Cpm & network diagrams

INTRODUCTION TO CPM
AND NETWORK SCHEDULING

PLANNING & SCHEDULING
Review

1

 AOA (Activity-On-Arrows)
 AON (Activity-On-Nodes)
 PDM (Precedence Diagramming Method)

2

New terms…?
 Critical Path Method = CPM
 The most common and easiest logic is
◦ Finish-to-Start (FS)
 CPM sets activities with Total Float(TF)=0 as
critical. These are activities that have the Early
Start(ES) and Early Finish(EF) time the same.
 Float also known as Slack.

3

 Pareto’s Law… “about 20% of activities account
for 80% of the results.”
 Identify those and manage. Many don’t have time
for these but have time for dealing with crises!

Pareto’s Law 80/20

Identify Problems
Pareto’s Way

4

 CPM helps to identify critical activities.
◦ Identify effects of changes
◦ Identify effects of change orders or delays
◦ Identify which activity gets resource first
◦ Determine when materials need to be delivered
 Easy to apply and follow visually
 Allow add-ins and analysis of “what if?”
 Useful for Court Cases
 Creates Teamwork

5

 Need computer
 Real-time basis
 Training
 Commitment
 Teamwork

6

*

* VPM Vertical Production Method

7

1. Information:
 Drawing
 Specification
 BQ
 Knowledge & experience
 Constraints – date, time & resources
 Method of Construction & Technology
 Plan B?

8

IMPORTANT STEPS(cont.)

1. Develop the WBS Break them down Open your mind

3. Estimate task duration
• By experience
• Calculation : productivity rate and
resource available

9

IMPORTANT STEPS(cont.)
1. Assign logic/relationships (assign
predecessors/successors)

3. Log in the data using planning software
(MSProject / Primavera)

5. Analyse the schedule with regard to:
• Resource Constraint
• Smoothing and leveling of the resource

10

CHARACTERISTICS
2. Consumes time
3. Need resources
4. Defineable start and finish
5. Assignable
6. Measurable

11

 ES = Early Start

 EF = Early Finish = ES+Duration

 LS = Late Start

 LF = Late Finish = LS+Duration

12

SAMPLE PROJECT (Page 153)

ACTIVITY DUR PRED ACTIVITY DUR PRED

A 8 - I 5 E

B 7 - J 9 F

C 9 A K 7 C, H

D 4 A L 3 I

E 10 B M 7 K, I

F 11 B N 12 G

G 8 C P 4 J

H 3 D Q 2 L, P

13

A 8 -
B 7 -

20
A
8

10

B 7

30

14

40
C 9

D C 9 A
20 50
A 4 D 4 A
8
E 10 B
10
60 F 11 B

B 7 E
10

F
30 70
11

15

G
40 90
8
C 9

D H
20 50 80
A 4 3
8

10 I
60 110
5

B 7 E G 8 C
10
H 3 D
F J I 5 E
30 70 120
11 9 J 9 F
16

K 7 C, H
L 3 I
G
M 7 K, I
40 90
N 12 G 8
C 9
P 4 J
N
Q 2 L, P 12
D H K
20 50 80 100
3 7 M
A 4
8 7

10 I 140
60 110
5
L
B 7 E 3 Q
10 2

P 130
F J
30 70 120 4
11 9

17

READY FOR CPM
G
40 90
8
C 9
N
12
D H K
20 50 80 100
3 7 M
A 4
8 7

10 I 140
60 110
5
L
B 7 E 3 Q
10 2

P 130
F J
30 70 120 4
11 9

18

l Project Calendar
l Forward and Backward Pass
w Early Start (ES) and Finish (EF)
C
Late Start (LS) and Finish (LF)
P
M
a Total Float (TF)
a Critical Activities
i Highlight Critical Path

19

 Project Start Date
 Global/Specific
 Non-work days
1. Rest days/Weekends
2. Holidays
 Repeating/Non-repeating

20

FORWARD PASS BACKWARD PASS
 ES & EF  LS & LF
 Total project duration  Still maintain total

project duration as in
forward pass

21

FORWARD PASS OPERATION
25
17 G
40 90
8
C 9
N
8 12 17 24 12
D H K
20 50 80 100
3 7 M
A 4
8 7 37
0
17
10 I 140
60 110
5
22 L
B 7 E 3 Q
10 2

18 27 P 130
F J
30 70 120 4 31
11 9
7
22

BACKWARD PASS OPERATION
25 25
17 17 G
40 90
8
C 9
N
8 8 12 20 17 23 24 30 12
D H K
20 50 80 100
3 7 M
A 4
8 7 37 37
0 0
17 25
10 I 140
60 110
5
22 30 L
B 7 E 3 Q
10 2

18 22 27 31 P 130
F J
30 70 120 4 31 35
11 9
7 11
23

CRITICAL PATH
25 25
17 17 G
40 90
8
C 9
N
8 8 12 20 17 23 24 30 12
D H K
20 50 80 100
3 7 M
A 4
8 7 37 37
0 0
17 25
10 I 140
60 110
5
22 30 L
B 7 E 3 Q
10 2

18 22 27 31 P 130
F J
30 70 120 4 31 35
11 9
7 11
24

AON
Relationship/Logic
Activity No.

