Indirect determination of the measurement accuracy of the FMK-004 track geometry measuring car used on Hungarian rail network

During the examination of the Hungarian national network for the period from the 2nd half of 1999 to the 2nd half of 2013, had to answer to the reason why the geometrical errors are able to decrease, despite the fact that no regulation intervention was done on the line section during the study period. This anomaly leads us to the procedure in which it became important to determine the accuracy of the FMK-004 measuring car (FMK in English: railway superstructure measuring car). With the VBA code written for the research task, the data set was optimized, then deterioration functions were fitted to the data, and where outliers were detected, the extent of the outlier was analysed on a statistical basis. This determines the measurement accuracies for each of the three metrics separately. Furthermore, it can be clearly demonstrated by the examination of the national network that in 90% of cases there is a series of geometrics that have a value that decreases compared to the previous half-year, while other geometrics value still is increasing. (paper)