11/02/09 Chapter 7-Project Planning 1 Elements of Project Planning Divide project into tasks, tasks...

11/02/09 Chapter 7-Project Planning

1

Elements of Project Planning

Divide project into tasks, tasks into subtasks, subtasks into ...

Estimate duration of each task, subtask, ...

Estimate resource requirements for each task, subtask, ...(budget, personnel, facilities)

Identify precedence relations among tasks


2

Benefits of Project Planning

Communications tool

Resource allocation

Benchmarking


3

Stages of Engineering Design Projects

Enthusiasm

Disillusionment

Panic

Search for the guilty

Punishment for the innocent

Praise and honors for the non-

participants


4

Project Planning Tools

Gantt Chart

Critical Path Method (CPM)

Program Evaluation and Review

Technique (PERT)

Variations and combinations of the

above

Many available software packages

contain these tools


5

Gantt Chart for Automobile Bumper Project

Fig. 7.2

4 5 6 7 8 9 10 11 12 13 14 15 16 17 18321Task Nam e 23 24 25262728293031 22212019

Prelim inary Des ign

Build P rototype

Test Prototype

Final Design

Days


6

Enhanced Gantt Chart for Automobile Bumper Project

Fig. 7.3

4 5 6 7 8 9 10 11 12 13 14 15 16 17 18321Task Name 23 24 25 26 27 28 29 30 3122212019

Prelim inary D esign

Build P rototype

Test P rototype

F inal D esign

Days

hrs

30

20

25

40


7

Keeping Track of Project Progress on a Gantt Chart

Fig. 7.4

4 5 6 7 8 9 10 11 12 13 14 15 16 17 18321Task Nam e 23 24 25 26 27 28 29 30 3122212019

Prelim inary Design

Build Prototype

Test Prototype

Final Design

Days

hrs

30

20

25

40


8

Typical Electric Substation

Fig. E7.3.1(a)


9

Tasks for Designing and Building an Electric Substation

Table E 7.3.1

Task Duration

(days)

A. Design substation 10

B. Select site 7

C. Prepare site 3

D. Order transformers and related electrical equipment 2

E. Order concrete, fencing, and related construction

supplies

2

F. Excavate for foundation 3

G. Pour and cure concrete foundation 10

H. Erect structural frames 2

I. Install electrical equipment 3

J. Erect fence 2

K. Test electric equipment 2

L. Connect to grid 2

M. Clean up site 2


10

Gantt Chart for Substation Design and Construction

Fig. E7.3.1(b)

A

B

C

D

E

F

G

H

I

J

K

L

M

M T W Th F

Week 1

Task M T W Th F

Week 2

M T W Th F

Week 3

M T W Th F

Week 4

M T W Th F

Week 5

M T W Th F

Week 6


11

Critical Path Method (CPM)

Uses a network flow diagram to depict the precedence relations among activities (tasks)

Elements of diagram are directed line segments and nodes

Facilitates identification of activities whose timely completion are “critical” to timely completion of the project


12

CPM Notation and Conventions

An activity is an ongoing effort on a project task (directed line segment).

Every activity has an initiating event and a

closing event (nodes).

Events consume no time. Their primary role in

CPM diagrams is to separate activities.

Consecutive activities must be separated by events.

Fig. 7.6

A3

(b ) E v en ts(a) A c tiv ities


13

CPM Notation and Conventions (cont.)

No pair of events can be directly connected by more than one activity with no intervening events. If an activity R must immediately precede S and T, the relationship is depicted as follows

Fig. 7.7(a)

If activities R and S must both immediately precede T, the relationship is depicted as follows

Fig. 7.7(b)

All networks must begin with a single Start event and end with a single Finish event.

S

T

R

S

R

T


14

Dummy Activities Sometimes precedence relationships require the use of a

dummy activity (depicted by a dashed line) to indicate the appropriate relationships. Dummy activities do not take up any time.

Dummy activity is needed to correctly depict that P and

Q must precede S, and P must precede R.

Dummy activity needed when several activities have same Start and End events. Activities R and S share the same Start and End events.

Fig. 7.10

Dummy activities should be be included only when needed to display the precedence relation.

