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An Integrated Efficiency-Risk Approach in Sustainable Project Control

4. Integrated Efficiency–Risk Methodology with the Combination of Two EVM and CCM Techniques

The main reason for combining the CCM and EVM methods is stated as follows:

In the CCM/BM method, which is obtained from TOC, time and time risks of the project are emphasized. As indicated in TOC, the system faces a limitation when developing. Time is the most important among the three main principles of management (i.e., time, cost, and performance). When time increases naturally, the consumed budget of the project also increases. To complete the project at a certain time, we usually have to interfere with the project scope. Therefore, we only apply time buffers in the project and ignore the cost items; the time buffers are considered the greatest constraint. Another limitation of this approach is the lack of formulas to estimate the duration and cost of the project. Note that many studies have been conducted to solve the constraints discussed in the previous sections, but they could not completely overcome these problems.

In the EVM/ES method, the emphasis is on project cost; the cost, value, and time control of the project are integrated in the method. This method is limited by the correlation between time and cost parameters, the lack of confidence in the SV and SPI compared with the CV and CPI, the lack of buffer time and cost, project risks, and the disregard for the path and critical chain of the project (i.e., what delays are related to what activities is not exactly determined). In other words, EVM/ES indices are applied based on cost without considering the impact time and are not related to path risk and the critical chain. Techniques to remove the correlation between the indices and the EDM methods, such as by combining the methods, fuzzy logic, and multivariate statistical analysis, have been used to solve some of the weaknesses of this method.

In the proposed hybrid efficiency-risk approach, the following basic steps are performed:

  • Computing the cost and schedule buffers of the projects;
  • The integration of the efficiency-risk control of the projects by managing the schedule and cost buffers;
  • Estimating the cost and duration of the project completion with maximum accuracy and efficiency, including: estimating cost at completion (hybrid efficiency–risk approach); and estimating duration at completion (hybrid efficiency–risk approach).