The methodology of triage for bridges in depopulating society: modeling based on population and network connectivity

Developed countries like Germany and Japan, and many of their municipalities currently have large debts that will likely increase over time. These debts may never be repaid because debt repayment per capita will increase as a result of decreasing populations. It has become difficult for them to maintain many of their existing bridges because of large debts. Given the challenges faced with maintaining these bridges, it is necessary to formulate plans that may include discontinuing the maintenance on certain bridges. Therefore, this study proposes the use of a triage methodology for managing bridges (e.g., highway bridges) much like the triage methodology used by medical institutions to handle large numbers of patients after a severe disaster. More specifically, the proposed methodology makes decisions based on whether or not to build a new bridge after an existing bridge has reached the end of its lifespan and is decommissioned by evaluating factors such as cost and convenience. This is done by establishing a virtual network comprising of links made up of bridges that span across towns. This study proposes models and simulates this social problem by virtual networks and virtual bridge data, which can then be used to derive an optimal solution.