The purpose is to test the hypothesis that the choice of strategy for preventive maintenance of rail infrastructure might affect the amount of serious disruptions in the train traffic. The relation between preventive maintenance and serious train traffic disruptions can be divided into two parts. On one hand it is the relation between the chosen strategy for preventive maintenance and the state of the rail infrastructure. On the other hand it is the relation between the state of the rail infrastructure and the amount of occurring train traffic disruptions. Either the sub relations can be analysed and quantified separately or one might try to perform an analysis without dividing the relation between preventive maintenance and serious train traffic disruptions into two parts. An operational definition of serious disruption in train traffic in this context is that faults or damages on the rail infrastructure cause such severe delays that the planned turnover of train vehicles cannot be maintained, cancelled train traffic or the closure of a railway. Several methods for quantifying serious train traffic disruptions, based on available train traffic data, are suggested. It is clear from these methods that faults or damages on the overhead contact line dominate increasingly as higher weight is put on the larger train delays, while the opposite applies to faults and damages on signal system. The result of a Delphi study is presented, where two scenarios are tested. The purpose of the study is to let experts on maintenance of rail infrastructure judge to what extent the decision of preventive maintenance strategy may affect the amount of occurring train traffic disruptions. The first scenario means that the necessary maintenance strategy in order two reach the target standard for the rail infrastructure is implemented. In the second scenario a maintenance strategy is implemented that is 50 percent more ambitious than the strategy of the first scenario.