The universal method used to calculate & Need input of ...€¦ · FINISHES D B C D B C D B C D B C...
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3/11/2014 1 The universal method used to calculate & evaluate schedules in construction industry Developed in 1950s by DuPont & Remington Need input of project information to produce minimum project duration, start and finish time, plus project critical path 1 Process of beginning phases of construction before the design is complete When completion is 1 st priority before budget & quality. Examples: ◦ Adding metropolitan airport extension (requires minimal interruption to flight schedule) ◦ New EPL football stadium (must ready before next season starts) ◦ Replacing the only bridge connecting 2 countries which was damaged by earthquake 2
Transcript of The universal method used to calculate & Need input of ...€¦ · FINISHES D B C D B C D B C D B C...
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The universal method used to calculate & evaluate schedules in construction industry
Developed in 1950s by DuPont & Remington
Need input of project information to produce minimum project duration, start and finish time, plus project critical path
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Process of beginning phases of construction before the design is complete
When completion is 1st priority before budget & quality. Examples: ◦ Adding metropolitan airport extension (requires
minimal interruption to flight schedule)
◦ New EPL football stadium (must ready before next season starts)
◦ Replacing the only bridge connecting 2 countries which was damaged by earthquake
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LINEAR
ENTIRE
PROJECT DESIGN BID CONSTRUCTION
PHASED
SITEWORK
FOUNDATION
STRUCTURE
WALL
MEP
FINISHES
D B C
D B C
D B C
D B C
D B C D
D B C
EARLIER
CONSTRUCTION
TIME
SAVED
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Requires special contracting ◦ Not General contracting
◦ Not Single lump-sum contract
Because contractor will not commit to a locked-in price before design is completed
Ask for cost plus fee or time&material contract
Shift budget risk to owner
◦ Not multiple contractors for multiple phases
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Use Agency construction management
Owner award lump-sum contract to prime contractor for different phases
Coordinated by construction manager for the entire project
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People are not taught to be any type of manager. They are taught to perform little task, one at a time… which is to do and complete the task correctly. They are actually managing the task and start to become a project manager.
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INTRODUCTION TO CPM AND NETWORK SCHEDULING
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AOA (Activity-On-Arrows)
AON (Activity-On-Nodes)
PDM (Precedence Diagramming Method)
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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.
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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!
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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
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Need computer
Real-time basis
Training
Commitment
Teamwork
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1. Information: Drawing Specification BQ Knowledge & experience Constraints – date, time & resources Method of Construction & Technology Plan B?
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2. Develop the WBS 3. Estimate task duration
• By experience • Calculation : productivity rate and
resource available
IMPORTANT STEPS(cont.)
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4. Assign logic/relationships (assign predecessors/successors)
5. Log in the data using planning software (MSProject / Primavera)
6. Analyse the schedule with regard to: • Resource Constraint • Smoothing and leveling of the resource
IMPORTANT STEPS(cont.)
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CHARACTERISTICS
1. Consumes time
2. Need resources
3. Defineable start and finish
4. Assignable
5. Measurable
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ES = Early Start
EF = Early Finish = ES+Duration
LS = Late Start
LF = Late Finish = LS+Duration
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ACTIVITY DUR PRED
A 8 -
B 7 -
C 9 A
D 4 A
E 10 B
F 11 B
G 8 C
H 3 D
ACTIVITY DUR PRED
I 5 E
J 9 F
K 7 C, H
L 3 I
