Critical path DRAG (Devaux’s Removed Activity Gauge) is a new scheduling metric in critical path analysis [[critical-path-method]]. It is the amount of time that an activity on the critical path [[critical-path]] (i.e., the longest path through the project) is adding to the project’s duration or, alternatively, the amount of time by which the project completion would be pulled in by reducing a critical path activity’s [[critical-activity]] duration to zero.
Activities that are not on the critical path are said to have total float [[total-float]] or slack, i.e., the amount of time they can slip without making the project longer. Conversely, only critical path activities and delays (such as lags or constraints) have DRAG.
- DRAG can be computed in the following manner:
- If an activity has nothing in parallel, its DRAG is equal to its duration.
If an activity has other paths in parallel, its DRAG is whichever is less: its duration or the total float of the parallel activity with the least total float.
There are three commercially avaliable software packages that compute DRAG:
- Spider Project.
- PlanontheNet.com
- Sumatra.com's Project Optimizer, which ias an add-on to Microsoft Project.
DRAG has a corollary cost effect called DRAG Cost [[DRAG-Cost]], which is the amount by which project profit is decreased due to an activity’s DRAG reducing the value of the deliverable and/or increasing project cost through indirect costs attached to level-of-effort activities or overhead.