Earthquakes are sudden, unpredictable disasters that disrupt transportation infrastructure while generating surges in medical demand, posing critical challenges to last-mile pharmaceutical logistics. Existing humanitarian logistics models rarely integrate heterogeneous transportation modes, time-dependent mode switching, and operational constraints within a unified framework. This study develops a cost-optimised pharmaceutical distribution model based on a heterogeneous vehicle routing problem (VRP) that incorporates post-disaster infrastructure disruption, time-based mode switching, and overtime penalties. Using the 2022 Cianjur Earthquake (Indonesia) as a case study, three strategies are evaluated: a baseline, a Mixed-Integer Linear Programming (MILP) optimisation model, and a two-phase heuristic combining a savings algorithm with local search. The model distributes 550 pharmaceutical packages to 47 primary healthcare centres (PHCs) under a 480-minute daily operating constraint. The MILP model reduces total cost by 5.89% relative to the baseline (IDR 430,052,945), while the two-phase heuristic achieves the lowest cost (IDR 391,811,960; ?8.89%) at a 100% service level. Sensitivity analysis indicates a four-day emergency duration gives the most cost-efficient transition from fast-response modes to consolidated truck distribution. The findings provide a practical optimisation framework and decision-support insights for efficiency, responsiveness, and resilience in disaster pharmaceutical logistics.

Keywords:

Pharmaceutical logistics, Disaster preparedness, cost efficiency, heuristic algorithm, vehicle routing problem

@article{oscm-2026-1231,
  title={A Humanitarian Logistics Model Integrating Heterogeneous Vehicle Routing, Time-Based Transportation Mode Switching, and Overtime Penalties for Disaster Pharmaceutical Logistics},
  year={2026},
  author={Lingga Ikaditya and Yosi Agustina Hidayat and Zulfan Zazuli and I Ketut Adnyana and Zulfian Muhammad Furqon},
  journal={Operations and Supply Chain Management: An International Journal},
  volume={19},
  number={4},
  pages={640--656},
  doi={10.31387/oscm0670543}
}

Lingga Ikaditya, Yosi Agustina Hidayat, Zulfan Zazuli, I Ketut Adnyana, Zulfian Muhammad Furqon (2026). A Humanitarian Logistics Model Integrating Heterogeneous Vehicle Routing, Time-Based Transportation Mode Switching, and Overtime Penalties for Disaster Pharmaceutical Logistics. Operations and Supply Chain Management: An International Journal, 19(4), 640-656. https://doi.org/10.31387/oscm0670543