Coordinated procurement for proactive shipment consolidation in project-based production systems

Effective production planning relies on the timely coordination of upstream procurement and transportation decisions to ensure material availability while controlling operational costs. In many supply chains, decentralised procurement practices hinder shipment consolidation opportunities and lead to inefficient transportation resource utilisation. This paper proposes a proactive shipment consolidation framework supporting production planning by coordinating procurement and transportation decisions upstream. Starting from production requirements, the approach anticipates consolidation opportunities by jointly determining supplier selection, delivery timing, and truck assignments for heterogeneous orders. Unlike the predominantly reactive and carrier-driven consolidation approaches in the literature, this framework adopts a proactive buyer-driven perspective that enables coordinated procurement decisions and improves transportation efficiency while ensuring the timely supply of materials for production. The problem is formulated as a mixed-integer linear programming (MILP) model minimising purchasing, transportation, and holding costs while accounting for ongoing orders already committed to suppliers and their shipment schedules. For large-scale instances, both a matheuristic and an Iterated Local Search (ILS) are developed. Computational experiments, based on data simulating historical industrial records, demonstrate the strong managerial value of proactive consolidation and confirm its scalability for real-world deployment.