Economic and environmental evaluation of a brick delivery system based on multi-trip vehicle loader routing problem for small construction sites

While large construction sites have on-site loaders to handle heavy and large packages of bricks, small brick manufacturers employ a truck-mounted loader or sometimes deploy a loader truck to accompany normal brick delivery trucks to small construction sites lacking on-site loaders. It may be very challenging for small contractors to manage a sustainable delivery system that is both cost-effective and environmentally friendly. To address this issue, this paper proposes to solve a multi-trip vehicle loader routing problem by uniquely planning routes and schedules of several types of vehicles considering their synchronized operations at customer sites and multi trips. This paper also evaluates the sustainability of the developed model from both economic and environmental perspectives. Case studies based on small construction sites in the Middle East demonstrate applications of the proposed model to make the most economical plans for delivering bricks. Compared to the single-trip vehicle loader routing problem, the proposed model reduces, on average, 18.7% of the total delivery cost while increasing CO₂ emission negligibly. The economic benefit is mainly achieved by reducing the required number of vehicles. Brick plant managers can use the proposed mathematical model to plan the most cost-effective delivery schedules sustainably while minimizing negative environmental effects.