FEATURED PAPER
By Alex Lyaschenko, PMP, MMath
Sydney, Australia
Abstract
Activity Drag is a relatively new schedule analysis metric used to assess opportunities for schedule optimisation. The metric analyses the impact of reducing activity durations on the project completion day. Although it was introduced over two decades ago, the metric is mainly known only to users of a few project delivery systems where it was implemented. In recent years, the metric has started gaining wider recognition.
In addition to the deterministic version of this metric, there is a probabilistic extension, Probabilistic Activity Drag, which estimates the level of Activity Drag uncertainty and measures the probability of achieving target optimisation, accounting for project uncertainty and risks.
This article describes the Probabilistic Activity Drag metric and outlines its advantages, limitations, and calculation specifics.
Activity Drag Metric
Although Activity Drag (“Drag” below), also known as Critical Path Drag, was introduced more than two decades ago by Stephen A. Devaux in his book Total Project Control8, it remains familiar mainly to users of the few project delivery systems that implemented it. In recent years, however, the metric has gained broader recognition. Articles on its practical application have appeared in project management journals, and it is referenced in the 8th edition of A Guide to the Project Management Body of Knowledge, published by the Project Management Institute5.
Activity Drag is the amount of time an activity directly contributes to the overall project duration. In other words, it represents how much earlier the project could be completed if that activity’s duration is reduced to zero. Such perspective combined with shortest possible activity duration, known as crashed duration, provides practical schedule acceleration opportunity.
For example, if an activity has a drag of 5 days, the project duration can be shortened by 5 days, assuming it is technically feasible to reduce the activity by that amount.
Definition N1: Critical Path Activity Drag is the amount of time that could potentially be saved on the project by reducing the duration of the activity (or removing the activity completely).
The author’s recent paper explains the application of the metric in complex delivery modelling scenarios2.
This measure is meaningful when the schedule is calculated with all real constraints in place, including technological logic, resource availability, material supply, and financial limits.
However, projects do not operate in a deterministic environment. Uncertainty and risk continuously influence outcomes. Before making acceleration decisions (and spending acceleration costs!), it is therefore beneficial to understand how activity behaves under these uncertainties and the probability of achieving the expected acceleration.
More…
To read entire paper, click here
How to cite this paper: Lyaschenko, A. (2026). Probabilistic Activity Drag; PM World Journal, Vol. XV, Issue VII, July. Available online at https://pmworldjournal.com/wp-content/uploads/2026/07/pmwj166-Jul2026-Lyaschenko-Probabilistic-Activity-Drag.pdf
About the Author
Alex Lyaschenko
Sydney, Australia
Alex Lyaschenko is a planning and delivery consultant with over 25 years of experience in project portfolio management across different industries and countries. He holds a Master’s degree in Mathematics from Odesa Mechnikov National University and began his career in the technology sector, and was at the origins of project management in Ukraine. He worked at Ukraine’s first project management consulting firm, where he helped establish project delivery offices across different industries and trained future project consultants.
After relocating to Australia, Alex contributed to multiple portfolio and program offices, supporting organisations in defining their vision, enhancing project delivery practices, developing standards, implementing PPM tools, and upskilling teams.
Passionate about merging data with actionable strategies, Alex continues to shape the project management field by delivering insightful presentations and practical solutions that empower organisations to make data-driven decisions. As a speaker, Alex has presented at numerous project management conferences, contributed to the 8th edition of the PMBOK Guide, and had his articles featured in leading industry publications.
Alex can be contacted at alex.lyaschenko@saluteenterprises.com.au
