Hammock Activity in Project Management – Definition and Meaning
A hammock activity (also called summary duration task or frame activity) is a special type of activity in project planning whose duration is not fixed but dynamically derived from the timing of other linked activities (typically a start and an end activity or milestone). It is used to summarize overarching time spans or phases and adjust their duration flexibly to detailed planning. While it provides structural clarity and flexibility in the schedule, it is generally used for overview purposes rather than direct scheduling control.
Example, best practice, and further information
In a project plan, a hammock activity could represent the entire ‘testing phase’, starting after the last development activity and ending before the rollout phase begins. The duration of the hammock activity ‘testing phase’ automatically adjusts if the dates of the linked activities change. These activities are primarily used for structuring and visualizing higher-level timeframes (see also summary tasks in the PMBOK Guide). Using hammock activities to represent float is uncommon; buffers are typically planned separately in schedule management.