W20_Hari_Technical Lessons


In the realm of Total Cost Management, there are many skills and tools which are developed to guide and assist Project Owners/Asset Managers to track and manage projects. Particularly two aspects were relevant and provide better technique to improve current practices. In this blog, brief description of these 2 methods will be shown for general reference.

  1. Early and Late Dates in S-Curve


    During scheduling, early dates and late dates are calculated to show free float for each activity and then to determine total float for entire project.


    In execution phase, S-curves are used for project tracking and controlling. S-curves are an important project management tool. They allow the progress of a project to be tracked visually over time, and form a historical record of what has happened to date. Analyses of S-curves allow project managers to quickly identify project growth, slippage, and potential problems that could adversely impact the project if no remedial action is taken.


    The current practice is using early dates only as BCWS in S-curve, which leads to many alerts and delay trigger although the actual progress is ahead of late dates. This removes the function of S-curve as accurate progress tracking tool and generates false alarms.


    By incorporating late dates into the S-curves, visibility is improved for tracking actual progress in relation to both early dates and late dates. The example below shows the application of ED (shown as PV) and LD (shown as LV) in S-curve. Future project planning and controlling should engage ED and LD in S-curve to give visual representation of project status.




  2. Earned Schedule into EVM

The EVM technique is extensively used in government and private projects internationally, and is described by numerous standards, e.g. AS 2006, ANSI 1998. By employing EVM, the project manager can get a snapshot of the project status in terms of cost and schedule; and obtain performance metrics that guide Project Managers to take corrective actions.

However EVM does have limitations. While EVM is excellent in quantitatively expressing and analyzing project cost performance, the success has not extended to schedule performance. Main reason for gap in schedule performance results in using unit of cost rather than time resulting in SV catching up to zero at the end of project, regardless of time delays. Also comparison with time based network diagram (e.g. critical path) is difficult.

The concept of Earned Schedule as extension of EVM addressed the gaps mentioned above. ES measures unit of time, thus accurately capturing the schedule index and variance through the project life cycle. The figure below shows the additional parameter, i.e. SV(t) which is schedule variance in number of week, which is different from traditional EVM SV parameter that gives variance in unit of cost. The variation of SV(t) throughout project lifecycle is shown at the bottom. While SV is back to zero (not reflecting 5 wks delay of completion), the SV(t) shows exactly the duration delay at each time interval until finish.


In addition to SV(t), there are also other parameters introduced in ES method, which compliments EVM. The list of ES parameters are shown below against corresponding parameters in EVM. The calculation methodology of status index, future work estimates and prediction are same as EVM, but done in time domain. This gives rise to new matrix of performance indicators which are helpful to Project Managers.


Work Count: 510



[1] Czarnigowska, A., Joskowski, P., Biruk, S. (2011). Project Performance Reporting And Prediction: Extension of Earned Value Management. Retrieved from:

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