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6. 1 Project Management Gürkan Kumbaroğlu - Bogaziçi University
Developing a Network Plan The Project Network
• The project network is developed from the information
collected for the WBS and is a graphic flowchart of the
project job plan.
– It is the tool for planning, scheduling, monitoring project progress.
• The network depicts, – project activities that must be completed;
– the logical sequences;
– the interdependencies of the activities to be completed;
– the times for the activities to start and finish;
– the longest path through the network (the critical path).
• The project network represents three quarters of the
planning process.
6. 2 Project Management
Developing a Network Plan The Project Network
• The network provides valuable information & insights:
– Planning
* Provides realistic, simple & disciplined basis for attaining objectives;
* Reduces the risk of overlooking tasks;
* Facilitates longer range and more detailed planning of projects;
* Provides a basis for scheduling labor and equipment;
* Provides an estimate for project duration;
* Indicates activities’ start/finish times and when they can be delayed;
* Provides the basis for budgeting the cash flow of the project.
– Communication
* Provides documentation & facilitates communication of project info;
* Enhances communication that melds all managers & groups together;
* Simplifies coordination at all levels of management.
Gürkan Kumbaroğlu - Bogaziçi University
6. 3 Project Management
Developing a Network Plan The Project Network
• The network provides valuable information & insights:
– Psychological
* Encourages a team feeling;
* Useful in establishing interim schedule objectives and in delineation
of responsibilities to achieve them;
– Control
* Identifies which activities should not be delayed;
* Highlights activities to consider if the project needs to be compressed
* Facilitates the application of management by exception;
* Immediately illustrates the effects of technical & procedural changes;
* Minimizes surprises.
– Training
* Useful in training new project managers and other personnel.
Gürkan Kumbaroğlu - Bogaziçi University
6. 4 Project Management
B
A
C
D
E
F
Level 1 - Milestone Plan
Level 2 - Plans
Level 3 - Plans
Developing a Network Plan From Work Package to Network
WP -1 WP -2 WP -3
Gürkan Kumbaroğlu - Bogaziçi University
6. 5 Project Management
Developing a Network Plan From Work Package to Network
Circuit
Board
Design cost
account
Production cost
account
Test cost
account
Software cost
account O r
g a
n i
z a
t i
o n
a l
U
n i
t s
Design WP D-1-1 Specifications WP D-1-2 Documentation
Production WP P-10-1 Proto 1 WP P-10-2 Final Proto 2
Test Systems WP T-13-1 Test
Software WP S-22-1 Prem Sftware WP S-22-2 Final Sftware
Lowest
Element A
D-1-1
D-1-2
B
P-1O-1
C
S-22-1
D
P-10-2
F
S-22-2
K
T-13-1
A
Spec & Docum
2
B
Proto 1
5
C
Prelim Software
3
D
Final Proto 2
4
F
Final Software
2
K
Test
3
Gürkan Kumbaroğlu - Bogaziçi University
6. 6 Project Management
• Activity: An element of the project that requires time.
• Merge Activity: An activity that has more than one activity immediately preceding it.
• Burst Activity: An activity that has more than one activity immediately following it.
• Parallel Activities: Activities that can take place concurrently.
• Path: A sequence of connected, dependent activities.
• Critical Path: It is a longest path through the network.
• Event: It is a point in time when an activity is started or completed.
• Activity-on-Node Networks: Node represents activities.
• Activity-on-Arrow Networks: Arrow represents activities.
Developing a Network Plan Constructing a Project Network
Gürkan Kumbaroğlu - Bogaziçi University
6. 7 Project Management
Basic Rules to Follow in Developing Project Networks:
1. Networks flow typically from left to right;
2. An activity cannot begin until all preceding activities have been completed;
3. Arrows indicate precedence and flow; arrows can cross over each other; their lengths and slopes are arbitrary;
4. Each activity should have a unique identification number;
5. An activity identification number must be larger than that of any activities that precede it;
6. Looping is not allowed;
7. Conditional statements are not allowed;
8. There should be a single start node and a single end node.
Developing a Network Plan Constructing a Project Network
Gürkan Kumbaroğlu - Bogaziçi University
6. 8 Project Management
Developing a Network Plan Activity-on-Node Fundamentals
A B C
Z
X
Y
L
K M
J
AA
X Z
Y
A is preceded by nothing; B is preceded by A; C is preceded by B.
Y and Z are preceded by X;
Y and Z can occur concurrently, if so desired;
X is a burst activity; Y, Z are parallel activities
J, K, L can occur concurrently, if so desired;
J, K, L must all be completed before M can begin;
M is a merge activity; J, K, L are parallel activities;
M could also be a milestone.
Z is preceded by X and Y;
AA is preceded by X and Y;
Z and AA can occur concurrently, if so desired.
Gürkan Kumbaroğlu - Bogaziçi University
6. 9 Project Management
Developing a Network Plan Activity-on-Node Fundamentals
KOLL Business Center - Network Information
Activity Description Preceding Activity Activity Duration
A Application approval None 5 B Construction plans A 15 C Traffic study A 10 D Service availability check A 5 E Staff report B, C 15 F Commission approval B, C, D 10 G Wait for construction F 170 H Occupancy E, G 35
Gürkan Kumbaroğlu - Bogaziçi University
A
Application approval
B
Construction plans
C
Traffic Study
D
Service avail check
E
Staff report
F
Commission approval
G
Wait construction
H
Occupancy
6. 10 Project Management
Developing a Network Plan Network Computation Process
• Forward Pass—Earliest Times
– How soon can the activity start? (early start—ES)
– How soon can the activity finish? (early finish—EF)
– How soon can the project finish? (expected time—ET)
• Backward Pass—Latest Times
– How late can the activity start? (late start—LS)
– How late can the activity finish? (late finish—LF)
– Which activities represent the critical path?
– How long can it be delayed? (slack or float—SL)
Gürkan Kumbaroğlu - Bogaziçi University
6. 11 Project Management
Developing a Network Plan Network Computation Process
Forward Pass Computations
• Add activity times along each path in the network
(ES + Duration = EF).
• Carry the early finish (EF) to the next activity where
it becomes its early start (ES) unless…
• The next succeeding activity is a merge activity, in
which case the largest EF of all preceding activities
is selected.
Gürkan Kumbaroğlu - Bogaziçi University
6. 12 Project Management
Developing a Network Plan Network Computation Process
Applictn approval
0 A 5
5
Construct plans
5 B 20
15
Traffic study
5 C 15
10
Commisn approval
20 F 30
10
Wait constructn
30 G 200
170
Staff report
20 E 35
15
Occpancy
200 H
235
35
Service check
5 D
10
5
Description SL
ES ID EF
LS Dur LF
Legend
Forward Pass Computations
Gürkan Kumbaroğlu - Bogaziçi University
6. 13 Project Management
Backward Pass Computations
Developing a Network Plan Network Computation Process
• Subtract activity times along each path in the
network (LF - Duration = LS).
• Carry the late start (LS) to the next activity where it
becomes its late finish (LF) unless
• The next succeeding activity is a burst activity, in
which case the smallest LF of all preceding activities
is selected.
Gürkan Kumbaroğlu - Bogaziçi University
6. 14 Project Management
Applictn approval
0
0 A 5
0 5
5
Construct plans
0
5 B 20
5 15 20
Traffic study
5
5 C 15
10 10
20
Commisn approval
0
20 F 30
20 10 30
Wait constructn
0
30 G 200
30 170 200
Staff report
165
20 E 35
185 15
200
Occpancy
0
200 H
235
200 35 235
Service check
10
5 D
10
15 5 20 Description SL
ES ID EF
LS Dur LF
Legend
Backward Pass Computations
Developing a Network Plan Network Computation Process
Gürkan Kumbaroğlu - Bogaziçi University
6. 15 Project Management
Backward Pass Computations
Developing a Network Plan Network Computation Process
• Free Slack
– The amount of time an activity can be delayed without
delaying any immediately following (successor) activity.
• Total Slack (or just Slack)
– The amount of time an activity can be delayed without
delaying the entire project.
• The critical path is the network path(s) that has
(have) the least slack in common.
Gürkan Kumbaroğlu - Bogaziçi University
6. 16 Project Management
Applictn approval
15
0 A 5
15 5
20
Construct plans
15
5 B 20
20 15 35
Traffic study
20
5 C 10
25 10
35
Commisn approval
15
20 F 30
35 10 45
Wait constructn
15
30 G 200
45 170 215
Staff report
180
20 E 35
200 15
215
Occpancy
15
200 H
235
215 35 250
Service check
25
5 D
10
30 5 35 Description SL
ES ID EF
LS Dur LF
Legend
Externally Imposed Deadline > Expected Completion Time
Developing a Network Plan Network Computation Process
Gürkan Kumbaroğlu - Bogaziçi University
6. 17 Project Management
Applictn approval
- 5
0 A 5
- 5 5
0
Construct plans
- 5
5 B 20
0 15 15
Traffic study
0
5 C 10
5 10
15
Commisn approval
- 5
20 F 30
15 10 25
Wait constructn
- 5
30 G 200
25 170 195
Staff report
160
20 E 35
180 15
195
Occpancy
- 5
200 H
235
195 35 230
Service check
5
5 D
10
10 5 15 Description SL
ES ID EF
LS Dur LF
Legend
Externally Imposed Deadline < Expected Completion Time
Developing a Network Plan Network Computation Process
Gürkan Kumbaroğlu - Bogaziçi University
6. 18 Project Management
• Network Logic Errors – Conditional statements;
– Looping.
• Activity Numbering: Each activity needs a unique ID code.
• Use of Computers – Computations, Data storage and updating, Network development
• Calendar Dates – Ultimately they must be deployed;
– Most computer programs will do it automatically.
• Multiple start and/or end activities – Some computer programs require a common start and finish;
– Dangler paths are confusing at best;
– Dangler paths can be avoided by defining specific start, finish
nodes.
Developing a Network Plan
Gürkan Kumbaroğlu - Bogaziçi University
6. 19 Project Management
Developing a Network Plan Gantt Charts
15
10
5
10
5
170
35
5
50 100 150 200 235
Application approval
Construction plans
Traffic study
Service check
Staff report
Commission approval
Wait for construction
Occupancy
Gantt Chart of the Koll Business Center Project
(where every activity is scheduled to start at its earliest start time)
Gürkan Kumbaroğlu - Bogaziçi University
6. 20 Project Management
Developing a Network Plan Extended Network Techniques
B1
Lay Pipe 1/3
A1
Trench 1/3
A2
Trench 1/3
A3
Trench 1/3
B2
Lay Pipe 1/3
B3
Lay Pipe 1/3
C1
Refill 1/3
C2
Refill 1/3
C3
Refill 1/3
Example of Laddering Using Finish-to-Start Relationships (a pipe laying project)
Gürkan Kumbaroğlu - Bogaziçi University
6. 21 Project Management
A Lag is the minimum amount of time a dependent activity must be
delayed to begin or to end.
• Finish-to-Start Relationships offer the ability to delay the next
activity in a sequence even when the preceding activity is completed.
Developing a Network Plan Extended Network Techniques
X Y
Finish-to-Start
Relationship
Lag 2
Gürkan Kumbaroğlu - Bogaziçi University
e.g. it takes two days for transport
6. 22 Project Management
• Start-to-Start Relationship typically depicts a situation in which a
portion of one activity is performed and the successor activity is
initiated before completing the first.
Developing a Network Plan Extended Network Techniques
Trench
1 mile
Lay pipe 1 mile
Lag 3
Start-to-Start
Relationship
Gürkan Kumbaroğlu - Bogaziçi University
6. 23 Project Management
• Finish-to-Finish Relationship is used when the finish of one activity
depends on the finish of another activity.
Developing a Network Plan Extended Network Techniques
Prototype
Testing
Lag 4
Finish-to-Finish
Relationship
Gürkan Kumbaroğlu - Bogaziçi University
6. 24 Project Management
• