  In between transportation services, trains are parked and maintained at
shunting yards. The conflict-free routing of trains to and on these yards and
the scheduling of service and maintenance tasks is known as the train unit
shunting and service problem. Efficient use of the capacity of these yards is
becoming increasingly important, because of increasing numbers of trains
without proportional extensions of the yards. Efficiently scheduling
maintenance activities is extremely challenging: currently only heuristics
succeed in finding solutions to the integrated problem at all. Bounds are
needed to determine the quality of these heuristics, and also to support
investment decisions on increasing the yard capacity. For this, a complete
algorithm for a possibly relaxed problem model is required. We analyze the
potential of extending the model for multi-agent path finding to be used for
such a relaxation.
