Bärbel Jäger

Efficient maintenance strategy through System Dynamics

In times when economic efficiency of traffic systems is getting more and more important, it is necessary to have an efficient maintenance strategy, because maintenance costs have been identified as significant cost drivers. This holds true especially for railway signalling in which the long life cycle of elements has a high impact on the costs. In addition, a maintenance strategy is required to fulfil the high standards for availability and safety in the railway sector. While different strategies are available (e.g. corrective or preventive, predetermined or condition based, etc.), each strategy has various options of processed period, duration, costs, impact on the maintained item, etc. This makes it a difficult task to find an efficient maintenance strategy for a system or even a network. The Institute of Transportation Systems has therefore analysed cause-and-effect chains between system condition, availability, maintenance activities, and costs. The identified cause-and-effect chains are modelled with the use of System Dynamics. System Dynamics is a method which has established to analyse and model complex dynamic systems. The developed models do not only enable the user to compare the efficiency of different maintenance activities with each other, but also provide the possibility to determine a combination of these activities leading to an overall system maintenance strategy at a cost minimum through optimisation. This allows infrastructure managers to evaluate their current maintenance program and to determine an economically improved strategy for the future.

RAILONOMICS--Determining Investment Strategies for Railway Signalling through Simulation

This paper will discuss how the economical effect of an investment strategy in railway signaling is defined by the costs and revenues generated by the chosen system over its lifetime. While the cost positions relevant for an infrastructure manager can all be expressed in the performance figure Life Cycle Costs (LCC), only part of the revenue positions can be expressed monetarily. Therefore, it is necessary to also include non-monetary revenue positions when deciding on which railway signaling system to choose. Since most of the cost and revenue positions are closely linked to the system operation, the idea of using information from railway operation simulation software has been evolved. The Institute of Transportation Systems has therefore implemented a software link between the simulation software RailSy® and a new developed Cost-Benefit-Tool. With the latter the relevant life cycle cost and revenue positions of the evaluated signaling system and scenario can be captured, calculated and analyzed. This simulation-based evaluation of investment strategies for railway signaling is part of the RAILONOMICS® concept. RAILONOMICS® enables infrastructure managers to develop efficient investment and maintenance strategies in a structured manner.

Simulations-based Comparison of Train Control Systems

In this contribution a general purpose test facility for train control systems called RAIL LAB is presented. Due to the generic and modular approach this RAIL LAB can be used for the conformity test-ing of ERTMS/ETCS components. The on board unit and the trackside subsystem can be simulated or tested as real Hardware-in-the-loop component. The physical train and the railway network is substi-tuted by simulators. All the communication subsystems like Radio, Balise or Loop are replaced by simulators, which are based on transmission error models. For the validation of the operational safety and behaviour manual tests can be used as well as predefined test sequences. The current implementa-tion phase is related to the on board and the trackside part of the train control system, further steps are related e. g. to the driver desk and the interlocking interface.