# A Typology Model of Temporary Facility Constraints for Automated Construction Site Layout Planning
## 5 Validation  
The goal of this paper was to gather and classify constraints that are actually considered during the layout of the target temporary facilities for use in computational modeling of construction site layout planning. Therefore, as a validation study, three characteristics (i.e., clarity, substantiality, and comprehensiveness) of the CSLP constraints model were tested based on four actual CSLP cases with various uses and sizes (Table 7). Substantiality was tested through a comparison between the constraints actually considered in the cases and the constraints identified in this study. Clarity and comprehensiveness were tested through interviews with experts who participated in the cases. All experts had more than ten years of experience in the field of construction and had participated in more than two construction projects. Moreover, when temporary facilities are automatically laid out using a computer, construction site layout that cannot be applied in reality may be generated if the temporary facilities are located outside the site or overlap with other objects. To prevent this from occurring, the constraints RG1 and NO1, which must be included in CSLP, were omitted in the validation study. First, the clarity of each constraint was measured by the experts who actually performed the surveyed CSLP projects. The clarity was evaluated on a 5-point Likert scale, and all constraints were found to obtain an average of 4.85 points (minimum: 4; maximum: 5; standard deviation: 0.27). This suggests that all identified constraints can be clearly understood by the construction site layout planners, and there will be little difficulty in transcribing the constraints in a computer-interpretable form. \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **Case 1** & **Case 2** & **Case 3** & **Case 4** \\ \hline \multirow{3}{*}{Use} & Apartment & Apartment-style & Residential- & Commercial \\  & (residential) & factory & complex & facilities \\ \hline Construction & \multirow{2}{*}{USD 223M} & \multirow{2}{*}{USD 160M} & \multirow{2}{*}{USD 144M} & \multirow{2}{*}{USD 122M} \\ cost & & & & \\ \hline Site area & 56,863 m\({}^{2}\) & 33,000 m\({}^{2}\) & 19,196 m\({}^{2}\) & 14,997 m\({}^{2}\) \\ \hline Buildings & 9 buildings & 1 building & 4 buildings & 2 buildings \\ \hline Structure & RC & PC + RC & RC & RC \\ \hline Stories & 37 & 13 & 40 & 33 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Project profiles used in validation study. Figure 8: Checking visibility constraints: raycasting approach (**a**) and sight query algorithm (**b**). Second, the substantiality of constraints was measured by asking whether each constraint was actually considered in multiple CSLP cases. Experts were asked to choose between O (considered at the site), \(\bigtriangleup\) (not considered at the site but worth considering), and X (never considered and not worth considering) for each constraint. When they thought some constraints were outside their expertise, they were asked to mark the constraints \"NR\" (not responded). The evaluation found that all constraints identified in this study could be considered O or \(\bigtriangleup\) in at least three CSLP cases. The finding means that the constraints identified in this study are substantial enough to be generally applied in CSLP of actual construction projects. However, depending on the project characteristics, there may be differences in the constraints considered by the planners. For example, regarding the IF8 constraints, it was confirmed that whether or not the tower crane can invade the road may depend on the level of permission of the administrative district. As another example, for VI2, it would be considered optimal if the office's location is located where the site could be viewed as a whole, but if it is difficult due to the site conditions, there is also a possibility of using CCTV to solve this. These examples imply that these constraints are generally necessary, but sometimes it can be used as soft constraints depending on the nature of the construction projects.