100 200
Excavate Footing I Excavate Footing II
2 days 2 days

Description Duration
Activity box

25

Perform Forward Pass
0 7
1 63
72 72 79 79 105 105 119 119 122
Site Work 6 8 11 12 16
7d
Electrical Rough-in Specialty Rough-in Drywall Paint Final Inspection
9d 7d 26 d 14 d 3d
7 31
2
129 129
Foundation Client Move-in
24 d

31 45 63 79
79 100
3 10 119 129
15
17

Wood Frame Exterior Finishes
Exterior Landscaping
14 d 16 d Cleaning
21 d
10 d

45 63 80 90 104 113
4 9 14

Roofing Concrete Slabs Interior Trim
18 d 10 d 9d
90 104
63 70 70 80 13
5 7
Floor Finishes
HVAC Rough-in Plumbing Rough-in 14 d
7d 10 d

26


63 72
6

Electrical
Rough-in
9d

63 79
45 63 10
4
Exterior
Roofing Finishes
18 d 16 d
63 70
5

HVAC
Rough-in
7d
27


105 119 119 122
12 16

Paint Final
14 d Inspection
3d

79 100
15

Exterior
104 113
Landscaping
14
21 d

Interior
Trim
9d

28

Perform Backward Pass
0 7
1 63
72 72 79 79 105 105 119 119 122
Site Work 6 8 11 12 16
7d
0 7 Electrical Rough-in Specialty Rough-in Drywall Paint Final Inspection
9d 7d 26 d 14 d 3d
7 31 63 72 72 79 79 105 105 119 126 129
2
129 129
24 d
7 31 129 129

31 45 63 79
79 100
3 10 119 129
15
17

Wood Frame Exterior Finishes
Exterior Landscaping
14 d 16 d Cleaning
21 d
31 45 82 98 10 d
98 119 119 129
45 63 80 90 104 113
4 9 14

18 d 10 d 9d
45 63 86 96 110 119
90 104
63 70 70 80 13
5 7
Floor Finishes
7d 10 d 96 110
69 76 76 86

29

Perform Backward Pass

6

Electrical
Rough-in
9d
63 72
10
4
Exterior
Roofing Finishes
18 d 16 d
82 98
5
45 63
HVAC
Rough-in
7d
69 76 30

 LS – ES or LF - EF
 Shared among activities in a path

0 7 63 79

1 10

Site Work Exterior
7d 0 Finishes 19
16 d

0 7 82 98

31

Calculate Total Float
0 7
1

0 63 72 72 79 79 105 105 119 119 122
Site Work 6 8 11 12 16

0
0
0
0 7
7d
9d 7d 26 d 14 d 3d
7 31 63 72 72 79 79 105 105 119 126 129
2

0 129 129
24 d
7 31 129 129

31 45 63 79
79 100
3 10 119 129
0 19 15
19 17

0
Wood Frame Exterior Finishes Exterior Landscaping
14 d 16 d Cleaning
21 d
31 45 82 98 10 d
98 119 119 129
45 63 80 90 104 113
4 9 14

0
6 6
18 d 10 d 9d
45 63 86 96 110 119
90 104
63 70 70 80 13
5 7
6

6
6 Floor Finishes
7d 10 d 96 110
69 76 76 86

32

 A continuous chain of activities with zero TF

 Longest total duration of any path

33

Identify & Highlight The Critical Path
0 7
1

0 63 72 72 79 79 105 105 119 119 122
Site Work 6 8 11 0 12 0 16
0 0 7
7d
3d
9d 7d 26 d 14 d
7 31 63 72 72 79 79 105 105 119 126 129
2 0
129 129
24 d 129 129
7 31
31 45 63 79
79 100
3 10 119 129
0 19 15
19 17
0
Wood Frame Exterior Finishes Exterior Landscaping
16 d Cleaning
14 d 21 d
31 45 82 98 98 119 10 d
119 129
45 63 80 90 104 113
4 0 9 14

6 6

10 d 9d
18 d 86 96 110 119
45 63 90 104
63 70 70 80 13
5 7
6

6
6 Floor Finishes
7d 10 d 96 110
69 76 76 86

34

1. Activity ID
2. Description
3. Duration
4. ES, EF, LS, LF
5. TF

35

EXERCISE:
•CONVERT THE AOA
DIAGRAM PAGE 153 INTO
AON (5 min)
•Find critical path (5 min)

