U.S. Department of 

Transportation 

Federal Railroad 

Administration

Track Inspection Time Study* 

* Required by Section 403 of the Rail Safety Improvement Act of 2008 (Public Law 110-

432, Div. A.) 
NOTICE 

This document is disseminated under the sponsorship of the 

Department of Transportation in the interest of information 

exchange. The United States Government assumes no liability for 

its contents or use thereof. 

NOTICE 

The United States Government does not endorse products or 

manufacturers. Trade or manufacturers’ names appear herein 

solely because they are considered essential to the objective of this 

report. 
iii

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 34 5

Inches

Centimeters 01 3 2 6 11 4 5 7 13 8 9 10 12

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 
iv

Table of Contents 

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

1. Introduction ................................................................................................................................ 5

2. Track Inspection Background and Methodology ....................................................................... 8

2.1 Defective Track Conditions Addressed in the Track Safety Standards ............................... 8

2.2 Prescriptive vs. Performance-Based Thresholds .................................................................. 8

2.3 Probability of Detection Theory ........................................................................................... 9

2.4 Remedial Actions ............................................................................................................... 10

2.5 Frequency of Inspection ..................................................................................................... 11

3. Current Track Inspection Practices and Procedures ................................................................. 12

3.1 Visual Inspections .............................................................................................................. 12

3.2 Automated Inspection Systems .......................................................................................... 13

3.3 Monitoring Systems ........................................................................................................... 15

3.4 Track Safety Standards Inspection Requirements .............................................................. 16

3.4.1 Visual Inspections Required by the Track Safety Standards ....................................... 16

3.4.2 Automated Inspections Required by the Track Safety Standards ................................ 18

3.4.3 Summary of Inspections Required by the Track Safety Standards .............................. 20

3.5 FRA’s Role ......................................................................................................................... 21

4. Results of Study ........................................................................................................................ 22

4.1 Track Inspector Survey Results .......................................................................................... 22

4.1.1 Sample Size Methodology and Response Rate ............................................................ 22

4.1.2 Potential Survey Biases ................................................................................................ 23

4.1.3 Experience .................................................................................................................... 23

4.1.4 Initial and Subsequent Training ................................................................................... 25

4.1.5 Supervisory Oversight .................................................................................................. 25

4.1.6 Length of Workday and Overtime Burden ................................................................... 26

4.1.7 Time Allocation ............................................................................................................ 28

4.1.8 Total Territory Size ...................................................................................................... 29

4.1.9 Track Miles Covered Per Day ...................................................................................... 30

4.1.10Inspection Speed ........................................................................................................... 30

4.1.11Detection of Track Defects ........................................................................................... 32

4.1.12Calculated Inspection Speed ........................................................................................ 32

4.1.13Calculated Inspection Frequency ................................................................................. 33

4.1.14Relevant Correlations ................................................................................................... 34

4.1.15Summary of Track Inspectors’ Comments ................................................................... 35

4.2 Salient Points from Labor Union and Railroad Management Interviews .......................... 36

4.3 Outputs from Ideal Observer Model .................................................................................. 38

4.4 Defects Found by FRA Track Inspectors ........................................................................... 39

5. Recommendations .................................................................................................................... 42

5.1 Integration of Visual and Expanded Automated Inspections ............................................. 42

5.2 Track Inspector Training .................................................................................................... 43

5.3 Speed of Inspection ............................................................................................................ 43
v

5.4 Railroad Operating Practices and Culture .......................................................................... 44

Appendix A. Section 403 of the Rail Safety Improvement Act of 2008 (Public Law 110-432, 

Div. A.) ......................................................................................................................................... 46

Appendix B. Track Inspector Survey ............................................................................................ 47

Appendix C. Detection of Track Defects Through Visual Inspection, ......................................... 55

Appendix D. Results of Interviews with Labor Union Officials .................................................. 57

Appendix E. Results of Interviews with Roadmasters/Track Supervisors ................................... 62

Appendix F. Results of Interviews with Division Engineers ........................................................ 72

Appendix G. Results of Interviews with System Level Officers .................................................. 77

Appendix H. Ideal Observer for Visual Track Inspection ............................................................ 81

H.1 Theory of the Ideal Observer .............................................................................................. 81

H.2 Human Factors Considerations .......................................................................................... 82

H.2.1 Visual Acuity ................................................................................................................ 82

H.2.2 Visual Search ................................................................................................................ 84

H.2.3 Attention ....................................................................................................................... 86

H.3 ADDENDUM: Visual Angle (θ) and Probability of Correct Detection ............................ 89

Appendix I. RSAC Recommended Definition of “Qualified Operator” in 49 CFR § 213.238 ... 91

References ..................................................................................................................................... 93
vi

Illustrations 

Figure 1. Examples of ROC curves ............................................................................................. 10

Figure 2. Number of years as a track inspector ........................................................................... 24

Figure 3. Number of years on current territory ............................................................................ 24

Figure 4. Subsequent track inspection training ............................................................................ 25

Figure 5. Frequency of supervisory oversight ............................................................................. 26

Figure 6. Number of days in the past month worked more than scheduled length of workday . 27

Figure 7. Number of rest days worked in the past month ............................................................ 27

Figure 8. Time spent performing inspection and repair duties .................................................... 28

Figure 9. Time spent performing other activities (besides inspection and repair) ....................... 29

Figure 10. Number of mainline track miles in territory ............................................................... 29

Figure 11. Number of track miles inspected on a typical day ..................................................... 30

Figure 12. Reported hi-rail inspection speeds .............................................................................. 31

Figure 13. Conditions that cause adjustments to typical inspection speeds ................................ 32

Figure 14. Calculated inspection speeds ...................................................................................... 33

Figure 15. Calculated inspection frequency for track classes 1–3 and excepted track ................ 34

Figure 16. Calculated inspection frequency for track classes 4 and 5 ......................................... 34

Figure 17. Correlation of number of mainline track miles and inspection speed ........................ 35

Figure 18. Ideal observer output for a 16 object search with 95-percent detection accuracy ...... 38

Figure 19. Track defects identified by FRA track inspectors (2006–2009) ................................ 39

Figure 20. Historical trend of most common defects identified by FRA track inspectors .......... 40

Figure 21. Diagram of observer, object, and relevant parameters ............................................... 82

Figure 22. Relationship between maximum inspection speed, defect size and detection accuracy

............................................................................................................................................... 83

Figure 23. Relationship between maximum inspection speed, defect size, and number of search 

objects for 90-percent detection accuracy ............................................................................ 84

Figure 24. Relationship between maximum inspection speed, defect size, and number of search 

objects for 95-percent detection accuracy ............................................................................. 85

Figure 25. Relationship between maximum inspection speed, defect size, and number of search 

objects for 99-percent detection accuracy ............................................................................. 85

Figure 26. Relationship between visual inspection speed, defect size, and number of search 

objects for vigilance-adjusted, 90-percent correct detection accuracy ................................. 87

Figure 27. Relationship between visual inspection speed, defect size, and number of search 

objects for vigilance-adjusted, 95-percent correct detection accuracy ................................. 87

Figure 28. Relationship between visual inspection speed, defect size, and number of search 

objects for vigilance-adjusted, 99-percent correct detection accuracy ................................. 88
vii

Tables 

Table 1. Subparts of Track Safety Standards ................................................................................. 6

Table 2. FRA track inspection requirements for each class of track ........................................... 21

Table 3. Primary method of visual inspection ............................................................................. 30
viii

Acronyms 

ATIP Automated Track Inspection Program 

BMWED Brotherhood of Maintenance of Way Employes Division 

C3RS Confidential Close Call Reporting System 

CFR Code of Federal Regulations 

CWR Continuous Welded Rail 

DOT U.S. Department of Transportation 

FRA Federal Railroad Administration 

GPR Ground Penetrating Radar 

GRMS Gage Restraint Measurement System 

LIDAR Light Detection and Ranging 

MPH Miles Per Hour 

NIP National Inspection Plan 

NTSB National Transportation Safety Board 

NPRM Notice of Proposed Rulemaking 

PDF Probability Density Function 

POD Probability of Detection 

RITF Rail Integrity Task Force 

ROC Receiver Operating Characteristic 

RSA Rail Seat Abrasion 

RSAC Railroad Safety Advisory Committee 

RSIA Rail Safety Improvement Act of 2008 

RWP Roadway Worker Protection 

TGMS Track Geometry Measurement System 

TSS Track Safety Standards 

VTI Vehicle-Track Interaction 
1

Executive Summary 

BACKGROUND 

Section 403 of the Rail Safety Improvement Act of 2008 (RSIA) requires the Secretary of 

Transportation to conduct a study of the track inspection process. Specifically, Section 403 calls 

for the Secretary to conduct a study to determine whether the required intervals of track 

inspections for each class of track should be amended; whether track remedial action 

requirements should be amended; whether different track inspection and repair priorities or 

methods should be required; and whether the speed at which railroad track inspection vehicles 

operate and the scope of the territory they generally cover allow for proper inspection of the 

track, and whether such speed and appropriate scope should be regulated by the Secretary. 

This report describes a study conducted by the Federal Railroad Administration (FRA), on behalf 

of the Secretary, in response to the requirement in Section 403 of the RSIA. The FRA Office of 

Railroad Safety prepared this report with assistance from FRA’s Office of Railroad Policy and 

Development and the Volpe National Transportation Systems Center. FRA’s Office of Railroad 

Safety is responsible for promoting and regulating safety nationwide throughout the railroad 

industry. The Office of Railroad Safety formulates and issues regulations under Title 49 Code of 

Federal Regulations (CFR). These regulations specify minimum safety requirements for track, 

equipment, communications systems, and other aspects of the railroad industry and 

infrastructure. 

The current report focuses on aspects of track inspection. Regulations pertaining specifically to 

track safety are found at 49 CFR Part 213, commonly referred to as the Track Safety Standards 

(TSS). The TSS define nine different classes of track, with Class 9 being the highest quality 

track and Class 1 being the lowest. For each class of track, the TSS prescribe various standards 

for track components, including ties, rail, fastening systems, and ballast. The TSS also prescribe 

inspection intervals for each class of track. All classes of track must be visually inspected by an 

authorized track inspector either on foot or in a hi-rail vehicle. In addition to visual inspections, 

the TSS also prescribe the use of several automated inspection systems; the number, type, and 

frequency of different automated inspections depend on the class of track. 

STUDY METHODS 

In order to successfully fulfill this Congressional mandate, FRA believed it was necessary to 

obtain a “snapshot” of the current track inspection process. A survey of a random sample of 

actively working track inspectors, as well as interviews with labor union officials and various 

levels of railroad management, provided the necessary information. 

FRA also compiled data related to track defects identified by FRA track inspectors over a 4-year 

period (2006–2009). These data provide an indication of the most prevalent defects as well as 

those that industry track inspectors fail to identify. In addition to the collection of survey data, 

interview data, and FRA track defect data, an “ideal observer” model was constructed for visual 

track inspection. The ideal observer model provides a theoretical upper limit, based on 

previously compiled empirical data, on how well the best possible observer can perform. The 
2

primary purpose of the “ideal observer” model is to have a baseline against which current 

inspection speeds reported in the survey can be compared. 

RESULTS 

Survey data indicates that nearly all railroad track inspectors are initially trained through on-thejob training, but half also have formal classroom training. The vast majority of track inspectors 

(85 percent) work 8-hour days and 10 percent reported working 10-hour days. Survey results 

indicate that track inspectors frequently work beyond the scheduled workday. Over half 

indicated that in the month prior to the survey, they had worked—on a rest day—an average of 

three times. 

The inspector’s job involves inspecting track either from a hi-rail vehicle or on foot. On average, 

inspectors spend 5 hours per day doing inspections. The remainder of their day is devoted to job 

briefings, waiting for track time, travel, and reporting inspection results. Survey respondents’ 

territory size averaged slightly less than 80 miles. The reported number of miles inspected per 

day varies depending upon the extent to which the hi-rail vehicle is used, the number of curves 

on the track, and whether the track is jointed or continuous welded rail (CWR). The reported hirail speed varied from 5 mph to 30 mph, depending on the type and condition of the track being 

inspected. The ideal observer analysis generally suggested that speeds reported by track 

inspectors through the survey are adequate. 

The survey asked respondents to indicate how they typically identify various track defects. 

Nearly 10 percent rated two conditions as not readily detectable: rail seat abrasion and torch-cut 

or burned-bolt hole in rail. About a third of respondents indicated that they use track geometry 

measurement systems (TGMS) to aid them in identifying areas with track geometry related 

defects. 

Inspector comments on non-inspection duties were the most prevalent, and reflected that such 

tasks often take time away from their primary track inspection duties. Inspectors also 

commented about difficulties getting adequate track time for conducting inspections. 

Interviews with labor union officials emphasized the need for standardized training. Union 

officials also reported that there is pressure to do more work in less time. Both union officials 

and railroad management indicated that, given adequate time, visual inspection can find most of 

the track safety issues but automated systems are an essential tool for guiding and focusing the 

visual inspection process. 

Review of FRA track defect data revealed that defects related to turnouts, rail joints, crossties, 

and switches/frogs were, respectively, those most commonly found by FRA track inspectors and 

therefore those most likely missed by the railroad track inspector. 
3

RECOMMENDATIONS 

The data collected and analyses conducted indicate that improvements in the current track 

inspection process require further investigation of the following issues: 

 Expanded use of automated inspection systems to supplement visual inspections. 

 Standardization of track inspector training. 

 Maximum speed of track inspections being conducted from a hi-rail vehicle. 

 Alleviation of oftentimes punitive railroad operating practices and culture with respect to 

the track inspection process. 

Expanded use of automated inspection systems, beyond those currently prescribed in the TSS, 

will help alleviate the problem of missed defects that could cause derailments. Increased use of 

automated inspection systems would provide the opportunity for inspectors to conduct more 

thorough visual inspections at problem areas identified by the automated inspection systems thus 

helping to prevent a defect from causing a derailment. Track inspectors performing visual 

inspections cannot readily or easily detect certain track defects; according to the survey, torch cut 

bolt holes and rail seat abrasion (RSA) of concrete ties are on the top of the list. Torch cutting is 

now a prohibited practice, and various automated systems are available or in the design stages to 

detect RSA. 

Both the interviews with labor union officials and the survey data identified standardization of 

training as an issue. The FRA is aware of the general non-uniformity in training practices and 

will consider establishing formal guidelines and a skeleton curriculum that will establish 

minimum training requirements. 

There is no general, industry-standard operating speed for hi-rail vehicles used in track 

inspection. Sections 213.233(b) and 213.365(b) of Title 49 CFR do provide that if a vehicle is 

used for visual inspection, the speed of the vehicle may not be more than 5 mph when passing 

over track crossings and turnouts; otherwise, the inspection vehicle speed shall be at the sole 

discretion of the inspector, based on track conditions and inspection requirements. While labor 

union officials contend that 20 mph is reasonable as a general standard, this may not be 

appropriate for certain track conditions necessitating detailed inspections. FRA would prefer to 

focus more on ways to achieve efficient and effective inspections rather than on establishing a 

general, maximum inspection speed. Using various models such as the ideal observer and the 

collection of empirical data will provide information to evaluate if the current speeds, as reported 

by track inspectors, are sufficient to detect common defects visually. 

Survey and interview participants expressed concerns about railroad operating practices and 

safety culture. Pressure to complete work, dispatcher decisions, and inadequate track time are 

factors that can be alleviated by changes in railroads’ operating practices. Also non-inspection 

duties assigned to track inspectors limit the time they have available for track inspections. 

Implementation of a safety reporting system is one means to address these issues and to begin to 

change the safety culture in the maintenance-of-way departments. This approach would provide 

a confidential, non-punitive, and anonymous way for employees to report near-misses and other 

safety risks, such as management pressure to either ignore or downplay the severity of identified 

track defects. 
4

The FRA will research solutions to these issues and present the results to the Railroad Safety 

Advisory Committee (RSAC) for formal consideration. The RSAC provides a continuing forum 

for advice and recommendations to FRA on rulemakings and other safety-related program issues, 

enabling FRA to carry out its regulatory responsibilities for railroad safety more effectively. The 

RSAC includes representation from all of the agency’s major stakeholder groups: both large and 

small passenger and freight railroads, labor organizations, States, suppliers and manufacturers, 

and other interested parties, such as the National Transportation Safety Board (NTSB). The 

RSAC allows these groups to work cooperatively in developing the best solutions to safety 

issues, including identifying regulatory options to implement solutions where regulation appears 

necessary. The RSAC process will result in recommendations on whether updates to current 

FRA safety regulations are necessary for the issues raised in Section 403 of RSIA. 
5

1. Introduction 

Section 403 of the Rail Safety Improvement Act of 2008 (RSIA), formally Public Law 110-432, 

Div. A., requires the Secretary of Transportation to conduct a Track Inspection Time Study. 

Appendix A contains a complete copy of Section 403 of the RSIA. The study is to determine 

whether the required intervals of track inspections for each class of track should be amended; 

whether track remedial action requirements should be amended; whether different track 

inspection and repair priorities or methods should be required; and whether the speed at which 

railroad track inspection vehicles operate and the scope of the territory they cover allow for 

proper inspection of the track. 

The Federal Railroad Administration (FRA) believes that the intent of Section 403 of the RSIA 

is to address the overall effectiveness of the track inspection process as it currently exists, and to 

investigate ways to improve the process. To address the requirements of Section 403 of the 

RSIA, FRA—on behalf of the Secretary and through a neutral, third-party contractor—

conducted a survey of railroad industry track inspectors, as well as interviews with various levels 

of railroad and union management. The purpose of FRA’s survey-and-interview approach was 

to obtain a “snapshot” of the current state of the track inspection process. This was necessary in 

order to gain information about the duties of railroad track inspectors and the characteristics of 

the territory for which they are responsible. In addition, an understanding of the overall 

effectiveness of the current inspection process, and which aspects of the process could be 

improved, was sought. Furthermore, to address additional requirements of Section 403 of the 

RSIA, FRA has been participating in the Railroad Safety Advisory Committee’s (RSAC) Rail 

Integrity Task Force (RITF) of the Track Safety Standards Working Group, along with industry 

representatives. Recommendations concerning new regulations for rail integrity remedial 

actions, as well as the frequency of inspections for internal rail flaws, are being developed in the 

RITF. 

