ABSTRACT
ABSTRACT Consideration of multi-hazards is essential for the maintenance management of road network. Road network would be vulnerable to disasters when maintenance and management level is low. As prevention of an extreme loss in road network performance, the problem of removal of links is mainly examined in various research and practical works. In the past natural disasters, however, most of roads suffered capacity degradation caused by partial damage. We discuss the road network performance degradation due to the large number of links suffering capacity degradation. We assumed user equilibrium state in the evaluation of network capacity. First, we conducted simulation of grid networks. The expected value of performance of the network was lowered as the more links suffered capacity reduction. The simulation also shows that tail part of the probability distribution of the network performance did not decrease monotonically. The tail consists from several phases, which are dependent on the geometry of damaged links. Such characteristics should be taken into consideration in the quantification of risk. We compared several risk quantification indices, to compare the risk of different maintenance level. We show that Conditional Value at Risk (CVaR) exhibit consistent with the level of maintenance. The phases observed in the tail part of the probability distribution exhibited different characteristics when the capacity reduction level of damaged roads is different. This indicates that the maintenance level could affect the tail risk of the network performance. To verify the applicability, the presented scheme was applied to the road network in the Shikoku Area in Japan, and obtained the results consistent with the cases of grid networks. For practical purposes, we present a scheme to evaluate the critical links. Application to Shikoku Road Network reveals that the critical links and their priority alter according to the level of capacity reduction of network, thus, maintenance level.
