2. Network Scheduling Techniques
• Increasing need of control techniques to cope
with the complexities, masses of data, and tight
deadlines.
• Project managers need better methods for
presenting technical and cost data to customers.
• Control techniques can be the basis for all
planning and predicting and help management
decide how to use its resources to achieve time
and cost goals.
3. Common network scheduling
Techniques
• Gantt or bar charts
• Networks
• Program Evaluation and Review Technique (PERT)
• Milestone charts
• Arrow Diagram Method (ADM) [Sometimes called
the Critical Path Method (CPM)]
• Precedence Diagram Method (PDM)
• Graphical Evaluation and Review Technique
(GERT)
4. Advantages of network scheduling
techniques
• They help management evaluate alternatives by answering such
questions as how time delays will influence project completion,
where slack exists between elements, and what elements are
crucial to meet the completion date.
• They provide a basis for obtaining facts for decision-making.
• They utilize a so-called time network analysis as the basic method
to determine manpower, material, and capital requirements, as well
as to provide a means for checking progress.
• They provide the basic structure for reporting information.
• They reveal interdependencies of activities.
• They facilitate “what if ” exercises.
• They identify the longest path or critical paths.
5. Program Evaluation and Review
Technique (PERT)
• PERT is basically a management planning and controlling
tool. It can be considered as a road map for a particular
program or project in which all of the major elements
(events) have been completely identified, together with
their corresponding interrelations
1. A big advantage of PERT lies in its extensive planning.
Network development and critical path analysis reveal
interdependencies and problems that are not obvious
with other planning methods.
2. The second advantage of PERT is that one can determine
the probability of meeting deadlines by development of
alternative plans.
6. Basic requirements of PERT/Time
1. All of the individual tasks to complete a program
must be clear enough to be put down in a
network, which comprises events and activities
(work breakdown structure)
2. Events and activities must be sequenced on the
network under a highly logical set of ground
rules that allow the determination of critical and
subcritical paths. Networks may have more than
one hundred events, but not fewer than ten.
7. Basic requirements of PERT/Time
3. In these networks, time estimates must be made
for each activity on a three-way basis.
Optimistic, most likely, and pessimistic elapsed-
time. Figures are estimated by the person(s)
most familiar with the activity.
4. The critical path and slack times are computed.
The critical path is that sequence of activities
and events whose accomplishment will require
the greatest time.
8. Composition of Networks in PERT
1. Event: Equivalent to a milestone indicating when an
activity starts or finishes.
2. Activity: The element of work that must be
accomplished.
3. Duration: The total time required to complete the
activity.
4. Effort: The amount of work that is actually performed
within the duration. For example, the duration of an
activity could be one month but the effort could be
just a two-week period within the duration.
5. Critical Path: This is the longest path through the
network and determines the duration of the project.
11. Conversion from bar charts to PERT chart.
PERT chart is used
to determine how
much time is
needed to
complete the
project.
12. How to construct PERT network?!!
• Two inputs are needed when constructing
PERT networks:
• First step, do events represent the start or
the completion of an activity? Event
completions are generally preferred.
• Next step is to define the sequence of events
17. How to construct PERT network?!!
• Large projects can easily be converted into
PERT networks once the following questions
are answered:
1. What job immediately precedes this job?
2. What job immediately follows this job?
3. What jobs can be run concurrently, (at the
same time)?
