“Does god play dice with corrugations?”: Environmental effects on growth

Abstract Corrugation growth has perplexed many researchers for several decades with remaining challenges including its reliable prediction in the field. In the present paper, the effect of environmental variations on corrugation growth is investigated using field measurements and mechanics-based modelling. Statistically significant relationships between average daily rainfall, humidity and the growth of rail corrugation were investigated using meterological and railway site field monitoring of a metropolitan network test site with a recurring rail corrugation of about 95 mm wavelength. Corrugation growth rate ( G r ) was determined by systematically measuring the longitudinal rail profile with a Corrugation Analysis Trolley (CAT) on the 240 m radius, narrow gauge, concrete-sleepered curve. Both roughness generated and weld initiated profile growths were investigated. The weather data was obtained from records held by the Bureau of Meteorology. The modelling is developed to provide insight and mechanics based analysis of the field corrugation growth under changes in environmental conditions and vehicle speed variability. Results show a strong correlation between variations in rainfall and corrugation growth that is consistent with changes in steady state wear. Changes in contact patch geometry and the damage mechanism as the corrugation amplitude grows are shown to have substantial but slower effects on growth. The results are used to explain observed changes in corrugation growth rate under variable speed control at the same site.