Method for Avoiding Thermal Buckling in Rails
Lateral thermal buckling is a common cause of derailments in continuously welded rail (CWR) tracks. Since CWR tracks are constrained against the motion along the direction of travel, extreme temperature changes can induce compressive stresses in the rails that can lead to track buckling. According to the Federal Railroad Administration (FRA, 2015), there have been 5,977 rail accidents within the United States in the last three years. Of these, approximately 1% (58) are listed as being caused by rail buckling. In a buckling situation, the length of repair and readjustment can be quite large. Hence, to lessen the costs of repair and assure the safety, there is a definite need to develop techniques for avoiding thermal buckling in rails. Despite the large amount of research conducted in this area, the prediction of rail thermal buckling still remains complicated because of the nonlinear nature of the phenomenon and the large number of parameters affecting the problem.
Rail Neutral Temperature In-Situ Evaluation
Continuous welded rails (CWR) are rails that are welded together to become long continuous members that are fixed at both ends. When the ambient temperature significantly increases or decreases from the rail neutral temperature (RNT), the temperature at which the rails experience zero stress, the metal can expand and cause the rails to buckle, or contract and cause the rails to fracture. These effects can, in a worst-case scenario, result in train derailment. However, even installing CWR at a median ambient temperature does not guarantee that a rail will not buckle or fracture in the future, and it is sometimes necessary to reinstall the entire rail. A means of preventing these faults is to measure RNT and longitudinal rail stress of CWR to determine if the reinstallation of the entire rail is warranted to increase safety.