In this work, considering the MÁV’s (i.e., the Hungarian Railways) five small and five high-traffic railway lines, the statistical distribution and change of the track gauge parameter were analyzed, under a ten year, on time-series analysis, related to straight track sections. The analysed data, were bottom track gauge measurements, of the FMK-004 and FMK-007 type railway track geometry, measuring and recording car & wagon. Taking into account the railway tracks, the track gauge parameter cannot be controlled and improved upon by large machine methods, but its permitted value depends on the allowed speed (and vice versa). The main independent variables were the elapsed time and the through-rolled axle tons (as a function of time, i.e., the MGT). To generate the statistical analyses, Vaszary-like shape numbers were computed, considering the distribution functions of the measured data series of the track gauge parameter every 25 cm. The authors examined the change of the shape numbers, the average and standard deviation values of the track gauge, and the shape of the distribution functions (skewness and kurtosis properties). In the end, a spectrum analysis of the measured data series was produced. In conclusion, the Authors provide relevant statements regarding the track gauge parameter.