Currently, Title 49 Code of Federal Regulations (CFR) Part 213, Track Safety Standards (TSS), 

contains requirements that FRA believes necessary to maintain safe track and a stable, viable rail 

network. These standards are minimum safety standards. The TSS define nine classes of track, 

Class 1 being the lowest quality track and Class 9 being the highest. The TSS also prescribe the 

maximum operating speed for freight and passenger operations for each class of track. In 

addition, the TSS permit a track classification below Class 1; this track is called “excepted track” 

over which limited operations are allowed under special conditions. The TSS define discrete 

allowable limits for certain track characteristics. These limits comprise threshold levels that 

depend on the class of track. Generally, more stringent (restrictive) limits are imposed for higher 

track classes. When threshold levels are exceeded, the track has an FRA track “defect.” When a 

railroad learns that it is not in compliance with the TSS (for example, when a track defect exists), 

it must: 

 Remediate the defective condition such that the track is now in compliance with the TSS; 

 Reduce maximum train speed, thereby temporarily lowering the class of track to one for 

which the track condition does not exceed the allowable limits; or 

 Remove the track from service. 
6

The TSS are broken down into Subparts A–G, as shown in Table 1. Subparts A–F generally 

address track classes 1–5. Specifically, Subpart A addresses general issues such as prescribing 

maximum track speeds for Classes 1–5, as well as designation of qualified personnel, penalties, 

and waivers. Subparts B–D address requirements for various components of the track structure, 

track substructure support, and surrounding wayside area. Subpart E is smaller in scope and 

addresses the application of derail devices. Subpart F addresses inspection requirements, 

including frequency of inspection and inspection recordkeeping. Specifically, Subpart F 

addresses the requirements for inspection of rail for internal defects as well as other automated 

inspection techniques. Subpart G generally combines all of the subjects addressed in 

Subparts A–F and modifies each for application to Track 6–9. Subpart G is often referred to as 

the “high-speed standards.” 

Table 1. Subparts of Track Safety Standards 

Subpart Title Track Classes 

A General 1–5 and 6–91

B Roadbed 1–5 

C Track Geometry 1–5 

D Track Structure 1–5 

E Track Appliances and 

Track-Related Devices 1–5 

F Inspection 1–5 

G Train Operations at Track 

Classes 6 and Higher 6–9 

In addition to FRA track component requirements contained in Subparts B–D for track 

classes 1–5 and portions of Subpart G for track classes 6–9, many railroads have internal 

standards for various track integrity parameters, including track geometry, sizing of internal rail 

defects, and visual assessment of track components. These internal standards are often more 

stringent than the TSS. Railroads generally deem these internal standards necessary, as they 

recognize that the FRA standards are minimum safety standards. Many railroads’ internal 

standards are implemented using a two-level strategy. The first level is a maintenance threshold. 

This threshold is more restrictive than the FRA standards. A second-level threshold, which is 

often referred to as a safety level threshold, is more critical than a maintenance level threshold. 

Internally, a railroad may set its safety level threshold at the FRA minimum safety standard level 

or slightly more stringent than the FRA minimum safety standard, depending on the preferences 

and operating practices of the particular railroad. 

In order to maintain a safe rail network, the TSS specifically prescribe several mandatory 

inspection techniques and procedures, including routine visual track inspections.2

 The TSS also 

address threshold safety levels for several automated inspection systems, including internal rail 

flaw, track geometry, and gage3

 restraint measurement systems (GRMS). 

 

1

 49 CFR Sections 213.2, 213.3, and 213.15 directly apply to Classes 6–9, as well. 

2

 Throughout this document, the term “visual inspection” will refer to an inspection performed by a human. This is 

not to be confused with “machine-vision inspection,” which refers to an automated inspection using machine-vision 

technologies. 

3

 “Gage” refers to the lateral distance between the two rails comprising a section of track. 
7

This report will use the FRA TSS as a baseline for evaluating the results from the survey. In 

addition, the report will briefly address potential changes to the TSS in order to improve the 

effectiveness of the visual and automated aspects of the track inspection process. 
8

2. Track Inspection Background and Methodology 

2.1 Defective Track Conditions Addressed in the Track Safety Standards 

The goal of the inspection process is to prevent incipient failure of the railroad track and the 

resulting derailment potential of a rail vehicle. The current standards for the various track 

components in the TSS are divided into three primary sections for track classes 1–5: roadbed 

(Subpart B), track geometry (Subpart C), and track structure (Subpart D). Portions of Subpart G 

address similar requirements for track classes 6–9. Subpart B prescribes standards for the 

roadbed. This section briefly addresses the issues of water drainage and excessive vegetation. 

Excessive vegetation presents a fire hazard and can obstruct the visibility of railroad signs and 

signals. Standing water can result in a softened roadbed that does not provide sufficient support 

for the track structure, including the rails, ties, and ballast. Subpart C prescribes standards for 

track geometry parameters, including track gage and cross-level, as well as vertical and lateral 

deviations of each rail. These components include ballast, crossties, rails, rail joints, anchors, 

and fasteners. Finally, Subpart D prescribes the standards for each of the critical components 

that comprise the track structure. The roadbed and track structure sections primarily address 

issues that can be evaluated visually. Track geometry is one measure of the overall condition of 

the track structure. Degraded track geometry may be the result of defective conditions that can 

be detected visually, such as those addressed in the roadbed and track structure sections. 

However, degraded track geometry can also result from conditions that are not visible on the 

surface. For example, internally rotted wooden ties, abrasion on the bottom surface of concrete 

ties, or poor subgrade conditions may not be initially detectable by visible means, but if these 

conditions exist in excess, then degraded track geometry will result when the track is loaded by a 

rail vehicle. Track geometry, therefore, can be thought of as a means for quantifying the overall 

condition of the track structure and substructure. 

2.2 Prescriptive vs. Performance-Based Thresholds 

In any field where safety is an issue, different inspection philosophies and approaches exist. The 

field of railroad track inspection is no exception. Inspection threshold levels (the limits beyond 

which a condition is considered defective) are established using one of two approaches: 

1) prescriptive; and 2) performance-based. Subparts B and C, respectively addressing roadbed 

and track structure, generally contain prescriptive standards. Prescriptive standards can be 

considered ones that describe a particular condition, such as an “ineffective tie.” Prescriptive 

standards are sometimes referred to as “hard standards.” Hard standards describe conditions that 

are discrete, meaning the condition is either there or not there. An example is a missing spike. 

“Hard conditions” are generally easier to detect visually; therefore, visual inspections are often 

used to detect such conditions. Hard conditions may be somewhat subjective, however, and may 

require a person’s judgment, such as identifying when a tie is “ineffective.” 

Performance-based standards, such as the track geometry standards in Subpart D, generally 

require quantitative measurements. As a result, they are typically less subjective, although they 

are still subject to measurement errors introduced by human error or imperfect machine sensors. 

Generally speaking, prescriptive standards are more suitable for visual inspections, while 
9

performance-based standards are more suitable for automated inspection systems, which are 

capable of accurately and efficiently taking measurements separated uniformly in space (such as 

every foot) or in time (such as every millisecond). It would require an exorbitant amount of time 

for an inspector to continually take such frequent, uniform measurements. 

Performance-based measurements are suitable for detecting “soft conditions.” Unlike a hard 

condition, described previously, the term soft condition refers to a condition that takes on a 

continuum of values. Therefore, a soft condition is always there, and the number of values it can 

take on is infinite. To make the idea of a soft condition less abstract, one can think of gage 

measurement as a soft condition. As long as there are two rails, gage will always exist and can 

take on any value. Due to the measurement that is required to quantify the severity of a “soft 

issue,” it is often more practical to use mechanized systems to detect such issues. This can be 

evidenced by the widespread popularity of automated track geometry measurement systems 

(TGMS). 

2.3 Probability of Detection Theory 

Whether prescriptive or performance-based, the TSS identify which conditions must be sought 

and remediated when found. The TSS generally provide a threshold safety limit, an inspection 

frequency, and a remedial action to alleviate each such undesirable condition. The threshold 

safety limit is generally more quantifiable for performance-based standards. The performance of 

an inspection system, whether mechanized or visual, can be characterized by its probability of 

detection (POD) of targeted conditions. This POD may vary based on the magnitude and type of 

defect. For example, given a uniform inspection speed, the probability that an inspector will 

visually detect a completely broken-through joint bar is greater than the probability that the 

inspector will detect an intact joint bar with a hairline surface crack. The POD of a specific type 

of defect can be quantified for humans and automated systems. 

A “perfect system” can be defined as one that finds all defective conditions and has no false 

positives (commonly referred to as “false alarms”) or false negatives (commonly referred to as 

“misses”). Through a formal presentation of POD theory, it can be shown that the “perfect” 

system does not exist because every system has inaccuracies or noise associated with it. Due to 

the presence of noise, a criterion line (or threshold value) must be set. Setting the criterion line 

at a practical level for a given system is critical. A criterion line that is set too leniently has the 

potential to produce a large number of false alarms. Generating many false alarms for a 

particular system may not be a drawback, as it may take a trivial amount of time to follow up and 

verify whether a “positive” detection is a false alarm or an actual defective condition. However, 

in other cases, where verification may take longer, a high number of false alarms may not be 

practical due to the cost associated with having to continually follow up and verify each alarm. 

At the same time, setting the criterion line more stringently will lead to fewer false alarms, but 

may lead to an increased number of misses. The number of misses that is acceptable for a 

system depends on the frequency of inspection and the rate of deterioration of the condition the 

system is intended to detect. If a system is being used very frequently or if the condition being 

detected is known to change slowly over time, then a high number of misses may be acceptable. 

However, if a system is being used infrequently or if the condition being detected deteriorates 

rapidly, then a high number of misses is not desirable. 
10

A receiver operating characteristic (ROC) curve is a common way of graphically displaying a 

system’s ability to detect defects accurately. It shows that detection of true defective conditions 

co-vary with false alarms. This is a very important characteristic of any inspection system: 

increases in the system’s true detection rate will increase the number of false alarms. Figure 1 

shows two ROC curves. The hypothetical system represented by the red ROC curve is better at 

detecting defects than the hypothetical system represented by the green ROC curve. 

Figure 1. Examples of ROC curves 

2.4 Remedial Actions 

Once a defective condition is found, the remedial action required will depend on how rapidly the 

given condition is expected to deteriorate. This rate of deterioration can be based on past 

empirical data, it can be the result of extensive physical modeling, or it can be a combination of 

both. Generally, the remedial actions specified in the TSS fall into one of three categories: 

replace, repair, or reduce. “Replace” refers to a complete replacement of the defective 

component with an equivalent, non-defective component. “Repair” deals with a temporary or, in 

some cases, permanent fix or modification to the defective component. For example, once an 

internal rail defect is indicated and verified to exist, 49 CFR § 213.113 provides that operation 

over the defective rail is not permitted until the rail is replaced or remedial action specified in a 

table is taken. “Reduce” refers to a reduction in speed. In order to defer repairing or replacing a 

defective condition immediately upon discovery, a railroad may opt to reduce the operating 

speed over the defective condition. Such a reduction in speed is often referred to as a “slow 

order.” A reduction in maximum speed to that corresponding to a class of track for which the 

condition is not a defect constitutes remedial action. This option is equivalent to the previous 

two options in the sense that it reduces the overall safety risk associated with a derailment. The 

repair and replace options are meant to minimize risk by restoring the track structure and 

preventing a derailment. On the other hand, the reduction-in-speed option is meant to minimize 

risk by reducing stress on the track, as dynamic forces generally are reduced as train speeds are 

reduced. The reduction-in-speed option also seeks to minimize damage in the event of a 

0

0.2

0.4

0.6

0.8

1

0 0.2 0.4 0.6 0.8 1

Probability of True Positives

Probability of False Positives
11

derailment, as historical evidence shows that damage severity and costs resulting from a 

derailment are reduced as operating speed is reduced. A number of remedial actions specified in 

the TSS do not fit exclusively into one of the three categories above, but rather may constitute a 

combination of two or three options. For example, the remedial action table in 49 CFR 

§ 213.113 calls for repairs or reduction in speed, depending on the type of defect detected and 

the time elapsed before remedial action is taken. 

2.5 Frequency of Inspection 

The combination of POD—determined from known visual or automated inspection system 

performance—and the rate of deterioration of the defective condition determines the required 

frequency of inspection. In some cases, the ideal frequency of inspection may not be feasible. 

For example, some systems, such as internal rail defect detector cars, operate slower than 

revenue train traffic. Using such systems frequently may cause extensive revenue losses; 

therefore, the practical frequency of inspection may involve finding a balance between safety 

concerns and economic viability. 

The TSS prescribe frequency of inspection requirements for visual inspections as well as several 

automated inspection systems for all classes of track. The frequency requirements for visual 

inspections are addressed in Subpart F (49 CFR § 213.233) for track classes 1–5 and in 

Subpart G (49 CFR § 213.365) for track classes 6–9. Required frequencies for automated 

inspection techniques can also be found in the TSS. For example, frequency requirements for 

internal inspection of rail on track classes 1–5 are addressed in Subpart F (49 CFR § 213.237), 

while Subpart G (49 CFR § 213.339) does the same for track classes 6–9. More details on 

frequencies of inspection provided in the TSS are presented in Section 3.4 of this report. 
12

3. Current Track Inspection Practices and Procedures 

The railroad industry currently uses a number of procedures and practices to maintain a safe rail 

network. Some of these procedures, including visual inspections and several automated 

inspection techniques, are required by the TSS for certain classes of track. However, other 

automated systems exist besides those addressed in the TSS, and these are used voluntarily by 

many railroads. The industry also uses various types of wayside monitoring systems. These 

wayside monitoring systems are primarily fixed at certain locations either on or near the track, 

while automated inspection systems traditionally refer to systems installed and used on a moving 

platform.4 Sections 3.1, 3.2, and 3.3 outline various practices and procedures, both manual and 

automated, that are currently used by the railroad industry. Section 3.4 describes which of these 

procedures are required by the TSS, as well as the threshold levels and required inspection 

frequencies for each method in inspection. 

3.1 Visual Inspections 

The railroad industry currently conducts regularly scheduled visual inspections. These visual 

inspections are either conducted on foot or in a hi-rail vehicle.5 An inspection may be conducted 

by a single inspector or multiple inspectors. For example, if multiple tracks are being inspected 

from a hi-rail vehicle, two inspectors may conduct the inspection together; therefore, each can 

focus his or her attention on a single track. 

Inspectors are expected to look for all track defects addressed in the TSS. Some of the defects 

that they find, such as excessively decayed ties, may be readily apparent even to a track 

inspection novice. On the other hand, other track defects are more subtle and require vigilance 

and proper training in order to be detected. For example, loose bolts on joint bars normally 

cannot be seen from a hi-rail vehicle; however, an experienced inspector can often detect a loose 

joint from the sound that is generated as the hi-rail vehicle traverses the joint. 

Detecting an ineffective fastener system or rail seat abrasion (RSA) is another example of a 

defective track condition that requires a track inspector with specialized skills. Oftentimes, 

directly seeing such a condition from a hi-rail vehicle can be difficult or impossible, but the 

ineffective fastener or RSA can sometimes be detected through other indirect, visual cues. When 

a loaded rail car traverses such a defect, there may be a tendency for the rail to roll slightly, 

resulting in a shift of the tread line on the rail. A trained inspector will be able to notice such a 

shift in the tread line on the rail and, after ground verification, will be able to attribute it to the 

proper defective condition. There are many other examples of a track inspector’s ability to 

detect track defects from non-obvious visual cues. 

 

4

 Throughout this document, automated systems implemented on a moving platform will be referred to as inspection 

systems, while wayside automated systems will be referred to as monitoring systems. 

5

 A hi-rail vehicle refers to a self-propelled vehicle that is manufactured to meet Federal Motor Vehicle Safety 

Standards and is equipped with retractable flanged wheels so that the vehicle can legally be used on both roads and 

rails. The name comes from combining “highway” with “rail.” A common alternative spelling is “high-rail.” 
13

3.2 Automated Inspection Systems 

In addition to visual inspections, the railroad industry uses a variety of automated inspection and 

monitoring systems. These systems are often more efficient at finding the “soft conditions,” 

such as track geometry deviations, discussed in Section 2.2 of this report. Over the past couple 

of decades, three primary inspection systems have emerged and been adopted by the industry: 

internal rail inspection, track geometry inspection, and gage restraint measurement systems 

(GRMS). The purpose of internal rail inspection is to detect rail flaws which develop inside the 

rail. Such flaws are not detectable from a visual inspection of the rail surface. Internal flaws 

develop for various reasons, and they often initiate at high-stress areas, such as the rolling 

contact interface between the wheel and rail. As the rail experiences repeated cyclical loading, 

these small initiation cracks grow in size and will eventually result in a complete rail break (also 

known as a service failure) if not detected and removed from the track. Undetected internal 

flaws pose a serious risk to the railroad. An undetected defect can result in rail failure causing 

disruption of service and the potential risk of catastrophic consequences such as derailment. In 

fact, in 2008, there were 9,759 rail breaks on Class I railroads6

 with 132 of the incidents resulting 

in train derailments.7

To maximize rail life, railroads use strategic processes that minimize service failure occurrences, 

relying on periodic ultrasonic or induction rail testing and strategic renewal of rail that shows 

obvious evidence of fatigue. Traditionally, ultrasonic techniques are predominantly used to 

detect internal rail defects, although devices operating on induction principles serve as 

supplemental, add-on systems to detect defects that may be missed by ultrasonic-based systems. 

Ultrasonic techniques consist of a mechanical means for striking the rail, which introduces sound 

waves that travel through the rail. Historically, the mechanical means constitutes a transducer 

containing a vibrating crystal, but recently systems relying on laser technologies have been 

developed. Then, receivers are used to receive reflected sound waves. The received sound 

waves are analyzed to determine whether or not a defect is present. With sufficient transducers, 

processing power, and operator expertise, the size and orientation of the defect may also be 

determined. 

A second type of inspection system used widely in the railroad industry is a TGMS. Track 

geometry generally characterizes the vertical and lateral deviations of each of the rails as well as 

the gage and cross-level measurements, which are, respectively, the horizontal and vertical 

relationships between the two rail heads. Maintaining proper gage and cross-level is essential, as 

gage or cross-level that is too large or small could result in a derailment. The vertical and lateral 

deviations of each of the rails are also important, as poor vertical and lateral alinement8

 can 

result in high dynamic forces and, potentially, a derailment. Track geometry generally 

 

6

 The term “Class I railroad” refers to a large railroad company. Class I status depends on operating revenue. In the 

United States, there are eight Class I railroads: National Railroad Passenger Corporation (Amtrak); BNSF Railway 

Company; Canadian National Railway Company; Canadian Pacific Railway; CSX Transportation, Inc.; Kansas City 

Southern Railway Company; Norfolk Southern Railway Company; and Union Pacific Railroad Company. The term 

“Class I railroad” does not have any relation to track classes 1–9 in the TSS. 7

 These 132 derailments were reportable events because the total damage amount for each derailment exceeded a 

threshold set by FRA’s railroad accident/incident reporting regulations (49 CFR Part 225). The number of nonreportable derailments is not known. 

8

 “Alinement” refers to the horizontal (or lateral) deviation of a rail from a reference plane. 
14

characterizes the health of the track structure. Non-standard gage and lateral deviation values 

can be indications of poor lateral restraint, which is often the result of failed ties and/or rail 

fasteners. Likewise, non-standard cross-level and vertical deviation values can be the result of 

degraded ties, ballast, and foundation support. While manual methods can measure gage and 

cross level as well as vertical and lateral alinement, automated measurement is more efficient 

and accurate. Furthermore, automated measurements supplied by a TGMS are obtained by 

applying a load on the track. As a result, a TGMS measures loaded geometry, which is more 

desirable, as it shows the ability of the track to withstand a significant vertical load. While 

manual measurements can take into account evidence of movement under load, manual 

measurements do not apply a vertical load on the track and, therefore, do not provide the same 

degree of insight into how the track may be deformed by a load. For these reasons, automated 

measurement of track geometry has become more widely used over the past couple of decades. 

