Railway transportations becomes again to be seen as an efficient and environmentally friendly mean of transportation. To develop it, users (both passengers and compagnies) want to have reliability and especially trains which follow timetables. If to reduce causes leading to delay or cancel a train is a difficult task, we may put some effort to minimize consequences of this problem to other tra ins. This chain effect tends to be worse and worse since the traffic is increasing while the infrastructure remains almost the same for ecomomical reasons. Train Dispatching (i.e to route train in real-time) is an important key to reduce delays and other effects in case of problems. The dispatcher chooses for each train on which track it should run and can ask a rain to stop. A typical example is the single-track connection where only in few places trains in opposite directions can meet. If the preliminary schedule is built in order to have crossing done without let some trains waiting for the other, the dispatcher should in case of an unexpected delay of one train choose either to move the crossing to another place or to stop the on-time train and keep the crossin g at the same place. When the network consists of dual or several tracks, the main problem is not the crossing but the difference in speed of different t rains (freight, long-distance passengers, suburban) and where and how a train can overtake another one.