model. The crash 

pulse was integrated to calculate velocity and displacement, which were then cross-plotted to 

evaluate the SIV in each car for different seating configurations. The necessary forcedeformation behavior of the seats and tables could then be calculated based on the estimated 

SIV.
18

Figure 9. Example SIV Plot with Injury Interpretation

Improved Workstation Tables

Strategies to mitigate the potential for injury due to impacts with workstation tables have been 

developed through a cooperative agreement between FRA and the Rail Safety and Standards 

Board (RSSB) of the United Kingdom [18]. RSSB and FRA have shared the results of ongoing 

work to improve the safety of passengers seated at tables. RSSB has loaned FRA its 

anthropomorphic test dummy (ATD), the H3RS. This test dummy includes abdominal sensors to 

measure the loads imparted by workstation tables under collision conditions. This test dummy 

has been used to measure the performance of a baseline table and an improved table during fullscale impact tests of CEM equipment.

The improved workstation table was designed to meet crashworthiness and occupant protection 

performance, functionality, and geometry requirements [18]. Several tables were fabricated and 

tested both quasi-statically and dynamically, including two occupant experiments on the fullscale train-to-train impact test of CEM equipment. Figure 10 shows a sketch of the table design.
19

Figure 10. Design of an Improved Workstation Table

This design builds from a center support I-beam, which is cantilevered from the car wall, and 

extends laterally from the wall to the aisle. The center support I-beam is designed to remain 

attached under the impact loads from two occupants during a collision to help ensure that the 

occupants remain compartmentalized. It also supports the table under service loads. The tabletop 

is constructed of a crushable, energy-absorbing aluminum honeycomb, oriented so that cells are 

aligned in the vertical direction. This allows for the table edge to achieve the target longitudinal 

force-crush characteristic while remaining stiff enough to meet the service load requirements.

The melamine tabletop provides a rigid surface to preserve the functionality of the table. During 

impact, the melamine top is designed to separate from the honeycomb in such a manner that it 

will not adversely affect the force-crush characteristic. The rubber edge distributes the load from 

the melamine top and the aluminum honeycomb to provide a more benign impact surface to the 

occupants during a collision.

The workstation table was tested onboard the cab car in the CEM train-to-train test [17]—the test 

shown in the lower portion of Figure 4. The objective of the table experiments was to 

demonstrate the performance of this improved table design. The primary crashworthiness and 

occupant protection requirement is that the occupant is compartmentalized. A secondary 

objective was to evaluate the table against the crashworthiness and occupant protection design 

requirements. These requirements, determined during the development of the improved table, 

were designed to help ensure that the upper abdominal injury risk to the occupant is reduced 

without introducing other injury risks. The test dummy was outfitted with instruments to make 

the measurements needed to evaluate the potential for injury. A pretest MADYMO [18] 

computer model was used to simulate the occupant response for each table experiment using the 

predicted crash pulse from the pretest collision dynamics model [19]. All of the predicted 

measurements were below the maximum acceptable injury criteria values.

Figure 11 shows pre- and posttest photographs of a table test conducted as part of the CEM trainto-train test. The table remained attached to the car structure and compartmentalized the 
20

occupants. The table edge performed as intended. The melamine top separated from the 

aluminum honeycomb and folded along the scored edges. The aluminum honeycomb crushed 

between 5 and 6 in, with a peak force of roughly 2,000 lb. This is a significant reduction from the 

peak load measured in the baseline table test. All of the computed injury criteria values were 

within accepted limits [18].

Figure 11. Pre- and Posttest Photos of Table Test

Improved Commuter Seats

An optimized commuter seat was developed to help protect occupants under the severe collision 

conditions expected in the leading cab car of a CEM train-to-train impact test. The results from 

the two-car CEM test indicated that an improved seat design was necessary to meet occupant 

protection requirements in the leading cars of a CEM consist. Pretest computer modeling 

indicated that the SIV in the cab car of the CEM train-to-train test could approach 25 mph, 

depending on the seating configuration. For this reason, rear-facing seats were proposed in the 

cab car as a strategy to mitigate the high SIV in the lead car. Forward-facing seats were proposed 

in the first passenger car behind the cab car.
21

During development of the new seat, several requirements were established for occupant 

protection and seat performance under test conditions similar to those expected in the CEM trainto-train test [16]. To meet the occupant protection requirements, the ATDs must be 

compartmentalized, and the head, neck, chest, and femur injury criteria must be within the limits 

defined in 49 CFR Part 571, 208 - Occupant Crash Protection [21], which is used by the 

automotive industry. The standards in the APTA Standard for Row-to-Row Seating in Commuter 

Rail Cars [22] must also be met, which include seat performance criteria. The seat must remain 

attached to the test sled at all attachment points, and the permanent seat deformations must not 

significantly impede an occupant from standing and exiting the seat. Seat cushions must also 

remain fastened to the seat frame.

The new seat design is based on an existing two-passenger seat design that meets the APTA 

standard for row-to-row seating in commuter rail cars. The principal modifications to this design 

are a third passenger seat, stronger seat backs, taller headrests, and reinforced attachments to the 

floor and wall. When compared with the M-style seat, the prototype seat is stiffer, taller, and 

more modular, with padding on the head impact surface and a knee bolster to transfer loads from 

the knees into the seat frame. Figure 12 shows a schematic of the prototype seat structure.

Figure 12. Schematic of Prototype Commuter Seat

Sled tests were conducted using three instrumented ATDs in each test. The rear-facing seat was 

tested using a 12g, 250-millisecond (ms) triangular crash pulse, which approximates the collision 

conditions in the leading cab car of the CEM train-to-train test. The forward-facing seat was 

tested using the standard 8g, 250-millisecond triangular crash pulse, which approximates the 

collision conditions in the first passenger car behind the cab car. Figure 13 and Figure 14 show 

pre- and posttest photographs from the 8g forward-facing sled test and the 12g rear-facing sled 

test, respectively.
22

Figure 13. Pre- and Posttest Photos of Forward-Facing 8g Sled Test

Figure 14. Pre- and Posttest Photos of Rear-Facing 12g Sled Test

The final test results indicate that all test requirements were met: the seats remained attached to 

the test sled; the ATDs were compartmentalized; all the injury criteria were within defined 

tolerance thresholds; and all the seat cushions remained attached.

2.3 Technical Basis for Criteria

The criteria are both the conditions to be evaluated and the metrics for assessment. One example 

is the traditional buff strength requirement [23] in which a load of 800 kip applied to the buff 

stops is the condition to be evaluated, and no permanent deformation is the assessment metric.

Another example is FRA‘s Tier II CEM scenario [2] in which a collision at 30 mph with similar 

like train is the condition to be evaluated, and preservation of the occupied volume is the 

assessment metric. This style of criteria separates out the procedure used to evaluate the 

condition(s) and to determine the value of the metric(s). In theory, one could use either analysis 

or testing to evaluate either example.

The criteria are influenced by the current Tier I regulations [23], which apply to passenger 

equipment operated at speeds up to 125 mph, and by the current Tier II regulations [2], which 
23

apply beyond 125 mph up to speeds not exceeding 150 mph. The criteria have also been 

influenced by European standards EuroNorm (EN) 12663 [24], which includes requirements for 

OVI, and EN 15227 [3], which includes requirements for CEM. Several different categories of 

equipment are addressed in the European standards. These categories are based on the equipment 

type and operating environment in revenue service. The CEM requirements of EN 15227 

essentially overlay the traditional strength-based requirements in EN 12663. In a similar manner, 

the CEM specifications developed for Metrolink [1] overlay the current Tier I requirements [23].

Consequently, a train built to the Metrolink CEM specifications will meet the Tier I structural 

requirements. In addition, the Metrolink CEM requirements are intended to provide a level of 

crashworthiness that significantly exceeds the level provided by the Tier I requirements alone.

Above these influences, the criteria and procedures were developed to take advantage of the 

latest technology in rail equipment crashworthiness.

The numerical values of the pass/fail criteria have been selected to provide a level of 

crashworthiness equivalent to the current Tier I regulations. In some cases, aspects of the 

regulations have been relaxed; others have been increased or supplemented. For example, the 

OVI requirements have been relaxed from the current regulations and criteria for preservation of 

the occupied volume for a collision with a conventional locomotive-led train have been added to 

compensate. In other cases, such as for roof integrity, the existing regulations can be applied to 

alternatively designed equipment and are unchanged.

Because the latest technology in rail equipment crashworthiness has been used to develop the 

criteria and procedures, aspects of the resulting criteria and procedures are fundamentally 

different from their corresponding regulations. Although technical results from sophisticated 

analyses and tests have been necessary, judgment was also needed to develop the criteria and 

procedures. This judgment was provided by ETF and ultimately accepted by FRA. ETF is a 

government/industry working group, organized under the auspices of RSAC [25]. This section 

summarizes the technical information that helped inform the ETF‘s judgments.

For describing the technical basis, the recommended criteria are grouped into three categories:

- Train-level

- Car-level

- Interior occupant protection

The train-level requirements are based on a train collision scenario. In the prescribed scenario, 

the space for the crew and passengers is to be preserved, the colliding equipment is not to 

override, coupled equipment is not to override, and the trucks are to remain attached. These 

requirements are significantly different from the existing Tier I regulations. Indeed, there are no 

specific train-level or scenario-based requirements in Tier I for crashworthiness.

The car-level requirements are intended to provide a robust occupied volume that can support the 

demands of the CEM features without being overloaded and can also preserve the occupied 

volume in a range of accidents, including highway-rail grade crossing collisions and derailments.

These car-level requirements essentially correspond to the Tier I regulations, except for OVI.

The OVI requirement is substantially different from the traditional 800-kilopound buff strength 

requirement. The traditional requirement can be difficult to apply to designs that differ from 
24

traditional North American passenger car designs. The OVI requirement has been developed 

with the intent that it may be applied to a wide range of equipment designs.

The interior occupant protection requirements are based on APTA standards. FRA and APTA 

have worked together closely to develop these standards, and APTA has diligently applied the 

results of FRA‘s research in maintaining and updating them.
25

2.3.1 Train-Level

There are four train-level criteria:

 Scenario

 Colliding equipment override

 Connected equipment override

 Truck attachment

Scenario

In the scenario, shown in Figure 15, a cab car- or an MU locomotive-led alternatively designed 

train collides with a conventional locomotive-led passenger train. The principal requirement is 

that all of the space for the passengers and crew be preserved for a closing speed of 20 mph.

Figure 15. Schematic of Collision Scenario

The scenario criteria describe the information needed to compare the overall effectiveness of the 

OVI and other crashworthiness features of the alternatively designed equipment with the overall 

effectiveness of equipment designed to Tier I standards. In combination with the OVI criteria, 

the scenario criteria are intended to ensure that the space for the passengers and crew is 

preserved under moderately severe accident conditions. Uniquely for the scenario criteria, there 

is no directly corresponding FRA regulation.

Tier I-compliant equipment performance in the prescribed scenario is dependent on a number of 

factors, including train makeup—whether the equipment is push-pull or MU and the number of 

cars in the consist [26]. The maximum collision speed for which all of the space for the 

passengers and crew is preserved for single-level equipment ranges from about 10 mph for a 

long train pushed by a locomotive to about 18 mph for a short MU train. There is some 

uncertainty in this range, and actual performance may be somewhat better or worse. The 20-mile 

per hour speed used in the scenario criteria, then, is an upper estimate of what Tier I-compliant 

equipment may achieve in the prescribed scenario.

Figure 16 shows a photograph from the accident that occurred in Placentia, CA, on April 23, 

2002 [27]. In this accident, a locomotive-led freight train collided with a cab car-led passenger 

train at a closing speed of approximately 22 mph. Overall, 161 of the passengers and crew were 

transported to local hospitals. Two of these passengers sustained fatal injuries. Both of the 

passengers who sustained fatal injuries were seated in a facing seat configuration with an 

intervening workstation table. There was sufficient energy in this collision to cripple the 

structure of the impacting cab car. The majority of the structural deformation occurred at the rear 

of the cab car in the location of the stairwell. There was sufficient deformation that the 

passengers could not pass through that area and had to be evacuated through side windows. In 

essence, the conditions of this accident were just beyond the crashworthiness capabilities of this 

equipment.
26

Figure 16. Aerial Photograph of Placentia Accident [27]

EN 15227-compliant equipment performance in the prescribed scenario has been estimated,

based on information submitted, as part of a recent waiver request by Caltrain [28]. The 

crashworthiness of the EN-compliant equipment was evaluated using the same model as the 

Tier I-compliant equipment [26]. The primary inputs to the model are the masses of the 

equipment and the force-crush characteristics. The mass of the initially moving, EN-compliant 

train is 3,800 kip, and the mass of the Tier I-compliant locomotive-led train is 5,010 kip. The 

estimated force-crush characteristics are shown in Figure 17. As seen in the plots, the load 

required to cripple the Tier I-compliant equipment is greater than the load required to cripple the 

EN-compliant equipment. However, the energy required to cripple the EN-compliant equipment 

is greater than the energy required to cripple the Tier I-compliant equipment.
27

Figure 17. Estimated Force-Crush Characteristics for Tier I-Compliant (blue) and ENCompliant (red) Equipment

Figure 18 shows the distribution of interface crush in the EN-compliant train for collision speeds 

of 15 and 20 mph. For speeds up to 20 mph, there is no intrusion into the occupied volume. The 

energy-absorbing features are effective in keeping the load applied to the occupied volume 

below the load needed to cripple the structure.

0.0E+00

5.0E+05

1.0E+06

1.5E+06

2.0E+06

2.5E+06

3.0E+06

0 5 10 15 20

Crush (ft)

Force (lbf)

EN-Compliant CEM

Conventional

Estimated Car Body Strength

0.0E+00

5.0E+05

1.0E+06

1.5E+06

2.0E+06

2.5E+06

3.0E+06

0 5 10 

Crush (f

Force (lbf)

Crush (ft)

Cab End Non-cab End

Crippling Load Crippling Load
28

Figure 18. Distribution of Crush in the EN-Compliant Train in Prescribed Scenario, 

Closing Speeds of 15 and 20 mph

Figure 19 shows the SIV at the center of gravity (CG) of each of the cars in the EN-compliant 

train for the scenario conditions at 20 mph. The plot also shows the SIV associated with the 8g 

deceleration pulse described in the Tier I requirements [23] and in the APTA standards [29]. The 

SIVs of the EN-compliant equipment for a 20-mile per hour closing speed collision are less than 

those associated with the 8g crash pulse. These results indicate that interior seats and other 

fixtures that are compliant with FRA regulations and APTA standards would be effective in 

protecting the occupants of the EN-compliant equipment.

Figure 19. SIV Plot for EN-Compliant Equipment

Crush occurs in crush zones and does not intrude into 

occupant volume. 

Occupant volume intrusion at 

the non-cab interfaces 

occurs at 2.5 ft.

Occupant volume 

intrusion at the 

collision end occurs 

at 2.9 ft.

0

5

1 0

1 5

20

2 5

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

Velocity (mph)

Distance (ft)

Leading Cab Car

Second Car

Third Car

Trailing Cab Car

8 g
29

The overall conclusion is that equipment compliant with the traditional strength-based 

requirements of EN 12663 and the CEM requirements of EN 15227 provides a level of 

crashworthiness in train-to-train collisions that is comparable to equipment compliant with the 

strength-based requirements of the Tier I regulations. There is a concern for high-energy 

collisions. If a cab car-led Tier I-compliant train were to collide with a cab car-led EN-compliant 

train at a speed greater than approximately 20 mph, the capacity of the CEM features would be 

exhausted. The stronger occupied volume of the Tier I-compliant train could allow it to 

potentially overwhelm the EN-compliant train. As a result, the EN-compliant train may lose a 

significant portion of its occupied volume; the extent of the damage would depend on how much 

the collision speed exceeds 20 mph. However, if two cab car-led Tier I-compliant trains were to 

collide at a speed above approximately 20 mph, one would likely override the other; again, the 

extent of damage would depend on how much the collision speed exceeds 20 mph. The 

overridden train may experience a significant loss of its occupied volume. In both cases, it is 

difficult to predict the outcome with confidence. As best as can be judged, the total 

consequences—injuries and fatalities—of either 20-mile per hour collision would likely be the 

same.

Colliding Equipment Override and Connected Equipment Override

The colliding and connected car override criteria prescribe the kinematic behavior of the 

equipment for ideal and offset conditions. The ideal condition is that with the equipment 

positioned at its design height and centered on the track. The offsets for colliding equipment—3 

in vertically and 3 in laterally—are based on the offsets used by Metrolink in procuring their 

equipment with CEM features [1]. The offset conditions are intended to help ensure that the 

override features are robust. The offset initial conditions are illustrated in Figure 20.

Figure 20. Illustration of Offset Conditions for Colliding Equipment

The lateral offset for connected pieces of equipment is based on the conventional and CEM twocar impact tests [30, 31]. The location of the prescribed connected car offsets is at the first 

connected interface in the train, as shown in Figure 21. These offsets have different influences on 

coupled equipment than on articulated equipment. Offset coupled equipment is illustrated in 

Figure 22, and offset articulated equipment is shown in Figure 23.

Close-up Side View Close-up Bottom View

3”

Vertical 

Offset

3”

Lateral 

Offset
30

Figure 21. Location of Offsets in Moving Consist: First Connected Interface

Figure 22. Illustration of Offsets for Coupled Cars

Figure 23. Illustration of Offsets for Articulated Cars

Figure 24 shows the interaction of colliding equipment for both a train-to-train test [15] and an 

actual train-to-train collision in Beverly, MA [32]. In both cases, the colliding cab car overrode 

the colliding conventional locomotive. The deformation mode observed in the test involved the 

end frame of the cab car engaging the short hood of the conventional locomotive. Deformation of 

the cab car structure behind the end frame led to the override. In essence, the underframe 

structure deformed into a ramp, allowing the cab car to override the conventional locomotive.

Photographs from the Beverly, MA, accident indicate that the same mechanism allowed override 

in the accident as in the test. In both the test and the accident, the anticlimbing features were 

effective; the failure occurred in the underframe structures.

2 inch vertical and 

lateral offsets
31

Figure 24. Cab Car Interaction with Conventional Locomotive in a Collision

Figure 25 shows analysis predictions and test images for the interaction of colliding CEM 

equipment [15]. The test conditions for the CEM equipment shown in Figure 25 are the same as 

the test conditions for the conventional equipment shown on the left in Figure 24. In both tests, a 

passenger train led by a CEM-equipped cab car moving at 30 mph collided with a standing 

conventional locomotive-led train of equal weight. As can be seen in both the analysis and test 

footage, the interaction of the colliding CEM equipment is very different from the colliding nonCEM equipment interaction shown in Figure 24. As suggested by the annotations in Figure 25, 

the sequence of events is different for non-CEM and CEM equipment. In this case, the CEM 

features increase the speed at which override would occur. For this particular equipment, the 

energy-absorbing features would be exhausted at some speed above 30 mph. Once this occurs, 

the main structure may be overloaded and may fail in a manner similar to the non-CEM 

equipment.
32

Figure 25. CEM Cab Car Interaction with Conventional Locomotive in a Collision

Figure 26 shows connected equipment interaction for both an impact test [15] and a train-to-train 

collision [34]. In both cases, override was inhibited, and the end structures of the two cars 

transferred load without any intrusion into the occupied volume. The end frames, however, did 

not fully align themselves. In both cases, the collision posts were essential to the transfer of load.

The schematic at the bottom of the figure illustrates the misalignment observed in the test. The 

car as shown on the right of the schematic is attempting to override the car on the left. The 

vertical motion is arrested by the interactions of the couplers with the couplers‘ support 

structures. The longitudinal load is transferred from the end beam of the car on the right to the 

collision posts of the car on the left. The deformation damage seen in the car from the accident is 

consistent with the load supported by the car on the left in the schematic. Override between 

coupled passenger cars is rare in the United States; no known cases have occurred in more than 

30 years.
33

Figure 26. Non-CEM-Connected Equipment Interaction in a Collision

Figure 27 shows analysis predictions and test measurements for the interaction of connected 

CEM equipment [16]. For the CEM equipment, the end frames of the cars are aligned. For this 

design, vertical displacement is controlled by an interlocking anticlimber mounted on the end 

beam. Longitudinal load is transferred through the end beams and also through the 

antitelescoping (AT) plate at roof level. Similarly to the behavior of colliding equipment, the 

sequence of events for connected CEM equipment is different from the sequence for connected 

non-CEM equipment.
34

Figure 27. CEM Connected Equipment Interaction in a Collision

High longitudinal forces develop throughout the train during a collision. For both the colliding 

equipment and connected equipment, override occurs as a result of the vertical loads that develop 

because the high longitudinal loads are not perfectly aligned. Small pitch angles of the cars can 

lead to significant vertical loads. As the car structures deform, the vertical loads can increase in 

an unstable manner. Conventional practice for preventing climbing allows misalignments and 

provides for a high vertical load capacity. CEM is oriented toward minimizing the 

misalignments, thereby minimizing the vertical loads. Because the two approaches are 

fundamentally different, their specifications are different. Evaluating equivalence between 

anticlimbing features designed using conventional practice and those designed using a CEM 

approach involves technical judgment.

The potential for offset between colliding and connected equipment comes principally from three 

sources: variations in track geometry, suspension response, and wheel wear. These sources are 

illustrated in Figure 28 for vertical offsets and in Figure 29 for lateral offsets.
35

Figure 28. Illustration of Principal Sources of Vertical Offset between Cars

Figure 29. Illustration of Principal Sources of Lateral Offset between Cars

The colliding and connected equipment override criteria are fundamentally different from the 

corresponding FRA regulations. The regulations prescribe load capacity of particular features in 

their undeformed state. The criteria prescribe kinematic behavior; for the scenario conditions, the 

underframes must remain aligned within limits, and the wheels of the trucks must not lift from 

the rails by more than the specified limited amount as the CEM features of the car structure 

crush. Because of this fundamental difference in approach, it is difficult to assess equivalence in 

technical terms. In terms of intent, in promulgating the requirements, FRA stated: ―The purpose 

of the anti-climbing mechanism is to prevent the override or telescoping of one passenger train 

• Track Geometry

– The deviation from uniform profile on either rail 

at the mid-ordinate of a 62-foot chord may not 

be more than 11⁄4 inches for Class 5 Track

• Suspension Travel

– Dprimary ~ ±1 inch

– Dsecondary ~±2 inches

• Wheel Wear

– Rnew – Rcondemn ~ 1 1⁄2 inches 1 1/2 inches

Note: Extreme combination of sources allows more than 5 inch offset between adjacent cars.

Primary

Secondary

• Track Geometry (Class 5)

– The deviation of the mid-offset 

from a 62-foot line may not be 

more than 3⁄4 inch

– Gagemax – Gagemin = 1 1⁄2 inches

• Suspension Travel

– Dprimary ~ negible

– Dsecondary ~ ±2 inches

• Wheel Wear

– Tnew – Tcondemn ~ 1⁄2 inch

Note: Extreme combination of sources allows more than 5 inch offset between adjacent cars.

Flange 

Thickness

Secondary Gage Left Rail Right Rail

Reference

Alinement
36

unit into another in a derailment or collision. . . . The potential for override to occur is influenced 

by the dynamic motions of the cars, the relative heights of the vehicles‘ underframes, and the 

changing geometry of the vehicles‘ structures as they crush during the collision. . . . While all 

three factors play a role in the occurrence of override, results of actual collisions indicate that the 

changing geometry of the car structures as they crush—which, in effect, creates a ramp during 

the collision—can overwhelm the influence of the difference in sill heights‖ [23]. The intent of 

the criteria is the same as the intent of the regulation, even though the technical approach is very 

different.

Truck Attachment

The truck attachment criteria are based on the requirements of EN 12663 with the addition of a 

dynamic, longitudinal load requirement. In brief, for the scenario conditions, the dynamic 

requirement is that the average deceleration of the car should be less than 5g, and the peak 

deceleration of the truck should be less than 10g. The purpose of the dynamic longitudinal 

requirement is to ensure that the quasi-static load assumption is appropriate. As an 

approximation, about twice the permanent-deformation load is required to fail the attachment 

designed not to deform plastically [35]. Further, a dynamic amplification factor of 2 is typically 

used for linear elastic systems [36]. An attachment designed for a quasi-static load of 5g without 

permanent deformation should be able to support a dynamic load of 10g without failure.

Truck attachments compliant with Tier I requirements are effective in many accidents but have 

not been effective in retaining the trucks in all circumstances. Figure 30 shows accidents in 

which the trucks have remained attached. Figure 31 shows accidents and a full-scale test in 

which trucks have become detached.
37

Figure 30. Accident Conditions in Which Trucks Have Remained Attached

Figure 31. Accident Conditions in Which Trucks Have Become Detached

Some of the accident conditions in which trucks remained attached are similar to accident 

conditions in which trucks became detached. The reason for detachment is not in the conditions 

but in the equipment. For some truck attachments, a relatively soft longitudinal suspension is 

used with a hard stop; for others, a relatively stiff longitudinal suspension is used with a stop. If 

Lake City 2000

Crescent City 2002

Syracuse 2001

Secaucus 1996

1

Chicago 2007

Chatsworth 2008

Chicago Metra 2005 Single Car Test of Multi-level 

Equipment 2007
38

the suspension is initially soft, the stop can be loaded abruptly, which can cause it to fail. If the 

suspension is initially firm, then the stop is loaded more smoothly and is therefore less likely to 

fail. This difference in attachment is illustrated in Figure 32.

