Where is my Critical Path? - article

The Critical Path Method (CPM) is a beautiful technique; it highlights in red the activities that drive your schedule in MS Project. It is a great help to the project manager to know which small subset of activities is driving the schedule.
Often though, the Critical Path seems incomplete; it does not cover the enter project duration. These are the possible causes for this:

• Special Resource Availability, like only in the weekend
• Constraint Dates, like Start-No-Earlier-Than
• Elapsed Duration Tasks that continue 24 hours a day and 7 days a week
• Resource Leveling: delaying a task in order to resolve over-allocations