The contribution by List et al. [63] is mainly focused on
radioactive waste disposal. However, the authors underline that
the model is also applicable to other types of waste disposal
problems where there are specific shipper requirements to be met
in particular markets (perhaps through contracts), there is uncertainty
in the actual set of shipments that will be offered over time,
and the acquisition of equipment requires significant lead times.
List et al. [63] develop a two-stage stochastic optimization problem,
to take into account the stochasticity of some of the problem
characteristics, such as the total quantity of waste to be moved in
specific situations, or the processing rates at the sites. The problem
is modeled as a two-stage stochastic optimization problem, in
which decision variables are separated into first-stage variables,
and second-stage, or recourse variables. In this case, the truck and
package acquisition variables are the first-stage variables, because
they must be decided before values for the uncertain parameters
are revealed. The second-stage variables are represented by flow
variables for packages and trucks, which are scenario-dependent.
Another contribution of the paper is the extension of previous
work on robust optimization for fleet planning List et al. [64] to
include two distinct “risk” variables related to monetary and
“political” risk, respectively. Computational experiments show
that considering these risk terms is important in determining
the overall level of equipment acquisition.