Track stability and buckling - rail stress management

Abstract

Buckling of railroad track continues to be problematic for railway engineers and maintenance personnel across all railway networks. Thermal forces are the principal longitudinal load on railroad track. In an effort to ensure track stability under dynamic loads, the magnitude to which longitudinal thermal stresses develop is controlled by the choice of an appropriate Design Neutral Temperature (DNT). The longitudinal movement of rail, referred to as creep, causes a deviation of the rails’ neutral temperature (RNT) from that of the DNT. It is crucial that the RNT is maintained at or near the DNT to provide the necessary leeway for dynamic traffic loads and ensure lateral stability of the track. However, techniques for monitoring the RNT are very limited and difficult to employ. Railway networks generally rely on preventative measures, such as track strengthening work, to control the risk of buckles occurring. This approach to managing the risk of track buckles is resource hungry and time consuming. This project develops a recursive methodology for identifying situations where the longitudinal movement of rail is likely to result in the accumulation of longitudinal stresses, which is conducive to buckling. The methodology has been developed for the Western and South-Western systems of Queensland Rail. The approach presented in this paper focuses on identifying certain trends in rail creep observed at locations that result in the development of stress condition that are conducive to buckling. The trends in the rate and extent of creep displayed at the locations and the locations’ proximity to fixed track structures are used to predict potential high stress areas.