營建工程的施工階段存在許多無可避免或不可預期的不確定因素，可能使作業施工日期延後，進而造成整體工程進度落後，因此管理者或承包商須決定趕工計畫之可行性。過往研究針對專案趕工之時間、成本為主要因素來分析趕工問題，建立時間-成本權衡模式，透過管理者輸入期望工期之情形下獲得最佳趕工決策。然而，於執行趕工計畫時，壓縮要徑作業之工期可能導致非要徑作業產生浮時損失，使專案彈性降低。本研究利用要徑指數來代表浮時損失所造成之影響，且搭配作業成本建立雙目標權衡模式並加入期望工期門檻限制，獲得兼顧成本及專案彈性之最佳趕工決策。
本研究所提出之模式分別以線性及非線性函數來描述作業成本及其要徑指數變化，試比較兩者結果之差異。此外，考量專案執行過程可能面臨許多不確定性因素進而影響工期，為避免產生模式求解結果與實際情況不相符之情形，故本研究亦提出隨機型及即時反應兩種趕工模式，將機率理論及動態排程導入模式中來處理施工期間所面臨不確定性之問題。

There are lots of inevitable or unpredictable uncertain factors that might happen during construction phase, which may cause construction progress fall behind schedule. Therefore, project managers or contractors need to set a feasible catch-up plan. To find the suitable plan, past studies focus on the two main factors, which are duration, costs, using these factors to analyze the project crashing problems. Furthermore, by entering the expected project completed time, the managers would get the optimal compression decision. However, in case of crashing, the available total float for noncritical activities may be reduced, and thus, the schedule flexibility would be reduced. Therefore, this study uses the criticality index to represent the impact of float loss, proposes a cost-criticality index trade-off model and sets the expected project completed time as a threshold to obain the decision that takes into account cost and project flexibility.
This study considers the time-cost relation via non-linear function and linear function, and compares the difference between the two results. Additionally, to correspond with the practice, this study also takes the probability theory and dynamics scheduling into account, proposing the stochastics and real-time reaction models.

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