Figure 32. Illustration of the Influence of Longitudinal Suspension on Suspension Stop 

Loading

CEM features are unlikely to influence truck forces in a derailment or rollover. CEM features 

may increase the forces acting on truck attachments in a collision. Although CEM features may 

limit the peak acceleration acting on the carbody, the force acting on the truck is more closely 

related to the average deceleration. The load between the carbody and the truck is determined by 

the impulse imparted to the truck, which is related to the average deceleration of the carbody.

Because CEM features act to increase average deceleration to better preserve occupied volume 

[37], the inclusion of CEM features may increase the severity of the impulse imparted to the 

trucks in a collision.

In promulgating the current requirements, FRA stated: ―Whether the truck separates from the car 

body if the car rolls over, or . . . from being sheared off, the truck may become a hazardous 

projectile. . . .‖ For the 2g vertical load requirement specifically, FRA stated: ―The intent . . . is 

to prevent the truck from separating from the car body if it is raised or rolls over.‖ For the 

250,000-pound load requirement in any horizontal direction, FRA stated: ―The fundamental 

reason . . . is to prevent the truck from shearing off. . . . This force may be possessed by one rail 

vehicle . . . as it collides with the truck of another rail vehicle. . . .‖ [23].

Table 2 summarizes and compares the requirements of the CFR and the criteria for truck 

attachment. Overall, the criteria for truck attachment are intended to be equivalent to the current 

requirements, but there are differences in the longitudinal, lateral, and vertical requirements.

Car body

Truck

V

Car body

Truck

Car body

Truck

Car body

Truck

V

Gap

Elastomeric 

Block

Step 1. Car 

Decelerates Rapidly

Step 2. Truck Loads 

Stop Smoothly

Step 3. Stop 

Remains Intact

Step 1. Car 

Decelerates Rapidly

Step 2. Truck 

Impacts Stop

Step 3. Stop Fails
39

Table 2. Summary of CFR Requirements and Criteria for Truck Attachment 

Direction CFR Criteria

Longitudinal Load: 250 kip

Pass/fail: Remains 

attached

Option A

Load 1: 5g quasi-static

Pass/fail: No plastic deformation

Load 2: Dynamic crash pulse, calculated in scenario

Pass/fail: Average deceleration ≤5g,

Peak deceleration ≤10g

Option B

Load: Dynamic crash pulse, calculated in scenario

Pass/fail: Truck remains attached

Lateral Load: 250 kip

Pass/fail: Remains 

attached

Load: 1g quasi-static

Pass/fail: No plastic deformation

Vertical Load: 2g static

Pass/fail: Remains 

attached

Load: 3g quasi-static

Pass/fail: No plastic deformation

Longitudinal

Under some circumstances, the individual criteria may be more stringent than the CFR 

requirements; in other circumstances, the individual CFR requirements may be more stringent.

For equipment such as Metrolink‘s current multilevel equipment and most of Metra‘s gallerystyle equipment, the criteria are intended to be more stringent. For equipment such as Amtrak‘s

Amfleet I and II cars, the CFR is more stringent. If the truck attachment is resilient, as it is for 

the Amfleet equipment, then the criteria are less stringent. If the truck attachment is initially soft 

with a hard stop, as it is for the Metrolink equipment, then the criteria are more stringent.

Lateral

The CFR is more stringent than the criteria. The criteria would result in truck attachment failure 

for loads between 20 and 40 kip for trucks weighing between 10 and 20 kip, with the assumption 

that the failure load is twice the load required for plastic deformation. The rationale for using a 

lower lateral load comes from accident investigations. Damage observed in these investigations 

indicates that the longitudinal loads on the truck during an accident are greater than the lateral 

loads. The truck failures that have been observed are primarily because of the longitudinal loads.

In some accidents, lateral load has contributed to attachment failure, but the damage suggests 

that its contribution is small compared to the longitudinal load.

Vertical

The criteria are more stringent than the CFR, requiring a load somewhere between 60 and 

120 kip for truck attachment failure.

Overall, the criteria for truck attachment are intended to be equivalent to the current regulation; 

some aspects are more stringent, and other aspects are less stringent than the current CFR 
40

requirement. The longitudinal criteria are expected to be more effective than the current 

regulation, the lateral criteria are expected to be less effective, and the vertical criteria are 

expected to be the same. The sum is expected to be at least the same, if not even a bit better, as 

most truck attachment failures occur primarily as a result of an excessive longitudinal load.

2.3.2 Car-Level

There are six car-level criteria:

 OVI

 End frame strength, cab end

 End frame strength, noncab end

 Side strength

 Roof strength

 Fluid entry inhibition

Occupied Vehicle Integrity

Preservation of occupied volume is essential to the crashworthiness of any rail car. The 

regulation and standards governing this aspect of the car include a strength-based design 

requirement for the car to support a quasi-static load of 800,000 lb along the line of draft without 

experiencing permanent deformation. Because conventional passenger rail cars carry both the 

service and collision longitudinal loads along the line of draft, the regulations require a minimum 

elastic resistance to a load along that load path. The load specified in the regulations is readily 

applied to cars with a traditional buff stop arrangement and an apparent line of draft. However, 

application of this load presents some difficulty for vehicles without conventional buff stops, a 

difficult-to-define line of draft, or a collision load path that differs from the service load path.

A strength-based approach was used in developing the options in the OVI criteria for 

alternatively designed equipment. Car-level OVI requirements are designed to work in concert 

with the train-level scenario to ensure that the space for the passengers and crew is preserved in 

moderately severe accident conditions. In addition, as two of the options allow permanent 

deformation to occur, it is anticipated that analysis will be used to demonstrate that a car meets a 

particular option. Analysis requires proper validation through nondestructive testing of the 

vehicle undergoing evaluation. Testing and analysis procedures are discussed in detail in 

Section 4 – Procedures.

To recognize the variety of designs currently operating in other parts of the world (e.g., highfloor, partial-low floor, coupled, articulated, EMU, DMU, multilevel, etc.), the OVI criteria 

options were designed to be readily applied to a variety of designs. Rather than placing the load 

along the line of draft, the options all recommend that the load be placed along the collision load 

path. This load placement ensures that the OVI is evaluated in a manner based on the way it will 

be loaded during a collision. The three options were developed to help ensure a comparable level 

of OVI among vehicles meeting any one option. A design needs to demonstrate that it meets at 

least one of the three options, or it otherwise must comply with the regulation itself.

Option A requires a carbody to support a quasi-static load of 800,000 lb applied along the 

collision load path without permanent deformation of the body structure. This option is most 
41

closely related to the U.S. requirement of 800,000 lb applied along the line of draft. However, as 

alternatively designed equipment may feature a nonconventional line of draft load path, 

particularly for collision loads, the load is applied to the collision load path as determined by the 

manufacturer. The locations where high longitudinal loads can be applied to the carbody 

structure are determined as part of the design development. Because the applied load is the same 

magnitude as the load required by the existing regulation, the pass/fail criterion of no permanent 

deformation throughout the body structure is the same as in the regulation.

Option B requires a carbody to support a quasi-static load of 1,000,000 lb applied along the 

collision load path with a limited amount of permanent deformation. This load is 25 percent 

higher than the 800,000-pound load required by the regulation. Because the load magnitude has 

been increased, the pass/fail criterion allows some permanent deformation under this loading 

condition. Permanent deformation is limited to 5 percent plastic equivalent strain throughout the 

occupied volume. Additionally, no 15-foot section of occupied volume may decrease in length 

by more than 1 percent. Values chosen for ―limited permanent deformation‖ were developed 

based on analyses performed on conventional and alternatively designed passenger equipment 

under the given load.

Option C requires a carbody to support a quasi-static load of 1,200,000 lb applied along the 

collision load path without crippling the body structure. Crippling of the body structure has been 

defined as the largest load the occupied volume can support. This value is indicated by the peak 

on a load-displacement characteristic. An example load-displacement characteristic, with 

crippling load indicated, is shown in Figure 33.

Figure 33. Example Load-Displacement Characteristic Indicating Crippling Load

This load is 50 percent larger than the 800,000-pound load required by the regulation. A large 

load value was chosen to provide a safety margin over the minimum elastic load met by Tier Icompliant equipment. The load magnitude was chosen based on analysis of the capabilities of 

conventional and alternatively designed equipment.

0

250

500

750

1000

1250

1500

0 0.5 1 1.5 2 2.5 3 3.5

Load (kips)

Displacement (in)

Load-Displacement

Crippling 

Load
42

End Frame Strength, Cab-End

The end frame strength requirements consist of multiple regulations. These regulations include 

requirements for the strength of collision posts (49 CFR 238.211) and corner posts (49 CFR 

238.213). The intent of the end frame strength requirements on the cab end is to prevent 

occupied volume intrusion from objects impacting the end of the car above the level of the 

underframe [38]. Figure 34 shows the lead MU cab car from a collision in Portage, IN. The MU 

train struck a truck transporting steel coils at a highway-rail grade crossing. One coil penetrated 

the occupied volume through the end frame, resulting in three fatalities.

Figure 34. Lead Cab Car after Striking Truck at Highway-Rail Grade Crossing (Portage, 

IN – 1998)

An option is presented to allow vehicles without conventional corner and/or collision posts to 

demonstrate an equivalent level of intrusion prevention. The specified option applies Appendix F 

of 49 CFR Part 238 to both the corner and collision posts, respectively. Appendix F includes 

performance requirements for dynamic testing of the corner and collision post structures as well 

as target levels of energy absorption for each post. The requirements of Appendix F are 

applicable to a variety of end-structure geometries and not just those resembling conventional 

end frame designs. A combination of testing and analysis may be used to demonstrate that a 

design meets the requirements of Appendix F, with any difficult-to-analyze or critical-toperformance components being tested.
43

End Frame Strength, Noncab-End

Noncab end frame strength is also covered by multiple regulations. There are regulations for 

corner posts of specified design (§ 238.213) and collision posts of specified design (§ 238.211).

As an option to the collision post requirements, a vehicle design with pushback couplers and 

interlocking anticlimbers capable of preventing coupled vehicles from climbing and overriding 

each other does not require collision posts at the interior coupling location. The collision posts on 

these noncab ends serve principally to prevent intrusion by the coupled car in case of override. If 

this mode of deformation has been eliminated through pushback couplers and anti-climbers, 

collision posts are not required.

Corner posts serve a somewhat different function from collision posts on noncab ends. Although 

they can act along with collision posts to prevent an overriding car from compromising occupied 

volume, corner posts also serve to prevent loss of occupied volume when struck by another train 

or a wayside obstruction. In particular, corner posts are effective at preventing intrusion by an 

object dragging along the side of the train consist. Figure 35 shows a postaccident photo from a 

1997 accident in Gary, IN, in which the locomotive-hauled passenger consist struck a truck at a 

grade crossing. The truck damaged the side of the leading locomotive and the leading corner of 

the first trailing coach.

Figure 35. Corner and Side Damage to Trailing Coach (Gary, IN – 1997)

The option for corner posts requires some structure at the corners of the occupied volume 

capable of resisting intrusion. However, this structure does not have to be a post, per se. The 

design loads that are applied to the corner post (as part of the regulation) on a Tier I-compliant 
44

design can be applied to the corner structure on an alternatively designed vehicle. The structure 

must be capable of meeting the requirements of the design loads specified in the regulation. A 

combination of testing and analysis may be used to demonstrate that a design meets the 

requirements, with any difficult-to-analyze or critical-to-performance components being tested.

Side Strength

The side strength regulations are intended to ―help to resist penetration of the passenger car‘s 

side structure by an outside object‖ [23]. Localized penetration can be the result of a highwayrail grade crossing collision in which a highway vehicle impacts the side of the train or of a 

raking collision between two trains on adjacent tracks. The side structure stiffness requirement 

also offers resistance to global crush during a derailment in which a passenger car may end up on 

its side. Figure 36 shows damage to the side structure of an MU locomotive that had struck 

construction equipment that was fouling the right-of-way. The construction equipment was 

initially struck by the corner post of the MU locomotive but caused damage along the length of 

the sidewall. This accident occurred in Hewlett, NY, in 2001.

Figure 36. MU Side Structure Damage after Striking Construction Equipment (Hewlett, 

NY – 2001)

The side strength criteria do not specify an option to the regulation. The regulation consists of 

design requirements prescribing a minimum section modulus for the side structure about a 

transverse axis and a minimum section modulus about a vertical axis. The regulation also 

prescribes a minimum thickness of material, which may be used for the side sheathing with an 

allowance for thinner material of higher strength.
45

Rollover Strength

The rollover strength requirements are intended to prevent intrusion into the occupied volume in 

the event of a rollover in which the vehicle is being supported by the roof structure or the side 

structure [23]. The roof strength criteria do not specify an option to the regulation. The 

regulation consists of two performance requirements to help ensure adequate strength in the 

event of vehicle rollover. The first requirement is for the side structure to support the weight of 

the vehicle without exceeding one-half its yield or critical buckling stress, whichever is less. The 

second requirement is for the roof structure to support the weight of the overturned car with 

damage limited to the roof sheathing and framing. Additionally, throughout the other structural 

members of the occupied volume, the stress may not exceed one-half the yield or critical 

buckling stress, whichever is less. Figure 37 shows a derailed car supported on its roof and side 

structure from a derailment that occurred in Nodaway, IA, in 2001.

Figure 37. Derailed Car Supported by its Roof and Side Structures (Nodaway, IA – 2001)

Fluid Entry Inhibition

This requirement applies specifically to the lead vehicle in the train. The purpose of the 

requirement is to protect the occupied volume of the cab, particularly against fluid entry resulting 

from a grade-crossing collision [23]. In grade crossing collisions between cab car- or MU 
46

locomotive-led trains and highway vehicles transporting bulk liquid commodities, there is a 

potential for the fluid to enter the occupied volume of the car.

The fluid entry inhibition criteria do not specify an option to the regulation. The regulation 

allows for some variation in design and materials for the end structure of the car, so long as the 

overall combination of material thickness and strength is equivalent to the specified value. See 

75 FR 1180, 1217 (Jan. 8, 2010).

2.3.3 Interior Occupant Protection

There are two occupant protection criteria:

 Interior fixture attachment

 Occupant protection features

Interior Fixture Attachment

The interior fixture attachment requirements are intended to help ensure that fixtures mounted to 

the walls, ceiling, or floor in occupied areas do not detach during an accident and become 

projectiles that could impact occupants. Furthermore, fixtures that remain attached may assist in 

compartmentalizing occupants during an accident, preventing tertiary impacts with other 

occupants or objects. There are no specified options for complying with the interior fixture 

attachment criteria. The Federal regulations in 49 CFR 238.233 apply to all Tier I equipment, 

regardless of design.

The following FRA regulations related to interior fitting attachment may also apply:

– § 229.45 – General condition

– § 229.119 – Cabs, floors, and passageways

– § 229.135 – Event recorders

– § 238.115 – Emergency lighting

– § 238.117 – Protection against personal injury

– § 238.121 – Emergency communication

– § 238.221 – Glazing

– § 238.223 – Locomotive fuel tanks

– § 238.225 – Electrical system

– § 238.307 – Periodic mechanical inspection of passenger cars and unpowered vehicles 

used in passenger trains

The following APTA standards related to interior fitting attachment may also apply:

– APTA SS-C&S-006-98, Rev. 1 – Standard for Attachment Strength of Interior Fittings 

for Passenger Railroad Equipment

– APTA SS-C&S-011-99 – Standard for Cab Crew Seating Design and Performance

– APTA SS-C&S-016-99 Rev. 2 – Standard for Passenger Seats in Passenger Rail Cars

– APTA SS-C&S-034-99, Rev. 2 – Standard for the Design and Construction of Passenger 

Railroad Rolling Stock
47

These APTA standards constitute the industry standards for interior fitting attachment strength,

and FRA looks to these standards as complementary to FRA‘s requirements. See 64 FR 25540, 

25541 (May 12, 1999). APTA‘s standards on interior fitting attachment strength are generally 

more specific than FRA‘s requirements.

Occupant Protection Features

The occupant protection features criteria are intended to provide minimum seat requirements 

related to seat attachment strength, human injury criteria associated with dynamic seat testing, 

and flame and smoke standards. These criteria are specified in APTA SS-C&S-016-99, Rev. 2 –

Standard for Passenger Seats in Passenger Rail Cars, and APTA SS-C&S-011-99 – Standard for 

Cab Crew Seating Design and Performance. These safety standards were originated in 1999, and 

they overlay FRA‘s requirements for seats in 49 CFR § 238.233 and for fire safety in § 238.103. 

They are necessary to help ensure that seats remain attached during an accident, that the forces 

and accelerations experienced by an occupant are within human tolerance levels, and that the 

materials used to fabricate the seats do not pose significant smoke or fire hazards.

EN has limited requirements for occupant protection. Generally, EN requires that survival space 

must be preserved under specific collision conditions, but there are no specific requirements to

minimize injury associated with secondary impacts between the occupant and the seat.

As seats in new conventional equipment must comply with the requirements of these safety 

standards, so too must the seats used in alternatively designed equipment comply with safety 

standards. There are no options specified for complying with the occupant protection features 

criteria.
48

3. Criteria

3.1 Requirement: Collision with Conventional Equipment

Although there is no analog to this collision scenario presently included in the CFR for Tier I 

passenger equipment, the combination of a dynamic collision evaluation (Section 3.1) and a 

quasi-static OVI evaluation (Section 3.2) helps provide assurance of sufficient resistance to loss 

of occupied volume. If a waiver of the requirements of § 238.203 is sought based on the 

guidance provided in this document, it is expected that the vehicle in question will be shown to 

meet the criteria contained within both Section 3.1 and Section 3.2 of this document.

The evaluation collision scenario is defined as follows:

Figure 38. Collision Scenario

Equipment

 Initially Moving Train: The train is made up of alternatively designed equipment at AW0 

ready-to-run condition. The length of the consist reflects its planned operational use. If 

train configurations of varying consist length are intended for use, the configurations

having the longest and shortest consist lengths shall be evaluated. If the train is intended 

for push-pull service, then both the cab car-led and conventional locomotive-led 

configurations shall be evaluated separately.

 Initially Standing Train: This train is a conventional locomotive-led passenger train. The 

train consists of one leading, conventional locomotive weighing 260,000 lb and five 

conventional passenger cars each weighing 95,000 lb. Details on the locomotive 

geometry and conventional passenger cars can be found in Appendix C. Locomotive 

and Passenger Car Input Data.

Initial Conditions

 Tangent, Level Track.

 Moving Train Impact Speed:

o A) 20 mph, if cab car- or MU locomotive-led train, or

o B) 25 mph, if conventional locomotive-led train

 Coupler knuckles are closed for each colliding vehicle.

 Moving and standing train are not braked.

 The standing train has only 1 degree of freedom (longitudinal direction).

Results

 Preserve interior spaces occupied by passengers.

- The occupied volume for the passengers shall have no more than 10 in of 

longitudinal, permanent deformation; or
49

- Global vehicle shortening shall be no more than 1 percent over any 15 ft of the 

occupied volume.

 Maintain safe secondary impact environment.

- Compare the secondary impact velocity (SIV) curve, calculated at the CG of each 

car/locomotive, to the SIV curve associated with the 8g, 250-millisecond 

triangular crash pulse.

 Preserve interior space for engineer.

- Each seat in the operating compartment shall have a survival space where there is 

no intrusion after the collision scenario;

- The survival space shall be a minimum of 12 in from the edge of the seat;

- Flip-down seats will not be used;

- There shall be a clear exit path for the occupants after the collision scenario;

- The vertical height of the compartment (floor to ceiling) shall not be reduced by 

more than 20 percent after the collision scenarios; and

- The operating console shall not move closer to the engineer‘s seat after the 

collision scenario. 

Figure 39 shows an overhead view of the engineer‘s seat. The 12-inch-wide minimum survival 

space on each side of the seat is indicated in this figure. No intrusion is permitted to occur within 

the boundaries of the dashed line during the collision scenario.

Figure 39. Engineer’s Seat with Survival Space Indicated
50

3.2 Requirement: Occupied Volume Integrity

The combination of a dynamic collision evaluation (Section 3.1) and a quasi-static OVI

evaluation (Section 3.2) helps provide assurance of sufficient resistance to loss of occupied 

volume. If a waiver of the requirements of § 238.203 is sought based on the guidance provided in 

this document, it is expected that the vehicle in question will be shown to meet the criteria 

contained within both Section 3.1 and Section 3.2 of this document.

Title 49 CFR Requirement

§ 238.203. Static end strength.

This subpart is excerpted in Appendix B. Selected CFR References.

******************************************************************************

Options

The following options are provided as alternatives to the stated regulation to demonstrate 

sufficient OVI. The equipment must comply with either the regulation or at least one of these 

alternatives.

Option A

Passenger equipment shall resist a minimum quasi-static end load of 800,000 lb applied on the 

collision load path without permanent deformation of the occupied volume.

Option B

Passenger equipment shall resist a minimum quasi-static end load of 1,000,000 lb applied on the 

collision load path with limited permanent deformation of the occupied volume. This load shall 

be supported without exceeding either of the following two conditions:

- Local plastic strains of 5 percent; or

- Vehicle shortening of 1 percent over any 15 ft of the occupied volume.

Option C

Passenger equipment shall resist a minimum quasi-static end load of 1,200,000 lb applied on the 

collision load path without crippling the body structure. Crippling of the body structure is 

defined as the maximum point on the load-displacement characteristic.
51

3.3 Requirement: Colliding Equipment Override

Title 49 CFR Requirement

§ 238.205. Anticlimbing mechanism.

This subpart is excerpted in Appendix B. Selected CFR References.

******************************************************************************

Option

Given the scenario described in Section 3.1, anticlimb features shall be demonstrated for each of

the following sets of initial conditions:

1) All cars in the moving and standing consists are positioned at their nominal running 

heights.

2) The interface of the colliding equipment is perturbed laterally and vertically by 3 in.

The pass/fail criteria are as follows:

- The relative difference in elevation between the underframes of the colliding and 

connected equipment shall not change by more than 4 in; and

- The tread of any wheel of the alternatively designed equipment shall not rise 

above the top of rail more than 4 in.
52

3.4 Requirement: Connected Equipment Override

Title 49 CFR Requirement

§ 238.205. Anticlimbing mechanism.

§ 238.207. Link between coupling mechanism and carbody.

These subparts are excerpted in Appendix B. Selected CFR References.

******************************************************************************

Option

Given the scenario described in Section 3.1, anticlimb features shall be demonstrated for each of 

the following sets of initial conditions:

1) All cars in the moving and standing consists are positioned at their nominal running 

heights.

2) The first car-to-car interface of the initially moving consist is perturbed laterally and 

vertically by 2 in.

Figure 40. Location of Offsets in Moving Consist

Figure 41. Illustration of Offsets for Coupled Cars

2 inch vertical and 

lateral offsets
53

Figure 42. Illustration of Offsets for Articulated Cars

The pass/fail criteria are as follows:

 The relative difference in elevation between the underframes of the connected equipment 

shall not change by more than 4 in; and

 The tread of any wheel of the alternatively designed equipment shall not rise above the 

top of rail more than 4 in.

2 inch lateral 

offset Track Centerline

Articulation Centerline

2 inch vertical 

offset Nominal Floor Height
54

3.5 Requirement: Fluid Entry Inhibition

Title 49 CFR Requirement

§ 238.209. Forward end structure of locomotives, including cab cars and MU locomotives.

This subpart is excerpted in Appendix B. Selected CFR References.

******************************************************************************

Option

None specified. FRA makes clear that aluminum and other material—not steel plate alone—can 

be used to keep fluids and debris from entering the ends of the car, as required by § 238.209. 

However, the material must have strength at least equivalent to that for the steel plate specified.
55

3.6 Requirement: End Structure Integrity of Cab End

Title 49 CFR Requirement

§ 238.211. Collision posts.

§ 238.213. Corner posts.

These subparts are excerpted in Appendix B. Selected CFR References.

******************************************************************************

Option

The option presented below allows the use of Appendix F to Part 238 to demonstrate end 

structure integrity for the cab end of the car. In Appendix F, the phrases ―collision post‖ and 

―corner post‖ are used to describe the end structure of the car. For purposes of this option, this 

wording can be thought of as referring to any structure at the specified locations, whether that 

structure is or is not a post.

Title 49 CFR

§ 238.209. Forward end structure of locomotives, including cab cars and MU locomotives

Appendix F to Part 238—Alternative Dynamic Performance Requirements for Front End 

Structures of Cab Cars and MU Locomotives

This subpart is excerpted in Appendix B. Selected CFR References.
56

3.7 Requirement: End Structure Integrity of Noncab End

Title 49 CFR Requirement

§ 238.211. Collision posts.

§ 238.213. Corner posts.

These subparts are excerpted in Appendix B. Selected CFR References.

*****************************************************************************

Collision Post Option

Collision posts are not required for equipment with pushback couplers and interlocking 

anticlimbers, provided that the intercar connection is capable of preventing disengagement and 

telescoping to the same extent as equipment satisfying the anticlimbing and collision post 

requirements contained in 49 CFR Part 238. (See Option for § 238.205. Anticlimbing 

mechanism, for description of criteria for determining whether connection is capable of 

preventing disengagement and telescoping.)

Corner Post Option

(a) Each passenger car shall have at each end of the car, placed ahead of the occupied volume, 

two side structures capable of resisting:

(1) A 150,000-pound horizontal force applied at floor height without failure;

(2) A 20,000-pound horizontal force applied at ceiling height without failure; and

(3) A 30,000-pound horizontal force applied at a point 18 in above the top of the floor without 

permanent deformation.

