If a PT checks-out and another train is already registered (subsequent train), a decision must be made as to whether the subsequent train should also be taken into account. This decision is influenced by the minimum and maximum distance between subsequent trains parameters. If the time interval corresponds to the parameters Minimum and Maximum interval for following train, vs | plus also checks whether the frame signal for extension is still present at the cycle second of the expected arrival and the maximum green time 2 is then not exceeded. The next train is only taken into account if all conditions are met. In any case, however, a subsequent train is only taken into account if its extension conditions are not violated.