Summary

Introduction
Over the past years a technically and economically optimised, and at the same time condition-related, strategy for permanent way maintenance has been developed with the Technical University of Graz. Essentially, this strategy is based on the overall considerations of the life-cycle costs of the track installations. All the costs of a track are taken into account on the basis of norm kilometres:

• Investment costs
• Maintenance costs
• Operational hindrance costs

and the optimum maintenance strategy is determined using an appraisal model.
A wide spectrum of types of installations are covered in the permanent way. This ranges from the track installations through bridges, tunnels, railway crossings, substructure formation right up to avalanche protection structures. In this presentation the strategies and processes are described with the example of track maintenance, although the complex correlations between all permanent way installations should not be disregarded.
When considering the different line categories, the methods for maintenance work and the optimum thresholds for action are laid down. Furthermore, the desired quality can only be achieved when strategic considerations are integrated into uninterrupted process sequences and when there is a balance of expenditure between technical services and business economy/controlling.
Comprehensive information systems are necessary to be able to establish all controlling parameters to achieve an optimum expert system for permanent way maintenance.

The Controlling Process
To be able to analyse the complete life cycle of track installations, it must be documented in an appropriate form. Thus it is necessary to be informed about the design and the initial quality, which many studies have proven should be as high as possible. Furthermore, information is required at all times on the actual condition of the track installations. These consist of the following components:

• measuring results from the track recording car,
• know-how and local knowledge of the maintenance staff and
• documentation of all work performed on the track

Track Quality Measurement
The process begins with the inspection of the track quality mainly with the aid of the track recording car and of the staff locally responsible for track quality.
The detailed description and ergonomic illustration of the relevant measuring data constitute
a central component in the controlling process of the permanent way maintenance. Finally, these data and the other information are analysed and combined to form a first rough plan.

Track Geometry
To improve the track position it is necessary to make an optimum track geometry. The target geometry of the track installations is calculated using appropriate EDP tools. Depending upon the situation, computer-assisted versine evaluation (RPA) is applied, or using geodetic data and the layout tool INRAIL. For a year we have been using the EM-SAT automatic track survey car to measure the actual track geometry. With the help of this self-propelled machine, we have been able to automate another stage in the complete process system of track maintenance. All these systems are linked via the central track geometry database and are therefore available for combined evaluations. For example, for the control of maintenance machines or for the list of the locally permissible speeds to calculate the timetables.

Machine control
When planning the deployment of heavy-duty railway machines a number of activities must be taken into account:
Contract management
Optimised site planning across the network
Machine deployment planning
Implementation of maintenance work
Post measurement, quality control
Feedback into the database

Conclusion
In order to implement optimum maintenance strategies, it is necessary to perform a process chain beginning with track recording, and continuing through planning, machine deployment planning, implementation and post measurement. Many methods and tools have been developed to assist the sequences.