Leads, Lags and... Hammocks for your PMP® Exam Preparation
The terms leads and lags are used to identify and control the timing of various activities within the project. It is important to accurately document leads and lags.
Lead Time: Let's assume a project has two pieces that need to be completed at the same time. Work package A will take 4 weeks to complete, but work package B only takes one week. B would show in the project plan as a finish to start (FS) with a one week lead. This means the B work package component should start one week before A is scheduled to be completed.
Lag Time: Lag time can best be described as a planned or forced delay. A great example of this is a construction project that involves pouring concrete. The project plan must include a lag time of 2 days for the concrete to dry before the next phase can begin.
Hammock Activity: Hammock activity is also frequently referred to as summary activity. These are activities that are roughly related and are reported as a single activity. Some times the relationship between the activities is clear, other times they may only be related because their completion leads to the same result. On a gantt chart a hammock activity is usually displayed as a thick black bar above a grouping of lower level activities.