A safety-driven truck loading problem

This paper addresses a real-life multi-compartment tank-truck loading problem for fuel distribution. The proposed loading problem incorporates two safety considerations that enhance the balance of the load: i) the maximum axle weight restrictions, and ii) safety loading rules for mitigating the effects from en-route fuel oscillation. Given a route for delivering a set of orders for fuel, the proposed Truck Loading Problem aims to assign the orders to the compartments of a truck under the following load balance restrictions: i) the weight borne by each axle must not exceed certain limits at any stage of the distribution route, and ii) each compartment should be loaded either below 20% or over 80% of its capacity to mitigate fuel oscillation effects. A balanced loading of the orders at the depot does not guarantee that the load will be balanced in all subsequent segments of the delivery route. Therefore, both safety constraints must be checked in every route segment. Two MILP models are developed for the proposed loading problem covering the cases in which the compartments of the truck are equipped or not with flow meters. A major novel feature of the proposed work pertains to the development of a computational method for estimating the load weight distribution over each axle of a rigid truck with more than two axles. A series of computational experiments were performed for exploring the impact of both types of constraints on loading and route efficiency. A major finding is that using a marginal loading flexibility (i.e., deviation of the ordered quantity from the quantity delivered) diminishes any effect of the two constraints on loading efficiency.