Most of the major railroads have specially equipped railcars, typically called “track geometry 

cars,” on which they implement an automated TGMS. These cars can record accurate 

measurements of track geometry on a foot-by-foot basis, making them much faster and more 

economical when compared to manual collection of track geometry data. Railroads usually 

deploy their track geometry cars one to three times per year over a given section of track. Some 

lines, such as those with high tonnage as well as those that carry passenger and hazardous 

materials, often receive inspection priority over lower-tonnage, lower-value lines. 

GRMS is a third type of inspection system that is used widely in the railroad industry. GRMS 

measures the ability of the track structure to maintain its gage under a constant, vehicle-applied 

gage-spreading load; by doing so, it quantifies the strength of a track’s gage. GRMS vehicles 

include a third axle that applies a constant lateral, as well as vertical, load on each of the rails. 

GRMS typically measures the gage at two points: the first near the third axle and the second 

several feet away at an unloaded point. Based on the applied loads, the gage strength is then 

quantified by comparing the loaded and unloaded gage measurements. Measurement of gage 

strength, through the use of GRMS technology, allows railroads to effectively focus their tie and 

fastener replacement programs. 

Other systems are used by the railroad industry, but their use is not as extensive as internal rail 

defect detection systems, TGMS, and GRMS. Ground penetrating radar (GPR) systems use 

electromagnetic waves to capture information on different layers of the track structure, including 

ballast and sub-structure layers. GPR systems are capable of identifying moisture content, 

subgrade discontinuities, and other anomalies at various depths in the track structure which could 

result in poor support as the track settles; as a result, GPR allows for detection of subsurface 

track structure issues before they are manifested on the surface in the form of poor track 

geometry. 

Systems based on machine-vision inspection technologies to detect anomalies in the track 

structure are gaining in popularity. These machine vision systems use automated algorithms for 

extraction of designated features from high resolution 2D images or from 3D light detection and 

ranging (LIDAR) data. One of the systems that has increased in popularity in the past several 

years captures high resolution images of joint bars and uses automated algorithms to detect 

surface cracks. Currently, images of the flagged joint bars are visually reviewed by a human 

operator, as well, to determine that the joint bar does indeed contain a surface crack. This human 
15

review remains an essential part of most machine-vision systems, as automated algorithms for 

extraction of many features are still being developed and refined. Over time, the amount of 

human review required will likely decline. 

Another system that has recently gained in popularity uses multiple accelerometers to measure 

accelerations at various points on both the rail car body (above the suspension) and on the truck 

(at or below the suspension). These systems are generally referred to as vehicle/track interaction 

(VTI) systems. The acceleration measurements from the truck provide an indication of the 

dynamic forces that are being input into the track structure. As such, sections of track with 

repeated high acceleration measurements are likely to experience accelerated rates of 

deterioration. Furthermore, the accelerometers on the car body can be used for non-safety 

related functions, such as quantifying ride quality. 

3.3 Monitoring Systems 

Several types of monitoring systems are used by the rail industry. These systems are mounted on 

or near the track, rather than being mounted on a moving platform. Some of these systems 

monitor the health of the track, while others are typically used to monitor equipment condition. 

Wheel impact monitoring devices for the identification of wheel-flats are an example of 

equipment monitoring. There are other types of equipment monitoring devices, but they will not 

be discussed further here; rather, this section will focus on wayside devices that monitor the 

health of the track structure. Perhaps the most common type of wayside track monitoring device 

are those that measure longitudinal stress in rails as well as the temperature of the rail and use 

these two measurements to calculate the rail neutral temperature. Over the past couple of 

decades, continuous welded rail (CWR) has become increasingly used by the railroad industry. 

CWR consists of rail segments of 400 feet or more that are welded together to form one 

continuous rail that can span several miles. CWR allows for a smoother ride and lower track 

degradation rates when compared to jointed rail. However, the risk of buckling in track with 

CWR increases as the temperature of the rail increases; this is due to the thermal expansion 

properties of rail steel. To combat this issue, railroads attempt to raise the neutral temperature of 

rails at installation. This is accomplished either by thermal heating or mechanical pulling of the 

rails. These practices allow for higher rail temperatures to occur before the rail experiences 

compression forces. The temperature at which there is zero longitudinal rail stress is called the 

rail neutral temperature. Monitoring the rail neutral temperature is important, as this temperature 

can change (and generally decreases) after installation of the rail. The risk of buckling will 

increase as the rail temperature rises above the rail neutral temperature. Railroads are installing 

rail neutral temperature monitoring devices in increasing numbers. These devices use strain 

gages and rail temperature measurements to calculate the rail neutral temperature. Their primary 

purpose is to monitor and report when the rail neutral temperature falls below a desired level 

since the risk of buckling is increased as the rail neutral temperature decreases. 

Installation of rail neutral temperature monitoring devices on rail in service can be problematic 

as most units require that the rail be cut during installation in order to establish the reference 

neutral temperature. Therefore, some railroads have adopted the approach of installing rail 

temperature measurement monitoring devices. Such devices simply monitor the temperature of 

the rail. They are easier to install than rail neutral temperature monitoring devices, but the 
16

drawback is that the railroad must estimate the current rail neutral temperature, perhaps based on 

the amount of heating and/or tension put in the rail at installation as well as historical data on the 

reduction of rail neutral temperatures over time. As a result, the combination of the measured 

rail temperature and the educated guess at the rail neutral temperature permit estimation of the 

buckling risk. 

3.4 Track Safety Standards Inspection Requirements 

3.4.1 Visual Inspections Required by the Track Safety Standards 

The industry currently conducts routine visual inspections which are required by the TSS. 

Specifically, Subpart F (49 CFR § 213.233) of the TSS addresses the requirements for track 

classes 1–5, while Subpart G (49 CFR § 213.365) addresses track classes 6–9, which typically 

would support passenger operations. The TSS prescribe that the visual inspection should be 

conducted by qualified personnel, either on foot or in a vehicle. However, the TSS also 

encourage the use of automated technologies to supplement the visual inspection. Relevant 

portions of 49 CFR § 213.233, paragraphs (b) and (c), specifying the inspection procedures and 

frequencies for track classes 1–5 are reproduced here: 

(b) Each inspection shall be made on foot or by riding over the track in a vehicle at a 

speed that allows the person making the inspection to visually inspect the track 

structure for compliance with this part. However, mechanical, electrical, and other 

track inspection devices may be used to supplement visual inspection. If a vehicle is 

used for visual inspection, the speed of the vehicle may not be more than 5 miles per 

hour when passing over track crossings and turnouts, otherwise, the inspection 

vehicle speed shall be at the sole discretion of the inspector, based on track 

conditions and inspection requirements. When riding over the track in a vehicle, the 

inspection will be subject to the following conditions – 

(1) One inspector in a vehicle may inspect up to two tracks at one time provided 

that the inspector’s visibility remains unobstructed by any cause and that the 

second track is not centered more than 30 feet from the track upon which the 

inspector is riding; 

(2) Two inspectors in one vehicle may inspect up to four tracks at a time provided 

that the inspector’s visibility remains unobstructed by any cause and that each 

track being inspected is centered within 39 feet from the track upon which the 

inspectors are riding. 

* * * 
17

(c) Each track inspection shall be made in accordance with the following schedule – 

Class of Track Type of Track Required Frequency 

Excepted track and Class 1, 2, 

and 3 track 

Main track and 

sidings 

Weekly with at least 3 calendar days 

interval between inspections, or before use, 

if the track is used less than once a week, or 

twice weekly with at least 1 calendar day 

interval between inspections, if the track 

carries passenger trains or more than 10 

million gross tons of traffic during the 

preceding calendar year. 

Excepted track and Class 1, 2, 

and 3 track 

Other than main 

track and sidings 

Monthly with at least 20 calendar days 

interval between inspections. 

Class 4 and 5 track ........................... Twice weekly with at least 1 calendar day 

interval between inspections. 

* * * * * 

Section 213.365 of 49 CFR prescribes visual inspection requirements for track classes 6–9. 

Relevant portions of paragraph (b) of 49 CFR § 213.365 are identical to those restated above for 

paragraph (b) of 49 CFR § 213.233. Paragraph (c) of 49 CFR § 213.365 prescribes inspection 

frequency requirements, and is restated here: 

(c) Each track inspection shall be made in accordance with the following schedule – 

Class of Track Required Frequency 

Class 6, 7, and 8 track Twice weekly with at least 2 calendar days 

interval between inspections. 

Class 9 track Three times per week. 

Although not an entirely visual inspection in nature, paragraph (f) of 49 CFR § 213.365 requires 

a pilot train be run over Classes 8 and 9 track in certain cases: 

(f) In track classes 8 and 9, if no train traffic operates for a period of eight hours, a train 

shall be operated at a speed not to exceed 100 miles per hour over the track before 

the resumption of operations at the maximum authorized speed.

A visual inspection encompasses many elements of the track structure. These items are 

addressed in Subparts B, C, and D of the TSS for the lower track classes (Classes 1–5) and in 

portions of Subpart G for the higher-speed track classes (Classes 6–9). Subpart B addresses the 

roadbed and surrounding wayside area drainage and vegetation requirements. Subpart C 

addresses track geometry requirements. Visual inspection for geometry is acceptable for track 

classes 1–6. However, for Classes 7 and above, automated inspection for geometry deviations is 

required and will be discussed in more detail in subsequent sections. Finally, Subpart D 

generally addresses ballast, crosstie, and fastener system requirements. 

Visual inspections and automated inspections typically occur on a regularly scheduled basis. 

However, unscheduled visual inspections, commonly referred to as special inspections, also 

occur. Oftentimes, these special inspections are the result of severe weather conditions but may 

also be the result of a derailment or passenger ride quality complaints. Section 213.239 of the 

TSS addresses the need for special inspections. Specifically, it states the following: 
18

In the event of fire, flood, severe storm, or other occurrence which might have damaged 

track structure, a special inspection shall be made of the track involved as soon as 

possible after the occurrence and, if possible, before the operation of any train over that 

track. 

3.4.2 Automated Inspections Required by the Track Safety Standards 

As mentioned previously, some of the automated systems used by industry are required by the 

TSS for certain classes of track. Typically, an automated inspection required by the TSS also 

requires on-the-ground verification of a defective condition to verify potential “false positive” 

defect indications resulting from automated system errors. There are five automated inspection 

techniques prescribed in the TSS for which this ground verification technique is required. First, 

requirements for internal rail inspections are described in Section 213.237 of the TSS for 

Classes 1–5. Paragraph (a) of 49 CFR § 213.237 is restated here: 

(a) In addition to the track inspection required by § 213.233, a continuous search for 

internal defects shall be made of all rail in Classes 4 through 5 track, and Class 3 

track over which passenger trains operate, at least once every 40 million gross tons 

(mgt) or once a year, whichever interval is shorter. On Class 3 track over which 

passenger trains do not operate such a search shall be made at least once every 30 

mgt or once a year, whichever interval is longer. 

Section 213.339 of the TSS describes internal rail inspection requirements for Classes 6–9. 

Paragraph (a) of 49 CFR § 213.339 is restated here: 

(a) A continuous search for internal defects shall be made of all rail in track at least 

twice annually with not less than 120 days between inspections. 

Rail inspection requirements for Classes 1–5 are currently under review. Since 2007, the RITF 

has been meeting to recommend regulatory language changes to 49 CFR §§ 213.233 and 

213.237. The RITF comprises industry and government representatives, and is a subset of 

RSAC’s Track Safety Standards Working Group. FRA believes that the recommendations 

arising from this RSAC effort will address the requirements of Section 403(b) of the RSIA, 

which requires that the Secretary review the most current rail flaw, rail defect growth, rail 

fatigue, and other relevant track or rail-related research and studies and respond with necessary 

recommendations. 

The RITF has discussed factors that can and should be included in determining the frequency of 

internal rail flaw testing and a methodology for taking those factors into consideration with 

respect to mandatory test intervals. In these discussions, the focus has been on the validity of the 

time intervals and accumulated tonnage limits, which determine the current required rail test 

frequency. In addition, consideration has been given to recent studies concerning defect 

development. The challenge to the railroads is to avoid the occurrence of service failures 

(broken rails) due to undetected defects. Inspecting for and removing rail defects reduces the 

likelihood of derailments, helps maximize rail service life, and protects service reliability. Given 

the performance limits of modern rail flaw detection equipment, rail testing frequency is the 
19

most effective means for controlling risk. A railroad must choose a rail testing frequency that 

will balance the cost of testing and defect removal with the expected derailment cost to minimize 

the net cost of the risk. In this delicate equation, the reliability and efficiency of the testing 

system play an important role. 

The second automated inspection technique addressed in the TSS is a TGMS inspection. Section 

213.333 of the TSS prescribes requirements for automated inspection of track geometry for track 

classes 7 and higher. Specifically, paragraph (a) of 49 CFR § 213.333 reads as follows: 

(a) For track class 7, a qualifying Track Geometry Measurement System (TGMS) vehicle shall be 

operated at least twice within 120 calendar days with not less than 30 days between 

inspections. For track classes 8 and 9, it shall be operated at least twice within 60 days with 

not less than 15 days between inspections. 

GRMS is the third automated inspection technique addressed in the TSS. Paragraph (h) of 

49 CFR § 213.333 prescribes GRMS inspection requirements for Classes 8 and 9, stating: 

(h) For track classes 8 and 9, a qualifying Gage Restraint Measurement System (GRMS) 

shall be operated at least once annually with at least 180 days between inspections to 

continuously compare loaded track gage to unloaded gage under a known loading 

condition. The lateral capacity of the track structure shall not permit a gage 

widening ratio (GWR) greater than 0.5 inches. 

In addition to the requirements for Classes 8 and 9, an alternative standard using GRMS is 

provided for Classes 1–5 in Section 213.110 of the TSS. The prescriptive, non-performancebased standard for gage strength is contained in 49 CFR § 213.109. Paragraph (c) of that section 

states the following: 

(c) Each 39 foot segment of: Class 1 track shall have five crossties; Classes 2 and 3 track 

shall have eight crossties; and Classes 4 and 5 track shall have 12 crossties, which 

are not: 

(1) Broken through; 

(2) Split or otherwise impaired to the extent the crossties will allow the ballast to 

work through, or will not hold spikes or rail fasteners; 

(3) So deteriorated that the tie plate or base of rail can move laterally more than 

1⁄2 inch relative to the crossties; or 

(4) Cut by the tie plate through more than 40 percent of a ties’ thickness. 

As an alternative to this prescriptive standard, a railroad may choose to designate certain track as 

GRMS-territory, in which case the track does not have to comply with 49 CFR § 213.109. 

Instead, GRMS-designated track for track classes 1–5 is regulated under 49 CFR § 213.110 of 

the TSS. Paragraph (a) of that section states: 

(a) A track owner may elect to implement a Gage Restraint Measurement System 

(GRMS), supplemented by the use of a Portable Track Loading Fixture (PTLF), to 
20

determine compliance with the crosstie and fastener requirements specified in 

§§ 213.109 and 213.127 provided that – 

(1) The track owner notifies the appropriate FRA Regional office at least 30 days 

prior to the designation of any line segment on which GRMS technology will 

be implemented; and 

(2) The track owner notifies the appropriate FRA Regional office at least 10 days 

prior to the removal of any line segment from GRMS designation. 

The fourth automated inspection required by the TSS concerns acceleration measurement 

requirements. Specifically, relevant portions of paragraphs (j) and (k) of 49 CFR § 213.333 state 

the following: 

(j) At least one vehicle in one train per day operating in Classes 8 and 9 shall be 

equipped with functioning on-board truck frame and carbody accelerometers. * * * 

(k) For track classes 7, 8 and 9, an instrumented car having dynamic response 

characteristics that are representative of other equipment assigned to service or a 

portable device that monitors on-board instrumentation on trains shall be operated 

over the track at the revenue speed profile at a frequency of at least twice within 60 

days with not less than 15 days between inspections. The instrumented car or the 

portable device shall monitor vertically and laterally oriented accelerometers placed 

near the end of the vehicle at the floor level. In addition, accelerometers shall be 

mounted on the truck frame. 

The threshold safety limits for the measured accelerations are not reproduced here but can be 

found in the table of Vehicle/Track Interaction Safety Limits in Section 213.333 of the TSS. 

The usage of instrumented wheelsets for the measurement of dynamic forces is the fifth 

automated inspection required by the TSS. Paragraph (l) of 49 CFR § 213.333 states in relevant 

part the following: 

(l) For track classes 8 and 9, an instrumented car having dynamic response 

characteristics that are representative of other equipment assigned to service shall be 

operated over the track at the revenue speed profile annually with not less than 

180 days between inspections. The instrumented car shall be equipped with 

functioning instrumented wheelsets to measure wheel/rail forces. * * * 

The threshold safety limits for wheel/rail forces are not reproduced here but can also be found in 

the same table cited above. 

3.4.3 Summary of Inspections Required by the Track Safety Standards 

Table 2 summarizes the visual and automated inspections required by the TSS as well as the 

maximum operating speed for passenger and freight trains for each class of track. Automated 

inspection techniques are highlighted in light blue in Table 2. With the exception of periodic 

inspections for rail defects, automated inspection requirements exist exclusively for track classes 

6 and above. 
21

Table 2. FRA track inspection requirements for each class of track 

3.5 FRA’s Role 

FRA’s Office of Railroad Safety serves, among other things, as an independent quality check on 

the railroad industry. FRA’s Office of Railroad Safety includes eight regional offices in addition 

to a headquarters office located in Washington, DC. Each regional office includes a number of 

specialists, including a track specialist. The track specialist typically supervises 8 to 12 track 

inspectors per region. Due to the limited number of FRA track inspectors, FRA is generally 

limited to conducting “spot-check” visual inspections which serve as a quality check on the 

railroad industry’s track inspection processes and personnel. The locations chosen for these FRA 

spot-check inspections are determined by the National Inspection Plan (NIP), which is a safety 

plan formulated and updated annually by FRA’s Office of Railroad Safety. The purpose of the 

NIP is to optimize FRA’s ability to reduce the rates of various types of train accidents, releases 

of hazardous materials, and casualties from human factor errors. The plan provides guidance, 

based on data-driven models, to each regional office on how its inspectors should divide their 

work by railroad and State. This is accomplished using data collected during visual inspections 

and under FRA’s Automated Track Inspection Program (ATIP). ATIP is aimed at automated 

collection of track data. Currently, ATIP uses four railcars capable of collecting geometry data 

and a fifth car that is capable of collecting both geometry data and GRMS data. ATIP 

management is located primarily at FRA headquarters in Washington, DC. However, the data 

collected is disseminated to the respective regional offices and FRA track inspectors. These 

inspectors may use the data to focus their track inspection spot-checks. 
22

4. Results of Study 

This section contains the results of the track inspector survey, highlights from the interviews 

with railroad management and labor union officials, the results from a theoretical model of 

observer detection accuracy, and data on defects identified by FRA inspectors. 

