Wheel Profile Maintenance Guidelines (2015)

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ACKNOWLEDGMENT This work was sponsored by the Federal Transit Administration (FTA) in cooperation with the Transit Development Corporation. It was conducted through the Transit Cooperative Research Program (TCRP), which is administered by the Transportation Research Board (TRB) of the National Academies. COPYRIGHT INFORMATION Authors herein are responsible for the authenticity of their materials and for obtaining written permissions from publishers or persons who own the copyright to any previously published or copyrighted material used herein. Cooperative Research Programs (CRP) grants permission to reproduce material in this publication for classroom and not-for-profit purposes. Permission is given with the understanding that none of the material will be used to imply TRB, AASHTO, FAA, FHWA, FRA, FTA, Transit Development Corporation, or AOC endorsement of a particular product, method, or practice. It is expected that those reproducing the material in this document for educational and not-for-profit uses will give appropriate acknowledgment of the source of any reprinted or reproduced material. For other uses of the material, request permission from CRP. DISCLAIMER The opinions and conclusions expressed or implied in this report are those of the researchers who performed the research. They are not necessarily those of the Transportation Research Board, the National Research Council, or the program sponsors. The information contained in this document was taken directly from the submission of the author(s). This material has not been edited by TRB.

The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished scholars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. Upon the authority of the charter granted to it by the Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scientific and technical matters. Dr. Ralph J. Cicerone is president of the National Academy of Sciences. The National Academy of Engineering was established in 1964, under the charter of the National Academy of Sciences, as a parallel organization of outstanding engineers. It is autonomous in its administration and in the selection of its members, sharing with the National Academy of Sciences the responsibility for advising the federal government. The National Academy of Engineering also sponsors engineering programs aimed at meeting national needs, encourages education and research, and recognizes the superior achievements of engineers. Dr. C. D. Mote, Jr., is president of the National Academy of Engineering. The Institute of Medicine was established in 1970 by the National Academy of Sciences to secure the services of eminent members of appropriate professions in the examination of policy matters pertaining to the health of the public. The Institute acts under the responsibility given to the National Academy of Sciences by its congressional charter to be an adviser to the federal government and, upon its own initiative, to identify issues of medical care, research, and education. Dr. Victor J. Dzau is president of the Institute of Medicine. The National Research Council was organized by the National Academy of Sciences in 1916 to associate the broad community of science and technology with the Academy’s purposes of furthering knowledge and advising the federal government. Functioning in accordance with general policies determined by the Academy, the Council has become the principal operating agency of both the National Academy of Sciences and the National Academy of Engineering in providing services to the government, the public, and the scientific and engineering communities. The Council is administered jointly by both Academies and the Institute of Medicine. Dr. Ralph J. Cicerone and Dr. C. D. Mote, Jr., are chair and vice chair, respectively, of the National Research Council. The Transportation Research Board is one of six major divisions of the National Research Council. The mission of the Transporta- tion Research Board is to provide leadership in transportation innovation and progress through research and information exchange, conducted within a setting that is objective, interdisciplinary, and multimodal. The Board’s varied activities annually engage about 7,000 engineers, scientists, and other transportation researchers and practitioners from the public and private sectors and academia, all of whom contribute their expertise in the public interest. The program is supported by state transportation departments, federal agencies including the component administrations of the U.S. Department of Transportation, and other organizations and individu- als interested in the development of transportation. www.TRB.org www.national-academies.org

Wheel Profile Maintenance Guidelines PART 1 Survey of Current Wheel Profiles and Maintenance Practices