(b) For purposes of this section, the orientation of the applied horizontal forces shall range from 

longitudinal inward to transverse inward.
57

3.8 Requirement: Roof Integrity

Title 49 CFR Requirement

§ 238.215. Rollover strength.

This subpart is excerpted in Appendix B. Selected CFR References.

*****************************************************************************

Option

None specified.
58

3.9 Requirement: Side Structure Integrity

Title 49 CFR Requirement

§ 238.217. Side structure.

This subpart is excerpted in Appendix B. Selected CFR References.

******************************************************************************

Option

None specified.
59

3.10 Requirement: Truck Attachment

Title 49 CFR Requirement

§ 238.219. Truck-to-carbody attachment.

This subpart is excerpted in Appendix B. Selected CFR References.

******************************************************************************

Options

The following options are provided as alternatives to the stated regulation to demonstrate 

sufficient truck-to-carbody attachment. The equipment must comply with either the regulation or 

at least one of these alternatives to demonstrate compliance with the criteria stated in this 

document.

Option A

Passenger equipment shall have a truck-to-carbody attachment with strength sufficient to resist 

without yield the following individually applied quasi-static loads on the mass of the truck at its 

CG: 3g vertically; 5g longitudinally, along with the resulting vertical reaction to this load; and 1g 

laterally, along with the resulting vertical reaction to this load. For the purposes of this option, 

the mass of the truck includes axles, wheels, bearings, the truck-mounted brake system, 

suspension system components, and any other component attached to the truck by design.

In addition, for the nominal initial condition given in the scenario described in Section 3.1:

 The average longitudinal deceleration of the car during the impact shall not exceed 5g;

and

 The peak longitudinal deceleration of the truck shall not exceed 10g.

******************************************************************************

Option B

Passenger equipment shall have a truck-to-carbody attachment with strength sufficient to resist 

without yield the following individually applied quasi-static loads on the mass of the truck, at its 

CG: 3g vertically and 1g laterally, along with the resulting vertical reaction to these loads. For

the purposes of this option, the mass of the truck includes axles, wheels, bearings, the truckmounted brake system, suspension system components, and any other component attached to the 

truck by design.

In addition, the truck shall remain attached during the scenario described in Section 3.1.

******************************************************************************
60

3.11 Requirement: Interior Fixture Attachment

Relevant definitions excerpted from 49 CFR 238.5:

Interior fitting means any component in the passenger compartment which is mounted to the 

floor, ceiling, sidewalls, or end walls and projects into the passenger compartment more than 

25 mm (1 in) from the surface or surfaces to which it is mounted. Interior fittings do not include 

side and end walls, floors, door pockets, or ceiling lining materials, for example.

Passenger compartment means an area of a passenger car that consists of a seating area and any 

vestibule that is connected to the seating area by an open passageway.

Title 49 CFR Requirement

§ 238.233. Interior fittings and surfaces.

For guidance on the application of § 238.233, which is excerpted in Appendix B. Selected CFR 

References, see the PowerPoint document, FRA Guidance on Interior Fitting Attachment 

Strength.

******************************************************************************

Included by reference:

APTA SS-C&S-006-98, Rev. 1,

Standard for Attachment Strength of Interior Fittings for Passenger Railroad Equipment

APTA SS-C&S-034-99, Rev. 2,

Standard for the Design and Construction of Passenger Railroad Rolling Stock

******************************************************************************

Option

None specified.
61

3.12 Requirement: Occupant Protection Features

Included by reference:

APTA SS-C&S-016-99, Rev. 2

Standard for Row-to-Row Seating in Commuter Rail Cars

APTA SS-C&S-011-99

Standard for Cab Crew Seating Design and Performance
62

4. Example Procedures

4.1 Introduction

This section includes examples of procedures that may be used to evaluate equipment designs 

using the criteria described in Section 3 – Criteria. These procedures are examples of one way 

of applying the criteria; however, there may be other ways of applying the criteria. Example 

procedures are provided for those criteria with an option specified. Entities submitting waiver 

requests may select any engineering-based procedure that they find appropriate. An overview of 

the procedure used by the submitting entity should be included in the waiver request. The 

purpose of these examples is to show that the criteria are practical and can be applied using 

modern engineering techniques.
63

4.2 Guidance Summary

Table 3. Guidance Summary for Criteria and Evaluation

Requirement Summary of Load Case Summary of Criteria

Collision with 

conventional 

equipment

Alternatively designed train in collision with 

conventional locomotive-led train:

(a) 20 mph, cab car- or MU locomotive-led; or

(b) 25 mph, conventional locomotive-led

Preserve occupied volume for passengers

Preserve survival space in operating cab

OVI

On the intended collision load path:

(a) 800 kip

(b) 1,000 kip

(c) 1,200 kip

(a) No permanent deformation

(b) Limited permanent deformation

(c) Without crippling

Colliding equipment 

override

Alternatively designed equipment collision with 

conventional locomotive:

(a) all equipment aligned; or 

(b) consists offset 3 in vertical and laterally

No override and

wheel lift minimized

Connected 

equipment override

Alternatively-designed equipment in collision with 

conventional locomotive, with 2-inch vertical/2-inch 

lateral offsets of first car-to-car connection

No override and

wheel lift minimized

Fluid entry 

inhibition Based on design review

(a) Equivalent to 1/2-inch steel plate with 25,000 

psi yield strength;

(b) Designed to inhibit the entry of fluids into the 

occupied area; and

(c) Affixed to structural members

End structure 

integrity of cab end

(a) Absorb minimum of 135 ft-kip of energy for 

impact offset 19 in from longitudinal centerline

(b) Absorb minimum 120 ft-kip of energy for impact 

aligned with sidewall

No more than 10 in of longitudinal, permanent 

deformation

End (corner) 

structure integrity of 

noncab end

(a) 150 kip at floor height

(b) 30 kip 18 in above floor

(c) 20 kip at ceiling height

(a) Without failure

(b) Without permanent deformation

(c) Without failure

Roof integrity Equipment upside down, supported by roof (a) No occupied volume intrusion; and

(b) No more than 1/2 yield or buckling

Side structure 

integrity

Design requirements on sidewall stiffness and 

material properties

Vertical modulus (in3) > 0.3 × L

Horizontal modulus (in3) > 0.2 × L

Truck attachment

Scenario 3.1 plus either:

(a) 3g vertical, 1g lateral, 5g longitudinal; or

(b) 3g vertical, 1g lateral

Static analyses: Without yielding; and

(a) Scenario 3.1: Avg. acc. < 5g and

Max. acc. < 10g; or

(b) Scenario 3.1: Trucks remain attached

Interior fixture 

attachment

Fixtures: 8/4/4g Longitudinal/lateral/vertical quasistatic load; and

Seats: 8g longitudinal dynamic pulse

Fixtures and seats remain attached

Seats

8g sled test with instrumented HIII ATDs per Rev. 2 

of APTA-SS-C&S-016-99

Seats must meet requirements in Rev. 2 of 

APTA-SS-C&S-016-99, including injury criteria

Note: Table for use as a summary only for the requirements noted.
64

4.3 Requirement: Collision with Conventional Equipment

This section includes the criteria and procedures for evaluating alternatively designed equipment 

for a collision with conventional equipment. The procedures and results in this section show the 

types of analyses and results that demonstrate compliance with the criteria. Other procedures 

may be followed in demonstrating compliance.

4.3.1 Criteria

The evaluation collision scenario is defined as follows:

Figure 43. Collision Scenario

Equipment

 Initially Moving Train: The train is made up of alternatively designed equipment at AW0 

ready-to-run condition. The length of the consist reflects its planned operational use. If 

train configurations of varying consist length are intended for use, the configurations

having the longest and shortest consist lengths shall be evaluated. If the train is intended 

for push-pull service, then both the cab car-led and conventional locomotive-led 

configurations shall be evaluated separately.

 Initially Standing Train: This train is a conventional locomotive-led passenger train. The 

train consists of one leading, conventional locomotive weighing 260,000 lb and five 

conventional passenger cars each weighing 95,000 lb. Details on the locomotive 

geometry and conventional passenger cars can be found in Appendix C. Locomotive 

and Passenger Car Input Data.

Initial Conditions

 Tangent, Level Track.

 Moving Train Impact Speed:

o A) 20 mph, if cab car- or MU locomotive-led train, or

o B) 25 mph, if conventional locomotive-led train

 Coupler knuckles are closed for each colliding vehicle.

 Moving and standing train are not braked.

 The standing train has only 1 degree of freedom (longitudinal direction).

Results

 Preserve interior spaces occupied by passengers.

- The occupied volume for the passengers shall have no more than 10 in of 

longitudinal, permanent deformation; or

- Global vehicle shortening shall be no more than 1 percent over any 15 ft of the 

occupied volume.

 Maintain safe secondary impact environment.
65

- Compare the secondary impact velocity (SIV) curve, calculated at the CG of each 

car/locomotive, to the SIV curve associated with the 8g, 250-millisecond 

triangular crash pulse.

 Preserve interior space for engineer.

- Each seat in the operating compartment shall have a survival space where there is 

no intrusion after the collision scenario;

- The survival space shall be a minimum of 12 in from the edge of the seat;

- Flip down seats will not be utilized;

- There shall be a clear exit path for the occupants after the collision scenario;

- The vertical height of the compartment (floor to ceiling) shall not be reduced by 

more than 20 percent after the collision scenarios; and

- The operating console shall not move closer to the engineer‘s seat after the 

collision scenario. 

Figure 44 shows an overhead view of the engineer‘s seat. The 12-inch-wide minimum survival 

space on each side of the seat is indicated in this figure. No intrusion is permitted to occur within 

the boundaries of the dashed line during the collision scenario.

Figure 44. Engineer’s Seat with Survival Space Indicated

4.3.2 Example Procedures

This section describes the information required for conducting the collision dynamics analyses.

Approaches for conducting such analyses include lumped-parameter analysis and finite element 

analysis, as well as hybrid approaches. In lumped-parameter analysis, each car is represented by 

a small number of masses and a small number of force-crush characteristics. In the extreme, each 

car can be represented by a single mass with a single force-crush characteristic between masses 

(cars). Generally, in a lumped-parameter model, the degrees of freedom available to the masses 

are restricted, with the extreme being a single degree of freedom model. In finite element 

analysis, structures are meshed into a large number of elements. Each element has a mass and 

stiffness connecting it to adjacent elements. A finite element model of a rail passenger carbody 
66

may have more than 500,000 elements, each associated with a mass. In the extreme, all of the 

structural elements of all of the cars—carbodies, trucks, couplers, etc. —are meshed and 

represented by finite elements that are able to represent three-dimensional motion of the vehicles.

In a hybrid approach, some of the structural elements of the cars that make up the train are 

modeled with finite elements, and some of the structural elements are represented as lumped 

masses and force-crush characteristics. Two examples are described in this section, one example 

with lumped-parameter analysis and the other example with hybrid analysis, using finite 

elements to model the colliding equipment and lumped-parameters to model the trailing 

equipment. 

All three approaches—lumped parameter, finite element, and hybrid—can be used to develop the 

required information. The required result that the occupied volume for the passengers shall have 

no more than 10 in of longitudinal, permanent deformation is more readily applied to the results 

of a lumped-parameter analysis, whereas the alternative requirement that results that the global 

vehicle shortening shall be no more than 1 percent over any 15 ft of the occupied volume is more 

readily applied to the results from a finite element analysis. Because only one of these two 

results is necessary, the one that is more readily applied may be selected.

As shown in Figure 45, car crush results are key inputs to the train collision dynamics analyses.

Force-crush characteristics from a separate car crush analysis define the car ends in a lumpedparameter model. In addition, the mode of deformation assumed in developing train collision 

dynamics must be consistent with the mode of deformation observed in the car crush analyses.

Force-crush characteristics are computed internally with finite element analysis.

Figure 45. Flowchart of Evaluation Procedure

Figure 46 is a graphical illustration of the relationship between the car crush analysis (typically 

performed with the finite element method), the mode of deformation, and the lumped-parameter 

train collision dynamics analyses.

Acceleration

Velocity

Displacement

Occupant Volume 

Crushed

Collision 

Dynamics 

Evaluation

Force-crush

Characteristic

Mode of Crush

Collision Scenario

Car Crush 

Evaluation
67

Figure 46. Relationship between Car/Locomotive Crush Evaluation and Train Collision 

Dynamics Evaluation

Note that for valid evaluations, a high level of assurance is needed that car crush analytical 

results are consistent with the train collision dynamics. This can be demonstrated with 

destructive component tests or nondestructive OVI tests, backed by plastic analysis.

Car Crush Evaluation

A car crush analysis is used to produce the force-crush characteristics and the modes of 

deformation of each car end. Figure 47 shows the required input and output for a crush 

evaluation. A typical car crush analysis may be performed using a validated finite element model 

of the car of interest. Example procedures for validating a finite element model using structural 

test data are provided in Validation Procedures.

Evaluate Car Crush Develop Force-crush

Assure Mode

Crush Force

Moving Consist Stationary Consist

Loco Coach 1 Coach 2 Coach 3 Coach 4 Cab Lead Cab Loco Coach 4 Coach 3 Coach 2 Coach 1

V0

Input to Collision 

Dynamics Evaluation
68

Figure 47. Key Inputs and Outputs for Car Crush Analysis

 Key Output

- Force-crush characteristic

 Key Features Meet Targets (e.g., Pushback Coupler (PBC) Trigger Load, 

Crush Loads)

 Robust OVI to Support Component Loads

- Mode of Crush

 Sequence of Events Meets Target

 Limited Vertical Displacement for Full Range of Crush

 Procedures

- Nonlinear Finite Element Modeling

- Component Testing

- Nondestructive Occupied Volume Testing

Train-Level Evaluation

A collision dynamics analysis is used to demonstrate compliance with the scenario requirements.

Figure 48 shows the development of a collision dynamics evaluation.

Figure 48. Key Inputs and Outputs for Collision Dynamics Evaluation

Geometry

Materials

Loads,

Boundary 

Conditions,

Initial Conditions

Crush

Evaluation

Modes of

Deformation

Force-crush

Characteristics

INPUT OUTPUT

Train

Collision

Dynamics

Evaluation

Collision 

Scenarios

Force/Crush

Behavior

Acceleration

Velocity

Displacement

Car Crush
69

Example Evaluation A: Lumped-Parameter Analysis

Figure 49 is a schematic of a lumped-mass model for the given collision scenario. The moving 

consist should include the appropriate number and configuration of vehicles for the equipment 

being evaluated. In the one-dimensional lumped mass analyses, motion is constrained to 

translation only. Each vehicle may be considered a single, rigid mass, and car ends are 

characterized by deformable springs with prescribed force-deflection characteristics.

Figure 49. Schematic of a Lumped-Parameter Model for a Train-to-Train Collision 

Scenario

Example Evaluation B: Hybrid Finite Element Analysis

Figure 50 is a schematic of a finite element model for the given collision scenario. In this 

evaluation, the collision scenario is simulated using three-dimensional finite element analysis at 

the collision interface with one-dimensional lumped-mass simplification of all trailing cars. The 

moving consist should include the appropriate number and configuration of vehicles for the 

equipment being evaluated. The model includes a full three-dimensional representation of the 

first vehicle in each consist to properly capture the deformation of each vehicle end involved at 

the collision interface. The trailing vehicles in each consist are modeled using one-dimensional 

lumped-mass analyses, where motion is constrained to translation only. Each trailing vehicle 

may be considered a single, rigid mass, and car ends are characterized by deformable springs 

with prescribed force-deflection characteristics.

Figure 50. Schematic of a Finite Element Model for a Train-to-Train Collision Scenario

Table 4 shows key input parameters, for example, equipment designs. Each vehicle end must 

preserve occupied space in accordance with the criteria for the collision scenario (see Section 3 –

Criteria). The point of intrusion for each vehicle end depends on the specific seating 

configuration and layout of occupied space.

Moving Consist Stationary Consist

Loco Coach 1 Coach 2 Coach 3 Coach 4 Cab Lead

Cab Loco Coach 4 Coach 3 Coach 2 Coach 1

V0
70

Table 4. Example of Key Inputs for Collision Dynamics Analysis

Equipment

Example 1:

FRA-Prototype CEM 

Train

Example 2:

Proposed Alternate

Train

Scenario 1: Conventional 

Standing Train

Train Makeup

Cab car, 

4 passenger coaches, and 

conventional locomotive

4 MU consist Conventional locomotive, 4 

passenger coaches, cab car

Speed 20 mph 20 mph Stationary

Vehicle Weights

Cab car = 95 kip

Passenger coach = 95 kip

Locomotive = 260 kip

MU = 95 kip Locomotive = 260 kip

Passenger/cab cars = 95 kip

Level of 

Braking None None None

Figure 51 illustrates another key input to the collision dynamics model, the idealized force-crush 

characteristics for different types of equipment. The top graph illustrates the force-crush 

characteristics for the FRA-prototype CEM equipment (both cab end and noncab end) and the 

second graph illustrates force-crush characteristics, for example, alternatively designed

equipment. The dashed line at the right-hand-end of each characteristic represents the behavior 

of the occupied volume of each vehicle end once its CEM features have been exhausted and its 

OVI compromised.

0.0E+00

5.0E+05

1.0E+06

1.5E+06

2.0E+06

2.5E+06

0.0 1.0 2.0 3.0 4.0 5.0 6.0

Crush (ft) Force (lbf)

Cab End

Non Cab End

0.0E+00

5.0E+05

1.0E+06

1.5E+06

2.0E+06

2.5E+06

0.0 1.0 2.0 3.0 4.0 5.0 6.0

Crush (ft) Force (lbf)

Cab End

Non Cab End

FRA CEM 

Prototype

Proposed 

Alternate

Equipment
71

Figure 51. Example Idealized Force-Crush Characteristics

4.3.3 Example Key Results

This section discusses example results from the car crush analysis and the collision dynamics 

analysis. In general, the car crush results will serve as part of the input to the collision dynamics 

model. The collision dynamics results can then be used to evaluate compliance with the criteria 

for the collision scenario being evaluated.

Car Crush Results

The following section provides an example of developing the idealized force-crush 

characteristics used as inputs to the collision dynamics evaluation. A combination of component 

testing and analysis should be used to support the assumptions and measurements in generating 

the idealized force-crush characteristics. In addition, the requirements of § 238.111—Prerevenue 

service acceptance testing plan—apply to all passenger vehicles, including their structural and 

occupant protection components. Table 5 shows the testing and analysis plan used to develop the 

force-crush characteristic for the FRA-prototype CEM cab-end design. This plan was completed 

to measure the force-crush characteristic of the car end and confirm that it performed as designed

(i.e., confirm the sequence of events, trigger loads, modes of deformation, etc.).
72

Table 5. Example Matrix of Component Testing and Analysis

Figure 52 shows various component tests that were conducted to measure key features of the 

target force-crush characteristic. This test plan included quasi-static and dynamic testing of the 

energy-absorbing components and the initiation mechanisms within the crush zone. The forcecrush behavior measured in the each component test was used in assembling the overall idealized 

force-crush characteristic for the crush zone.

Detailed Analysis

Component

Component 

Level Car Level

Component 

Testing

Primary Energy Absorber Yes Yes Dynamic

Pushback Coupler Yes Yes Dynamic

Sliding Sill/Fixed Sill Yes Yes Static & 

Dynamic

Combined Pushback 

Coupler/Sliding Sill/Fixed Sill Yes Yes Dynamic

Roof Absorber No Yes No

Deformable Anti-climber Yes Yes Sub-component

Detailed Analysis

Component

Component 

Level Car Level

Component 

Testing

Primary Energy Absorber Yes Yes Dynamic

Pushback Coupler Yes Yes Dynamic

Sliding Sill/Fixed Sill Yes Yes Static & 

Dynamic

Combined Pushback 

Coupler/Sliding Sill/Fixed Sill Yes Yes Dynamic

Roof Absorber No Yes No

Deformable Anti-climber Yes Yes Sub-component
73

Figure 52. Verification of Force-Crush Characteristic through a Series of Full-Scale 

Structural Component Tests

The following procedures were used to assemble the force-crush characteristic for the FRAprototype CEM design:

– Component testing

– Nonlinear finite element modeling

A series of component tests demonstrated that criteria were met for the following CEM

components:

– PBC initiation mechanism force within target range

– Pushback coupler energy absorber force-crush behavior and mode within target 

ranges

– Primary energy absorbing mechanism (PEAM) initiation mechanism force within 

target range

– PEAM energy absorber force-crush behavior and mode (average slope) within 

target ranges

A car-to-locomotive finite element model was developed and used to verify that components 

worked together as designed to provide the desired force-crush behavior and modes of 

deformation. Note that, in this example, the locomotive featured deformable geometry. The 

submodel provided in Appendix C. Locomotive and Passenger Car Input Data features rigid 

geometry:

• FE vehicle model development

– F40PHM-based locomotive (Figure 53)

– M1-based cab car with CEM (Figure 54)

Crush Force
74

Figure 53. Rigid and Deformable Geometry of an F40PHM-Based Locomotive

Figure 54. Cab-End Model of FRA-Prototype CEM Cab Car

Striker plate forward of 

end plate arrests 

coupler movement Lugs on side of draft gear 

pocket engage with draft gear

Rigid Sub-assembly 

(blue)

Deformable Subassembly (yellow)

Original M1 Structure

(green)

Underframe & Floor

(blue) Sliding Sill

(yellow)

Pushback 

Coupler

(pink)

Integrated

End Frame

(grey)

Engineer’s

Compartment

(orange)

Partition &

Roof Absorbers

(purple)

Deformable

Anti-climber

(grey)

Interlocking

Anti-climber

(grey)
75

The following analyses were conducted on the cab car to verify that the crush zone met all 

design requirements and performance criteria for ideal and offset collision conditions:

 Static and quasi-static analyses

 Dynamic crush analysis: ideal conditions

 Dynamic crush analysis: offset conditions

Figure 55 shows the initial conditions for a dynamic crush analysis under ideal conditions (i.e., 

all cars in the model are positioned at their nominal running heights). The rear of the cab car was 

fixed in the model, and the conventional locomotive was given an initial velocity of 30 mph.

Figure 55. Cab Car Ideal Dynamic Crush Analysis

Figure 56 shows the kinematic sequence of crush events from the dynamic crush analysis of 

ideal impact conditions. The analysis was executed with sufficient initial kinetic energy to fully 

exhaust the crush zone on the CEM cab car, allowing the full force-crush characteristic to be 

examined.
76

Figure 56. Example Kinematic Sequence of Events from Car-Level Crush Analysis

The force-crush measurement from the crush analysis is plotted alongside the design objective 

force-crush characteristic in Figure 57. The dashed line represents the target force-crush 

characteristic. These results demonstrate that the sequence of events represented by the idealized 

force-crush characteristics are appropriate inputs for the collision dynamics analyses.
77

Figure 57. Example Car-Level Crush Analysis Measured Force-Crush Characteristic
78

Train-Level Evaluation Results

Two key results are required to describe the crashworthiness performance of alternatively

designed equipment for the collision scenario:

1) Crush results demonstrating that occupied volume crush meets the criteria; and

2) Gross motions of each car in the consist to estimate the secondary impact 

environment.

The flowchart in Figure 58 shows a procedure for postprocessing collision dynamics model 

results to evaluate occupied volume crush. The cab layout on cab ends and seating layout at each 

car end determine the points at which occupied space is compromised. The total loss of occupied 

volume in a given analysis must be compared with the values established in Section 3 – Criteria

to determine whether the scenario meets the crashworthiness and occupant protection 

performance criteria.

Figure 58. Flowchart Showing Procedure for Calculating Intrusion into Occupied Volume

Figure 59 shows example results from a collision dynamics analysis. The bar chart shows crush 

at each coupled connection in the initially moving consist. The total crush plotted at each 

connection is the sum of the crush at each of the two connected ends. The points on the 

corresponding force-crush characteristics indicate the amount of car crush at each car end. These 

results demonstrate that occupied volume is preserved throughout the train, because the peak 

load is not exceeded at any car end.
79

Figure 59. Example Crush Results from One-Dimensional Lumped Mass Model: Crush 

Distribution for Each Car End in the Consist

The flowchart in Figure 60 shows a procedure for postprocessing collision dynamics model 

results to estimate the secondary impact environment. Output from the collision dynamics 

analysis includes the acceleration, velocity, and displacement history of each vehicle.

0.0E+00

5.0E+05

1.0E+06

1.5E+06

2.0E+06

2.5E+06

0.0 1.0 2.0 3.0 4.0 5.0 6.0

Crush (ft)

Force (lbf)

Cab End

Non Cab End

Crush (ft)

0

1

2

3

4

5

6

1 2/3 4/5 6/7 8/9 10

Interface

Crush (ft)

CEM @ 35 mph
80

Figure 60. Flowchart Showing Procedure for Calculating SIV Estimates

Following this paragraph are results from a train-to-train collision dynamics analysis. These 

results are shown as an example of the procedures for calculating the secondary impact velocities 

and do not reflect results for the specific collision conditions described in the criteria document.

Figure 61 shows the relative displacement-time data and the relative velocity-time data at the CG 

of each car in the moving consist. The relative displacement (x-axis) and velocity (y-axis) data 

are plotted against one another to develop the SIV characteristics for each car.

Figure 61. Relative Displacement and Relative Velocity Plots for Moving Consist

The SIV characteristics for all of the cars in the moving consist are plotted in Figure 62. From 

this plot, the SIVs can be estimated for allowable travel distance in specific seating 

configurations for each car. These results give an estimate of the severity of the collision 

environment for this equipment with the particular seating configurations planned for use.