4.1 Track Inspector Survey Results 

The track inspector survey results are presented in this section. Appendix B contains a copy of 

the survey form. The survey was mailed on April 19, 2010, to 661 track inspectors, and 

responses received by June 25, 2010, were included in the study results. 

4.1.1 Sample Size Methodology and Response Rate 

One of the most important issues in conducting the survey of track inspectors was to determine 

the sample size necessary to guarantee results that were reliable enough to meet the objectives of 

the study. In general, the larger the sample size, the greater the reliability of the resulting 

estimates, but this typically has to be traded off against the expense of a larger sample. It was 

determined that 95 percent confidence was adequate to obtain descriptive information about the 

track inspection process. Additionally, it was assumed that the estimate should be within 

7.5 percent of the “true” value (i.e. a range of 15 percent). There are an estimated 2500 track 

inspectors working in the United States. The only practical way of reaching these individuals is 

through their labor organization, the Brotherhood of Maintenance of Way Employes9

 Division 

(BMWED). Inspectors at one of the eight Class I railroads are not members of BMWED, so 

reaching this group was not feasible; however, the track inspectors for the seven remaining 

Class I railroads are represented in the survey results. BMWED provided a list of 1536 actively 

working track inspectors who were candidates to participate in the survey. The following 

formula was used to calculate the necessary sample size: 

  2 2 2

2 2

 1 



z V N

z NV

n

x

x

where z is the reliability coefficient (1.96 for 95 percent confidence level); N is the population 

size; ε is the error tolerance; and Vx is the unknown population variance. 

The derivation of this formula will not be presented here, but can be found in the literature (Levy 

et al.). From above, it is seen that z, N, and ε have already been defined; their respective values 

are 1.96, 1536, and 0.15. In order to solve the equation for the sample size (n), an estimate of a 

population variance (Vx) for a parameter of interest must be obtained. In this study, primary 

parameters of interest are a track inspector’s ability to approximate the time spent doing specific 

tasks, speed of inspection, and distance traveled during an inspection. For the purposes of 

determining a sample size, at least one of these parameters had to be estimated. It was decided 

that the sample size would be based on an inspector’s ability to estimate distance traveled. This 

 

9

 This is an alternative spelling of the word “employee” and is the spelling preferred by BMWED. 
23

parameter was chosen instead of the time and speed parameters primarily because empirical 

estimates of population variance for estimating distance traveled were found in previous studies 

(Boff et al., pp. 896–897). Based on this study, the population variance for estimation of 

distance traveled was 1.18. It can be reasonably expected that population variance for estimation 

of distance traveled among track inspectors would be less than 1.18 due to the presence of 

distance markers, such as mileposts. Therefore, it can be assumed that using a population 

variance value of 1.18 was a conservative estimate of variance and that actual variance among 

track inspectors would be less than this value. 

In accordance with the above formula, a sample size of 205 would be adequate to ensure valid 

results. Previous surveys of this railroad population achieved a response rate of 31 percent 

(Gertler 2006). To assure an adequate number of valid surveys, assuming this response rate, a 

random sample of 661 track inspectors was chosen. After final count, survey responses totaled 

237, yielding a response rate of 36 percent. 

4.1.2 Potential Survey Biases 

As noted previously, the survey was mailed on April 19, 2010, and responses received by 

June 25, 2010, were included in the survey results. A number of questions in the survey asked 

respondents to indicate how often they performed a particular task in the past month. Therefore, 

FRA acknowledges that some survey responses may have biases due to the time of year that the 

survey was conducted. For example, the spring season often sees increased issues related to 

ballast fouling due to seasonal rain as well as melting snow. Also, rail maintenance de-stressing 

operations are performed in the spring. Rail de-stressing operations refer to the adjustment of 

rail neutral temperature by cutting a rail and placing it in tension; performing this activity 

reduces the risk of buckling throughout the summer. Furthermore, it is also reasonable to expect 

a lessening of special inspections due to extreme heat and/or cold during the spring season. For 

at least these reasons, FRA acknowledges that slight biases may exist in the survey; however, the 

majority of the data is still applicable to general track inspection issues, without regard to the 

time of year. 

4.1.3 Experience 

The number of years of experience as a track inspector varied, and a histogram of the frequency 

of responses is shown in Figure 2. The mean number of years as an inspector is 12.3, and the 

median is 14.0. Due to the asymmetry of the distribution, the median may be a better measure of 

central tendency in this case. 
24

Figure 2. Number of years as a track inspector 

The number of years that each of the respondents had spent on their current territory also varied. 

Figure 3 shows a histogram of the frequency of responses. The mean number of years on an 

inspector’s current territory is 10.9, and the median is 7.0. Once again, due to the asymmetry of 

the distribution, the median may be a better measure of central tendency. 

Figure 3. Number of years on current territory 

The mean and median for the histogram in Figure 3 are lower than the mean and median for the 

histogram in Figure 2. This is a strong indication that inspectors typically will change territories 

at least once during their track inspection careers. 

0

2

4

6

8

10

12

14

16

18

Percentage of Respondents

Years

0

2

4

6

8

10

12

14

16

18

20

22

Percentage of Respondents

Years
25

4.1.4 Initial and Subsequent Training 

A question addressing initial track inspection training was presented in a multiple choice format 

with respondents instructed to select all that apply. Approximately 90 percent of respondents 

had some form of on-the-job training as their initial training, and approximately 53 percent of 

respondents had formal, company training as an introduction to the track inspection process. 

A followup question was asked related to subsequent training. The responses are summarized in 

Figure 4. While periodic training on the FRA TSS is not required training, over two-thirds of 

respondents stated that they are provided with FRA TSS training either every year or every other 

year. Nearly 75 percent of respondents stated that they receive FRA safety standards training 

every year, yet FRA believes that most respondents were likely referring to FRA roadway 

worker protection (RWP) training, which is mandatory annual training under 49 CFR 214. Some 

respondents gave a brief description of “other track related training” that they had received; there 

were a number of different types of training mentioned, but the two predominant responses were: 

 Formal training related to longitudinal track stability (including CWR and track buckling 

training) 

 Training via lessons learned from random audits conducted by either direct supervisors or 

other management officials 

Figure 4. Subsequent track inspection training 

4.1.5 Supervisory Oversight 

Respondents were asked to indicate how frequently, in the past year, their track supervisor 

accompanied them on an inspection. The results are presented in Figure 5. Nearly 70 percent of 

respondents indicated that their supervisor accompanied them quarterly or more frequently. 

0%

10%

20%

30%

40%

50%

60%

70%

80%

Percentage of Respondents

On‐the‐job

FRA track standards

FRA safety standards (e.g.

roadway worker

protection)

Other track‐related

training
26

Figure 5. Frequency of supervisory oversight 

4.1.6 Length of Workday and Overtime Burden 

The survey asked respondents to indicate the official length of their workday. Nearly 85 percent 

of respondents indicated that they had an 8 hour workday with 10 percent indicating that their 

workday was 10 hours. The remaining 5 percent had scheduled workdays of either 8.5, 9, 9.5, 

12, or 14 hours. 

To determine the level of effort expended above and beyond one’s scheduled workday, the 

survey asked respondents to indicate how many days in the past month they worked more than 

the scheduled length of their workday. The results are presented in Figure 6. Over half of the 

respondents indicated that in the past month they had worked overtime at least 1 day but not 

more than 10 days. The mean number of overtime days was 3.1 days and the median was 3.0 

days. 

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

50%

Monthly Quarterly Less Frequently No Answer

Percentage of Respondents
27

Figure 6. Number of days in the past month worked more than scheduled 

length of workday 

To further determine the amount of additional effort expended above-and-beyond one’s 

scheduled workday, respondents were asked to indicate how many times in the past month they 

worked on a non-scheduled workday (also referred to as a rest day). The results are presented in 

Figure 7. Approximately a quarter of respondents said that they did not work on a rest day. The 

remaining respondents worked on one or more rest days with over 50 percent of respondents 

indicating that they worked on 1 to 3 rest days. Both the mean and median number of rest days 

worked was 3.0. 

Figure 7. Number of rest days worked in the past month 

0%

5%

10%

15%

20%

25%

30%

35%

None 1 to 5 6 to 10 11 to 15 More than

15

No answer

Percentage of Respondents

Number of Days

0%

5%

10%

15%

20%

25%

30%

None 1 2 3 4 5 More

than 5

No

answer

Percentage of Respondents

Number of Days
28

4.1.7 Time Allocation 

In an effort to determine how track inspectors allocate their time throughout the day, respondents 

were asked to indicate the number of hours that they spend performing inspection duties and 

repair duties on a typical day. The results are shown in Figure 8. The mean and median for track 

inspection time are both 5.0 hours, and the mean and median for repair duties is 1.9 hours and 

2.0 hours, respectively. 

Figure 8. Time spent performing inspection and repair duties 

Additionally, respondents were asked to indicate how much time they spend doing each of the 

following activities on a typical day: job briefings; reporting inspection results; travel time; 

waiting for track time. The results are indicated in Figure 9. The median reported interval for 

“job briefings” is 16 to 30 minutes, and the median reported interval for “travel time,” “waiting 

for track time,” and “reporting inspection results” is 31 to 45 minutes. The “travel time” and 

“waiting for track time” parameters have larger standard deviations than “job briefings” and 

“reporting inspection results.” This is an indication that the time spent performing activities 

other than inspection and repair varies widely between inspectors. 

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

1 2 3 4 5 6 7 8 9 10 11

Percentage of Respondents

Time (hours)

Inspection duties

Repair duties
29

Figure 9. Time spent performing other activities (besides inspection and repair) 

4.1.8 Total Territory Size 

In order to determine the amount of track for which an inspector is responsible, respondents were 

asked to indicate the number of mainline track miles in their territories. The histogram in 

Figure 10 indicates the distribution of the results. The data indicates a mean of 78.9 miles and a 

median of 75.0 miles. The term “track miles” was clearly defined in the survey. “Track miles” 

refers to total miles of track; for example, 10 miles of double track constitutes 20 track miles. 

Figure 10. Number of mainline track miles in territory 

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

50%

Percentage of Respondents

Time (minutes)

Job briefings

Reporting inspection

results

0%

2%

4%

6%

8%

10%

12%

14%

0 to 10

11 to 20

21 to 30

31 to 40

41 to 50

51 to 60

61 to 70

71 to 80

81 to 90

91 to 100

101 to 110111 to 120121 to 130131 to 140141 to 150

151 to 160

More than 160

No answer

Percentage of Respondents

Distance (miles)
30

4.1.9 Track Miles Covered Per Day 

Respondents were asked to indicate the number of miles of track they inspect on a typical day. 

The results are shown in Figure 11. FRA believes that data in the “More than 180” bin 

represents outliers which may be the result of respondents’ misinterpretation of the question. 

Figure 11. Number of track miles inspected on a typical day 

Each of the respondents indicated whether they inspect by: 1) hi-rail vehicle only, 2) hi-rail 

vehicle mostly and on-foot sometimes, 3) on-foot mostly and hi-rail vehicle sometimes, or 4) onfoot only. The data presented in Figure 11 was separated into these four categories. The number 

of respondents in each group, as well as the mean and standard deviation for each group, is 

shown in Table 3. 

Table 3. Primary method of visual inspection 

Count Mean 

(miles per day) 

Standard Deviation 

(miles per day) 

Hi-rail only 14 79.1 43.3 

Hi-rail mostly, on-foot 

sometimes 

163 64.8 31.6 

On-foot mostly, hi-rail 

sometimes 

17 10.4 8.0 

On-foot only 12 9.2 5.8 

4.1.10 Inspection Speed 

To determine typical inspection speeds, the survey asked respondents who use hi-rail vehicles to 

indicate the speed of their inspection on tangent CWR track10 and tangent jointed track, as well 

as on curves. Figure 12 shows that the speed distributions for tangent jointed track and curves 

(the second and third bars in each category) are very similar with approximately 50 percent of 

 

10 In the railroad industry, the term “tangent track” is commonly used to refer to track that is straight. 

0%

5%

10%

15%

20%

25%

30%

Percentage of Respondents

Distance (miles)
31

respondents indicating that they travel at a speed of 11 to 20 mph and approximately 30 percent 

of the respondents indicating that they travel at a speed of 1 to 10 mph. On tangent CWR track 

(the first bar in each category), approximately 50 percent of respondents indicated that their 

average speed of inspection is between 21 to 30 mph and approximately 30 percent of 

respondents indicated that their inspection speed is 11 to 20 mph. The data depicted in Figure 12 

indicates that inspection speeds on tangent CWR track is typically higher than on tangent jointed 

track and curves. 

Figure 12. Reported hi-rail inspection speeds 

The survey also asked respondents to indicate conditions that cause the speed of inspection to be 

adjusted. The multiple choice options included: time pressure to complete work; weather; 

interlocks; inadequate track time; highway crossings; dispatcher decisions; other (please 

specify). The results are displayed in the histogram in Figure 13. Approximately 60 percent of 

respondents indicated that weather, time pressure to complete work, dispatcher decisions, and 

inadequate track time were all factors that cause variations in inspection speed; it is assumed that 

most of these variations would typically result in an increased average inspection speed. 

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

50%

55%

1 to 10 11 to 20 21 to 30 31 to 40 41 to 50

Percentage of Respondents

Speed (mph)

Tangent CWR

Track

Tangent Jointed

Rail

Curves
32

Figure 13. Conditions that cause adjustments to typical inspection speeds 

4.1.11 Detection of Track Defects 

The survey asked respondents to indicate how they typically identify various track defects. The 

results are shown in the table in Appendix C. Respondents were asked to indicate all the 

methods used to find each condition. In other words, for a given track condition, a respondent 

could mark off both “Visual – On foot” as well as “Visual – Hi-rail.” As a result, the numbers in 

each row will not necessarily sum to 100 percent. 

As the table in Appendix C indicates, RSA and burned bolt holes in rail had higher values of 

“Not Readily Detectable” relative to other track conditions. The practice of burned bolt holes in 

rail is no longer allowed, so the number of these occurrences in track is likely gradually 

decreasing. However, detection of RSA continues to be a problem. 

The table also indicates that approximately 30 to 35 percent of track inspectors use automated 

data from TGMS inspections in order to help direct them to areas with alinement and profile 

deviations, as well as gage and cross-level issues. This range of 30 to 35 percent of inspectors 

utilizing automated data is large relative to utilization of automated data to find non-geometry 

related track defects; most non-geometry-related track defects had 2 percent or less of 

respondents indicating that they use automated data to aid them in finding the defective 

condition. 

4.1.12 Calculated Inspection Speed 

As a validity check on the data, inspection speeds were calculated for those respondents who 

indicated that they inspected primarily by hi-rail and sometimes or rarely on foot. The calculated 

speed of inspection for each inspector in this group was determined by dividing the reported time 

spent inspecting on a typical day by the reported number of miles inspected. Figure 14 displays 

the results. The data has a mean of 13.9 mph and a median of 12.0 mph. The distribution of 

these values generally indicates slightly lower speeds than the distributions shown in Figure 12. 

0%

10%

20%

30%

40%

50%

60%

70%

Weather Time

pressure to

complete

work

Dispatcher

decisions

Inadequate

track time

Highway

crossings

Interlocks

Percentage of Respondents
33

However, the speeds shown in Figure 12 are values that inspectors reported for inspections on hirail vehicles. The calculated inspection speeds inherently include some time on foot for ground 

verification of potential defects and explains why these values are slightly lower than the 

reported hi-rail inspection speeds. 

Figure 14. Calculated inspection speeds 

4.1.13 Calculated Inspection Frequency 

Generally, the TSS require that track classes 1–3 be inspected at least once a week, and track 

classes 4 and 5 be inspected at least twice a week (for complete details, see Section 213.233 of 

the TSS). As a check on the data quality, as well as to determine approximate frequency of 

inspection, the inter-inspection time (the number of days between inspections) was calculated by 

dividing a respondent’s territory size (in track miles) by the number of track miles that the 

inspector covers on a typical day. The resulting number represents the number of days to cover 

the entire territory, assuming that only mainline track is inspected. The data is filtered to include 

only those individuals who inspect mostly by hi-rail and do not (or rarely) inspect by walking. 

Individuals whose responses indicate that they inspect more miles daily than the total number of 

mainline miles in their territory were excluded. 

Figure 15 indicates the frequency of inspection for those inspectors inspecting only track 

classes 1–3, and Figure 16 does the same for those inspectors inspecting only track classes 4 

and 5. As can be seen from the histogram distributions, the great majority of inspectors on 

Classes 4 and 5 cover their territory every 1 to 2 days, while inspectors on Classes 1–3 cover 

their territory every 1 to 3 days. These inter-inspection times generally are more frequent than 

the requirements prescribed in Section 213.233 of the TSS. In fact, according to the survey data, 

there are no cases where practiced track inspections frequencies do not comply with TSS 

requirements. 

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

50%

0 to 10 11 to 20 21 to 30 31 to 40 More than 40

Percentage of Respondents

Speed (mph)
34

Figure 15. Calculated inspection frequency for track classes 1–3 and excepted track 

Figure 16. Calculated inspection frequency for track classes 4 and 5 

4.1.14 Relevant Correlations 

Correlation coefficients are often used to find relationships between two (or more) random 

variables. A value of 0 indicates that there is no correlation between two variables, and a value 

of 1 indicates perfect correlation. A more complete explanation of correlation coefficients can 

be found in introductory books on statistics, such as Keeping (1995). 

For the purposes of this report, a correlation coefficient was calculated to determine if there is a 

correlation between an inspector’s territory size and speed of inspection. A correlation 

coefficient of 0.5 was calculated; therefore, as territory size increases, speed of inspection will 

generally increase. This relationship is visually evident in the scatter plot shown in Figure 17. 

The territory size here refers to track miles, not route miles. If a route mile dataset were 
35

available from the survey, one would expect an even stronger correlation than is shown in the 

scatter-plot in Figure 17. 

Figure 17. Correlation of number of mainline track miles and inspection speed 

4.1.15 Summary of Track Inspectors’ Comments 

The final portion of the survey asked respondents to comment on any other aspect of the track 

inspection process that they would like FRA to consider in preparing its report to Congress. Of 

the 237 completed surveys, 74 included comments. The topics addressed in the comments varied 

widely; however, four subjects were brought up frequently: 

 Non-inspection duties (11 comments) 

 Maintenance (7 comments) 

 Track time (6 comments) 

 Hours of service (5 comments) 

Comments on non-inspection duties were the most prevalent. Respondents indicated that they 

often had to perform duties not directly related to visual track inspection, such as riding in 

internal rail defect detector cars, participating in hi-rail geometry car pilot programs, and 

directing surfacing gangs. They said that doing such tasks often takes time away from their 

primary track inspection duties. 

