Download - MANAJEMEN PROYEK PERANGKAT LUNAK Program Pendidikan Vokasi Universitas Brawijaya Tahun 2011

MANAJEMEN PROYEKPERANGKAT LUNAK

Program Pendidikan Vokasi

Universitas Brawijaya

Tahun 2011

Pertemuan 5

Perencanaan Proyek : PDM (Presedence Diagramming Method) CPM (Critical Path Method)

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

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 reflect reality

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 both direction and time properties

Precedences consist of two parts: A relationship and a lag value or constraint Finish – to – Start FS Finish – to – Finish FF Start – to – Start SS Start – to – Finish SF

Lag = x Days ( a negative lag is

called a lead)

PDM – Precedence Diagram

PDM activities are comprised of: Activity descriptions Nodes representing the activity Arrows representing relationship /

dependency Points indicating direction of relationship /

dependency

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

Activity A Activity B


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.



PDM Time Calculations

Once the Network is constructed and duration of each activity is estimated, we can determined the following four time values: Earliest Start (ES) – The earliest possible time an

activity can begin Earliest Finish (EF) – The earliest possible time an

activity 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

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 the activity 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 the smallest 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.

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 611 2 13

ES EF

Activity

Duration

LS LF0

Lag

Forward Pass Example

6 D 94

8 E 81

4 F 107

12 G 187

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 Calculation12 + 7 – 1 = 18

Backward Pass Example

18 H 2425 7 31

18 I 2124 4 27

18 J 1834 1 34

14 K 1719 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 Calculation22 - 4 + 1 = 19

CPM Example Exercise

A6d

B11d

C20d

H20d

J20d

D13d

E9d

F20d

G6d

I13d


Forward Pass Results

A6d

B11d

C20d

H20d

J20d

D13d

E9d

F20d

G6d

I13d

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

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

34d 39d 40d 52d


Backward Pass Results

A6d

B11d

C20d

H20d

J20d

D13d

E9d

F20d

G6d

I13d

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

CPM – Float (or Slack) and Critical Path

Additional Network calculations provides other important information allowing analysis and control: Total Float (TF) – The amount of time an

activity can be delayed without delaying the overall project completion, which is equal to Late Finish minus Early Finish.

Free Float (FF) – The amount of time an activity can be delayed without delaying the start of another activity. Can be determine by subtracting the smallest Total Float going into an activity from each predecessor into that activity.

Critical Path – The path through the Network that has the longest total duration, thus it defines the shortest period of time in which the project may be completed.

Float Calculation Example


Continue with Exercise

A6d

B11d

C20d

H20d

J20d

D13d

E9d

F20d

G6d

I13d

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


Float Results

A6d

B11d

C20d

H20d

J20d

D13d

E9d

F20d

G6d

I13d

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


Critical Path Traced

A1d 6d 6d4d 3d 9d

B7d 11d 17d10d 3d 20d

C18d 20d 37d43d 25d 62d

H63d 20d 82d63d 0d 82d

J1d 20d 20d1d 0d 20d

D21d 13d 33d21d 0d 33d

E34d 9d 42d34d 0d 42d

F43d 20d 62d43d 0d 62d

G34d 6d 39d44d 10d 49d

I40d 13d 52d50d 10d 62d

SEKIAN

23

Download - MANAJEMEN PROYEK PERANGKAT LUNAK Program Pendidikan Vokasi Universitas Brawijaya Tahun 2011

Top Related