Development of the condition-based tamping process

With the continuous increase in passenger and freight rail traffic, ballast track maintenance is becoming an increasingly demanding task, and nowadays much of the track maintenance work is carried out with modern tamping machines. The process of lifting, levelling and asynchronous equal pressure tamping provides very good results in terms of continuous ballast compaction and restoration of the original track geometry. The most desirable method of track maintenance from an economic point of view is condition-based, whereby the decisive parameters should be adapted to the track condition found. However, modern tamping machines work with previously defined tamping parameter combinations, whereby only a few parameters can be adapted to the ballast bed condition. 

The investigations carried out within the framework of the research project deal with the fundamentals of the tamping process and the soil mechanical aspects of ballast compaction. To this end, a comprehensive investigation of the tamping process during regular track maintenance in different ballast conditions will be carried out, with a particular focus on the interaction between the tamping tine and the ballast matrix during ballast compaction. For the first time, these two components are considered on a vibration cycle scale and a new method for measuring and interpreting their force-displacement relationship is developed in the form of a working diagram.This representation makes it possible to determine tamping parameters such as reaction force and compaction energy resulting from a given set of tamping parameters. The comparison of tamping parameters between tamping machine applications at different locations allows a clear identification of the ballast bed condition due to its interaction with the tamping tine. 

This finding forms the basis for the future development of a condition-based tamping process in which the tamping parameters are adapted to the ballast condition measured by the machine during tamping.

Schematic representation of a tamping unit

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Doctoral Thesis of DI Dr. Olja Barbir in reposiTUm, opens an external URL in a new window.