Train

Collision

Dynamics

Evaluation

Acceleration

Velocity

Displacement

Secondary Impact 

Velocity
81

Figure 62. Example SIV Characteristics

4.4 Requirement: Occupied Vehicle Integrity

This section includes the criteria and procedures for alternatively evaluating OVI. The example 

procedures outlined in Section 4.4.2 are one way to demonstrate compliance with one of the 

three options. Other procedures may be used.

4.4.1 Criteria

Options

The following options are provided as alternatives to the stated regulation to demonstrate 

sufficient OVI. The equipment must comply with either the regulation or at least one of these 

alternatives.

Option A

Passenger equipment shall resist a minimum quasi-static end load of 800,000 lb applied on the 

collision load path without permanent deformation of the occupied volume.
82

Option B

Passenger equipment shall resist a minimum quasi-static end load of 1,000,000 lb applied on the 

collision load path with limited permanent deformation of the occupied volume. This load shall 

be supported without exceeding either of the following two conditions:

- Local plastic strains of 5 percent; or

- Vehicle shortening of 1 percent over any 15 ft of the occupied volume.

Option C

Passenger equipment shall resist a minimum quasi-static end load of 1,200,000 lb applied on the 

collision load path without crippling the body structure. Crippling of the body structure is 

defined as the maximum point on the load-displacement characteristic. A sample loaddisplacement characteristic is shown in Figure 63.

Figure 63. Example of Load-Displacement Characteristic Indicating Crippling

4.4.2 Example Procedure

The procedures for testing a carbody, analyzing the OVI, and validating the model with test data 

are discussed in further detail in this section.

Testing Procedures

It is expected that quasi-static compression testing will be used as part of a program of model 

validation for any of the three options. The test procedure used should follow a recognized 

national or international standard. Regardless of the standard used, the end load should be a 

minimum of 337,000 lb. This load may otherwise be applied in accordance with the selected 

standard. The standard used shall be clearly identified, and a copy shall be furnished to FRA if 

requested.

Testing may be used either to demonstrate a particular car‘s compliance with an option or as part 

of a program of model validation.

0

200

400

600

800

1000

1200

1400

1600

0 0.5 1 1.5 2 2.5

Displacement (in)

Load (kips)

Crippling Load
83

In all cases, the test procedures should include loading the car to some intermediate load value 

less than the maximum load to be applied. This allows verification that the instrumentation is 

functioning properly as well as provides data that can be used to confirm the predicted behavior 

at the ultimate test load.

Critical measurements for any test should include strains throughout the structure as well as 

deformation of the occupied volume over the course of the test.

Analysis Procedures

Analysis may be used to demonstrate compliance with any of the three options for OVI. Any 

analysis that is being used to demonstrate a given design‘s ability to meet the option must be 

properly validated with test data. Regardless of the option being used, the procedures for 

modeling the occupied volume should be the same, aside from the load magnitude being applied.

Geometry

The entire occupied volume (for both passengers and crewmembers) should be modeled. If the 

carbody is symmetric, symmetry boundary conditions may be used to facilitate efficient 

execution. Couplers (both front and rear), articulations, and CEM components may be removed 

from the model. Mesh size should be sufficiently fine to capture stress details where necessary 

throughout the model.

Materials

Materials used in the model should include their elastic-plastic stress-strain behavior. Where 

possible, material properties derived from material test results should be used. Material 

properties may be assumed to be independent of the rate of deformation. Failure modeling of 

connections (welds, rivets, bolts, etc.) is not required, provided that the analysis does not indicate 

critical stresses/strains in the vicinity of the connectors.

Boundary Conditions

Vertical support for the carbody model should be provided at the locations where it would be 

provided in a physical carbody. In most cases, this would be at the points where the trucks‘

secondary suspension elements interface with the carbody. If an articulation is used in the design, 

vertical support may also be provided at the location of the articulation in the physical car 

structure.

Longitudinal restraint may be provided at the rear end of the car by means of a rigid wall. The 

wall may be divided into multiple parts to facilitate measurement of reaction forces at the floor 

level, wall level, and roof level. The rigid wall is not permitted to move in any direction.

Lateral restraint may be accomplished through a longitudinal-vertical symmetry boundary 

condition. If a longitudinal-vertical symmetry plane is not used in a model, a lateral restraint may 

be provided through the use of a reasonable coefficient of friction between the rear reaction wall 

and the car structure.

Loading

Loading of the occupied volume should resemble the type of loading the occupied volume on a 

physical car would experience during a collision situation. Loads should be applied along the 

collision load path based on the details of the specific design being evaluated. If collision energy 
84

absorbers are removed from the model, loading of the structure may take place through the 

energy absorber supports at the end of the occupied volume. One way of applying these loads is 

through the use of a rigid plate at each energy absorber support location. Each rigid plate would 

have a prescribed displacement that increases with time, allowing the plate to make contact with 

the energy absorber support in a manner similar to that of the energy absorber reacting against its 

support.

The prescribed load rate applied to each rigid plate should be the same for a given car design.

The rate should be chosen carefully to avoid introducing dynamic effects to the simulation. For 

all three options, OVI is to be demonstrated for a quasi-static loading case. It is important to 

ensure that the model is predicting the quasi-static behavior of the car free from dynamic effects.

An analysis conducted in accordance with either of the next two conditions should be considered 

quasi-static.

Condition One

For a given simulated load rate, the load at the live end of the model should be the same as the 

load at the fixed end. Load at the reaction end may vary by up to ±5 percent of the load at the 

live end of the model for the analysis to be considered quasi-static. Figure 64 depicts two 

example load-displacement characteristics for the same model, one generated at the point of load 

application and one generated at the reaction location. A ±5 percent envelope is plotted on this 

example graph to demonstrate the quasi-static nature of the analysis.

Figure 64. Example Load-Displacement Characteristics at Front and Back End with 

5 Percent Envelope

Condition Two

The ratio of kinetic energy to strain energy within the structure should be small (<5 percent). The 

ratio of kinetic energy-to-strain energy may exceed 5 percent during the first 10 percent of the 

Crippling Analysis - 12.2 ips

[0.3 m/s] 

0

200

400

600

800

1000

1200

1400

1600

0 0.25 0.5 0.75 1 1.25 1.5 1.75 2 2.25

Displacement (in)

Force (kips)

Applied Force

+/- 5%

Reaction Force
85

total simulation time without invalidating the analysis as quasi-static. Figure 65 shows a sample 

graph of kinetic energy to internal energy plotted against the normalized analysis time.

Figure 65. Example Ratio of Kinetic Energy to Strain Energy for Analysis

Validation Procedures

If analysis is used to demonstrate compliance with any of the three options, the model used must 

be validated with test data. The model should be validated with data from a compressive strength 

test of the occupied volume. The load may be applied to the vehicle in a manner consistent with 

the governing design standard, with an end load magnitude no less than 1,500 kN (337,000 lb) 

regardless of the load magnitude required by the design standard.

The same occupied volume finite element model should be used to simulate the test and 

demonstrate compliance with an option. For validation analyses, the effects of gravity should be 

included in the model. Critical measurements to be compared between tests and analyses include 

the overall decrease in length of the car, the vertical deflection of the car, and the strain state in 

the car. Strain measurement locations should be chosen to minimize the local effects resulting 

from features such as welds, sharp corners, and geometric features that are not relevant to the 

occupied volume‘s global behavior. For displacement data, analytical results within ±10 percent 

of the test measurements should be considered as acceptable validation. For strain data, 

analytical results within ±20 percent of the test measurements should be considered as acceptable 

validation.

Procedures Specific to Option A

Compliance with Option A requires demonstrating (through testing or a combination of testing 

and analysis) that at a load of 800,000 lb distributed along points in the collision load path, the 

occupied volume experiences no permanent deformation.

For a test, the pass/fail criterion of ―no permanent deformation‖ may be verified by a lack of 

visible damage as well as displacement measurements indicating no permanent set in the overall 

0%

1%

10%

100%

1000%

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Normalized Time

Energy Ratio

Kinetic/Internal

5%
86

dimensions of the car. In addition, strain gage results should not indicate stresses above the yield 

stress of the material.

For compliance demonstrated by analysis, highly localized areas of stress exceeding yield 

(―hotspots‖) may be allowed as discussed below. An analysis may include the designated energyabsorbing elements, or these may be removed. If the energy-absorbing elements remain within 

the model, permanent deformation within designated energy-absorbing areas should not 

constitute failure to meet Option A.

Plastic strains can develop in a model that would not be apparent in a test under the same 

conditions, in many cases, because of assumptions and simplifications made in any finite 

element model. For example, sharp corners and idealized member-to-member connections may 

result in artificially high strains in localized regions. In consideration of this, plastic strains may 

be permitted within an analysis that otherwise demonstrates meeting Option A under all of the 

following conditions:

 Plastic analysis of the model shows the affected areas to be small with plastic strain not 

exceeding 1 percent;

 With removal of the simulated load, there is no permanent set in the overall dimension of 

the occupied volume; and

 The function of the structure is not compromised.

Deliverables should include, at a minimum:

 Contour plots indicating maximum strains in model under 800,000-pound load;

 Contour plots indicating deformation (vertical, lateral, and longitudinal) in model under 

800,000-pound load;

 Evidence of model validation, including comparison of test and analytical deflections and 

stresses;

 Load-displacement characteristic, including loading and unloading behavior for the entire 

structure; and

 Load-displacement characteristics at each load application point.

Procedures Specific to Option B

Using a validated finite element model, demonstrate that at a load of 1,000,000 lb in line with the 

collision load path, the maximum plastic strain experienced by the structure of the car is 

<5 percent. Under this load condition, vehicle shortening may not exceed 1 percent for any 

15-foot length of occupied volume.

Plastic strains may develop that exceed the 5 percent permitted under Option B. In many cases,

these strains develop because of assumptions and simplifications made in any finite element

model. For example, sharp corners and idealized member-to-member connections may result in 

artificially high strains in localized regions. In consideration of this, plastic strains exceeding 

5 percent should be permitted within an analysis that otherwise demonstrates meeting Option B 

under all of the following conditions:
87

 The maximum plastic strain value is <10 percent; and

 Strains exceeding 5 percent are not located on any primary longitudinal load carrying 

component.

Deliverables should include, at a minimum:

 Contour plots indicating maximum strains in the model under the 1,000,000-pound load;

 Contour plots indicating deformation (vertical, lateral, and longitudinal) in the model 

under the 1,000,000-pound load;

 Evidence of model validation, including comparison of test and analytical deflections and 

stresses;

 Load-displacement characteristic up to 1,000,000 lb for the entire structure; and

 Load-displacement characteristics at each load application point.
88

Procedures Specific to Option C

Using a validated finite element analysis, researchers demonstrate that the crippling load is 

>1,200,000 lb. This property can be readily observed on a load-displacement characteristic. Note 

that for vehicles with crippling loads exceeding 1,200,000 lb, only that portion of the 

characteristic showing no crippling at 1,200,000 lb needs to be provided. Figure 66 shows a 

sample load-displacement characteristic taken from the front and back of the same car model.

This example characteristic only shows the force up to 1,200,000 lb, at which point crippling has 

not yet occurred.

Figure 66. Example Load-Displacement Characteristic Showing Crippling Load Exceeds 

1,200,000 lb

Deliverables should include, at a minimum:

 Contour plots indicating maximum strains in the model under the 1,200,000-pound load;

 Contour plots indicating deformation (vertical, lateral, and longitudinal) in the model 

under the 1,200,000-pound load;

 Evidence of model validation, including comparison of test and analytical deflections and 

stresses;

 Load-displacement characteristic up to 1,200,000 lb for the entire structure; and

 Load-displacement characteristics at each load application point.

If analysis is taken beyond crippling, contour plots for strain and deflection at crippling load 

should also be provided.

Crippling Analysis - 12.2 ips

[0.3 m/s] 

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Displacement (in)

Force (kips)

Applied Force

Reaction Force
89

4.5 Requirement: Colliding Equipment Override

This section includes the criteria and example procedures for evaluating colliding equipment

override. The procedures and results in this section show the types of analyses and results that 

demonstrate compliance with the criteria. Other procedures may be used in evaluating a 

particular vehicle design.

4.5.1 Criteria

Given the scenario described in Section 3.1, anticlimb features shall be demonstrated for each of

the following sets of initial conditions:

1) All cars in the moving and standing consists are positioned at their nominal running 

height.

2) The interface of the colliding equipment is perturbed laterally and vertically by 3 in.

The pass/fail criteria are as follows:

 The relative difference in elevation of the underframes between the colliding and 

connected equipment shall not change by more than 4 in; and

 The tread of any wheel of the alternatively designed equipment shall not rise above the 

top of rail more than 4 in.
90

4.5.2 Example Procedure

The following example procedure illustrates the type of crush analyses performed on the FRAPrototype CEM Equipment to demonstrate that the anticlimb features will limit the potential for 

override in a train-to-train collision scenario. Two different collision scenarios are analyzed: one

impact under ideal conditions and second impact under offset conditions. Figure 67 shows the 

initial conditions for an offset analysis with the conventional locomotive lowered and moved 

laterally by a prescribed amount. This analysis was run in preparation for a test, and the offset 

values do not match those given in Section 3 – Criteria. However, the same analysis techniques 

used to prepare for the test may be used to show that the criteria are met.

Figure 67. Dynamic Crush Analysis with Lateral and Vertical Offsets

Note that although only the impacting interface is shown in this figure, compliance with the 

criteria requires analysis of the alternatively designed equipment in the configuration intended 

for use. If the alternatively designed equipment may be used in multiple configurations (e.g., a

single four-car trainset, or two four-car trainsets coupled together), analysis of each such 

configuration is required.

4.5.3 Example Key Results

Figure 68 and Figure 69 show the deformation of the cab car from the analysis under ideal 

conditions and from the offset case, respectively. In both cases, the cab car lifted <1 in, and the 

vertical displacement of the conventional locomotive was negligible. In neither case were any of 

the trucks unloaded nor did any wheel lift occur. Consequently, these analyses demonstrate the 

requirements of the criteria are met.

Model fixed along 

car mid-plane 30 mph

Close-up Side View Close-up Bottom View
91

Figure 68. Displacement Results from Dynamic Crush Analysis: Ideal Impact Conditions

Figure 69. Displacement Results from Dynamic Crush Analysis: Offset Impact Conditions
92

4.6 Requirement: Connected Equipment Override

This section includes the criteria and example procedures for evaluating connected equipment 

override. The procedures and results in this section show the types of analyses and results that 

demonstrate compliance with the criteria. Other procedures may be used in evaluating a 

particular design.

4.6.1 Criteria

Given the scenario described in Section 3.1, anticlimb features shall be demonstrated for each of 

the following sets of initial conditions:

1) All cars in the moving and standing consists are positioned at their nominal running 

heights.

2) The first car-to-car interface of the initially-moving consist is perturbed laterally and 

vertically by 2 in.

Figure 70. Location of Offsets in Moving Consist

Figure 71. Illustration of Offset for Coupled Cars

2 inch vertical and 

lateral offsets
93

Figure 72. Illustration of Offset for Articulated Cars

The pass/fail criteria are as follows:

 The relative difference in elevation between the underframes of the colliding and 

connected equipment shall not change by more than 4 in; and

 The tread of any wheel of the alternatively designed equipment shall not rise above the 

top of rail more than 4 in.

4.6.2 Example Procedure

Using a finite element model that included the first two cars of the passenger train and the rigid 

geometry of the standing locomotive, a dynamic crush analyses was conducted to evaluate the 

ideal impact conditions.

The same model can be used with different initial conditions for the offset impact condition.

Figure 73 shows the model used for the ideal condition example analysis. This analysis was 

performed by Alstom, on a multilevel, MU trainset.

Figure 73. Dynamic Crush Analysis: Ideal Impact Conditions (Courtesy of Alstom)
94

1.1.1 4.6.3 Example Key Results

Figure 74 is a graphic from the analysis at the time of maximum vertical displacement between 

the two cars at the first coupled interface. There are various labels on the figure indicating points 

that were tracked for vertical displacement. Also, in the lower-right portion of the figure there is 

a red oval around the gooseneck area of the underframe. There was a modest amount of 

permanent deformation at this location, which was the principal source of the vertical motion.

Figure 74. Deformation in Coupled Car Dynamic Crush Analysis: Ideal Impact Conditions 

(Courtesy of Alstom)

Figure 75 shows the time history of the relative vertical displacement between the two coupled 

cars shown in Figure 74. The maximum relative displacement is 1.6 in, which is less than the 4 

in allowed by the criteria.

Figure 75. Relative Vertical Displacement of the Underframes of Two Coupled Cars 

(Courtesy of Alstom)
95

Figure 76 shows the vertical displacement-time history of the wheels seen in Figure 74. As can 

be seen on the plot shown in the figure, the wheels remain on the track for the entire simulation.

This demonstrates compliance with the criteria that no wheel lifts above the rail by 4 in or more.

Figure 76. Vertical Displacement of Four Wheels (Courtesy Alstom)
96

4.7 Requirement – End Structure Integrity of Cab End

This section describes analysis and test procedures that may be used to show compliance with 49 

CFR 238, Appendix F. Three examples are provided: one based on a full-scale dynamic impact 

test of a conventional cab car, a second based on component tests for a conventional cab car, and 

a third based on component tests for a CEM cab. Analysis is used in all three cases, and an 

example procedure for analysis is described first. The full-scale tests are then described, 

followed by the component tests for the conventional cab car, and finally the component tests for 

the CEM cab car. Both quasi-static and dynamic tests are described for the CEM equipment.

Three examples are provided in order to more fully describe the range of equipment that can be 

addressed with Appendix F and to more fully describe the range of procedures that may be used 

to show compliance. However, what is described here is illustrative and is not prescriptive. Other 

engineering procedures that provide a comparable level of confidence in the crashworthiness 

performance of the cab car end frame may also be used.

4.7.1 Criteria

Option

Title 49 CFR

§ 238.209. Forward end structure of locomotives, including cab cars and MU locomotives

Appendix F to Part 238—Alternative Dynamic Performance Requirements for Front End 

Structures of Cab Cars and MU Locomotives

These subparts are excerpted in Appendix B. Selected CFR References.

******************************************************************************
97

4.7.2 Example Procedures

Procedures for evaluating the end structure integrity for the cab end are divided into two major 

categories: analysis and testing. It is anticipated that a combination of testing and analysis will be 

used to demonstrate compliance with 49 CFR 238, Appendix F. Three testing example 

procedures are presented: a full-scale test of an entire car, a full-scale test of the end structure 

components, and a series of component tests for a CEM cab car.

Example Procedures: Analysis

Analysis is a crucial part of demonstrating that the requirements of the quasi-static or dynamic 

scenario are met. Analysis should be performed before designing any tests. For the corner and 

collision post test scenarios, a symmetric model cannot be used, because the loading is not 

symmetric. The model can be truncated in the longitudinal direction so that only the cab end is 

modeled. The model should contain sufficient length of the car so that there is no strain at the 

truncated end. The finite element model should be of the test condition, with the rigid indenter 

described in the rule. The model should show that the end frame meets the requirements in § 

238.211 and § 238.213, or in Appendix F.

For the FRA prototype state-of-the-art (SOA) end frame design and the corresponding full-scale 

tests, a sophisticated finite element model was built and refined. On the basis of the results of the 

2002 full-scale dynamic test in which a heavy steel coil impacted the corner post of an SOA end 

frame design, some fracture was expected in certain key end frame components during the 2008 

tests. For this reason, a material failure model, based on the Bao-Wierzbicki fracture criterion, 

was implemented in the finite element model of the car end frame using the general purpose FE 

software program ABAQUS/Explicit. The finite element model with material failure was used to 

assess the effect(s) of fracture on the deformation behavior of the car end structures during quasistatic and dynamic testing. Particular attention was paid to the ability of such structures to absorb 

energy.

The material failure model was implemented in ABAQUS/Explicit for use with shell elements. A 

series of preliminary simulations was first conducted to assess the effects of element type and 

mesh refinement on the deformation and fracture behavior of structures similar to those found on 

cab car and MU locomotive end frames and to demonstrate that the Bao-Wierzbicki failure 

model can be effectively applied using shell elements.

Model parameters were validated through comparison to the results of the 2002 testing. Material 

strength and failure parameters were derived from test data for A710 steel. The model was then 

used to simulate the three full-scale tests that were conducted during 2008 as part of the FRA 

program—dynamic impact testing of a collision post, and quasi-static load testing of a collision 

post and a corner post. Analysis of the results of the two collision post tests revealed the need for 

revisions to both the design of some key end frame components and to key material failure 

parameters. With the revised model, pretest predictions for the outcome of the corner post test 

were found to be in very good agreement with the actual test results.

Overall, the results of the tests in comparison with their pretest analyses show that, at this time, 

actual testing is necessary to demonstrate performance. However, as modeling methods improve 
98

and are shown to predict failure and energy absorption more accurately, there is the potential that 

use of analysis alone will in the future be acceptable for demonstrating crashworthiness 

performance.

Example Procedure: Full-Scale Test

For the example test, a 14,000-pound cart impacted a standing cab car at a speed of 18.7 mph. 

The cart had a rigid coil shape mounted on the leading end that concentrated the impact load on 

one collision post. The requirements for protecting the engineer‘s space state that there can be no 

more than 10 in of longitudinal deflection, and none of the attachments of any of the structural 

members may separate. Figure 77 shows still photographs of the test, taken from the high-speed 

video.

Figure 77. Still Photographs from High-Speed Video, Collision Post Test

During the test, the collision post deformed inward by approximately 7.4 in and absorbed 

approximately 138,000 ft-lb of energy. The attachment between the post and the roof member 

(AT beam) remained intact. The connection between the post and the floor member (buffer 

beam) did not completely separate; however, the forward flange and both side webs fractured. 

The post itself did not completely fail. There was material failure in the back and the sides of the 

post at the impact location. Overall, the end frame was successful in absorbing energy and 

preserving space for the operating crew and the passengers.

Example Procedure: End Frame Component Test

For some designs, including the SOA end frame, it may be permissible to run a component test 

of the end frame of the car rather than a test of the entire vehicle. An analysis of the scenario, 

either quasi-static or dynamic, should be performed. This test is appropriate when pretest

analysis shows the end frame deforms to meet the scenario requirements, but the carbody 

inboard of the end frame does not deform.

Figure 78 and Figure 79 show the equivalent plastic strain taken from pretest finite element

models of the SOA corner and collision posts. Dashed red lines on the figures indicate where the 

end frame could be truncated for a component test. For this end frame, the longitudinal 

connecting members for the AT beam and the buffer beam experience deformation, whereas the 

roof rails and the side sill do not. Also, the draft sill does not experience deformation.
99

Figure 78. Contours of Equivalent Plastic Strain for the Quasi-Static Collision Post Load 

Case

Figure 79. Contours of Equivalent Plastic Strain for the Quasi-Static Corner Post Load 

Case

PEEQ

PEEQ
100

Once the deformable region has been determined, a test component and a test fixture need to be 

designed. The test component for the SOA end frame is similar to the component shown in 

Figure 80. The test component contains all the parts that are likely to deform under the scenario, 

as shown by the analysis. The test fixture should be designed to hold the component fixed, 

possibly against a wall or on the ground. Once the test fixture and the test component have been 

designed and fabricated, a quasi-static or dynamic load can be imparted to the test article. The 

energy imparted to the test article should be equal to or greater than 135,000 ft-lb for the 

collision post location and ≥120,000 ft-lb for the corner post location. The structure should 

deform by less than 10 in while absorbing the required amount of energy. A separate test should 

be run for each location. Although it is permissible to use the very same test specimen to 

demonstrate compliance with both of these sections, the forces imparted to the test specimen for 

purposes of demonstrating compliance with one set of these requirements may weaken the 

sample structurally and thus make it more difficult to demonstrate compliance with the other set 

of requirements. Consequently, the final rule does not impose the additional obligation to use the 

very same test specimen to demonstrate compliance with both the requirements of § 238.211 and 

those of § 238.213.

Figure 80. Test Component Approximation for Component Test

Once the FE model has been validated, particularly the modeling of fracture, it is possible that 

future minor modifications to the end frame design can be evaluated using analysis only, rather 

than testing.
101

Combined Component Test and Analysis: Crushable Component Example

For some designs, it might be permissible that only crushable elements will need to be tested. For 

this to occur, the analysis must show that nearly all the required energy is absorbed in the 

crushable elements. The support structure to the crushable elements must not appreciably 

deform.

Figure 81 shows an example CEM cab car design with crushable components. For this 

hypothetical scenario, all the energy is absorbed by the crushable elements. The analysis should 

show that no energy is absorbed by the supporting structure. For this example, either the quasistatic or the dynamic scenario can be evaluated.
102

Figure 81. Example Analysis Results of Car with Deformable Energy Absorbers

Figure 82 shows an example of a dynamic drop tower test of a CEM crushable component. 

Figure 83 shows an example of a quasi-static test of a CEM crushable component. Either type of

test is acceptable for a component test. The test instrumentation should measure key 

characteristics of the component, including force-crush behavior and mode of deformation. The 

results of the component test should be compared with the analysis predictions. The analysis 

should be refined to match the test results if necessary.
103

Figure 82. Example of a Dynamic Drop Tower Test of a CEM Component

Figure 83. Example of a Quasi-Static Test of a CEM Component

Table 6 summarizes the analyses and tests conducted to verify that the design complies with 

Appendix F. Detailed analyses are performed on the components and on the car. The component 

models are verified with tests. The component models are used to assemble the car model.
104

Table 6. Example Matrix of Component Testing and Analyses

Component Detailed Analysis Component Testing

Component Level Car Level

Outboard Energy 

Absorber

Yes Yes Dynamic

Center Energy 

Absorber

Yes Yes Static
105

4.8 Requirement – End Structure Integrity of Noncab End

4.8.1 Criteria

Collision Post Option

Collision posts are not required for equipment with pushback couplers and interlocking anticlimbers, intercar connection is capable of preventing disengagement and telescoping to the 

same extent as equipment satisfying the anticlimbing and collision post requirements contained 

in 49 CFR Part 238. (See Option for § 238.205, Anticlimbing mechanism, for description of 

criteria for determining whether the connection is capable of preventing disengagement and 

telescoping to that extent.)

