都會區公路路網脆弱度之評量模式

Abstract

近年來，全球氣候變遷使得各地容易出現極端型的氣候型態，而台灣地區的天然災害發生次數亦日益頻繁，對於生命、財產與生活安全皆造成不少的損失，同時對於運輸系統亦會產生毀壞致使道路功能失效。然而，道路系統的功能若是因毀壞而失效不僅會直接影響當地居民的不便，且避難、醫療及救災的功效亦會受到影響，因此路網的整體效能是相當重要的。若是能針對相對比較脆弱的地點優先進行防範措施使其避免受到危害衝擊，如此便能降低損失，達到預防的功效。脆弱度分析的重要目標係協助決策者瞭解現狀，並據以執行災害的預防及整備等防護策略以降低災害風險，因此高脆弱度的地區應該具有較高的防護優先性。 首先，本研究透過文獻評析以確認研究探討的重點，並且同時分析影響路網脆弱度的因素，進而擬定評估模式的衡量指標。根據建構的路網脆弱度評估模式，影響因素可分為兩個面向：道路交通面與社會面，共計有七個衡量指標。再者，衡量指標權重係透過分析網路程序法（ANP）加以計算，其指標與權重分析結果如下：最短路徑延滯時間（0.37）、服務水準影響數值（0.25）、替代道路數量（0.23）、連線指數（0.15）、潛在影響人口數（0.41）、依賴人口比例（0.42）及身心障礙人口比例（0.17）。其中，前四者為道路交通面向，而後三者為社會面向。 路網脆弱度評估模式建構完成後，進行台北市都會區路網脆弱度的計算，並利用納莉颱風災情作為案例分析，其分析結果如后。因納莉颱風而對路網造成的影響相當明顯，其致使整體路網的失效比例約14.24%，而影響失效比例的主要指標為「替代道路數量」、「連線指數」及「最短路徑延滯時間」。此外，若藉由路段脆弱度的角度而言，路段屬於高脆弱度等級的比例由33.4%上升至48.4%，而屬於低脆弱度的路段比例由31.7%降為26.7%。若僅以道路交通脆弱度來看，高脆弱度等級的比例則由30.0%轉為高達91.7%。

Recently, global climate change results in extreme weather patterns in various regions. There are increasingly natural disasters in Taiwan; it surely results in many damages concerning life, property and life security. Moreover, natural disasters not only lead to transport system out of order but also road system function. Besides, road system function out of order not only directly influences locals but also the efficiency of refuge, medical treatment and aid. Therefore, the entire efficiency of road network is very important. If we have priority in relative weak place to take precautions against damage impact, then it can reduce losses and achieve prevention efficiency. The important purpose of Vulnerability analysis is to help decision makers understand the current situation; they enforce disaster prevention policies and protection strategy to reduce disaster’s risk. To sum up the high vulnerability region should have a high protection priority. First, this study is through the literature assessment to confirm the focus of research and then it analyzes the factors which make the road network vulnerable and creates indicators of the assessment model. According to the construction of the assessment model of road network vulnerability, the impact factor is divided into two dimensions: traffic and social, with a total of seven indicators. Moreover, the weight of indicators is estimated through Analytic Network Process. The indicators and the weight results are as follows: the time delay of shortest path（0.37）, impact value for Level of Service（0.25）, number of alternative route（0.23）, γ index（0.15）, the potential impact of population（0.41）, Dependent Age Population ratio（0.42）, and disabled population ratio（0.17）. The fist four belong to the traffic dimension and the others belong to the social dimension. After the construction of the assessment model of road network vulnerability is completed, it estimates the road network vulnerability in Taipei metropolitan area and analyzes the effects of Typhoon Nari. This analysis gives the following results. Typhoon Nari’s impact on the road network is fairly obvious. The failure rate of the entire network caused by the typhoon is about 14.24%. The main indicators which influence the rate are ‘number of alternative route’, ‘γ index’, and ‘the time delay of shortest path’. In addition, from the perspective of link vulnerability, the ratio of high vulnerability level sections increases from 33.4% to 48.4%, and low vulnerability level sections decreases from 31.7% to 26.7%. But if only from the perspective of the road traffic vulnerability, the ratio of high vulnerability level sections highly increases from 30.0% to 91.7%.