Managing Resources Through Allocation and Leveling via Manual and Computer Applications
L. Jenkins and Daryl L. Orth
Too often, a construction schedule is generated without considering that many of the necessary resources are in limited supply. Since the duration of each work activity is dependent on the availability of resources, problems arise when work proceeds without taking into account how the limited amount of labor, equipment, and materials will impact the schedule. Therefore, allocating resources into the schedule is necessary to determine whether or not there is a sufficient supply of resources on hand to perform the work as planned. By comparing the availability of the desired resources against the quantity of labor, equipment, or material required to work the schedule, one is able to manage resource use in the schedule. Upon the completion of the allocation stage, resource leveling is then used to minimize the problems associated with insufficient quantities and/or fluctuations in resource demand. This paper will illustrate the issues and resolutions pertaining to resource allocation and leveling through the use of an example problem, and provide a comparison of two popular computer-scheduling software programs used today.
Key Words: Resource Loading, Resource Allocation, Resource Leveling, Construction Scheduling, Pre-Planning
success of a construction schedule is determined by its timely completion.
Through a carefully planned sequence, the schedule coordinates the assembly of
individual work activities by dictating start and completion dates. The total
number of days it takes to build a project is controlled by the durations of the
scheduled work activities. The duration of each work activity is equal to the
quantity of work divided by the production rate. Shortages of essential
resources can affect the performance and completion of scheduled work activities
by lowering the planned production rate and thereby extending the planned
duration of work beyond the anticipated completion date (Callahan, 1992).
Ignoring constraints placed on the schedule by the limited supply of resources
lessens the effectiveness of using the construction schedule as a management
tool (Glavinich, 1994). Therefore, the resource requirements for each activity
should be evaluated before a schedule is put into action. Resource
allocation, also known as resource loading, is the process that breaks down
work activities into the types and quantities of labor, equipment, and materials
needed to perform the work. As a result, one is able to determine the
anticipated resource needs, and plan accordingly. Resource leveling takes
the management of resources one step further by analyzing the resource needs of
the entire construction project and attempting to minimize the problems
associated with insufficient quantities and/or fluctuations in resource demand
on a day-to-day basis. While computer-based programs may be used to allocate and
level resources within the schedule, the authors feel a basic knowledge of the
allocation/leveling process is important. The applications of both resource
allocation and leveling are explained in this paper through the use of a
scheduling, example problem.
performed on construction job sites requires the utilization of labor,
equipment, and materials resources. As previously stated, shortages in the
quantity or availability of any essential resources can affect the performance
and completion of scheduled work. Therefore, the resource requirements for each
activity should be evaluated before a schedule is put into action. By allocating
the labor, equipment, and materials required to perform each individual task on
the schedule, one is able to pre-plan the anticipated resource needs for each
workday of the project before the schedule is put into action. This total
resource requirement is then compared with the quantity (supply) on-hand. If the
supply on-hand exceeds the requirement, then the schedule can be worked as
planned. If it is found that the demand exceeds supply, then steps need to be
taken to ensure that the proper amount of resource will be on hand on the date
needed. It should be noted that the Resource Allocation process only determines
whether or not there is a problem when comparing resource supply and demand. It
will not state the course of action needed to correct the problem.
example problem used to illustrate Resource Allocation is shown in Figure 1. The
logic diagram shows the sequence of construction and is reflected in the
attached bar chart. The resource to be analyzed for the example problem will be Workers.
1. Example problem.
hypothetical construction company responsible for the project illustrated in
Figure 1 employs 6 workers within the company, and wishes to use 4 of these
workers on our example project. Therefore, the normal number of Workers
will be equal to four, and the maximum number that could possibly be available
will be equal to 6 workers. Note that the number of workers required for each
workday for each individual work activity is shown in the Workers column
on the bar chart in Figure 1.
Figure 2, using the same information found in Figure 1, these workers are
allocated to the activity bars representing each activity. The total of each
day’s need for workers is shown in the row entitled “Total” in the lower
part of the bar chart.
