A STUDY ON THE WHEEL-RAIL INTERACTION AT SWITCH POINTS TO REDUCE DERAILMENTS IN TURNOUTS. Samet Ozturk

Transcription

1 A STUDY ON THE WHEEL-RAIL INTERACTION AT SWITCH POINTS TO REDUCE DERAILMENTS IN TURNOUTS by Samet Ozturk A thesis submitted to the Faculty of the University of Delaware in partial fulfillment of the requirements for the degree of Master of Civil Engineering Spring 2014 Copyright 2014 Samet Ozturk All Rights Reserved

2 UMI Number: All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. UMI Published by ProQuest LLC (2014). Copyright in the Dissertation held by the Author. Microform Edition ProQuest LLC. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, MI

3 A STUDY ON THE WHEEL-RAIL INTERACTION AT SWITCH POINTS TO REDUCE DERAILMENTS IN TURNOUTS by Samet Ozturk Approved: Allan M. Zarembski, Ph.D. Professor in charge of thesis on behalf of the Advisory Committee Approved: Harry W. Shenton III, Ph.D. Chair of the Department of Civil and Environmental Engineering Approved: Babatunde Ogunnaike, Ph.D. Dean of the College of Engineering Approved: James G. Richards, Ph.D. Vice Provost for Graduate and Professional Education

4 ACKNOWLEDGMENTS I thank and praise God for giving me this opportunity and guiding me throughout my Master's education period. I would like to express my sincere gratitude to Dr. Allan Zarembski for his kind guidance, excellent interaction, and support in this research. I want to thank many people who gave me great help and suggestions. Especially, I would like to thank my former adviser Dr. Thomas Schumacher for his excellent technical advice and assistance in any aspects. I would also like to thank Chris Reoli for her unlimited help. I would like to thank the Turkish Government - Turkish Ministry of National Educationfor financial support and all the members of Turkish Attache in the US for their encouragement. Finally, I am indebted to my parents and brother for their endless love and boundless mental support and all the members of my family for their encouragement. iii

5 TABLE OF CONTENTS LIST OF TABLES... vii LIST OF FIGURES... viii ABSTRACT... xii Chapter 1 INTRODUCTION Statement of the Problem... 1 Objectives of the Study... 3 Overview of Turnouts and Definitions of Terms Organization of the Thesis... 7 LITERATURE REVIEW Research on Wheel Climb Derailments Nadal's single wheel L/V limit criterion... 8 Worn Rail L/V ratio Weinstock's Axle-Sum L/V limit criterion Japanese National Railways' L/V time duration criterion General Motors Electromotive Division's L/V time criterion Association of American Railroads Wheel Climb Duration Limit Federal Railroad Administration Wheel Climb Distance Limit TTCI Wheel Climb Distance Criterion Research on Reducing Derailments at Turnouts in US Railroads Railroad Track... 4 Wheels and Wheel Flange... 4 Overview and Components of Turnouts... 4 Network rail standards Swiss rail standards WHEEL CLIMB FAILURE MECHANISMS AT SWITCH POINT iv

6 4 METHODOLOGY AND RESULTS Moderately Worn Wheel Overlays Good switch point - turnout Damaged switch point - turnout Yard switch point - turnout Worn switch - turnout sample Worn switch - turnout sample New Wheel Overlays Good switch point - turnout Damaged switch point - turnout Yard switch point - turnout Worn switch - turnout sample Worn switch - turnout sample SWITCH POINT INSPECTION TOOLS IDEA Field Analysis Results and Discussions IDEA Field Analysis Results and Discussions IDEA Field Analysis Results and Discussions CONCLUSIONS Conclusions from Chapter 4 and Chapter Statement of Problems Left Unsolved REFERENCES Appendix A WHEEL PROFILE COORDINATES A.1 Moderately worn wheel profile coordinates A.2 New wheel profile coordinates v

7 B SWITCH POINT COORDINATES B.1 Good switch point - turnout coordinates B.2 Damaged switch point - turnout coordinates B.3 Yard switch point - turnout coordinates B.4 Worn switch point - turnout sample 1 coordinates B.5 Worn switch point - turnout sample 2 coordinates vi

8 LIST OF TABLES Table 1.1: Number of derailments at turnouts based on causes... 2 Table 4.1: Table 4.2: Summary of the good switch point-turnout - moderately worn wheel interaction Summary of the damaged switch point-turnout - moderately worn wheel interaction Table 4.3: Summary of the yard switch point-turnout - moderately worn wheel interaction.. 41 Table 4.4: Table 4.5: Summary of the worn switch point sample 1 turnout - moderately worn wheel interaction Summary of the worn switch point sample 2 turnout - moderately worn wheel interaction Table 4.6: Summary of the good switch point-turnout - new wheel interaction Table 4.7: Summary of the damaged switch point-turnout - new wheel interaction Table 4.8: Summary of the yard switch point-turnout - new wheel interaction Table 4.9: Summary of the worn switch point-turnout sample 1- new wheel interaction Table 4.10: Summary of the worn switch point-turnout sample 2 - new wheel interaction vii

9 LIST OF FIGURES Figure 1.1: Number of derailments at turnouts based on causes... 2 Figure 1.2: Wheel - Rail Interaction (from ref.[5])... 4 Figure 1.3: Turnouts and components (from ref. [4])... 5 Figure 1.4: Turnout size sample No. 3 Turnout (from ref. [27])... 6 Figure 2.1: Wheel flange contact diagram (from reference [22])... 9 Figure 2.2: Forces diagram on worn rail - good wheel interaction sample Figure 2.3: EMD and JNR time duration change with L/V ratios (from ref. [14]) Figure 2.4: L/V ratio change with AOA (from ref. [17]) Figure 2.5: L/V distance limit change with AOA (from ref. [17]) Figure 2.6: TGP8 new wheel profile gauge (ref. from [19]) Figure 2.7: Gauge No. 1 (ref. from [19]) Figure 2.8: Gauge No. 2(ref. from [19]) Figure 2.9: Switch radius gauge (ref. from [19]) Figure 2.10: Lehre (Gauge) A (ref. from [20]) Figure 2.11: Lehre (Gauge) B (ref. [20]) Figure 2.12: Lehre (Gauge) C (ref. [20]) Figure 3.1: Wheel - worn rail interaction viii

10 Figure 3.2: Force diagram at worn rail interface (from ref. [23]) Figure 4.1: Automated Switch Inspection Vehicle (ASIV) photo (from reference [21]) Figure 4.2: AAR1B New wheel profile (courtesy Norfolk Southern) Figure 4.3: AAR1B Moderately worn wheel profile (courtesy Norfolk Southern) Figure 4.4: Steps of proposed methodology Figure 4.5: Moderately Worn wheel and good switch point interaction Figure 4.6: Figure 4.7: Contact point face angle change in moderately worn wheel and good switch point interaction Allowable L/V ratios through the good switch point turnout with different lubrication levels Figure 4.8: Moderately worn wheel and damaged switch rail interaction Figure 4.9: Contact point face angle change in moderately worn wheel and damaged switch point interaction Figure 4.10: Allowable L/V ratios through the damaged switch point turnout with different lubrication levels Figure 4.11: Moderately worn wheel and yard switch rail interaction at 2" Figure 4.12: Contact point face angle change in moderately worn wheel and yard switch point Figure 4.13: Allowable L/V ratios through the yard switch point turnout with different lubrication levels Figure 4.14: Moderately worn wheel and worn switch rail interaction at 9" Figure 4.15: Contact point face angle change in moderately worn wheel and worn switch point sample 1 interaction ix

11 Figure 4.16: Allowable L/V ratios through the worn switch point turnout sample 1with different lubrication levels Figure 4.17: Moderately worn wheel and worn switch rail interaction at 16" Figure 4.18: Contact point face angle change in moderately worn wheel and worn switch point interaction Figure 4.19: Allowable L/V ratios through the worn switch point turnout sample 2 with different lubrication levels Figure 4.20: New wheel and good switch point interaction at 10" Figure 4.21: Contact point face angle change in new wheel and good switch point interaction Figure 4.22: Allowable L/V ratios through the particular turnout with different lubrication levels Figure 4.23: New wheel and damaged switch point interaction Figure 4.24: Contact point face angle change in new wheel and damaged switch point interaction Figure 4.25: Allowable L/V ratios through the particular turnout with different lubrication levels Figure 4.26: New wheel and yard switch point interaction Figure 4.27: Contact point face angle change in new wheel and damaged switch point interaction Figure 4.28: Allowable L/V ratios through the particular turnout with different lubrication levels Figure 4.29: New wheel and worn switch point sample 1 interaction Figure 4.30: Contact point face angle change in new wheel and worn switch point sample 1 interaction x

12 Figure 4.31: Allowable L/V ratios through the particular turnout with different lubrication levels Figure 4.32: New wheel and worn switch point - sample 2 interaction Figure 4.33: Contact point face angle change in new wheel and worn switch point sample 2 interaction Figure 4.34: Allowable L/V ratios through the particular turnout with different lubrication levels Figure 5.1: TGAAR1B new wheel gauge Figure 5.2: Gauge No. 1 - excessive stock rail check Figure 5.3: Gauge No. 2 - damaged switch point check Figure 5.4: NS severely worn wheel Gauge Figure 5.5: Switch point radius gauge Figure 5.6: AAR1B Narrow wheel profile Figure 5.7: New wheel and good switch point interaction for the analysis of chipping distance Figure 5.8: Moderately worn wheel profile (courtesy Norfolk Southern) Figure 5.9: 3D TGAAR1B Worn wheel gauge Figure 5.10: Moderately worn wheel gauge Figure 5.11: 75 - Worn wheel gauge Figure 5.12: 80 - Worn wheel gauge Figure 6.1: Unrealistic rail profile as an example xi

