Viaduct maintenance for future traffic demands and earthquakes

The Tokyo Metropolitan Expressway in Japan has been in operation for more than half a century. Recently, serious damages in the network have been reported in many of the old routes. However, the Metropolitan Expressway has little-to-no of experience in managing such a situation so far. Thus, developing an appropriate management strategy focusing on maintenance is critical to the expressway. The emphasis of this study is placed on the maintenance improvement of steel viaducts, and the project aims to evaluate their marginal maintenance cost and identify the influences on the cost from uncertainties such as earthquakes and future traffic demand from an econometric perspective. The study reveals that the traffic volume of passenger cars can be identified as a significant factor, while the effect of earthquake events on the cost is not clearly pronounced. Based on the analyses, it is found that the current maintenance approach is capable of dealing with fluctuations in traffic volume, which is the most influential factor. Furthermore, an increase in the amount of maintenance works could possibly lower the maintenance costs due to economies of scale. The results also indicate that the efficiency of the current maintenance method could be improved.