S

P R

Q

S

R


15

Precedence Relations for Several Activities of Bumper Project

Table 7.2

Activity Preceded by

Design bracket

Build bracket Design bracket

Build bumper

Drill holes in bumper Build bumper, Design bracket


16

Using Dummy Activity for Bumper Project

Fig. 7.8

(a)Shows proper precedence relations for drilling the

holes but does not include building the bracket

drill holein bumper

(c)Inclusion of a dummy activity allows

proper relations to be depicted

(b)Improperly shows that building the bracket

requires the bumper to be built first

build

brac

ket

buildbumper

design

bracket

buildbumper

drill holein bumper

buildbracket

designbracket

drill holein bumper

buildbumper

design

bracket


17

Multiple Dummy Activities

A precedes D A and B precede E B and C precede F

Fig. 7.9

D

C F

A

B E


18

Project Activities and their Precedence Relations

Table 7.1

Activity Duration Preceded by

A 3

B 3 A

C 4

D 1 C

E 3 B, D

F 2 A, B, D

G 2 C, F

H 4 G

I 1 C

J 3 E, G

K 5 F, H, I


19

Constructing a Network Diagram

Fig. 7.12

Fig. 7.11

Start

A3

B3

I1

D1

C4

Start

A3

Finish

B3

E3

H 4

G2

I1

J3

K5

F2

D1

C4


20

Example of Constructing a Network Diagram

Table E7.4.1

Fig. E7.4.1

Activity Preceded by

A

B

C

D A,B

E C

F A

G D, E, F

H C

I H

J D, E

K I, J

L G

M L, K

A

F G

EC

LB D

H

J

I K M


21

Activity Duration Preceded by A 4 — B 5 — C 4 A D 5 A E 6 A F 4 D,C G 7 F,B H 4 G,E

Another Example of Constructing a Network Diagram*

Start

Finish

A

4C 4

F 4

H4

G 7

D 5

E 6

B

5


22

The Critical Path

The critical path is the path of activities from the start event to the finish event for which delay in any activity along that path will delay the project finish.

For projects with a small number of alternative paths, the critical path can be most efficiently identified by finding the longest of the alternative paths.


23

Alternative Paths and their Length

Path Length

A-B-E-J 12 A-B-F-G-dummy-J 13

A-B-F-G-H-K 19 C-D-E-J 11

C-D-F-G-dummy-J 12 C-D-F-G-H-K 18

C-I-K 10

For the project depicted in Fig. 7.12

Table 7.3

Thus, A-B-F-G-H-K is the critical path


24

Critical Path Depicted on Network Diagram

Fig. 7.13

Start

A3

Finish

B3

E3

H 4

G2

I1

J3

K5

F2

D1

C4


25

Example Problem of Finding the Critical Path*

Path Duration

A-E-H 14

A-C-F-G-H 23

A-D-dummy-F-G-H 24

B-G-H 16

Start

Finish

A

4C 4

F 4

H4

G 7

D 5

E 6

B

5


26

Alternate Method for Determining Critical Path

This approach is more efficient for larger networks

– Use forward sweep to find earliest start (ES) for each activity

– Use backward sweep to find latest start (LS) for each activity

– Calculate total float (TF) for each activity

TF = LS - ES

– Critical Path consists of Activities with TF = 0


27

Earliest Start*

Earliest Start (ES) is the earliest time an activity can start. It is found by tracing forward (from tail to head of each activity arrow) from the project Start event to the tail of the selected activity. When several paths are possible, use the longest path as determined by the sum of the activity durations on that path.

For activity F, ES = 9

Start

Finish

A

4C 4

F 4

H4

G 7

D 5

E 6

B

5


28

Project Duration* Continue until we have ES for all activities that

terminate in the project Finish event. When duration of each of those activities are added to their respective ES times, the largest of the resulting sums is defined as the Project Duration.

For activity H, ES=20

Project Duration =20+4=24

Start

Finish

A

4C 4

F 4

H4

G 7

D 5

E 6

B

5


29

Latest Start* Latest Start (LS) is the latest time an activity can start

and still have the project completed within the Project Duration time.

LS is found by tracing backwards (from head to tail of each activity) from the project Finish event to the tail of selected activity. Make sure you reach the tail of the selected activity via the head of that activity. When several paths are possible, use the longest path as determined by the sum of the activity durations on that path. The Project Duration minus the length of this longest path is the LS for the selected activity.

