A locomotive assignment is one of the subproblems in railway
scheduling domain.
In this report present general
mathematical model of this specific subproblem and describe how
methods known from other problems domain like traveling salesman
problem, operation research and constraint programming can be used to
solve it. We concentrate especially on method known as {\it
k--interchange} for traveling salesman problem with time windows and
give an outline how it can be adopted to locomotive assignment
problem. Further, while turning from one trip to another a locomotive
must often be reallocated from one station to another. This can be
performed in two ways. A locomotive can be driven from one place to
another not performing any specific trip and exclusively using track
resource, i.e. performs so called deadhead transport, or can be
attached to any other transport and passively drown to another
station, i.e. perform so called passive transport. Because the cost of
passive transport is much lower then cost of a deadhead it is
advantageous to, if possible, replace any deadhead by passive
transport. In this report we describe a method of converting deadheads
into passive transports, describe conversion algorithm, its
implementation and report computational result of the algorithm.
Finally, we give directions for future
research in locomotive planning problem domain