**3. Earthwork optimization and planning**

Given identified quantitative and qualitative constraints, the analytical method presented in [56, 57] will be introduced for automated earthwork construction planning. This method provides an analytical approach to plan rough grading operations while making problem formulation and modeling more intuitive and simplified by the use of material flow networks. To a certain extent, it can potentially eliminate temporal-spatial conflicts (such as trucks are not allowed to haul on ungraded areas) in generation of an optimized yet more practically feasible work plan. The two-phase approach splits *earthwork optimization* and *earthwork planning* into two distinct, logically connected problems. The two problems were commonly combined in previous methods; thus representing time-dependent constraints such as temporal-spatial conflicts in field operations would result in overcomplicated mathematical models which had reduced application values of the developed models in reality.

The architecture of the two-phase approach is illustrated in **Figure 5**. At the bottom, an earthwork optimizer based on a material flow network is developed to optimize earthwork operations subject to identified quantitative and qualitative constraints. The optimization result is then taken as the primary input for ensuing analysis by the earthwork planner, which generates haul jobs, defines inter-job relationships, and produces the project network model for project scheduling and control.
