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Description
Infrared thermography is a reliable, non-destructive method for assessing the condition of ballasted railway track superstructures, with proven applicability in evaluating ballast and concrete sleeper condition as well as switch heater functionality. Fine particles generated by the fragmentation of ballast material under traffic loading accumulate within the ballast bed, reducing its strength and preventing efficient drainage; therefore, the condition of the ballast needs to be monitored regularly. This paper presents an analysis of ballast condition using infrared thermography conducted on a railway track section in the city of Zagreb. Measurements were performed using a Fluke TiS45 infrared camera to correlate recorded surface temperatures with the condition of the railway ballast. The key assumption is that the thermal properties of clean ballast differ from those of fouled ballast due to differences in fine particle content. The accumulation of fines in fouled ballast promotes water retention, resulting in lower ballast temperatures. This paper also examines the potential use of infrared thermography to detect water retention zones in urban railway tracks integrated into road surfaces and enclosed to the rail head level with precast concrete slabs. In these track configurations, effective drainage is difficult to achieve, leading to localized water accumulation that promotes aggressive corrosion of rails and fastening system components. Localized water retention causes capillary rise of moisture within the concrete slabs enclosing the track structure, which appears as reduced surface temperature in thermographic images.
