Hammock activity

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A hammock activity (also hammock task) is a schedule or project planning term for a grouping of tasks that "hang" between two end dates it is tied to.[1][2][3][4]

A hammock activity can group tasks that are not related in the hierarchical sense of a Work Breakdown Structure, or are not related in a logical sense of a task dependency, where one task must wait for another.[5]

Usage includes:

  • Group dissimilar activities that lead to an overall capability, such as preparations under a summary label, e.g. "vacation preparation";
  • Group unrelated items for the purpose of a summary such as a calendar-based reporting period, e.g. "First-quarter plans";
  • Group ongoing or overhead activities that run the length of an effort, e.g. "project management".

The duration of the hammock activity (the size of the hammock) may also be set by the subtasks within it, so that the abstract grouping has a start date of the earliest of any of the subtasks and the finish date is the latest of any of the contents.

A hammock activity is regarded as a form of Summary activity[6] that is similar to a Level of Effort (LOE) activity.[7][8] Use of hammock activities is also a way to simplify the difficulties of performing Work Breakdown Structure decomposition to low levels.[9] Also, hammock tasks can represent any group of tasks in the Integrated Master Schedule (IMS) regardless of their physical location or parent Work Breakdown Structure (WBS) element.[10]


  1. ^ "COST ENGINEERING TERMINOLOGY, AACE® International Recommended Practice No. 10S-90". Retrieved 10 June 2014.
  2. ^ "A Glossary of Project Management Terms".
  3. ^ "How to Build a Hammock Task".
  4. ^ "Project Management Knowledge Summary". Retrieved 10 June 2014.
  5. ^ "Project Management Questions - Hammock Activity". Retrieved 27 Apr 2016.
  6. ^ A Guide to the Project Management Body of Knowledge (PMBOK Guide) (4th ed.). Project Management Institute. 2009. p. 450. ISBN 978-1933890517.
  7. ^ ""Level of Effort" in Primavera P6". Retrieved 10 June 2014.
  8. ^ "Level of Effort Activity - Primavera P6 step by step tutorial". Retrieved 10 June 2014.
  9. ^ Kerzner, Harold (March 2009). Project Management: A Systems Approach to Planning, Scheduling, and Controlling (10th ed.). Wiley. ISBN 978-0470278703.
  10. ^ Manazanera, Ignacio (2013). "Planning & Scheduling References Book". p. 120. Retrieved 5 May 2017.

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