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The Use of a Multiple Risk Level Model to Tackle the Duration of Risk for Construction Activity
Hsien-Kuan Chang,Wen-der Yu,Shao-Tsai Cheng,Tao-Ming Cheng 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.6
The project evaluation and review technique (PERT) is the most well-known method to handle the risk due to uncertain activity durations, previous studies show that the β-distribution-based PERT estimation tends to be over-optimistic and it offers no control of the project in terms of risk duration. This study proposes a multiple risk-level (MRL) model that uses a site spatial constraint, environmental effects and the “5 Ms” of construction management to tackle the duration of risk during a construction project. A Risk-based Critical Path Scheduling Method (R-CPSM) that uses MRL is developed to calculate the duration of the project. A case study using a project selected from a previous study is used to compare the four estimation methods: two traditional PERT methods (3.2σs and 6σs), a Monte Carlo Simulation and the proposed MRL model. The results show that, compared with traditional approaches to estimate durations of uncertain activity, the proposed R-CPSM method is more systematic that can be combined with a cost estimation process and offers a rectification mechanism that dynamically monitors and adjusts the important factors that affect the risk duration. This method gives a more realistic estimate that is in agreement with the results of previous studies.
A Quantity-Based Method to Predict More Accurate Project Completion Time
Hsien-Kuan Chang,Wen-der Yu,Tao-Ming Cheng 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.10
‘Completion in time’ is a crucial element of project management. Previous studies show that earned value management (EVM), earned schedule method, or earned duration management do not give an accurate project completion time estimation (PCTE) because of theoretical weaknesses. Inaccurate PCTE may provide misleading information, so that the project manager cannot take effective schedule control actions timely, and thus it results in failure of project time management. To improve the above-mentioned problem, this research proposes a quantity-based project duration estimating method (Q-PDEM), which calculates the PCTE using the de facto work quantities and the updated productivity information of activities. The results of two case studies show that the proposed Q-PDEM gives a 7.55% better mean absolute percentage error (MAPE) than the existing methods for predicted project completion duration for Case I, and 24.54% for Case II. It is concluded that the proposed Q-PDEM gives a more accurate estimation of the time for project completion and allows more effective control of the project schedule.