مسیریابی چند دوره ای وسیله نقلیه و برنامه ریزی عوامل همراه با گزینه های برون سپاری

The planning problems confronting logistics service providers frequently involve complex decisions. Motivated by a real-life case study, this paper considers short-range weekly planning on the part of postal companies that must decide about pickup tours and delivery tours for fluctuating volume (number of shipments), with time windows for the demand points, in consideration of variable vehicle capacities and personnel planning, and including outsourcing decisions for tours and drivers. This problem can be formulated as a model of combined tour and personnel planning. However, because a real formulation of the problem involves hundreds of millions of variables and numerous constraints, in practice only heuristic solutions prove relevant. This paper proposes a hybrid metaheuristic combined with a construction heuristic that—as computer simulations have demonstrated—are suitable for practice.

2. How should postcarriage be handled? Postcarriage is the delivery of shipments that have been sorted at the depot. Certain volumes are ready at the depot for delivery at given points in time. Postcarriage then requires a decision concerning which tours are to be conducted from the depot to the demand points (e.g., post offices) and back to the depot. Again time windows must be observed for the depot and the demand points. 3. Which types of vehicle with varying capacities (e.g., tractor/trailer combinations) should be used for individual tours? 4. Which of the company's own (limited) personnel should be allocated to a tour? 5. Should leasing drivers be allocated for some tours with the company's own vehicles? 6. Should some tours be outsourced to subcontracting freight carriers, and if so, which tours? Points 1–6 above represent tour planning problems with time windows and variable vehicle capacities. Because precarriage and postcarriage must be planned for each (half) workday, a work week comprises 11 half-day planning periods (τ={1,2,3,…,11τ={1,2,3,…,11}, two for each workday and one on Saturday) with respective volumes varying from period to period. The 24-h planning period 1 starts with the tours Monday morning (tour period τ=1) with postcarriage and with precarriage tours in the afternoon (τ=2) and ends with planning period 11 with precarriage on Saturday. Thus a 24-h planning period is characterized by two tour periods (τ, τ+1). The following decisions must be made regarding alternative personnel allocation options:

Operational planning problems of transportations providers, which arise for postal service organizations and package delivery companies, lead to complex decision tasks of combined vehicle routing and personnel planning. A set of regulations must be followed for each driver, e.g., maximum duration, a break after a certain amount of driving activity. Furthermore, management must decide whether tours should be conducted by their own (limited) crew or contracted to leasing drivers or outsourced to carriers. This problem was formulated as a nonlinear mixed-integer programming model. Due to the tremendous number of variables and constraints that arise for such real problems, only heuristic solution concepts can be applied in practice. In this paper, we develop a solution framework that allows using different metaheuristics. Computational results show that especially the embedded Tabu Search procedure is very competitive for solving such real problems.