  The use of drones in logistics is gaining more and more interest, and drones
are becoming a more viable and common way of distributing parcels in an urban
environment. As a consequence, there is a flourishing production of articles in
the field of operational optimization of the combined use of trucks and drones
for fulfilling customers requests. The aim is minimizing the total time
required to service all the customers, since this has obvious economical
impacts. However in the literature there is not yet a widely recognized basic
model, and there are not well assessed sets of instances and optimal solutions
that can be considered as a benchmark to prove the effectiveness of new
solution methods. The aim of this paper is to fill this gap. On one side we
will clearly describe some of the most common components of the truck/drone
routing problems and we will define nine basic problem settings, by combining
these components. On the other side we will consider some of the instances used
by many researchers and we will provide optimal solutions for all the problem
settings previously identified. Instances and detailed solutions are then
organized into benchmarks made publicly available as validation tools for
future research methods.