13 ABSTRACT Railroad transportation has been very important for human being for last two centuries. Although it is known as one of the safest forms of land transportation systems; mechanical, operational, and human behavioral problems result in a significant number of derailments on US railroads every year. While a collision represents the impact between two trains in any direction, a derailment occurs when a wheel of a car runs off the track. One of the most common derailment cause category is wheel climb derailments. Wheel climb derailments can be results of wheel problems, rail problems and operational problems or combination of these. A significant percentage of the wheel climb derailments occurs at turnouts. Thus, it is vitally important to determine the conditions of switch points before a derailment occurs. In this study, a mechanism for wheel climb derailments has been applied to turnouts by using data taken from an Automated Switch Inspection Vehicle (ASIV) 1. This data was used to conduct a set of wheel climb analysis to determine the critical points through the specific turnouts and the risk of wheel climb derailment. This thesis introduces the background of this methodology, conducts an analysis of collected data, and discusses the results and conclusions of this analysis. This methodology will help to evaluate condition of any switch point. Furthermore, hand held switch point inspection tools were evaluated and modified as a part of an IDEA Transportation Research Board project to reduce derailments in turnouts, and they are also presented in this thesis as a remedy of reducing wheel climb derailment risk. The 1 The data has been supplied by HARSCO Rail. xii

14 author participated in this IDEA project, and conducted research on producing hand held tools for the US railroads. This thesis includes discussion of these newly generated tools. This study has an importance since it will change the inspection technique from visual type to a more reliable one. As a result of this study, critical locations that have a risk of wheel climb on turnouts are identified by the proposed methodology. The IDEA project outcomes also provided newly generated inspection tools to be used to inspect these critical points. xiii

15 Chapter 1 INTRODUCTION 1.1 Statement of the Problem Railroad transportation has been very important for human being for last two centuries. It has been developing technologically and becoming cheaper, safer, faster and more reliable. Although it is known as one of the safest forms of land transportation systems, there are still problems to be solved. Railway systems need preventions and solutions for mechanical, operational, and human behavioral problems. A significant number of derailments occur on US railroad tracks because of the abovementioned problems. While a collision represents the impact between two trains in any direction, a derailment occurs when a wheel of a car runs off the track. There are many reasons that can lead to a derailment. One of the most common derailment cause categories is wheel climb derailments. Wheel climb derailments are considered as track caused derailments, however they are usually combination of wheel, rail and operational conditions. Since it is broadly accepted that wheel climb derailment is a subcategory of track caused derailment, in this study it is considered as track caused derailments. Track caused derailments include switch point caused, wide gauge caused, track geometry caused, transverse fissure caused, detail fracture caused, etc. A significant percentage of the track-caused derailments occur at turnouts. Subject to more lateral forces, turnouts wear and degrade faster than straight tracks. There is a variety of causes for turnout derailments. The reason can be switch point defects, stock rail, switch mechanism, switch adjustment failure, frog 1

16 defects, switch point gap, etc. Table 1.1 shows the number of derailments at turnouts that happened in 2013 based on FRA defined causes [1]. Table 1.1 Number of derailments at turnouts based on causes (2013) Number of Causes Derailments Stock Rail 3 Switch Mechanism 9 Switch Adjust 16 Switch Point Defects 41 Frog 4 Switch Point Gap 14 Other 19 According to the Federal Railroad Administration (FRA) Safety Data [1], 41 switch point defectcaused derailments which is 39% of the turnout-caused derailments occurred in It can be said that switch point defect-caused derailments have the most probable occurrence at turnouts. Derailment causes at turnouts in 2013 Other Switch Point Gap Frog Switch Point Switch Adjust Switch Mechanism Stock Rail 3% 4% 8% 13% 15% 18% 39% Number of derailments Figure 1.1 Number of derailments at turnouts based on causes 2

17 1.2 Objectives of the Study Noting that switch point defect-caused derailments are the biggest part of the derailments at turnouts, the focus of this thesis is on examining the mechanisms of switch point-caused wheel climb derailments. Determining the critical points in advance would prevent economical and social consequences of derailments. Furthermore, a couple of recommendations are offered to reduce derailments at turnouts, specifically switch point derailments. In addition, some practical hand held inspection tools are also suggested. The following questions will be answered in this thesis: What is a wheel climb derailment? How does it occur at turnouts? What is the mathematical expression of wheel climb derailment mechanism? What are the thresholds for avoiding it? What technologies are being used to determine conditions of switch points nowadays? How can we decide about the safety of a turnout? What type of graphics and tables can help to have an idea about a risk of derailment of a turnout? What is the current research on reducing derailments at switch points? 1.3 Overview of Turnouts and Definitions of Terms In this thesis, since the main focus is on turnouts; turnout components and other railroad terms are mentioned very often. Thus, an overview of turnout terminology and definitions of associated terms is provided in order to prevent confusion in reader's mind in this part. 3

18 1.3.1 Railroad Track A railroad track is a structure that supports the wheels of train cars that move on it. It consists of rails, fasteners, railroad ties, ballast and subballast foundations [2], [5] Wheels and Wheel Flange Wheels of the railroad cars enable trains to move on the railroad track. Wheel tread runs on rail. Wheel flange, on the other hand, is a down part of the wheel. (see figure 1.2) There are many different types of wheels in terms of width and dimensions (diameter, conicity2, etc.). There is a variety in width such as wide and narrow wheels, and diameters such as 26 in. to 36 in. The AAR 1B Narrow wheel profile is used for simulations in this thesis. Its coordinates are given in Appendix A-1. Wheel flange may contact with the rail in case of curving, wheel hunting, angle of attack, spiral negotiation etc. Flange contact is important for wheel climb derailment since the phenomena is initiated and developed in this location[3]. Figure 1.2 Wheel - Rail Interaction Overview and Components of Turnouts A turnout is a part of a railroad which has a mechanism that provides a change of direction for trains in the railroads. Figure 1.3 presents different parts of the turnout. Switch point is a part of 2 Conicity: The slope of the wheel tread or running surface relative to the axis of the wheelset [26]. 4

19 turnout that has ability to move and provide the change of track. Following are the components of turnouts: Figure 1.3 Turnouts and components (from ref. [4]) Stock rails The rail in which a switch point fits up against in the closed position [24]. There are two stock rails in the turnout. (see figure 1.3) Switch rails (point) The movable rails in a switch that provide a path for rolling stock wheels to transfer from one track to another [24]. There are two switch rails in the turnout. (see figure 1.3) Closure rails The lead rails connect the heels of a switch with the toe ends of a frog [24]. (see figure 1.3) Wing and Check (Guard) rails Wing and check rails assist the guidance of wheel sets through the crossing. (see figure 1.3) 5

20 Frog The portion of a turnout of track crossing where wheels cross from one track to another [24]. (see figure 1.3) Switch Heels Heel is the end of a switch rail which is the farthest point from the beginning of switch point in a turnout [24]. (see figure 1.3) Switch machines (Switch Head and Back Rods) Switching machines move switch rails from one side to the other (left to right or right to left) in order to guide trains. (see figure 1.3) Turnout Size The turnout size (number) which is also called as "frog number" is the number of units along the frog required to diverge one unit [27]. (see figure 1.4) Figure 1.4 Turnout size sample - No. 3 Turnout (from ref. [27]) 6

21 1.4 Organization of the Thesis This thesis is organized in the following form: In Chapter 2, a literature review which shows the development of the work on wheel climb phenomena and derailment prevention is presented and discussed for providing background information. This chapter is in two subchapters. One of them explains the literature of wheel climb derailment, while the other one summarizes a selected literature review on wheel climb prevention. Chapter 3 explains wheel climb failure mechanism. In this chapter, wheel climb mechanism is discussed in detail and more focus is given on L/V ratio threshold for wheel climb derailments. Chapter 4 discusses the methodology that is proposed for determining wheel climb critical points. The methodology includes analysis of L/V ratio of wheel-rail interactions and drawings from the results of analysis. Calculations are introduced and results are demonstrated. Then, graphs which show the thresholds and risky points for derailments are plotted. In Chapter 5, evaluation of newly produced hand held tools, which inspect switch point conditions, are explained. This chapter presents one of the project of the author participated in, and the results of that project and its importance. Finally, conclusions of Chapter 4 and Chapter 5 are drawn and what is left to be solved is given in Chapter 6. A couple of comments and suggestions is also stated in this chapter. 7