The comments relating to maintenance generally stated that the railroad does not have enough 

maintenance crews and equipment to perform all the necessary repairs. A couple of the 

comments directly stated that the inspection process is not the major issue; rather, manpower to 

fix the problems found was identified as the primary cause for concern. 

Comments addressing track time pointed out that it is not uncommon for an inspector to get 

forced off the track due to dispatcher decisions. This results in increased inspection speeds in 
36

order to get over an assigned territory, or it results in a portion of the territory not getting 

inspected. One comment summarized the issue by stating that almost all personnel in the 

railroad want to get trains moving across a given territory at as fast a speed as possible, while the 

job of the track inspector is to slow down (or completely stop) traffic if an unsafe condition 

exists. Due to the perceived lost revenue from this reduced traffic flow, inspectors oftentimes 

have trouble getting track time because increased track time may result in an increase in the 

number of slow orders. 

Comments that were directed towards the “hours of service” issue generally stated that track 

inspectors often have to work excessive hours of overtime. In many cases, this overtime 

(whether paid or unpaid) may not be desired by a track inspector; however, it is oftentimes 

required by the railroad. Respondents commented that track inspectors can, in certain 

circumstances, be expected to work 16 to 20 hours a day; therefore, one comment referred 

specifically to the hours of service laws for roadway worker protection and suggested that similar 

hours of service laws should exist for track inspection. 

4.2 Salient Points from Labor Union and Railroad Management Interviews 

To substantiate the responses in the track inspector survey and assure that a total picture of the 

track inspection process was obtained, phone interviews were conducted with labor union 

leadership and three levels of railroad management: track supervisors, division engineers, and 

chief engineers. Track supervisors (or roadmasters) are the direct supervisors of track inspectors. 

Typically 5–10 inspectors report to a single track supervisor. Division engineers are often the 

direct supervisors of track supervisors. Track supervisors are in charge of a subdivision; whereas 

division engineers are in charge of an entire division, which is comprised of multiple 

subdivisions. Chief engineers (or system-level officers) are typically in charge of a railroad’s 

entire network or a substantial percentage of the network. Class I railroads typically have 1 to 4 

chief engineers. Chief engineers are usually the direct supervisors of division engineers. Unlike 

the track inspectors, the individuals in each of these groups were not randomly selected; instead, 

the members of each of these groups constituted a convenience sample.11 This was necessary as 

the neutral, third-party contractor conducting the interviews was only given access to those labor 

union and railroad officials who had the available time to participate in the interview process. 

The purpose of conducting interviews with these various groups was to obtain different 

perspectives on the state of track inspection. FRA believed that information obtained during the 

interviews would provide additional context to survey responses. Detailed summaries of each of 

the interview groups are in Appendices D–G. 

Standardized training for track inspectors was a point emphasized by several labor union 

officials. In addition, union officials believe that track supervisors, rather than track inspectors, 

are currently not receiving enough training. They noted that railroads are hiring track 

supervisors that have no prior experience performing track inspection. This comment by labor 

union officials appears to be validated by data obtained from track supervisors during their 

 

11 A “convenience sample” (also known as an “accidental sample”) is a type of sampling not based on principles of 

probability but rather involves the sample being drawn from members of the population that are easily accessible or 

convenient. 
37

interviews, as seven out of twelve of the track supervisors interviewed had no prior track 

inspection experience; however, they may have had experience performing track maintenance 

duties. 

Labor union officials stated that there is pressure to do more work in less time. They said that 

this is partly due to the fact that in recent years there has been a trend toward increased noninspection duties, such as repair duties, for track inspectors. Labor union officials were split on 

whether there are enough track inspectors, but railroad officials (including track supervisors, 

division engineers, and system-level officers) generally agreed that there are enough track 

inspectors to maintain a safe, viable rail network. Still, five out of twelve track supervisors 

commented that their inspectors have to work overtime occasionally or frequently. The reasons 

most often cited were lack of track time and inclement weather. Therefore, railroad industry 

management appears to believe that the amount of work expected of track inspectors is 

reasonable; however, track supervisors realize that railroad operating practices, along with 

inclement weather conditions, may create the occasional or frequent need for overtime. 

Labor union officials commented that track inspectors oftentimes feel pressure, either real or 

perceived, from management not to issue slow orders, as slow orders may result in lost revenue. 

Inspectors are routinely faced with this decision of whether or not to issue a slow order, 

balancing safety and the desires of railroad management. Furthermore, even if a defect is 

reported and a slow order is issued, union officials said that there are generally not enough repair 

crews to fix all the issues that track inspectors find; similar comments were made by several 

track supervisors. As a result, track inspectors often have to prioritize track repairs. 

Several track supervisors provided comments on their interactions with FRA track inspectors. 

While some of the comments were positive, there were also negative comments. The negative 

comments tended to focus on the perception that FRA inspectors are, under certain 

circumstances, not very helpful when it comes to explaining and interpreting the FRA 

regulations to railroad personnel. One comment also addressed the lack of uniformity of some 

enforcement policies between different FRA regions. 

Based on the interview data, there does not appear to be common consensus on a recommended 

speed for inspections conducted from a hi-rail vehicle. Labor union officials advocate 20 mph 

for an effective inspection. Three of the six system-level officers interviewed said that their 

railroad does not have a recommended speed for hi-rail inspection; three indicated that they have 

a maximum inspection speed but did not provide an exact numerical value for this speed. 

Individual railroads typically prescribe a maximum hi-rail speed, for inspection or otherwise; a 

typical limit is 40 mph. 

There was general agreement that inspectors have the tools they need to conduct inspections. 

Both labor union officials and railroad management indicated that visual inspection can find 

most of the track safety issues. RSA was one of the conditions that was reported as hard-to-find 

through a visual inspection. 
38

There was general agreement that, given adequate time, the visual inspection process works and 

that automated systems are an essential tool for guiding and focusing the visual inspection 

process. 

4.3 Outputs from Ideal Observer Model 

FRA believes that there may be a correlation between speed of inspection and quality of 

inspection. Therefore, prior to conducting the survey, an ideal observer model was constructed 

for visual track inspection. The ideal observer model provides an upper limit on how well the 

best possible observer can perform by making optimal use of the information available from the 

stimulus. The purpose of the ideal observer model is to serve as a comparison to practices 

reported in the track inspector survey regarding speed at which visual track inspections are 

routinely performed. This section briefly discusses results of the ideal observer model. For a 

complete development of the ideal observer model, including derivations of the relevant 

equations, assumptions made during formulation, and limitations of the model, refer to 

Appendix H. 

The plot in Figure 18 represents the output of the model assuming that 95-percent detection 

accuracy is acceptable and assuming the ideal observer is searching for 16 items simultaneously; 

based on the number of different defects that railroad track inspectors routinely look for, it is 

assumed that 16 objects is a reasonable number to use in the ideal observer model. The plot 

indicates that the speed at which an accurate detection is possible depends upon the size of the 

objects to be detected. In the plot, it is assumed that all 16 objects that the ideal observer is 

searching for are of the same size. For example, if the ideal observer is searching for 16 1.5- 

inch-sized objects and 95 percent detection accuracy is desired, then a maximum speed of 

16.3 mph should be observed. 

Figure 18. Ideal observer output for a 16 object search with 95-percent detection accuracy 

0

5

10

15

20

25

30

35

0 0.5 1 1.5 2 2.5 3 3.5

Speed (mph)

Object Size (inches)
39

The inspector survey indicates that speed of track inspection ranges from 5 mph to 30 mph 

depending on the type and condition of the track being inspected. The mean calculated speed for 

those primarily inspecting by hi-rail was 13.9 mph. These values appear to correspond well with 

the output of the ideal observer model. As discussed above, the ideal observer suggests an 

inspection speed of 16.3 mph if 16 variable 1.5-inch-sized objects are being sought. Track 

inspectors are searching for various size objects, many of which are much larger than 1.5 inches, 

such as fouled ballast and excessive wayside vegetation. Furthermore, inspectors use auditory as 

well as visual signals to detect defective track conditions. For example, loose joints, rail 

mismatch, or other variation in the running surface often create a distinct audible noise when the 

hi-rail vehicle moves over them. In conclusion, the ideal observer analysis, therefore, generally 

suggests that current inspection speeds are adequate. 

4.4 Defects Found by FRA Track Inspectors 

To supplement the track inspector survey, FRA track defect data was compiled in order to 

determine the prevalent track defects identified in the field by FRA inspectors. The data was 

obtained from each of the eight FRA regions for a 4-year period (2006–2009). The number and 

type of defects found by FRA inspectors may provide information on the effectiveness and 

quality of the current inspection process. 

Figure 19 presents the results for each defect type arranged in descending order of percentage of 

the total number of defects identified. The data represents a total of 350,719 defects found and 

documented by FRA track inspectors between 2006 and 2009. The bars in Figure 19 are colorcoded to denote whether the defective condition is considered “hard” (blue) or “soft” (orange) in 

terms of the relative objectivity of the determination that the defective condition exists (as 

discussed in Section 2.2 of this report). 

Figure 19. Track defects identified by FRA track inspectors (2006–2009) 
40

Figure 19 clearly indicates that the predominant defects identified during this period were related 

to turnout, rail joint, and crosstie issues. Figure 20 shows the historical trends for these defects 

over the subject period and affirms that these conditions are the most frequently identified 

defects for each year. Each of these three defect types always account for more than 15 percent 

of the total number of track defects identified by FRA inspectors in a given year. Turnouts (and 

special trackwork generally) and rail joints are chronic problems for the railroad industry as these 

components are subjected to extreme loading from passing trains. 

Figure 20. Historical trend of most common defects identified by FRA track inspectors 

Turnouts allow trains to travel from one track to an adjacent track through a curve and a set of 

switches, and they are affected primarily by large lateral loads generated as the train negotiates 

the curve. When the loads become sufficiently large, the rail fastening system which keeps these 

components properly aligned can be overloaded and begin to fail. Degraded or weak fastening is 

the most frequent defective condition attributed to track turnouts and is considered to be “hard” 

implying that this condition is typically readily detectable by an inspector. 

Rail joints are equally problematic for railroads as they represent a “weak link.” Joints in track 

are necessary for many reasons (rail defect repair, electrical isolation of track sections for 

signaling purposes) and as such their deficiencies must be addressed. Wheel impact loads at the 

rail end gap in the center of the joint are the primary contributor to joint failure. Joint bars 

exhibit many failure modes including center cracks near the rail end gap, cracks emanating from 

bolt holes, as well as potentially more benign conditions such as missing or loose bolts. Bolthole cracks are the cause of the majority of derailments attributed to joint bar defects. In 

contrast, data collected by the FRA regarding results of on-foot inspections of joints in CWR 

under the requirements of Section 213.119 (as revised in 2006) indicate that a center-crack is the 

most common joint defect identified during such inspections. This disparity between condition 

and cause may suggest that bolt hole cracks are more difficult to detect visually. Nevertheless, 

joint defects are also considered “hard” or readily detectable conditions. 
41

Crosstie defects are the third most frequently identified defect by FRA track inspectors. This is 

not especially surprising since crossties exist in substantially greater numbers in track (one tie 

every 20 inches or so) than either turnouts or rail joints. Acknowledging this fact, FRA 

regulations related to crossties essentially focus on prescribing the number of “effective” ties that 

must exist in any 39-foot track segment and certain parameters related to permissible tie 

degradation. Notwithstanding the prescriptive (discrete or “hard”) aspects of the crosstie 

regulations, the determination whether a crosstie is defective is dependent upon an assessment of 

its “effectiveness” which, as described in Section 2.2 of this report, is a “soft” or more subjective 

evaluation. 

Further examination of Figure 19 suggests that with the exception of crosstie defects, all other 

“soft” conditions are small in number. By definition, confirmation of the existence of these 

defects often depends on judgment or reliance on automated means. Acknowledging the time 

and effort required to confirm the presence of certain of these defects (such as track geometry 

defects) and the fact that railroad track inspectors and FRA track inspectors apply the same 

techniques or methods as part of the visual inspection process, detection of these conditions may 

be challenging. 
42

5. Recommendations 

The track inspector survey, along with the interviews conducted with labor union officials and 

various levels of railroad management, provides a snapshot of the current track inspection 

process. The data collected facilitates focusing on certain aspects of the track inspection process 

for further investigation for the purpose of identifying how the effectiveness of track inspectors 

can be improved. This section describes four issues for consideration as improvements to the 

track inspection process: 

 Integration of visual and expanded automated inspections 

 Track inspector training 

 Speed of inspection 

 Railroad operating practices and culture 

5.1 Integration of Visual and Expanded Automated Inspections 

The first issue under consideration is the expanded use of automated inspection systems in the 

track inspection process. From the tabulation of responses to the track inspector survey 

questions regarding the typical means by which track inspectors identify FRA defects (see 

Appendix C), it is clear that data from such systems is increasingly being used (and possibly 

relied upon) by track inspectors. The table in Appendix C shows that at least 30 percent of 

respondents use automated data to find track geometry-related defects. 

Automated inspection techniques are described in Section 3.2 of this report and those required by 

FRA regulations are outlined in Section 3.4 and summarized in Table 2. Table 2 underscores the 

fact that automated track geometry measurements are required only for FRA track classes 7–9. 

Any other deployment of such systems by a railroad or track owner is elective. 

Figure 19 presents all the defects identified nationwide by FRA track inspectors between 2006–

2009. The findings suggest that, for this sample, the number of track geometry-related defects 

(track surface, gage) represents a small fraction. This can be construed to imply that either track 

geometry defects are relatively few in number generally, FRA inspectors rely on automated 

measurement systems for inspection of track geometry, or that FRA inspectors do not typically 

(due to the extent of territory for which they are responsible) invest the time required to make the 

numerous manual measurements necessary to confirm the existence of certain track geometry 

defects. If the latter is the case, it may also hold true for railroad track inspectors as well, 

especially when considering the fact that a majority (60 percent) of track inspectors indicated 

that pressure to complete inspections and limited track time were generally among the primary 

causes of adjustments to the speed at which they perform inspections. 

It is also evident that the track inspectors performing visual inspections cannot readily or easily 

detect certain track defects. The two track defects for which this is true, according to the survey, 

are highlighted in green in the table in Appendix C; they include torch cut bolt holes and RSA of 

concrete ties. Torch cutting of bolt holes is now a prohibited practice according to 49 CFR 

§§ 213.121(g) and 213.351(f), although some may still exist in track. The detection of a torch 
43

cut bolt hole is practically impossible without disassembly of the joint. RSA is equally difficult 

to detect visually, given the physical location of the defect and the position in which the 

inspector must place himself in order to view the affected area of the tie. 

Therefore, expanding the use of automated inspections already required by the TSS (such as 

TGMS inspections) would be beneficial in terms of improving inspection effectiveness by 

targeting inspection resources where needed, resulting in a corresponding safety improvement. 

If inspection burden can be lowered by supplementing the process with automated means, 

railroad track inspectors can more strategically apply limited track time and inspection and repair 

resources. FRA also believes that there could be significant safety benefits to using additional 

automated inspection systems not currently required by the TSS or which do not yet exist. 

Continued commitment to research and development efforts to identify and develop systems 

capable of detecting defects that are commonly missed by the visual inspection process (such as 

RSA) is essential. 

5.2 Track Inspector Training 

The second issue for consideration is training. Standardization of training was repeatedly 

identified as an issue by labor union officials. Furthermore, survey data indicates that the 

predominant form of initial track inspector training is on-the-job training; also, in the write-in 

portion of the survey, several inspectors commented that they would like to receive more formal 

training, rather than simply on-the-job training. FRA is aware of the general non-uniformity in 

track inspector training due to the excessive use of informal, on-the-job training. This nonuniformity may be due, in part, to the absence of specific FRA regulations or guidelines in this 

area. Historically, FRA has not played a direct role in the training and certification of industry 

track inspectors. Even presently, FRA does not envision being the sole authority to train and 

certify industry track inspectors. Rather, FRA will consider establishing formal guidelines and a 

skeleton curriculum that will establish minimum training requirements. These minimum training 

requirements will provide guidance to the railroads, as well as third-party trainers, and will help 

ensure uniformity in the track inspector training process. 

Formal track inspection training guidelines to be proposed by FRA may involve the development 

of new regulations similar to those presently recommended by RSAC’s RITF and Track Safety 

Standards Working Group for addressing rail integrity including minimum training requirements 

for operators of rail flaw detection equipment and a definition of a “qualified operator.” The 

Working Group’s recommended training requirements are presented in Appendix I in draft form 

and were accepted by the full RSAC body on September 23, 2010. 

5.3 Speed of Inspection 

The third issue is the speed of track inspection. There is generally no industry-standard 

operating speed for hi-rail vehicles used in track inspection. While labor union officials contend 

that 20 mph is reasonable, this may not be appropriate for certain track conditions for which 

detailed inspections are required. The speed at which track inspectors travel over their territories 

depends on many factors, including the age of the track, the amount of traffic it accommodates, 

and geographic conditions. If the establishment of such a speed limit were determined to be 
44

critical to improvement of the track inspection process, the formulation of the ideal observer 

outlined in Appendix H provides a sound analysis of the variables that come into play in human 

detection of various sized objects at different speeds. However, the empirical data and constants 

currently being used in the model can be thought of as generic in nature and certainly not 

specific to track inspection. Therefore, the speeds suggested by this model served as a quick 

reality check on the speeds reported by track inspectors and cannot be construed as optimized for 

the track inspection process. In order to gain the necessary empirical data on detectability of 

specific FRA defects both on foot and at different speeds in a hi-rail vehicle, it is necessary to 

conduct experiments on a test track with known defects. Only by doing this can the relationship 

between speed of inspection and detection accuracy be more conclusively determined. The setup 

and conduct of such experiments would require significant time and resources and this effort is 

deemed to lie outside the scope of this report. FRA believes that due to the vast number of 

variables (such as track condition, weather, and inspector experience) that affect an effective 

inspection speed, it may be counterproductive to set a maximum inspection speed. Rather than 

focus on maximum inspection speeds, FRA would prefer to focus more on how to achieve 

efficient and effective inspections. 

5.4 Railroad Operating Practices and Culture 

The final issue concerns railroad operating practices and safety culture. As the data and 

comments from the survey and interviews indicate, railroad operating practices often limit the 

amount of track time available to the track inspector. Specifically, in the survey data, it can be 

seen that three out of the top four reasons (namely time pressure to complete work, dispatcher 

decisions, and inadequate track time) for a track inspector’s change in speed of inspection are 

factors that, at least ideally, can be alleviated by changes in railroads’ operating practices. The 

comments from track inspectors, track supervisors, and labor union officials tended to support 

these survey data and point to the allegation that railroad operating practices in many cases limit 

track inspectors’ track time. Track inspectors also reported that over time they have been 

assigned increasing amounts of non-inspection duties that limit the time they have available for 

track inspections. In addition, the inspector’s ability to carry out safety-critical duties is often 

compromised by an industry safety culture that discourages the inspector from issuing slow 

orders. In these instances, safety is compromised in the interest of service goals. 