M 7 K, I
N 12 G
P 4 J
Q 2 L, P
SAMPLE PROJECT (Page 153)
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10
30
A 8
7 B
A 8 -
B 7 -
20
22
10
40
60
30
20 A
8
10 E
4
D
9 C
7 B
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F
C 9 A
D 4 A
E 10 B
F 11 B
70
50
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10
40
70
60
30
50 20 A
8
10 E
4
D
9 C
7 B
3
H
8
G
11
F
5
I
J
9
G 8 C
H 3 D
I 5 E
J 9 F
110
90
120
80
24
10
40
130
70
110
90
60
30 120
50 20
140
80 100
A 8
10 E
4
D
9 C
7 B
3
H
8
G
11
F
7
M 7
K
5
I
J
9
3 L
12
4
N
2 Q
P
K 7 C, H
L 3 I
M 7 K, I
N 12 G
P 4 J
Q 2 L, P
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10
40
130
70
110
90
60
30 120
50 20
140
80 100
A 8
10 E
4
D
9 C
7 B
3
H
8
G
11
F
7
M 7
K
5
I
J
9
3 L
12
4
N
2 Q
P
READY FOR CPM
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1. Project Calendar
2. Forward and Backward Pass
3. Early Start (ES) and Finish (EF)
4. Late Start (LS) and Finish (LF)
5. Total Float (TF)
6. Critical Activities
7. Highlight Critical Path
C
P
M
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Project Start Date
Global/Specific
Non-work days 1. Rest days/Weekends
2. Holidays
Repeating/Non-repeating
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FORWARD PASS
ES & EF
Total project duration
BACKWARD PASS
LS & LF
Still maintain total project duration as in forward pass
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10
40
130
70
110
90
60
30 120
50 20
140
80 100
A 8
10 E
4
D
9 C
7 B
3
H
8
G
11
F
7
M 7
K
5
I
J
9
3
L
12
4
N
2 Q
P
0
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22
27
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8
7
17
12
17
25
17 24
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FORWARD PASS OPERATION
30
10
40
130
70
110
90
60
30 120
50 20
140
80 100
A 8
10 E
4
D
9 C
7 B
3
H
8
G
11
F
7
M 7
K
5
I
J
9
3
L
12
4
N
2 Q
P
0
18
22
27 31
31
8
7
17
12
17
25
17 24
37 37
25
30 23
17
8
0
35
30
25
22
11
20
BACKWARD PASS OPERATION
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10
40
130
70
110
90
60
30 120
50 20
140
80 100
A 8
10 E
4
D
9 C
7 B
3
H
8
G
11
F
7
M 7
K
5
I
J
9
3
L
12
4
N
2 Q
P
0
18
22
27 31
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7
17
12
17
25
17 24
37 37
25
30 23
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8
0
35
30
25
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CRITICAL PATH
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100
Excavate Footing I
2 days
200
Excavate Footing II
2 days
Relationship/Logic
Activity No.
Description Duration Activity box
AON
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1
Site Work 7 d
2
Foundation 24 d
3
Wood Frame 14 d
9
Concrete Slabs 10 d
5
HVAC Rough-in 7 d
7
Plumbing Rough-in 10 d
6
Electrical Rough-in 9 d
8
Specialty Rough-in 7 d
4
Roofing 18 d
10
Exterior Finishes 16 d
11
Drywall 26 d
13
Floor Finishes 14 d
12
Paint 14 d
14
Interior Trim 9 d
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Exterior Landscaping 21 d
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Final Inspection 3 d
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Cleaning 10 d
Client Move-in
Perform Forward Pass 0 7
63 72
7 31
72 79 79 105 105 119 119 122
129
119 129 79 100
63 79 31 45
45 63 80 90
63 70 70 80 90 104
104 113
129
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1
Site Work 7 d
2
Foundation 24 d
3
Wood Frame 14 d
9
Concrete Slabs 10 d
5
HVAC Rough-in 7 d
7
Plumbing Rough-in 10 d
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Electrical Rough-in 9 d
8
Specialty Rough-in 7 d
4
Roofing 18 d
10
Exterior Finishes 16 d
11
Drywall 26 d
13
Floor Finishes 14 d
12
Paint 14 d
14
Interior Trim 9 d
15
Exterior Landscaping 21 d
16
Final Inspection 3 d
17
Cleaning 10 d
Client Move-in
Perform Backward Pass 0 7
63 72
7 31
72 79 79 105 105 119 119 122
129
119 129 79 100
63 79 31 45
45 63 80 90
63 70 70 80 90 104
104 113
129
129 129
96 110 76 86 69 76
45 63
82 98 31 45
86 96 110 119
119 129 98 119
72 79 79 105 105 119 126 129 63 72
0 7
7 31
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LS – ES or LF - EF
Shared among activities in a path
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Site Work
7 d
10
Exterior
Finishes
16 d
0 7 63 79
82 98 0 7
19 0
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A continuous chain of activities with zero TF
Longest total duration of any path
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1. Activity ID 2. Description 3. Duration 4. ES, EF, LS, LF 5. TF
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
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