POLLACK PERIODICA An International Journal for Engineering and Information Sciences DOI: 10.1556/606.2017.12.3.13 Vol. 12, No. 3, pp. 141–156 (2017) www.akademiai.com HU ISSN 1788–1994 © 2017 Akadémiai Kiadó, Budapest DESCRIPTION OF RAIL TRACK GEOMETRY DETERIORATION PROCESS IN HUNGARIAN RAIL LINES NO. 1 AND NO. 140 Richárd NAGY Department of Transport Infrastructure, Széchenyi István University, Egyetem tér 1 H-9026 Gyr, Hungary, e-mail: nagy.richard@sze.hu Received 15 November 2016; accepted 6 June 2017 Abstract: The aim was the perfection of an analytic examination, which describes the track deterioration process, characterized the correspondences more precisely and better to use in practice. This method was based on the destruction’s theory of the railway track geometry and it exploited the possibilities of recent computer technology. More than one million measuring car (FMK-004) data were processed than analyzed and defined by configuring and programming a new method. The results of this method were descriptive functions, which afford interpretable information about the geometrically destruction’s occurrences of the different railway lines. Keywords: Rail geometric deterioration, Curve fitting with regression, Track dimensioning factor, Measuring and qualifying numbers, Deterioration time difference fraction, Reserve time, Qualification category 1. Introduction There are two geometrical denominations in connection with rail tracks. The first one is the absolute geometry, which is planned by the rail designing engineer in case of newly-built rails or rail reconstructions with alignment data, cross section data and long section data and realizes based on geodetic alignment [1], [2]. The second denomination is the relative rail geometry, which describes the position of rails to each other and to the basic lines and plane, so it shows the deviation compared to the error-free position [3]-[5]. The deterioration process of relative geometry is affected by several factors, which mostly come from traffic on it and from environmental effects [6]-[11]. The