Thermal imaging of railways to identify track sections prone to buckling

A technique is described to measure the spatial variation of rail temperatures with a view to highlighting sections of railway track prone to buckling in extreme temperatures. Thermal maps of a section of test track were produced by equipping a personnel carrier with a thermal imager and global positioning system (GPS). Temperature readings were taken using the rusted web (side) of the rail so that emissivity could be assumed constant. The results indicate that much of the spatial variation in daytime rail temperature can be explained by shading effects, with exposed sections of track on embankments being consistently the warmest and, therefore, the most prone to buckling. It is envisaged that the technique could be used to forecast the problem areas and will ultimately provide useful verification data for spatial modelling studies.