The congestion on the tracks are increasing and to plan all requested trains on the tracks become harder. The infrastructure manager must have good methods for ruling out which operator gets its requested timetable. These methods must maximise the welfare and the decision must also be fully transparent to the operators. The aim of this paper is to develop and evaluate an optimization model for welfare cost. The welfare cost is minimised while considering the detailed constraints of the railway infrastructure. The resulting welfare cost can be used to perform a cost-benefit analysis to provide a value of possible future traffic. The cost-benefit analysis can be the base for several kinds of analyses, like finding the optimal number of departures or the best departure times, finding the economic value of a certain timetable, which are exemplified. The optimisation model is tested on a part of the Swedish railway network covering the entire area operated by the regional train operator Östgötatrafiken.