ADM vs PDM

ADM vs. PDM 1

Table 6.6 Differences Differen ces between ADM and PDM Method

Item

ADM

PDM ES

A

A

Activity

1

Event

Chapter 6 - Project Planning Planning and Scheduling

TF

LS

ES LS

EF

D

A 2

EF LF

LF

ES: Early Start

LS: Late Start

EF: Early Finish

LF: Late Finish

D : Duration

TF: Total Float

ES

D A

EF

LS

TF

LF

1

ES

D B

EF

LS

TF

LF

ADM vs. PDM 2

ADM

PDM

Early Start (ES) is the earliest possible time an activity can start based on the logic & durations identified on the network. Late Star Startt (LS) (LS) is the latest possible time an activity can start without extending the completing date of the project. Early Finish (EF (EF)) is the earliest possible time an activity can finish if it is start on Early Start Time (ES) and finish within the planned duration. Late Finish (LF (LF)) is the latest possible time an activity can finish without extending the completion date of the project. Total Float (TF) is the maximum amount of time that the activity can be delayed without extending the completion time of the overall project. Chapter 6 - Project Planning Planning and Scheduling

ADM vs. PDM 3

Table 6.6 Differences between ADM and PDM Method

ADM -A and B are activities. 1, 2 and 3 are events -Activity A has ID or label 1-2 ; Activity B has ID or label 2-3 - Activity A precedes activity B

A

1

B

2

3

PDM Activity Nodes

ES

D A

EF

LS

TF

LF

Predecessor Activity

Chapter 6 - Project Planning and Scheduling

1

ES

D B

EF

LS

TF

LF

Current Activity

2

ES

D B

EF

LS

TF

LF

Successor Activity

ADM vs. PDM 4

Table 6.6 Differences between ADM and PDM Method (cont.) Item

ADM

PDM

Definition

Activity which has not duration. It is only used to show any relationship between activities.

Dummy Activity

D

or

Function •

•

If there is a situation where one event is used to show relationship more than one activity. To show a complicated relationship clearly


Dummy activity is not used in Precedence Diagram Method (PDM)

ADM vs. PDM 5


ADM Activity A & B have the same ID A: 1-2 B: 1-2

ID for Activity A & B are not same. A: 1-2 B: 1-3

A

A

False

1

Dummy 1

Activity D

or

True

2

2

B

3

B If C is to follow A & B, but D is to follow only B. (not fulfill)


If C is to follow A & B, but D is to follow only B. (use dummy)

A

C

A

C

B

D

B

D

ADM vs. PDM 6

Table 6.6 Differences between ADM and PDM Method (cont.)

Item

ADM If P, Q and R follow A, and B follows P, Q and R. The following diagram is not the correct representation of the same. P

False Dummy

1

A

Q

2

Activity

3

B

4

R

Reason: Activities P, Q and R have the same ID (2-3). D

True P

or 1

A

5 Q

2 R

3

6

Activities P has the ID (2-5), Q (2-3) and R (2-6). Chapter 6 - Project Planning and Scheduling

B

4

ADM vs. PDM 7


Item

ADM 1. 2. 3.

Dummy

D is preceded by A only E is preceded by A and B F is preceded by B and C

False

True

Activity A

D

A

B

E

B

C

F

C

D

D

or

Statement 3 not fulfill where F is preceded by A, B and C.


E

F

ADM vs. PDM 8


ADM

PDM F F S S – –

F - S

Relationship

–

S F S F

Critical Path

-

: A path consist of few activities which will determine the overall project duration.

Critical path

1.

ESX = LSX, or

2.

LFX = EFX, or

3.

Total Float (TF) = 0

-

Possible to have more than one critical path

-

Activities which lay on critical path cannot suffer any delay


ADM vs. PDM 9


Item

ADM -

PDM

Total float

: The maximum amount of time that the activity can be delayed without extending the completion time of the overall project. 1. TF = LF – D – ES, or

Total float

-

2.

TF = LS – ES ,

3.

TF = LF – EF

or

FORWARD PASS

: To establish the earliest expected start and finish times for each activity in the network.

Estimating duration duration

-

BACKWARD PASS

: To establish the latest allowable start and finish times for each activity in the network.


Example 1 - Dummy

AKTIVITY


10

PREDECESSOR

A

-

B

A

C

A

D

B,C

Example 1-

Dummy

AKTIVITY

11

PREDECESSOR

A

-

B

A

C

A

D

B,C

B

1

2

A

3

D

C

FALSE: Activity B and C have the same ID


4

Example 1-Dummy AKTIVITY

12

PREDECESSOR

A

-

B

A

C

A

D

B,C

SOLUTION:

B

5 dummy

1

A

3

2

C


D

4

Example 1 - Dummy

13

SOLUTION: (Change the note numbers)

B

3 dummy

1

A

2

4

C


D

5

Example 1 - Dummy

14

*** Other solution

dummy

1

A

3 B

2

4

C


D

5

Example 1 - Dummy

15

*** Other solution

B

1

A

2

C


4

3

dummy

D

5

Example 1 - Dummy

16

*** Other solution

B

1

A

2

dummy


4

3

C

D

5

Example 2

17

AKTIVITY


PREDECESSOR

A

-

B

A

C

A

D

B

E

B,C

Example 2 AKTIVITY

18

PREDECESSOR

A

-

B

A

C

A

D

B

E

B,C

1

A

B

D

2

3

C FALSE: - Activity B and C have the same ID - Activity D and E have the same ID - D is precedes by B & C Chapter 6 - Project Planning and Scheduling

4

E

Example 2 AKTIVITY

19

PREDECESSOR

A

-

B

A

C

A

D

B

E

B,C

1

A

B

3

2

5

C

4

FALSE: - E is precedes by C only.


D

E

Example 2 AKTIVITY

20

PREDECESSOR

A

-

B

A

C

A

D

B

E

B,C

B

3

D

SOLUTION:

1

A

2

C


5

dummy

4

E

Example 3

21

AKTIVITY


PREDECESSOR

A

-

B

-

C

-

D

A,B

E

B,C

Example 3

22

AKTIVITY

PREDECESSOR

A

-

B

-

C

-

D

A,B

E

B,C

3

A

D dummy 1 1

B

2

5

dummy 2 E

C


4

ADM vs PDM

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