36

E F E F E F
C=9 G=8 N = 12
L F L F L F

E F
A=8
L F E F E F E F E F
D=4 H=3 K=7 M=7
L F L F L F L F

E F
E F
E F E F E F Q=2
B=7
E = 10 I=5 L=3 L F
L F
L F L F L F

E F E F E F
F = 11 J=9 P=4
L F L F L F
37

8 17 17 25 25 37
E F E F E F 37 37
C=9 G=8 N = 12
L F L F L F
0 8
E F
A=8 8 12 12 15 17 24 24 31
L F E F E F E F E F
D=4 H=3 K=7 M=7
L F L F L F L F
31 33
0 7
7 17 17 22 22 25 E F
E F
E F E F E F Q=2
B=7
E = 10 I=5 L=3 L F
L F
L F L F L F

7 18 18 27 27 31
E F E F E F
F = 11 J=9 P=4
L F L F L F
38

8 0 17 17 0 25 25 0 37
37 37
E F E F E F
C=9 G=8 N = 12
L F L F L F 37 37
0 0 8
E F 8 17 17 25 25 37
A=8 8 8 12 12 8 15 17 6 24 24 6 31
L F E F E F E F E F
0 8 D=4 H=3 K=7 M=7
L F L F L F L F
16 20 20 23 23 30 30 37
0 0 7
E F
7 8 17 17 8 22 22 10 25 31 4 33
B=7 E F E F E F E F
L F E = 10 I=5 L=3 Q=2
L F L F L F L F
4 11
15 25 25 30 32 35 35 37

7 4 18 18 4 27 27 4 31
E F E F E F
F = 11 J=9 P=4
L F L F L F
11 22 22 31 31 35 39

8 0 17 17 0 25 25 0 37
37 37
E F E F E F
C=9 G=8 N = 12
L F L F L F 37 37
0 0 8
E F 8 17 17 25 25 37
A=8 8 8 12 12 8 15 17 6 24 24 6 31
L F E F E F E F E F
0 8 D=4 H=3 K=7 M=7
L F L F L F L F
16 20 20 23 23 30 30 37
0 0 7
E F
7 8 17 17 8 22 22 10 25 31 4 33
B=7 E F E F E F E F
L F E = 10 I=5 L=3 Q=2
L F L F L F L F
4 11
15 25 25 30 32 35 35 37

7 4 18 18 4 27 27 4 31
E F E F E F
F = 11 J=9 P=4
L F L F L F
11 22 22 31 31 35 40

8 0 17 17 0 25 25 0 37
37 37
E F E F E F
C=9 G=8 N = 12
L F L F L F 37 37
0 0 8
E F 8 17 17 25 25 37
A=8 8 8 12 12 8 15 17 6 24 24 6 31
L F E F E F E F E F
0 8 D=4 H=3 K=7 M=7
L F L F L F L F
16 20 20 23 23 30 30 37
0 0 7
E F
7 8 17 17 8 22 22 10 25 33 2 35
B=7 E F E F E F E F
L F E = 10 I=5 L=3 Q=2
L F L F L F L F
4 11
15 25 25 30 32 35 35 37

Delay +2 9 2 20 20 2 29 29 2 33
E F E F E F
F = 11 J=9 P=4
L F L F L F
11 22 22 31 31 35 41

8 0 17 17 0 25 25 0 37
43 43
E F E F E F
C=9 G=8 N = 12
L F L F L F 37 37
0 0 8
E F 8 17 17 25 25 37
A=8 8 8 12 12 8 15 17 6 30 30 6 43
L F E F E F E F E F
0 8 D=4 H=3 K=7 M=7
L F L F L F L F
16 20 20 23 23 30 30 37
0 0 7
E F
7 8 17 17 8 22 22 10 25 33 2 35
B=7 E F E F E F E F
L F E = 10 I=5 L=3 Q=2
L F L F L F L F
4 11
15 25 25 30 32 35 35 37

9 2 20 20 2 29 29 2 33
E F E F E F
F = 11 J=9 P=4
L F L F L F
11 22 22 31 31 35 42

 If bar charts are plotted without doing CPM
analysis, all activities must be done as shown.

 Use CPM to:
◦ Identify types of float available
◦ Develop management style in using the floats
◦ Demonstrate teamworking spirit by sharing floats

43

 CPM is just a tool in the form of knowledge

 If you want to aim high, you cannot be normal.
How come?

44

1) PROJECT FACTORY

2) SUBPROJECT ADMINISTRATION MOBILISATION PROCUREMENT CONSTRUCTION

3) EARTHWORK FOOTING SLAB MASONRY ROOF
SUBNETWORK

4) ACTIVITY
FORMWORK REBAR CONCRETING

5) SUBACTIVITY
LABOUR MATERIAL EQUIPMENT

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45

Cpm & network diagrams

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