Method for Optimizing Earthwork Considering Soil Properties in the Geometric Design of Highways

Economic considerations are one of the most fundamental elements affecting the standards of highway projects. Therefore, cut-fill balancing and minimizing the amount of earthwork are significant factors that can decrease construction costs. In order to achieve this, the “weighted ground line method,” which describes a hypothetical ground line that guides cut-fill balancing and minimizes the total amount of earthwork, is presented. The main idea of this approach is to find a “hypothetical reference line” (instead of a ground line) that makes the earthwork optimization possible in terms of cut-fill balancing as well as earthwork minimization. Because the centerline ground elevation rarely represents the transverse changes in the ground elevations of a cross section (template), setting the grade line as close as possible to the ground line may be misleading in terms of optimizing earthwork. Another point to be considered is that all the excavated (cut) material may not be used as a fill material due to the difference between the original volume in a cut and the volume in a fill after compaction. Furthermore, all excavated material may not be suitable for fill. In this respect, to be able to accomplish the exact cut-fill balance and minimize the total amount of earthwork, these two factors must be taken into consideration. For this reason, modified cut and fill volumes should be used for calculating weighted ground elevations. Consequently, the aim of this paper is to balance the cut-fill volume and minimize the amount of earthwork while considering shrinkage and swell factors, thereby achieving much more cost-effective results.