Corner Post Option

(a) Each passenger car shall have at each end of the car, placed ahead of the occupied volume, 

two side structures capable of resisting:

(1) A 150,000-pound horizontal force applied at floor height without failure;

(2) A 20,000-pound horizontal force applied at ceiling height without failure; and

(3) A 30,000-pound horizontal force applied at a point 18 in above the top of the floor without 

permanent deformation.

(b) For the purposes of this option, the orientation of the applied horizontal forces shall range 

from longitudinal inward to transverse inward.
106

4.8.2 Example Procedures

Criteria 1: 150,000 lb at Underframe Attachment without Failure

Analysis Method

There are multiple ways of demonstrating compliance through analysis, such as 1) manual 

calculations or 2) a quasi-static nonlinear finite element model of the end structure that 

incorporates material failure. The load may be introduced through a rigid indenter with an 

area no larger than 6 × 6 in that is applied to the vehicle at the point of attachment of the side 

structure to the underframe. The resulting force-crush curve must show that the structure can 

withstand 150,000 lb with no structural failure anywhere in the vehicle. Figure 84 shows a 

schematic of the load application scenario.

Figure 84. Side View of Car Showing 150-Kilopound Load

Testing Method

Compliance may be demonstrated with a full-scale vehicle test. A test fixture with an area no 

larger than 6 × 6 in may be used to apply the load at the point of attachment of the side 

structure to the underframe. The resulting measured force-crush curve must show that the 

structure can withstand 150,000 lb with no structural failure anywhere in the vehicle.

Roof Structure

Side 

Structure

Underframe

Side View of Car

150 kips
107

Criteria 2: 20,000 lb at Roof Attachment without Failure

Analysis Method

There are multiple ways of demonstrating compliance through analysis, such as 1) manual 

calculations or 2) a quasi-static nonlinear finite element model of the end structure that 

incorporates material failure. The load may be introduced through a rigid indenter with an 

area no larger than 6 × 6 in that is applied to the vehicle at the point of attachment of the side 

structure to the roof structure. The resulting force-crush curve must show that the structure 

can withstand 20,000 lb with no structural failure anywhere in the vehicle. Figure 85 shows a 

schematic of the load application scenario.

Figure 85. Side View of Car Showing 20-Kilopound Load

Testing Method

Compliance may be demonstrated with a full-scale vehicle test. A test fixture with an area no 

larger than 6 × 6 in may be used to apply the load at the point of attachment of the side 

structure to the roof structure. The resulting measured force-crush curve must show that the 

structure can withstand 20,000 lb with no structural failure anywhere in the vehicle.

Roof Structure

Underframe

Side View of Car

20 kips

Side 

Structure
108

Criteria 3: 30,000 lb 18 in above Floor without Permanent Deformation

Analysis Method

There are multiple ways of demonstrating compliance through analysis, such as 1) manual 

calculations or 2) a quasi-static nonlinear finite element model of the end structure that 

incorporates material failure. The load may be introduced through a rigid indenter with an 

area no larger than 6 × 6 in that is applied to the vehicle at the side structure 18 in above the 

level of the floor. The analysis must show that the structure can withstand 30,000 lb with no 

permanent deformation anywhere in the vehicle outside of the point of load application. 

Figure 86 shows a schematic of the load application scenario. Figure 87 shows an example of 

the load being applied to a finite element model with a rigid indenter.

Figure 86. Side View of Car Showing 30-Kilopound Load

Roof Structure

Underframe

Side View of Car

30 kips

18 in. from floor

Side 

Structure
109

Figure 87. Finite Element Model Showing Side Structure Load and Boundary Conditions

Testing Method

Compliance may be demonstrated with a full-scale vehicle test. A test fixture with an area no 

larger than 6 × 6 in may be used to apply the load to the side structure 18 in above the floor. 

The resulting measurements must show that the structure can withstand 30,000 lb with no 

permanent deformation anywhere in the vehicle.

Fixed along car 

mid-plane

Rigid indenter 
110

4.9 Requirement: Truck Attachment

This section includes the criteria and example procedures for evaluating truck attachment 

strength. The procedures and results in this section show the types of analyses and results that 

demonstrate compliance with the criteria. Other procedures may be followed in demonstrating 

compliance.

4.9.1 Criteria

The following options are provided as alternatives to the stated regulation in order to 

demonstrate sufficient truck-to-car-body attachment. The equipment must comply with either the 

regulation or at least one of these alternatives to demonstrate compliance with the criteria stated 

in this document.

Option A

Passenger equipment shall have a truck-to-carbody attachment with strength sufficient to resist 

without yield the following individually applied quasi-static loads on the mass of the truck at its 

CG: 3g vertically; 5g longitudinally, along with the resulting vertical reaction to this load; and 1g 

laterally, along with the resulting vertical reaction to this load. For the purposes of this option, 

the mass of the truck includes axles, wheels, bearings, the truck-mounted brake system, 

suspension system components, and any other component attached to the truck by design.

In addition, for the nominal initial condition given in the scenario described in Section 3.1:

 The average longitudinal deceleration of the car during the impact shall not exceed 5g; 

and

 The peak longitudinal deceleration of the truck shall not exceed 10g.

******************************************************************************

Option B

Passenger equipment shall have a truck-to-carbody attachment with strength sufficient to resist 

without yield the following individually applied quasi-static loads on the mass of the truck at its 

CG: 3g vertically and 1g laterally, along with the resulting vertical reaction to these loads. For 

the purposes of this option, the mass of the truck includes axles, wheels, bearings, the truckmounted brake system, suspension system components, and any other component attached to the 

truck by design.

In addition, the truck shall remain attached during the scenario described in Section 3.1.

******************************************************************************

4.9.2 Example Procedure

The truck attachment was evaluated using Option A in this example. This evaluation was made 

through the results of a single simulation. This simulation was performed for ideal, in-line initial 

conditions. This same simulation was also used to evaluate the Scenario (described in Section 

3.1), Colliding Equipment Override (Section 3.3), and Connected Equipment Override

(Section 3.4). The model is shown in Figure 73.
111

4.9.3 Example Results

Figure 88 shows the deceleration-time history of the cab car described in Section 4.8 and Figure 

89 shows the deceleration-time history of the lead truck of that cab car. As shown in Figure 88, 

the average deceleration of the cab car was just over 4g, which is less than the 5g permitted by 

the criteria. The average deceleration was calculated from initial contact between the cab car and 

locomotive until the contact force dropped to 0. The peak deceleration of the cab car is 15g, 

which is nearly four times the average deceleration. The cab car deceleration time-history shown 

in Figure 88 is a direct output from the simulation. As shown in Figure 89, the maximum 

deceleration of the truck is 10g, which is the maximum permitted by the criteria. The truck 

deceleration time-history is also a direct output from the simulation and has been filtered with a 

zero-phase fourth-order Butterworth filter meeting the SAE CFC 100 specification. The 

simulation results indicate both of the criteria are met.

Figure 88. Cab Car Deceleration-Time History (Courtesy of Alstom)
112

Figure 89. Cab Car Lead Truck Deceleration-time History (Courtesy of Alstom)
113

4.10 Summary and Next Steps

Criteria and procedures for assessing the crashworthiness and occupant protection performance 

of alternatively designed equipment to be used in Tier I service have been developed. These 

criteria and procedures take advantage of the latest technology in rail equipment 

crashworthiness; they also include aspects that are fundamentally different from current 

regulations, such as the scenario-based, train-level requirements. No such requirements are 

specified in FRA‘s current Tier I regulations. Numerical values of the pass/fail criteria have been 

selected to provide a level of crashworthiness equivalent to the current Tier I regulations. For 

example, the OVI requirements have been relaxed from the current regulations, and criteria for 

preservation of the occupied volume for a collision with a conventional locomotive-led train 

have been added to compensate. In other cases, such as for roof integrity, the existing regulations 

can be directly applied to alternatively designed equipment and are unchanged.

Because the latest technology in rail equipment crashworthiness has been used as a basis for the 

criteria and procedures, many aspects of the resulting criteria and procedures are fundamentally 

different from their corresponding regulations. Although technical results from sophisticated 

analyses and tests have been necessary, judgment was also needed to develop the criteria and 

procedures. This judgment was provided by ETF and accepted by FRA. It is anticipated that the 

product of this effort—the criteria and procedures—and the process used—the 

government/industry working group—will serve as the model for the development of criteria and 

procedures by which to evaluate alternatively designed passenger equipment with other safety 

regulations.
114

5. References

1. Tyrell, D., Martinez, E., Jacobsen, K., Parent, D., Severson, K., Priante, M., & Perlman, 

A. B. Overview of a Crash Energy Management Specification for Passenger Rail 

Equipment, American Society of Mechanical Engineers, Paper No. JRC2006-94044, 

April 2006.

2. Code of Federal Regulations, Title 49, Part 238, Subpart E—Specific Requirements for 

Tier II Passenger Equipment.

3. EN 15227, Railway Applications—Crashworthiness Requirements for Railway Vehicle 

Bodies, Ref. No. EN15227:2008:E.

4. Tyrell., D., & Tsai., T. Improved Crashworthiness of Rail Passenger Equipment in the 

United States, World Congress on Railway Research, Montreal, Canada, June 2006.

5. Lacôte, F., Cléon, L.-M., Lagneau, H., Dannawi, M., Demonsant, E., & Wiart, A. Les 

Tolérances á la Collision Des Matérials Ferroviaires, Revue générale des chemin de fer, 

Gauthier-Villars, November 1993.

6. Scholes, A., & Lewis, J. Development of Crashworthiness for Railway Vehicle 

Structures, Proceeding of the Institute of Mechanical Engineers, Vol. 207 Part F: Journal 

of Rail and Rapid Transit, 1993.

7. Tyrell, D. C., & Perlman, A. B. Evaluation of Rail Passenger Equipment 

Crashworthiness Strategies, Transportation Research Record No. 1825, pp. 8-14, 

National Academy Press, 2003.

8. Bing, A. Collision Avoidance and Accident Survivability, Volume 1: Collision Threat,

DOT/FRA/ORD-93-02.I, FRA, U.S. Department of Transportation, 1993.

9. Tyrell, D., Jacobsen, K., & Martinez, E. A Train-to-Train Impact Test of Crash Energy 

Management Passenger Rail Equipment: Structural Results, American Society of 

Mechanical Engineers, Paper No. IMECE2006-13597, November 2006.

10. Carolan, M., & Muhlanger, M. Strategy for Alternative Occupant Volume Testing, 

American Society of Mechanical Engineers, Paper No. RTDF2009-18025, October 2009.

11. Tyrell, D. C., Severson, K. J., & Marquis, B. J. Analysis of Occupant Protection 

Strategies in Train Collisions, American Society of Mechanical Engineers, AMD-Vol. 

210, BED-Vol. 30, pp. 539-557, 1995.
115

12. Parent, D., Tyrell, D., & Perlman, A. B. Evaluating Abdominal Injury in Workstation 

Table Impacts, Compendium of Papers, 84th Annual Meeting, Transportation Research 

Board, January 2005.

13. Severson, K., Perlman, A. B., & Stringfellow, R. Quasi-Static and Dynamic Sled Testing 

of Prototype Commuter Rail Passenger Seats, American Society of Mechanical 

Engineers, Paper No. JRC2008-63051, April 2008.

14. Carolan, M. Evaluation of Occupant Volume Strength in Conventional Passenger 

Railroad Equipment, Tufts University Master‘s Thesis, May 2008

15. Tyrell, D. Passenger Rail Train-to-Train Impact Test Volume I: Overview and Selected 

Results, U.S. Department of Transportation, DOT/FRA/ORD-03/17.I, July 2003.

16. Tyrell, D., & Martinez, E. A Train-to-Train Impact Test of Crash Energy Management 

Passenger Rail Equipment, Sixth International Symposium on the Passive Safety of Rail 

Vehicles, Berlin, Germany, December 2006.

17. Rancatore, B., Llana, P., Van Ingen-Dunn, C., & Bradney, C. Occupant Protection 

Experiments in Support of a Full-Scale Train-to-Train Crash Energy Management 

Equipment Collision Test, U.S. Department of Transportation, DOT/FRA/ORD-09/14, 

July 2009.

18. Parent, D., Tyrell, D., Rancatore, R., & Perlman, A. B. Design of a Workstation Table 

with Improved Crashworthiness Performance, American Society of Mechanical 

Engineers, Paper No. IMECE2005-82779, November 2005.

19. Tyrell, D., Jacobsen, K., Parent, D., & Perlman, A. B. Preparations for a Train-to-Train 

Impact Test of Crash-Energy Management Passenger Rail Equipment, American Society 

of Mechanical Engineers, Paper No. IMECE2005-70045, March 2005.

20. Severson, K., & Parent, D. Train-to-Train Impact Test of Crash Energy Management 

Passenger Rail Equipment: Occupant Experiments, American Society of Mechanical 

Engineers, Paper No. IMECE2006-14420, November 2006.

21. Code of Federal Regulations, Title 49, Part 571, Standard No. 208, Occupant Crash 

Protection, October 2002.

22. APTA SS-C&S-016-99, Rev. 1, Standard for Row-to-Row Seating in Commuter Rail 

Cars, American Public Transportation Association, Washington, DC.

23. Code of Federal Regulations, Title 49, Part 238, Subpart C—Specific Requirements for 

Tier I Passenger Equipment.
116

24. EN12663, Railway Applications – Structural Requirement of Railway Vehicle Bodies –

Part 1: Railway Vehicles Other than Freight Wagons, Ref. No. prEN12663-1:2007

25. Cothen, G., Schulte, C., Horn, J., & Tyrell, D. Consensus Rulemaking at the Federal 

Railroad Administration, TR News, Transportation Research Board, Number 236, 

January-February 2005.

26. Priante, M., Tyrell, D., & Perlman, A. B. The Influence of Train Type, Car Weight, and 

Train Length on Passenger Train Crashworthiness, American Society of Mechanical 

Engineers, Paper No. IMECE2005-70042, March 2005.

27. National Transportation Safety Board. Head-On Collision between BNSF and Metrolink 

Trains, and Subsequent Derailment, in Placentia, California on April 23, 2002: Factual 

Report, Survival Factors Issues. DCA- 02-MR-004, 2/20/03.

28. Petition of Peninsula Joint Powers Board/Caltrain for Approval of Mixed Use and Waiver 

of Certain Federal Railroad Administration Regulations Pursuant to 49 CFR Section 

238.203, 49 CFR Section 238.205, 49 CFR Section 238.207, 49 CFR Section 238.211, 49 

CFR Section 238.213. Docket ID: FRA-2009-0124.

29. American Public Transportation Association, Member Services Department, Manual of 

Standards and Recommended Practices for Passenger Rail Equipment, Issue of July 1, 

1999.

30. Tyrell, D., Severson, K., Zolock, J., & Perlman, A. B. Passenger Rail Two-Car Impact 

Test Volume I: Overview and Selected Results, U.S. Department of Transportation, 

DOT/FRA/ORD-01/22.I, January 2002.

31. Jacobsen, K., Tyrell, D., & Perlman, A. B. Impact Tests of Crash Energy Management 

Passenger Rail Cars: Analysis and Structural Measurements, American Society of 

Mechanical Engineers, Paper No. IMECE2004-61252, November 2004.

32. National Transportation Safety Board. Railroad Accident Report: Head-On Collision of 

Boston and Maine Corporation Extra 1731 East and Massachusetts Bay Transportation 

Authority Train No. 570 on Former Boston and Maine Corporation Tracks, Beverly, 

Massachusetts, August 11, 1981, PB82-916301, NTSB-RAR-82-1, 1982.

33. Jacobsen, K. Collision Dynamics Modeling of Crash Energy Management Passenger Rail 

Equipment, Tufts University Master‘s Thesis, January 2008.

34. National Transportation Safety Board. Railroad Accident Report: Collision of Metrolink 

Train 111 with Union Pacific Train LOF65–12 Chatsworth, California, September 12, 

2008, RAR-10-01.
117

35. Tyrell, D. C., Martinez, E. E., & Wierzbicki T. Crashworthiness Studies of Locomotive 

Wide Nose Short Hood Designs, Crashworthiness, Occupant Protection and 

Biomechanics in Transportation Systems. American Society of Mechanical Engineers, 

AMD Vol. 237/BED Vol. 45, 1999.

36. Thompson, W. T. Theory of Vibration with Applications, Prentice-Hall, Inc., 1981.

37. Tyrell, D. C., Severson, K. J., & Marquis, B. J. Crashworthiness of Passenger Trains,

U.S. Department of Transportation, DOT/FRA/ORD-97/10, 1998.

38. Code of Federal Regulations, Title 49, Appendix F to Part 238—Alternative Dynamic 

Performance Requirements for Front End Structures of Cab Cars and MU Locomotives.
118

Appendix A. Selected Train Incidents

Passenger train accidents can occur under a wide range of circumstances, but those that can be 

mitigated by crashworthiness features of the train can be placed into three broad categories:

1. Collisions with another train

2. Collisions with objects, such as at a grade-crossing

3. Single train events, such as a derailment

Further classifications can be made within each of these categories. For example, significant 

differences may be expected for a conventional locomotive-led train colliding with another 

conventional locomotive-led train than for a conventional locomotive-led train colliding with a 

cab car-led train. Track route alignment can also significantly influence the consequences of a 

collision; the consequences of a head-on collision on tangent track may be expected to be 

significantly different from an oblique collision at a switch. Similarly, the consequences of a 

grade-crossing collision with a heavy highway truck are likely to be significantly different from a 

grade-crossing collision with an automobile. For all accident types, the collision speed can also 

profoundly influence the consequences of the collision. Categorizing the accidents facilitates

calculation of the likelihood of an accident within a collision category as well as the 

development of strategies for protecting the occupants for accidents in that collision category.

This appendix describes one accident in each of the categories to illustrate the types of threats

that crashworthiness features are intended to mitigate.

Collisions with another Train

Train-to-train collisions include collisions between a passenger train and a freight train, as well 

as collisions between a cab car-led train and a conventional locomotive-led train.

The Glendale Incident

Figure A1 shows a photograph of the incident that occurred in Glendale, CA, on January 26, 

2005. Eight of the 11 fatalities occurred in Metrolink train 100, the southbound cab car-led 

passenger train. Three of the fatalities occurred in train 901, the northbound conventional 

locomotive-led passenger train. The trailing cab car from train 901 is on its side, shown in the 

middle right side of the photograph. This incident was investigated by several of the authors, as 

part of FRA‘s ongoing field study of injuries and fatalities in passenger train accidents [12].
119

Figure A1. Aerial Photograph of Glendale Incident

Train 100, traveling south at 62 mph, collided with a sport utility vehicle (SUV), which was 

situated perpendicular to the track with its front wheels between the rails. This impact occurred 

approximately 150 feet southeast of the grade crossing at Chevy Chase Drive. The SUV was 

lower than it would have been at a grade crossing, with the wheels of the SUV on the ties and 

ballast, below the running surface of the rails. This situation made it easier for some part of the 

SUV to get under the cab car and derail it. The Glendale incident involved three collisions:

1. The initial collision of train 100 with the SUV. Some part of the SUV–the 

engine block, transmission, differential, or other solid piece–became trapped 

under the cab car. The cab car then encountered special track work–switch 

components. The solid piece from the SUV interacted with the switch 

components in such a way that the front end of the cab car entered a siding. 

The back end of the cab car and the trailing equipment remained on the 

mainline track. These events led to:

a) A collision of train 100 with the freight train parked in the siding. The front of 

the cab car impacted a six-axle freight locomotive coupled to a second sixaxle freight locomotive in turn coupled to a number of cars loaded with 

ballast. The impact with the freight locomotive crushed the front end of the 

cab car, shortening the cab car by more than 26 feet. Before impact with the 

locomotive, the cab car was skewed. The lead truck of the cab car derailed and 

was guided by the rails of the siding track into the freight locomotive. The 

rear truck of the cab car appears to have stayed on the mainline track so that 

the cab car was traveling with the front on one track and the back on another 

track. The impact with the freight locomotive appears to have caused the back 
120

of the cab car to derail and swing out further into the right-of-way of the 

adjacent second mainline track. These events led to:

b) A raking collision of trains 100 and 901. As the back end of train 100‘s cab 

car swung around, it struck the side of train 901, which was traveling north at 

51 mph. The back end of train 100‘s cab car and the front end of train 100‘s 

first trailer car first impacted the side of train 901‘s middle passenger car, and 

proceeded to rake down the side of train 901.

Metrolink, a commuter rail authority in Los Angeles, CA, was preparing to purchase new 

equipment at the time of this fatal incident in Glendale. As part of its response to the incident, 

Metrolink decided to incorporate recent results of the Volpe Center‘s passenger train 

crashworthiness research to its ongoing procurement. In coordination with APTA, Metrolink 

approached FRA and the Federal Transit Administration (FTA) to develop design specifications. 

In turn, FRA and FTA formed the ad hoc Crash Energy Management Working Group in May 

2005. This working group included government engineers and participants from the rail industry, 

including passenger railroads, suppliers, labor organizations, and industry consultants. The 

working group developed a detailed technical specification for crush zones in passenger cars for 

Metrolink to include in its procurement specifications, as well as for other passenger railroads to 

include in future procurements of their own. The specification is a guide to using CEM 

technology.

Metrolink released its specification in September 2005, as part of an invitation for bid. In May 

2006, the award was made to Rotem, a division of Hyundai (now Hyundai Rotem Co.), that 

manufactures rail equipment. FRA and the Volpe Center are continuing to work with Metrolink, 

to help assure that the supplier meets the requirements. The first new equipment with these CEM 

features was delivered to Metrolink in March 2010 and was put into service by December 2010.

Collisions with Objects

The category of Collisions with Objects includes any collision between a train and something 

other than another train, such as a collision with a highway vehicle at a grade-crossing, as well as 

a collision with a displaced intermodal trailer fouling the right-of-way.

On June 18, 1998, a cab car-led, two-car MU commuter train collided with a highway truck that 

had become immobilized at a grade-crossing in Portage, IN. The highway truck consisted of a 

tractor with two trailers. The trailers were loaded with coils of sheet steel. The second trailer, the 

one farthest from the tractor, was stopped on the tracks. The train collided with the second 

trailer, and during the impact, a coil of steel broke free and punctured the end of the cab car. The 

train was traveling at a speed between 69 and 109 kilometers per hour (43 and 68 mph) when it 

hit the highway truck. As a result of the collision, three people were killed: a deadheading 

railroad employee and two passengers. The initial conditions of the accident are shown 

schematically in Figure A2.
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Figure A2. Schematic Drawing of Portage, IN, Grade Crossing Collision

Figure A3 shows postaccident photographs of the cab car, the highway truck trailer, and the coil 

of steel. The coil of steel weighed approximately 178 kN (40 kip) and was approximately 1.8 

meters (6 feet) in diameter. It received little damage during the collision. The height of the floor 

of the trailer was several inches below the height of the floor of the cab car. Because of the shape 

of the coil, it moved upward when it hit the end of the cab car. As shown in the photograph, the 

coil of steel punctured the end of the cab car. The coil stopped inside the cab car after traveling 

about half the car‘s length, destroying about one-quarter of the passenger seats in the car.

Figure A3. Postcollision Photographs of Cab Car, Truck Trailer, and Steel Coil Involved in 

Portage, IN, Grade Crossing Collision
122

Single Train Events

Single train events such as derailments can result in cars rolling on their sides or roofs. Such 

events are not generally associated with significant structural damage to the cars or loss of 

occupied volume due to structural crushing of the cars. Derailments can be associated with a 

large number of injuries and, often depending on the postderailment conditions, fatalities. 

Injuries such as those that have occurred during derailments can be mitigated with occupant 

protection measures.

On April 18, 2002, Amtrak Auto Train P052-18 derailed 21 of 40 cars on the CSXT near 

Crescent City, FL. The train was made up of 2 locomotives, 16 passenger cars, and 24 freight 

cars used for the transport of automobiles. The train was carrying 413 passengers and 33 Amtrak 

crewmembers. The train was traversing a left-hand curve at about 56 mph when the derailment 

occurred. As a result of the derailment, there were 4 fatalities, 36 serious injuries, and 106 minor 

injuries. Three fatalities were due to ejection through windows of the derailed cars. The fourth 

fatality was also due to ejection, but investigators were unable to determine where in the train the 

passenger was located at the time of derailment. The passenger may have been walking between 

cars when the train derailed.

Figure A4 shows an aerial view of the train postderailment. The two lead locomotive units and 

first two passengers cars remained upright and on the tracks. The 3rd through 23rd cars derailed, 

16 of which were Amtrak Superliner passenger cars. Figure A6 shows the first derailed car in the 

train. The coupled connections remained attached between the first six derailed passenger cars. 

