05b-perencanaan proyek lanjutan-pdm, cpm

8/13/2019 05b-Perencanaan Proyek Lanjutan-pdm, Cpm

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MANAJEMEN

PROYEK

PERANGKAT LUNAK

Program Pendidikan Vokasi

Universitas BrawijayaTahun 2011


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Pertemuan 5

Perencanaan Proyek :

PDM (Presedence Diagramming Method)

CPM (Critical Path Method)


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Critical Path Method

Advantages:

Identifies activities that control the project length

Determines shortest time for completion

Identifies activities that are critical (i.e. cannot

be delayed)

Shows available float for non-critical activities

Allows evaluation of what-if scenarios

Allows monitoring & control of fast-track projects

With software can be resource loaded and

leveled


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Critical Path Method

Disadvantages

Only as good as the effort put forth to properly

model the plan

Can be difficult to properly update

Can be easily misused

May lead to a false sense of security

Actual conditions may necessitate significant

modifications to model to accurately reflectreality


5/23

Precedence Diagramming Method (PDM)

PDM network rules:

Activities are represented by boxes or nodes that are

assigned properties of the activity they represent

Precedences are shown by arrows that have bothdirection and time properties

Precedences consist of two parts: A relationship and a

lag value or constraint

Finish

to

Start FS FinishtoFinish FF

StarttoStart SS

StarttoFinish SF

Lag = x Days

( a negative lag is

called a lead)


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PDMPrecedence Diagram

PDM activities are comprised of:

Activity descriptions

Nodes representing the activity

Arrows representing relationship / dependency

Points indicating direction of relationship /

dependency


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PDM Logic Relationships

Finish to Start (FS)Activity A must Finish before Activity B may Start.

The lag is usually zero. FS is the most common type.

Start to Finish (SF)Activity A must start before Activity B may Finish. The

lag is usually greater than either activity duration. FS is the least common type.

ctivity ctivity B

ctivity ctivity B


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PDM Logic Relationships

Finish to Finish (FF)Activity A must Finish before Activity B may Finish.

The lag value is usually greater than zero. FF is a less common type.

Start to Start (SS)Activity A must Start before Activity B may Start.

The lag value is usually greater than zero. SS is a less common type.

ctivity ctivity B

ctivity ctivity B


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PDM Time Calculations

Once the Network is constructed and duration ofeach activity is estimated, we can determinedthe following four time values:

Earliest Start (ES)The earliest possible time anactivity can begin

Earliest Finish (EF)The earliest possible time anactivity can finish

Latest Start (LS)The latest possible time an activity

can start without delaying project completion Latest Finish (LF)The latest possible time an

activity can start without delaying project completion


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PDM Time Calculations

ES and EF are determined by making a Forward

Pass (left-to-right) through the Network. ES of

an activity is equal to the latest of early finish

times of its predecessors. EF is the total of theactivity ES plus its duration.

LS and LF are determined by making a

Backward Pass (right-to-left)through the

Network. LF of an activity is equal to thesmallest of the LS times of the activities exiting

from the activity in question. LS of an activity is

equal to its LF minus its duration.


11/23

PDM Activity Notation and

Assumptions

Each activity box consists of six cells

For the following example assume all activities:

Begin on the morning of the scheduled start date

End the evening of the scheduled finish date

Using a 7-day workdays per week calendar

4 E 6

11 2 13

ES EF

Activity

Duration

LS LF

0Lag


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Forward Pass Example

6 D 9

4

8 E 8

1

4 F 10

7

12 G 18

7

2

0

0

(F to G) 10 + 0 + 1 = 11

(E to G) 8 + 0 + 1 = 9

(D to G) 9 + 2 + 1 = 12

Largest ES

Early Start Calculations

Early Finish Calculation

12 + 71 = 18


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Backward Pass Example

18 H 24

25 7 31

18 I 21

24 4 27

18 J 18

34 1 34

14 K 17

19 4 22

2

0

0

(H to K) 25 - 2 - 1 = 22

(I to K) 24 - 0 - 1 = 23

(J to K) 34 - 0 - 1 = 33

Late Finish Calculations

Late Start Calculation

22 - 4 + 1 = 19


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CPM Example Exercise

A

6d

B

11d

C

20d

H

20d

J

20d

D

13d

E

9d

F

20d

G

6d

I

13d


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Forward Pass Results

A

6d

B

11d

C

20d

H

20d

J

20d

D

13d

E

9d

F

20d

G

6d

I

13d

1d 6d 7d 17d 18d 37d 63d 82d

1d 20d 21d 33d 34d 42d 43d 62d

34d 39d 40d 52d


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Backward Pass Results

A

6d

B

11d

C

20d

H

20d

J

20d

D

13d

E

9d

F

20d

G

6d

I

13d

1d 6d 7d 17d 18d 37d 63d 82d

1d 20d 21d 33d 34d 42d 43d 62d

34d 39d 40d 52d

4d 9d 10d 20d 43d 62d 63d 82d

1d 20d 21d 33d 34d 42d 43d 62d

44d 49d 50d 62d


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Backward Pass Results

A

6d

B

11d

C

20d

H

20d

J

20d

D

13d

E

9d

F

20d

G

6d

I

13d

1d 6d 7d 17d 18d 37d 63d 82d

1d 20d 21d 33d 34d 42d 43d 62d

34d 39d 40d 52d

4d 9d 10d 20d 43d 62d 63d 82d

1d 20d 21d 33d 34d 42d 43d 62d

44d 49d 50d 62d


18/23

CPMFloat (or Slack) and Critical

Path

Additional Network calculations provides otherimportant information allowing analysis andcontrol: Total Float (TF)The amount of time an activity can

be delayed without delaying the overall projectcompletion, which is equal to Late Finish minus EarlyFinish.

Free Float (FF)The amount of time an activity canbe delayed without delaying the start of another

activity. Can be determine by subtracting the smallestTotal Float going into an activity from eachpredecessor into that activity.

Critical PathThe path through the Network that hasthe longest total duration, thus it defines the shortestperiod of time in which the project may be completed.


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Float Calculation Example


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Continue with Exercise

A

6d

B

11d

C

20d

H

20d

J

20d

D

13d

E

9d

F

20d

G

6d

I

13d

1d 6d 7d 17d 18d 37d 63d 82d

1d 20d 21d 33d 34d 42d 43d 62d

34d 39d 40d 52d

4d 9d 10d 20d 43d 62d 63d 82d

1d 20d 21d 33d 34d 42d 43d 62d

44d 49d 50d 62d


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Float Results

A

6d

B

11d

C

20d

H

20d

J

20d

D

13d

E

9d

F

20d

G

6d

I

13d

1d 6d 7d 17d 18d 37d 63d 82d

1d 20d 21d 33d 34d 42d 43d 62d

34d 39d 40d 52d

4d 9d 10d 20d 43d 62d 63d 82d

1d 20d 21d 33d 34d 42d 43d 62d

44d 49d 50d 62d

3d 3d 25d 0d

0d 0d 0d 0d

10d 10d


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Critical Path Traced

A

1d 6d 6d

4d 3d 9d

B

7d 11d 17d

10d 3d 20d

C

18d 20d 37d

43d 25d 62d

H

63d 20d 82d

63d 0d 82d

J

1d 20d 20d

1d 0d 20d

D

21d 13d 33d

21d 0d 33d

E

34d 9d 42d

34d 0d 42d

F

43d 20d 62d

43d 0d 62d

G

34d 6d 39d

44d 10d 49d

I

40d 13d 52d

50d 10d 62d


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SEKIAN

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05b-perencanaan proyek lanjutan-pdm, cpm

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