Haulage sharing approach to achieve sustainability in material purchasing: New method and numerical applications

Transportation costs are becoming increasingly important in inventory replenishment decisions and, in practice, lot sizing decisions are strongly affected by material handling equipment, transportation flow paths, vehicle capacities and technical constraints. Companies within a global sourcing context daily experience the cost of transportation as playing a major role in total purchasing costs. On the other hand, sustainability issues are always more urgent and environmental impact assessment is becoming a key requirement for materials purchasing and transportation choices. This work is particularly focusing on an interesting new area of research: the haulage-sharing in freight transportation when sustainability considerations are taken into account. The paper develops and discusses a new haulage-sharing lot sizing model in which two partners are cooperating in sharing transportation paths and handling units. A three step methodology based on multi-objective optimization approach is here proposed to permit the complete evaluation of the costs and savings that arise with an horizontal cooperation. The method is described here and applied to two different numerical cases in order to drive useful conclusions and discuss future research steps.