PERFORMANCE OF A MOBILE, NON-CONTACTING, REFERENCE-FREE PROTOTYPE SYSTEM FOR RNT AND RAIL STRESS MEASUREMENTS

The use of Continuous Welded Rail (CWR) has become the industry standard in railroad tracks around the world due to the many advantages compared to the jointed rail. CWR, however, is susceptible to the development of internal forces in the rail due to thermal effects that can lead to track buckling or rail breaks. Railroads manage the internal stresses in the rail by setting, monitoring, and adjusting the rail neutral temperature (RNT) which is the temperature at which the rail is in a stress-free state. The existing methods in the industry to measure RNT are contacting, destructive, disruptive to railroad operations, and/or ineffective. The author has introduced a novel technique for estimating RNT that is based on shape and deformation measurements of the rail at different temperatures. The first generation of the prototype system acquired the said measurements using 3D Digital Image Correlation (StereoDIC) technology from a stationary platform. The second generation of the prototype comprises a moving platform and integrates a 3D laser profiler system for shape measurements. This paper and presentation discuss the unique challenges and solutions associated with mounting the system on a moving platform, along with the new testing protocol. The performance of the new mobile system is first assessed through laboratory studies in the indoor rail track testing facility at USC. Subsequently, the system is implemented and validated in the field. This paper presents the validation studies and discusses the performance of the system in the laboratory and the field along with the next steps in the development and implementation to practice.