公路橋樑建造工期之研究-以支撐先進工法為例

Abstract

隨著國內經濟持續發展加上國人對環境景觀的要求，公路橋樑建造數 量及規模日益增加，而橋樑建造工期不僅為工程審議及執行機關所關心， 亦為承包商控制成本之重要因素，實有必要建立一簡便可行的工期估算模 式，因此，本研究乃以審議機關之觀點，針對橋樑工期進行研究與探討。 本研究將工期推估之方法區分為三類，包括排程技術推估方法、經驗推估 方法及統計計量方法。排程技術推估方法屬微觀之工期估算方法，為承包 商與工程執行機關訂定工期之依據，但往往有個別性太強而難以一般化之 缺點，對審議機關而言並不易於應用。經驗推估方法則屬於巨觀之工期推 估方式，是工程機關及審議機關長久以來倚重之方法，但專業人力之訓練 及經驗累積不易。而統計計量的方法，則是藉由科學的方法將專業人員的 經驗與智慧加以歸納整理，在面對遽然增加之工程建造規模，應是可行的 方式。 由於橋樑工期受工法之影響顯著，本研究受限於研究時間及資 料，乃針對支撐先進工法進行工期研究，將影響工期之因素歸納為確定性 因素及不確定性因素二類，同時參考國外預估工期之時間成本模式，以多 元迴歸方程式構建橋樑工期推估模式。模式經過檢定及殘差分析，配適度 佳。然由於目前支撐先進工法橋樑在國內完工之案例並不多，較為完整者 多為設計發包之工期資料，因此，本研究另就橋樑上部結構之施工時間蒐 集三個案例，進行分析比較，最後對研究結果與未來發展做成結論與建議 ，以供工程審議機關參考。 As rapid economic growth continues and the requirement of landscape is stronger,the quantity and scale of highway bridges are more considerable. Therefore,the problem of estimating the construction duration of bridges is a great concern not only for the government agencies, but also for the contractors. The duration is an important factor for budget control. It is necessary to develop a reliable and fast method for estimating duration of bridge construction. In this research, we study this duration problem from the viewpoint of the engineering reviewers. There are three categories for duration estimation: scheduling technique, expert-estimating, and statistic method. Scheduling technique is a micro method for contractors to deal with contracts, but it is usually designed for individual project and the engineering project reviewers could not easily use this technique in a general way. Expert- estimating is a macro method that the government engeering bureaus have depended on it for a long time, but experienced duration estimators are rare and very domain-specific. It is reasonable to use statistical skill, a meso method, to develop a duration estimating model. Each construction method has its own procedure that affects the duration of bridges evidently, this study just focuses on one method, that is the Advancing Shoring Method(ASM), for limited time and data resources. We divide the factors,affecting the duration, into two categories: deterministic factors and non-deterministic factors. After reviewing the time-cost model, we employ a multiple-regression model to estimat the construction duration of bridges. It is shown from the coefficient testing and the residual analysis that the fitness of the model is pretty well. Since there are few bridges have been constructed with ASM in Taiwan, we analyze the difference between design stage and construction stage on estimating the duration of superstructure of bridges for reference. Finally, we make concludions and recommendations for future work.