In the Previous Post, we discuss the advantages of volume lag.
For example, when activity A performs preparation for activity B and: 20m, 10m3, 10 items, etc.
The proposed solution was to use: Start-to-Start + Volume lag.
The ‘Volume lag’ eliminates the problem when activity B can’t commence on time due to lower than expected progress of activity A. However, there is one more challenge: activity B not only has to start when the required volume is achieved, but also this Volume must be continuously achieved ahead of activity B.
As a quick fix, both activities may have an additional Finish-To-Finish + Volume lag dependency:
It guarantees that the completion of Activity B is ahead of Activity A but doesn’t fix the problem. If the progress of Activity A may not be stable project delivery model must reflect it. The proper solution is to apply multiple Point-to-Point Dependencies to implement additional checks.
A ‘Lag’ is a shift from the Start (or Finish) date of the Predecessor activity.
Point-to-Point dependency represents shifts from a predecessor point AND a successor point simultaneously.
Each P2P dependency has two lags: Lag Out (traditional) and Lag In:
Where:
• Lag 1 – predecessor lag
• Lag 2 – successor lag
• Both lags could be Duration or Volume based
• Volume could be defined in units or as Volume %
Alex Lyaschenko
PMO | Portfolio Planning & Delivery | PMP | P3O Practitioner | AgilePM Practitioner | Six Sigma