22 Chapter 2 LITERATURE REVIEW 2.1 Research on Wheel Climb Derailments Wheel climb phenomena has been investigated for two centuries by researchers. Wheel climb can be explained as climb of a wheel of a train car due to an excessive lateral load to vertical load ratio and passing onto over the top of the rail [6]. On the other hand, there has been a lot of work in finding solutions to reduce wheel climb derailments. Several wheel climb limit criteria has been proposed so far by researchers. While, Nadal's single -wheel L/V3 threshold criterion, Worn Rail L/V threshold criterion and Weinstock axle-sum L/V threshold criterion are based on quasi-static in L/V ratio criteria; Japanese National Railways (JNR) L/V time duration criterion, General Motors' Electromotive Division (EMD) L/V time duration criterion, FRA high-speed passenger distance limit criteria, Transportation Technology Center distance limit criterion and AAR chapter XI 50 milisecond (ms) time limit can be considered as in distance or time based dynamic limit criteria [7]. Each criteria will be briefly described in the followings: Nadal's single wheel L/V limit criterion This criterion was proposed by Nadal in 1908for French Railways [8]. Since then, it has been used widely by the railroad community and is currently the most commonly used of the different wheel climb criteria. Nadal's theory asserts that wheel starts to climb when the downward motion is stopped by a force with a saturated friction at the contact point. Based on this theory, the following equations have been derived [9] (see figure 2.1): 3 L/V: Lateral force to vertical force ratio of the wheels on the outer rail. 8

23 Figure 2.1 Wheel flange contact diagram (from reference [22]) L = Nsinδ - Fcosδ (2.1) V = Ncosδ + Fsinδ (2.2) F = fn (2.3) where L = Lateral Force V = Vertical Force N = Normal Force F = Force which is generated by coefficient of friction f = coefficient of friction δ = wheel flange contact point angle with the horizontal line = (2.4) When numerator and denominator are divided by cosδ, equation (2.4) becomes: = (2.5) Since Nadal criterion was proposed for the saturated condition such that F = f N = (2.6) 9

24 When numerator and denominator are divided by N, equation (2.6) becomes the famous Nadal's single wheel L/V limit criterion: = (2.7) This L/V ratio is the threshold of wheel climb initiation, beyond this limit wheel climb occurs. It also indicates that L/V threshold for wheel climb increases with the contact angle, and L/V threshold to wheel climb decreases with increase of coefficient of friction. In other words, wheel climb risk decreases when contact angle increase and coefficient of friction decrease Worn Rail L/V ratio This is a modification of the Nadal equation. Worn Rail L/V limit is the ratio of Lateral force to Vertical force when a wheel flange contacts with a worn switch point which has an angle on its gauge face. [10] Wheel climb occurs when the forces which push the wheel up is greater than the forces which push the wheel down. The formula for worn rail L/V threshold is given by [23] (see figure 2.2) : L/V < tan [ (90-Φ) - tan-1 (f) ] --> L/V < tan [ (β) - tan-1 (f) ] where f = coefficient of friction Φ = Worn rail contact point angle with the vertical line β = Worn rail contact point angle with the horizontal line 10 (2.8) (2.9)

25 Figure 2.2 Forces diagram on worn rail - good wheel interaction sample While Nadal L/V threshold is calculated using flange contact angle, in this study the angle of wheel contact point of running or switch rail is used to calculate L/V threshold. In this case, the risk of derailment increases with the increase of worn face angle in switch points or running rails Weinstock's Axle-Sum L/V limit criterion Weinstock proposed a less conservative L/V threshold criterion with respect to Nadal limit in 1984 [11]. He suggested to sum the L/V ratios of flanging wheel and non-flanging wheel. He thought this criteria would be more accurate since Nadal ratio gives so conservative limits. It is more accurate especially at small or negative angle of attacks4 because Nadal limit consideration was only flange wheel L/V ratio [12]. 4 Angle of attack : The angle between the rail and wheelset running direction [28]. 11

26 2.1.4 Japanese National Railways' L/V time duration criterion Japanese National Railway (JNR) researchers modified Nadal's criterion by adding a time duration in 1963 [13]. It is based on a single-flanging wheel analysis the same as Nadal criterion. They asserted that below 50 msec time duration L/V limit should be increased (see figure 2.3). The equation of stating such L/V limit is as in the following [25]: = π( )( ) ( ) (2.8) where ib : radius of gyration about longitudinal axis through contact point G : lateral distance between contact point, h : height of wheel flange, Pw : wheel load due to unsprung mass, g : gravitational acceleration, P : wheel load T : time duration of the impact or side thrust 10 L/V ratio and EMD Period of lateral thrust (s) Figure JNR 0.1 EMD and JNR time duration change with L/V ratios (from ref. [14]) 12

27 2.1.5 General Motors Electromotive Division's L/V time criterion General Motors' research team proposed an even less conservative L/V criterion for less than 50 msec time duration [14]. It is shown in the figure Association of American Railroads Wheel Climb Duration Limit Association of American Railroads (AAR) adopted a rule based on the combination of works of JNR and EMD research and considerable amount of field tests. The rule is called as AAR Chapter XI criterion. It states that "The individual wheel L/V should not exceed 1.0 on any wheels measured (Nadal Criteria). The instantaneous sum of absolute wheel L/V s on any axle shall not exceed 1.5 (Weinstock Criteria). And those values should not exceed for indicated value for a period greater that 50 msec per exceedence." [15] Federal Railroad Administration Wheel Climb Distance Limit Federal Railroad Administration (FRA) proposed a 5 ft wheel climb distance limit for any class 6 and higher type of railroad track [16]. This limit is reached by the gained experience of field tests and joint wheel climb research by AAR and FRA [12] TTCI Wheel Climb Distance Criterion Transportation Technology Centre, Inc. proposed two limits for wheel flange climb. One of them is the single wheel L/V limit and the other one is L/V distance limit. The wheel climb criterion was developed by using AAR1B wheel profile with a 75 wheel flange angle below 80 km/h (50 mph). The simulation graphs are illustrated in figures 2.4 and 2.5. This graphs indicate proposed single wheel L/V criterion as a function of angle of attack and L/V distance limit as a function of angle of attack [17]. 13

28 L/V Distance Limit (m) Wheel L/V ratio L/V < 1 when AOA > 5 mrad L/V < 12/[AOA (mrad) + 7] when AOA < 5 mrad Wheelset angle of attack (mrad) Figure 2.4 L/V ratio change with AOA 5 (from ref. [17]) L/V distance (m) < 4.88/(AOA +1.5) when AOA> -2 mrad msec duration at 80 km/k 50 msec duration at 40 km/k Wheelset angle of attack (mrad) Figure 2.5 L/V distance limit change with AOA 6 (from ref. [17]) 5 AOA : Angle of attack : The angle between the rail and wheelset running direction [28]. 6 AOA : Angle of attack : The angle between the rail and wheelset running direction [28]. 14

29 2.2 Research on Reducing Derailments at Turnouts in US Railroads A research team has conducted an important research for a TRB- IDEA project which is on switch point derailment reduction. The author of this thesis was a participant of this project. In order to clarify the vagueness of FRA standards about switch point condition inspection, they aimed to determine numerical values for derailment hazards and eventually produce inspection tools for switch points. In order to have an idea about determining standards, the team conducted a literature search for the other railroad standards in the rest of the world, specifically railroad companies of developed countries in terms of railroad industry. The team contacted with German, French, British and Swiss rail road companies to get the standards of them. British and Swiss rail companies agreed to share their standards with the team [18]. Here are the summaries of what inspection techniques British and Swiss railroad companies apply on the field to reduce derailments at switch point Network rail standards Network Rail is a company that operates British railroads. In Network Rail's standards, four hazards are specified as having risk of wheel climb derailments [19]. These are: Improper flange contact between wheel and switch point Improper switch rail profile Excessive switch point damage Excessive or unusual switch rail or stock rail wear In order to inspect these hazards, four gauges are used: TGP8 new wheel profile gauge : Checks no contact made below 60 line. (See fig. 2.6 [19]) 15

30 Figure 2.6 TGP8 new wheel profile gauge (ref. from [19]) Switch point wear Gauge No. 1 : Checks wear at the top of stock rail relative to the switch rail. (See fig. 2.7 [19]) Figure 2.7 Gauge No. 1 (ref. from [19]) Switch point wear gauge 2 : Checks switch point defect depth. (see fig. 2.8 [19]) 16

31 Figure 2.8 Gauge No. 2 (ref. from [19]) Switch radius gauge : Checks the switch point edge if there is a sharp corner. (see fig. 2.9 [19]) Figure 2.9 Switch radius gauge (ref. from [19]) Swiss rail standards Swiss Federal Railway (SBB) also determined the hazards and then produced associated inspection tools on switch points [20]. The hazards that they determined are similar to those are 17

32 determined in Network Rail. Here are the inspection tools that Swiss rail standards use for specific switch point conditions: Gauge A : Checks the relative height of the switch rail and stock rail through the switch point. (see fig [20]) Figure 2.10 Lehre (Gauge) A (ref. from [20]) Gauge B : Checks the magnitude of defects on switch rail along the switch point. ( see fig [20]) Figure 2.11 Lehre (Gauge) B (ref. [20]) Gauge C : Checks the gauge face wear angle of switch rail along the switch point. (see fig [20]) 18

33 Figure 2.12 Lehre (Gauge) C (ref. [20]) This literature review guided the team to adopt and modify the idea for the US railroads. Even though just British and Swiss railroad standards have been reviewed, it was agreed that it mostly reflects Europe's inspection methodology since the whole Europe railroad network is connected to each other. 19

