Earlier, I said that CPM and PERT do not consider resource availability. Now that you have a schedule of activities and have determined the critical path, it's time to plug in resources for those activities and adjust the schedule according to any resource constraints you discover. You should use this technique with CPM-based schedules.
Resource leveling—also called the resource-based method—is used when resources are overallocated. You'll also use this technique when they are time constrained (especially those assigned to critical path activities) or when you need to meet specific schedule dates and are concerned about resource availability.
Remember that you identified resource estimates during the Estimate Activity Resources processes. Now during Develop Schedule, resources are assigned to specific activities. Usually, you'll find that your initial schedule has periods of time with more activities than you have resources to work on them. You will also find that it isn't always possible to assign 100 percent of your team members' time to tasks. Sometimes your schedule will show a team member who is overallocated, meaning they're assigned to more work than they can physically perform in the given time period. Other times, they might not be assigned enough work to keep them busy during the time period. This problem is easy to fix. You can assign under-allocated resources to multiple tasks to keep them busy.
Having overallocated resources is a little more difficult problem to resolve than having underallocated resources. Resource leveling attempts to smooth out the resource assignments to get tasks completed without overloading the individual while trying to keep the project on schedule. This typically takes the form of allocating resources to critical path tasks first.
The project manager can accomplish resource leveling in several ways. You might delay the start of a task to match the availability of a key team member. Or you might adjust the resource assignments so that more tasks are given to team members who are underallocated. You could also require the resources to work mandatory overtime—that one always goes over well! Perhaps you can split some tasks so that the team member with the pertinent knowledge or skill performs the critical part of the task and the noncritical part of the task is given to a less-skilled team member. All these methods are forms of resource leveling.
Generally speaking, resource leveling of overallocated team members extends the project end date. If you're under a date constraint, you'll have to rework the schedule after assigning resources to keep the project on track with the committed completion date. This might include moving key resources from noncritical tasks and assigning them to critical path tasks or adjusting assignments as previously mentioned. Reallocating those team members with slack time to critical path tasks to keep them on schedule is another option. Don't forget, fast tracking is an option to keep the project on schedule also.
Reverse resource allocation scheduling is a technique used when key resources—like a thermodynamic expert, for example—are required at a specific point in the project and they are the only resource, or resources, available to perform these activities. This technique requires the resources to be scheduled in reverse order (that is, from the end date of the project rather than the beginning) in order to assign this key resource at the correct time.
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What you need to know about… Project Management Made Easy! Project management consists of more than just a large building project and can encompass small projects as well. No matter what the size of your project, you need to have some sort of project management. How you manage your project has everything to do with its outcome.