構建都會區運輸路網脆弱度評量模式

Constructing an Assessment Model for Metropolitan Road Network Vulnerability

臺灣地區天然災害之頻率與強度因全球氣候變遷與日俱增，造成生命財產與生活安全可觀損失。運輸系統除於防災整備階段扮演資源調度及預先疏散功能外，救災物流與孤島救援更顯其關鍵。若運輸系統失效，將直接影響當地居民移動需求，並負面衝擊疏散、醫療及救災功能。據此，本研究研擬路網脆弱度衡量模式與指標，以道路交通及社會兩構面共七項因子進行分析，藉由分析網路程序法計算指標權重，以臺北都會區為實例驗證模式可行性，利用地理資訊系統顯示圖像化結果。其中，替代路徑數量及連結性為影響脆弱度最劇之指標；而納莉風災導致路網失效則以服務水準影響最大。本研究有助於規劃者了解路網脆弱度分析架構與工具，並供決策者分析道路單元脆弱度內涵以研擬改善及資源配置策略，進行關鍵設施防護並降低災害風險。

The frequency and magnitude of natural disaster in Taiwan has increased in past years because of global climate changes, causing remarkable losses in mortality, injury as well as property. Besides resource allocation and pre-evacuation in disaster mitigation and preparedness, transportation systems also play a crucial role in emergent disaster logistics and islanding rescue. In fact, the failure of transportation system not only directly affects the transportation needs of stakeholders, but also negatively impacts the evacuation, health care and disaster relieve. Accordingly, this study explored the factors influencing transportation network vulnerability and constructed a model for assessing vulnerability according to seven vulnerability factors in two dimensions, in which the weights of indicators were determined through the Analytic Network Process (ANP). The Taipei metropolitan area was utilized as an empirical case to validate the feasibility of the proposed model. The Geographic Information System (GIS) was employed to illustrate and overlap layers for analyzing the vulnerability of each link. The analytical results revealed that the number of redundant paths and the connectivity affect the vulnerability more significantly. In the case of Typhoon Nari, the level of service was the most crucial factor leading to the failure of network. The developed method could assist planners in understanding the framework and assessment tools of transportation network vulnerability and help decision makers identify the vulnerable links and prioritize the resource allocation for protecting the critical links in a transportation network for reducing disaster risks.