Planning and scheduling
From scope to schedule
Planning starts with scope definition, then a work breakdown structure (WBS) that decomposes deliverables into manageable work packages. From the WBS you identify activities, sequence them with dependencies, estimate durations and resources, and build a schedule. A product breakdown structure focuses on deliverables; a WBS focuses on work. Milestones mark significant points and have zero duration.
Dependencies and critical path
Dependencies are usually finish-to-start, but start-to-start and finish-to-finish also exist. Lead and lag adjust timing. The critical path is the longest path through the network and therefore determines the shortest possible project duration; activities on it have zero float. Float (slack) is the amount an activity can slip without delaying the project.
Techniques
Gantt charts display the schedule; network diagrams show logic. Crashing adds resources to shorten duration; fast tracking overlaps activities and increases risk. Rolling wave planning elaborates near-term work in detail and later work at a high level. Baselines are approved versions used to measure performance.
Traps
Common errors: calling the most important or most expensive activities 'critical'; giving milestones a duration; confusing a WBS with an organisation chart; and assuming all float is free to use, since shared float can disappear.
Worked example
Paths A-B-D = 5 + 3 + 4 = 12 weeks; A-C-D = 5 + 2 + 4 = 11 weeks. The critical path is A-B-D at 12 weeks, and C has one week of float. Rule of thumb: list every path, add the durations, and the longest total is the critical path.