2. Resource-Allocated schedule.
that the total number of workers required for Days 1 through 3 requires seven
workers per day. This demand exceeds the maximum number of workers available in
the company, so this schedule cannot be worked with the amount of resources
on-hand. By having taken the action of allocating the resources into the
schedule prior to start, one was able to determine that the demand would exceed
the supply on-hand. Implementing this schedule with only the six workers that
are employed will result in productivity lower than anticipated. Delays will be
experienced unless additional resources (workers) are made available through
either hiring extra workers or changing the sequence of work activities. Without
prior allocation of resources, this fact would not have been discovered until a
delay was caused by a resulting lower-than-anticipated productivity. The worker
resource requirement for the schedule shown in Figure 2 is illustrated by the
histogram in Figure 3.
3. Histogram showing number of workers required per day.
it is found in the example problem that the demand exceeds supply, one now knows
that an action must be taken to ensure that the proper amount of resource will
be on hand on the date needed. Though the resource allocation process will not
dictate the course of action that is needed to correct the problem, it is always
better to have discovered a potential problem before work is in progress.
fluctuations of resource usage of labor, equipment, or materials can be very
expensive. The expense that results from fluctuations in labor supply comes in
the form of continuous training and lay-off of new employees, or in the
mobilization and demobilization of construction equipment (Glavinich 201).
Leveling the demand for resources helps minimize the large day-to-day
fluctuations in the number of resources needed. Note in Figure 2 the fluctuation
of workers needed for Days 3 through 5 in the example schedule. Seven workers
are needed on Day 3, while only four workers are required on Day 4. Therefore,
if the current schedule is used as illustrated in Figure 2, then three workers
would either have to be used on other projects or laid-off. On Day 5, one of the
workers sent away on Day 4 would have to be sent back to the example project.
manipulate the daily resource requirements, resource leveling is now
implemented. Resource leveling
involves the delay of non-critical activities within their Total Float Limits to
manipulate the daily resource requirements. The Total Float of each activity is
the maximum amount of time (days in this case) that the activity can be delayed
without causing a delay to the project’s completion date. Critical activities
are not considered for delay due to the fact that any delay to work activities
on the critical path will delay the project completion date. The manual method
of leveling work activities in the schedule can be performed by either
formula-based or trial-and-error methods. To simplify the explanation process in
this paper, the trial-and-error method of arbitrarily delaying the start of
Activity B, a non-critical activity, by seven days, will be used. The results of
this arbitrary delay are presented in Figure 4.
4. Bar Chart schedule showing effect
of a 7-day delay in Activity B.
Activity B is delayed, its succeeding activity
(Activity E) is also affected. Also note that the Project Completion date is not
affected by the delay in Activity B. The resulting Resource Histogram showing
the results from this delay is shown in Figure 5.
5. Resource histogram after delay of Activity B.
the histogram shown in Figure 3 with the leveled histogram shown in
Figure 5. By redistributing resources (resource leveling) among the workdays of
the leveled schedule, the fluctuations in demand are lessened. Notice that the
total resource requirements for both the before and after
schedules (Figures 2 and 4) are equal to 56 units. This proves that the
resources were redistributed throughout the schedule. Therefore, no more or no
less Worker resources were spent to create this histogram. In fact, the
histogram in Figure 5 also illustrates that the hypothetical construction
company used in the example may be able to complete the work by using its
current workers in its labor force.
of Resource Management in Software Programs
Project and Primavera Project Planner are two popular scheduling software
programs used in the construction industry. Both programs allow the user to
allocate and level the type and quantity of resources required for each activity
on the schedule. The steps required to input and calculate the resource
information, however, differ slightly in each program. The same example schedule
used previously in this paper will be used to demonstrate the resource
allocation/leveling processes in both Microsoft Project and Primavera
Allocation/Leveling in Microsoft Project
allocate the resources
using Microsoft Project, the following steps are taken:
the schedule is created in Microsoft Project, use the computer mouse to select
an activity by clicking on an Activity in the Task Name field.
click on the Assign Resources icon located on the toolbar shown at the top of
the computer screen (see Figure 6).
the Units field of the Assign Resources window is filled in.
The number of workers
required for the activities is based on percentages (one worker = 100%, two
workers = 200%, etc.) Based on our example schedule, four workers are required
to perform the work for Activity A. Therefore, in Microsoft Project, 400% is
used in the Units field of the Assign Resources window.
