First-mile logistics tackles the movement of products from retailers to a warehouse or distribution
centre. This first step towards the end customer has been pushed by large e-commerce
platforms forming extensive networks of partners and is critical for fast deliveries. First-mile
pickup requires efficient methods different from those developed for last-mile delivery, among
other reasons due to the complexity of cargo features and volume — increasing the relevance
of advanced packing methods. More importantly, the problem is essentially dynamic and the
pickup process, in which the vehicle is initially empty, is much more flexible to react to
disruptions arising when the vehicles are en route.
We model the static first-mile pickup problem as a vehicle routing problem for a heterogeneous
fleet, with time windows and three-dimensional packing constraints. Moreover, we
propose an approach to tackle the dynamic problem, in which the routes can be modified
to accommodate disruptions — new customers' demands and modified requests of known
customers that are arriving while the initially established routes are being covered. We propose
three reactive strategies for addressing the disruptions depending on the number of vehicles
available, and study their results on a newly generated benchmark for dynamic problems.
The results allow quantifying the impact of disruptions depending on the strategy used and
can help the logistics companies to define their own strategy, considering the characteristics of
their customers and products and the available fleet.