Full scale friction and durability testing of laser glazed rail

Friction forces at wheel/rail interfaces are a significant parasitic energy loss that affects the efficiency with which goods are transported via rail. This paper reviews the development of a laser glazing process that is designed to improve fuel efficiency by treating the gauge face of rails to minimize wheel/rail forces. This research involved activities to develop the laser glazing process, characterize the microstructure of glazed rail steel, assess friction forces with benchtop rigs, and perform full-scale friction force measurements with sets of full-scale instrumented railroad wheels. The full-scale tests performed at the Canadian National Research Council Centre for Surface Transportation Technology in Ottawa, Ontario were performed with two objectives: first to confirm friction reduction observed in earlier (Association of American Railroads - AAR) rolling/sliding tests (and in subsequent lab-scale tests), and second to confirm the adhesion of a glazed layer to the underlying rail under typical loads (up to 38,000 Ib). Demonstration of adhesion is critical not only for commercial acceptance of the process, but also for planning the next phase of research, which involves field tests of glazed rail segments. The full scale tests confirmed the reduction in friction observed in prior rolling-sliding, tests performed at the AAR/Pueblo facility, and in benchtop tests, with friction reductions up to 40%. Evidence of cracking was observed, thus raising concerns about durability; however, the extent and nature of the cracks were such that while they warrant further investigation, they should not preclude the field tests of glazed rail segments.