Creating/Assigning resources in Microsoft Project.
the resource is created, the maximum quantity of the resource available is set
by clicking on the Resource Sheet icon and placing its value in the Maximum
Units column (see Figure 7 below).
Setting resource limits.
that the option to set normal limits is not available in Microsoft Project. Once
the resources have been allocated and their respective maximum values have been
input, the resource usage histogram may be viewed by clicking on the Resource
Microsoft Project resource graph (histogram).
histogram shown in Figure 8 illustrates the resource usage/requirements before
any leveling is performed. Note that the histogram shown in Figure 8 reflects
the same information found in the histogram found in Figure 3. Since the worker
resource is over-allocated during the first three days of the project, leveling
will be used to minimize the fluctuations in resource needs.
level the resources
in the Microsoft Project schedule, click on the Tools menu and select the
Resource Leveling option. The results shown in Figure 9 were obtained by
applying an Automatic Leveling of the entire project.
Resource histogram for leveled schedule.
Allocation/Leveling in Primavera Project Planner
using Primavera Project Planner, the following steps are taken:
resources can be allocated to each activity in a Primavera Project Planner
schedule, the resource(s) must be created in the Resource Dictionary. Click on
the Data menu (located at the top of the toolbar) and select the Resources
option (see Figure 10). Input a four-character abbreviation in the Resource
column and its explanation in the Description column. Input the normal and
maximum levels in the Limits section of the Resources Window. Hit the Close
button when input is complete.
Resources detail window.
are allocated to the appropriate activities by way of
the Activity Form icon (see Figure 11).
Resource icons in Primavera Project Planner.
the Resource Button (abbreviated as “Res”) in the Activity Form located on
the bottom half of the screen (see Figure 11).
Highlight an activity of the schedule and input the type of resource(s) needed
to perform the work by clicking in the Resource field. Enter the quantity of
resources needed in the Units Per Day row (see Figure 12).
Detail of Resources button window for Activity A.
allocating the resources to each activity on the schedule, the Resource Profile
(Histogram) is generated by clicking on the Resource/Cost Profile icon (see
Figure 11). Next, the Resource Profile Display Options should be set as follows:
Time Interval=Days, Histogram Option is “checked,” and the options Draw
Limits and Emphasize Overload with Color are “checked” (see Figure 13).
Resource profile display options.
histogram for the example schedule is shown in Figure 14. Note that this
histogram matches the previous resource histograms.
Resource histogram in Primavera Project Planner.
level the resources
using Primavera Project Planner, click the Level icon (see Figure 11) to level
histogram shown in Figure 15 reflects forward, time-constrained leveling. Again,
note that it agrees with the previous leveled histograms shown in this paper.
Leveled schedule in Primavera Project Planner.
Microsoft Project and Primavera Project Planner provided the same values when
the example schedule was allocated and leveled through the use of the respective
software programs. Therefore, since each program will provide information to
help with the management of resources, deciding which of these
computer-scheduling programs to use is a matter of personal preference. However,
it should be noted that algorithms used by scheduling software might not offer
the best solution to a resource-leveling problem (Glavinich, 1994). The
individual manager should analyze the solution presented by the computer to
determine if it is realistic and meets the needs of the company. If the solution
is deemed unsuitable, one only needs to reset back to the original schedule by
hitting the Schedule icon in Primavera Project Planner or by selecting
the Clear Leveling option in Microsoft Project.
success of a construction schedule is determined by its timely completion. The
impact of the limited resource supplies and the corresponding effect on the
project’s completion date should be analyzed prior to the implementation of
the schedule. This action is important due to the fact that the duration of each
work activity is dependent on the availability of resources. Allocating
resources into the schedule is necessary to determine if there is a sufficient
supply of resources on hand to perform the work as planned. In addition to the
quantity of resources available, problems may exist in the daily fluctuations of
resource demand. Therefore, resource leveling is used to minimize the day-to-day
fluctuations. While the manual method of allocating and leveling resources is
discussed in this paper, it is the opinion of the authors that resource
management of today’s fast-paced and complex schedules is only practicable
through the use of computerized scheduling programs. However, one must analyze
the practicability of the solution presented by the software before it is
implemented. The example problem shown in this paper is intended to illustrate
the importance of the resource allocation/leveling process and provide the
reader with instructions for using either Microsoft Project or Primavera Project
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