This presentation provides a good description of Project Network Diagrams. It explains: Precedence Diagramming Method, Logical Relationships, Lead & Lag, Float and Critical Path Method. It will help you in preparing for PMP Exam.
2. Project Schedule Network Diagram
Designed and Developed by Praveen Malik, PMP
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Project Schedule Network Diagrams are simply called
Network Diagrams.
Network Diagrams are used to graphically represent
logical relationships between project activities (or tasks).
Network Diagrams can be drawn using Precedence
Diagramming Method (PDM).
3. Precedence Diagramming Method(PDM)
Designed and Developed by Praveen Malik, PMP
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PDM uses nodes (boxes) and arrows to represent logical
relationship between scheduled activities
Activities are represented as nodes
Milestones are represented as small circles
Dependencies are represented as Arrows
Activities/milestones are separated by Arrows
Arrow head depicts successor activity/milestone
Arrow tail depicts predecessor activity/milestone
Multiple arrows (dependencies) are possible between activities
4. PDM Example
Designed and Developed by Praveen Malik, PMP
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A B
Y
Z
X
• B is the Successor
• A is the Predecessor
• Start of B depends on Finish of A
• Z is the Successor
• X & Y are the Predecessors
• Start of Z depends on Finish of
X&Y
5. Precedence Diagramming Method(PDM)
Designed and Developed by Praveen Malik, PMP
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PDM is also called Activity on Node (AON) method as activities are
represented as nodes (boxes)
PDM includes 4 types of logical relationships
Finish to Start (FS)
Finish to Finish (FF)
Start to Start (SS)
Start to Finish (SF)
Refer to https://www.pmbypm.com/project-network-diagram/ for more details
PDM can be used to represent
Lead or acceleration of the successor activity
Lag or mandatory delay of the successor activity
Refer to https://www.pmbypm.com/project-schedule-leads-and-lags/ for more
details
6. Attributes Of A Project Activity/Task
Designed and Developed by Praveen Malik, PMP
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Activity Name
Duration (D) – Number of time units required to finish an activity
Early Dates
Early Start (ES) – An activity can start as early as this date
Early Finish (EF) – An activity can finish as early as this date
Details in next few slides
Late Dates
Late Start (LS) – An activity can start as late as this date without delaying the project
Late Finish (LF) – An activity can start as late as this date without delaying the project
Details in next few slides
Float/Slack
defined on slide #24
Refer to https://www.pmbypm.com/total-float-vs-free-float/ for more details
7. Sample Project
Designed and Developed by Praveen Malik, PMP
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Activity Name Duration(Days) Predecessor
A 3 Project Start
B 4 A
C 2 B
D 4 B
E 5 Project Start
F 5 E
G 2 E
H 5 F, G
8. Network Diagram for Sample Project
Designed and Developed by Praveen Malik, PMP
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9. Forward Pass
Designed and Developed by Praveen Malik, PMP
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• Project is assumed to
start on Day 0
• Activity A would start
along with Project
Start – ES of Activity A
would be 0
• Activity A would finish
after 3 days are
elapsed – EF of A
would be 3
• EF = ES + D
10. Forward Pass
Designed and Developed by Praveen Malik, PMP
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• Activity B can start as
soon as Activity A
finishes
• ES of Activity B would
be EF of Activity A –
ES of successor
activity equals EF of
predecessor
• ESS = EFP
11. Forward Pass
Designed and Developed by Praveen Malik, PMP
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• Both Activities C & D
can start as soon as
Activity B finishes
• EF = ES + D
• ESS = EFP
13. Forward Pass
Designed and Developed by Praveen Malik, PMP
13
• Activity H can start only
after both Activities F& G
finish
• Activity G finishes last so
Activity H would start on
Day 10
• ESS = Max(EFP)
14. Project Duration
Designed and Developed by Praveen Malik, PMP
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• Project can finish only
after all three Activities
C, D & H finish
• Activity H finishes last
so project duration
would be 15 days
• Project Duration =
Max(EF)
15. Backward Pass
Designed and Developed by Praveen Malik, PMP
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• Project is assumed to
finish on Day 15
• Activities C, D &H can
finish as late as Day
15 – LF of these
Activities A would be
15
16. Backward Pass
Designed and Developed by Praveen Malik, PMP
16
• Activity C can start as
late as Day 13 since it
has a Duration of 2
days and it is
supposed to be
finished by Day 15
• LS = LF - D
17. Backward Pass
Designed and Developed by Praveen Malik, PMP
17
• Activity B has to finish
before Activities C & D
can start – LF of
Activity B would be
Day 11
• LSP = Min(LFS)
20. What is Float or Slack?
Designed and Developed by Praveen Malik, PMP
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Total Float is defined as the amount of time that a schedule
activity may be delayed from its Early Start date without
delaying the project finish date
Can be calculated from the network diagram after completing the
backward pass
Indicates the amount of flexibility the project manager has to adjust
the timing of a particular activity
Calculated by subtracting Early Finish from Late Finish (or early start
from late start)
Float = LF – EF OR Float = LS - ES
22. Critical Path
Designed and Developed by Praveen Malik, PMP
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Critical Path is the longest path to complete a project
Any delay on Critical Path can lead to project delay
All the activities on Critical Path are called Critical Activities
Critical Activities have zero Float
Refer to https://www.pmbypm.com/critical-path-method-cpm-
project-management/ and https://www.pmbypm.com/critical-
path-analysis-example-0-method-1-method/ for more details