Page 123 - DMGT302_FUNDAMENTALS_OF_PROJECT_MANAGEMENT

Fundamentals of Project Management

Notes Extensions to PERT/CPM

There have been several extensions to both network and chart forms of project scheduling. At
times these extensions are quite sophisticated.

Example: The application of fuzzy set theory to aid in estimating activity durations in
cases where activity durations are difficult to estimate because project activities cannot be well
defined (McMahon, 1993). In this section we briefly discuss one significant extension of traditional
scheduling methods, precedence diagramming. Elihu Goldratt’s Critical Chain (1997) is also a
significant addition to traditional scheduling methods. It uses networks that combine project
scheduling with resource allocation.

We then comment on some of the managerial implications of the two fundamental approaches
to risk management taken in this unit, statistical analysis and simulation.

Precedence Diagramming

One shortcoming of the PERT/CPM network method is that it does not allow for leads and lags
between two activities without greatly increasing the number of sub-activities to account for
this. That is, our regular network methods described earlier assume that an activity can start as
soon as its predecessor activities are completed. Sometimes, however, the restrictions are more
complex—

Example: When a follow-on activity cannot begin until a certain amount of time.

Notes There have been several extensions to both network and chart forms of project
scheduling. At times these extensions are quite sophisticated; for example, the application
of fuzzy set theory to aid in estimating activity durations in cases where activity durations
are difficult to estimate because project activities cannot be well-defined.

7.4 Planning, Scheduling & Control

Planning, Scheduling (or organising) and Control are considered to be basic Managerial functions,
and CPM/PERT has been rightfully accorded due importance in the literature on Operations
Research and Quantitative Analysis. Far more than the technical benefits, it was found that
PERT/CPM provided a focus around which managers could brainstorm and put their ideas
together. It proved to be a great communication medium by which thinkers and planners at one
level could communicate their ideas, their doubts and fears to another level. Most important, it
became a useful tool for evaluating the performance of individuals and teams. There are many
variations of CPM/PERT which have been useful in planning costs, scheduling manpower and
machine time. CPM/PERT can answer the following important questions:
1. How long will the entire project take to be completed?
2. What are the risks involved?
3. Which are the critical activities or tasks in the project which could delay the entire project
if they were not completed on time?
4. Is the project on schedule, behind schedule or ahead of schedule?
5. If the project has to be finished earlier than planned, what is the best way to do this at the
least cost?

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