Assessing the Effects of Closure-Free Periods on Railway Intervention Costs and Service

Ensuring that railways provide excellent service requires the execution of maintenance interventions. As railway use intensifies, this becomes increasingly difficult due to the conflict between track possession used for train operation and the execution of interventions. One way to improve the consistency of train schedules, and thus user comfort, is to impose closure-free periods, in which no interventions are planned. The imposition of closure-free periods forces asset managers to group their interventions either before or after the closure-free periods. This encourages asset managers to exploit synergies between interventions which can reduce costs and the negative effects on users. However, it also means that maintenance interventions may need to be executed earlier or later than the times suggested when considering only their optimal life cycles. To deal with this issue, this paper investigated the effect of imposing closure-free periods on the development of intervention programs in terms of intervention costs and disruptions to service. We used a network-flow optimization model to determine the optimal intervention programs for a 5-year planning period without and with the imposition of a minimal 2-year closure-free period on a railway line in Switzerland. The effects of the closure-free period on intervention costs and service were discussed, along with the losses of executing interventions at different points in time from those suggested using optimal asset life cycles.