Project Characteristics PERT & CPM

8/8/2019 Project Characteristics PERT & CPM

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Romana Nargus MBA(B/F)2009-2011

Introduction to PERT/CPM

Introduction to Project Management:

Project: an organized undertaking

Master of Engineering Thesis Project

Finding a jobBuilding a porch

Buying a house

Design and manufacture a car (Large Program)Put a man on the moon (Huge Program)

Definition

A project is composed of jobs, tasks or functions and activities that are related to

each other. Every project has one specific purpose and required resources like men,money, materials, machinery, minutes, etc. To plan, implement, and control the

management of large, one time projects. Applicable in Construction, Shipbuilding,

Weapons Systems Development, etc.

Applies to uncertain technology projectsApplies to variable cost resource allocation

Project Characteristics

o Single unit

o Many related activities

o Difficult production planning & inventory control

o General purpose equipment

o High labor skills

Examples of Projects

o Building construction

o New product introductiono Training seminar

o Research project, etc.

Objective of a project:

o The project should complete within elapsed time

o It should use optimum resources without delay

o It should complete with a minimum of capital investment.

Project Management:

Project Management is the application of knowledge, skills, tools and techniquesto project activities in order to meet project requirements.

Project Management: - a discipline "Art and Science".

o is an art

o is a science and has a set of tools and methods

Qualities of Project Manager:

Effective Project Manager should have the following qualities:


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o Lead by example

o Visionaries

o Technically competent

o Decisive

o Good communicators

o Good motivatorso Stand up to execs when necessary

o Support team members

o Encourage new ideas

Alternate view of Effective Project Managers:

o Leaders (also managers, administrators)

o Level headed

o Communicators

o Goal oriented

o Problem solvers (prioritization)

o

Innovatorso Work well under pressure (able to laugh)

o Technically competent, respected, aware

o Know company & its business

Project Management Objective

o To achieve the project goal effectively and efficiently

o To keep customers happy

o To keep the team focus on the goal

o To make sure that team members work well

o To share workload everyone equally

Project Management involves the following three phases:

1. Project Planning

project organizing2. Scheduling

3. Controlling

1) Project Planning: - Project plan is a map and a guide and benchmark tomeasure progress.

o Establishing objectives

o Defining project

o Creating work breakdown structure (WBS)

o Determining resources

o Forming organization

Project Organization

o Often temporary structure

o Uses specialists from entire company

o Headed by project manager


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o Coordinates activities

o Monitors schedule & costs

o Permanent structure called matrix organization

2) Project Scheduling

o Sequencing activitieso Identifying precedence relationships

o Determining activity times & costs

o Estimating material & worker requirements

o Determining critical activities

3) Project Controlling

Project Goal Setting --What do we want to achieve?

|V

Performance Measure -- What is happening?|

V

Performance Test -- Why is it happening?

|V

Corrective Action -- What should be done?

Project Management Techniques:

I. Gantt chart

II. Network Techniques

Critical Path Method (CPM) Program Evaluation & Review Technique (PERT)

I) Gantt chart:

Henry Laurence Gantt

Henry Laurence Gantt (1861-1919) was a mechanical engineer and management

consultant who is most famous for developing the Gantt chart in the 1910s. These Gantt

charts were employed on major infrastructure projects including the Hoover Dam andInterstate highway system.

Henry Laurence Gantt's legacy to management is the Gantt chart. Accepted as a

commonplace project management tool today, it was an innovation of world-wideimportance in the 1920s. But the Chart was not Gantt's only legacy; he was also a

forerunner of the Human Relations School of management and an early spokesman for

the social responsibility of business.

Life and carrier

Henry L Gantt was born into a family of prosperous farmers in Maryland in 1861.

His early years, however, were marked by some deprivation as the Civil War brought


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about changes to the family fortunes. He graduated from Johns Hopkins College and was

a teacher before becoming a draughtsman in 1884 and qualifying as a mechanical

engineer. From 1887 to 1893 he worked at the Midvale Steel Company in Philadelphia,where he became Assistant to the Chief Engineer (FW Taylor) and then Superintendent

of the Casting Department. Gantt and Taylor worked well in their early years together.

Gantt chartDuring the era of scientific management, Henry L. Gantt developed a tool for

displaying the progression of a project in the form of a specialized chart. An early

application was the tracking of the progress of ship building projects. Today, Gantt'sscheduling tool takes the form of a horizontal bar graph and is known as a Gantt chart, a

basic sample of which is shown below:

Gantt chart Format

Exemplary Gantt chart for building a house:

Duration : Jan. Feb. Mar. Apr. May. Jun. Jul.

1 activity

2 activity

3 activity

The horizontal axis of the Gantt chart is a time scale, expressed either in absolute

time or in relative time referenced to the beginning of the project. The time resolution

depends on the project - the time unit typically is in weeks or months. Rows of bars in the

chart show the beginning and ending dates of the individual tasks in the project.In the above example, each task is shown to begin when the task above it

completes. However, the bars may overlap in cases where a task can begin before thecompletion of another, and there may be several tasks performed in parallel. For such

cases, the Gantt chart is quite useful for communicating the timing of the various tasks.

