基於數量之時程管控新模式研究

A Quantity-Based Project Schedule Control Method (Q-Pscm)

傳統專案管理採用實獲值管理（EVM）方法來評估專案時程績效，然而EVM方法具有理論缺陷，先前學者已陸續提出實獲時程管理（ESM）及實獲工期管理（EDM）等改進方法。但不論ESM或EDM方法，皆是以「整體計劃價值」及「整體實獲價值」進行指標計算，受到高價值非要徑作業高度影響，且忽略個別要徑作業對專案工期之衝擊；另外，無論過程如何延宕，接近專案結束時時程績效皆趨近於完美。基於上述原因，傳統專案時程績效管控方法常誤導管理人員之管理決策。為解決上述問題，本研究提出一種基於數量之時程管控新模式（稱為Q-PSCM），以取代傳統基於成本價值的EVM時程管控方法。本Q-PSCM模式利用實際施工數量作為專案作業剩餘工期之估算依據，再以要徑法計算整體專案之剩餘工期，利用現況時程、專案剩餘工期及預定工期等資訊計算專案時程績效指標。經案例實證發現，本研究所提出之Q-PSCM除可改善前述傳統方法之缺點，更精確地反映要徑與非要徑作業對於實際工期之影響外，亦有助於擬定更有效之進度管理策略。因此，本研究所提出之Q-PSCM模式，可有效提升施工進度控管之成效，對於強化目前營建專案進度管理實務，具有潛在之效益。

The traditional Earned Value Management (EVM) method suffers in several theoretical drawbacks, e.g., highly influenced by costly, rather than the critical activities; and the final schedule performance indicator will approach the baseline, even though poor schedule performance has been experienced. Former researchers have proposed Earned Schedule Management (ESM) and Earned Duration Management (EDM) to improve the weaknesses of EVM. However, those two methods adopt the overall values of Planned Value (PV) and Earned Value (EV) as bases for the project performance evaluation. They overlook the impact of critical-path activities to the project completion date and usually mislead the decision-making of project managers on schedule control. To tackle the above problems for traditional methods, the current paper presents a new schedule control method, namely the Quantity-based Project Schedule Control Method (QPSCM), which is founded on the ‘activity quantities' of the critical path instead of the overall ‘activity values' in evaluating the project schedule performance. The proposed Q-PSCM calculates the estimate to completion (ETC) duration of an activity using the quantity information and updates the estimated project completion date with critical path method; finally, the overall project schedule performance is evaluated based on the information of the current schedule, project ETC duration and project planned duration. It is found from case study results that the proposed Q-PSCM improves on the drawbacks of the traditional methods, reflects the actual project schedule performance more accurately, and is also more helpful in planning the schedule improvement strategies. It is concluded that the proposed Q-PSCM has the potential to improve on the drawbacks of the traditional project schedule management methods (e.g., EVM, ESM and EDM) for schedule control of construction projects.