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Everything You Need to Know About Resource Leveling and Resource Smoothing
What if you were hired for a job, and it turned out the workload varied wildly from week to week. One week, you might have to put in 70 hours of hard, manual labor. Then next week, you’d mostly stand around and do nothing. In the following week, you’d be back to working 70 hours again.
Most people won’t put up with a lopsided schedule like this. Before long, they quit.
Project managers get this. Nearly every resource used in a project, from labor to equipment to materials, has a capacity or limitation.
In order to work within these constraints, they scrutinize and arrange projects to ensure that resources are distributed prudently and efficiently. Two techniques used for resource allocation are known as leveling and smoothing.
Understanding how these techniques work and where to apply them is an integral step to planning a project.
If you’re curious about the difference between resource leveling and resource smoothing, then read on. In this post we’ll define each of these terms and look at where they fall into a project planning schedule.
Definitions & Examples
When you’re first assigned a big project, the key information you receive is the objective, timeline and budget. From this, it’s possible to sketch out the project in general terms, using the critical path method.
Upon closer inspection of the sequence of tasks, however, it may become apparent that the plan simply won’t work. The labor may not be evenly distributed, or maybe resources won’t be available when they need to be. This is where leveling and smoothing come in.
Before defining these two terms, it’s necessary first to clarify everything that falls under the category of resources, and to explain how resource allocation functions in a project.
A resource may be either a person or a supply. Resources fall into three distinct categories:
- Labor. This includes hourly workers, subcontractors and salaried employees within a company.
- Equipment. This includes everything that’s required to complete a project. In a construction project for example, a backhoe and a dump truck are both pieces of equipment needed to excavate the foundation.
- Materials. This includes anything that remains within a project upon its completion. In a construction project, this includes the wood used to frame a building, and the concrete used in its foundation.
Resource allocation means assigning the required resources to each activity. This goes further than simply assigning labor, materials and equipment. It also entails identifying the amount of materials needed, and how long it’s expected to take to complete.
With these clarifications, let’s now define resource leveling and smoothing.
A Definition of Resource Leveling
Here is how the Project Management Glossary defines resource leveling: “A technique that involves amending the project schedule to keep resource use below a set limit. It is used when it is important to impose limits on resource use. Resource leveling can affect a project’s critical path”
Leveling is necessary when the demand for a resource exceeds the supply. This oftentimes occurs when two activities on the network diagram are scheduled in parallel, and both require the same resource.
For example, let’s say that Activity A and Activity B are both scheduled on a Monday, and each require the same person to work eight hours. This clearly won’t work. Leveling out the schedule requires adjusting the network diagram so that activities A and B are in sequence, rather than parallel. (An alternative to this dilemma might be to hire additional labor, which is known as crashing.)
As you can see, leveling focuses on activities on the critical path, and results in extending a project’s schedule.
Resource leveling solves scarcity issues, which affect pretty much every resource used in a project. Generally speaking, the same piece of equipment cannot be used on two activities at the same time, individuals cannot work over a certain number of hours each day, and certain materials can be difficult to obtain at certain times of the year.
A Definition of Smoothing
Here is how the Project Management Glossary defines resource smoothing: “A technique that makes use of float when allocating resources so as not to affect total project duration. It is used when project time constraints are important. Resource leveling does not affect a project’s critical path.”
Float is an activity’s wiggle room, essentially. Smoothing adjusts the start and finish times of non-critical activities.
Resource smoothing does not extend a schedule, that is to say. Rather, when resources aren’t utilized proportionally, it re-distributes them to create a more even distribution throughout a project.
For example, if you hire someone for 30 hours of work, and initially it was scheduled over two days, smoothing re-distributes the work over four or five days.
Smoothing doesn’t work in every scenario, but when it does, it’s a useful way to ensure work is performed moderately and consistently.
The Process for Using Resource Leveling and Smoothing
Before applying resource leveling and smoothing, it’s necessary to first know the sequence of a project, and any hard dependencies between tasks. Additionally, resources must be allocated to each activity.
These four steps show where to use leveling and smoothing within project planning.
- Create a Critical Path: First, establish a preliminary critical path, knowing that it may be adjusted upon further scrutiny.
- Allocate Resources: Next, allocate resources to each activity. Determine the labor, equipment and materials required for each activity, as well as the time or amount for each.
- Use Resource Leveling: This is where you take a hard look at the critical path and any resource limitations, to identify areas where resources exceed capacity. Applying the leveling technique may cause the critical path to increase.
- Use Resource Smoothing: In this final stage, identify activities with float. Rearrange resources to create a more prudent distribution. The critical path isn’t affected by smoothing.
Once leveling and smoothing have been applied to a network diagram, you can be sure that all the resources are reliably distributed.
Resource Leveling vs Smoothing: Compare and Contrast
Although leveling and smoothing are both resource allocation techniques, each serves a distinct purpose and impacts a project differently.
- The impact on the schedule: Resource leveling extends a project’s deadline. Resource smoothing only adjusts activities with float, so the end date remains the same.
- The impact on the network diagram: Resource leveling impacts the critical path. Resource smoothing only adjusts non-critical activities; it redistributes resources without affecting the critical path.
- The placement in project planning: Resource leveling is a technique that’s applied after a preliminary critical path is established. It’s a step that finalizes the critical path. Resource smoothing occurs after resource leveling is complete, and when the critical path is firm.
As you can see, each technique impacts a project slightly differently. One handy visual to distinguish leveling versus smoothing is to imagine a home remodel. Leveling is like knocking out a wall to expand a room, in order to make more space. Smoothing is about rearranging the items in the newly expanded room.
Nice and Even
Sometimes when you lay everything out using the critical path method, you quickly realize that two tasks cannot occur alongside each other. Maybe the labor supply is too thin, or the materials won’t be available in time to complete both.
Resource leveling and smoothing are both helpful techniques in solving problems of resource scarcity in projects. Leveling extends a project’s schedule, while smoothing only affects non-critical activities.
Just like leveling out gravel on a new driveway, both these techniques make everything in a project nice and even.
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