34 Chapter 3 WHEEL CLIMB FAILURE MECHANISMS AT SWITCH POINT As it is stated in the previous chapters, there are several cases that can lead to wheel climb derailments associated with high L/V ratios. Curve radius, wheel-rail profiles, bogie suspension characteristics and vehicle speed can generate a wheelset angle of attack which can cause excessive lateral load. High L/V happens when the cars have excessive lateral force or too low vertical force [6]. Researchers have been working on wheel climb phenomena and tried to provide equations to explain it. It is mentioned in Chapter 2 that Nadal's formula, Worn rail formula, Weinstock's formula, Japanese National Railways' formula, GM Electromotive Division's formula, AAR, FRA and TTCI formulas are for indicating the limits for a wheel climb. While Nadal, Worn rail and Weinstock limits look only for L/V ratios, the other proposed limits look either for distance or for time duration of the wheel climb besides L/V ratios. Nadal Formula is the most conservative, practical and most commonly used wheel climb derailment formula among the others. The rest of the L/V ratio limit formulas expressed less conservative L/V limits considering Nadal has a very conservative one [12]. In this thesis, Nadal L/V ratio and associated worn rail threshold is chosen as a criteria for a wheel climb derailment because of the following reasons: -Weinstock L/V ratio limit can be expressed by axle wheelset-rail interaction data [11]. However, what is used in this thesis is a single wheel-rail interaction data. Thus, the data restriction does not allow to use Weinstock L/V ratio limit in data analysis. 20

35 - The rest of the proposed limits are either addition to Nadal's or Weinstock's limits by adding some distance or time duration criteria. Distance or time duration is not considered in our project, since the aim of the project is just to determine the critical points which is related to L/V ratio limit. Nadal Limit is used in Federal Railroad Administration (FRA) 's high speed track safety standards for reducing wheel climb derailment risk. According to this standard, the coefficient of friction of track is assumed to be 0.5, and L/V during testing should not exceed the threshold more than 5 ft. [22]. In this thesis, the focus of calculations is on worn switch points. Since Nadal limit is based on flange contact angle, the formula that is used should be modified into worn rail contact point angle. While Nadal limit is calculated by using flange contact angle, in this study angle of wheel contact point of switch rail is used to calculate wheel climb limit. Worn Rail L/V limit is the ratio of maximum allowable Lateral force to Vertical force when a wheel flange contacts with a worn switch point which has an angle on its gauge face. Wheel climb occurs when the forces which push the wheel up is greater than the forces which push the wheel down. (see fig. 3.1 [23]) Note that coefficient of friction is denoted by f in fig

36 Figure 3.1 Wheel - worn rail interaction (from ref. [23]) Figure 3.2 Force diagram at worn rail interface (from ref. [23]) From the forces diagram (see fig. 3.2 [23]), 22

37 Φ = gauge face wear angle f = coefficient of friction L = Lateral Force V = Vertical Force N = Normal Force Ftan = Force due to coefficient of friction L= -FtancosΦ +N.sinΦ, V=Ftan sinφ +N.cosΦ Nadal equation is as in the following : L / V = -FtancosΦ +N.sinΦ / Ftan sinφ +N.cosΦ Ftan / N = f L / V = (tanφ -f)/(1+f.tanφ) Modifying Nadal formula and bringing up it in only one tangential function : L/V < tan [ (90-Φ) - tan-1 (f) ] => L/V < tan ( β - f' ) where β = 90 - Φ (see figure 3.2) f = tan -1 (f) and f: coefficient of friction 23

38 Chapter 4 METHODOLOGY AND RESULTS The aim of this project is to show that accurate measurement of rail profile, such as by Automated Switch Inspection Vehicle (ASIV) (see fig. 4.1 [21]) data collection and using this data - by overlaying the different types of wheel profiles with obtained rail profiles - would help to understand the vulnerability of turnouts to wheel climb derailments. This methodology can be used to get the understanding of what points of an examined turnout is critical for wheel climb derailment in terms of Worn rail L/V ratio limits. On the other hand, determining the maximum allowable L/V ratios through the turnout is also aimed. Maximum allowable loads of the cars and corresponding speed limits would also be determined by knowing maximum allowable L/V ratios at turnouts. Figure 4.1 Automated Switch Inspection Vehicle (ASIV) photo (from reference [21]) 24

39 The calculation of L/V ratios has been done by overlaying each rail profile, which were obtained by ASIV cars, with each different wheel profile. In this project, AAR1B new (see fig. 4.2) and moderately worn (see fig. 4.3) wheel profiles have been used as wheel profiles Figure 4.2 AAR1B New wheel profile (courtesy Norfolk Southern) Figure 4.3 AAR1B Moderately worn wheel profile (courtesy Norfolk Southern) Following methodology has been applied in order to determine critical points through the turnouts: 1 - An overlay of the wheel and the rail profile has been done to determine the contact point considering the top of the stock rail touches the tread of the wheel. 2 - It has been ensured that the flange face point contacted with the rail face. 3 - The contact point coordinates on the rail face have been determined. 25

40 4 - Then, the switch point face angle has been calculated by using the coordinates of the contact points. 5 - Once the switch point face angle is determined, the worn rail L/V ratio formula can be applied to calculate L/V ratios at each section of the turnout. (see equation 4.1) 6 - Plots which show the change of maximum allowable L/V ratios along with the switch rail with different lubrication levels of the rail and rail face angle can be obtained once L/V ratios and gauge face angles have been determined throughout the turnout. As an illustrative example, figure 4.4 explains the steps of proposed methodology on moderately worn wheel rail interaction at the tip of a good switch point: Figure 4.4 Steps of proposed methodology 26

41 L/V ratio threshold formula: L/V < tan (β - f ) (4.1) where: L = Lateral wheel/rail force V = Vertical wheel/rail force β = 90 - Φ f = tan -1 (f) and f = coefficient of friction Different types of overlays will be illustrated with one point example in each type of overlays. They will be explained in the following sub-chapters. 4.1 Moderately Worn Wheel Overlays Good switch point - turnout This data has been obtained by an ASIV car on a specific good switch point - turnout ( number 26 ). This data includes the rail cross-section profiles from the beginning of the switch point to the end of the turnout in one inch increments. This particular turnout is 444 inches (37 ft) long. The examination on the turnout was based on finding L/V ratio threshold for wheel climb derailment as a function of gauge face wear angle applied all the way throughout the turnout. Critical points have been determined and placed in the summary table (see Table 4.1). The first inches of switch point could be a problem for the good switch point turnout with a moderately worn wheel interaction, so the L/V ratio results for each of the first 10 inches of the switch point profiles have been placed in the summary table. 27

42 Since the results of L/V ratios beyond the point of 25 inches are repetitive, the results have been placed in 25 in. distant based such as 50", 75", 100", 125", etc. The end point of the turnout was also included in the L/V ratio summary table. 1) Overlayed wheel and rail profiles As an illustrative example of the methodology, an overlay of the switch profile at 0" point of good switch with worn wheel is presented in figure 4.5 : Rail Profile Moderately Worn Wheel Profile Figure 4.5 Moderately Worn wheel and good switch point interaction 2) Determination of contact point coordinates: The contact point coordinates are determined to be: X coordinates Y coordinates ) Calculation of L/V ratio thresholds The L/V threshold formula is used : L/V < tan (β - f ) 28

43 At 0" point of good switch profiles with moderately worn wheel overlay: y1 - y0 = = x1 - x0 = ( ) = tan β = / = arc tan ( ) = > β =64.5 L/V ratio limits can be determined considering different coefficient of frictions since β is determined: f = > f = tan -1 (0.2) --> f = 11.3 f = > f = tan -1 (0.3) --> f = 16.7 f = > f = tan -1 (0.4) --> f = 21.8 f = > f = tan -1 (0.5) --> f = 26.6 Substituting into the equation : for f = 0.2 L/V < tan (β - f ) L/V < tan ( ) --> L/V < 1.34 for f = 0.3 L/V < tan (β - f ) L/V < tan ( ) --> L/V < 1.10 for f = 0.4 L/V < tan (β - f ) 29

44 L/V < tan ( ) --> L/V < 0.92 for f = 0.5 L/V < tan (β - f ) L/V < tan ( ) --> L/V < 0.78 Note, as coefficient of friction increases, L/V threshold decreases as expected from physical behavior that results in an increase of risk for wheel climb (see figure 4.7). Using contact gage face angle results, a graph of the change of contact face angle has been plotted (see fig. 4.6). Face angle change through the good-switch turnout with moderately worn wheel Face angle ( ) Face Angle Figure Distance from where the switch point starts (in) Contact point face angle change in moderately worn wheel and good switch point interaction 30

45 In the good switch point - turnout it is noted that after 300 in beyond the starting point there is no positive face angle which would never cause wheel climb derailments in terms of L/V ratios. Thus, the formula does not work to calculate L/V ratio thresholds in these profiles. Table 4.1 calculates L/V threshold for each location along the switch point. Figure 4.7 presents this change in L/V with distance graphically. Table 4.1 Summary of the good switch point-turnout - moderately worn wheel interaction β = 90-φ (degree) f(0.2) L/V [f(0.2)] f(0.3) L/V [f(0.3)] f=0.5 L/V [f=0.5] φ(degree) f=0.4 L/V [f(0.4)] x(in)

