Project Preparation - Week 08

7/28/2019 Project Preparation - Week 08

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Activities (1)

An activity is an element of the project that consumes time and

which may or which in some cases may not consume any

resources

Activities can be divided into tasks

Depending on the nature of the project, It is conceivable that awork package may be comprised of several activities, of a single

activity or that two or more work packages may constitute a

activity

Activities are the building blocks of the project schedule. Aprojects activity list shows all activities and provides supporting

information including resource consumption levels, expertise

required, assumptions, constraints, expected deliverables activity

manager etc.


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Activity Sequencing &

Activity Duration Estimating

Activity Sequencing involves identifying and documenting the

logical precedence relationships between project activities.

Activities must be logically sequenced with proper precedence

relationships to support the subsequent development of a realistic

and achievable schedule. This can be accomplished manually or

with the aid of appropriate software

Activity Duration Estimating involves making an assessment of the

likely number of work periods that will be required to complete a

project activity. Ideally, an activity duration estimate should

include an indication of the range of possible time that an activity

will take to complete


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How is Activity Duration Estimated? (1)

Estimating activity durations is best done by individuals who arefamiliar with the work content. The quality of duration estimates

hinges largely on the quality of the available information. There are

several methods which are used for estimating activity duration in

projects:

Expert Judgment Individuals with specialized knowledge and

experience in resource planning and duration estimating

Analogous Duration Estimating Using similar activities asindicators of duration of an activity . Good in situations where

information is lacking


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How is Activity Duration Estimated? (2)

Quantitative Assessments For example: Work x Productivity Rate

Three-Point Estimates Takes risk into consideration (most likely,

optimistic, pessimistic)

Reserve Time In the event of contingencies


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How are Activity Resource

Requirements Estimated?

Estimating the resource requirements of activities involves

determining the type of physical resources (i.e. manpower,

materials, machinery), the quantity required and the specific time

when they will be required. Various methods are used for

estimating activity resource requirements in projects, including,for example:

Expert Judgment Individuals with specialized knowledge and

experience in resource planning and duration estimating

Published Estimating Data Available data on production rates,

unit resource costs for labor, materials etc.

Bottom-Up Estimating Decomposition of complex activities and

corresponding assessment


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Project Activity Sequencing

and Scheduling

Project Activity Sequencing is the prerequisite for developing the

project schedule. The project schedule determines the planned

start and finish dates for all project activities. It requires duration

estimates for each project activity, and is most conveniently

depicted pictorially in the form of a bar chart (the Gantt Chart), orthe more informational and much more complex - form of a

Network Diagram

There are two network diagramming techniques which are used in

project management the precedence diagramming method and

the arrow-on-node method. The precedence method tends to be

preferred by project managers over the arrow-on-node method

which has some inherent structural drawbacks


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Basic Considerations in Developing

Project Network Diagrams (1)

Networks and their containing project activities flow from left to

right

Arrows on networks indicate precedence and flow and can cross

each other

Each project activity should have a unique identification number

Looping of activities is not permissible

Conditional statements (if then ) are impermissible

Each activity in a project network have at least one predecessor

and successor activity, except the first and last project activities


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Basic Considerations in Developing

Project Network Diagrams (2)

An activity can start only when all preceding connected activities

have been completed

If there are multiple start and end activities, a single node should

be used to depict a start activity of a network diagram and a

single node should be used to depict a end activity


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The Gantt Chart

Named after the American Henry Gantt, the chart pictorially

depicts project activities in the form of rectangular horizontalbars, with the length of the bar corresponding to the duration ofthe activity in question

The main advantage of the Gantt Chart lies in its visual simplicity,but at the same time, it has a number of inherent drawbacks

which are not present in network diagramming methods andwhich hence decrease its value as a project management tool:

It does not provide adequate information on activities andresource requirements

It does not provide any indication whether the resulting projectschedule represents the least attainable project completion time

It allows the project manager to arbitrarily set the projectschedule

It is unsuitable for large, more complex projects


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Example of a Gantt Chart

Activity

Identifier

Activity Description Duration

(workdays)

1.1.2DY Work Package 1

(Design and Build

Component X)

100

1.1.3BXY Work Package 2

(Design and BuildComponent Y)

50

1.1.4TXY Work Package 3

(Test Components Xand Y)

25

1.1.5IXY Work Package 4

(Integrate ComponentsX and Y)

50

P1 P2 P3 P4 P5

Project Schedule Time Frame


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The Precedence Diagramming Method

Precedence diagramming is a method of constructing project

schedule network diagrams using boxes or rectangles known as

nodes to represent individual project activities, and connects

them with arrows to depict the dependencies between the project

activities

Activity A Activity B Activity C Activity A precedes

Activity B which

precedes Activity C

Activity X

Activity Y

Activity Z

Activity X precedes

both Activities Y and Z


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The Four Basic Types of

Precedence Relationships

Activity A Activity BFS: Finish-to-Start

Activity A must finish before

Activity B can start

Activity A

Activity B

SS: Start-to-Start

Activity B may start onceActivity A has started

Activity A Activity B

SF: Start-to-Finish

Activity B may finish once

Activity A has started

Activity A

Activity B

FF: Finish-to-Finish

Activity B cannot finish until

Activity A has finished


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Dependency Constraints

In identifying and depicting dependencies between project

activities, a number of constraints must be taken intoconsideration. Basically, there are four types of dependencies that

may influence the sequencing and time schedule of project

activities:

Technical Constraints One or more project activities provide

input for one or more other project activities

Inter-Project Constraints The deliverables from one project

serve as inputs for activities in another project (subprojects,

geographical dispersion)Date Constraints Imposition of start and finish dates on

project activities (no later than / earlier than / on this date)

Management Constraints As specified by project managers or

other primary stakeholders


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ACTIVITY

DESCRIPTION

ACTIVITYIDENTIFIER

ACTIVITYDURATION

ES EF

LS LF

SLA

CK

The CRITICAL PATH of a project is the

sequence of activities that determine the project

completion date any delay in an activity or

activities comprising the critical path will delay

the project by a corresponding amount of time

Project Network Diagrams: The Node

EARLY START: When can the activitystart at the earliest?

EARLY FINISH: When can the activityfinish at the earliest?

LATE FINISH: When can the activityfinish at the latest?

LATE START: When can the activitystart at the latest?

SLACK: The time forwhich the activity canbe delayed (also called

float)


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Constructing a Project Network Diagram:(Example of Network Components and Details)

Koll Business Information Center

Activity Description Preceding Activity

Activity Duration

A Approval of Application None 5

B Construction Plans A 15

C Traffic Study A 10

D Service Availability Check A 5

E Staff Report B, C 15F Commission Approval B, C, D 10

G Wait for Construction F 170

H Occupancy E, G 35


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The Basic

Network

Structure

Merge

Activities

Burst

Activities

A

Approval of

Application

C

Traffic Study

D

Service Avail-

ability Check

E

Staff Report

F

Commission

Approval

B

Construction

Plans

H

Occupancy

G

Wait for

Construction

Constructing a Project Network Diagram:(Graphical Depiction of the Network Components)


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Constructing a Project Network Diagram:(Determining the Forward Pass)

Application

Approval

Construction

Plans

Traffic

Study

Service

Check

Commission

Approval

Staff

Report

Wait for

Construction

Occupancy

A

B

C

D

F

E

G

H

5

15

10

5

10

15

170

35

50

205

155

105

3020

3520

20030

235200

Forward PassES + Duration = EF

20

15

10

20

15

200

35

5

5

5

30


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Application

Approval

A

5

Constructing a Project Network Diagram:(Determining the Backward Pass)

Construction

Plans

B

15

Traffic

Study

C

10

Service

Check

D

5

Commission

Approval

F

10

Staff

Report

E

15

Wait for

Construction

G

170

Occupancy

H

35

50

205

155

105

3020

3520

20030

235200

Backward PassLS + Duration = LF

50 10 20

205

2015

3020

200185

20030

235200

20

20

20

200

5

10

15

30

200185

185


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Application

Approval

A

5

Constructing a Project Network Diagram:(Determining Slack and the Critical Path)

Construction

Plans

B

15

Traffic

Study

C

10

Service

Check

D

5

Commission

Approval

F

10

Staff

Report

E

15

Wait for

Construction

G

170

Occupancy

H

35

50

205

155

105

3020

3520

20030

235200

50 10 20

205

2015

3020

200185

20030

235200

Slack = LS ESSlack = LF - EF

0

0

5

10

0

165

0

0

Documents

Project Preparation - Week 08