For activity A, LS=24-24=0

Start

Finish

A

4C 4

F 4

H4

G 7

D 5

E 6

B

5


30

Total Float Total Float for each activity is the

difference between the latest start and the earliest start.

TF = LS - ES

The activities for which TF=0 define the critical path.


31

Summary of Total Float Calculations*

Critical Path consists of A-D-F-G-H

Activity Duration ES LS TF

A 4 0 0 0

B 5 0 8 8

C 4 4 5 1

D 5 4 4 0

E 6 4 14 10

F 4 9 9 0

G 7 13 13 0

H 4 20 20 0

Project Duration 24 24


32

Total Float Calculations

Activity Duration Earliest Start Latest Start Total Float

A 3 0 0 0 B 3 3 3 0 C 4 0 1 1 D 1 4 5 1 E 3 6 13 7 F 2 6 6 0 G 2 8 8 0 H 4 10 10 0 I 1 4 13 9 J 3 10 16 6 K 5 14 14 0

Project Duration 19

Table 7.4

For project shown in Fig. 7.12


33

Example of Critical Path Determination

Fig. E7.4.2(a)

A1

B2

D 4

H5

E6

G1

L3

M4

O7

F7

J 2K 5I

10 N6

C3


34

Summary of Example Float Calculations

Table E7.4.2

Activity ES LS TF

A 0 0 0

B 1 1 0

C 1 4 3

D 3 3 0

E 7 7 0

F 7 7 0

G 13 13 0

H 3 8 5 I 3 12 9 J 14 15 1

K 16 17 1

L 14 14 0

M 17 17 0

N 21 22 1

O 21 21 0 Project

Duration 28


35

Critical Path for Example Problem

Fig. E7.4.2(b)

A1

B2

D 4

H5

E6

G1

L3

M4

O7

F7

J 2K 5I

10 N6

C3


36

Program Evaluation and Review Technique (PERT)

Based on Critical Path Method

Replaces single estimate of activity

duration by a probability distribution

Allows estimate of probability of

completing project by a specified time


37

Typical Beta Distributions for Activity Durations

to-optimistic estimate; the shortest time within which this activity can be completed assuming everything goes right. This is the left terminus of the pdf.

tm-the most likely time required to complete the activity. This is the mode of the pdf.

tp- pessimistic estimate; the longest time it will take this activity to be completed assuming everything goes wrong. This is the right terminus of the pdf.

Fig. 7.14

totm tp

(a) Skewed-left Beta distribution

to tm tp

(b) Skewed-right Beta distribution


38

Network Diagram for PERT Example Problem

Fig. 7.15

Start

A1-3

-3

Finish

B2-3-4

E2-3-6

G1-2-4

I0-1-3

J1-3-6

K3-

5-12

F1-2-7

D1-

1-5

C3-4-10

H3-4-6


39

PERT Procedure

Calculate the expected duration te (mean)

of each activity

Calculate the variance 2 of each activity

Use te to determine the expected project

duration Te and identify the critical path

6

4 pmoe

tttt

2

2

6

op tt


40

Determination of Critical Path for PERT Example Calculation

Activity Expected Time

Variance Earliest Start

Latest Start

Total Float

A 3.00 0.44 0.00 0.50 0.50 B 3.00 0.11 3.00 3.50 0.50 C 4.83 1.36 0.00 0.00 0.00 D 1.67 0.44 4.83 4.83 0.00 E 3.33 0.44 6.50 14.84 8.34 F 2.67 1.00 6.50 6.50 0.00 G 2.17 0.25 9.17 9.17 0.00 H 4.17 0.25 11.34 11.34 0.00 I 1.17 0.25 4.83 14.34 9.51 J 3.17 0.69 11.34 18.17 6.83 K 5.83 2.25 15.51 15.51 0.00

Project Duration

21.34

Table 7.5


41

PERT Critical Path

Fig. 7.16

Start

A1-3

-3

Finish

B2-3-4

E2-3-6

G1-2-4

I0-1-3

J1-3-6

K3-

5-12

F1-2-7

D1-

1-5

C3-4-10

H3-4-6


42

Probability of Completing Project by Specified time Ts

Calculate the variance of the project duration as the sum of the variances of the activities on the critical path

Use the standard normal variable z to find the probability of completing the project in a specified time Ts

For Ts=20

From Table 5.1

Pr (z < -0.57) = 0.285

T

esS

TTz

362

001250250001440361

222222

.

