INSE 6230
Total Quality Project Management
Theme 4
Project Time Management I.
Topic 2
Andrea Schiffauerova, PhD.
 Activities and sequencing
 Network diagrams
◦ AOA (Activity-on-Arrow) networks
◦ AON (Activity-on-Node) networks
 Developing a schedule
◦ Gantt Chart
INSE 6230
Total Quality Project Management
2
Network diagramming is a technique for showing the activity
precedence relationships in a project
 A network diagram is a schematic display of the logical
relationships among, or sequencing of, project activities

Activity On Arrow
network (AOA)
Activity On Node
network (AON)
1
A
0
B
C
A
2
D
3
Start
C

B
D
End
The two networks and methods are both widely used, and
both of them should be learned.
◦
Historically, CPM uses AON, PERT uses AOA
INSE 6230
Total Quality Project Management
3
Also called Arrow Diagramming Method (ADM)
 Arrows:
◦ Arrows represent particular activities
◦ Arrows show the activity sequencing
 Nodes:
◦ Nodes are the starting and ending points of activities

 Each activity is identified by a different pair of starting & ending node
 AOA network diagram can only show finish-to-start dependencies (FS)
◦ Nodes represent events, milestones, or the completion of one or a
collection of activities
 The first node signifies the start of a project, while the last node
represents its end
INSE 6230
Total Quality Project Management
4
Activity-on-Arrow (AOA) Network
INSE 6230
Total Quality Project Management
1. Find all of the activities that start at node 0. Draw their finish
nodes and draw arrows between node 0 and those finish
nodes. Put the activity letter or name and duration estimate on
the associated arrow.
2. Continue drawing the network diagram, working from left to
right. Look for bursts and merges. Bursts occur when a single
node is followed by two or more activities. A merge occurs
when two or more nodes precede a single node.
3. Continue drawing the project network diagram until all
activities that have dependencies are included on the diagram.
4. As a rule of thumb, all arrowheads should face toward the
right, and no arrows should cross on an AOA network diagram.
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Total Quality Project Management
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Example 4-3
Suppose a project consists of the five activities A, B, C, D and E that
satisfy the following relationship:
1. Neither A nor B has any immediate predecessors
2. A is an immediate predecessor of C
3. B is an immediate predecessor of D
4. C and D are immediate predecessors of E
A
1
C
E
0
3
B
2
INSE 6230
Total Quality Project Management
D
4
Example 4-3: revised
A
C
1
E
0
B
1. Neither A nor B has any immediate predecessors
2. A is an immediate predecessor of C
3’. A and B are immediate predecessors of D (revised)
4. C and D are immediate predecessors of E
A
0
C
A
2
3
D
C
1
E
P
0
3
B
2
INSE 6230
Total Quality Project Management
D
2
E
1
B
3
D
4
4
Dummy Activities in AOA Networks
Dummy activity

◦
Not a “real” activity
◦
No duration and no resources
◦
Graphically represented by a dashed line in a network
Purpose of a dummy activity

◦
Maintains the precedence relationships between activities
◦
Provides unique activity designations
Only in Activity-on-Arrow (AOA) networks!

◦
AON networks do not need dummy activities
INSE 6230
Total Quality Project Management
Dummy Activities in AOA Networks
Y
INSE 6230
Total Quality Project Management

Consider the activities associated with the fabrication of a steel
component shown in table below. Draw the Activity-on-Arrow (AOA)
network diagram for this project.
Activity
A
B
C
D
E
F
G
Precedence and durations of activities
Description
Predecessors
Preliminary design
--Evaluation of design
A
Contract negotiation
--Preparation of fabrication plant
C
Final design
B, C
Fabrication of product
D, E
Shipment of product to owner
F
INSE 6230
Total Quality Project Management
Duration
6
1
8
5
9
12
3
11
Precedence and durations of activities
Description
Predecessors
Preliminary design
--Evaluation of design
A
Contract negotiation
--Preparation of fabrication plant
C
Final design
B, C
Fabrication of product
D, E
Shipment of product to owner
F
Activity
A
B
C
D
E
F
G
A
B
1
3
E
X
0
C
F
2
INSE 6230
Total Quality Project Management
D
Duration
6
1
8
5
9
12
3
5
G
6
4
12
 Also called Precedence Diagramming Method
(PDM)
 Nodes (circles or boxes) represent activities
 Arrows represent precedence relationships
 More popular than ADM method and used by project
management software
◦ No need to use dummy activities
◦ Can show different task dependency types (FS, SS, FF, SF)
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Total Quality Project Management
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Activity-on-Node (AON) Network

INSE 6230
Total Quality Project Management
New activity nodes
representing the
beginning and the
end have been
added
AOA and AON Networks
1
A
Activity-on-Arrow
B
C
0
2
A
Activity-on-Node
INSE 6230
Total Quality Project Management
D
Start
C
3
B
D
End
AOA and AON Networks
Activity-on-Arrow
Activity-on-Node
INSE 6230
Total Quality Project Management
 Activities and sequencing
 Network diagrams
◦ AOA (Activity-on-Arrow) networks
◦ AON (Activity-on-Node) networks
 Developing a schedule
◦ Gantt Chart
INSE 6230
Total Quality Project Management
17