For larger projects, the tasks can be broken into subtasks having their own Ganttcharts to maintain readability.


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Gantt chart Enhancements

This basic version of the Gantt chart often is enhanced to communicate more information.

o A vertical marker can used to mark the present point in time.

o The progression of each activity may be shown by shading or hatched lines in the

bar as progress is made, allowing the status of each activity to be known with

just a glance.o Dependencies can be depicted using link lines or color codes.

o Resource allocation can be specified for each task.

o Milestones can be shown.

Gantt chart Role in Project Planning

For larger projects, a work breakdown structure would be developed to identifythe tasks before constructing a Gantt chart. For smaller projects, the Gantt chart itself

may used to identify the tasks.

The strength of the Gantt chart is its ability to display the status of each activity at

a glance. While often generated using project management software, it is easy to

construct using a spreadsheet, and often appears in simple ASCII formatting in e-mailsamong managers.

For sequencing and critical path analysis, network models such as CPM or PERTare more powerful for dealing with dependencies and project completion time. Even

when network models are used, the Gantt chart often is used as a reporting tool. Editorial

note: The name of this tool frequently is misspelled as "Gannt" or Gant. The correctspelling is "Gantt."

II) Network Techniques:

Network Techniques help in designing, planning, organizing, coordinating,

controlling and in decision making in order to complete the project economically in

minimum available time and limited available resources.

More popular Techniques of Network are:

CPM Critical Path Method

PERT Programme Evaluation and Review MethodLCS Least Cost Method

RAMS Resource Allocation and Multi-project Scheduling

MAP Manpower Allocation ProcedureRPSM Resource Planning and Scheduling Method

GERT Graphical Evaluation and Review Technique

Characteristics of network diagram:

Advantages of network analysis:

Limitations of network analysis:

Objectives of network analysis:


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Features of network Techniques:

o Logical base for project planning

o Simple in nature (straight forward in concept)

o Improves coordination and communication

o Highlights Trouble spots and pinpoints responsibilities of a project manager

o Wider in applicationo Anticipates unforeseen changes in futures

o Used in Construction, Shipbuilding, Weapons Systems Development, etc.

o Applies to uncertain technology projects

o Applies to variable cost resource allocation

Applications of network analysis:

Network Diagram Representation in arrow diagram and CPM / PERT:

Network representations of a project, certain basic terms and their definitions are used:

1) Activity: any individual operation, which utilizes resources and time, and has an

end and a beginning. An arrow is commonly used to represent an activity with its headindicating the direction of progress in the project. These are usually classified into

following four categories:

Predecessor activity: - activities that must be completed immediately prior to the

start of another activity.

Successor activity: - activities that cannot be started until one of more of other

activities are completed, but immediately succeed them.

Concurrent activity: - activities which can be accomplished concurrently. It

may be noted that an activity can be a predecessor or a successor to an event or itmay be concurrent with one or more of the other activities.

Dummy activity: - it is an imaginary activity which does not consume any kind

of resource but merely depicts the technological dependence. It is represented as

broken arrow. Dummy activity is inserted in the network to clarify the activitypattern in the following situations:

a) To make activities with common starting and finishing point distinguishable

b) To maintain unique number system for different activitiesc) To keep the logical sequence of activities and their inter relationship

d) To identify and maintain the proper precedence relationship between activities

Dummy activities are used in the following situations:Fig. (A) Represents: If p and q activities are concurrent and Activity r is

successor of activity q.

Fig. (B) Represents: If activities a and e are concurrent; Activity b is aftera and

e, and activityfis after activity e.

Jobs land m in a certain project must precede the job n. On the other hand, the

job o is preceded by the job m only. Fig. (C1) shows the incorrect way since, though the


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relationship between l, m and n are correct, the diagram implies that the job must be

preceded by both the jobs l and m. The correct representation using the dummy d is

shown Fig. (C2) obvious that indicated precedence relationships are justified.

2) Event: An even represents a point in time signifying the completion of some

activities and the beginning of new ones. Except starting and finishing event, remainingall events are dual role events in the network. This is usually represented by circle O or

any geometrical symbol in a network which also called node or connector. Event can be

further classified into following three categories such as

Merge event: - when more than one activity comes and joins at an event.

Burst event: - when more than one activity leaves from an event.

Merge and burst event: - an activity may be merge and burst at the same timefrom an event.

3) Sequencing: the first prerequisite in the development of a network is to maintain the

precedence relationship. In order to make a network, following points should be taken

into consideration: What job or jobs precede it?

What job or jobs follow it?

What job or jobs could run concurrently?

What controls the start and finish of a job?

It is necessary that a network be drawn with full care. There are many ways to

draw a network. It is generally agreed that dummy activities be used as liberally as

needed in the first attempt, while revising the same network, every attempt should be

made to minimize them.

