In Lindfeldt (2009) a combinatorial model, TVEM, is developed. By varying starting
times of the different train patterns, a large set of timetables are created using a sequential
scheduler. The first steps are to schedule cyclic train services, normally passenger trains.
In the final stage, the remaining capacity is used to schedule as many train paths as
possible, normally freight trains. The quality of the train paths is controlled by limiting the scheduled waiting time. A similar approach is presented in Meng (2013) where a rolling
horizon optimization algorithm is used to measure capacity by iteratively schedule more
freight trains in a timetable with passenger trains.