The implementation of a safety reporting system is one means to address these issues and to 

begin to change the safety culture in the maintenance-of-way department. Safety reporting 

systems provide a confidential, non-punitive, and anonymous way for employees to report nearmisses and other safety risks, such as management pressure to either ignore or downplay the 

severity of identified track defects. A report review team consisting of representatives from 

labor, management, and the regulator would meet periodically to review the reports and 

recommend solutions. The Aviation Safety Action Program for airline pilots and the Air Traffic 

Safety Action Program for Federal Aviation Administration air traffic personnel have been 

successful in identifying and resolving issues that otherwise might not have come to the attention 

of transportation industry management. The Confidential Close Call Reporting System (C3RS), 

a pilot implementation of a safety reporting system for the railroad industry, is experiencing 

similar successes, but to date, only train and engine service employees have participated. 
45

Because these systems require trust and cooperation among the stakeholder groups, ultimately 

they result in a shift in the safety culture of the organization. 

All four of these issues (including additional automated inspections, track inspector training 

standardization, speed of inspection, and railroad operating practices) will be formally 

considered and addressed through the RSAC process. 
46

Appendix A. 

Section 403 of the Rail Safety Improvement Act of 2008 (Public Law 

110-432, Div. A.) 

SEC. 403. TRACK INSPECTION TIME STUDY. 

(a) STUDY.—Not later than 2 years after the date of enactment of this Act, the Secretary 

shall transmit to the Committee on Transportation and Infrastructure of the House of 

Representatives and the Committee on Commerce, Science, and Transportation of the Senate a 

report containing the results of a study to determine whether— 

(1) the required intervals of track inspections for each class of track should be amended; 

(2) track remedial action requirements should be amended; 

(3) different track inspection and repair priorities or methods should be required; and 

(4) the speed at which railroad track inspection vehicles operate and the scope of the 

territory they generally cover allow for proper inspection of the track and whether such speed 

and appropriate scope should be regulated by the Secretary. 

(b) CONSIDERATIONS.—In conducting the study the Secretary shall consider— 

(1) the most current rail flaw, rail defect growth, rail fatigue, and other relevant track- or 

rail-related research and studies; 

(2) the availability and feasibility of developing and implementing new or novel rail 

inspection technology for routine track inspections; 

(3) information from National Transportation Safety Board or Federal Railroad 

Administration accident investigations where track defects were the cause or a contributing 

cause; and 

(4) other relevant information, as determined by the Secretary. 

(c) UPDATE OF REGULATIONS.—Not later than 2 years after the completion of the study 

required by subsection (a), the Secretary shall prescribe regulations based on the results of the 

study conducted under subsection (a). 

(d) CONCRETE CROSS TIES.—Not later than 18 months after the date of enactment of this 

Act, the Secretary shall promulgate regulations for concrete cross ties. In developing the 

regulations for class 1 through 5 track, the Secretary may address, as appropriate— 

(1) limits for rail seat abrasion; 

(2) concrete cross tie pad wear limits; 

(3) missing or broken rail fasteners; 

(4) loss of appropriate toeload pressure; 

(5) improper fastener configurations; and 

(6) excessive lateral rail movement. 
47

Appendix B. 

Track Inspector Survey 
48
49
50
51
52
53
54
55

Appendix C. 

Detection of Track Defects Through Visual Inspection1

,

2

Visual – 

On foot 

Visual – 

Hi-rail 

Data from 

Automated 

Inspection 

Not 

Readily 

Detectable 

Not 

Applicable

Gage dimension less 

than/greater than allowable 78.48% 36.29% 37.97% 1.69% 0.00% 

Alinement deviation 

exceeds allowable 51.48% 65.82% 33.33% 1.27% 0.84% 

Maximum crosslevel 

exceeds allowable 64.98% 54.43% 35.44% 0.42% 0.00% 

Runoff at end of raise 

exceeds allowable 58.65% 52.32% 30.80% 2.95% 1.69% 

Deviation from uniform 

profile on either rail 

exceeds allowable 

61.60% 55.27% 33.33% 1.69% 0.84% 

Difference in crosslevel 

(warp) exceeds allowable 67.51% 49.79% 37.97% 0.84% 0.00% 

Reverse elevation on curve 

exceeds allowable 63.71% 51.05% 33.76% 0.42% 1.69% 

Insufficient ballast 29.11% 85.65% 1.27% 0.00% 1.27% 

Fouled ballast 39.66% 80.17% 1.27% 0.42% 1.27% 

Ineffective/defective ties 83.97% 42.19% 2.11% 0.42% 0.42% 

Rail seat abrasion 73.00% 14.77% 3.38% 8.44% 8.86% 

Track constructed without 

crossties does not 

effectively support track 

structure 

60.76% 28.27% 2.11% 2.11% 19.83% 

Broken rail 56.96% 75.11% 15.61% 0.00% 0.00% 

Worn rail 71.31% 44.30% 16.03% 1.69% 0.42% 

Rail-end mismatch 75.53% 52.32% 0.42% 0.42% 0.00% 

Cracked or broken joint bar 88.61% 37.55% 1.27% 0.00% 0.00% 

 

1

 Rows highlighted in red represent defects in which at least 30 percent of respondents indicated that they use 

automated inspection data to assist them in locating the defective condition. 2

 Rows highlighted in green represent defects in which at least 5 percent of the respondents indicated that they 

cannot readily detect the condition during a visual inspection. 
56

Visual – 

On foot 

Visual – 

Hi-rail 

Data from 

Automated 

Inspection 

Not 

Readily 

Detectable 

Not 

Applicable

Insufficient number of joint 

bolts 57.38% 76.79% 0.42% 0.00% 0.00% 

Loose/worn joint bolts 82.28% 41.77% 0.42% 0.00% 0.84% 

Torch-cut or burned-bolt 

hole in rail 62.87% 5.91% 3.80% 8.02% 26.58% 

Stock rail/switch point not 

seated or functioning as 

intended 

98.31% 13.50% 0.42% 0.00% 0.42% 

Loose, worn, or missing 

switch components 97.05% 18.57% 0.00% 0.00% 0.00% 

Insufficient/ineffective 

fasteners 77.64% 40.93% 0.00% 0.00% 0.42% 

Insufficient anchors to 

restrain rail movement at 

turnouts or CWR 

83.97% 35.44% 0.00% 0.00% 0.42% 

Insufficient flangeway 

depth/width 97.05% 9.28% 0.42% 0.00% 0.84% 

Worn or defective frog/frog 

components 94.51% 22.78% 0.84% 0.00% 0.00% 

Heat kinks 28.27% 88.19% 0.42% 0.42% 1.69% 

Right-of-way obstructions 24.47% 88.61% 0.42% 0.42% 0.84% 

Object between base of rail 

and the bearing surface of 

the tie plate causing 

concentrated load 

87.34% 20.25% 0.42% 2.95% 1.69% 

Insufficient/defective tie 

plates 80.17% 34.18% 0.84% 1.69% 1.27% 

Missing or damaged 

signage 22.78% 87.76% 0.42% 0.00% 1.27% 

Track washouts 37.55% 83.54% 0.42% 0.84% 3.38% 

Poor drainage/pumping ties 54.85% 77.64% 1.27% 0.42% 0.42% 

Excessive vegetation 24.05% 89.03% 0.00% 0.42% 0.84% 

Defective derail 

condition(s) 78.06% 32.91% 11.39% 1.27% 0.42% 
57

Appendix D. 

Results of Interviews with Labor Union Officials 

Number of interviewees  5 general or vice chairmen 

 1 director of education and safety 

What types of inspection-related training does your membership receive from the railroad? 

The union officials confirmed that, in general, there is RWP training every year and some type of 

track standards training every other year. Initial training may vary across railroads or even on 

subdivisions within a railroad. Specific recommendations of union officials included: 

 Roadmasters are in need of more training, not the inspectors. Railroads have been hiring 

people out of college to be roadmasters, and they know nothing about the railroad or 

track inspection. Inspectors need someone, outside of the carrier, to call if there are 

questions. This could be an independent person who knows how FRA would react to a 

given situation. This needs to be a resource person who is not a regulator. 

 Training should be more standardized and there should be a schedule for retraining. 

Training should also include practical application, not just classroom activities. 

Mentoring should be a part of the training process. This would involve coupling an 

experienced inspector with a trainee for a period of time. There may be value in having 

FRA conduct the initial training. 

What factors hinder performing quality inspections? 

Note: Numbers in parenthesis in this Appendix indicate the number of comments regarding this 

factor over the total number of labor union officials interviewed. 

 Frequency of trains in this commuter operation makes it difficult to work when the 

inspector constantly has to watch for approaching trains while doing the inspection. (1/6) 

 Pressure to do more work in less time. One general chairman reported that there is 

pressure not to do overtime. (3/6) 

 Increasing amount of non-inspection duties (e.g., piloting a work train across the 

territory). (2/6) 

 Lack of support forces for repairs. (2/6) 

 Availability of track and time. (2/6) 

 Number of inspectors in the vehicle (should have two). (2/6) 

 Pressure to avoid a slow order. (2/6) 
58

What equipment would aid the track inspector in safely performing inspections? 

Overall, union officials thought the inspectors have the tools they need but they did offer a few 

suggestions: 

 Old style hi-railer without nose gives a better view of the track. 

 Device in hi-railer to detect elevation difference between rails would be helpful. Division 

engineers have these. 

How could the track inspection process be changed? 

Overall, union officials feel that, given enough time, the process works. One general chairman 

thought that bringing back the Track Inspection Playbook, that one of the Class I railroads used 

in the early 1990s, would be a big help to inspectors. 

What factors influence the speed at which the hi-railer operates during inspections? 

There is general agreement on the relevant factors, which are:

 Availability of track and time, which depends upon the frequency of trains. (4) 

 Length of the territory given the limited time; pressure to complete inspection on 

time. 

 Whether or not the inspector is inspecting for and reporting defects, or inspecting for 

and repairing defects. 

 Type of rail – slower for jointed rail than CWR. (2) 

 Number of joints that must be inspected. 

 Number of inspectors in the vehicle. (Lone inspector goes slower.) 

 Condition of the track. (2) 

 Speed varies depending upon what the inspector is looking for/at. 

 Inspectors looking only for heat kinks and, conversely, cold weather pull-aparts could 

average 30 mph if straight track. 

 Speed set by carrier. (2) 

 Pressure to complete inspection on time. 

BMWED advocates 20 mph maximum speed for an effective inspection. 
59

What types of automated inspections do your members find useful? In what way are they 

useful? 

There was general agreement on the value of automated inspections as follows: 

Type of inspection Responses 

Ultrasonic rail flaw detection Find internal defects before visible. 

GRMS 

Surrogate for finding rail seat abrasion. Best used as 

adjunct to visual inspection. Could be adapted to 

measure rail seat abrasion on concrete ties (due to 

moisture). 

PTLF 

Not a lot of benefit to the inspector. Visual inspection 

usually adequate. Provides non-subjective 

measurement. 

TGMS Guides inspection. Track inspector must get report 

and be trained on interpretation. 

VTI Not really a track inspector’s concern. Inspector looks 

at track only. 

Which track conditions are “not readily detectable” by the visual track inspection process? 

 Rail seat abrasion – track geometry car and GRMS could detect. 

 Loose/worn joint bars – from hi-rail can hear it, on foot more likely to detect. 

 Torch cut bolt hole – can only see it if remove joint bar. 

 Insufficient anchors – inability to measure stressors on the rail. 

What track inspection issues do your members bring to your attention? 

Each union official interviewed offered unique issues, except for length of territory where three 

people commented. 

 Length of territory: one comment about territory size being too large; two comments that 

territory size was appropriate. 

 Railroad only responds to automated inspection, not what the inspector says. 

 Tie conditions are corrected only to get them to hold gage. 

 Surface defects aren’t corrected. 

 Lack of repair staff is the biggest issue. 

 Lack of track time. 

 Management pressure; too much work pressure. 
60

 Main issue is criticism inspectors receive for doing their job. Track inspectors do not 

receive the support for doing a good job. 

 Upper management views track workers at side of tracks from passing train and assumes 

they are not working. Then, word comes from management that productivity is not 

adequate and there is pressure to do more. 

Do you feel that the railroad has an adequate number of inspectors to comply with current 

FRA requirements? On what basis do you make that determination? 

Two union officials responded “yes”; two responded “no”; and there was no response from one. 

Open inspector positions and difficulty covering vacations or other days off were offered as 

evidence of inadequate inspectors. 

What changes, if any, would you recommend in current FRA track inspection requirements? 

 FRA granted the Southeastern Pennsylvania Transportation Authority (SEPTA) a waiver 

regarding the twice-a-week inspection. This general chairman recommends removing the 

waiver. This would result in track being maintained to a higher standard. In addition, it 

would allow the inspectors to be responsible for two different sections of track, one 

inspected on Monday and Thursday and the other on Tuesday and Friday; they would 

develop familiarity with and “ownership” of that track, which would result in higher 

quality inspections. 

 Require a minimum of two people in the hi-railer used in the inspection. Because more 

repairs could be done than with a single person, there would be less speed restrictions. 

The second person, a helper, would learn the job as well as assist with repairs. 

 Give documentation to FRA, along with the inspection report, as to what the inspector 

did on a given day. 

 In inclement weather (heat/cold), put two inspectors together for safety. 

 Require two inspectors in hi-rail vehicle. 

 Standardize the training for inspectors. 

 Implement a maximum inspection speed for the hi-railer. 

 Implement a maximum inspection speed. 

 Put track inspectors under a track inspection supervisor who does not have other 

responsibilities. 

 Current supervisors have competing goals that cause the quality of inspections to suffer. 

This is primarily due to a lack of local forces for doing repairs. The problem has evolved 

over time. 
61

Are there any other aspects of the inspection process that you would like to comment on for 

FRA consideration in preparing its Report to Congress? 

 The people who do these inspections are knowledgeable. Given adequate time, they will 

do a quality job. 

 Inspectors are under more pressure to get inspections done in a timely fashion. If the 

inspector issues a speed restriction, the inspector will likely take "heat" from the 

supervisor, who in turn is getting pressure from above. The inspector is put on the 

defensive. The inspector must sign the inspection report, not the supervisor. If the 

inspector, against his better judgment, does not issue the speed restriction and there is a 

problem, the inspector is responsible. 

 The inspector’s job has gone from just doing inspection to inspection, plus remedial 

repairs, to one where the inspector is spending considerable time on non-inspection 

duties. If repair takes more than 30 minutes, repair should be done by repair force not the 

inspector. 

 The current process works. FRA should tighten up on compliance to make sure that the 

railroad makes the needed repairs and complies with time requirements for those repairs. 

 FRA should consider the results of the BMWED-distributed survey along with the results 

of these interviews of labor union officials in preparing its report. 
62

Appendix E. 

Results of Interviews with Roadmasters/Track Supervisors 

Number of Interviewees 12 

How long have you been a track supervisor? 

Range 12 to 35 years 

Mean 25.3 years 

Median 26.0 years 

Standard deviation 7.1 years 

Did you work as a track inspector prior to becoming a supervisor? If so, how long? 

Previous track inspection experience 5/12 

Range 0.3 to 15 years 

Mean 2.9 years 

Median 3.0 years 

Standard deviation 6.1 years 

How many track inspectors do you supervise? 

Range 1 to 6 track inspectors 

Mean 2.9 

Median 3.0 

Standard deviation 1.4 

On a typical day, how many hours do you work? 

Range 9 to 13 hours 

Mean 10.9 hours 

Median 10.5 hours 

Standard deviation 0.2 hours 
63

On a typical day, how many hours do you spend on inspection issues? 

Range 1 to 4 hours 

Mean 1.9 hours 

Median 2.0 hours 

Standard deviation 1.1 hours 

What types of training do your inspectors have that is specific to track inspection? 

On-the-job: 

More frequently than annually 10/12 

Annually 2/12 

FRA track standards: 

Annually 8/12 

Biennially 3/12 

Less than biennially 1/12 

FRA safety standards: 

Annually 10/12 

More frequently than annually 2/12 

Other training: 

Monthly ride along 4/12 

Track inspection training every other year 

or every 3 years 

2/12 

Operating rules, every other year 1/12 

Foreman refresher, every 3 years 1/12 

What additional training is necessary for track inspectors? 

None 6/12 

More field training 1/12 

Proper measurement training 1/12 
64

How do you assure the proficiency of your track inspectors? 

Review daily reports and conduct monthly ride along/co-inspection. 

What action do you take to improve a track inspector’s performance if it is unacceptable? 

If an inspector’s performance or skills are lacking or unacceptable, track supervisors will initially 

attempt to improve the inspector’s performance with individualized on-the-job training. If that 

proves insufficient, the supervisor may prescribe further formal training, possibly implement 

official disciplinary/citation actions, and finally, in extreme cases, resort to removing that 

inspector from service. 

How do you conduct job briefings with your inspectors? 

In-person 11/12 

Phone 7/12 

Other: email 1/12 

What topics are covered in the daily job briefings? 

Slow orders on territory 12/12 

Recent derailments 12/12 

Results of special inspections 12/12 

Results of track geometry inspections 12/12 

Spot maintenance 11/12 

Specialized equipment movement 11/12 

Recent accidents 11/12 

Mechanized maintenance 10/12 

Rough ride reports 9/12 

Other information included in job 

briefings* 

5/12 

* Other information included in job briefings: 

 Inspection standards 

 Recent injuries/safety concerns 

 Upcoming projects 

 Weather 

 Rider complaints 

 Previous shift’s work 
65

What criteria do you use to establish inspection territories? 

The following items were mentioned: 

 Track miles 

 Number of switches and yards 

 Million gross ton miles (MGT) 

 Type of terrain 

 Class of track 

On a typical day, how many miles of mainline track do your inspectors cover in total? (If an 

inspector inspects double track, multiply miles of track by 2; if triple track, multiply by 3, etc.) 

Range 25 to 110 miles 

Mean 58.9 miles 

Median 50.5 miles 

Standard deviation 24.5 miles 

What classes of main track do the territories of your inspectors include? 

Class 1 7/12 

Class 2 7/12 

Class 3 9/12 

Class 4 11/12 

Class 5 4/12 

Class 6 1/12 

Class 7 0/12 

Class 8 0/12 

Class 9 0/12 

Excepted Track 0/12 

Do you feel that you have an adequate number of inspectors on your division? 

Yes 10/12 

No 2/12 
66

How did you make that determination? 

Most of the respondents based their assessment on the fact that their inspectors are able to cover 

the required territory in the allocated time and that no overtime is regularly required to inspect 

their territory. 

Which of the following characterize the territories of your inspectors? 

Single track 11/12 

CWR 12/12 

Concrete ties 4/12 

Bridges 12/12 

Industry track 12/12 

Double track 10/12 

Desert terrain 2/12 

Urban area 8/12 

Highway crossings 11/12 

More than double track 3/12 

Mountainous terrain 3/12 

Tunnels 2/12 

Yard 12/12 

Other territory characteristics* 

* Other territory characteristics: 

 Curves 4/12 

 Rivers 4/12 

 Flash floods 1/12 

 Y-tracks 1/12 

What characteristics of your territory create challenges for the track inspection process? 

