Humanitarian OR

A two-echelon stochastic facility location model for humanitarian relief logistics

locating+ allocation
Doyen et al. (Döyen 2012) elaborate on necessity of pre- and post-disaster planning in humanitarian logistics for earthquakes. In their study, they consider a two-echelon logistics system, which facilitates the transshipment of the relief items to the demand points. In the top echelon, the relief items are stored in (uncapacitatd) regional rescue centers (RRCs) prior to the incident (e.g., an earthquake). Depending on the severity of the incident, which is realized through a set of probabilistic scenarios, the relief items are transmitted to (capacitated) local rescue centers (LRCs), where they are delivered to the demand points. Accordingly, the authors suggest a two-stage stochastic program for pre-positioning and post-distribution of the relief items. In the first stage, the location of the RRCs and their stock level is determined in pre-disaster phase. In the second stage, the decisions regarding the locations of the LRCs are made and the flows of relief items between echelons are determined. The model seeks minimization of facilities locating costs, inventory holding costs for RRCs, the necessary transportation costs, and the shortage costs. To solve this problem, the authors have developed a Lagrangian relaxation-based heuristics (LH) equipped with local search algorithm. To apply LH, the inter-relating constraints for the echelons are relaxed and lower and upper bounds are computed accordingly. Next, the solution technique performs iterative local search algorithm to improve the quality of the solution.