In the last decades, maintenance of technical systems has become increasingly impor-

tant in many industries. Such systems are transport systems (rail, bus, airplane), civil

engineering systems (roads, buildings, bridges), health care (hospitals), communication

systems, manufacturing plants, etc. Failures of these systems may cause expensive pro-

duction losses and can have a negative e®ect on the environment and safety. For example,

a train accident, crash of an airplane, collapse of a building, computer breakdown in an

hospital, may cause large societal costs. Substantial environmental damage may result

from a failure i

Budai-Balke, G. (Gabriella)

In the last decades, maintenance of technical systems has become increasingly impor-

tant in many industries. Such systems are transport systems (rail, bus, airplane), civil

engineering systems (roads, buildings, bridges), health care (hospitals), communication

systems, manufacturing plants, etc. Failures of these systems may cause expensive pro-

duction losses and can have a negative e®ect on the environment and safety. For example,

a train accident, crash of an airplane, collapse of a building, computer breakdown in an

hospital, may cause large societal costs. Substantial environmental damage may result

from a failure in the chemical industry and an unanticipated breakdown of a production

system may cause large economic losses.

By corrective maintenance, including repairs and replacements of the failed compo-

nents, the failed system can be restored to an operational state. However, by preventive

maintenance actions, including condition monitoring, inspections, small repairs, these

failures can be prevented or their consequences can be reduced, but unfortunately the

failures can never be totally eliminated. As Kobbacy and Murthy (2007) remark, over

the last 50 years the approach to maintenance has been signi¯cantly changed. While over

a hundred years ago, the focus was mostly on corrective maintenance, after the Second

World War preventive maintenance gets increasingly more attention.

The costs for maintenance has increased over the years as well

Erasmus University Digital Repository

Propositionsattached to the dissertationOperations Research Models for Scheduling RailwayInfrastructure MaintenanceGabriella Budai–BalkeErasmus University Rotterdam4 June 2009IIntegrated planning of production and maintenance leads not only to a better under-standing of the relationship between these two most important aspects of any productionprocess, but also to considerable cost savings. However, the integrated planning requiresmore coordination that makes the problem more complex.Chapter 2 of this thesisIIProper and timely maintenance and renewal of the railway infrastructure is essential for asafe and efficient operation. In order to define what proper and timely maintenance andrenewal is, decision support systems need to be developed. Using these systems decisionssuch as when, where, to what, for which cost and how much maintenance and renewalshould be performed can be made in a structured and scientifically justified way. However,these decision support systems can only be successful when the infrastructure managersare convinced that these are just tools that can help them to do their jobs more efficiently.Chapter 3, 4 and 5 of this thesisIIIExtending the time between two consecutive executions of the same routine work to itsmaximal value may seem to lower the maintenance costs. Yet it is likely to create highermaintenance costs because there is less possibility to combine activities in one period.Chapter 4 of this thesisIVIn the literature, genetic and memetic algorithms are being seen as techniques suitable forsolving large scale scheduling problems due to their robust and fast search capabilities.Indeed, for the preventive maintenance scheduling problem, they prove to be faster thanthe exact method, however they are not as fast as simple greedy heuristics. Moreover, thetwo-phase opportunity-based heuristic, which combines genetic algorithm with a problemspecific algorithm, can still outperform them.Chapter 5 of this thesisVFinding a solution to the rolling stock rebalancing problem is challenging not only from ascientific, but also from a practical point of view.Chapter 6 of this thesisVIAs put by Clive James, “It is only when they go wrong that machines remind you howpowerful they are.”Unfortunately, this also applies to the assets of the railway infrastruc-ture.VIIConfidence in the banking sector can only return when the public can be persuaded thatno excessive risks are being pursued with their savings.VIIIThe more innovative a company, the better its chance to survive the present economiccrisis. However, this may not automatically be the case for companies in the financialsector, since (financial) innovation has been one of the major culprits for the crisis.IXThe communist regime in Romania unintentionally stimulated people’s creative skills.XThe disadvantage of speaking four languages is that after a while you end up with speakinga fifth language, which is the weighted average of the other four, the weights determinedand continuously readjusted by the frequency level of the usage.XIThe Hungarian language is very similar to Dutch - as long as your vocabulary is limitedto the twenty-or-so words that are the same in both languages.4

Operations Research Models for Scheduling Railway Infrastructure Maintenance

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