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4 CHAPTER 1: INTRODUCTION Rail corrosion, particularly at the base of the rail, is a serious problem in some North American transit systems. Rail base corrosion compromises the integrity of the rail and could result in catastrophic failures. In most cases, it is difficult to detect rail corrosion in the base because it is usually hidden between the tie plate and rail base. Ultrasonic detection systems are used for corrosion detection in many transit systems. However, ultrasonic testing is limited to the determination of the height of the rail, which limits considerably its implementation as a rail base corrosion detection method. Which is one of the main reasons why even the most modern and sophisticated rail flaw detection vehicles are limited in their ability to inspect the rail base for defects. Transit systems have also reported a susceptibility to metal loss at the rail base due to corrosion. The metal loss directly causes the rail to become more susceptible to failure. If undetected, the metal loss will result in a loss in structural strength due to a reduction in cross sectional area. This project was designed to conduct an industry survey to identify and document adverse effects currently experienced by the transit systems, to build an FEA and flaw growth model, and to create recommended guidelines for inspection, prevention, and monitoring of rail base corrosion based on the findings of the survey and FEA. An industry survey was performed to review current practices and problems associated with rail base corrosion. Currently, there are no available standards for rail base corrosion detection or prevention. Throughout this project, other alternative methods used by other industries, such as petrochemical and nuclear, were studied to identify technologies and standards (i.e., National Association of Corrosion Engineers, American Society of Mechanical Engineers, American Society for Testing and Materials) that can be easily implemented as recommended practices for rail base corrosion detection. Appendix A shows the questionnaire distributed for the survey. The survey focused on the prevention, maintenance, and practices followed by transit authorities to reduce the risk of failure due to rail base corrosion. Appendices B and C summarize the responses to the survey. This report provides recommended minimum guidelines to assist transit systems in detecting, monitoring, and preventing corrosion and metal loss at the base of the rail.
