# GA-Based Optimization Method for Mobile Crane Repositioning Route Planning
## 5 Conclusions  
This study proposes RPOS, which minimizes the total operating time required for the lifting work of a mobile crane. First, RPOS converts the construction site into a mathematical model using IFC file extraction, coordinate spacing setting, reference coordinate synchronization, geotechnical attribute inputs, etc. in the BIM model. Then, RPOS identifies the feasible locations for the mobile crane by considering the physical attributes of \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Experiment** & **Grid Size (m)** & \begin{tabular}{c} **Size of Search** \\ **Spaces** \\ \end{tabular} & \
\begin{tabular}{c} **Convergence** \\ **Time (s)** \\ \end{tabular} &
\begin{tabular}{c} **Total** \\ **Operation Time (s)** \\ \end{tabular} \\ \hline
1 & 4 & 3.09878 \(\times\) 10\({}^{21}\) & 75.12 & 4326.4 \\
2 & 2 & 6.53481 \(\times\) 10\({}^{31}\) & 384.64 & 4280.1 \\
3 & 1 & 1.54221 \(\times\) 10\({}^{42}\) & 3738.91 & 4273.6 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Computational speed performance. the crane, attributes of the load, and safety regulations for lifting work. Furthermore, DA and GA-based optimization analysis methods are used to find the near-global optimal relocation route of the mobile crane. This method was developed as a MATLAB-based software, and the user can operate the system easily by inputting the aforementioned information (i.e., BIM model interlinkage, grid size, mobile crane attributes, payload attributes, and GA parameters). Furthermore, this system provides the user with visual information, such as (1) placement point sequences of the mobile crane, (2) demand point-supply point pairs, (3) travel route between the placement points of the mobile crane, and (4) total mobile crane operating time. This study provides, in detail, the computation process of the total operating time, which changes according to the placement of the mobile crane. Furthermore, the practical applicability was enhanced by suggesting a detailed mobile crane operating strategy reflecting the on-site situation. According to the results of the test case study, the near-global optimal solution search performance of RPOS is 13.7% better than that of a conventional heuristic-based mobile crane relocation search method. This study assumes that only one mobile crane is operated, and the mobile crane is limited to a common operation method, such as not moving while lifting the load. However, there are various mobile crane operation methods, such as moving while hoisting a load and collaboration between two cranes. In future studies, it is recommended to develop optimal crane operation planning methods incorporating various mobile crane operation methods. Conceptualization, methodology, and software, H.-S.G.; validation, H.-S.G. and H.-C.L. ; formal analysis, investigation, H.-S.G., B.-Y.C. and Y.M. ; writing--original draft preparation, H.-S.G.; writing--review and editing, H.-C.L. ; visualization, B.-Y.C. and Y.M. ; funding acquisition, H.-C.L. All authors have read and agreed to the published version of the manuscript. This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No. NRF-2020R1C1C1013252). Not applicable. The authors declare no conflict of interest.