## 3 A Construction Information Classification System for Construction Lifecycle Information
### Information Classification System for Activities  
Road construction projects involve various activities contributing to the design and construction of facilities. Figure 6 illustrates how these activities constitute a collection of unit works focused on constructing the components of the road. Each unit is further subdivided to achieve certain objectives, such as safety, quality, and process management, providing detailed information. Moreover, these activities specify the necessary resources and conditions for their execution. These activities are interconnected with the construction objects, presenting independent information that can be classified hierarchically and facetwise. They can be grouped based on similarities or hierarchically arranged by dividing or merging unit activities.  
When an activity is linked to a construction object, it modifies the attribute information of the construction object, indicating the allocation of resources and ongoing on-site construction processes. Therefore, information regarding which activities are connected to specific objects becomes a critical aspect of the construction information model, providing insights into the execution of construction projects.  
Infrastructure is managed and constructed by national or public institutions, each with its own distinct method for overseeing construction objects and activities. Consequently, the volume of construction information to be produced and managed may differ significantly.  
\begin{table}
\begin{tabular}{c c c} \hline \hline \multicolumn{2}{c}{**Object**} & \multicolumn{1}{c}{**Definition**} \\ \hline \multirow{3}{*}{Target product} & Facility & A functionally defined object that describes the target product or its parts \\  & Elementary & An object defined as a component of the target product, without functional \\  & information of the target \\ \hline \multirow{2}{*}{Auxiliary product} & Temporary & An object describing a temporary installation used to construct the target \\  & Intangible & An intangible object used to describe the procurement or construction process of the target \\ \hline \hline \end{tabular}
\end{table}
Table 1: Types of construction objects.  
Figure 6: Definition of activity (proposed).  
It is unfeasible to implement a universal regulation system for construction information models across various facilities managed by different public institutions. Therefore, an information classification system that permits flexible adjustments to be made to the construction information model is necessary.  
In principle, construction objects must be associated with one or more activities. While some objects may not be directly linked to any activity, one or more intermediate objects between the top- and bottom-level objects must have assigned activities.  
Highway construction in South Korea falls into six main categories: earthwork and drainage, bridge, pavement, apprutenant, and tunnel works. Approximately 10,733 activities were classified hierarchically. These activities can be further categorized based on their information utilization, as shown in Table 2.  
The unit construction cost is assigned to activities classified as billable, while activities of the same type but applied differently based on conditions are grouped as billable activities. These defined activities comprise multiple smaller unit activities grouped together to facilitate process management and progressive billing. Various types of construction information, including the materials, equipment, and personnel, define these activities. Time information related to the duration of unit activities can also be included. If a specific unit activity requires special management, such as safety or quality control, it was classified as an elementary activity. General management activities that could not be specifically identified in the construction process were classified as intangible.