# A Methodology Linking Tamping Processes and Railway Track Behaviour
###### Abstract  
Today's railway transport is built upon high-performance infrastructure. Cost-effective yet sustainable infrastructure presumes tracks with a precise and durable geometry. At ballasted tracks, the geometry is created and restored through tamping machines, which position the track panel and compact the ballast beneath the sleepers. It is commonly agreed that the ballast compaction plays an important role in the long-term stability of the track. Yet, there is no method available which allows a direct correlation between the compactness of the ballast and the stability of the track geometry. Available studies either model track behaviour without considering the bedding, or analyse ballast compactness locally while disregarding its influence on the track geometry. This paper presents a new methodology which establishes a relation between these two topics--ballast compaction during tamping and subsequent track behaviour. A state-of-the-art tamping machine has been equipped with an experimental measurement setup, constantly recording relevant data during every tamping process. These data can be used to derive an indication for the achieved compaction under every sleeper. Utilising the tamping machine's internal measuring system for track geometry documentation, every tamping process (every sleep) is assigned to the precise position along the track. The data set is merged and synchronised with regular track geometry measurements of the infrastructure manager. The result is a comprehensive data set which allows precise analyses between tamping machine measurements and track behaviour. This data set provides the foundation for future research, aiming towards a better understanding of the tamping process and its influence on the quality and durability of the established track geometry. track quality; track behaviour; tamping process; ballast compaction; ballast condition 202320132137[[https://doi.org/10.3390/app13042137](https://doi.org/10.3390/app13042137)]([https://doi.org/10.3390/app13042137](https://doi.org/10.3390/app13042137))  
10 January 20231 February 20231  
comprises mechanised tamping. As levelling-lining-tamping defines the track geometry, this process is highly relevant for the quality and longevity of the tracks. Accordingly, tamping operations affect the life cycle costs of the entire railway infrastructure to a significant extent [3; 4; 5]. Hence, a lot of research has been conducted in the field of track deterioration modelling and maintenance planning, oftentimes focusing on the prediction of the optimal point in time for the next tamping intervention (e.g., [6; 7; 8; 9]). Some models also expand the projection period beyond the next tamping operation, which requires estimating the new track geometry quality after the next tamping operation. Typically, the track behaviour and the ultimate quality before tamping are considered decisive for the track quality after tamping [9; 10; 11]. However, this approach compulsorily implicates uncertainties in the prediction as the influence of the tamping process itself is entirely disregarded. Crucial parameters of the tamping processes--e.g., lifting of the track panel, number of squeezing processes per sleeper, squeezing time--have never been considered in previous investigations. Yet, it is generally assumed that the working quality, and the ballast compaction achieved by the tamping tools in particular, strongly affects the stability of the tracks. This paper presents a novel methodology which creates a relation between the tamping process and the achieved ballast compaction on the one hand and the established track geometry quality on the other hand. Advancements in sensor technology allow for the recording of measurement data directly at the tamping tools during every tamping process. This information is then linked to the quality of the established track geometry.