工程設施於喪失或降低機能時，須進行維護作業以恢復或增強其設計之功能。以公共工程而言，由於設施種類相當繁多，完工年限與使用情況不一，故設施損壞須維修時，常有構件種類繁雜、數量不確定之特性。而當公共工程進行維護時，須透過政府採購法之採購程序發包施作，每次維護作業均需耗費相當人力與時間，常造成維護執行單位之困擾。 近年來，公路工程在進行維護工作發包時，為減少合約件數與簡化作業流程，多採用開口合約方式進行設施之維護。所謂開口合約，為機關與廠商訂定之採購契約，其特性在於維護工作之數量不確定，工作執行之時間亦不固定，須待機關提出維護需求時再執行；其施作期間亦不確定，須視維護工作之數量而定。此外，該合約型式在決算時，須按照實際驗收數量計算契約金額，與傳統合約可能以總價給付之方式不同。由於國內目前尚無開口合約相關契約條文範本，故許多工程單位在無相關經驗下，將傳統工程合約範本作為開口合約之藍本，但其契約條文實無法完全符合維護工程執行時不定時、不定量之特性。 因此，本研究首先透過合約資料的蒐集，比較傳統合約與開口合約差異，以探討開口合約的特性；並經由專家訪談方式，瞭解目前實務上辦理開口合約現況以及相關問題之癥結，提出具體因應對策；最後並透過上述各項資料之彙整，制訂設施維護性工程之開口合約契約範本，以供相關人員參考。 Engineering facilities require regular maintenance to retain their designed functions. For public constructed facilities, they are usually installed in various years and each of these facilities may have different service conditions after years of installation. Thus, maintenance tasks often face problems such as complexity of components and indefinite quantities of components that need to be repaired. In addition, tendering of such maintenance tasks also needs to follow government procurement laws. These become tedious tasks for the agencies that are responsible for the maintenance work. Recently, roadway administration agencies use a certain type of contract termed “Indefinite Delivery Contract” (IDC) to simplify the tendering processes of the maintenance tasks. An IDC has characteristics of both indefinite quantity and indefinite time of delivery, i.e.; the contractor needs to fulfill an indefinite amount of quantities in a certain period of time only when the owner requests. Also, the final contract price is determined by the amount of quantities delivered by the contractor, as oppose to the lump sum price of a traditional contract. Since there is yet a standardized form of such IDC, often the maintenance agencies use modified traditional contract in stead, which creates disputes or problems in performing the maintenance contract. In this research, problems and corresponding solutions in performing contracts in IDC type are summarized by comparing the differences between traditional contracts and various versions of IDC, and also by interviewing experts in this field. Finally, a standardized form of IDC is also established that can be used for typical roadways maintenance works.