Resource Leveling

Resource Leveling

In project management, resource leveling is defined in A Guide to the Project Management Body of Knowledge (PMBOK Guide) as "A technique in which start and finish dates are adjusted based on resource limitation with the goal of balancing demand for resources with the available supply".

When performing project planning activities, the planner will attempt to schedule certain tasks simultaneously. When more resources such as machines or people are needed than are available, or perhaps a specific person is needed in both tasks, the tasks will have to be rescheduled concurrently or even sequentially to manage the constraint. Project planning resource leveling is the process of resolving these conflicts. It can also be used to balance the workload of primary resources over the course of the project[s], usually at the expense of one of the traditional triple constraints (time, cost, scope).

Resource leveling is also useful in the world of maintenance management. Many organizations have maintenance backlogs. These backlogs consist of work orders. In a "planned state" these work orders have estimates such as 2 electricians for 8 hours. These work orders have other attributes such as report date, priority, asset operational requirements, and safety concerns. These same organizations have a need to create weekly schedules. Resource-leveling can take the "work demand" and balance it against the resource pool availability for the given week. The goal is to create this weekly schedule in advance of performing the work. Without resource-leveling the organization (planner, scheduler, supervisor) is most likely performing subjective selection. For the most part, when it comes to maintenance scheduling, there is less, if any, task interdependence, and therefore less need to calculate critical path and total float.

Resource leveling must not be confused with resource smoothing. Although resource leveling and resource smoothing are both resource optimization techniques used in project management, they differ in their primary goals and how they impact the project schedule. Resource leveling focuses on optimizing resource availability and potentially extending the project timeline to accommodate resource constraints. Resource smoothing, on the other hand, focusses on removing/reducing fluctuating resource requirements within a resources availability.

Resource leveling may be carried out manually, however this is often quite complicated and unrealistic.

Safran has a highly comprehensive, configurable, integrated Resource Leveling tool that, in its simplest/default form, attempts to postpone/place activities within their Total Float in order to reduce resource requirements to fit the resource’s availability.

In order to carry out resource leveling there are two basic pre-requisites. You obviously need to define one or more resources and additionally specify an Availability for each resource.

The result of the resource level process, i.e. the modified start and finish dates for the activity, are stored in the fields ‘Early Start Leveled’ and ‘Early Finished Leveled’ in addition to a number of fields containing meta data from the process.

To illustrate the concept of resource levelling consider the following simple example:

The project has four activities each with a 5-day duration and a 40 ‘hour’ manpower requirement. The activities must be completed during a 5-week period in order to meet the finish milestone. The resource’s availability is 40 hours per week and is shown by the horizontal red line in the histogram. The manhour histogram illustrates that the current schedule dates would require 160 manhours in week 23 which is a major overload and not realistic/possible.

If we switch on the Resource leveler with its default configuration, you’ll notice that Safran has ‘postponed/placed’ activities 00020 – 00040 within their total float which will then result in a resource requirement of 40 manhours per week which is within the resources availability.

The resource leveling process does not have any effect on the ‘Live’ plan set (Early Start/Early Finish) as the process has its own schedule dates (Early Start Leveled/Early Finish Leveled).

If the suggested resource leveled schedule is acceptable, the Live plan might be modified by copying the Early Start Leveled dates for the leveled activities to the relevant Start No Earlier date which would align the Live plan with the Leveled schedule.

Using the Resource Leveler

In order to use the Resource Leveler there are a few pre-requisites.

To start with, you need to have one or more resources defined.

Next, you have to define the availability of the resource(s).

Finally, you need to switch the resource leveler on as this is initially switched off. It can however be switched off/on at any time and is most often switched on when doing a leveling exercise and then switched off.

When switched off the ‘leveled fields’ (ie. ES/EF/FF/TF Leveled) are frozen with their latest values.

The 'Resource Leveling' facilities are located on the PROJECT ribbon as shown below:

The resource leveler is highly configurable, however it does have a set of ‘sensible defaults’ so that it will work without the need to re-configure.

The leveling options have to do with which type of leveling to carry out, either Time or Resource limited, and which availability basis to use. The latter is only relevant when doing a leveling exercise for a project group.

