Resource Allocation and Resource Leveling - Construction Project Scheduling and Control - page 143

e. Only 8 laborers available at any time, but the laborer resource may drive
the durations of activities . We show two scenarios in Figures 6.11a
and 6.11b. Other scenarios may lead to the same project duration,
22 days, or more, but not less. In this case, we “played with” activity
resource allocations, allowing durations to fluctuate on the basis of
supply (available resources) and demand (total resource requirements
for activities). Even though we did not allow resource use to exceed
8 laborers per day, we were able to finish the project in 22 days (vs.
29 days in case d). If we allow activity C to start on the last day of
activity B, we can cut the project duration to 21 days, as shown in
Figure 6.12. Also, if we allow activity M to occur in parallel with activ-
ity L, we can cut another day of the duration without going over the 8
laborers per day limit. In fact, this would be the ideal case from the
point of view of resource leveling. since we will be using the same
number of resources, 8 laborers per day, throughout the entire project.
Practically speaking, however, this is unlikely.
Discussion of Example 6.3
You may notice that in some of the figures in example 6.3, we did not use notation
on the bars to indicate critical and noncritical activities. In fact, all activities may be
considered “critical” in a way but not necessarily unique. Moving an activity—even if
doing so does not violate the logic—may disturb the resource allocation and may result
in overallocation in certain periods. Therefore, logic and resource constraints must be
met at the same time. You can use different combinations of resource allocations to
maintain the following four criteria:
1. No more than eight laborers used on any day
2. A correct total labor-day (or labor-hours) allocation for each activity
3. Satisfied logic
4. The earliest possible Project Completion date
If we classify activities as critical and noncritical and then try to use the total float
of a noncritical activity, we may impair the resource leveling. The author believes that
this area needs more research and development, particularly in the software industry,
before it can reach a stage at which the user is given all options, in a user-friendly way,
to make educated decisions. The software should be able to display different scenarios
(in layman's language), such as the following:
• You can finish the project in 92 days with no resource leveling (unlimited
resources) and no activity interruption.