46 Allowable L/V ratios through the good-switch turnout L/V L/V [f=0.2] 2.50 L/V [f=0.3] 2.00 L/V [f=0.4] 1.50 L/V [f=0.5] Distance from where the switch point starts (in) Figure 4.7 Allowable L/V ratios through the good switch point turnout with different lubrication levels Damaged switch point - turnout This data has been obtained by an ASIV car on the field on a number 10 size turnout with a damaged switch point. L/V analysis has been applied in order to determine potential wheel climb locations and the severity. This data includes the rail cross-sections through the turnout with one inch increments. This particular turnout is 191 inches (16 ft) long. The examination on the turnout was based on finding L/V ratio threshold for wheel climb. The examination was applied all the way through the turnout and then the critical points are placed in a summary table. Again, since the damaged-switch point turnout with a moderately worn wheel interaction could be a problem in the first inches of switch point, the L/V ratio results for much of the first 10 inches of the switch point profiles are placed in the table. 32

47 Since the results of L/V ratios after the point of 25 inches are repetitive the results are placed in 25 in distant based such as 50, 75, 100, 125, etc. The end point of the turnout was also included in the L/V result table. 1) Overlayed wheel and rail profiles As an illustration overlay of point 0" is shown in the following figure: Damaged switch rail profile Moderately worn wheel profile -2-3 Figure Moderately worn wheel and damaged switch rail interaction 2) Determination of contact point coordinates: As an illustrative example : At 0" point of damaged-switch profiles with moderately worn wheel overlay: The contact point coordinates are determined to be: X coordinates Y coordinates

48 3) Calculation of L/V ratio thresholds The L/V threshold formula is used : L/V < tan (β - f ) So : y1 - y0 = = x1 - x0 = ( ) = tan β = / = arc tan ( ) = > β =73.7 L/V ratio limits can be determined considering different coefficient of frictions since β is determined: f = > f = tan -1 (0.2) --> f = 11.3 f = > f = tan -1 (0.3) --> f = 16.7 f = > f = tan -1 (0.4) --> f = 21.8 f = > f = tan -1 (0.5) --> f = 26.6 Substituting the equation for each level of lubrication : for f = 0.2 L/V < tan (β - f ) L/V < tan ( ) --> L/V < 1.91 for f = 0.3 L/V < tan (β - f ) L/V < tan ( ) --> L/V <

49 for f = 0.4 L/V < tan (β - f ) L/V < tan ( ) --> L/V < 1.28 for f = 0.5 L/V < tan (β - f ) L/V < tan ( ) --> L/V < 1.07 Note, as coefficient of friction increases, L/V threshold decreases as expected from physical behavior that results in an increase of risk for wheel climb (see figure 4.10). Furthermore, according to the contact face angle results the graph of the change of contact face angle is plotted. Face angle through the damaged-switch turnout with moderately worn wheel Face angle ( ) Figure 4.9 Distance from where the switch point starts (in) Contact point face angle change in moderately worn wheel and damaged switch point interaction 35

50 It should be noted that beyond 75 in from the starting point there is no positive face angle which would never cause wheel climb derailments in terms of L/V ratios. Thus, the formula does not work to calculate L/V ratio thresholds in these profiles. So, the L/V ratio columns for negative angles are blanked in the summary table. Table 4.2 calculates L/V threshold for each location along the switch point. Figure 4.10 presents this change in L/V with distance graphically. Table 4.2 interaction x(in) Summary of the damaged switch point-turnout - moderately worn wheel 90-φ φ(degree) (degree) f(0.2) L/V [f(0.2)] f(0.3) L/V [f(0.3)] f= L/V [f(0.4)] f= L/V [f=0.5]

51 Allowable L/V ratios through the damaged-switch turnout L/V L/V [f=0.2] 2.00 L/V [f=0.3] L/V [f=0.4] 1.50 L/V [f=0.5] Figure Distance from where the switch point starts (in) 100 Allowable L/V ratios through the damaged switch point turnout with different lubrication levels Yard switch point - turnout This data consists of rail cross section profiles for a small (number 8) turnout located in a yard. The data has been measured by the ASIV car. This particular yard switch point is 161 inches (13 ft) long. This data includes the rail crosssections through the turnout with a one inch increments. The L/V analysis applied all the way through the turnout and then the critical points are placed in a summary table. The same path with the previous samples was followed for this analysis, as well. The following is showing as an illustration of yard switch point and moderately worn wheel interaction at 2" point: 37

52 1) Overlayed wheel and rail profiles As an illustration, overlay of point 2" is shown in the figure 4.11: Yard switch rail profile Moderately worn wheel profile Figure 4.11 Moderately worn wheel and yard switch rail interaction at 2" 2) Determination of contact point coordinates: Continuing to the illustrative example : The contact point coordinates are given by: X coordinates Y coordinates ) Calculation of L/V ratio thresholds The L/V threshold formula is used : L/V < tan (β - f ) So : y1 - y0 = =

53 x1 - x0 = ( ) = tan β = / = arc tan ( ) = > β =76.5 L/V ratio limits can be determined considering different coefficient of frictions since β is determined: Substituting into the equation for each level of lubrication : for f = 0.2 L/V < tan (β - f ) L/V < tan ( ) --> L/V < 2.16 for f = 0.3 L/V < tan (β - f ) L/V < tan ( ) --> L/V < 1.72 for f = 0.4 L/V < tan (β - f ) L/V < tan ( ) --> L/V < 1.41 for f = 0.5 L/V < tan (β - f ) L/V < tan ( ) --> L/V <

54 Note, as coefficient of friction increases, L/V threshold decreases as expected from physical behavior that results in an increase of risk for wheel climb (see figure 4.13). Furthermore, according to the contact face angle results the graph of the change of contact face angle is plotted (see fig. 4.12). Face Angle through the yard-switch turnout with moderately worn wheel Face Angle ( ) Figure Distance from where the switch point starts (in) Contact point face angle change in moderately worn wheel and yard switch point It should be noted that beyond 100 in from the starting point there is no positive face angle which would never cause wheel climb derailments in terms of L/V ratios. Thus, the formula does not work to calculate L/V ratio thresholds in these profiles. So, the L/V ratio columns for negative angles are blanked in the summary table. Table 4.3 calculates L/V threshold for each location along the switch point. Figure 4.13 presents this change in L/V with distance graphically. 40

55 Table 4.3 x(in) Summary of the yard switch point-turnout - moderately worn wheel interaction 90-φ φ(degree) (degree) f(0.2) L/V [f(0.2)] f(0.3) L/V [f(0.3)] f= L/V [f(0.4)] f= L/V [f=0.5] Allowable L/V ratios through the yard-switch turnout L/V L/V [f=0.2] 2.50 L/V [f=0.3] 2.00 L/V [f=0.4] 1.50 L/V [f=0.5] Distance from where the switch point starts (in) Figure 4.13 Allowable L/V ratios through the yard switch point turnout with different lubrication levels 41

56 4.1.4 Worn switch - turnout sample 1 This data has been produced by an ASIV car on the field on a number 7.5 size worn turnout. L/V analysis has been applied to the observed data in order to determine the exact points of damages and the severity of them. This data includes the rail cross-sections through the turnout with one inch increments. This turnout is 275 inches (23 ft) long. The examination was applied all the way through the turnout and then the critical points were placed in the table. Same method with above applied for the summary table. 1) Overlayed wheel and rail profiles In order to show the severity of the damage in switch point, 9 in beyond form starting point of the switch point has been picked. At 9" point of worn switch profile with moderately worn wheel profile overlay is as the following: Sample 1 Worn switch rail profile Moderately worn wheel profile Figure 4.14 Moderately worn wheel and worn switch rail interaction at 9" 2) Determination of contact point coordinates: The contact point coordinates are determined to be: 42

57 X coordinates Y coordinates ) Calculation of L/V ratio thresholds The L/V threshold formula is used : L/V < tan (β - f ) At 0" point of good switch profiles with moderately worn wheel overlay: y1 - y0 = = x1 - x0 = = tan β = / = arc tan ( ) = > β =63.0 Substituting into the equation : for f = 0.2 L/V < tan (β - f ) L/V < tan ( ) --> L/V < 1.27 for f = 0.3 L/V < tan (β - f ) L/V < tan ( ) --> L/V < 1.05 for f =

58 L/V < tan (β - f ) L/V < tan ( ) --> L/V < 0.88 for f = 0.5 L/V < tan (β - f ) L/V < tan ( ) --> L/V < 0.74 Note, as coefficient of friction increases, L/V threshold decreases as expected from physical behavior that results in an increase of risk for wheel climb (see figure 4.16). Furthermore, according to the contact face angle results the graph of the change of contact face angle is plotted. Face angle through the worn switch-turnout sample 1 with moderately worn wheel Face Angle ( ) Figure Distance from where the switch point starts (in) Contact point face angle change in moderately worn wheel and worn switch point sample 1 interaction It should be noted that beyond 75 in from the starting point there is no positive face angle which would never cause wheel climb derailments in terms of L/V ratios. Thus, the formula does not 44

