固有値解析による固有ベクトルを利用した緊急輸送道路ネットワークの脆弱性評価  [in Japanese] ULNERABILITY ASSESSMENT OF EMERGENCY TRANSPORTATION ROAD NETWORKS BASED ON EIGENVALUE ANALYSIS  [in Japanese]

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Abstract

災害時に生じる緊急輸送を円滑に行うための緊急輸送道路が,災害時に通行可能な状態で連結できるのかどうかという連結性を高めることが重要となる.そのため,道路の被災によって連結性の観点でクリティカルな影響がある脆弱な部分を評価し,対策を施すことが望ましい.しかし,巨大災害を想定した大規模ネットワークにおいて,従来の評価方法では,膨大な数のODペアに対処する必要があるなど作業効率上の課題を抱えている.本稿では,大規模ネットワークの脆弱性評価を行うため,ネットワーク科学で研究が進められている第二最小固有ベクトルを利用する手法を提案する.さらに,第二最小固有値値・固有ベクトル中心性・媒介中心性を用いた手法を提案するとともに,それらを北陸・東海地方の様々な範囲の実ネットワークに適用し,比較・考察する.

Japan is exposed to high risks of natural disasters, such as large earthquakes, floods, debris flows or tsunamis. In case of such disasters, emergency transportation road networks (ETRNs) are expected to play important roles for quick evacuations, smooth relief supplies and so on. In order to improve the connectivity of road networks and enhance their resilience, it is necessary to detect and identify critical links of the networks in advance and take effective countermeasures. As quantitative assessment of probabilities and scales of such disasters is far difficult, one of the feasible approaches to detect fragile sections of a road network is a vulnerability assessment based on the geometry of a network. Even though, direct evaluation of the connectivities between all the nodes demands computational cost and time, especially for large-scaled road network cases due to large numbers of OD pairs, a second least eigenvalue (Fiedler vector) of Laplacian matrix of networks is proposed as an alternative in this paper. In addition, other methods, i.e., eigenvector centrality of adjacency matrix or betweenness centrality analyses are also studied. Case studies of the ETRN in the Hokuriku-Tokai region are performed and compared to discuss the applicability to road network analysis and the interpretations of results in the context of transportation engineering.<br>The proposed method shows numerical efficiency and its results are acceptable. In this study, only network geometry and a lengths of a link are considered in this study. For a future study, other features of a link, such as its capacity or specific risks based on the regular inspections of structures along it, should be included and discussed to brush up the proposed method as a practical tool.

Journal

  • Journal of Japan Society of Civil Engineers, Ser. D3 (Infrastructure Planning and Management)

    Journal of Japan Society of Civil Engineers, Ser. D3 (Infrastructure Planning and Management) 74(5), I_1141-I_1148, 2018

    Japan Society of Civil Engineers

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