Network Evaluation Based on Connectivity Reliability and Accessibility

Our daily lives and activities rely heavily on transportation systems, particularly road networks. At the same time, we face the risk of various types of natural disasters. It is, therefore, extremely important to establish road networks that are robust and reliable under conditions of network degradation caused by natural disasters. Even immediately after a disaster, an area should retain connectivity with its neighboring areas, while at the same time residents in the area should have access to adequate urban services, such as medical facilities, at a reasonable travel cost. To achieve the former goal, the concept of connectivity reliability has been developed, and to achieve the latter, accessibility measures have been proposed. This study proposes a method of evaluating road network robustness against a natural disaster by applying the concepts of connectivity reliability and accessibility. A new network evaluation measure, which considers both the risk of link disruption and the number of opportunities in an area, was first established. Then, the measure was applied to test networks, and the influence of network topology and distribution of opportunities were analyzed. Finally, the road network and medical facilities in Kyoto Prefecture were evaluated using the proposed measure.