A filter may be applied to limit the leveling exercise to certain/or a group of activities.

You may also specify a priority, or order, in which activities or groups of activities are leveled first, second, third etc.

The default Resource Leveling Options for a single project and project group respectively are shown below:

Note that when working with projects groups the leveling options also allows you to choose which availability to use when leveling.

Resource Availabilities

Details of the availability for all required resources are entered separately from the resource data.

To access the resource availability register press Available Resources on the Resource Leveling tab:

An availability entry consists of a resource code, a timespan, a quantity and (optionally) a calendar.

The resource code must correspond to the resources defined in the resource set for the project.

A resource availability can be entered either in terms of QTY-per-day or as manpower. You can toggle between these two modes by clicking the QTY/Manpower mode button in the dialog window.

Adding a New Resource Availability Record

Press the New button in the window to add a new resource availability. Safran Project enters a new line into the availability window.

Deleting a Resource Availability Record

Select the resource availability record to delete and press the Delete button in the window. Safran Project prompts you to confirm the deletion of the resource availability record.

You cannot delete the entire availability table in one operation, as this must be done by deleting row-by-row.

The resource availability content may be modified at any time.

Complex resource availabilities may be modeled by entering multiple resource availability records for a single resource category.

Note in the example above that an additional 8 hours of work per day has been added for week ending with 22.6.25.

Below, the red line in the histogram depicts the resulting availability. At this moment the resource leveler has been switched off to focus on the extra availability.

When the resource leveler is switched on again, Safran takes the extra availability into consideration allowing activity 00030 and 00040 to take place in parallel in the same week.

The availability line is available in all Safran histograms, both in the Barchart editor Resources (Availabilities Visible) and Histogram sub-panels (Availability), as well as in the Histogram & S-Curve report (Entries/Availability Profile On).

Note that the Barchart editor Resources subpanel will always consider all available resources/categories in the project when presenting availability.

Both the Barchart editor Histogram and the Histogram & S-Curve report have resource filter capabilities that allows you to select activities with specific resources which will in turn limit the availability presented to contain only the filtered resource(s).

Summary

The Resource Leveling Summary tool can be quite helpful when trying to understand/analyze the results of a leveling process. It helps to give insight as to which activities have been affected and how they have been treated as a result of the process.

Activities are grouped into various categories depending on how they have been affected as shown below:

By pressing the ‘List’ button for a specific category, a list of the activities is presented in a separate window/panel. If you press the 'Goto' button Safran will jump to/set focus on a selected activity.

By pressing the ‘Set Active Filter’ button for a specific category, the barchart editor will use this as a filter and limit the editor to show only the activities for the group.

By pressing the ‘Reset Filter' button, any ‘Active Filter’ is removed and the Barchart Editor reverts to its previous state.

Prioritizing resources

This is a practical tool for prioritizing activities in the order in which resource leveling should follow. To do so, drag and drop the fields you need to prioritize.

Filter

This allows you to specify which activities should be considered in resource-leveling.

Resource leveling process

Please note that only the activities that have resources that have been defined and have available units will leveled. During the resource leveling process, two main steps take place:

1. The process starts with all the activities in the project schedule. These activities will be placed in a leveling queue and sorted by sort criteria.
2. After leveling each activity, a forward pass will be run to the first successor. The results will be analyzed, sorted, and placed in a leveling queue.

Resource leveling options

By clicking the small arrow on the left corner of resource leveling in the PROJECT ribbon, you will get two options: Time Limit and Resource Limit.

Both options will help you find the location of available resources for all activities that are selected for resource-leveling. The only difference between Time and Resource limit is that Time-Limit will set the Maximum Delay to the activities' Total Float. At the same time, the Resource Limit allows manual input of Maximum delay. Maximum delay is the number of time units permitted for each activity to delay.

The ‘At Overload’ comes with two different options, ‘Place As Early As Possible’ and ‘Place with Minimum Overload,’ available for both Time and Resource Limits.

Place As Early As Possible: Moves to the earliest possible date and does not consider the overload's size.

Place with Minimum overload: Move the activity to the minimum possible overload date.

Maximum Overloaded Activities: The number of overloaded activities can be accepted before resource leveling is canceled.