59 work to calculate L/V ratio thresholds in these profiles. So, the L/V ratio columns for negative angles are blanked in the summary table. Table 4.4 calculates L/V threshold for each location along the switch point. Figure 4.16 presents this change in L/V with distance graphically. Table 4.4 interaction x(in) φ(degree) Summary of the worn switch point sample 1 turnout - moderately worn wheel 90-φ (degree) f(0.2) L/V [f(0.2)] f(0.3) L/V [f(0.3)] f=0.4 L/V [f(0.4)] f=0.5 L/V [f=0.5]

60 Allowable L/V ratios through the worn switch-turnout sample L/V [f=0.2] 1.50 L/V [f=0.3] L/V L/V [f=0.4] 1.00 L/V [f=0.5] Distance from where the switch point starts (in) Figure 4.16 Allowable L/V ratios through the worn switch point turnout sample 1 with different lubrication levels It can be said that there is a wheel climb risk at 8 in. and 9 in. from starting point in dry condition of rail since the range of L/V ratio thresholds of these points are is 0.73 and Worn switch - turnout sample 2 This data has been produced by an ASIV car on the field on a worn number 7.5 size turnout. The difference between this turnout and is length of the turnouts. Rail sections also vary in these two samples. L/V analysis has been applied in the same way as it has been applied to previous samples. This turnout is 273 inches (23 ft) long. The examination applied all the way through the turnout and then the critical points were placed in the table. Same method with above applied for the summary table. 46

61 1) Overlayed wheel and rail profiles In order to show the severity of the damage in the point which is 16 in form starting point of the switch point was selected. At 16" point of worn switch profile with moderately worn wheel profile overlay is as the following: Sample 2 worn switch rail profile Moderately worn wheel profile Figure 4.17 Moderately worn wheel and worn switch rail interaction at 16" 2) Determination of contact point coordinates: The contact point coordinates are determined to be: X coordinates Y coordinates

62 3) Calculation of L/V ratio thresholds The L/V threshold formula is used : L/V < tan (β - f ) At 0" point of good switch profiles with moderately worn wheel overlay: y1 - y0 = = x1 - x0 = = tan β = / = arc tan ( ) = > β = 58.7 Substituting into the equation : for f = 0.2 L/V < tan (β - f ) L/V < tan ( ) --> L/V < 1.09 for f = 0.3 L/V < tan (β - f ) L/V < tan ( ) --> L/V < 0.90 for f = 0.4 L/V < tan (β - f ) L/V < tan ( ) --> L/V < 0.75 for f = 0.5 L/V < tan (β - f ) 48

63 L/V < tan ( ) --> L/V < 0.63 Note, as coefficient of friction increases, L/V threshold decreases as expected from physical behavior that results in an increase of risk for wheel climb (see figure 4.19). Furthermore, according to the contact face angle results the graph of the change of contact face angle is plotted. Face angle through the worn switch-turnout sample 2 with moderately worn wheel Face Angle ( ) Figure Distance from the switch poiint starts (in) Contact point face angle change in moderately worn wheel and worn switch point interaction It should be noted that beyond 75 in. from the starting point there is no positive face angle which would never cause wheel climb derailments in terms of L/V ratios. Thus, the formula does not work to calculate L/V ratio thresholds in these profiles. So, the L/V ratio columns for negative angles are blanked in the summary table. Table 4.5 calculates L/V threshold for each location along the switch point. Figure 4.19 presents this change in L/V with distance graphically. 49

64 Table 4.5 interaction x(in) φ(degree) Summary of the worn switch point sample 2 turnout - moderately worn wheel 90-φ (degree) f(0.2) L/V [f(0.2)] f0.3) L/V [f(0.3)] f=0.4 L/V [f(0.4)] f=0.5 L/V [f=0.5]

65 Allowable L/V ratios through the worn switch-turnout sample L/V [f=0.2] L/V 2.00 L/V [f=0.3] 1.50 L/V [f=0.4] 1.00 L/V [f=0.5] Distance from where the switch point starts (in) Figure 4.19 Allowable L/V ratios through the worn switch point turnout sample 2 with different lubrication levels It can be said that there is a risk for wheel climb between 8 in. and 19 in. from starting point in dry rail condition since the range of L/V ratio thresholds between these points are 0.63 to

66 4.2 New Wheel Overlays Good switch point - turnout 1) Overlayed wheel and rail profiles As an illustrative example of the methodology, an overlay of the switch profile at 10" point of good switch with new wheel is presented in figure Good switch rail profile New wheel profile Figure 4.20 New wheel and good switch point interaction at 10" 2) Determination of contact point coordinates: The contact point coordinates are determined to be : X coordinates Y coordinates ) Calculation of L/V ratio thresholds The L/V threshold formula is used : L/V < tan (β - f ) 52

67 At 10" point of good switch profiles with new wheel overlay: y1 - y0 = = x1 - x0 = ( ) = tan β = / = arc tan ( ) = > β =62.3 By determining β, L/V ratio thresholds can be determined considering different coefficient of frictions. Substituting into the equation : for f = 0.2 L/V < tan (β - f ) L/V < tan ( ) --> L/V < 1.23 for f = 0.3 L/V < tan (β - f ) L/V < tan ( ) --> L/V < 1.02 for f = 0.4 L/V < tan (β - f ) L/V < tan ( ) --> L/V < 0.85 for f = 0.5 L/V < tan (β - f ) 53

68 L/V < tan ( ) --> L/V < 0.72 Note, as coefficient of friction increases, L/V threshold decreases as expected from physical behavior that results in an increase of risk for wheel climb (see figure 4.22). Using contact gage face angle results, a graph of the change of contact face angle has been plotted (see figure 4.21). Face Angle change through the good-switch turnout with new wheel Face Angle( ) Distance from the switch point starts Figure 4.21 Contact point face angle change in new wheel and good switch point interaction Table 4.6 calculates L/V threshold for each location along the switch point. Figure 4.22 presents this change in L/V with distance graphically. 54

69 Table 4.6 Summary of the good switch point-turnout - new wheel interaction x(in) φ(degree) 90-φ (degree) f(0.2) L/V [f(0.2)] f(0.3) L/V [f(0.3)] f=0.4 L/V [f(0.4)] f=0.5 L/V [f=0.5]

70 Allowable L/V ratios through the good-switch turnout L/V [f=0.2] 2.50 L/V [f=0.3] 2.00 L/V [f=0.4] L/V L/V [f=0.5] 1.50 L/V [f=0.5] Distance from the switch point starts (in) Figure 4.22 Allowable L/V ratios through the particular turnout with different lubrication levels It can be stated that there is a wheel climb risk at10 in. and 15 in. from starting point in dry rail condition since the range of L/V ratio thresholds of these points are 0.72 and 0.70, respectively Damaged switch point - turnout 1) Overlayed wheel and rail profiles As an illustrative example of the methodology, an overlay of the switch profile at 7" point of good switch with new wheel is presented in figure

71 Damaged switch rail profile New wheel profile Figure 4.23 New wheel and damaged switch point interaction 2) Determination of contact point coordinates: The contact point coordinates are determined to be: X coordinates Y coordinates ) Calculation of L/V ratio thresholds The L/V threshold formula is used : L/V < tan (β - f ) At 7" point of damaged switch profiles with new wheel overlay: y1 - y0 = = x1 - x0 = ( ) = tan β = / = arc tan ( ) = > β =

72 By determining β, L/V ratio thresholds can be determined considering different coefficient of frictions. Substituting into the equation : for f = 0.2 L/V < tan (β - f ) L/V < tan ( ) --> L/V < 0.70 for f = 0.3 L/V < tan (β - f ) L/V < tan ( ) --> L/V < 0.57 for f = 0.4 L/V < tan (β - f ) L/V < tan ( ) --> L/V < 0.46 for f = 0.5 L/V < tan (β - f ) L/V < tan ( ) --> L/V < 0.36 Note, as coefficient of friction increases, L/V threshold decreases as expected from physical behavior that results in an increase of risk for wheel climb (see fig. 4.25). Using contact gage face angle results, a graph of the change of contact face angle has been plotted (see fig. 4.24). 58

73 Face Angle through the damaged-switch turnout with new wheel Face angle Figure 4.24 Distance from where the switch point starts (in) Contact point face angle change in new wheel and damaged switch point interaction Table 4.7 calculates L/V threshold for each location along the switch point. Figure 4.25 presents this change in L/V with distance graphically. It should be noted that beyond 109 in. from the starting point there is no positive face angle which would never cause wheel climb derailments in terms of L/V ratios. Thus, the formula does not work to calculate L/V ratio thresholds in these profiles. So, the L/V ratio columns for negative angles are blanked in the summary table. It should also be noted that highlighted points (from 100" to 109" beyond the starting point of switch point) indicate the unrealistic profile data of ASIV. These points are decided to be unrealistic with an ASIV professional and should not be considered as critical points. There is an actual critical point at 7" beyond starting point which shows 43.6 degree gage face angle. It corresponds a 0.36 L/V ratio at dry condition (f = 0.5) which definitely wheel will 59

74 climb. Side-worn rail profiles that can cause a wheel climb have also been obtained between points 75 in. to 85 in. Table 4.7 x(in) φ(degree) Summary of the damaged switch point-turnout - new wheel interaction 90-φ (degree) f(0.2) L/V [f(0.2)] f(0.3) L/V [f(0.3)] f=0.4 L/V [f0.4)] f=0.5 L/V [f=0.5]

