Load Environment of Rail Joint Bars – Phase III: Assessment of the Effects of Installation and Maintenance Practices

A series of tests, aimed at assessing the structural integrity of joint bars under differing service conditions, were conducted to address concerns regarding joint bar failures in the revenue service environment. Data collected through the course of this study revealed that bending stress invoked by normal track surfacing operations is not a likely cause for cracks that initiate at the top center of joint bars. Instead, cracking at this location is probably the result of fatigue at the top center of the joint bar due to rail-joint contact. Surface hardening at the area of rail-joint contact was largely ineffective, resulting in metal flow developing adjacent to the easement at the top of the joint bar. Additional data gathered in this study suggests little correlation between the surface hardness of the joint bar and the depth of metal flow. Bending stresses and wheel/rail forces were also measured on joint bars used in rail end gaps and rail height mismatches, which revealed minimal effects on overall joint bar performance for the installation conditions and range of speeds evaluated.