A Simulation Model to Analyze the Performance of Aprin Yard

The rail yard is responsible for receiving inbound freight, sorting it, and sending it to the next destination. Freight arrives at yards for four primary reasons, and, for each case, the processing steps differ. First, the freight may be connecting from one train to another. Second, the yard may be the final destination for arriving freight or the origin for departing freight. Third, the train upon which the freight is traveling may be simply passing through the yard in route to another destination. Finally, the train upon which the freight is arriving may require a mandatory safety inspection. In this paper, for the first time in Iran, a simulation model is developed for a flat classification yard. The proposed model is to analyze the performance of available resources in the flat classification yards. The inputs of model include: • number of receiving, classification and departure tracks, • number of switching locomotives, • probability distributions such as: of train arrival interval times, number of cars in each train, • types of incoming trains,• switching operation time, • inspection time, • stopping time, •etc.The presented model simulates the Aprin’s operations including car grouping, the train arrival, train making up and train departure processes. The main outputs of the model include: •total and average time spent in the yard, •total and average waiting time for sorting and making up trains, •utilization rate of switching locomotives,•etc.The current situation of Aprin’s operations is simulated. It is then used to validate the proposed simulation model. To analyze the performance of Aprin yard and to examine the availability of resources the number of switching locomotives and car incoming rates were changed and the treats of the system were studied. The proposed model can serve as a reliable tool to analyze and decide for the increase of facilities and equipment in the classification yard.