| Abstract: |
Determining the optimal number and location of intermodal transshipment
terminals is a decision that strongly influences the viability of the
intermodal transportation alternative. In this paper, we develop a model and
an optimization method that provides policy makers with a tool to help them
take these decisions. The objective of the terminal location problem described
in this paper is to determine which of a set of potential terminal locations
to use and which not and how to route the supply and demand of a set of
customers (representing zones of supply and demand) through the network (by
both uni- and intermodal transport) so as to minimize the total cost. We
develop two different metaheuristic procedures that both consist of two
phases: a solution construction phase and a solution improvement phase. The
first metaheuristic constructs solutions using a GRASP procedure, the second
one uses the relatively unknown attribute based hill climber (ABHC) heuristic.
Innovative in our approach is the integration of a fast heuristic procedure to
approximate the total cost given the set of open terminals. Both
metaheuristics are compared to the results of an MIP solver. A thorough
performance assessment uncovers that both metaheuristics generate
close-to-optimal solutions in very short computing times. An argument in favor
of the ABHC approach is that it is parameter-free and hence more transparent
and likely to be accepted in a business or policy environment. |