地震後橋梁及其鄰近區域損壞所產生之社會成本試算模型建立﹣以中正橋為例

臺灣本島位處兩板塊交界，地震災害頻繁，因地震所造成的大規模破壞不僅對局部區域帶來衝擊，亦會對整體經濟構成嚴重威脅。而橋梁做為都會區重要的交通樞紐，當橋梁因地震損壞時，除了直接的維修、重建成本外，間接社會成本也隨之衍生。本研究回顧文獻後發現，歷史研究大多著重於前者的估算，對於社會成本方面仍缺乏可靠的評估方式，所導致之無形鉅額損失有時甚至會超越直接成本，影響不容小覷。本研究參考「橋梁服務功能性」，考量橋梁及其鄰近區域因地震所造成的損壞情況，確立四大社會成本影響因子：交通成本、人命傷亡成本、維生管線成本與經濟損失成本，針對各項成本進行分析及資料搜集，進一步研擬量化估算的流程與步驟，並完成試算模型的建立。模型建立完成後，本研究將以有近五十年歷史的中正橋為例，假設若中正橋遭受地震毀壞而部份或全部無法通行時，分析橋梁用路人及其鄰近區域受到的衝擊影響。首先，利用Google Map分析行車路徑，將數據整理代入本研究模型中以求得各項交通成本，並分析繞道與交通事故間的關係。其後，藉由TELES系統模擬地震造成的破壞情形，將不同損壞程度之樓地板面積導入本研究模型中，計算鄰近區域因建物損壞所帶來的經濟損失。俟所有社會成本量化完成後，整理出各項影響因子，並比較分析因子間的相對關係。最後，本研究將前述試算流程建立成一標準作業程序（SOP），並針對各項社會成本涵蓋範圍進行說明，詳述其計算流程與步驟。使政府機關可參考本研究所示範之案例，實際將不同橋梁的數據代入本研究模型中演算，分析橋梁損壞後所衍生的各項成本，藉以評估各橋梁的重要性，進而做為擬訂橋梁維修補強優先順序的參考依據，使資源能達到最有效的運用。

關鍵字

社會成本；橋梁損壞；財務模型； TELES ；中正橋

並列摘要

Taiwan is a country with a lot of earthquakes. The massive destruction caused by the earthquakes not only affects the surrounding area but also threats the economic formation of the society. As a transport hub, bridge is significant especially in metropolitan area. When damaged by earthquakes, it usually causes a variety of direct and indirect costs. However, most studies focused on the estimation of direct costs, the methodology of assessing social cost is seldom mentioned. The huge losses caused by the social cost may exceed the direct cost, thus the impact of social cost should not be ignored. This research establishes the impact factors of social cost based on the method of bridge classification. By analyzing and data-collecting, this study develops the procedures to quantifying the costs of all factors and then builds a calculation model. After that, the case study of Zhong Zheng Bridge is conducted to evaluate the influence on surrounding areas caused by earthquakes. First we can get the route information by Google maps and use the data to calculate the costs of transportation. Then by employing the TELES system, we can simulate the earthquake damage and calculate the financial losses of the adjacent area. Finally, this study proposes a SOP of the calculation process and explains the detailed steps. Moreover, the government could refer to the model and the case study result to assess the importance of each bridge and then to decide the mending priority.