The term resource levelling is widely used in project management to refer resource limitation. Resource levelling is considered one of the basic elements to resource management within the project. According to the PMBOK Guide, resource levelling is a technique in which start and finish dates are adjusted based on resource constraints with the goal of balancing demand for resources with the available supply. Primavera P6 resource levelling tool enables to define the resource usage limits and monitor the overloads. It is possible to perform an efficient resource management process by using the reports and histograms of this tool. This article reviews the basics of resource levelling and demonstrates how to make an effective resource levelling in Primavera P6.
Why Do We Need Resource Levelling ?
During the planning phase, activity durations are defined and initial resource quantities are assigned to the activities to complete the activities on time. However, when the resource loading histograms are analyzed, overloaded or insufficient resource quantities may be seen. For instance you can supply maximum 1000 manpower to your project but as per the resource loading histograms obtained from the workschedule, you must bring 500 manpower for the first week, 2000 manpower for the second week and 100 manpower for the third week to complete the project on time. At this stage resource loading techniques come into play to smooth the overloaded quantities.
It can be easy to delay one task considering the critical path and total float until the resources are available. However in large and complex projects with thousands of activities, it is not possible to make all the adjustments easily. For this reason, project management softwares like Primavera P6, Microsoft Project etc. can be used to balance the workload of primary resources to solve the conflicts.
Resource Levelling in Primavera P6
If the same resources are assigned more than one activity within a project or many projects, overloads will be inevitable. Primavera P6 resource levelling tool enables to reduce the overloads by using the available activity floats.
For better understanding, let’s analyze the sample Block Valve Station construction project below as shown in the Figure 1.
Before to start resource levelling, levelling priorities should be defined. This determination can be done at the activity level, project level or both. In order to define the activity levelling priority, add the column “Activity Levelling Priority” as shown in the Figure 2.
If the levelling priority of an activity is high, Primavera P6 resource levelling tool moves the activity to perform the resource levelling. If the priority is low, the tool does not move the activity.
Now, create a labor resource named “Operator” and define max units per time as 20 hours/day from the Resources window as shown in the Figure 3.
Then, assign this newly created labor resource to the Electrical Works and Mechanical Works activities as shown in the Figure 4.
In order to see the over allocated units per day, Select View | Show on Bottom | Resource Usage Profile from the main drop down menu at the top of the screen as shown in the Figure 5.
As it is seen from the above figure, red bars represent over allocated units. Max units per time was inserted 20 hours/day from the resources window so that over allocated units are 10 hours/day.
Now, Select Tools | Level Resources from the main drop down menu at the top of the screen. This will open the Level Resources window as shown in the Figure 6.
Additional levelling priorities can be defined in this window by clicking add button at the bottom. If you don’t click the “Level resources only within activity total float”, project completion date may change. Then click Level button and see the differences between the previous and the current situation as shown in the Figure 7.
If you click the schedule button, the schedule turns back to the previous situation. To prevent this, go to the Schedule Options and click the “Level Resources During Scheduling” option as shown in the Figure 8.
Resource levelling is a part of effective resource management practices. Experienced project managers and planning engineers prepare project schedules by taking into consideration of the resource availability. Understanding the impacts of effective resource levelling help the project manager and stakeholders to analyze the problems before to face with them. Resource levelling tehcniques are closely related with critical path calculations. Therefore activity sequences and logic of the network diagram effect the required resource quanities per time.
In this simple example, we demonstrate how to perform resource levelling in Primavera P6. As it is seen from the example it is not possible to remove all the overloads completely from the schedule all the time. However it is possible to remove the overloads partially. Most of the projects are resource constrained. Therefore, an efficient resource management should be made in order to complete the project on time and budget. It is not possible to achieve the projects goals without levelling and coordination of limited resources.