A commuter train operator purchased a new fleet of trains in order to gradually replace older rolling stock. There were requirements on reliability and total operating cost, requiring commitments from the supplier regarding reliability performance and the operator regarding operation and maintenance.
Systecon consultants and the models OPUS10™ and SIMLOX were used to derive cost-efficient spare parts and to analyse and evaluate the requirements. The models evaluate availability based on a planned timetable, available resources, reliability performance and the maintenance plan.Performed analyses
Two alternative depot organisations were analysed using number of vehicles, train reliability estimates, operating profile etc. The maintenance resources and maintenance strategies were varied:
- The first included two depots, one with three repair tracks and two tracks in the other
- The second included three depots, one with three repair tracks and one track each in the others.
An important operator issue was the number of repair tracks needed to simultaneously maintain an acceptable availability and efficient resource utilisation. SIMLOX was used to analyse the number of tracks, their allocation to depots and deriving the optimal number. In this case five tracks turned out to be the most cost-efficient number.Maintenance solutions (preventive maintenance)
The commuter service availability depends on several factors. The maintenance solution is of major importance. The incentive is to plan maintenance to be performed during low (or no) traffic hours; a comparison was made between split maintenance and a traditional overhaul approach.
Cost-effective spare part allocations for the two alternatives with the same overall cost were calculated with OPUS10™. (Diagram A)
The spare parts results were transferred to SIMLOX and combined with additional information including maintenance activity duration times, amount of allocated maintenance personnel, transportation times of spares from depots, operating profiles etc.Results
Diagram B describes the traffic ‘volume’ achieved (yellow). The unavailability is presented in red and follows periods of low operation demands. The green areas symbolize trains ready but not in operation. Diagram C presents the causes for unavailability in a similar way.
The overall result from the study was that, given the stepwise improvement of maintenance plans and spares assortment, the difference between the studied ‘main’ alternatives is more than one per cent unit of availability. This corresponds to nearly two complete rail vehicles, which influenced the decision process for the client.
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