**4. Conclusions**

Track loading is a main trigger for track maintenance needs. Gross-tonnage is widely used, but cannot cover the different damage mechanisms properly. Damage processes on rails and in ballast are the most relevant causes for track maintenance. Dynamic vertical forces created by unevenness of track can be seen as loading for the ballast-related deterioration process, while rail surface damage and rail wear needs a more holistic description of the loading. Existing track deterioration models still need improvement, especially for new rail surface failures and for turnouts, but deliver a much more detailed insight on both track maintenance demand for changing traffic compositions and vehicle properties triggering track maintenance. Following this approach of a track deterioration model based on vehicle properties will help to forecast necessary track maintenance and the associated budgets much more precisely than the simplified gross-ton approach. The possibility to calculate track maintenance costs on vehicle basis enables of course also to allocate these costs much better in track access charge schemes [21, 33, 34]. This would support the construction and use of track-friendly vehicles and thus to reduce the costs of railway operation.