Figure A4. Aerial View of Crescent City Derailment on April 18, 2002 (from NTSB report)
123

Figure A5 shows a photograph of the seventh passenger car as it is being uprighted. Two of the 

fatally injured passengers were in this car. As can be seen in the figure, most of the windows are 

not properly in their frames. Most of the windows appear to have been pushed in after the car 

derailed. There are scuffs and scrapes on the side of the car that suggest it slid some distance on 

its side. With the frames open, the ground would have been moving past the windows as the car 

slid. One potential mechanism for ejection is that a hand or a foot touched the ground, and the 

passenger was thereby pulled out of the car as it continued to slide.

Figure A5. Seventh Passenger Car, Uprighted

Figure A6 shows a photograph of the third passenger car. The couplers at both ends are intact 

and coupled up with the adjacent cars. Note also that all of the trucks visible are attached. None 

of the trucks became detached in this accident.
124

Figure A6. View of First Derailed Passenger Car Looking toward Lead End of Train

The photographs in Figure A7 show closeup views of the couplers at the lead and trailing end of 

the first derailed passenger car. The couplers can rotate to a significant angle—on the order of 30 

degrees—before they are constrained by the support structure. The car is kept from tipping at 

least in part by the coupler at the leading end of the car, whereas the coupler at the trailing end is 

acting to roll the car over.

Figure A7. Closeup Views of the Couplers of the First Derailed Passenger Car

Figure A8 shows a photograph of a transition area in the train. The leading cars shown on the left 

are derailed but in line with the track. The cars in the middle of the photograph are derailed, 

perpendicular to the track, and are stacked side-to-side. The coupler between the in-line section 

and the stacked section is broken. The couplers in the stacked section broke during the accident. 

Behind the stacked section is another part of the train—the automobile-carrying freight cars. 

None of the freight car couplers is broken. The first freight car is nether parallel nor 

perpendicular to the track. It is at an angle in between, something less than 45 degrees. The 

freight cars behind it are at progressively smaller angles until they come into line with the track.

Lead End

Trailing

End
125

Figure A8. View of Coupled Connection between Derailed Cars

Figure A9 shows the trailing end of the seventh passenger car. This is the last car to remain in 

line. The coupler shank broke inboard, close to where it is connected to the coupler head. Most 

of the failed couplers failed in this manner.

Figure A9. Trailing End of Seventh Passenger Car

Figure A10 shows the coupler between the last passenger car and the first auto car. The couplers 

from the seventh passenger car to the last passenger car were all broken. The mode of coupler 

failure is the same for most of the couplers and is shown Figure A9. None of the couplers 

between the freight cars appeared to break. The couplers used on the freight cars are the same 
126

design as used on the passenger cars. The loading condition shown in Figure A10 appears to be 

similar to the loading condition that caused the coupler failures.

Figure A10. Coupler between the Last Passenger Car and the First Auto Car
127

Appendix B. Selected CFR References

The following are terms defined in § 238.5 (Definitions) that are used within this report. The 

complete text of § 238.5 contains other definitions that are not used in this report.

§ 238.5 Definitions

Anti-climbing mechanism means the parts at the ends of adjoining vehicles in a train that are 

designed to engage when subjected to large buff loads to prevent the override of one vehicle by 

another.

Collision posts means structural members of the end structures of a vehicle that extend vertically 

from the underframe to which they are securely attached and that provide protection to occupied 

compartments from an object penetrating the vehicle during a collision.

Corner posts means structural members located at the intersection of the front or rear surface 

with the side surface of a rail vehicle and which extend vertically from the underframe to the 

roof. Corner posts may be combined with collision posts to become part of the end structure.

Crash energy management means an approach to the design of rail passenger equipment which 

controls the dissipation of energy during a collision to protect the occupied volumes from 

crushing and to limit the decelerations on passengers and crewmembers in those volumes. This 

may be accomplished by designing energy-absorbing structures of low strength in the 

unoccupied volumes of a rail vehicle or passenger train to collapse in a controlled manner, while 

providing higher structural strength in the occupied volumes. Energy deflection can also be part 

of a crash energy management approach. Crash energy management can be used to help provide 

anti-climbing resistance and to reduce the risk of train buckling during a collision.

Crewmember means a railroad employee called to perform service covered by the Federal hours 

of service laws at 49 U.S.C. 21103 and subject to the railroad‘s operating rules and program of 

operational tests and inspections required in § 217.9 and § 217.11 of this chapter.

Critical buckling stress means the minimum stress necessary to initiate buckling of a structural 

member.

End structure means the main support structure projecting upward from the underframe of a 

locomotive, passenger car, or other rail vehicle. The end structure is securely attached to the 

underframe at each end of a rail vehicle.

Fuel tank, external means a fuel containment vessel that extends outside the car body structure of 

a locomotive.

Fuel tank, internal means a fuel containment vessel that does not extend outside the car body 

structure of a locomotive.
128

Full-height collision post, corner post, or side frame post means any vertical framing member in 

the rail car body structure that spans the distance between the underframe and the roof at the car 

body section where the post is located. For collision posts located at the approximate third points 

laterally of an end frame, the term ―full-height‖ applies to posts that extend and connect to 

supporting structural members in the roof at the location of the posts, or to a beam connected to 

the top of the end-frame and supported by the roof rails (or anti-telescoping plate), or to both.

In passenger service/in revenue service means a train or passenger equipment that is carrying, or 

available to carry, passengers. Passengers need not have paid a fare in order for the equipment to 

be considered in passenger or in revenue service.

In service, when used in connection with passenger equipment, means:

(1) Passenger equipment subject to this part that is in passenger or revenue service in the United 

States; and

(2) All other passenger equipment subject to this part in the United States, unless the passenger 

equipment:

(i) Is being handled in accordance with §§ 238.15, 238.17, 238.305(d), or 238.503(f), as 

applicable;

(ii) Is in a repair shop or on a repair track;

(iii) Is on a storage track and is not carrying passengers; or

(iv) Has been delivered in interchange but has not been accepted by the receiving railroad.

Interior fitting means any component in the passenger compartment which is mounted to the 

floor, ceiling, sidewalls, or end walls and projects into the passenger compartment more than 

25 mm (1 in.) from the surface or surfaces to which it is mounted. Interior fittings do not include 

side and end walls, floors, door pockets, or ceiling lining materials, for example.

Lateral means the horizontal direction perpendicular to the direction of travel.

Locomotive means a piece of on-track rail equipment, other than hi-rail, specialized maintenance, 

or other similar equipment, which may consist of one or more units operated from a single 

control stand with one or more propelling motors designed for moving other passenger 

equipment; with one or more propelling motors designed to transport freight or passenger traffic, 

or both; or without propelling motors but with one or more control stands. This term does not 

include a locomotive propelled by steam power unless it is used to haul an intercity or commuter 

passenger train. Nor does this term include a freight locomotive when used to haul a passenger 

train due to failure of a passenger locomotive.

Locomotive cab means the compartment or space on board a locomotive where the control stand 

is located and which is normally occupied by the engineer when the locomotive is operated.
129

Locomotive, cab car means rail rolling equipment intended to provide transportation for 

members of the general public that is without propelling motors but equipped with one or more 

control stands.

Locomotive, MU means rail rolling equipment self-propelled by any power source and intended 

to provide transportation for members of the general public; however, this term does not include 

an MU locomotive propelled by steam power unless it is used to haul an intercity or commuter 

passenger train.

Longitudinal means in a direction parallel to the normal direction of travel.

95th-percentile adult male means, except as used in §238.447(f)(2), a person weighing 215 

pounds and possessing the following dimensions: erect sitting height: 38 inches; hip breadth 

(sitting): 16.5 inches; hip circumference (sitting): 47.2 inches; waist circumference (sitting): 42.5 

inches; chest depth: 10.5 inches; and chest circumference 44.5 inches.

Occupied volume means the volume of a rail vehicle or passenger train where passengers or 

crewmembers are normally located during service operation, such as the operating cab and 

passenger seating and sleeping areas. The entire width of a vehicle‘s end compartment that 

contains a control stand is an occupied volume. A vestibule is typically not considered occupied, 

except when it contains a control stand for use as a control cab.

Ordered, as applied to acquisition of equipment, means that the acquiring entity has given a 

notice to proceed to manufacture the equipment that represents a firm financial commitment to 

compensate the manufacturer for the contract price of the equipment or for damages if the order 

is nullified. Equipment is not ordered if future exercise of a contract option is required to place 

the remanufacturing process in motion.

Override means to climb over the normal coupling or side buffers and linking mechanism and 

impact the end of the adjoining rail vehicle or unit above the underframe.

Passenger car means rail rolling equipment intended to provide transportation for members of 

the general public and includes a self-propelled car designed to carry passengers, baggage, mail, 

or express. This term includes a passenger coach, cab car, and an MU locomotive. In the context 

of articulated equipment, ―passenger car‖ means that segment of the rail rolling equipment 

located between two trucks. This term does not include a private car.

Passenger coach means rail rolling equipment intended to provide transportation for members of 

the general public that is without propelling motors and without a control stand.

Passenger compartment means an area of a passenger car that consists of a seating area and any 

vestibule that is connected to the seating area by an open passageway.
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Passenger equipment—means

(1) All powered and unpowered passenger cars, locomotives used to haul a passenger car, and 

any other rail rolling equipment used in a train with one or more passenger cars. Passenger 

equipment includes—

(i) A passenger coach,

(ii) A cab car,

(iii) A MU locomotive,

(iv) A locomotive not intended to provide transportation for a member of the general public that 

is used to power a passenger train, and

(v) Any non-self-propelled vehicle used in a passenger train, including an express car, baggage 

car, mail car, freight car, or a private car.

(2) In the context of articulated equipment, ―passenger equipment‖ means a segment of rail 

rolling equipment located between two trucks that is used in a train with one or more passenger 

cars. This term does not include a freight locomotive when used to haul a passenger train due to 

failure of a passenger locomotive.

Permanent deformation means the undergoing of a permanent change in shape of a structural 

member of a rail vehicle.

Public highway-rail grade crossing means a location where a public highway, road or street, 

including associated sidewalks or pathways, crosses one or more active railroad tracks at grade.

Railroad means any form of nonhighway ground transportation that runs on rails or 

electromagnetic guideways and any entity providing such transportation, including—

(i) Commuter or other short-haul railroad passenger service in a metropolitan or suburban area 

and commuter railroad service that was operated by the Consolidated Rail Corporation on 

January 1, 1979; and

(ii) High speed ground transportation systems that connect metropolitan areas, without regard to 

whether those systems use new technologies not associated with traditional railroads; but does 

not include rapid transit operations in an urban area that are not connected to the general railroad 

system of transportation.

Rollover strength means the strength provided to protect the structural integrity of a rail vehicle 

in the event the vehicle leaves the track and impacts the ground on its side or roof.

Roof rail means the longitudinal structural member at the intersection of the side wall and the 

roof sheathing.
131

Seating area means an area of a passenger car that normally contains passenger seating.

Semi-permanently coupled means coupled by means of a drawbar or other coupling mechanism 

that requires tools to perform the uncoupling operation. Coupling and uncoupling of each semipermanently coupled unit in a train can be performed safely only while at a maintenance or shop 

location where personnel can safely get under a unit or between units.

Semi-monocoque means a type of rail vehicle construction where the shell or skin acts as a single 

unit with the supporting frame to resist and transmit the loads acting on the rail vehicle.

Shear strength means the ability of a structural member to resist forces or components of forces 

acting perpendicular to compression or tension forces, or both, in the member.

Side posts means main vertical structural elements in the sides of a rail vehicle.

Side sill means that portion of the underframe or side at the bottom of the rail vehicle side wall.

Skin means the outer covering of a fuel tank and a rail vehicle. The skin may be covered with 

another coating of material such as fiberglass.

Telescope means override an adjoining rail vehicle or unit and penetrate into the interior of that 

adjoining vehicle or unit because of compressive forces.

Tier I means operating at speeds not exceeding 125 mph.

Tier II means operating at speeds exceeding 125 mph but not exceeding 150 mph.

Trailer car means a rail vehicle that neither propels a Tier II passenger train nor is the leading 

unit in a Tier II passenger train. A trailer car is normally without a control stand and is normally 

occupied by passengers.

Train means a locomotive unit or locomotive units coupled, with or without cars. For the 

purposes of the provisions of this part related to power brakes, the term ―train‖ does not include 

such equipment when being used in switching service.

Train, commuter means a passenger train providing commuter service within an urban, suburban, 

or metropolitan area. The term includes a passenger train provided by an instrumentality of a 

State or a political subdivision of a State.

Train, passenger means a train that transports or is available to transport members of the general 

public. If a train is composed of a mixture of passenger and freight equipment, that train is a 

passenger train for purposes of this part.

Trainset, passenger means a passenger train.

Transverse means in a direction perpendicular to the normal direction of travel.
132

Ultimate strength means the load at which a structural member fractures or ceases to resist any 

load.

Underframe means the lower horizontal support structure of a rail vehicle.

Unit means passenger equipment of any type, except a freight locomotive when used to haul a 

passenger train due to failure of a passenger locomotive.

Unoccupied volume means the volume of a rail vehicle or passenger train which does not contain 

seating and is not normally occupied by passengers or crewmembers.

Vehicle, rail means passenger equipment of any type and includes a car, trailer car, locomotive, 

power car, tender, or similar vehicle. This term does not include a freight locomotive when used 

to haul a passenger train due to failure of a passenger locomotive.

Vestibule means an area of a passenger car that normally does not contain seating and is used in 

passing from the seating area to the side exit doors.

Yield strength means the ability of a structural member to resist a change in length caused by a 

heavy load. Exceeding the yield strength may cause permanent deformation of the member.

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§ 238.111 Pre-revenue service acceptance testing plan.

(a) Passenger equipment that has previously been used in revenue service in the United States. 

For passenger equipment that has previously been used in revenue service in the United States, 

each railroad shall test the equipment on its system prior to placing such equipment in revenue 

service for the first time on its railroad to ensure the compatibility of the equipment with the 

railroad's operating system (including the track, and signal system). A description of such testing 

shall be retained by the railroad and made available to FRA for inspection and copying upon 

request. For purposes of this paragraph, passenger equipment that has previously been used in 

revenue service in the United States means:

(1) The actual equipment used in such service;

(2) Equipment manufactured identically to that actual equipment; and

(3) Equipment manufactured similarly to that actual equipment with no material differences in 

safety-critical components or systems.

(b) Passenger equipment that has not been used in revenue service in the United States. Before 

using passenger equipment for the first time on its system that has not been used in revenue 

service in the United States, each railroad shall:

(1) Prepare a pre-revenue service acceptance testing plan for the equipment which contains the 

following elements:
133

(i) An identification of any waivers of FRA or other Federal safety regulations required for the 

testing or for revenue service operation of the equipment;

(ii) A clear statement of the test objectives. One of the principal test objectives shall be to 

demonstrate that the equipment meets the safety requirements specified in this part when 

operated in the environment in which it is to be used;

(iii) A planned schedule for conducting the testing;

(iv) A description of the railroad property or facilities to be used to conduct the testing;

(v) A detailed description of how the testing is to be conducted, including a description of the 

criteria to be used to evaluate the equipment's performance;

(vi) A description of how the test results are to be recorded;

(vii) A description of any special instrumentation to be used during the tests;

(viii) A description of the information or data to be obtained;

(ix) A description of how the information or data obtained is to be analyzed or used;

(x) A description of any criteria to be used as safety limits during the testing;

(xi) A description of the criteria to be used to measure or determine the success or failure of the 

tests. If acceptance is to be based on extrapolation of less than full-level testing results, the 

analysis to be done to justify the validity of the extrapolation shall be described;

(xii) Quality control procedures to ensure that the inspection, testing, and maintenance 

procedures are followed;

(xiii) Criteria to be used for the revenue service operation of the equipment; and

(xiv) A description of any testing of the equipment that has previously been performed.

(2) Submit a copy of the plan to FRA at least 30 days prior to testing the equipment and include 

with that submission notification of the times and places of the pre-revenue service tests to 

permit FRA observation of such tests. For Tier II passenger equipment, the railroad shall obtain 

FRA approval of the plan under the procedures specified in § 238.21.

(3) Comply with the plan, including fully executing the tests required by the plan.

(4) Document in writing the results of the tests. For Tier II passenger equipment, the railroad 

shall report the results of the tests to the FRA Associate Administrator for Safety at least 90 days 

prior to its intended operation of the equipment in revenue service.
134

(5) Correct any safety deficiencies identified in the design of the equipment or in the inspection, 

testing, and maintenance procedures, uncovered during the testing. If safety deficiencies cannot 

be corrected by design changes, the railroad shall impose operational limitations on the revenue 

service operation of the equipment that are designed to ensure that the equipment can operate 

safely. For Tier II passenger equipment, the railroad shall comply with any operational 

limitations imposed by the FRA Associate Administrator for Safety on the revenue service 

operation of the equipment for cause stated following FRA review of the results of the test 

program. This section does not restrict a railroad from petitioning FRA for a waiver of a safety 

regulation under the procedures specified in part 211 of this chapter.

(6) Make the plan and documentation kept pursuant to that plan available for inspection and 

copying by FRA upon request.

(7) For Tier II passenger equipment, obtain approval from the FRA Associate Administrator for 

Safety prior to placing the equipment in revenue service. The Associate Administrator grants 

such approval upon a showing of the railroad's compliance with the applicable requirements of 

this part.

(c) If a railroad plans a major upgrade or introduction of new technology on Tier II passenger 

equipment that has been used in revenue service in the United States and that affects a safety 

system on such equipment, the railroad shall follow the procedures specified in paragraph (b) of 

this section prior to placing the equipment in revenue service with such a major upgrade or 

introduction of new technology.

******************************************************************************

§ 238.203. Static end strength.

(a)(1) Except as further specified in this paragraph or in paragraph (d), on or after November 8, 

1999 all passenger equipment shall resist a minimum static end load of 800,000 pounds applied 

on the line of draft without permanent deformation of the body structure.

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§ 238.205. Anti-climbing mechanism.

(a) Except as provided in paragraph (b) of this section, all passenger equipment placed in service 

for the first time on or after September 8, 2000, and prior to March 9, 2010, shall have at both the 

forward and rear ends an anti-climbing mechanism capable of resisting an upward or downward

vertical force of 100,000 pounds without failure. All passenger equipment placed in service for 

the first time on or after March 9, 2010, shall have at both the forward and rear ends an anticlimbing mechanism capable of resisting an upward or downward vertical force of 100,000 

pounds without permanent deformation. When coupled together in any combination to join two 

vehicles, AAR Type H and Type F tight-lock couplers satisfy the requirements of this paragraph 

(a).

******************************************************************************

§ 238.207. Link between coupling mechanism and car body.

All passenger equipment placed in service for the first time on or after September 8, 2000 shall 

have a coupler carrier at each end designed to resist a vertical downward thrust from the coupler 
135

shank of 100,000 pounds for any normal horizontal position of the coupler, without permanent 

deformation. For passenger equipment that is connected by articulated joints that comply with 

the requirements of § 238.205(a), such passenger equipment also complies with the requirements 

of this section.

******************************************************************************

§ 238.209. Forward end structure of locomotives, including cab cars and MU locomotives.

(a)(1) The skin covering the forward-facing end of each locomotive, including a cab car and an 

MU locomotive, shall be:

(i) Equivalent to a 1/2-inch steel plate with a yield strength of 25,000 pounds-per-squareinch--material of a higher yield strength may be used to decrease the required thickness of 

the material provided at least an equivalent level of strength is maintained;

(ii) Designed to inhibit the entry of fluids into the occupied cab area of the equipment; and

(iii) Affixed to the collision posts or other main vertical structural members of the forward 

end structure so as to add to the strength of the end structure.

(2) As used in this paragraph (a), the term ―skin‖ does not include forward-facing windows and 

doors.

(b) The forward end structure of a cab car or an MU locomotive may comply with the 

requirements of Appendix F to this part in lieu of the requirements of either § 238.211 (Collision 

posts) or § 238.213 (Corner posts), or both, provided that the end structure is designed to protect 

the occupied volume for its full height, from the underframe to the anti-telescoping plate (if 

used) or roof rails.

******************************************************************************

§ 238.211. Collision posts.

(a) Except as further specified in this paragraph, paragraphs (b) through (d) of this section, and § 

238.209(b)—

(1) All passenger equipment placed in service for the first time on or after September 8, 2000, 

shall have either:

(i) Two full-height collision posts, located at approximately the one-third points laterally, at each 

end. Each collision post shall have an ultimate longitudinal shear strength of not less than 

300,000 pounds at a point even with the top of the underframe member to which it is attached. If 

reinforcement is used to provide the shear value, the reinforcement shall have full value for a 

distance of 18 inches up from the underframe connection and then taper to a point approximately 

30 inches above the underframe connection; or
136

(ii) An equivalent end structure that can withstand the sum of forces that each collision post in 

paragraph (a)(1)(i) of this section is required to withstand. For analysis purposes, the required 

forces may be assumed to be evenly distributed at the end structure at the underframe joint.

(2) The requirements of this paragraph (a) do not apply to unoccupied passenger equipment 

operating in a passenger train, or to the rear end of a locomotive if the end is unoccupied by 

design.

(b) Except for a locomotive that is constructed on or after January 1, 2009, and is subject to the 

requirements of subpart D of part 229 of this chapter, each locomotive, including a cab car and 

an MU locomotive, ordered on or after September 8, 2000, or placed in service for the first time 

on or after September 9, 2002, shall have at its forward end, in lieu of the structural protection 

described in paragraph (a) of this section, either:

(1) Two forward collision posts, located at approximately the one-third points laterally, each 

capable of withstanding:

(i) A 500,000-pound longitudinal force at the point even with the top of the underframe, without 

exceeding the ultimate strength of the joint; and

(ii) A 200,000-pound longitudinal force exerted 30 inches above the joint of the post to the 

underframe, without exceeding the ultimate strength; or

(2) An equivalent end structure that can withstand the sum of the forces that each collision post 

in paragraph (b)(1) of this section is required to withstand.

(c)(1) Each cab car and MU locomotive ordered on or after May 10, 2010, or placed in service 

for the first time on or after March 8, 2012, shall have at its forward end, in lieu of the structural 

protection described in paragraphs (a) and (b) of this section, two forward collision posts, located 

at approximately the one-third points laterally, meeting the requirements set forth in paragraphs 

(c)(2) and (c)(3) of this section:

(2) Each collision post acting together with its supporting car body structure shall be capable of 

withstanding the following loads individually applied at any angle within 15 degrees of the 

longitudinal axis:

(i) A 500,000-pound horizontal force applied at a point even with the top of the underframe, 

without exceeding the ultimate strength of either the post or its supporting car body structure;

(ii) A 200,000-pound horizontal force applied at a point 30 inches above the top of the 

underframe, without exceeding the ultimate strength of either the post or its supporting car body 

structure; and

(iii) A 60,000-pound horizontal force applied at any height along the post above the top of the 

underframe, without permanent deformation of either the post or its supporting car body 

structure.
137

(3) Prior to or during structural deformation, each collision post acting together with its 

supporting car body structure shall be capable of absorbing a minimum of 135,000 foot-pounds 

of energy (0.18 megajoule) with no more than 10 inches of longitudinal, permanent deformation 

into the occupied volume, in accordance with the following:

(i) The collision post shall be loaded longitudinally at a height of 30 inches above the top of the 

underframe;

(ii) The load shall be applied with a fixture, or its equivalent, having a width sufficient to 

distribute the load directly into the webs of the post, but of no more than 36 inches, and either:

(A) A flat plate with a height of 6 inches; or

(B) A curved surface with a diameter of no more than 48 inches; and

(iii) There shall be no complete separation of the post, its connection to the underframe, its 

connection to either the roof structure or anti-telescoping plate (if used), or of its supporting car 

body structure.

(d) The end structure requirements of this section apply only to the ends of a semi-permanently 

coupled consist of articulated units, provided that:

(1) The railroad submits to FRA under the procedures specified in § 238.21 a documented 

engineering analysis establishing that the articulated connection is capable of preventing 

disengagement and telescoping to the same extent as equipment satisfying the anti-climbing and 

collision post requirements contained in this subpart; and

(2) FRA finds the analysis persuasive.

******************************************************************************

§ 238.213. Corner posts.

(a)(1) Except as further specified in paragraphs (b) and (c) of this section and § 238.209(b), each 

passenger car shall have at each end of the car, placed ahead of the occupied volume, two full 

height corner posts, each capable of resisting together with its supporting car body structure:

(i) A 150,000-pound horizontal force applied at a point even with the top of the underframe, 

without exceeding the ultimate strength of either the post or its supporting car body structure;

(ii) A 20,000-pound horizontal force applied at the point of attachment to the roof structure, 

without exceeding the ultimate strength of either the post or its supporting car body structure; 

and

(iii) A 30,000-pound horizontal force applied at a point 18 inches above the top of the 

underframe, without permanent deformation of either the post or its supporting car body 

structure.
138

(2) For purposes of this paragraph (a), the orientation of the applied horizontal forces shall range 

from longitudinal inward to lateral inward.

(b)(1) Except as provided in paragraph (c) of this section, each cab car and MU locomotive 

ordered on or after May 10, 2010, or placed in service for the first time on or after March 8, 

2012, shall have at its forward end, in lieu of the structural protection described in paragraph (a) 

of this section, two corner posts ahead of the occupied volume, meeting all of the requirements 

set forth in paragraphs (b)(2) and (b)(3) of this section:

(2) Each corner post acting together with its supporting car body structure shall be capable of 

withstanding the following loads individually applied toward the inside of the vehicle at all 

angles in the range from longitudinal to lateral:

(i) A 300,000-pound horizontal force applied at a point even with the top of the underframe, 

without exceeding the ultimate strength of either the post or its supporting car body structure;

(ii) A 100,000-pound horizontal force applied at a point 18 inches above the top of the 

underframe, without permanent deformation of either the post or its supporting car body 

structure; and

(iii) A 45,000-pound horizontal force applied at any height along the post above the top of the 

underframe, without permanent deformation of either the post or its supporting car body 

structure.

