Lead
DE: Vorlaufzeit (Lead)
The amount of time a successor can be advanced relative to its predecessor.
Detailed Explanation
A lead is the amount of time by which a successor activity can be advanced with respect to a predecessor activity. Leads allow the next activity to start before the predecessor finishes, effectively overlapping activities to compress the schedule.
Leads are expressed as negative values in the schedule (e.g., FS -3 days means the successor can start 3 days before the predecessor finishes). They represent opportunities to fast-track the schedule by running activities in parallel where safe to do so.
Using leads requires careful risk assessment. Overlapping activities means the successor starts based on incomplete predecessor output. If the predecessor's output changes significantly, rework may be needed on the successor. Leads should only be used when the risk of rework is manageable.
Key Points
- Allows successor to start before predecessor finishes
- Expressed as negative time values (e.g., FS -3d)
- Used to compress schedule by overlapping activities
- A form of fast-tracking at the activity level
- Requires risk assessment — may cause rework
- Only use when predecessor output is sufficiently stable
Practical Example
A software project: coding takes 10 days, testing takes 5 days. Normally testing starts after coding (FS). With a 3-day lead, testing can begin 3 days before coding finishes (testing early modules while later modules are still being coded). This saves 3 days but risks rework if early code changes significantly.
Tips for Learning and Applying
Use leads only when the predecessor's early output is stable enough to act on
Assess rework risk before applying leads
Document assumptions behind each lead
Prefer leads over arbitrary schedule compression
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