75 Allowable L/V ratios through the damaged-switch turnout L/V L/V [f=0.2] 1.50 L/V [f=0.3] L/V [f=0.4] 1.00 L/V [f=0.5] Distance from where the switch point starts (in) Figure 4.25 Allowable L/V ratios through the particular turnout with different lubrication levels Yard switch point - turnout 1) Overlayed wheel and rail profiles As an illustrative example of the methodology, an overlay of the switch profile at 2" point of yard switch with new wheel is presented in figure

76 Yard switch profile New wheel profile Figure 4.26 New wheel and yard switch point interaction 2) Determination of contact point coordinates: The contact point coordinates are determined to be : X coordinates Y coordinates ) Calculation of L/V ratio thresholds The L/V threshold formula is used : L/V < tan (β - f ) 62

77 At 2" point of damaged switch profiles with new wheel overlay: y1 - y0 = = x1 - x0 = ( ) = tan β = / = arc tan ( ) = > β =63.7 By determining β, L/V ratio thresholds can be determined considering different coefficient of frictions. Substituting into the equation : for f = 0.2 L/V < tan (β - f ) L/V < tan ( ) --> L/V < 1.30 for f = 0.3 L/V < tan (β - f ) L/V < tan ( ) --> L/V < 1.07 for f = 0.4 L/V < tan (β - f ) L/V < tan ( ) --> L/V < 0.90 for f = 0.5 L/V < tan (β - f ) 63

78 L/V < tan ( ) --> L/V < 0.76 Note, as coefficient of friction increases, L/V threshold decreases as expected from physical behavior that results in an increase of risk for wheel climb (see figure 4.28). Using contact gage face angle results, a graph of the change of contact face angle has been plotted (see figure 4.27). Face angle change through the yard-switch turnout with new wheel Face angle ( ) Figure Distance from where the switch point starts (in) 200 Contact point face angle change in new wheel and damaged switch point interaction Table 9 calculates L/V threshold for each location along the switch point. Figure 4.28 presents this change in L/V with distance graphically. Note that highlighted points (from 145" to 161" from the starting point of switch point) indicate the unrealistic profile data of ASIV. These points should not be considered as critical points. 64

79 There are actual critical points at 1" and 2" beyond starting point which shows 29.4 and 26.3 degree gage face angles, respectively. It corresponds 0.67 and 0.76 L/V ratio at dry condition (f = 0.5) which have risk to wheel climb. It should be noted there is no positive face angle at 40 in. from the starting point which would never cause wheel climb derailments in terms of L/V ratios. Thus, the formula does not work to calculate L/V ratio thresholds in these profiles. So, the L/V ratio columns for negative angles are blanked in the summary table. Table 4.8 x(in) φ(degree) Summary of the yard switch point-turnout - new wheel interaction 90-φ (degree) f(0.2) L/V [f(0.2)] f(0.3) L/V [f(0.3)] f=0.4 L/V [f(0.4)] f=0.5 L/V [f=0.5]

80 Allowable L/V ratios through the yard-switch turnout L/V 4.00 L/V [f=0.2] 3.00 L/V [f=0.3] L/V [f=0.4] 2.00 L/V [f=0.5] Distance from where the switch point starts (in) Figure 4.28 Allowable L/V ratios through the particular turnout with different lubrication level Worn switch - turnout sample 1 1) Overlayed wheel and rail profiles As an illustrative example of the methodology, an overlay of the switch profile at 3" point of worn switch with new wheel is presented in figure

81 Worn switch point profile 1 New wheel profile Figure 4.29 New wheel and worn switch point sample 1 interaction 2) Determination of contact point coordinates: The contact point coordinates are determined to be: X coordinates Y coordinates ) Calculation of L/V ratio thresholds The L/V threshold formula is used : L/V < tan (β - f ) At 3" point of worn switch sample 1 profiles with new wheel overlay: y1 - y0 = = x1 - x0 = =

82 tan β = / = arc tan ( ) = > β =46.9 Substituting into the equation : for f = 0.2 L/V < tan (β - f ) L/V < tan ( ) --> L/V < 0.72 for f = 0.3 L/V < tan (β - f ) L/V < tan ( ) --> L/V < 0.58 for f = 0.4 L/V < tan (β - f ) L/V < tan ( ) --> L/V < 0.47 for f = 0.5 L/V < tan (β - f ) L/V < tan ( ) --> L/V < 0.37 Note, as coefficient of friction increases, L/V threshold decreases as expected from physical behavior that results in an increase of risk for wheel climb (see figure 4.31). Using contact gage face angle results, a graph of the change of contact face angle has been plotted (see figure 4.30). 68

83 Face angle change thorugh the worn-switch turnout sample 1 with a new wheel Face Angle( ) Figure Distance from where the switch point starts (in) Contact point face angle change in new wheel and worn switch point sample 1 interaction Table 4.9 calculates L/V threshold for each location along the switch point. Figure 4.31 presents this change in L/V with distance graphically. It should be noted that beyond 75 in. from the starting point there is no positive face angle which would never cause wheel climb derailments in terms of L/V ratios. Thus, the formula does not work to calculate L/V ratio thresholds in these profiles. So, the L/V ratio columns for negative angles are blanked in the summary table. There are actual critical points at 3, 4, 5, 6 and 7 in. away from switch point tip. Corresponding L/V ratio thresholds are 0.37, 0.41, 0.21, 0.40, 0.67 in a dry rail condition (f=0.5). These thresholds indicate that this particular turnout has a serious wheel climb risk which seems inevitable. 69

84 Table 4.9 x(in) φ(degree) Summary of the worn switch point-turnout sample 1- new wheel interaction 90-φ (degree) f(0.2) L/V [f(0.2)] f(0.3) L/V [f(0.3)] f=0.4 L/V [f(0.4)] f=0.5 L/V [f=0.5]

85 Allowable L/V ratios through the worn-switch turnout sample 1 with a new wheel L/V [f=0.2] L/V 2.50 L/V [f=0.3] 2.00 L/V [f=0.4] 1.50 L/V [f=0.5] Distance from where the switch point starts (in) Figure 4.31 Allowable L/V ratios through the particular turnout with different lubrication levels Worn switch - turnout sample 2 1) Overlayed wheel and rail profiles In order to show the severity of the damage in switch point, the point which is 3 in from starting point of the switch point was selected. At 3" point of worn switch profile with good wheel profile overlay is presented in fig : 71

86 Sample 2 worn wheel profile 1 New wheel profile Figure 4.32 New wheel and worn switch point - sample 2 interaction 2) Determination of contact point coordinates: The contact point coordinates are determined to be : X Coordinates Y coordinates ) Calculation of L/V ratio thresholds The L/V threshold formula is used : L/V < tan (β - f ) At 0" point of good switch profiles with moderately worn wheel overlay: y1 - y0 = =

87 x1 - x0 = = tan β = / = arc tan ( ) = > β =57.5 Substituting into the equation : for f = 0.2 L/V < tan (β - f ) L/V < tan ( ) --> L/V < 0.72 for f = 0.3 L/V < tan (β - f ) L/V < tan ( ) --> L/V < 0.58 for f = 0.4 L/V < tan (β - f ) L/V < tan ( ) --> L/V < 0.47 for f = 0.5 L/V < tan (β - f ) L/V < tan ( ) --> L/V < 0.37 Note, as coefficient of friction increases, L/V threshold decreases as expected from physical behavior that results in an increase of risk for wheel climb (see figure 4.34). Using contact gage face angle results, a graph of the change of contact face angle has been plotted (see figure 4.33). 73

88 Face angle change through the worn-switch turnout sample 2 with a new wheel Face Angle ( ) Distance from where the switch point starts (in) Figure 4.33 Contact point face angle change in new wheel and worn switch point sample 2 interaction Table 4.10 calculates L/V threshold for each location along the switch point. Figure 4.34 presents this change in L/V with distance graphically. There are actual critical points from 3" to 7" beyond starting point. The L/V ratios vary from 0.63 to 0.76 at these points at dry condition (f = 0.5) which carry a risk to wheel climb. It should be noted that at the first two inches and beyond 75 in. from the starting point there is no positive face angle which would never cause wheel climb derailments in terms of L/V ratios. Thus, the formula does not work to calculate L/V ratio thresholds in these profiles. So, the L/V ratio columns for negative angles are blanked in the summary table. 74

89 Table 4.10 x(in) φ(degree) Summary of the worn switch point-turnout sample 2 - new wheel interaction 90-φ (degree) f(0.2) L/V [f(0.2)] f(0.3) L/V [f(0.3)] f=0.4 L/V [f(0.4)] f=0.5 L/V [f=0.5]

90 Allowable L/V ratios through the worn-switch turnout sample L/V [f=0.2] L/V 2.50 L/V [f=0.3] 2.00 L/V [f=0.4] 1.50 L/V [f=0.5] Figure Allowable L/V ratios through the particular turnout with different lubrication levels 76

