## 3 Literature Review  
### Earthwork Scheduling  
Various studies have been conducted to achieve more efficient and accurate execution in fields related to the scheduling of earthworks in road construction. [PERSON] developed an arithmetic algorithm-based model to address the uncertainties associated with earthwork scheduling, efficient resource planning, construction site safety, and earthwork monitoring; the study supported resource planning using various options [1]. This study automated key functions related to planning based on a road project case study. However, owing to the provision of weekly plans limited to excavation schedules, it is challenging to address the overall planning of the construction site. [PERSON] et al. automated the earthwork-planning process for road construction projects to resolve complexities and efficiently support project planners by developing a model capable of time-efficient scheduling [11]. This study developed and tested a model to improve excavation planning assumptions. However, the scope of the research was limited to excavation operations. Rather than proposing scheduling results directly, it provided excavation operation data to aid scheduling. [PERSON] and [PERSON] developed an automated prototype for earthwork planning in civil engineering projects by following the principles and framework of classical planning models [12]. The prototype enables automated planning and optimization for high-level analysis, but it is limited in encompassing overall scheduling owing to the restriction of activities to excavation operations for robotic excavation. [PERSON] et al. expanded the classical linear program model for earthwork scheduling to a mixed integer linear program model for optimal planning in road construction projects [13]. This study, like the aforementioned publications, also focused on the optimization of excavation operations and thus researched a limited range of activities. [PERSON] et al. proposed a simulation approach that considered temporary road networks for efficient earthmoving operations that led to cost reduction and time savings [14]. However, in this study, the algorithm was applied to seven activities that corresponded to excavation and transportation operations, suggesting that the level of detail may be somewhat insufficient for practical applications in the field. [PERSON] and [PERSON] proposed a discrete-event simulation and object-oriented simulation engine for modeling earthmoving operations and provided tools for estimating time and cost [15]. Given that this study was limited to equipment combinations in excavation operations, it only considered a small number of activities for scheduling throughout the entire earthwork project, thus highlighting its limitation in focusing on a few specific pieces of equipment.  
Previous studies related to earthwork scheduling were mostly limited to excavation tasks, which constitutes a major limitation. While research focusing on excavation tasks within earthwork is reasonable given its crucial importance, the lack of studies addressing earthwork scheduling is evident. Considering that most studies have been conducted based on a few activities, the scarcity of research on earthwork scheduling at a comprehensive level introduces a major research gap. Studies considering activities at a detailed level are essential for the overall successful execution of construction projects.