Planning Problems in Intermodal Freight Transport ...

traffic conversion method and a freight flow consolidation method. First, freight flows are
converted from tonnes to numbers of load-units. Second, freight volumes are assigned to
routes and consolidated with the objective to find terminal locations that will attract sufficient
freight to run daily trains to and from the terminal. The model is applied to the design of an
inland road and rail terminal network in the Netherlands. Racunica and Wynter [29] discuss
the optimal location of intermodal hubs in a hub-and-spoke network with (semi-) dedicated
freight rail lines. The problem is formulated as a frequency service network design model
with frequencies of service as derived output. A concave cost function is applied in order to
capture cost reductions obtained by consolidation at hub nodes. The resulting model is a non-
linear, mixed-integer program. Next, the concave increasing cost terms are approximated by a
piecewise linear function in order to obtain a linear program. This linear program is solved by
two variable-reduction heuristics, which solve a sequence of relaxed subproblems. Finally the
solution method is tested on a case study of the Alpine freight network.
Second, simulation may be used to define terminal locations. Meinert et al. [30]
investigate the location of a new rail terminal in a specific region in which three rail terminals
are already located. The authors specifically consider the impact of the location of the new
terminal on drayage length and time. In order to accomplish this, a discrete event simulation
tool is developed which provides the ability to address individual rail terminal design
considerations such as handling capacity required, regional design considerations related to
terminal location and trucking distances, and demand distribution over time. A significant
feature of this simulator is that, rather than modelling only the operation of the terminal, it
also models the drayage to and from regional destinations.