Some of the activities and their relations are given from the following examples:

a) Sequential activities: - Activity B can not start before activity A is completed oractivity B follows activity A or activity A precedes activity B.

b) Diverging activities: - Activity Q and R can not start before the completion ofactivity P. Activity Q and R could be start at same time.

c) Converging activities: - Activity N can not start before completion of activity L

and M, and these are the predecessor of activity N.

d) Mixed activities: - Activity L and M must be completed before start of activity Qand R. These are the successor activities of L and M and they are concurrent could

start at the same time.

e) Parallel activities: - In this activity chains B follows A and F follows E but bothactivity chains are completely independent of each other.

Graphical Representation of Events and Activities:

o Flow Charting - Uses Nodes and Arrows based on either in the method Activity

On Node (AON) or Activity On Arrow (AOA). Most of the practitioners used

method is AOA.

o Arrows

o An arrow leads from tail to head directionally.

o Nodes


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o A node is represented by a circle.

Activity On Node

o Task is represented by Node as the Completion of an Activity.

o Arrows Represent the Sequential Linkages between Activities

o For Example, Node 1 is Begin, Node 2 is Complete Task 1, and Node 3 isComplete Task 2.

Example:

Activity On Arrow

o Task is represented by an Arrow Bounded on Either End by a Node (Event)

o Each Event is identified by a Number

o The Activity is designated by the Leading Event Number and the Following Event

Number - i.e. Activity 1 - 2

Example:

Rules for drawing network diagram are summarized as follows:1) Each activity is represented by one and only one arrow in the network.

2) No two activities can be identified by the same end event

For example activity Z and Y (Fig. A) have the same end events. The procedure is to

introduce a dummy activity either between Z and one of end events or between Y and of

the end events. Modified representations after introducing dummy d areshown Fig. B. as a result of using the dummy activity d, activities

Z and Y can now be identified by unique end events. It must benoted that a dummy activities does not consume any time or resources.

3) In order to ensure the correct precedence relationship in the arrow diagram,

following questions must be checked whenever any activity is added to thenetwork....

What activity must be completed immediately before this activity can

start? What activities must follow this activity?

What activities must occur simultaneously with this activity?Few important suggestions for drawing network:

1) Try to avoid arrows which cross each other.

2) Use straight arrows.

3) Do not attempt to represent duration of a activity by its arrow length.4) Use arrow from left to right or right to left avoid missing two direction, vertical

and standing arrows my be used if necessary.

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5) Use dummies freely in rough draft but final network should not have any

redundant dummies.

6) The net work has only one entry point or start event and one point of emergence called the end event.

Common errors in drawing network:Three types of errors commonly observed they are

1) Dangling : - to disconnect and activity before the completion of all activities in a

network diagram is known as dangling error. This is shown in the followingdiagram. Here Dangling activity is 2 5.

2) Looping or Cycling : - drawing an endless loop in a network is known as looping

error as shown in the following figure.

3) Redundancy : - unnecessarily inserting the dummy activity in network logic isknown as error of redundancy. Shown, in the diagram activity 2 4.

Labeling the events or node by Dr. Fulkersons Rules:

A standard procedure called I J rules developed by Dr. D R Fulkerson: - They areI. A start event is the one which has arrows emerging from it but none entering it.

Find the start event and number it as oneII. Delete all arrows emerging from all numbered events. This will create at least

one new start event out of preceding events.

III. Number all new start events 2, 3, 4, and so on (no definite rule is necessary,

but numbering from top to bottom may facilitate other users in readingthe network when there are more than one new start events).

IV. Go on repeating steps number 2 and 3 until the end is reached.

Now consider the following network diagram for labeling by Fulkersons rule.

To number the nodes using Fulkersons rule, numbering of nodes 1 and 2 isobvious. Apply step II. The bottom node is the only node from jobs which is emerging

out but none entering it. This is number 3. Applying step II again, node number 4 is

easily obtained and likewise 5 can also be determined.

Using step II again, there are two starting points, and either one of them could be

numbered 6. Keeping in view the case of numbers 4, 5 and 6 all in a row, the top node isnumbered 6. Rest of the numbering procedure is simple and the complete network with

numbers is shown in the following figure.

Numbering the events by DR. Fulkersons rules:

1) There is a single initial event in the net work diagram. This initial event willhave arrows coming out of it and none entering it. Number this initial event as 1.

2) Neglect all the arrows emerging out of the initial event numbered 1. Doing so, itwill apparently provide one or more new initial events.

3) Number these apparently produced new initial events as 2, 3, 4 etc.

4) Again neglect all emerging arrows from these numbered events. This will createfew more initial evens.

5) Follow rule 3.A

B

C

D

E

F

G

H

I

J K

d


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6) Continue this operation until the last event, which has no emerging arrows, is

numbered.

The importance of good numbering procedure can hardly be claimed in a simplenetwork, but the Fulkersons procedure has cetin distinct advantages when network is

large.

First, the Fulkersons producer will always detect a close loop in the network ifthere is any. In network methods, a close loop represents an impossible event.

Second, numbers are smaller toward the start side and become larger on the end.

Third advantage will become apparent when a matrix representation of the

network is brought for computerization.

Documents

Project Characteristics PERT & CPM