Dynamic Blocking for Railyards: Part II. Heterogeneous Traffic

Traffic through a railroad yard is said to be heterogeneous if all the destinations are not served with the same frequency. This paper presents a study of railroad yards when traffic is heterogeneous and stationary, that is, without rush hour (or rush day) phenomena. Destinations (blocks) are grouped into categories that are served with the same frequency. The number of blocks and the frequency corresponding to each class are the only traffic characteristics that need to be known to analyze a given yard. With this information it is easy to determine the minimum number of tracks needed, and the number of switches per car; a numerical example is provided. The minimum number of required tracks is always larger than that for homogeneous traffic, but under the right conditions, the number of switches can be smaller. An approximation for large numbers of blocks is used to isolate the traffic factors that make the number of switches either large or small.