Application of Optical Detection Methods for Top-of-Rail (TOR) Lubricity Evaluation on a Moving Platform for Revenue Service Track
Mast, Timothy Edward
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This research serves to evaluate the ability of optical detection techniques to ascertain the lubricity of revenue service track from a moving platform for railroad applications. A literature review is presented that covers the rail vehicle dynamics that drive the need of Top-of-Rail lubrication and directly affect the manner in which the Top-of-Rail Friction Modifiers (TORFM) and flange grease both spread down rail and eventually wear away. This literature review also highlights previous research in the field of rail lubrication and the benefits that rail lubricants, specifically TORFM, provide for the railroads. Finally, the literature review covers the governing optical principals inherent to the synchronous spot radiometer that has been developed for use in the research as a gloss ratio instrument and also addresses the drawbacks and challenges inherent to applying this type of instrument in the railroad industry. The research then overviews previous rail lubricity sensors developed by the Railway Technologies Laboratory (RTL) at Virginia Tech and the lessons learned from their application. The preceding field testing conducting with a modified second generation rail lubricity sensor and a rail push car is briefly summarized with emphasis on the drawbacks and issues that were used to develop the third generation sensor used for this research. The development of the third generation sensor is covered, including the issues that it attempts to solve from its predecessor and the governing optical principals that govern the operation of the sensor. The laboratory evaluations conducting to commission the sensor are also covered in preparation for deploying the new third generation sensor in medium speed, medium distance revenue service testing. This includes a shakedown run on a siding in Riverside, VA prior to conducting mainline in-service testing. Finally, this research thesis covers the in-service testing on revenue track conducted with the new third generation rail lubricity sensor and the accompanying remote-controlled (RC) rail cart. The two components, when combined, create a Lubricity Assessment System which is capable of being operated at speeds upwards of 10 mph remotely from a follow hy-rail truck. The data collected from this field test is analyzed for the lubricity assessments that are able to be drawn from this initial phase of field service testing. The conclusions from this testing affirm the ability of optical methods to determine and evaluate Top-of-Rail (TOR) lubricity from a moving platform. Specifically, the new sensor is able to identify several local phenomena that demonstrate the high potential for errant evaluation of rail lubricity evaluation from spot check based methods that are solved by evaluating the track in a continuous, moving fashion. Based on the continuous moving data collected for this test, several new signal traits such as the spatial frequency (wavenumber) associated with the passing freight cart wheels in the lubricity signal and the phantom applicator effect of transient lubricity conditions at the entrances and exits of curves can be detected and investigated. The success of this research indicates the continued evaluation of lubricity signals from a moving platform is warranted and suggests the potential for introducing one of these systems to various track metrology cars deployed throughout the United States railroads.
General Audience Abstract
The United States railroads have been employing rail lubricants to the rails since the beginning of the industry and have recently, in the past 20 years, introduced another type of lubricant: Top-of-Rail Friction Modifiers (TORFM). TORFM creates a third body layer between the train wheels and the Top-of-Rail surface to minimize asset wear of both the wheel and rail and to increase the train efficiency. As the United States railroads embrace Precision Scheduled Railroading (PSR), increased train efficiency can allow the railroads to run longer trains with fewer locomotives. This increases the efficiency and capability of the rail network and also decreases the fuel burned and the amount of rail and wheel wear. TORFM has been proven to be effective and is widely adopted, but the railroads are still in need of tools to determine the presence and absence of these thin and often nearly invisible layers of lubricant on the rail surface. This research uses lasers as tool to quantify the level of lubrication of the rail surface. The presence of rail lubricants, such as TORFM, on the rail surface change the amount of light that is reflected and scattered off the shiny steel surface. These changes are often small but can be captured by photodetectors housed in the instrument. By plotting the detected sensor values, trends in the lubricity signal can be tracked and evaluated to determine the presence or absence of rail lubricants and assess the overall quality of lubrication on the rail at specific locations down track. The research in this thesis takes existing methods that were used for single spot inspections and adapts them to a moving platform. The moving platform is able to continuously scan the Top-of-Rail surface as the instrument moves along and generates continuous moving evaluations of rail lubricity. This can be especially important when the lubricity is not uniform and allows for trends in the data to be analyzed to provide more consistent and precise evaluations of the lubricity trends down rail. Optical tools like this sensor, which are by nature non-contact sensors, can easily be adapted to existing track measurement railcars and deployed system wide. This solves a strong need for railroad engineers: to be able to identify the presence of rail lubricants and evaluate the effectiveness of their lubrication practices.
- Masters Theses