Directions of optimization of train formation system are considered. The parameters describing transit traffic at statement of a problem of increase of range of purposes are established. Problems of increase of transit traffic for a station level are allocated. The technique of definition of potential transit traffic for linear range is considered. It is given a number of variants of train formation raising the transit traffic and its description is given. As criteria efficacy allowing to make comparison of various variants of train formation, it is offered to use term of delivery of correspondence to stations of destination and an expenses for delivery of correspondence from stations of train formation to stations of destination. Variants of formation of purposes are considered. Possible variants of a combination of correspondence in purposes are given. It is established superposable restrictions on variants of train formation: time for delivery of correspondence and the maximal number of purposes that simultaneously can be collected at the station.