# Evaluation of Bridge Maintenance Priorities in Megacities
## 4 Application of the Proposed Model to Eight Megacity Bridges
### Analysis of Maintenance Priorities of Bridges in Megacities  
As shown in Table 7, the result of the BMP score data analysis, the risk score of the bridge was most affected by age. Age has the greatest impact on the risk score, through the safety grade, and is the most important factor. This is because regular inspections and safety diagnoses are carried out based on the safety grade. In the case of low safety grades, the safety grade of the bridge is raised to a safe level by performing immediate maintenance, resulting in a small deviation of safety grade for each bridge. In the risk score, the effect of design load was found to be the smallest because most of the bridges in Megacity were designed with DB-24, giving the same score. The H bridge had the highest risk score of 4.4; at the same time, the BMP score was 2.29, which was the sixth-highest  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{
\begin{tabular}{c} **Bridge** \\ **Name** \\ \end{tabular} } & \multicolumn{3}{c}{**Risk**} & \multicolumn{3}{c}{**Criticality**} & \multicolumn{3}{c}{**Comparison**} \\  & & **Score** & & & **Score** & & **Score** & & **Score** \\ \cline{2-10}  & **Age** & **Design** & **Seismic Design** & **Safety** & **Total** & **ADT \({}^{*}\)** & **Facility** & **Number of** \\  & & **Load** & **Status** & **Grade** & **Total** & **ADT \({}^{*}\)** & **Classification** & **Lanes** & \\ \hline A & 0.5 & 0.1 & 0.1 & 0.3 & 3.0 & 0.8 & 1.0 & 0.8 & 4.32 \\ B & 0.7 & 0.1 & 0.1 & 0.3 & 3.6 & 0.8 & 0.7 & 0.6 & 3.74 \\ C & 0.5 & 0.1 & 0.5 & 0.3 & 3.8 & 0.8 & 1.0 & 0.4 & 4.26 \\ D & 0.7 & 0.1 & 0.1 & 0.3 & 3.6 & 0.6 & 0.7 & 0.4 & 2.38 \\ E & 0.5 & 0.1 & 0.1 & 0.5 & 3.8 & 0.6 & 1.0 & 0.6 & 3.65 \\ F & 0.3 & 0.1 & 0.1 & 0.3 & 2.4 & 0.6 & 1.0 & 0.4 & 2.02 \\ G & 0.5 & 0.1 & 0.5 & 0.3 & 3.8 & 0.4 & 0.7 & 0.4 & 1.67 \\ H & 0.7 & 0.1 & 0.5 & 0.3 & 4.4 & 0.4 & 0.7 & 0.6 & 2.29 \\ \hline \hline \end{tabular} \({}^{*}\) ADT: Average daily traffic.  
\end{table}
Table 7: Maintenance priority selection results.  
Figure 5: Distribution by factors according to BMP score results.  
number among the eight bridges. Bridge A, which had the highest BMP score of 4.32 and the lowest risk score of 3.0 among eight bridges, except for Bridge F, had the highest BMP score and the lowest risk score. This is because Critically Score and Comparison Score were the highest among the eight bridges.  
The results of this study are different from the case of considering only the stability level that determines the existing maintenance priority. It is judged that the model developed in this study reflects the influence and importance of bridges well. As shown in Figure 5, the BMP score is not calculated by only one of the three factors. A combination of factors is used to calculate the BMP score, not just one of these factors. However, as shown in Figure 6, It can be seen that when the BMP score is ranked in ascending order, the tendency is similar to that of the Criticality score and Comparison Score. This is because the factors constituting Criticality Score and Comparison Score have social values. As such, the maintenance priority of the bridge should reflect not only the safety level of the bridge but also the social value of the bridge. The combined factors of the model proposed in this study can help determine the maintenance priority of the Megacity bridge, and further accuracy can be achieved by applying adding factors related to the life and influence of the bridge.