Highly reliable traffic networks on highways and roadways are very important during abnormal periods, such as during disasters. Network reliability can be improved effectively by focusing on the most important key link in the network. Although many indices have been proposed for identifying the most important key link, numerous shortcomings associated with these indices make it difficult to obtain a good solution for evaluating network reliability improvement. In addition, an investment strategy based on local government support is also important for improving network reliability. However, the capital available from local government for traffic restoration is usually limited after a disaster. This paper therefore proposes an optimal method of network reliability improvement based on local government support combined with limited capital. To determine the efficiency of the model for network reliability improvement, simulations for a simple parallel network and a simple bridge network are conducted. A general algorithm for identifying the most important key link in any network is then developed based on these simulations. Lastly, a rational conclusion for network reliability improvement is presented.

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  The 2011 Great East Japan Earthquake forced a reevaluation of the effectiveness of disaster management facilities and strategies in coastal communities where damage due to an earthquake and resulting tsunami from the Nankai Trough can be expected. Specific areas subject to reevaluation include (i) individual-level topics in disaster risk management, such as the use of motor vehicles for evacuation, (ii) challenges initiated by government reappraisals of tsunami estimation, such as the safety of existing shelters, and (iii) low tsunami evacuation rates in areas at high risk of tsunami damage, despite evacuation orders issued at the time of the Great East Japan Earthquake. This study discusses the impact of these factors on the consciousness of residents in a community where we performed action research. The results of a questionnaire survey indicate that Okitsu residents have similar problems regarding tsunami evacuation as those revealed in the devastated areas of the Tohoku region. To promote disaster consciousness and improve tsunami evacuation rates, we suggest a new approach to evacuation drills called the single-person drill. This drill changes a community practice into an individual activity that we hope will involve more residents in disaster risk management, and ultimately contribute to their successful tsunami evacuation.

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