Two-Phase Earthwork Optimization Model for Highway Construction

One of the main activities in highway construction is earthwork, that is a complex process involving excavation, transportation, and filling of large quantities of different earth material types. Earthwork operations are costly, and undergo several constraints due to the fact that they have large environmental and social impacts on the areas surrounding the construction site. Using mathematical models to produce a minimum-cost earthwork plan that satisfies all constraints is thus of great significance for enhancing the productivity of the overall construction project. This paper presents an earthwork optimization system based on the use of linear programming that operates in a novel two-phase approach. In the first phase an aggregate model determines the feasibility of the overall project, whereas in the second phase disaggregate models determine the actual flows of each material. The two-phase quantitative method for earthwork optimization developed in this paper includes all features derived from the everyday activity of one of the major European companies in construction. It involves classical decisions such as excavations, fillings, use of quarries and dump sites, and the temporary rent of depots, but it also accounts for several novelties, including the use of recycling facilities and the explicit integration with the existing public road network. Extensive computational results are obtained by running the models on a set of realistic instances, and show the efficiency of the proposed approach in solving complex earthwork problems.