# Evaluation of Bridge Maintenance Priorities in Megacities
## 5 Conclusions  
Some countries, such as Korea, face serious consequences from the increasing number of aging major bridge structures. Ad hoc maintenance and repair can be costly and not always well-targeted. It is important to have an effective and efficient maintenance system in place. Instead of simply determining risk according to a bridge's structural details and comparing the maintenance order (as is often done), a maintenance priority selection model for megacity bridges was proposed based on the qualitative risk, importance, and comparison score drawn from a dataset of actual bridges. In the case of selecting the existing maintenance priority, maintenance is performed on bridges with low safety grades based on national standards. This approach is a result of the lack of consideration of the social value and importance of bridges. In the proposed bridge maintenance priority model, not only the risk score but also the criticality score were used to reflect the social value and importance of the bridge. This can be exemplified by the values of Bridge A and Bridge H in Table 7 Maintenance priority selection results. In the case of bridge A, the risk score was 3.0, and it had the second lowest value among the eight bridges but had the highest  
Figure 6: Results by maintenance priority. BMP score. In addition, the H bridge had the highest risk score of 4.4 but showed the sixth-highest BMP score. In the proposed maintenance priority model of bridges, bridge social value and importance were reflected by using not only risk scores but also importance scores. Therefore, it can be judged that it is possible to select the bridge maintenance ranking that is required by broader society rather than purely bridge maintenance ranking according to existing safety grades. The model proposed in this study uses only data provided by national institutions and local governments and takes a total of three scores (risk score, importance score, and comparison score) so that a total of seven factors constituting each score can be applied. Further research is needed on additional factors that can represent risks in bridges other than the seven factors used to determine the maintenance priority of a proposed bridge. For example, it is necessary to add the effects caused by the closure of the bridge during maintenance and the presence or absence of other facilities on the upper and lower parts of the bridge. This is a limitation that occurs because the factors of the model developed in this study use only data that can be utilized by national institutions and local governments, and it is judged that these problems should be recognized and improved by the national and local governments. In addition, since there is no consideration for hazards that act as an absolute factor in the stability of bridges, there is a need to consider factors for hazards in the future. Due to the fact that the model in this present work uses relative criteria for prioritization, it can be more efficiently used as a decision-making model when combined with conventional prioritization methods rather than just using it independently. This is because the proposed model has a problem in that it is impossible to evaluate each bridge compared to previous studies based on probabilistic methods and neural networks, and the accuracy of the evaluation may be reduced. However, the number of bridges that the bridge management entity is in charge of is very large, and there are difficult problems in accessing a significant number of bridges in a sophisticated manner. Therefore, it is judged that the reliability and accuracy of the proposed model should be improved through continuous research, and through the improvement of the proposed model, the bridge management entity will be able to reasonably and simply determine the priority of bridge maintenance. In addition, it is emphasized once again that the purpose of this study is not to evaluate the stability of bridges but to help determine the priorities for performing bridge maintenance. Conceptualization, J.L., S.C., J.-M.Y.