......

)pathcritical(

T

KHGFDCT

570362

342120.

.

.TTz

T

esS


43

Space Station PERT Problem

Fig. E7.5.1(a)

This image is not yet available


44

Activities for Space Station PERT Problem

Table E7.5.1(a)

Activity Description

A Construct shell of module

B Order life support system and scientific experimentation package from same supplier

C Order components of control and navigational system

D Wire module

E Assemble control and navigational system

F Preliminary test of life support system

G Install life support in module

H Install scientific experimentation package in module I Preliminary test of control and navigational system in

module J Install control and navigational system in module

K Final testing and debugging


45

PERT Diagram for Space Station Project

Fig. E7.5.1(b)

Start

A25

-30-

45

F1-1-1

G4-5-7

E5-7-12

C20-25-35

B10-15-20

D3-3-5

H2-2-3

J8-

10-1

4

I4-4-6

K6-8-15

Finish


46

Summary of PERT Calculations for Space Station Project

Table E7.5.1(b)

Activity te 2 ES LS TF

A 31.67 11.11 0.00 0.50 0.50

B 15.00 2.78 0.00 19.50 19.50

C 25.83 6.25 0.00 0.00 0.00

D 3.33 0.11 31.67 32.17 0.50

E 7.50 1.36 25.83 25.83 0.00

F 1.00 0.00 15.00 34.50 19.50

G 5.17 0.25 35.00 42.83 7.83

H 2.17 0.03 35.00 35.50 0.50 I 4.33 0.11 33.33 33.33 0.00

J 10.33 1.00 37.67 37.67 0.00

K 8.83 2.25 48.00 48.00 0.00

Project Duration 56.83


47

Another PERT Example Problem*

Activity te 2 ES LS TF A 4.32 1.00 0 0 0 B 5.40 1.56 0 8.64 8.64 C 4.32 1.00 4.32 5.40 1.08 D 5.40 1.56 4.32 4.32 0 E 6.48 2.25 4.32 15.12 10.80 F 4.32 1.00 9.72 9.72 0 G 7.56 3.06 14.04 14.04 0 H 4.32 1.00 21.60 21.60 0

Project Duration 25.92

Start

Finish

A

2-4-8

C2-4

-8

F2-

4-8

H2-4-8

G 3.5-7-14

D2.

5-5-

10

E 3-6-12

B

2.5-5-10


48

Probability of Completing Project by Specified time Ts*

Calculate the variance of the project duration as the sum of the variances of the activities on the critical path

Use the standard normal variable z to find the probability of completing the project in a specified time Ts

For Ts=30

From Table 5.1

Pr (z < 1.48) = 1 - Pr (z < -1.48) = 1 - 0.067 = 0.932

T

es TTz

762001063001561001

22222

......

HGFDAT

481762

922530.

.

.TTz

T

es


49

CPM Diagram with Nodes Numbered

Fig. 7.17

3

C4

2

A3

Start 1 D 1

I1

B3

4E3

5G2

8

6

J3

7

K5

9 Finish

H4

F2


50

Calendarized Version of Network Diagram

Fig. 7.18

3

C

2A

Start 1

D

I

B

4E

5G

8

6

J

7K

9 FinishHF

dummy

0 62 4 8 10 12 14 16 18 20

Start 1 3

4


51

Activity on Node Network Diagram

Fig. 7.19

C

1

A

1

Start

3

3

2B

4

E

8

F

D

5

I

7Finish

4

4

4

G H

J

9

6 7K

9

8


52

Refined Activity on Node Network Diagram

Fig. 7.20

C,4

A,3

Start

B,3

E,3

F,2

D,1

I,1

FinishG,2 H,4

J,3

K,5

11/02/09 Chapter 7-Project Planning 1 Elements of Project Planning Divide project into tasks, tasks...

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Transcript of 11/02/09 Chapter 7-Project Planning 1 Elements of Project Planning Divide project into tasks, tasks...