**1. Introduction**

Asset Management aims for identifying and implementing a sustainable and costefficient track structure. Furthermore, this track structure needs proper maintenance in order to achieve a sustainable permanent way. However, the one "best track" does not exist as boundary conditions change. These conditions are described by different sets of parameters such as traffic load, subsoil condition, dewatering system, and many more. Thus every "best track" must be a sustainable solution for the given specific situation—sustainable from the technical perspective as well as from the economic one. This requires not just evaluating innovative technical solutions but also proving its economic efficiency, over the entire life cycle.

The evaluation needs a sound technical description of maintenance being then transposed into maintenance costs. The economic evaluation needs to give answer to the three main questions of asset management:


3.When should the entire track structure be reinvested? (Economic service life)

These questions cannot be answered separately as an investment strategy cannot be formulated without considering the maintenance demand, a maintenance strategy must be based on the specific investment, and the economic service life is a consequence of both investment and maintenance.

This results in a two-stage model: first, we need technical descriptions of different options describing investment, maintenance, and service life and thus track deterioration. Life cycle management is therefore a prerequisite for asset management. The second step is to transform the technical information into costs in order to identify the economically most sustainable solution from the different options. The presented Standard Element approach provides a strategic view and acts on average track behavior. To answer question 3 on project level, so for a specific track section somewhere in a network, the Standard Element approach is too general. In this case, we need to use on-site measurement data and deterioration function [1, 2]. The economic appraisement is similar.

Looking at the literature, we find a lot about the proper organization of maintenance within an asset management scheme [3–5]. The different options for applying maintenance as reactive, preventive, condition-based, or even predictive maintenance are well discussed in many papers. Besides these theoretical concepts, also maintenance scheduling for railway tracks is being analyzed and published [6–8].

Most scientific papers discuss track or component behavior, the wear- and damage processes, and the deterioration of components or the entire track. This is especially true for the ballast-related issues, mainly track geometry [9–11] and rail behavior [12–16]. While these papers study quality loss, maintenance is often not addressed. And if maintenance actions are covered, mainly the quality improvement is focused on [17–19] in order to identify if the maintenance action was successful or not. We also see papers dealing with proper intervention levels for different track maintenance actions [20–22].

However, maintenance frequencies for tracks facing different boundary conditions are rare and provide very rough and general figures. These maintenance frequencies are by far not sufficient to answer the questions of track asset management. Therefore, this paper delivers maintenance frequencies for varying boundary conditions, for different transport volumes, track radii, track components, and subsoil conditions.
