What is Resource Leveling?
Resource leveling adjusts the schedule to resolve overallocation — when the plan needs a person or machine in two places at once, activities shift until demand fits capacity. Crucially, leveling can extend the critical path: fixing reality often costs time.
Its gentler sibling, resource smoothing, only shifts activities within their float, so the end date is protected — but overallocations may not fully resolve. Exam key: leveling may move the finish date; smoothing never does.
Worked example
The schedule needs the only crane at the north and south towers in the same week. Leveling shifts the south-tower lift two weeks out — the project end date slips one week, but the plan is now physically possible, which the original never was.