91 Chapter 5 SWITCH INSPECTION TOOLS The author of this thesis has been participating in a Transportation Research Board funded IDEA project that aims to produce hand held inspection tools for switch points to reduce derailments at turnouts. As the general concept of the project is explained in Chapter 2, it is an idea transferred from European railroads to US railroads. Since the rail and wheel types are different between two railroads, there was a need of modification and evaluations on inspection tools. British and Swiss inspection tools look for the same hazards at switch points, although there are some minor differences between these tools in shapes. Advisory committee of the IDEA project decided to work on British style of tools and modify them for US railroads since they are simpler and more practical than Swiss inspection tools. IDEA project advisory committee had three meetings and field analyses. First meeting was held in 23th of October, 2013, the second one was in 28th of January, 2014 and the last one was in 26th of March, In these field analyses, inspections tools which had been produced by Norfolk Southern (NS) research team were evaluated with different switch point conditions in Newark Chrysler yard. 5.1 IDEA Field Analysis 1 NS research team produced five gauges for the wheel climb derailment hazards which are mentioned in Chapter 2. These gauges are as follows: 77

92 1) TGAAR1B Gauge: This is the North American version of the Network rail gauge, using an AAR1B new wheel profile. As it is accepted in the Network rail, switch point contact below the 60 mark is an undesirable condition. (see figure 5.1) Contacting below the mark will lead to climb over the switch point to the stock rail. Figure 5.1 TGAAR1B new wheel gauge 2) Gauge No. 1: This gauge addressed stock rail head wear. It is applied in the first inches of switch point. When its flange part touches the switch rail, it indicates a fail. (see figure 5.2) Because, in that case the stock rail is worn excessively, thus the switch point is high enough for the wheel to climb. Figure 5.2 Gauge No. 1 - excessive stock rail check 78

93 3) Gauge No. 2: This gauge addressed chipped or damaged switch points. In this gauge, if bottom of the flange part does not touch the switch point, it is an unsafe condition which has excessive damage or chip that wheel can roll over onto it. This gauge is combined with Gauge No. 1 with one bar. (see figure 5.3) Figure 5.3 Gauge No. 2 - damaged switch point check 4) NS Worn Wheel Gauge: This gauge is independent from the British and Swiss railroad tools - it was produced by NS research team. The team produced using the actual dimensions of an existent worn wheel. It simulates a severely worn wheel, and looks for the wheel climb possibility. (see figure 5.4) It is applied moving back and forth the gauge, if it climbs because of the defects and wear of switch point it fails. 79

94 Figure 5.4 NS severely worn wheel Gauge 5) Switch point radius gauge (aka Pac Man): This gauge is similar with British radius gauge which looks for a sharp curve at the end of a switch point. If part C (see figure 2.9 and 5.5) does not touch with the rail it indicates a fail since the corner of the switch point is too sharp which can cause wheel climb. Figure 5.5 Switch point radius gauge 80

95 5.1.1 Results and Discussions After the field analysis, the committee met to discuss the evaluations of tools. Here is the results of first field analysis: 1. TGAAR1B profile was judged to be a useful tool since the switch point contact of wheel profile below 60 gives an undesirable condition, and could result a wheel climb. 2. Gauge No. 1 was judged to be not necessarily a good tool for US railroads. Because, it gave fails almost all conditions of switch points even if they are in good condition. 3. Gauge No. 2 was judged to be a good tool, but 0.65 inches distance from the top of the stock rail to the top of the switch point is valid for European wheels not for US wheels, so further analysis was needed to modify the distance from top of the stock rail to the top of the chipped switch point. It was also decided to change the gauge face angle of the paddle from 60 to 70 which is more closely US wheel types. This gauge was going to be evaluated with its modified dimensions in the following field evaluation. 4. NS worn wheel gauge was considered as a very useful tool, however, since it represented severely worn wheel condition it did not visualize a wheel climb phenomena. So, further analysis was needed to change the size of it. 5. Switch point radius gauge was judged to be not necessarily a useful tool for US railroads, because, the steel type which is used in the US switch points are not prone to have a sharp curve at the end of a switch point. 5.2 IDEA Field Analysis 2 In the light of first field evaluation and meeting, the second field analysis was held in 28th of January, 2014 in Newark Chrysler yard. The analyses and modifications which the author of this thesis and NS research team contributed as in the followings: 1) Gauge No. 2 81

96 Considering the gauge point of the wheel as a critical point to lead a wheel climb, the problematic distance is calculated as in the following: Figure 5.6 AAR1B Narrow wheel profile - Flange height = H = Distance from flange root to gauge line (contacts top of stock rail) = D = Distance from flange tip to gauge point = d = Distance from top of stock rail = H + D -d = for tape line of wheel add to get

97 5 4 Stock rail and switch rail AAR 1 B narrow wheel 0 gage point Maximum chipping distance = 0.70" Maximum point of rail: 3.95 Gage point:3.25 Figure 5.7 New wheel and good switch point interaction for the analysis of chipping distance So, the it was clarified that allowable chipping distance should be 0.70 inches. 2)NS Moderately Worn Wheel Gauge In the first field evaluations, it is observed that severely worn wheel profile flange height was unnecessarily high. NS Research team changed the length of flange of worn wheel profile to a moderate level which is 1.4 in. So, new moderately worn wheel profile looks as shown in figure 5.8, and the coordinates of it is in the Appendix A. 83

98 Figure 5.8 Moderately worn wheel profile (courtesy Norfolk Southern) 3) 3D TGAAR1B Worn wheel gauge This gauge is an independent gauge from the British and Swiss railway inspection tools. It was produced by NS research team (see figure 5.9). The aim of this gauge was to simulate wheel climb with a three dimensional severely worn wheel profile. The application was done by moving it back and forth and see if it climbed at first inches in switch points. Figure 5.9 3D TGAAR1B Worn wheel gauge 84

99 5.2.1 Results and Discussions After the evaluations on the field in 28th of January, 2014, the followings are agreed by the IDEA committee: 1. TGAAR1B profile was judged to be a useful tool as it was agreed in the first meeting. 2. Gauge No. 1 was judged to be not necessarily a good tool for US railroads as it was agreed in the first meeting. 3. Gauge No. 2 was judged to be a very useful tool. The modified chipping distance which is 0.70 in. and 70 gauge face angle of the paddle was agreed to be optimum dimensions. 4. NS severely worn wheel gauge was considered as a not useful tool with its current dimensions. It was decided to modify it and evaluate on the field in the next field evaluation which was going to be held in 26th of March. 5. NS moderately worn wheel gauge was considered as a very helpful tool. This profile is a modified version of TGP8 Network rail inspection tool with a moderately worn wheel profile. It was agreed that below 60 mark reflects an undesirable condition. The coordinates of this profile was also used in the proposed methodology. 6. Switch point radius gauge was judged to be not a useful tool for US railroads as it was agreed in the first meeting. 7. 3D TGAAR1B worn wheel gauge was judged to be not useful with its current shape, since it does not allow to see the climbing points and requires angle of attack with it. It was decided to modify it for the third field evaluations. 5.3 IDEA Field Analysis 3 Further necessary analyses have been done after the second meeting considering the meeting decisions. Third field analysis was held in Newark Chrysler Yard in 26th of March, 2014 based 85

100 on the first and second field evaluations and meetings. Two new gauges which were built by NS research team have been applied to different switch points in this field evaluation. After the field evaluation, a follow-up meeting has been held to discuss about the third field analysis and final results of this IDEA project. 1) AAR1B Moderately worn wheel gage: This gage was judged to be not necessarily useful by the committee members. Since it is not easy to decide pass or fail of a switch point by using this gage, it was decided to not to propose this gage as a useful inspection tool. (see figure 5.10) Figure 5.10 Moderately worn wheel gauge 2) 75 - Worn wheel gage: Based on the previous field evaluations of the worn wheel profiles (3D TGAAR1B worn wheel gauge and severely worn wheel gauge), NS Research team produced a new gauge to simulate a worn wheel (75 gage face angle) to test wheel climb at switch points. This gauge is applied at the tip of the switch point. It is an adjustable gage, the movable part simulates the steep flange of 86

101 a worn wheel and it is applied making sure it touches the stock rail on the rear side of it. If the switch point hits the bottom part of the gage, switch point fails since touching the switch points indicates the wheel flange can roll over the switch point, otherwise it passes. (see figure 5.11) Figure Worn wheel gauge 3) 80 - Worn wheel gauge: This gauge's shape, evaluation and application is similar to 75 worn wheel gage. The differences are such that steepness is 80 degrees in this gage and there is a little notch at the bottom to determine fail or pass. (see figure 5.12) The failing idea is the same as 75 worn wheel gage, as the bottom of the movable part touches top of the switch point the gage fails, otherwise it passes. 87

102 Figure Worn wheel gauge Results and Discussions After the third evaluation, which is the final evaluation for the IDEA project on the field, the advisory committee had a meeting to discuss about the third round of evaluations and decide the final results of the IDEA project. Followings are the outcomes from the IDEA project: 1. AAR1B New wheel gage: This gage was agreed to be a useful aid to show the proper wheel flange contact by all the committee members. It is one of the positive outcomes of the IDEA project. 2. AAR1B Moderately worn wheel gage: This gage was judged to be not as useful by the committee members. Since it was not easy to decide pass or fail of a switch with this gage, it was decided to not to propose this gage as an inspection tool Worn wheel gage: This gauge was agreed to be a useful aid. However, it gave fails at some points unnecessarily. Since there is a distance difference when the wheel gets into the switch point, there should be some distance for the tool from the stock rail (1/8 in. horizontally 88