The most common responses were: 

 Curves cause gauge measurement problems and can present greater safety risks 

 Lack of track time due to high traffic 

 Inclement weather 
67

What territory characteristics trigger special inspections? 

Extreme heat 12/12 

Extreme cold 12/12 

Desert terrain 1/12 

Mountainous terrain 1/12 

Other* 

* Other: 

 Flash floods/excessive rain 12/12 

 Fires 1/12 

 Snow 1/12 

 High winds 3/12 

 Tornados 2/12 

 Accidents/collisions 1/12 

 Vandalism/trespassers 2/12 

How are inspectors assigned to a specific territory? 

Union bidding/seniority 8/12 

Company selection/appointment 4/12 

How often do you inspect with each of your track inspectors? 

Monthly 11/12 

Quarterly 1/12 

Does your railroad inspect more frequently than FRA regulations require? 

Yes 7/12 

No 5/12 

Examples are: 

 Double the FRA requirements 

 Yards are inspected once a week 

 Mainline track is inspected daily compared to FRA’s once a week requirement 

 Mainline inspection four times a week 

The two main reasons offered for greater inspection frequency are to maintain a higher level of 

safety and to avoid any operational downtime. Higher inspection frequencies are very common 

on key routes and routes that carry passengers or hazmat. 

Does your railroad inspect to FRA minimum safety standards or are your standards more 

stringent? 

Standards more stringent 7/12 

FRA minimum standards 3/12 

Unsure 2/12 
68

Examples are: 

 Class 1 track: Gauge tolerance is 573⁄4 inches vs. 58 inches for FRA 

 Maintain all track to Class 5 standards or higher 

What conditions would you not expect a track inspector working alone to fix? 

(Note: Many of the respondents stated that the track inspectors might repair any of the below 

defects; it depends on the extent and number of defects.) 

Tie plate issues 2/12 

Broken joint bars 3/12 

Missing fasteners 1/12 

Gage adjustment 9/12 

Missing bolts 0/12 

Spot surfacing 10/12 

Other conditions not fixed alone 6/12 

Under what circumstances would you assign a single inspector to a territory? What 

circumstances warrant a two-person inspection team? What benefits are there to a single 

inspector? Two inspectors working as a team? 

All, but one, of the interviewed railroads assign single inspectors for routine inspections. One 

railroad always has two inspectors per inspection team. They state that the reason for having one 

inspector is cost effectiveness and scheduling flexibility. However, the supervisors will assign 

more than one inspector to situations where safety is a concern–for example, inclement weather, 

dangerous localities, some special inspections, blind curves, and night patrols. Additionally, 

some of the supervisors responded that they assign two inspectors to yard and triple track 

inspections. 

How do your inspectors report the results of their work? 

Reporting is transitioning to electronic systems from paper-based systems. Verbal reports are 

frequently given on possible upcoming issues or “points of concern.” 

Always Mostly Sometimes Never 

Paper Reporting 3 1 2 6 

Electronic 10 0 1 1 

Other* 0 1 5 6 

*Other reporting methods include: 

 Verbally, either in-person or on the phone 

 Email 
69

How could the reporting process be improved? 

Works fine as is 5/12 

Communication between defect reporting 

systems and repair/maintenance tracking 

systems 

1/12 

Standardizing methods for location 

identification 

1/12 

What additional equipment would you provide to your inspectors if cost were not a 

consideration? 

Nothing else needed 3/12 

Handheld computer/PDA for data entry 2/12 

GPS for hi-rail 1/12 

Temperature indicator on rear-view mirror 1/12 

Mount laptop in hi-rail 1/12 

Electronic gauge monitor built into the 

truck to monitor the gauge as the hi-rail 

rolls over track 

2/12 

Larger crews / Separate repair crew 2/12 

Small hydraulic pump/circuit to drive 

hydraulic tools, especially have an impact 

wrench 

1/12 

Laser for checking surface alignment or 

digital self calibrating level board 

2/12 

How frequently do your inspectors work overtime to complete routine inspections? What 

causes the need for overtime? (e.g., waiting for track time, assignment to non-inspection duties, 

short-staffed) 

Five out of 12 respondents stated that their inspectors work overtime at least twice a week. 

Common causes include lack of track availability and inclement weather conditions. 

What types of automated inspections occur on your division? How frequently? 

Type of inspection (# using) Responses 

Ultrasonic rail flaw detection (12) There is considerable variation in frequency from 

once a month to twice a year. 

GRMS (9) Frequency varies from 4 times a year to once a 

year. All the respondents found GRMS to be very 

useful. 

TGMS (11) Respondents indicated that they use TGMS 

between 26 times a year to twice a year. They 

found TGMS to be very useful. 

VTI (8) Sporadic, based on when a vehicle equipped with 

VTI comes through their territory. All respondents 

found VTI to be useful. 
70

Are there any other inspections that you would find helpful? 

None 11/12 

A machine to check for “tight rail” 1/12 

Are there any aspects of the inspection process that you would like to comment on for FRA 

consideration in preparing its Report to Congress? 

 One respondent raised the concern that railroads are causing a “time bomb on ties” 

because they ignore bad ties if the rail surface quality is acceptable. This is leading to a 

potentially dangerous situation in which high-traffic rail is supported by decayed or 

damaged ties. 

 On certain railroads, the inspector who reports a fault is assigned the responsibility for 

repairing it or having it repaired. This potentially deters already overworked inspectors 

from reporting faults; the more faults they report, the more work they give themselves. 

 One respondent stated that remote track authority, instead of increasing inspector safety, 

is leading to potentially hazardous situations. Track inspectors may lose wireless service 

on their laptops and are unable to determine if they still have track authority in that 

section. Additionally, during track release, the computer is not responsive enough for 

them to obtain feedback with enough of a safety margin. There have been instances of 

the system releasing track when the inspector is still in the danger zone. 

 The supervisors also commented on inconsistency between FRA inspectors, i.e., different 

FRA inspectors interpret the same regulation differently. It would be beneficial if FRA 

defined the regulations or standards better, with the use of detailed pictures to supplement 

the word descriptions. 

 Similarly, FRA inspectors need to be a “Dr. of the railroad” and understand why and how 

the regulations and standards are defined. FRA inspectors should not respond to inquiries 

with, “That’s just the way it is.” 

 Certain respondents stated that they have no problems with FRA, and like openness and 

accessibility of FRA officials for discussion or help. However, other respondents stated 

that they find FRA to be very intimidating and that FRA officials do not treat them with 

dignity and respect. They stated that FRA can be very rude, especially the individuals 

higher in the hierarchy. It was also mentioned that people who leave railroads as 

disgruntled employees are hired at FRA. 

 One supervisor highlighted that finding the defect is only the first step. Inspection is just 

part of the process. Repair is the other part, and they need resources to correct the 

problem. It is easier to find the places that need repair than it is having the resources to 

do the repair. 

 A respondent stated that the track safety rules do not allow a lone worker to go into a 

control point, which hinders the inspection process. He believes that is safe; they were 

able to do it safely before RWP and should be allowed to do it now. 

 One supervisor believes that older smaller rail (90 lbs) should be upgraded to the standard 

6-inch base and 119+ lb weights. The smaller rail is old and brittle. 
71

 One respondent commented on the significant move towards a more automated 

inspection process; it should not replace on-foot inspection, especially in areas with 

passenger trains. In his view, any attempt to replace visual or on-foot inspection with 

automated inspection is not acceptable. Automated inspection is a supplemental tool and 

should not reduce or replace visual or on-foot inspection. 
72

Appendix F. 

Results of Interviews with Division Engineers 

Number of Interviewees 5 

How long have you been a division engineer? 

Range 10 months to 12.5 years 

Median 3.5 years 

How many years of experience do you have doing track inspection or supervision? 

Range 20 to 35 years 

Median 24.0 years 

How large is your division (track miles)? 

Range 746 to 2356 track miles 

Median 1500.0 track miles 

How many territories (subdivisions) are in your division? 

Range 5 to 14 subdivisions 

Median 7.0 subdivisions 

How many track supervisors/roadmasters report to you? 

Range 5 to 14 track supervisors / roadmasters 

(Note: Four out of the five division engineers reported that they supervise either five or six track 

supervisors; the remaining division engineer reported that he supervises 14 track supervisors.) 

What characteristics of your division create challenges for the track inspection process? 

The following were mentioned: 

 Heat, rivers, soil compaction 

 Weather, high winds, floods 

 Roadway Worker Protection (RWP) rules, curves, tunnels, volume/density of traffic, foul 

time (dispatcher workload) 

 Roadbed, yards and abutting industries 

What territory characteristics trigger special inspections? 

Extreme heat 5/5 

Extreme cold 4/5 

Desert terrain 0/6 

Mountain terrain 1/6 

Other* 3/6 
73

*Other items mentioned: 

 Severe weather 

 Storms, bridge strikes, rough ride reports, ARMS hits, train partings, tunnels, corroded 

rail 

 Flooding 

What criteria do you use to establish inspection territories? 

 Number of trains versus miles, and number of switches and curves. 

 Mileage and type of track (CWR vs. jointed rail) and class of track 

 # of mainline tracks, yards, sidings, class of track 

 Roadbed, yards and abutting industries 

 Track miles/tonnage 

What is the average size of an inspector’s territory in your division? 

Miles of mainline track: 

Range 10 to 110 miles 

Median 83.0 miles 

Number of yard sites: 

Range 3 to 26 sites 

How do you determine how many inspectors you need on a territory? 

 Curves, turnouts, miles of track 

 Mileage 

 # of mainline tracks, yards, sidings, class of track 

 Total number of main and industry tracks along with number of yard tracks 

 Determined by chief engineer 

Do you feel that you have an adequate number of inspectors on your division? 

Yes 5/5 

No 0/5 

How did you make that determination? 

 Watching inspections ensuring they have adequate time to inspect assets. 

 Experience 

 Average total miles and yard tracks 

Note: The methodology for determining the number of inspectors and whether or not the current 

number is adequate is not an exact science. These decisions seem to be based on experience. 

Do you conduct a morning call with your track supervisors/roadmasters? 

Only one division engineer (DE) reported conducting a daily morning call. Topics for his calls 

include RWP, previous night’s work, work to be scheduled for inspectors and revisions to 

standards or engineering practice. The other four DEs reported having a weekly call with 

roadmasters. Topics for weekly conference calls include: discussion of incidents at the local, 

regional and system level; proactive activities related to personal safety, derailment prevention 
74

and public safety issues; and identification of trends related to inspection compliance 

requirements. One DE reported a nightly report from roadmasters on activities including daily 

and weekly plans, service interruptions, etc. 

What types of training does your railroad provide for track inspection personnel? 

On-the-job: 

More frequently than annually 5/5 

FRA track standards training: 

Less than biennially 3/5 

Biennially 1/5 

Annually 1/5 

FRA safety standards training: 

Biennially 2/5 

Annually 2/5 

More frequently than annually 1/5 

Other track inspection related training: 

 Heat and cold inspections, track stability (twice annually) 

 Field visits by staff to discuss revisions, standards, new practices or policies, derailment 

findings 

 Annual additional geometry-related training 

How frequently do your inspectors work overtime? 

One person responded “often.” Other responses were “hardly ever” to “occasionally.” Reasons 

for overtime were: weather, mostly track and time or dispatcher related issues, assignment to 

non-inspection duties, short-staffed, and covering vacations, holidays and absenteeism. 
75

What types of automated inspections occur on your division? How frequently? In what way 

are they useful? 

Type of inspection (# using) Frequency (# responding) 

Ultrasonic rail flaw detection (5/5)  30 to 90 days depending on territory (1/5) 

 Core route 12 times per year; more in winter 

than summer (1/5) 

 Two times per year (1/5) 

 Every 45 days; also test high-volume yard 

track (1/5) 

 Eight times per year (1/5) 

GRMS (4/5)  Annually (3/5) 

 Subdivision specific; used in areas of marginal 

tie condition (1/5) 

TGMS (5/5)  Four times per year (2/5) 

 Twice per month (1/5) 

 Biannually; good experience for new 

inspectors (1/5) 

 Three times per year (1/5) 

VTI (4/5)  Monthly (2/5) 

 Impact detectors (wayside) only (1/5) 

 ARMS (Automated Remote Monitoring 

System) – 16 units daily 

Other types of inspection: 

 Rail wear (same vehicle as gage restraint) 

 FRA track geometry car – 2 times/year 

Does your railroad inspect more frequently than FRA regulations require? 

Yes 5/5 

No 0/5 

Examples are: 

 On heavy tonnage lines we inspect every day 

 On gas welded rail and in adverse weather 

 On routes with passenger service 

 Special inspections (extreme heat, cold, etc.) 

 Monitor wear for compliance with rail change out standards 

The only reason offered for more frequent inspection was, “For safety reasons; look for broken 

rail and joint issues.” 

Does your railroad inspect to FRA minimum safety standards or are your standards more 

stringent? 

Three reported having more stringent standards. Examples were: 

 Gage and surface defect tolerances tighter by 1/8" 

 Rail changeout standards 
76

Reasons for the more stringent standards: 

 Safety 

 Make repairs before they become defects 

Are there any other inspections that you would find helpful? 

 Working on ground penetrating radar for fouled ballast and tie support; need joint bar 

testing for jointed rail 

 VERSE (rail uplift) testing (for CWR) 

What changes, if any, would you recommend in current FRA track inspection requirements? 

 Need better definitions, e.g. monthly versus 30 days needs changing. More use of handheld recording devices; electronic instead of paper. 

 Rewrite tie defect definition to make it clearer. 

Are there any other aspects of the inspection process that you would like to comment on for 

FRA consideration in preparing its Report to Congress? 

There were no further comments. 
77

Appendix G. 

Results of Interviews with System Level Officers 

Number of interviewees 6 

How long have you been in your current position at your railroad? 

Range 1 to 8 years 

Mean 4.2 years 

Median 4.0 years 

Standard deviation 2.3 years 

How many years of experience do you have doing track inspection or supervision? 

Range 15 to 35 years 

Mean 27.0 years 

Median 28.0 years 

Standard deviation 6.8 years 

How many miles of track does your railroad have? 

Range 1943 to 39,700 miles 

Mean 23,866.3 miles 

Median 26,500.0 miles 

Standard deviation 15,031.8 miles 

How many track inspection personnel, both inspectors and supervisors, do you currently 

employ? 

Range 74 to 881 inspection personnel 

Mean 358.8 

Median 294.0 

Standard deviation 301.4 

How do you determine if your number of inspection personnel is adequate? 

The number is based upon the railroad’s previous experience and the ability of the inspectors to 

complete their territory in the allocated time. 

What is the typical size of a track inspector’s territory on your railroad? 

The responses to this question were not included in this summary because the system level 

officers oversee large areas that encompass many divisions and large numbers of inspectors, and 

the system level officer’s response to this question would not provide a specific response to this 

question. 

What types of training does your railroad provide for track inspection personnel? 

On-the-job: 

More frequently than annually 6/6 
78

FRA track standards: 

More frequently than annually 1/6 

Annually 3/6 

Biennially 2/6 

FRA safety standards: 

More frequently than annually 2/6 

Annually 4/6 

Other training: 

CWR training – annually 1/6 

Track buckle and washout classes – 

annually 

1/6 

Inclement weather training – annually 1/6 

REDI Center 1/6 

How do you determine whether inspection should be on foot or via hi-rail? 

 Traffic density 

 Compliance with FRA standards 

 Track accessibility 

Does your railroad have a recommended speed for hi-rail inspections? 

Yes 2/6 

No 4/6 

Do you have a maximum speed for inspections? 

Yes 3/6 

No 2/6 

Unsure 1/6 

How did you establish these speeds? 

 Experience 

 To fit conditions and inspection requirements 

 FRA recommendations 

 Type of track and track characteristics 

Does your railroad inspect more frequently than FRA regulations require? 

Yes 6/6 

No 0/6 

Examples are: 

 Inspect at twice the FRA required frequency on key routes. 

 Three visual inspections per week if over 10 MGT/year. 
79

Does your railroad inspect to FRA minimum safety standards or are your standards more 

stringent? 

Standards are more stringent 3/6 

Some standards are more stringent 2/6 

No response 1/6 

Examples are: 

 Replace flawed rail earlier than required by FRA standards. 

 Perform a walking inspection of each critical yard track at least two times per month with 

at least 10 days between inspections. 

What types of automated inspections occur on your railroad? How frequently? In what way 

are they useful? 

Type of inspection (# using) Responses 

Ultrasonic rail flaw detection (6/6) 

The reported frequencies vary depending on the 

type of track, its tonnage and railroad. Generally 

varies between twice a month to once a year. 

Recent improvements in ultrasonic testing 

technology to help find defects masked by shells 

or spalls have proven very beneficial. 

GRMS (4/6) At least once a year. 

TGMS (6/6) 

Respondents indicated that they use TGMS 

between once a year to twice weekly. The most 

common response was four times a year. 

VTI (5/6) Dependent on locomotive schedules. 

Other types of inspection: 

 Optical joint bar inspection vehicle, some specified Herzog or digital imaging 

 Aurora laser system to locate and prioritize areas of concrete tie rail seat abrasion. 

Are there any other inspections that you would find helpful? 

 More accurate methods to locate cracks in joint bars. 

 Rail seat abrasion measurements need improvement – currently the Aurora system has 

70-percent accuracy. 

What changes, if any, would you recommend in current FRA track inspection requirements? 

 213.53 Gage: Would like to see allowable tight gage differ up to three-quarters of an 

inch from standard gage. 

 213.137 Frogs: Would like to see part (d) eliminated or modified to allow for use of 

flange-bearing frogs in all classes of track without a waiver. 

 213.143 Frog guard rails and guard faces; gage: Would like to see this eliminated and 

replaced with “width of opening from guard face of guard rail to gage face of running rail 

must not exceed 17⁄8 inches.” 

 Northeast Corridor should go to weekly inspection versus twice weekly because of the 

additional inspections done by geometry cars. 
80

 CWR regulations need modification to allow railroads to use their own experience. 

Additionally, eliminate requesting FRA approval to change CWR policy if more stringent 

than FRA standards. Note: This comment was mentioned by two respondents. 

 Include yard rail testing which FRA doesn’t currently cover. 

 Fewer requirements. 

 Different standards for metro areas. 

Are there any other aspects of the inspection process that you would like to comment on for 

FRA consideration in preparing its report to Congress? 

 Do not change anything that keeps railroads from capitalizing track. 
81 

Appendix H. 

