2.3. Summary of Past Literature. Although routing models
in STD networks are gaining greater attention in the literature
and industry, a general modeling framework and
efficient solution algorithm which is applicable to large-scale
real-world networks are still lacking. Stochastic and timedependent
travel times are more extensively operated on optimal
path analysis between two service nodes when executing
VRP delivery. However, most of the existing approaches to
the STDOPP generally need a precise probability distribution
of the uncertain link travel times which is hard to realize
in practical application. High computation complexity and
inefficient algorithms are also strong restraints when solving
large size networks problems. In recent years, robust
optimization theory has emerged as a preemptive way to
address the uncertainties of link travel times with better
computational tractability, meanwhile without requiring the
precise probability distribution of link travel times.
In this paper, for such delivery routing with rigid arrival
time requirements, the worst-case travel times of each candidate
path connecting any pair of customer nodes should be
considered to guarantee the time window constraint satisfied.
Beyond that, the reliability of travel time is also a concern in
delivery. So we refer to the robust approach here and apply