運輸系統是人類生活不可或缺的重要命脈，在運輸系統中又以公路系統為重要的一部份。然而，公路路網系統往往因為天然災害造成損壞，使得公路路段無法正常運作，路網之連通性也跟著受到影響。是故，如何對公路路網系統事先進行防災以及預防措施避免災後造成嚴重破壞便成了重要的課題。此外，在進行災前預先防護的計畫上，若能發展一套利用路網系統可靠度為評估指標之模型，其路段保護決策將能夠讓決策者在進行路網保護計畫時有合適的參考依據，並進一步提升保護決策之正確性。 本研究將探討若天然災害發生前能對某些路段進行保護，避免災害來臨時造成路段的阻斷，以維持整體公路路網系統的連通性。由於天然災害造成公路路網系統的損壞通常是隨機性的且難以預測，再進行路段保護決策時有一定的難度。因此本研究發展出以路網系統可靠度為最佳化目標之隨機規劃數學模式，研究中利用路網OD起迄對連通總數期望值為基礎，定義不同連通可靠度指標，在隨機災害情境中進行路段保護之決策，比較不同可靠度為目標之決策並進一步分析其決策之結果。 研究中先以虛擬路網測試隨機規劃模式對於路段保護決策之正確性，接著以苗栗地區公路橋梁系統進行實際案例之應用，利用台灣地震損失評估系統(TELES)模擬地震災害所造成公路橋梁損壞之情境進行分析。案例分析的結果顯示本研究所建構之隨機規劃模式能夠有效的改善公路路網連通可靠度。本研究所發展出之隨機規劃模型能夠根據不同路段保護預算限制下做出對整體最佳的路段保護決策，在預算緊縮之情況下也能夠做出對大部分災害情境最有利的路段保護決策，使得絕大部分之災害情境能夠有最大的連通可靠度。此模式能夠有效的提供決策者在進行路網保護計畫時的參考依據，進一步提升路段保護決策之正確性。 ;A country’s transportation system is indispensible because it has a direct impact on the economic development and the quality of people’s life. Highway system is one of the most important systems in transportation. However, a highway network is subject to natural disasters. When highway links lose functionality due to a disaster, the connectivity of the network could be affected, that is, some or all of the travel demand cannot be satisfied. In addition, it is beneficial to improve the performance of highway network system and protect against natural disasters if we develop a decision-making processes for protecting highway network system in advance. In this study, we consider a situation where some links of the network can be protected against the disaster to maintain the connectivity of the network. Because the damage to a highway network caused by a disaster is probabilistic, making protection decisions is difficult. In this study, the connectivity reliability has been introduced as a performance measure. We develop a stochastic programming model to find the optimal protection strategy for a highway network system that maximizes connectivity reliability. Based on the expected number of origin-destination (OD) pairs that can be served under all scenarios of link failure due to a disaster, we also define three different indicators of connectivity reliability of a network.They can be used to evaluate protection strategies for a highway network subject to disasters. The proposed model is demonstrated with the highway bridge systems of Miaoli City. The natural disasters we consider are earthquakes that were simulation by the Taiwan Earthquake Loss Estimation System (TELES). The results show that the proposed model has potential for improving highway network connectivity reliability.