Ideal Observer for Visual Track Inspection 

H.1 Theory of the Ideal Observer 

One way to determine the maximum speed at which a visual track inspection can occur is to 

construct a theory of the ideal observer. The ideal observer provides an upper limit on how well 

the best possible observer can perform by making optimal use of the information available from 

the stimulus (Wickens 2002). In the present case, the maximum speed will depend critically 

upon human visual and cognitive capabilities and limitations. To the extent that all relevant 

human capabilities and limitations are known and are accurately captured, the ideal observer 

provides a benchmark against which actual performance and practices can be compared. In the 

present case, the ideal observer can serve as a comparison to practices reported in surveys, 

interviews and focus groups regarding the speed at which visual inspections are routinely 

performed. Maximum speed in miles per hour (mph) can be defined as 

mph  r / t (1) 

where r is the distance from the observer to the object to be detected and t is the exposure time, 

which is the amount of time required by the observer to detect the object with some degree of 

accuracy. 
82 

H.2 Human Factors Considerations 

There are several aspects to this from a Human Factors point of view that must be considered: 

 1. Visual acuity and detection accuracy 

 2. Visual search time 

 3. Attention (vigilance, distraction, fatigue) 

H.2.1 Visual Acuity 

Visual acuity is the limit in the ability to resolve detail (Boyce 1997, p. 872). Visual acuity is 

generally specified in terms of the visual angle (θ) between the observer’s eye and the largest 

dimension (l) of the object being viewed. 

Figure 21. Diagram of observer, object, and relevant parameters 

If θ is small, then 

r

57.3l   (2) 

in degrees (Graham 1951, p. 872), where r is again the distance of the object from the observer. 

Visual acuity (θ) is a function of light intensity and exposure time (Riggs 1972, p. 300). 

Light Intensity. If we assume that track inspections take place during daytime and under 

good visibility conditions, visual acuity is at a plateau of approximately 0.5 minutes of arc 

(Bartley 1951, p. 958). This, however, is a threshold value (50-percent detection). Visual acuity 

in the psychophysics literature is generally expressed as the smallest visual angle at which 

detection can occur with 50-percent accuracy. Detection accuracy is best thought of as a 

probability: accuracy can approach zero and 100 percent, but never reaches either limit. A 

detection accuracy of 50-percent (probability = 0.5) is considered the detection threshold in 

classical psychophysics. Intuitively, a much higher detection accuracy for safety critical tasks, 

such as track inspection, would be desired. A rule of thumb suggested by Boyce (1997, p. 873) 

is that the visual angle needs to be four times bigger than the threshold for quick resolution 

without affecting visual performance. However, a fourfold increase in the visual angle from the 

threshold only results in 59.5-percent correct detection (see Appendix H.3 to this report, or Egan 

1975, p. 81 for computational details and definitions of signal-to-noise ratio S/N and d’Y/N). A 

value above 90 percent would seem better-suited for a safety-critical task. Table 1 shows the 

visual angles for 50-, 59.5-, 90-, 95-, and 99-percent correct detection. 
83 

Table 1. Visual Angle, S/N, d’ and Percent Correct Detection. 

Percent Correct 

Detection d’Y/N S/N Visual Angle, θ (min arc) 

50 0.085 1.0 0.5 

59.5 0.34 4.0 2.0 

90 1.82 21.4 10.71 

95 2.33 27.45 13.73 

99 3.29 38.77 19.38 

Exposure Time. The Bunsen-Roscoe Law of photochemistry is obeyed if the eye is exposed to 

light for short periods of time, such that the amount of energy (E) needed to detect an object is 

constant and E is the product of time (t) and luminance (L). This law does not apply above a 

critical duration, tc. Above tc luminance alone determines acuity. Values of tc range from 0.01 to 

over 0.2 seconds. So, to set exposure time, according to Riggs (1972, p. 304): 

The duration of the best ‘look’ must be greater than tc, but it need not be 

longer than one or two tenths of second at daylight levels of luminance. 

Accordingly, we set minimum exposure time (t) at 0.2 seconds. 

It is now possible to specify the maximum speed at which objects of various sizes can be 

detected with a particular degree of accuracy by combining equations (1) and (2): 

t

l mph 57.3  (3) 

This is shown in Figure 22 for 50-, 59.9-, 90-, 95-, and 99-percent correct detection rates. 

Figure 22. Relationship between maximum inspection speed, defect size and detection accuracy 

1

10

100

1000

10000

100000

1000000

10000000

0.001 0.01 0.1 1 10 100

Defect Size (ft)

Speed (MPH)

50%

59.50

90%

95%

99%
84 

The size of the smallest object that must be detected would set the limit on track inspection speed 

considering only visual acuity and desired detection accuracy. The smallest object in 

Figure 1 is 0.1 inches and can be detected with a 99-percent detection rate at 5 mph. The same 

object would be detected 90 percent of the time at approximately 9 mph. At threshold, the object 

would be detected 50 percent of the time at a speed of 195 mph–not a practical speed or track 

inspection approach, of course. 

H.2.2 Visual Search 

Visual search time has been extensively studied and an excellent summary of that work can be 

found in Luce (1986, p. 428). The average time required to search for an item is given by 

0 S  kM  r (4) 

where k is the mean time per item, M is the number of items, and r0 is the residual time. The 

values of k and r0 are 40 milliseconds (msec) and 400 msec, respectively. The search time would 

include the exposure time in order to estimate total time available to traverse the distance to the 

object. In a case where there is only one object to be found in an otherwise blank field (an 

unrealistic scenario, but one which sets a lower boundary), the search and exposure time would 

be 440 msec. If we substitute S in equation (4) for t in equation (3), the maximum speed for 

track inspections is now 

S

l mph 57.3  (5) 

Figure 23 shows this relationship for 90-percent accuracy, Figure 24 shows the relationship for 

95-percent accuracy, and Figure 25 shows the relationship for 99-percent accuracy. 

Figure 23. Relationship between maximum inspection speed, defect size, and number of search objects for 

90-percent detection accuracy 

90% Detection Accuracy

0.1

1

10

100

1000

10000

100000

0.00 0.01 0.10 1.00 10.00 100.00

Defect Size (ft)

Speed (mph)

1

4

16

64

256
85 

Figure 24. Relationship between maximum inspection speed, defect size, and number of search objects for 

95-percent detection accuracy 

Figure 25. Relationship between maximum inspection speed, defect size, and number of search objects for 

99-percent detection accuracy 

It is easy to see that as the number of search objects increases, the time to search increases; so, 

the speed of the inspection must decrease. Again, using the smallest object (0.1 inch) as the 

example, maximum speed with 90-percent accuracy is approximately 4, 3, 1.75, 0.6, and 0.2 

mph; with 1, 4, 16, 64, and 256 objects to search. At 95-percent accuracy, maximum speed is 

95% Detection Accuracy

0.1

1

10

100

1000

10000

100000

0.00 0.01 0.10 1.00 10.00 100.00

Defect Size (ft)

Speed (mph)

1

4

16

64

256

99% Detection Accuracy

0.01

0.1

1

10

100

1000

10000

100000

0.00 0.01 0.10 1.00 10.00 100.00

Defect Size (ft)

Speed (mph)

1

4

16

64

256
86 

approximately 3, 2.5, 1.4, 0.5, and 0.13 mph; with 1, 4, 16, 64, and 256 objects to search. At 

99-percent accuracy, maximum speed is approximately 2.3, 1.8, 1, 0.3, and 0.1 mph; with 1, 4, 

16, 64, and 256 objects to search. 

H.2.3 Attention 

Attention, including vigilance, distraction, and fatigue, is a complex issue to model in a task like 

track inspection. It should be noted that this is a broad subject with many components that may 

require separate consideration. For example, if one is fatigued, it may be easier to be distracted 

and harder to maintain vigilance. However, for purposes of this discussion, we will simplify and 

consider a track inspection task to be primarily a vigilance task. This is consistent with the need 

to search for defects among multiple distracters (search objects) while visual information is 

flowing by at the speed of inspection. 

The original studies on vigilance were performed by Mackworth (1950), and subsequent studies 

have found the basic phenomenon to be robust. According to Boff and Lincoln (1988, Vol II, 

p. 1504): 

The correct detection of signals (hit rate) in most simple vigilance tasks 

shows a decrement over time. When hit rate is averaged for blocks of 

time (e.g., 30 min) in a 2-hr task, the vigilance decrement is greatest 

between the first and second blocks. 

According to Luce (1986, p. 176), at low signal rates correct detections in the Mackworth 

vigilance experiments fell from 85 percent in the first half hour to 73 percent in the rest of the 

watch. This corresponds to a change in d’Y/N from 1.47 to 0.86 or 0.61 units. 

Thus, to maintain performance at a desired level of percent correct detection it would be 

necessary to increase the visual angle sufficiently to compensate for this amount of vigilance 

decline after the first half hour. 

Figure 26, Figure 27, and Figure 28 show the relationship between maximum inspection speed, 

defect size and number of search objects for vigilance decrement adjusted detection accuracy. 
87 

Figure 26. Relationship between visual inspection speed, defect size, and number of search objects for 

vigilance-adjusted, 90-percent correct detection accuracy 

Figure 27. Relationship between visual inspection speed, defect size, and number of search objects for 

vigilance-adjusted, 95-percent correct detection accuracy 

Vigilance Adjusted 90% Detection Accuracy

0.1

1

10

100

1000

10000

100000

0.00 0.01 0.10 1.00 10.00 100.00

Defect Size (ft)

Speed (mph)

1

4

16

64

256

Vigilance Adjusted 95% Detection Accuracy

0.1

1

10

100

1000

10000

100000

0.00 0.01 0.10 1.00 10.00 100.00

Defect Size (ft)

Speed (mph)

1

4

16

64

256
88 

Figure 28. Relationship between visual inspection speed, defect size, and number of search objects for 

vigilance-adjusted, 99-percent correct detection accuracy 

Vigilance Adjusted 99% Correct Detection

0.01

0.1

1

10

100

1000

10000

100000

0.00 0.01 0.10 1.00 10.00 100.00

Defect Size (ft)

Speed (mph)

1

4

16

64

256
89 

H.3 ADDENDUM: Visual Angle (θ) and Probability of Correct Detection 

Green and Swets (1966, p. 190) provides the basis for the Boyce (1997) rule of thumb, and 

conveniently, Green and Swets’ Signal Detection Theory (SDT) provides a means of relating the 

probability of a correct decision to the S/N, and ability to detect (sensitivity or d’). For this 

discussion we assume that signal-plus-noise and noise distributions are normally distributed. 

In a normal distribution probabilities are often expressed as z-transformed scores, where 

dt x t

z

z





















  



 



     

 2

2

exp (2 )

1 ( ) 1 / 2

 

 (A1) 

We know that the threshold value of θ is 0.5 min of arc, which means that the probability of a 

correct decision is 0.5. This corresponds to a z-score of 0. Because equation (A1) is difficult to 

evaluate, extensive tables exist to relate probabilities and z-scores. 

To relate θ to the probability of a correct decision, it is necessary to discuss two different 

observation paradigms and how they relate to S/N. By definition, at threshold, S/N =1. 

Empirically, however, the relationship between d’ and S/N depends on the particulars of the 

observation paradigm and local conditions. 

In a simple Yes/No paradigm (Y/N), observers are presented with a single observation interval 

and are asked to respond “yes” if a stimulus is present or “no” if a stimulus is not present (nostimulus). It is known that observers will be biased to say “yes” if the probability of a stimulus 

interval is greater than a no-stimulus interval, and vice-versa. However, even if the probability 

of stimulus and no-stimulus intervals are the same, the observer’s perceived probability of 

stimulus and no-stimulus intervals may not be equal, and bias may still result. The consequence 

of this is that d’Y/N, the measure of sensitivity in Y/N, can have considerable response bias 

associated with it. In general, sensitivity is defined as 

d ' z(Hit)  z(FA) (A2) 

If there is no bias in the observation paradigm, 

z(Hit)  z(FA) (A3) 

In Y/N, d’Y/N = z(Hit) – z(FA), and it is assumed that z(Hit) ≠ z(FA). 

In a 2 Interval Forced Choice (2IFC) observation paradigm, observers are presented with two 

observation intervals, one of which contains the stimulus. The order of the stimulus and nostimulus intervals is random, and the observer must identify the interval that contained the 

stimulus. This is clearly an artificial situation, but it is very useful because it does not produce 

response bias. In 2IFC, the measure of sensitivity is d’2IFC . The 2IFC paradigm is unbiased, so 

that 

 ) ' ( ) ( d 2IFC  z Hit  z FA (A4) 

and z(Hit) = z(FA). Because there are two observation intervals in 2IFC, the relationship 

between sensitivity in Y/N and 2IFC is 

d IFC d Y / N

0.5

2

'  2 ' (A5) 
90 

This allows the artificial observation paradigm of 2IFC to be directly compared with or 

translated into the more natural observation paradigm of Y/N. Moreover, in 2IFC, the 

probability of a correct decision (A) is 

A  p(Hit)  p(FA) (A6) 

Consequently, if one wishes to set the sensitivity of the Y/N paradigm in terms of the probability 

of a correct decision, one could easily use a table of the normal distribution to determine the 

value of z(Hit) associated with A and double z(Hit) to obtain d’2IFC. Equation (A5) would then 

be used to determine d’Y/N. 

Empirically, Green and Swets (1966, p. 190) found that 

N

S d'

Y / N  0.085 (A7) 

At threshold, by definition S/N = 1, so d’Y/N = 0.085. 

In the case of visual acuity, this means that when θ = 0.5 min, d’Y/N ≈ 0.085, A ≈ 0.5 or 50 

percent. 

For the Boyce (1997) rule of thumb, a fourfold increase from threshold gives θ = 2 min. 

From (A7), d’Y/N = 0.085 x (2/0.5) = 0.34 

From (A5), d’2IFC = 0.34 x 1.414 = 0.48 

From (A4), z(Hit) = 0.5 x d’2IFC = 0.24 

From tables of the normal distribution, A = 0.599 or 59.9 percent 

As an example, if we want the value of θ that has a 90 percent correct detection: 

From tables of the normal distribution, if A = 0.9 or 90 percent, then z(Hit) = 1.29, 

From (A4), d’2IFC = 2 x z(Hit) = 2.58 

From (A5), d’Y/N = d’2IFC/1.414 = 1.82 

From (A7), S/N = d’Y/N/0.085 = 21.4 

Therefore, θ = 21.4 x 0.5 = 10.7 min 

As a further example, if we want the value of θ that has a 99 percent correct detection: 

From tables of the normal distribution, if A = 0.99 or 99 percent, then z(Hit) = 2.33, 

From (A4), d’2IFC = 2 x z(Hit) = 4.66 

From (A5), d’Y/N = d’2IFC/1.414 = 3.29 

From (A7), S/N = d’Y/N/0.085 = 38.77 

Therefore, θ = 21.4 x 0.5 = 19.38 min 
91 

Appendix I. 

RSAC Recommended Definition of “Qualified Operator” in 49 CFR 

§ 213.238 

§ 213. 238 Qualified operator 

Each provider of rail flaw detection shall have a documented training program in place 

and shall identify the types of rail flaw detection equipment on which each operator has 

received training and is qualified. 

(a) A qualified operator shall be trained and shall have written authorization by the 

employer to: 

(1) Conduct a valid search for internal rail defects utilizing specific type(s) of 

equipment they are authorized and qualified to operate; 

(2) Determine that such equipment is performing as intended; 

(3) Interpret equipment responses and institute appropriate action in accordance 

with the employer’s procedures and instructions; 

(4) Determine that each valid search for an internal rail defect is continuous 

throughout the area inspected and has not been compromised due to 

environmental contamination, rail conditions, or equipment malfunction. 

(b) The operator must have received training in accordance with the internal documented 

training process and complete a minimum of 160 hours rail flaw detection experience 

under direct supervision of a qualified operator or rail flaw detection equipment 

manufacturer representative. The operator must demonstrate proficiency in the rail defect 

detection process, including equipment to be used, prior to initial qualification and 

authorization by the employer on each type of equipment. 

(c) Re‐evaluation and any necessary recurrent training shall be determined in accordance 

to a documented internal policy. The re‐evaluation and recurrent training can consist of a 

periodic review of test data submitted by the operator as determined by an internal audit 

process. The re‐evaluation process shall require that the employee successfully complete 

a recorded examination and demonstrate proficiency to the employer on the specific 

equipment type(s) to be operated. 

(d) Each employer of an authorized qualified individual shall maintain written or 

electronic records of each qualification in effect. Each record shall include the name of 

the employee, the equipment to which the qualification applies, and the date of 

qualification and date of most recent successful re‐evaluation. 

(e) Employees that have demonstrated proficiency in the operation of rail flaw detection 

equipment prior to the date of promulgation shall be grandfathered into the program and 
92 

considered a qualified operator, regardless of the previous training program they were qualified 

under.1

 Such grandfathered operators shall be subject to paragraph (c). 

(f) Qualification records, as well as a copy of equipment‐specific training programs and 

materials, recorded examinations, demonstrated proficiency records, and authorization 

records, shall be kept at a location designated by the employer; and available for 

inspection and copying by the Federal Railroad Administration during regular business 

hours. 

 

1

 This rule has not yet been published. 
93 

References 

Bartley, S. H. (1951). “The psychophysiology of vision.” In S. S. Stevens (Ed.), Handbook of 

experimental psychology (pp. 921-984). New York: Wiley. 

Boff, K. R., and Lincoln, J. E. (Eds.). (1988). Engineering data compendium. Human 

perception and performance. Wright-Patterson Air Force Base, Ohio: Harry G. 

Armstrong Aerospace Medical Research Laboratory. 

Boyce, P. R. (1997). “Illumination.” In G. Salvendy (Ed.), Handbook of human factors and 

ergonomics (pp. 858-890). New York: Wiley. 

Egan, J. P. (1975). Signal detection theory and ROC analysis. New York: Academic. 

Gertler, J., and Viale, A. Work Schedules and Sleep Patterns of Railroad Maintenance of Way 

Workers. (DOT/FRA/ORD-06/25). Washington, DC: Federal Railroad Administration. 

Graham, C. H. (1951). Visual perception. In S. S. Stevens (Ed.), Handbook of experimental 

psychology (pp. 868-920). New York: Wiley. 

Green, D. M., and Swets, J. A. (1966). Signal detection theory and psychophysics. New York: 

Wiley. 

Keeping, E.S. (1995). Introduction to Statistical Inference. New York: Dover Publications. 

Levy, P., and Lemeshow, S. (1999). Sampling of populations: Methods and applications. 

New York: John Wiley & Sons, Inc. 

Luce, R. D. (1986). Response times. Oxford: Oxford Press. 

Mackworth, N. H. (1950). Researches on the measurement of human performance (Report No. 

268). London: Medical Research Council. 

Riggs, L. A. (1972). “Vision.” In J. W. Kling & L. A. Riggs (Eds.), Woodworth & Sclosberg’s 

experimental psychology (pp. 273-314). New York: Holt, Rinehart and Winston. 

Ross, S. (2006). A First Course in Probability. New Jersey: Pearson Prentice Hall. 

Swets, J.A., and Pickett, R.M. (1982). Evaluation of diagnostic systems: Methods from signal 

detection theory. New York: Academic Press. 

Wickens, T. D. (2004). Elementary signal detection theory. New York: Oxford Press.