Cost Minimisation in Construction Material Procurement Using Transportation Models: A Study in Lagos State

Construction material procurement in Lagos State, South West Nigeria, involves complex logistics decisions about sourcing from multiple suppliers across different locations to meet demand at various construction sites simultaneously. This study applies the transportation model, a specialised linear programming formulation, to minimise total procurement and delivery costs for a medium-scale construction firm operating across five active sites in Lekki, Ajah, Badagry, Ikorodu, and Surulere. Supply data from four quarry and depot locations in Sagamu, Epe, Agbara, and Ibeju are compiled, capturing available quantities and unit production costs. Transportation costs per tonne per kilometre are estimated using current diesel prices and truck rental rates. The northwest corner method generates an initial feasible solution, which is subsequently improved using the modified distribution method to reach optimality. Sensitivity analysis evaluates the impact of a 20 percent increase in fuel costs on optimal routing decisions and total system cost. Results demonstrate that the optimal transportation plan reduces total procurement and delivery costs by 17 percent compared to the firm's current routing practice, with savings equivalent to approximately 8.6 million naira per quarter. Three supplier-site route combinations that are currently unused are identified as cost-dominant alternatives. Keywords: transportation model, cost minimisation, construction logistics, Lagos State, MODI method.