In this paper, we discuss our novel approach to support mixed-direction shunting in the planning domain for tree-like shunting yards. We explain how we used numeric fluents to improve an existing PDDL domain to support such actions. We elaborate on the underlying conceptual model of our domain and argue how does it accurately represent
shunting problems. Furthermore, we describe the experiment that we performed with the MetricFF planner to evaluate our domain and discuss the results of the experiment. Finally, we argue why the MetricFF planning system is not suitable to efficiently support our domain in real-life scenarios.