(3) Prior to or during structural deformation, each corner post acting together with its supporting 

car body structure shall be capable of absorbing a minimum of 120,000 foot-pounds of energy 

(0.16 megajoule) with no more than 10 inches of longitudinal, permanent deformation into the 

occupied volume, in accordance with the following:

(i) The corner post shall be loaded longitudinally at a height of 30 inches above the top of the 

underframe;

(ii) The load shall be applied with a fixture, or its equivalent, having a width sufficient to 

distribute the load directly into the webs of the post, but of no more than 36 inches and either:

(A) A flat plate with a height of 6 inches; or

(B) A curved surface with a diameter of no more than 48 inches; and

(iii) There shall be no complete separation of the post, its connection to the underframe, its 

connection to either the roof structure or anti-telescoping plate (if used), or of its supporting car 

body structure.

(c)(1) Each cab car and MU locomotive ordered on or after May 10, 2010, or placed in service 

for the first time on or after March 8, 2012, utilizing low-level passenger boarding on the non-
139

operating side of the cab end shall meet the corner post requirements of paragraph (b) of this 

section for the corner post on the side of the cab containing the control stand. In lieu of the 

requirements of paragraph (b) of this section, and after FRA review and approval of a plan, 

including acceptance criteria, to evaluate compliance with this paragraph (c), each such cab car 

and MU locomotive may have two corner posts on the opposite (non-operating) side of the cab 

from the control stand meeting all of the requirements set forth in paragraphs (c)(2) through 

(c)(4) of this section:

(2) One corner post shall be located ahead of the stepwell and, acting together with its supporting 

car body structure, shall be capable of withstanding the following horizontal loads individually 

applied toward the inside of the vehicle:

(i) A 150,000-pound longitudinal force applied at a point even with the top of the underframe, 

without exceeding the ultimate strength of either the post or its supporting car body structure;

(ii) A 30,000-pound longitudinal force applied at a point 18 inches above the top of the 

underframe, without permanent deformation of either the post or its supporting car body 

structure;

(iii) A 30,000-pound longitudinal force applied at the point of attachment to the roof structure, 

without permanent deformation of either the post or its supporting car body structure;

(iv) A 20,000-pound longitudinal force applied at any height along the post above the top of the 

underframe, without permanent deformation of either the post or its supporting car body 

structure;

(v) A 300,000-pound lateral force applied at a point even with the top of the underframe, without 

exceeding the ultimate strength of either the post or its supporting car body structure;

(vi) A 100,000-pound lateral force applied at a point 18 inches above the top of underframe, 

without permanent deformation of either the post or its supporting car body structure; and

(vii) A 45,000-pound lateral force applied at any height along the post above the top of the 

underframe, without permanent deformation of either the post or its supporting car body 

structure.

(3) A second corner post shall be located behind the stepwell and, acting together with its 

supporting car body structure, shall be capable of withstanding the following horizontal loads 

individually applied toward the inside of the vehicle:

(i) A 300,000-pound longitudinal force applied at a point even with the top of the underframe,

without exceeding the ultimate strength of either the post or its supporting car body structure;

(ii) A 100,000-pound longitudinal force applied at a point 18 inches above the top of the 

underframe, without permanent deformation of either the post or its supporting car 

bodystructure;
140

(iii) A 45,000-pound longitudinal force applied at any height along the post above the top of the 

underframe, without permanent deformation of either the post or its supporting car body 

structure;

(iv) A 100,000-pound lateral force applied at a point even with the top of the underframe, 

without exceeding the ultimate strength of either the post or its supporting car body structure;

(v) A 30,000-pound lateral force applied at a point 18 inches above the top of the underframe, 

without permanent deformation of either the post or its supporting car body structure; and

(vi) A 20,000-pound lateral force applied at any height along the post above the top of the 

underframe, without permanent deformation of body structure.

(4) Prior to or during structural deformation, the two posts in combination acting together with 

their supporting body structure shall be capable of absorbing a minimum of 120,000 foot-pounds 

of energy (0.16 megajoule) in accordance with the following:

(i) The corner posts shall be loaded longitudinally at a height of 30 inches above the top of the 

underframe;

(ii) The load shall be applied with a fixture, or its equivalent, having a width sufficient to 

distribute the load directly into the webs of the post, but of no more than 36 inches and either:

(A) A flat plate with a height of 6 inches; or

(B) A curved surface with a diameter of no more than 48 inches; and

(iii) The corner post located behind the stepwell shall have no more than 10 inches of 

longitudinal, permanent deformation. There shall be no complete separation of the corner post 

located behind the stepwell, its connection to the underframe, its connection to either the roof 

structure or anti-telescoping plate (if used), or of its supporting car body structure. The corner 

post ahead of the stepwell is permitted to fail. (A graphical description of the forward end of a 

cab car or an MU locomotive utilizing low-level passenger boarding on the non-operating side of 

the cab end is provided in Figure 1 to subpart C of this part.)

******************************************************************************

§ 238.215. Rollover strength.

(a) Each passenger car shall be designed to rest on its side and be uniformly supported at the top 

( ̳ ̳roof rail‘‘), the bottom cords ( ̳ ̳side sill‘‘) of the side frame, and, if bi-level, the intermediate 

floor rail. The allowable stress in the structural members of the occupied volumes for this 

condition shall be one-half yield or one-half the critical buckling stress, whichever is less. Local 

yielding to the outer skin of the passenger car is allowed provided that the resulting deformations 

in no way intrude upon the occupied volume of the car.
141

(b) Each passenger car shall also be designed to rest on its roof so that any damage in occupied 

areas is limited to roof sheathing and framing. Other than roof sheathing and framing, the 

allowable stress in the structural members of the occupied volumes for this condition shall be 

one-half yield or one-half the critical buckling stress, whichever is less. Deformation to the roof 

sheathing and framing is allowed to the extent necessary to permit the vehicle to be supported 

directly on the top chords of the side frames and end frames.

******************************************************************************

§ 238.217. Side structure.

Each passenger car shall comply with the following:

(a) Side posts and corner braces. (1) For modified girder, semimonocoque, or truss construction, 

the sum of the section moduli in inches 3— about a longitudinal axis, taken at the weakest 

horizontal section between the side sill and side plate—of all posts and braces on each side of the 

car located between the body corner posts shall be not less than 0.30 multiplied by the distance in 

feet between the centers of end panels.

(2) For modified girder or semimonocoque construction only, the sum of the section moduli in 

inches 3—about a transverse axis, taken at the weakest horizontal section between the side sill 

and side plate—of all posts, braces and pier panels, to the extent available, on each side of the 

car located between body corner posts shall be not less than 0.20 multiplied by the distance in 

feet between the centers of end panels.

(3) The center of an end panel is the point midway between the center of the body corner post 

and the center of the adjacent side post.

(4) The minimum section moduli or thicknesses specified in paragraph (a) of this section may be 

adjusted in proportion to the ratio of the yield strength of the material used to that of mild openhearth steel for a car whose structural members are made of a higher strength steel.

(b) Sheathing. (1) Outside sheathing of mild, open-hearth steel when used flat, without 

reinforcement (other than side posts) in a side frame of modified girder or semimonocoque 

construction shall not be less than 1/8 inch nominal thickness. Other metals may be used of a 

thickness in inverse proportion to their yield strengths.

(2) Outside metal sheathing of less than 1/8-inch thickness may be used only if it is reinforced so 

as to produce at least an equivalent sectional area at a right angle to reinforcements as that of the 

flat sheathing specified in paragraph (b)(1) of this section.

(3) When the sheathing used for truss construction serves no load-carrying function, the 

minimum thickness of that sheathing shall be not less than 40 percent of that specified in 

paragraph (b)(1) of this section.

******************************************************************************
142

§ 238.219. Truck-to-car-body attachment.

Passenger equipment shall have a truck-to-car-body attachment with an ultimate strength 

sufficient to resist without failure the following individually applied loads: 2g vertically on the 

mass of the truck; and 250,000 pounds in any horizontal direction on the truck, along with the 

resulting vertical reaction to this load. For purposes of this section, the mass of the truck includes 

axles, wheels, bearings, the truck-mounted brake system, suspension system components, and 

any other component attached to the truck by design.

******************************************************************************

§ 238.233. Interior fittings and surfaces.

(a) Each seat in a passenger car shall—

(1) Be securely fastened to the car body so as to withstand an individually applied acceleration of 

4g acting in the lateral direction and 4g acting in the upward vertical direction on the deadweight 

of the seat or seats, if held in tandem; and

(2) Have an attachment to the car body of an ultimate strength capable of resisting 

simultaneously:

(i) The longitudinal inertial force of 8g acting on the mass of the seat; and

(ii) The load associated with the impact into the seatback of an unrestrained 95th-percentile adult 

male initially seated behind the seat, when the floor to which the seat is attached decelerates with 

a triangular crash pulse having a peak of 8g and a duration of 250 milliseconds.

(b) Overhead storage racks in a passenger car shall provide longitudinal and lateral restraint for 

stowed articles. Overhead storage racks shall be attached to the car body with sufficient strength 

to resist loads due to the following individually applied accelerations acting on the mass of the 

luggage stowed as determined by the railroad:

(1) Longitudinal: 8g;

(2) Vertical: 4g; and

(3) Lateral: 4g.

(c) Other interior fittings within a passenger car shall be attached to the car body with sufficient 

strength to withstand the following individually applied accelerations acting on the mass of the 

fitting:

(1) Longitudinal: 8g;

(2) Vertical: 4g; and

(3) Lateral: 4g.

(d) To the extent possible, all interior fittings in a passenger car, except seats, shall be recessed or 

flush-mounted.

(e) Sharp edges and corners in a locomotive cab and a passenger car shall be either avoided or 

padded to mitigate the consequences of an impact with such surfaces.
143

(f) Each seat provided for a crewmember regularly assigned to occupy the cab of a locomotive 

and each floor-mounted seat in the cab shall be secured to the car body with an attachment 

having an ultimate strength capable of withstanding the loads due to the following individually 

applied accelerations acting on the combined mass of the seat and a 95th-percentile adult male 

occupying it:

(1) Longitudinal: 8g;

(2) Lateral: 4g; and

(3) Vertical: 4g.

(g) If, for purposes of showing compliance with the requirements of this section, the strength of a 

seat attachment is to be demonstrated through sled testing, the seat structure and seat attachment 

to the sled that is used in such testing must be representative of the actual seat structure in, and 

seat attachment to, the rail vehicle subject to the requirements of this section. If the attachment 

strength of any other interior fitting is to be demonstrated through sled testing, for purposes of 

showing compliance with the requirements of this section, such testing shall be conducted in a 

similar manner.

******************************************************************************

Included by reference:

APTA SS-C&S-006-98, Rev. 1,

Standard for Attachment Strength of Interior Fittings for Passenger Railroad Equipment

APTA SS-C&S-034-99, Rev. 2 .

Standard for the Design and Construction of Passenger Railroad Rolling Stock

******************************************************************************

Appendix F to Part 238—Alternative Dynamic Performance Requirements for Front End 

Structures of Cab Cars and MU Locomotives

As specified in § 238.209(b), the forward end of a cab car or an MU locomotive may comply 

with the requirements of this appendix in lieu of the requirements of either § 238.211 (Collision 

posts) or § 238.213 (Corner posts), or both. The requirements of this appendix are intended to be 

equivalent to the requirements of those sections and allow for the application of dynamic 

performance criteria to cab cars and MU locomotives as an alternative to the requirements of 

those sections. The alternative dynamic performance requirements are applicable to all cab cars

and MU locomotives, and may in particular be helpful for evaluating the compliance of cab cars 

and MU locomotives with shaped noses or crash energy management designs, or both. In any 

case, the end structure must be designed to protect the occupied volume for its full height, from 

the underframe to the anti-telescoping plate (if used) or roof rails. The requirements of this 

appendix are provided only as alternatives to the requirements of §§ 238.211 and 238.213, not in 

addition to the requirements of those sections. Cab cars and MU locomotives are not required to 

comply with both the requirements of those sections and the requirements of this appendix, 

together.

Alternative Requirements for Collision Posts

(a)(1) In lieu of meeting the requirements of § 238.211, the front end frame acting together with 

its supporting car body structure shall be capable of absorbing a minimum of 135,000 foot-
144

pounds of energy (0.18 megajoule) prior to or during structural deformation by withstanding a 

frontal impact with a rigid object in accordance with all of the requirements set forth in 

paragraphs (a)(2) through (a)(4) of this appendix:

(2)(i) The striking surface of the object shall be centered at a height of 30 inches above the top of 

the underframe;

(ii) The striking surface of the object shall have a width of no more than 36 inches and a 

diameter of no more than 48 inches;

(iii) The center of the striking surface shall be offset by 19 inches laterally from the center of the 

cab car or MU locomotive, and on the weaker side of the end frame if the end frame‘s strength is 

not symmetrical; and

(iv) Only the striking surface of the object interacts with the end frame structure.

(3) As a result of the impact, there shall be no more than 10 inches of longitudinal, permanent 

deformation into the occupied volume. There shall also be no complete separation of the post, its 

connection to the underframe, its connection to either the roof structure or the anti-telescoping 

plate (if used), or of its supporting car body structure. (A graphical description of the frontal 

impact is provided in Figure 1 to this appendix.)

(4) The nominal weights of the object and the cab car or MU locomotive, as ballasted, and the 

speed of the object may be adjusted to impart the minimum of 135,000 footpounds of energy 

(0.18 megajoule) to be absorbed (Ea), in accordance with the following formula: Ea = E0 - Ef

Where:

E0 = Energy of initially moving object at impact = 1⁄2 m1*V02.

Ef = Energy after impact = 1⁄2 (m1 + m2)*Vf2.

V0 = Speed of initially moving object at impact.

Vf = Speed of both objects after collision = m1*V0/(m1 + m2).

m1 = Mass of initially moving object.

m2 = Mass of initially standing object.

(Figure 1 shows as an example a cab car or an MU locomotive having a weight of 100,000 

pounds and the impact object having a weight of 14,000 pounds, so that a minimum speed of 

18.2 mph would satisfy the collision-energy requirement.)

Alternative Requirements for Corner Posts

(b)(1) In lieu of meeting the requirements of § 238.213, the front end frame acting together with 

its supporting car body structure shall be capable of absorbing a minimum of 120,000 footpounds of energy (0.16 megajoule) prior to or during structural deformation by withstanding a 

frontal impact with a rigid object in accordance with all of the requirements set forth in 

paragraphs (b)(2) through (b)(4) of this appendix:

(2)(i) The striking surface of the object shall be centered at a height of 30 inches above the top of 

the underframe;
145

(ii) The striking surface of the object shall have a width of no more than 36 inches and a 

diameter of no more than 48 inches;

(iii) The center of the striking surface shall be aligned with the outboard edge of the cab car or 

MU locomotive, and on the weaker side of the end frame if the end frame‘s strength is not 

symmetrical; and

(iv) Only the striking surface of the object interacts with the end frame structure.

(3)(i) Except as provided in paragraph (b)(3)(ii) of this appendix, as a result of the impact, there 

shall be no more than 10 inches of longitudinal, permanent deformation into the occupied 

volume. There shall also be no complete separation of the post, its connection to the underframe, 

its connection to either the roof structure or the anti-telescoping plate (if used), or of its 

supporting car body structure. (A graphical description of the frontal impact is provided in 

Figure 2 to this appendix.); and

(ii) After FRA review and approval of a plan, including acceptance criteria, to evaluate 

compliance with this paragraph (b), cab cars and MU locomotives utilizing low-level passenger 

boarding on the non-operating side of the cab may have two, full-height corner posts on that side, 

one post located ahead of the stepwell and one located behind it, so that the corner post located 

ahead of the stepwell is permitted to fail provided that—

(A) The corner post located behind the stepwell shall have no more than 10 inches of 

longitudinal, permanent deformation; and

(B) There shall be no complete separation of that post, its connection to the underframe, its 

connection to either the roof structure or the anti-telescoping plate (if used), or of its supporting 

car body structure.

(4) The nominal weights of the object and the cab car or MU locomotive, as ballasted, and the 

speed of the object may be adjusted to impart the minimum of 120,000 foot-pounds of energy 

(0.16 megajoule) to be absorbed (Ea), in accordance with the following formula: Ea = E0 - Ef

Where:

E0 = Energy of initially moving object at impact = 1⁄2 m1*V02.

Ef = Energy after impact = 1⁄2 (m1 + m2)*Vf2.

V0 = Speed of initially moving object at impact.

Vf = Speed of both objects after collision = m1*V0/(m1 + m2).

m1 = Mass of initially moving object.

m2 = Mass of initially standing object.

(Figure 2 shows as an example a cab car or an MU locomotive having a weight of 100,000 

pounds and the impact object having a weight of 14,000 pounds, so that a minimum speed of 

17.1 mph would satisfy the collision-energy requirement.)
146

FIGURE 1 TO APPENDIX F OF PART 238–

EXAMPLE OF FORWARD END OF CAB CAR OR MU LOCOMOTIVE

AT IMPACT WITH PROXY OBJECT TO DEMONSTRATE COMPLIANCE WITH 

ALTERNATIVE, COLLISION POST PERFORMANCE STANDARD—

TOP AND SIDE VIEWS

‖ = inches.

lbs = pounds.

48” 

diameter

30”

36”

19”

18.2 mph

W = 100,000 lbs

W = 14,000 lbs

W = 100,000 lb 18.2 mph s

W = 14,000 lbs
147

FIGURE 2 TO APPENDIX F OF PART 238–

EXAMPLE OF FORWARD END OF CAB CAR OR MU LOCOMOTIVE

AT IMPACT WITH PROXY OBJECT TO DEMONSTRATE COMPLIANCE WITH 

ALTERNATIVE, CORNER POST PERFORMANCE STANDARD—

TOP AND SIDE VIEWS

‖ = inches.

lbs = pounds.

******************************************************************************

36”

17.1 mph

W = 100,000 lbs

W = 14,000 lbs

48” 

diameter

17.1 mph W = 100,000 lbs

W = 14,000 lbs
148

Appendix C. Locomotive and Passenger Car Input Data

This appendix contains force-crush characteristics for conventional passenger equipment for use 

in modeling the Collision Scenario. This appendix also contains input data for a rigid, halfsymmetric model of an F40-type locomotive. The input data were generated for use with the 

Abaqus/Explicit finite element code. 

Force-crush Characteristics for Conventional Equipment

Table A1 contains force-crush characteristics for the conventional passenger equipment. As 

defined in the Collision Scenario in Section 3.1, the moving train is made up of conventional 

passenger equipment. These data can be used to define spring characteristics in a lumpedparameter model of the moving train in the Collision Scenario. 

Table A1. Idealized Force-Crush Data for Conventional Equipment

Vehicle Crush (in) Force (lbf)

Conventional Passenger 

Car

0 0

3 80,000

6 2,500,000

Conventional Locomotive

0 0

2.5 100,000

5 2,500,000

Input Data for Rigid Locomotive

The locomotive input file contains geometry for approximately the first 12 ft of the locomotive. 

Because this input file is for a half-symmetric model, a mass corresponding to 130,000 pounds of 

weight is attached to the model. Two views of the locomotive are shown in Figure A11.
149

