چكيده به لاتين
Railway planning includes issues of blocking, train formation, train scheduling, locomotive allocation and crew allocation, and so on. Due to the complexity of railway planning, in most cases these plans are done separately and in a specific sequence. For example, in train planning, train routing and scheduling is done before locomotive allocation. In other words, train scheduling is done without considering the locomotive allocation schedule. This type of hierarchical programming has a definite drawback, and that is that when the optimal output of one programming is used as input to the next programming, it cannot be concluded that we have achieved a global optimal solution. Therefore, the separation of train schedules and the allocation of locomotives from each other cause a weak coordination between the two, which may cause delays in the arrival of locomotives at the train station and delay in train departure, in which case it is necessary to reconsider the schedule. This poor coordination can also prevent us from making full use of the resources available when locomotives first arrive at the train station. In this paper, a comprehensive optimization model is presented that simultaneously determines the locomotive allocation to trains, the train schedule, and the routes on which the locomotive travels lightly (without transportation). Locomotives are also separated from the train and inspected after delivering the trains to their intended destinations. To solve this problem, a three-dimensional network of place-time-status is presented. In this network, "status" indicates which train the locomotive is connected to. This problem is formulated by the flow of a multi-commodity network, in which the commodities represent locomotives moving from the origin node (starting station) to the destination node (destination station). In this multi-commodity network, in addition to network constraints (supply, demand and equilibrium), rail network constraints are presented.
