Accuracy Comparison of Roadway Earthwork Computation between 3D and 2D Methods

Abstract

This study aims to calculate the earthwork volume in 3D method that has been seldom used before in roadway engineering, and to reconfirm the feasibility of average-end-area method for earthwork volume that is widely used in literature. After reviewing the related studies and comparing various CAD packages, the analysis of accuracy difference between 3D method and average-end-area method is conducted. It shows that in average-end-area method the critical value of interval distance between two consecutive cross sections is 30m. It also shows that the Change Rate of Cut-Fill (CRCF) value, an index firstly proposed to represent the cut-fill variance frequency associated with roadway terrain, alignment and profile design, has no significant impacts on the accuracy of 2D result. It is concluded that the 3D method could be easily used in practice with the CAD software. Meanwhile, average-end-area method with less than the critical interval distance between two consecutive cross sections can guarantee the earthwork calculation accuracy.