Figure A11. Side and Front Views of Rigid Locomotive Model
150

****************************** BEGIN INPUT FILE******************************

*Heading

** USDOT/VOLPE CENTER FINITE ELEMENT MODEL

** FULLY RIGID LOCOMOTIVE DESIGNED FOR 1-D MODELING

** LOCOMOTIVE BASED ON F-40 TYPE

** HALF-SYMMETRY INPUT FILE 

** WHOLE LOCOMOTIVE WEIGHT: 260,000 POUNDS

** UNITS: INCHES/POUNDS/SECONDS

** JULY, 2010

** Generated by: Abaqus/CAE 6.10-1

**

** PARTS

**

*Part, name=PART-1

*Node

 1, 167.942993, 59.8800011, 98.0625

 2, 161.143005, 59.8800011, 98.0625

 3, 167.942993, 59.8800011, 66.0625

 4, 78.322998, 59.8800011, 66.0625

 5, 167.942993, 0., 179.5625

 6, 81.322998, 0., 179.5625

 7, 54.3730011, 0., 166.862503

 8, 167.942993, 33.6899986, 179.5625

 9, 81.322998, 59.8800011, 133.942505

 10, 78.322998, 59.8800011, 133.942505

 11, 78.322998, 59.8800011, 163.502502

 12, 81.322998, 59.8800011, 161.502502

 13, 78.322998, 59.8800011, 130.942505

 14, 78.322998, 59.8800011, 116.002502

 15, 161.143005, 59.8800011, 133.942505

 16, 161.143005, 59.8800011, 161.502502

 17, 161.143005, 59.8800011, 101.0625

 18, 161.143005, 59.8800011, 130.942505

 19, 161.143005, 59.8800011, 163.502502

 20, 167.942993, 59.8800011, 163.502502

 21, 167.942993, 59.8800011, 167.0625

 22, 167.942993, 37.8079987, 178.462494

 23, 81.322998, 33.6899986, 179.5625

 24, 81.322998, 37.8079987, 178.472504

 25, 57.5040016, 9., 166.862503

 26, 58.125, 10.7849998, 166.862503

 27, 66.6159973, 35.0439987, 166.862503

 28, 58.132, 10.783, 177.5625

 29, 57.4830017, 8.99190044, 177.5625

 30, 58.132, 10.783, 179.5625

 31, 57.4830017, 8.99190044, 179.5625

 32, 75.310997, 59.862999, 167.052505

 33, 62.2120018, 59.8800011, 119.8125

 34, 63.9179993, 56.5620003, 130.160507

 35, 64.3919983, 56.5470009, 131.889496

 36, 72.861969, 56.5663757, 162.376297

 37, 66.6299973, 35.0439987, 177.5625

 38, 48.9730415, 2.24654722, 144.558914

 39, 53.9304123, 2.53624678, 162.100143

 40, 81.322998, 61.6300011, 133.942505

 41, 161.143005, 61.6300011, 133.942505

 42, 81.322998, 61.6300011, 130.942505

 43, 161.143005, 61.6300011, 130.942505

 44, 167.942993, 61.6300011, 101.0625

 45, 167.942993, 61.6300011, 161.502502

 46, 161.143005, 61.6300011, 101.0625

 47, 161.143005, 61.6300011, 161.502502

 48, 20.6900311, 0., 136.253281

 49, 18.1748695, 59.2774734, 60.0625

 50, 22.07197, 59.2542038, 66.0625

 51, 27.934, 41., 9.0625

 52, 18.3192978, 0., 36.7498283

 53, 15.5744066, 0., 36.7498283

 54, 1.76894331, 5.32121038, 28.9578266

 55, 3.57440639, 6.60263443, 28.9578266
151

 56, 2.67061162, 5.68379116, 28.9578266

 57, 0.401960254, 3.98941922, 28.9578266

 58, 0.977025032, 4.76697016, 28.9578266

 59, 0.099995479, 3.06867123, 28.9578266

 60, 0.099995479, 1.14263237, 30.0413265

 61, 0.099995479, 0., 28.9578266

 62, 3.51490474, 0.654233992, 28.9578266

 63, 3.98739839, 0., 28.9578266

 64, 0.099995479, 0., 30.0413265

 65, 3.31792188, 0., 30.0413265

 66, 3.40018868, 1.60872662, 28.9578266

 67, 2.67061162, 5.68379116, 40.0418282

 68, 0.099995479, 1.14263237, 38.9583282

 69, 0.099995479, 0., 40.0418282

 70, 0.977025032, 4.76697016, 40.0418282

 71, 1.76894331, 5.32121038, 40.0418282

 72, 0.099995479, 0., 38.9583282

 73, 3.98739839, 0., 40.0418282

 74, 3.31792188, 0., 38.9583282

 75, 0.099995479, 3.06867123, 40.0418282

 76, 0.401960254, 3.98941922, 40.0418282

 77, 3.51490474, 0.654233992, 40.0418282

 78, 5.75145721, 5.7997303, 40.0418282

 79, 15.5720844, 3.87475181, 31.1248264

 80, 18.5401859, 3.81961679, 31.1248264

 81, 15.5744066, 0., 31.1248264

 82, 3.40018868, 1.60872662, 40.0418282

 83, 3.57440639, 6.60263443, 40.0418282

 84, 30.2979393, 56.9446068, 128.484482

 85, 58.9190598, 59.8919106, 66.0608368

 86, 161.143005, 61.6300011, 116.002502

 87, 58.7904701, 30.4786301, 144.5345

 88, 59.8902054, 34.9131279, 142.917557

 89, 161.143005, 59.8800011, 116.002502

 90, 57.4934998, 8.99594975, 172.212494

 91, 58.1285019, 10.7840004, 172.212494

 92, 15.5744066, 0., 32.2498283

 93, 18.3192978, 0., 31.1248264

 94, 18.3192978, 0., 32.2498283

 95, 15.5744066, 1.95114112, 31.1248264

 96, 58.2618256, 31., 142.816605

 97, 59.3854752, 34.7812653, 141.263779

 98, 67.881691, 38.7345238, 178.0345

 99, 66.3495865, 34.3354263, 179.5625

 100, 161.143005, 59.8800011, 167.0625

 101, 66.1316681, 59.8799019, 133.987289

 102, 74.003212, 59.8690262, 162.327911

 103, 68.1072845, 39.3478088, 166.862503

 104, 161.018005, 59.8800011, 66.0625

 105, 14.4651852, 0., 31.1248264

 106, 8.65684605, 0.948336065, 41.1248283

 107, 8.69752693, 0., 41.1248283

 108, 8.71603775, 2.63976431, 40.0414925

 109, 9.53989887, 2.18784833, 40.0414925

 110, 14.1617727, 1.99973011, 31.1248264

 111, 5.75145721, 5.7997303, 37.8748283

 112, 3.39199758, 9.62334061, 37.8748283

 113, 14.4651852, 0., 37.8748283

 114, 10.4428129, 1.99973011, 37.8748283

 115, 8.71603775, 2.63976431, 31.1248264

 116, 9.53989887, 2.18784833, 37.8748283

 117, 3.34182882, 8.61192608, 37.8748283

 118, 15.5744066, 0., 37.8748283

 119, 15.5720844, 3.87475181, 37.8748283

 120, 13.7156467, 4.44362879, 31.1248264

 121, 3.55879021, 10.6221542, 31.1248264

 122, 9.53989887, 2.18784833, 31.1248264

 123, 8.71603775, 2.63976431, 37.8748283

 124, 11.6615076, 6.49122286, 37.8748283

 125, 9.37123108, 10.8283968, 37.8748283

 126, 14.1617727, 1.99973011, 37.8748283
152

 127, 3.4053607, 7.60121346, 37.8748283

 128, 15.5744066, 2.12472296, 37.8748283

 129, 18.3192978, 0., 37.8748283

 130, 13.9651852, 0., 27.8748264

 131, 4.45807409, 2.11810708, 27.8748264

 132, 14.4744062, 0., 27.8748264

 133, 8.71603775, 2.63976431, 27.8748264

 134, 13.7156467, 4.44362879, 37.8748283

 135, 3.55879021, 10.6221542, 37.8748283

 136, 18.5401859, 3.81961679, 37.8748283

 137, 3.57440639, 6.60263443, 37.8748283

 138, 14.6130104, 4.054636, 37.8748283

 139, 10.4428129, 1.99973011, 31.1248264

 140, 8.73545933, 11.5156822, 37.8748283

 141, 3.83903623, 11.5952816, 37.8748283

 142, 3.70096731, 2.42872977, 40.0414925

 143, 14.1742048, 1.95114088, 41.1248283

 144, 10.4428129, 1.99973011, 41.1248283

 145, 9.53989887, 2.18784833, 41.1248283

 146, 13.9651852, 0., 41.1248283

 147, 14.4744062, 0., 41.1248283

 148, 8.71603775, 2.63976431, 41.1248283

 149, 8.18554401, 1.77063227, 41.1248283

 150, 10.4428129, 1.99973011, 40.0414925

 151, 6.90897226, 3.09021854, 41.1248283

 152, 6.90897226, 3.09021854, 40.0414925

 153, 7.3380537, 2.19558096, 41.1248283

 154, 3.70096731, 2.42872977, 41.1248283

 155, 4.45807409, 2.11810708, 41.1248283

 156, 11.6615076, 6.49122286, 31.1248264

 157, 9.37123108, 10.8283968, 31.1248264

 158, 3.57440639, 6.60263443, 31.1248264

 159, 14.6130104, 4.054636, 31.1248264

 160, 8.73545933, 11.5156822, 31.1248264

 161, 3.83903623, 11.5952816, 31.1248264

 162, 3.34182882, 8.61192608, 31.1248264

 163, 3.39199758, 9.62334061, 31.1248264

 164, 3.4053607, 7.60121346, 31.1248264

 165, 3.70096731, 2.42872977, 27.8748264

 166, 8.65684605, 0.948336065, 27.8748264

 167, 8.18554401, 1.77063227, 27.8748264

 168, 7.83922768, 2.97724795, 31.1248264

 169, 3.70096731, 2.42872977, 31.1248264

 170, 8.69752693, 0., 27.8748264

 171, 7.83922768, 2.97724795, 27.8748264

 172, 10.4428129, 1.99973011, 27.8748264

 173, 3.70096731, 2.42872977, 28.9581604

 174, 7.3380537, 2.19558096, 27.8748264

 175, 14.1742048, 1.95114088, 27.8748264

 176, 9.53989887, 2.18784833, 27.8748264

 177, 47.7130013, 0., 142.862503

 178, 57.5089989, 0., 177.5625

 179, 57.5089989, 0., 179.5625

 180, 45.2702484, 31., 142.381302

 181, 44.7895966, 35.7113838, 140.807663

 182, 44.3954277, 0., 142.862503

 183, 45.0859528, 56.9468269, 129.232864

 184, 27.934, 26.02841, 48.1875

 185, 26.3169994, 31., 134.151077

 186, 25.4385452, 31., 132.291351

 187, 29.5859261, 59.3337784, 119.820122

 188, 27.944397, 59.3558388, 66.062233

 189, 11.9149094, 10.3664589, 66.0625

 190, 9.76114368, 0., 66.0625

 191, 19.1986504, 0., 133.730804

 192, 11.0030947, 25.8867302, 60.0625

 193, 27.934, 0., 48.1875

 194, 27.934, 26.125, 60.0625

 195, 11.067338, 26.125, 66.0625

 196, 5.72649717, 0., 60.0625

 197, 27.934, 31., 48.1875
153

 198, 5.70541191, 0., 63.0624962

 199, 12.03866, 31.1362305, 60.0625

 200, 18.114048, 59.2658386, 63.0621109

 201, 27.9339981, 59.461689, 60.0613098

 202, 27.934, 0., 60.0560417

 203, 7.81957102, 10.375, 63.0632477

 204, 7.81957102, 10.3664589, 66.0625

 205, 27.934, 10.375, 52.159462

 206, 27.934, 0., 52.1595879

 207, 27.934, 10.4399996, 9.0625

 208, 27.934, 31.0390625, 9.0625

 209, 27.934, 46.629631, 24.1736107

 210, 27.934, 55.4259262, 47.7847214

 211, 27.934, 59.2962952, 58.1736107

 212, 27.934, 10.4399996, 26.1248264

 213, 27.934, 30.9188347, 25.1098576

 214, 7.91185236, 10.375, 60.0625

 215, 27.934, 10.375, 60.0625

 216, 15.1792574, 26.0783482, 66.0625

 217, 5.68432665, 0., 66.0625

 218, 18.0532093, 59.2542038, 66.0625

 219, 27.2928429, 10.375, 60.0625

 220, 27.934, 0., 66.0625

 221, 27.934, 10.375, 66.0625

 222, 13.7154636, 10.3812084, 65.0625

 223, 27.2928543, 10.375, 62.0625

 224, 25.2556648, 10.375, 65.0625

 225, 27.934, 31.125, 66.0625

 226, 27.934, 31.125, 60.0625

 227, 12.1000671, 31.1362305, 66.0625

 228, 16.2295151, 31.1334229, 66.0625

 229, 27.934, 25.875, 52.0625

 230, 11.0631142, 25.8867302, 63.0293884

 231, 27.934, 31.0490627, 52.0634613

 232, 12.1452255, 31.1362305, 63.0293884

 233, 20.5744057, 0., 42.1875

 234, 17.5744057, 0., 42.1875

 235, 17.5744057, 0., 39.1875

 236, 20.5744057, 10.4399996, 30.3899994

 237, 20.5744057, 10.4399996, 39.1875

 238, 20.5744057, 10.4399996, 42.1875

 239, 17.5744057, 10.4399996, 39.1875

 240, 17.5744057, 10.4399996, 42.1875

 241, 27.934, 10.4399996, 42.2693863

 242, 27.934, 10.4399996, 48.1875

 243, 27.184, 9.43999958, 26.1248264

 244, 27.184, 0., 26.1248264

 245, 27.184, 9.43999958, 30.8648262

 246, 27.184, 0., 30.8648262

 247, 18.5744057, 10.4399996, 28.1248264

 248, 18.5744057, 10.4399996, 26.1248264

 249, 18.5744057, 9.43999958, 26.1248264

 250, 18.5744057, 0., 26.1248264

 251, 18.5744057, 9.43999958, 30.8648262

 252, 18.5744057, 0., 30.8648262

8888888, 150.0, 0., 34.5

 253, 22.2162247, 59.3531151, 60.0625

 254, 167.942993, 61.6300011, 116.002502

 255, 167.942993, 61.6300011, 130.942505

 256, 167.942993, 61.6300011, 133.942505

 257, 161.143005, 37.8079987, 178.462494

 258, 161.143005, 33.6899986, 179.5625

 259, 161.143005, 0., 179.5625

 260, 56.3731041, 9.4654789, 162.199432

 261, 57.0013237, 11.2475662, 162.22496

 262, 67.0327148, 39.7239189, 162.592499

 263, 65.5448227, 35.4830818, 162.57222

 264, 23.8785725, 23.25, 132.651215

 265, 20.7586231, 7.75, 133.370941

*Element, type=R3D4

1, 87, 96, 97, 88
154

2, 91, 26, 25, 90

3, 28, 91, 90, 29

4, 30, 28, 29, 31

6, 13, 42, 40, 10

7, 47, 45, 20, 19

8, 44, 46, 2, 1

11, 201, 188, 225, 226

12, 202, 215, 221, 220

13, 233, 238, 242, 193

14, 197, 213, 209, 210

15, 212, 207, 208, 213

16, 213, 208, 51, 209

17, 234, 240, 238, 233

18, 239, 240, 234, 235

19, 239, 237, 238, 240

20, 226, 225, 227, 232

21, 197, 231, 229, 184

22, 231, 226, 194, 229

23, 215, 194, 229, 205

24, 202, 215, 205, 206

25, 206, 205, 242, 193

26, 205, 229, 184, 242

27, 203, 204, 217, 198

28, 203, 214, 196, 198

29, 204, 203, 230, 195

30, 195, 230, 232, 227

31, 230, 203, 214, 192

32, 232, 230, 192, 199

33, 232, 227, 218, 200

34, 199, 232, 200, 49

35, 218, 227, 228, 50

36, 228, 227, 195, 216

37, 195, 204, 189, 216

38, 204, 217, 190, 189

39, 220, 190, 189, 221

40, 228, 225, 221, 189

41, 6, 31, 99, 23

43, 31, 29, 178, 179

44, 23, 99, 98, 24

47, 98, 103, 27, 37

48, 30, 28, 37, 99

50, 16, 47, 41, 15

51, 21, 20, 19, 100

52, 100, 19, 11, 32

53, 34, 35, 88, 97

54, 35, 101, 102, 36

55, 11, 12, 16, 19

57, 10, 9, 12, 11

58, 101, 10, 11, 102

59, 41, 43, 42, 40

60, 15, 41, 40, 9

61, 33, 14, 13, 101

64, 13, 14, 89, 18

65, 89, 86, 43, 18

66, 89, 17, 46, 86

67, 89, 104, 4, 14

68, 104, 3, 1, 2

69, 4, 14, 33, 85

71, 185, 186, 191, 48

73, 187, 186, 228, 50

74, 225, 228, 50, 188

75, 34, 183, 181, 97

76, 97, 181, 180, 96

77, 84, 183, 181, 185

79, 96, 180, 182, 177

80, 48, 185, 180, 182

81, 251, 245, 243, 249

82, 249, 243, 244, 250

83, 252, 250, 249, 251

84, 246, 245, 251, 252

85, 46, 44, 254, 86
155

86, 86, 254, 255, 43

87, 43, 255, 256, 41

88, 41, 256, 45, 47

89, 100, 21, 22, 257

90, 257, 22, 8, 258

91, 258, 8, 5, 259

92, 23, 258, 259, 6

93, 24, 257, 258, 23

94, 32, 100, 257, 24

95, 33, 101, 35, 34

96, 42, 13, 18, 43

97, 85, 33, 187, 188

99, 96, 177, 38, 87

100, 7, 39, 38, 177

101, 26, 261, 260, 25

102, 7, 25, 260, 39

103, 261, 263, 27, 26

104, 27, 263, 262, 103

105, 262, 36, 32, 103

107, 204, 203, 215, 221

109, 50, 188, 201, 253

110, 50, 253, 200, 218

112, 75, 76, 57, 59

113, 76, 70, 58, 57

114, 70, 71, 54, 58

115, 71, 67, 56, 54

116, 141, 140, 160, 161

117, 137, 127, 164, 158

118, 127, 117, 162, 164

119, 117, 112, 163, 162

120, 112, 135, 121, 163

121, 135, 141, 161, 121

122, 81, 132, 130, 105

123, 136, 80, 79, 119

124, 119, 118, 129, 136

125, 81, 93, 80, 79

126, 146, 147, 118, 113

127, 140, 125, 157, 160

128, 125, 124, 156, 157

129, 124, 134, 120, 156

130, 107, 106, 166, 170

131, 106, 149, 167, 166

132, 149, 153, 174, 167

133, 153, 155, 131, 174

134, 142, 82, 66, 173

135, 66, 62, 77, 82

136, 77, 73, 63, 62

137, 125, 140, 141, 135

138, 60, 68, 74, 65

141, 153, 155, 154, 151

142, 154, 142, 152, 151

143, 151, 153, 149, 148

144, 149, 106, 145, 148

145, 148, 151, 152, 108

146, 108, 109, 145, 148

147, 145, 109, 150, 144

148, 118, 128, 143, 147

149, 82, 142, 76, 75

151, 152, 142, 67, 83

152, 108, 78, 83, 152

153, 128, 119, 138, 126

154, 116, 114, 150, 109

155, 109, 116, 123, 108

156, 108, 123, 111, 78

157, 78, 111, 137, 83

158, 126, 138, 134, 114

159, 123, 124, 134, 116

160, 123, 111, 125, 124

163, 117, 127, 137, 125

164, 125, 135, 112, 117

165, 174, 171, 165, 131
156

166, 133, 167, 174, 171

167, 176, 166, 167, 133

168, 81, 95, 175, 132

169, 61, 64, 65, 63

170, 72, 69, 73, 74

171, 63, 73, 74, 65

172, 75, 69, 73, 77

174, 62, 59, 61, 63

176, 59, 57, 173, 66

180, 160, 157, 121, 161

181, 157, 162, 163, 121

182, 157, 158, 164, 162

183, 79, 159, 110, 95

184, 159, 120, 139, 110

186, 175, 110, 139, 172

187, 139, 122, 176, 172

188, 176, 122, 115, 133

189, 133, 115, 168, 171

190, 171, 168, 169, 173

192, 156, 122, 139, 120

195, 158, 55, 173, 169

197, 145, 107, 146, 144

198, 143, 144, 146, 147

199, 142, 71, 70, 76

200, 120, 134, 138, 159

201, 159, 138, 119, 79

202, 172, 170, 166, 176

203, 175, 130, 170, 172

205, 67, 137, 158, 56

210, 158, 168, 156, 157

211, 93, 94, 92, 81

212, 53, 118, 129, 52

215, 170, 107, 113, 105

216, 105, 92, 53, 113

221, 155, 142, 173, 131

222, 61, 64, 60, 59

223, 72, 69, 75, 68

224, 68, 60, 59, 75

226, 143, 126, 150, 144

228, 231, 211, 210, 197

229, 226, 231, 211, 201

230, 221, 215, 194, 225

233, 231, 229, 230, 232

235, 183, 187, 33, 34

236, 212, 248, 247, 236

237, 241, 212, 236, 237

240, 197, 184, 212, 213

242, 190, 189, 265, 191

243, 189, 216, 264, 265

244, 216, 228, 186, 264

*Element, type=R3D3

5, 16, 47, 19

9, 2, 17, 46

10, 10, 40, 9

42, 31, 179, 6

45, 24, 32, 98

46, 98, 103, 32

49, 99, 98, 37

56, 11, 32, 102

62, 13, 10, 101

63, 242, 238, 241

70, 84, 185, 186

72, 187, 84, 186

78, 181, 180, 185

98, 50, 188, 187

106, 32, 102, 36

108, 215, 203, 214

111, 200, 253, 49

139, 65, 64, 60

140, 68, 72, 74

150, 142, 71, 67
157

161, 114, 116, 134

162, 111, 137, 125

173, 75, 77, 82

175, 66, 59, 62

177, 173, 58, 57

178, 173, 54, 58

179, 173, 56, 54

185, 175, 110, 95

191, 165, 173, 171

193, 173, 56, 55

194, 115, 122, 156

196, 106, 107, 145

204, 175, 132, 130

206, 56, 158, 55

207, 137, 67, 83

208, 169, 168, 158

209, 168, 115, 156

213, 81, 92, 105

214, 53, 118, 113

217, 130, 105, 170

218, 113, 146, 107

219, 131, 165, 173

220, 142, 155, 154

225, 126, 114, 150

227, 128, 126, 143

231, 225, 194, 226

232, 231, 226, 232

234, 84, 187, 183

238, 241, 237, 238

239, 184, 242, 241

241, 184, 241, 212

*Nset, nset=PART-1-RefPt_, internal

8888888,

*Elset, elset=PART-1, generate

 1, 244, 1

*End Part

** 

**

** ASSEMBLY

**

*Assembly, name=Assembly

** 

*Instance, name=PART-1-1, part=PART-1

*End Instance

** 

*Nset, nset=_Ref-Pt_PART-1-1_8888888, internal, instance=PART-1-1

8888888,

*Nset, nset=LOCO_MASS, instance=PART-1-1

8888888,

*Nset, nset=LOCO-NODES, instance=PART-1-1, generate

 1, 265, 1

*Elset, elset=LOCO-ELEMENTS, instance=PART-1-1, generate

 1, 244, 1

*Rigid Body, ref node=PART-1-1.PART-1-RefPt_, elset=PART-1-1.PART-1

*Element, type=MASS, elset=LOCO_MASS_LOCO_MASS_X_

1, PART-1-1.8888888

*Mass, elset=LOCO_MASS_LOCO_MASS_X_

336.439, 

*End Assembly

******************************** END INPUT FILE******************************
158

Appendix D. Railroad Safety Advisory Committee Passenger Safety 

Working Group Engineering Task Force

At the time of acceptance of this report by the Railroad Safety Advisory Committee, the 

Engineering Task Force included the following members:

Robert Adduci US DOT/Volpe Center

Dan Alpert Federal Railroad Administration

Kiichiro Arie Central Japan Railway Company 

Allen Bieber STV, Inc.

Charlie Bielitz Federal Railroad Administration

Stephen Bonina Interfleet Technology 

Michael Burshtin National Railroad Passenger Corporation (AMTRAK)

Gordon Campbell Interfleet, Inc.

Michael Carolan US DOT/Volpe Center

Anya Carroll US DOT/Volpe Center

David Carter New Jersey TRANSIT

Michael Coltman US DOT/Volpe Center

Richard F. Conway MTA Metro-North

Joshua D. Coran Talgo, Inc.

Mike Denn Long Island Railroad

Dominic DiBrito LTK Engineering Services

Bob Dorer US DOT/Volpe Center

Raymond Dumoulin Bombardier Transportation

Don Eccleston Long Island Rail Road LIRR

Dale Engelhardt National Railroad Passenger Corporation (AMTRAK)
159

Gary Fairbanks Federal Railroad Administration

Nora Friend Talgo, Inc.

Robert Fries Transportation Technology Center, Inc.

Wayne Friesner Dallas Area Rapid Transit 

Edward Gacsi New Jersey Transit

Gregory A. Gagarin National Railroad Passenger Corporation (AMTRAK)

Robert Galbraith Mitsubishi Electric Power Products, Inc. 

Emmanuel Garcia MTA Metro-North

Brian Gilleran Federal Railroad Administration

Tim Good Stadler Rail

Glenn Gough Siemens Transportation Systems, Inc.

James Grady Association of American Railroads Safety and Operations 

Department 

Raymond Green Denton County Transportation Authority

Hugues Gregoire Bombardier Transportation 

Cynthia Gross Federal Railroad Administration

Dennis Harwig Edison Welding Institute

Toshiyuki Hasegawa KPS N.A., Inc.

Tom Hunt Nippon Sharyo USA, Inc.

Stanton Hunter California Department of Transportation Division of Rail

Tak Ishigami Kawasaki Rail Car, Inc.

Kari Jacobsen US DOT/Volpe Center

Paul Jamieson Wabtec Transit - Brakes and Couplers

Tony Jones Voith Turbo
160

Larry Kelterborn Interfleet Technology, Inc.

Kevin Kesler Federal Railroad Administration

Toshinori Kimura Kawasaki Heavy Industries, LTD

Fujio Kitamura Japanese Ministry of Land, Infrastructure, Transport and Tourism

Dan Knote Federal Railroad Administration

Richard Krisak Metropolitan Atlanta Rapid Transit Authority

Peter Lapre Federal Railroad Administration, Region 1

Paul Larouche Bombardier Transportation

Robert Lauby Federal Railroad Administration

Dan Lauzon Brotherhood of Locomotive Engineers and Trainmen

Thomas LeBeau Denton County Transportation Authority

Dominique LeCorre Alstom Transport

Luca Lenzi Ansaldobreda

Jack Lockerby Raul Bravo & Associates

George Long Siemens Transportation Systems, Inc.

William Lydon, Jr. Southern California Regional Rail Authority (SCRRA)

Frank Maldari Long Island Railroad

Kenneth R. Mannen Kawasaki Rail Car, Inc.

John Mardente Federal Railroad Administration

Eloy Martinez Federal Railroad Administration

Michael Masci Federal Railroad Administration

Ron Mayville Simpson Gumpertz & Heger

Patrick McLaughlin Federal Railroad Administration
161

Dave Mears American Short Line Railroad Association

James Michel HNTB Corporation

Jeffrey F. Moller Association of American Railroads (AAR)

Brenda Moscoso Federal Railroad Administration

Michelle Muhlanger US DOT/Volpe Center

Brian Murphy Bombardier Transportation

Ron Newman Federal Railroad Administration

Barbara Pelletier Federal Railroad Administration

Benjamin Perlman US DOT/Volpe Center

Anand Prabhakaran Sharma & Associates, Inc.

Mario Raymond Bombardier Transportation 

Lorenzo Reffreger Ansaldobreda

Robert Scarola Federal Railroad Administration

Gerhard Schmidt Siemens Transportation Systems, Inc.

Martin Schroeder American Public Transportation Association (APTA)

Kristine Severson US DOT/Volpe Center

Vinny Sharma Sharma & Associates

Takashi Shizuka Nippon Sharyo

Melissa Shurland Federal Railroad Administration

John Sneed Federal Railroad Administration

Dave (D.E.) Staplin National Railroad Passenger Corporation (AMTRAK)

Alois Starlinger Stadler Rail

Rich Stegner Motive Power
162

Jo Strang Federal Railroad Administration

Phil Strong PS Consulting

Laura Sullivan US DOT/Volpe Center

Mike Trosino National Railroad Passenger Corporation (AMTRAK)

Stewart Trout Massachusetts Bay Commuter Rail Company (MBCR)

Thomas Tulley Federal Railroad Administration

John Tunna Transportation Technology Center, Inc.

David Tyrell US DOT/Volpe Center

Rich Vadnal Nippon Sharyo

William Verdeyen Brotherhood of Locomotive Engineers and Trainmen

Teresa Vicente Talgo, Inc.

Dave Ward Alstom Transport

Michael P. Wetherell Denton County Transportation Authority

Charlie Whalen Federal Railroad Administration

Brian Whitten Ensco, Inc.

Gary Widell Nippon Sharyo

Cliff Woodbury LTK Engineering Services

Eric Wrobley LTK Engineering Services

Theresa Zemelman Raul Bravo & Associates
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Definitions

Existing Terms in 49 CFR 238

For consistency with Part 238, terms that are used in this report that are already defined in Part 

238 have the same meaning. Terms that are defined in § 238.5 (Definitions) and also used within 

this report are listed in Appendix B. Selected CFR References.

New Terms

Definitions are being added for terms that are not specifically defined in Part 238. The new 

definitions are provided as follows:

Vertical offset means the additional difference in height above top of rail between the main 

structures of two pieces of rail equipment from their normal difference, if any, in height.

Longitudinal load carrying component means an identifiable structural element of the car body 

that is capable of carrying axial and bending loads, such as side sills, and carries a significant 

portion of the applied longitudinal load when the load is applied in-line with the collision load 

path of the car body. Structural elements capable of carrying only in-plane loads, such as the 

outer skin, that do not carry a significant portion of the applied load are not considered 

longitudinal load carrying components.

Crippling load means the largest compressive load an occupied volume can sustain before its 

structure is overwhelmed. It is indicated by the peak on a load-displacement characteristic.
164

Abbreviations and Acronyms

AAR Association of American Railroads

APTA American Public Transportation Association

AT antitelescoping

ATD anthropomorphic test dummy

CEM crash energy management

CFR Code of Federal Regulations

CG center of gravity

DMU diesel multiple-unit locomotive

EMU electric multiple-unit locomotive

EN EuroNorm

ETF Engineering Task Force

FE finite element

FRA Federal Railroad Administration

FTA Federal Transit Administration

g gravitational acceleration (32.2 feet/second/second)

in inch(es)

ips inch(es) per second

kip kilopound(s)

mph mile(s) per hour

ms millisecond(s)

MU multiple unit

NTSB National Transportation Safety Board

OVI occupied volume integrity

PBC pushback coupler

PEAM primary energy absorption mechanism

psi per square inch

RMS Railway Mail Service

RPO Railway Post Office

RSAC Railroad Safety Advisory Committee

RSSB Rail Safety and Standards Board

SIV secondary impact velocity

SOA state-of-the-art