Introduction:
The
execution of a project follows a definite path of planning, scheduling ad
controlling. The first and the foremost aspect of a project is the project
design. It is in fact the heart of the project entity. It defines the
individual activities which go into the corpus of the project and their
interrelationship with each other. Project design enables to identify the flow
of event which must take place for the successful implementation of the
project. Network techniques help the management of an organization in
performing these functions efficiently and effectively.
NETWORK:
A
network comprises a set of exponents connected with each other in a sequential
relationship with each step till the completion of a project. Network analysis
is a system which plans both large and small projects by analyzing the project
activities. Projects are broken down into simple activities, which are then
arranged in a logical sequence. It is also decided as to which task will be
performed simultaneously and which other sequentially.
Network
Techniques:
Several
techniques of project scheduling and control such as Bar charts, Programme
Evaluation and Review Techniques (PERT) and Critical path method (CPM) are
used. Of these CPM have some to be widely used in project management as they
are very useful in the basic management functions of planning, scheduling and
control. These techniques can be applied in diverse kinds of projects like
construction of a projects, scheduling ship construction and repairs, end of
the month closing of accounts, large, research projects etc.
PERT
is concerned with two concepts:
1. Events: An event is a specific
accomplishment that occurs at a recognizable point of time and does not call
for either the need of time or resources.
2. Activities: An activity is the work
required to complete a specific event.
Steps in PERT
The first step in the development of a PERT
network is the establishment of objectives.
The second step is to schedule work breakdown
in great detail.
In the third step both technical and
managerial persons should begin to work together.
The fourth step is that each person who
participants in the application of PERT to the control of the project should
have some basic familiarity with the general nature of the work and with the
ultimate objective desired.
In PERT, time is the basic measure. It is
usually expressed in calendar weeks the project should be completed within the
stipulated optimistic time.
In order to arrive at the most reliable
estimate of time, three time estimates are usually employed under this
technique as given below:
1. The optimistic time: It
is the shortest time possible if everything goes perfectly well with no
complications, the chance of this optimum actually occurring might be one in a
hundred.
2. The pessimistic time: It
is longest time conceivable, it includes time for unusual delays and thus the
chance of its happening might be only one in a hundred;
3. The most likely time: It
would be the best estimate of what normally would occur.
The difference in these three times give a
measure of the relative uncertainty involved in the activity.
ADVANTAGES OF PERT
1. This
technique gives the management the ability to plan the best possible use of
resource to achieve a given goal within the overall time and cost limitations.
2. It
helps management to handle the uncertainties involved in programmes where no
standard time data of the Taylor – Gantt variety are available.
3. Use
of this technique for active control of project requires frequent updating and
revising the PERT calculations and this proves quite a costly affair.
LIMITATIONS OF PERT
1. The
basic difficulty comes in the way of time estimates for the completion of
activities because activities are of non – repetitive type.
2. This
technique does not consider resources required at various stages of the
project.
3. Use
of this technique for active control of a project requires updating and
revising the PERT calculations and this proves quite a costly affair.
CRITICAL
PATH METHODS (CPM)
CPM was developed in 1956 at the E.I. Dupont
Nemours & Co. U.S.A in connection with the Periodic overhauling and
maintenance of a chemical plant. It resulted in reducing the shut down period
from 130 hours to 90 hours and saving hours and saving the company $ 1 million.
CPM has two time cost estimates for each
activity ( one time cost estimates for the normal situation and the other
estimate for the crash situation) but does not incorporate any statistical
analysis in determining such time estimates. CPM operates on the assumptions
that there is a precise known time that each activity in the project will take.
ADVANTAGES
OF CPM
Besides
being applicable to schedule large and small projects it has some of the
important advantages listed below:
1. It
helps in ascertaining the time schedule.
2. With
its aid, control by the management is made easy.
3. It
makes better and detailed planning possible.
4. It
proves a standard method for communicating project plans, schedules time and
cost performance.
5. It
identifies the most critical elements and thus more attention can be paid to
these activities.
LIMITATIONS
OF CPM
1. CPM
fails to incorporate statistical analysis in determining the time estimates.
2. It
operates on the assumption that there is a precise known time that each
activity in the project will take but his may not be true in actual life.
3. It
is difficult to use CPM as a controlling device for the simple reason that one
must repeat the entire evaluation of the project each time when changes are
introduced into the network. It may be remembered that CPM was initially
developed as a static planning model and not as a dynamic controlling device.
