Additional Criteria of Change of Curvature and Temperature of Rails for Monitoring the Pre-Failure State of a Continuous Welded Rail in Plan

The article discusses proposals referring to a new way to control the state of a continuous welded rail.The main factors that have the greatest impact on the state of a continuous welded rail are displacement of rail and the state of a continuous welded rail in plan. This group of factors describes the temperature-stressed nature of operation of a continuous welded rail. Evaluated factors determining the properties which prevent displacement include the state of rail fastenings, the width of the shoulder of the ballast prism, the presence of hanging and unsupported sleepers, and fulness of the ballast cribs, space between the sleepers.The combination of these factors makes it possible to identify a complex coefficient with a high degree of reliability to assess the pre-failure state of a continuous welded rail associated with the risk of loss of stability of a continuous welded rail, the degree of danger of violation of train traffic safety.In order to assess the state of a continuous welded rail and the degree of its deterioration, the paper presents evaluation criteria. They allow getting a comprehensive picture of the state of any section of a continuous welded rail based on the results of its inspection by diagnostic tools and creating a list of recommendations to eliminate the identified violations.The paper highlights also the shortcomings of the existing methodology for assessing the state of a continuous welded rail in plan, which is based on the analysis of changes in the curvature of welded rails in plan in time. The retrospective analysis carried out by the author shows that there are cases of a sharp change in the state of a continuous welded rail in plan, which are currently not considered by the existing evaluation criteria. To increase detectability of such sections of a continuous welded rail, it is proposed to supplement the existing algorithm with additional evaluation criteria referring to changes in curvature of welded rails and in rail temperature, which allow timely identification of the places of a sharp change in the state in plan.Subsequent studies are suggested to establish the relationship between the rail temperature and the sites of a sharp change in the state of a continuous welded rail in plan.