Table of Contents TABLE OF CONTENTS ............................................................................................................................... i LIST OF FIGURES ...................................................................................................................................... ii LIST OF TABLES ....................................................................................................................................... iii ACKNOWLEDGMENTS ........................................................................................................................... iv SUMMARY .................................................................................................................................................. 1 CHAPTER 1 Introduction ............................................................................................................................ 2 CHAPTER 2 Transit System Maintenance Survey ..................................................................................... 3 2.1 Wheel Flats ............................................................................................................................ 3 2.2 Wheel Wear ............................................................................................................................ 4 2.3 Wheel Diameter Differences in One Axle ............................................................................. 7 2.4 Wheel Diameter Tolerance in One Truck ............................................................................ 10 2.5 Wheel Diameter Tolerance in One Car ................................................................................ 11 2.6 Wheel Flange Angle ............................................................................................................. 11 2.7 Other Wheel Inspections ...................................................................................................... 12 2.8 Wheel Truing ....................................................................................................................... 12 2.8.1 Truing Cycle and Wheel Life .................................................................................. 12 2.8.2 Truing Surface Roughness ...................................................................................... 13 2.8.3 Truing Templates .................................................................................................... 15 CHAPTER 3 State-of-the-Art Wheel Profile Design and Maintenance Principles ................................... 18 3.1 Wheel Profile Design Methodology ..................................................................................... 18 3.2 Wheel Profile Design and Maintenance Criteria .................................................................. 20 3.3 Wheel/Rail Contact Conicity ............................................................................................... 20 3.4 Correlation between Wheel Wear and Equivalent Conicity ................................................ 23 CHAPTER 4 Conclusions and Recommendations .................................................................................... 25 REFERENCES ........................................................................................................................................... 26 i

List of Figures Figure 1. Flat Spots on Two Wheels ....................................................................................3 Figure 2. Worn, Unworn Wheels, and Unworn Rail ...........................................................5 Figure 3. Freight Car Hollow Wheel Stability Test .............................................................7 Figure 4. Effect of Wheel Diameter Difference on Freight Car Stability (1 Tape equals 0.125 inch on the circumference) ....................................................8 Figure 5. Longitudinal Forces on the Right Wheel of the Leading Wheelset at 60 mph (96.6kmh) ....................................................................................................9 Figure 6. Effect of Mismatching Wheel Circumference on the Leading and Trailing Axle with Empty Freight Car and Pitch and Bounce Input .....................10 Figure 7. Milling Type Wheel Truing Machine.................................................................13 Figure 8. Lathe Type Wheel Truing Machine ...................................................................14 Figure 9. Rough Wheel Surface from Milling Type Truing Machine ...............................15 Figure10. New Wheel Contact on Worn High Rail ...........................................................16 Figure 11. Worn Wheel Contact on Worn High Rail ........................................................17 Figure 12. Wheel and Rail Contact Geometry ...................................................................20 Figure 13. Contact of New AAR-1B Narrow Flange Wheel on New AREMA 136RE Rail, 10-inch Crown Radius, 1:40 Cant, at a Gage of 56.5 inches ............22 Figure 14. Contact of Hollow Worn Wheel on Tangent Worn Track at a Gage of 56.5 inches................................................................................................22 Figure 15. RRD Functions Measured in a Freight Railcar ................................................24 ii

List of Tables Table 1. Lists of Rail Transit Agencies Surveyed ...............................................................2 Table 2. Details of Worn Wheels in Configuration 1 (Freight Car Stability Test) ..............6 Table 3. Details of Worn Wheels in Configuration 2 (Freight Car Stability Test) ..............6 Table 4. Transit Agency Wheel Diameter Tolerances .........................................................9 Table 5. Maximum Flange Angle of Transit Agency Designed Wheels ...........................11 Table 6. Transit Agency Wheel Truing Cycles and Wheel Life........................................12 iii

Acknowledgments The authors appreciate the Transit Cooperative Research Program for providing the funding for this work. We also thank TCRP D-7 committee members for their comments and suggestions and TTCI employees Nicholas Wilson, Michael Brown, and Program Manager Dingqing Li for their advice and project management. iv

