Fractal analysis of high speed rail geometry data: A case study of Ankara-Eskişehir high speed rail

•An algorithm was developed for fractal analysis of track geometry graphs.•Medium wavelength track irregularities were quantified by fractal dimensions.•Short wavelength track irregularities were quantified by fractal dimensions.•Standard deviations and fractal dimensions of track geometry graphs were compared. By considering railway track geometry as a fractal pattern, the irregularity of the track geometry can be expressed numerically with the help of fractal dimensions. In this study, a novel algorithm based on ruler method has been developed and a program was written to determine the fractal dimensions of railway track geometry graphs. Four different fractal dimensions of DR1, DR2, DR3, and DR4 were proposed to determine the geometric irregularity of the railway track by using the data of Ankara-Eskişehir High-Speed Railway track. DR1 and DR2 were used to quantify short wavelength irregularities while DR3 and DR4 were used to quantify medium wavelength irregularities. At the end of the study, the relationship between fractal dimensions and standard deviation values, which is the quality indicator according to EN 13848-6, was investigated. According to this, there is a strong relationship between the DR3 and the standard deviation.