Development of the condition dependent tamping process
Ballast, rails and sleepers form an elastic track system. This system is subject to elastic deformation as a consequence of tremendous traffic forces. When the deformations exceed the elastic limit of the system and the track in no longer laying in its correct geometrical position, precautions, e.g. temporary speed restrictions, have to be taken in order to enable a safe and comfortable travel.
Maintaining the track in regular intervals helps restore the initial system geometry, thus preventing possible uneconomical effects of lowering the speed limit. Track maintenance includes levelling, lifting, lining and tamping of the tracks, thus ensuring that the ideal geometry of the track is restored. This is performed by a tamping machine, with a system of non-synchronous, directional constant pressure tamping, where the tamping tines penetrate the ballast, and compact it under the sleeper with a squeezing movement. Forthwith after tamping, dynamic track stabilisation is performed in order to increase the density of the ballast under the sleepers and decrease the initial settlements.
The objective of this research project is to analyze and improve the relevant parameters for the compaction of ballast under the sleeper, as well as to determinate and optimize the factors responsible for the durability of the track geometry after the tamping process.
The research project described is developed as cooperation between the Institute of Geotechnics of the Vienna University of Technology, Plasser & Theurer - Export von Bahnbaumaschinen Gesellschaft m.b.H. and FCP Fritsch, Chiari & Partner ZT GmbH.
Univ.Ass. Dipl.-Ing. Olja Barbir