TCRP WOD 65 Part 1 Summary Transportation Technology Center, Inc., (TTCI), a wholly owned subsidiary of the Association of American Railroads (AAR), conducted a survey on wheel profile maintenance practices in rail transit agencies, for the Transportation Research Board’s (TRB) Transit Cooperative Research Program (TCRP) as part of a project to develop wheel profile maintenance guidelines for transit operations. The first task of this project reviewed current wheel profiles and maintenance practices (including representative light rail and heavy rail transit agencies) through system visits and literature review. This report compiles the survey information from a questionnaire, site visits of transit agencies, information from previous TCRP projects, and state-of-the-art research results on wheel profile design and maintenance methodologies from a literature review. The following conclusions and recommendations are made from the Task 1 study: Wheel slide and wheel flats are mainly caused by braking and low adhesion conditions. New anti-slip technologies and devices are needed to reduce wheel flats. Wheel diameter difference on one axle has a significant effect on car lateral stability performance. Allowable wheel diameter difference maintenance limit depends on the vehicle and truck design, especially the truck suspension, and the maintenance limits of other components. Wheel diameter difference in one truck affects car vertical performance such as the wheel load equalization capability. Most transit agencies surveyed do not have wheel tread wear limits. Wheel wear has significant effects on vehicle and track performance. Setting up wear limits on wheels is a complicated issue. It depends on vehicle and track design, maintenance standards of truck components, and operation environment. New wheel design or truing templates should be optimized on the basis of existing rail wear conditions, vehicle design and maintenance standards, and special trackwork maintenance requirements. Wheel truing template profiles need to be evaluated periodically to take into account existing rail wear conditions. Rough surfaces on wheels from wheel truing can increase the risk of flange climb derailment. Smooth surfaces and lubrication could reduce the flange climb derailment risk. The effect of the following maintenance limits on rail car performance will be further investigated in Task 2 of this project: – Wheel diameter differences on one axle, one truck, and one car – Wheel wear and patterns – Multiple-axle wheel wear and patterns – Car type and suspension parameters – The nonlinear equivalent conicity function is a promising index to characterize variations of wheel/rail contact geometry caused by wheel wear or mismatching after truing. However, the correlation between the wheel wear or mismatched wheel diameter and the nonlinear equivalent conicity function has not been fully established. – The application of equivalent conicity defined in International Union of Railways UIC 518 and UIC 519 standards to North American rail transit vehicle performance assessment needs to be further investigated. Guidelines for wheel profile maintenance will be established in Task 2 of this project. 1

TCRP WOD 65 Part 1 C H A P T E R 1 Introduction The Transportation Technology Center, Inc. (TTCI) has conducted a “Wheel Profile Maintenance Guidelines for Transit System” project for the Transit Cooperative Research Program (TCRP). The objectives of this study were to: Investigate the effects of wheel profiles (include both new and worn profiles) on transit vehicle performance (safety and ride quality) Develop wheel profile maintenance guidelines for transit operations (light rail and heavy rail systems) Develop guideline implementation procedures for wheel profile maintenance demonstrated with examples The tasks of this project include the following: Task 1 – Survey current wheel profiles and maintenance practices Task 2 – Develop wheel profiles maintenance guidelines Task 3 – Demonstrate wheel maintenance guideline implementation procedures In Task 1, TTCI conducted a survey on current wheel profiles and maintenance practices in transit agencies through a questionnaire survey, site visits, and a literature review. The survey focused on wheel- related issues, including wheel defects, wheel profile design drawings and truing templates, wheel truing cycles, maintenance limit such as wheel hollowing, flange thickness, wheel diameter tolerance, rail grinding cycles, rail grinding objectives, and wheel and rail lubrication practices. This Task 1 report compiles the survey information from the recent questionnaire survey, site visits to rail transit agencies, survey information from a previous TCRP project (Wu et al. 2005), and state-of-the- art research results on wheel profile design and maintenance methodologies from the literature review. Table 1 lists the visited rail transit agencies, rail transit agencies responding to the questionnaire, and rail transit agencies visited in a previous TCRP project (Wu et al. 2005). Table 1. Lists of Rail Transit Agencies Surveyed Rail Transit Agencies Visited on Site with Wheel and Rail Profile Measurement Denver Regional Transportation District (RTD), Port Authority Trans-Hudson Corporation (PATH) Rail Transit Agencies Responding to the Questionnaire Houston Metro, San Francisco Bay Area Rapid Transit District (BART), RTD, PATH Rail Transit Agencies Surveyed in a Previous TCRP Project (Wu et al. 2005) Massachusetts Bay Transportation Authority (MBTA) New Jersey Transit Corporation (NJTC) Washington Metropolitan Area Transit Authority (WMATA) Southeastern Pennsylvania Transit Authority (SEPTA) Chicago Transit Authority (CTA) Chicago Metra 2

TCRP WOD 65 Part 1 C H A P T E R 2 Transit System Maintenance Survey Supporting the weight of a heavily loaded car, wheelsets withstand much abuse from extreme thermal (if tread braking is used) and mechanical stresses caused by such factors as brake shoe friction, pounding from rail joints and special trackwork, and wheel/rail forces. Both the wheel flange and the tapered tread provide forces on the contact points between wheel and rail to steer the wheel through curves and tangent track. Wheel/rail forces act positively to steer the vehicle; however, they also lead to rolling contact stresses that work negatively to cause wear, cracks, spalls, and shell defects on both wheels and rails. Wheel maintenance is critical for rail vehicle safety and ride quality. The following sections summarize wheel maintenance practices and standards used in different rail transit agencies. Brief descriptions of the theories related to wheel maintenance and standards are provided for a better understanding of the causes of the problems and the damages that might result. 2.1 Wheel Flats Almost every transit system surveyed has experienced wheel sliding, and consequently, wheel flat problems, as Figure 1 shows. Wheel flats are one of the main reasons for wheel truing. Other wheel defects caused by wear, such as uneven wear and thin flange, etc., also have to be removed by wheel truing. Figure 1. Flat Spots on Two Wheels 3

TCRP WOD 65 Part 1 When a wheel slides, frictional energy flows into the wheel through the contact patch. As soon as the wheel stops sliding, the overheated steel in the contact patch is quenched by the large thermal mass of the wheel. The steel in the contact patch transforms into martensite, which is a very hard but brittle phase of steel. As a result of the skid, the wheel has a flat spot at the martensitic area, causing an impact at each revolution. Cracks can further develop in and propagate through the martensite. When cracks branch together below the surface, the martensite piece breaks off the tread, leaving a spall on the wheel surface. Wheel slide is caused by velocity differences between wheel and rail; sliding can result from sticking brakes or because of heavy braking in low friction conditions. Wheel slide and flats are especially problematic during the fall season on some rail transit systems due to leaf residue contaminating the rails. Investigations showed contaminants, such as rust (iron oxides), dirt (silica and aluminum), and road salts (potassium, calcium, sodium, chlorine, and sulphur), petroleum oil products, and vegetable oils from pine and cedar trees, can form pastes with small amounts of water or oil and significantly reduce adhesion (Kumar 1997). Both traction and braking may lead to wheel slide. However, the existing literature and the TTCI survey interviews indicate that slides due to braking are more common. Magel and Kalousek (1998) report that skid flats for transit and passenger operations are due primarily to rapid and frequent brake applications under light axle loads, highly variable friction coefficients, and general over-capacity of the braking systems. Wheel flats not only generate significant impact forces that can damage track and degrade ride quality, but also increase noise. Significant maintenance efforts and cost have been devoted to reduce wheel slide and wheel flats. To control wheel slide and wheel flats, several techniques have been applied to mitigate the problems, including the following: Pressurized spray rail cleaners Hi-rail based wire brushes Sander operations Grit-filled gels (sandite) Both NJT and SEPTA use high-pressure washers. According to a NJT press release, it invested $420,000 in an AquaTrack device, which sprays 17 gallons per minute at 20,000 psi spray and uses two 250-horsepower engines on a flatcar (New Jersey Transit 2003). The AquaTrack operates primarily on the Morris & Essex and Montclair-Boonton lines (commuter rail). SEPTA cleans the track on light rail, Norristown, and commuter rail lines during their 3-hour overnight work window with a 5,000-psi high- pressure washer. In addition to spray cleaning, SEPTA also operates a gel and grit delivery system and manually places compressed sand disks (“torpedoes”) on its system in periods of severe weather. New Jersey Transit’s Newark City Subway had previously tried a modified rail grinder to wire brush its rails, but the results were not satisfactory. Kumar reports similar ineffectiveness (Kumar 1997). However, Chicago Metra regularly uses a Hi-Rail engine-powered brush on its Electric District and reports acceptable cleaning results. Chicago Metra also operates additional locomotives using sanders to clean the rails during severe weather conditions. Automated slip-slide control devices have greatly improved braking performance. These devices modulate one or more control parameters such as service braking pressures, dynamic brakes, motor torques, and sanding to adjust the brake forces or adhesion conditions. After employing such devices, Nelson and Wilson report wheel flats can be reduced by roughly 50 percent (Nelson and Wilson 1997). However, wheel flats still occur with a slip-slide system, and the technology needs to be further improved to reduce wheel flats. 2.2 Wheel Wear 4