Scenario-Based Stochastic Last-Mile Pharmaceutical Delivery: MILP Formulation
9th International Symposium on Combinatorial Optimization, Aydın, Türkiye, 6 - 08 Mayıs 2026, ss.443-455, (Tam Metin Bildiri)
- Yayın Türü: Bildiri / Tam Metin Bildiri
- Doi Numarası: 10.1007/978-3-032-34519-6_31
- Basıldığı Şehir: Aydın
- Basıldığı Ülke: Türkiye
- Sayfa Sayıları: ss.443-455
- Atatürk Üniversitesi Adresli: Evet
Özet
In pharmaceutical distribution logistics, delayed deliveries can lead not only to high operational costs but also to service disruptions that may have serious health consequences. However, the assumption of deterministic travel time in current distribution operations leads to impractical or unreliable routing plans because it ignores urban density, traffic congestion, and unpredictable disruptions. To overcome this limitation, a scenario-based stochastic Capacitated Vehicle Routing Problem with Time Windows (CVRPTW) model is proposed in this study, where travel time uncertainty is represented by multiple scenarios and time window violations are integrated as penalty cost into the objective function. The model is formulated using Mixed Integer Linear Programming (MILP) that minimizes total transportation cost, fleet utilization, and expected delay penalties in all scenarios. Furthermore, a clustering-based solution approach is used to reduce the problem dimensionality and increase computational efficiency. The results obtained from this approach are given as an initial solution to the Simulated Annealing (SA) meta-heuristic. The results highlight the importance of incorporating uncertainty and penalty-based mechanisms into vehicle routing decisions in logistics operations requiring time sensitivity.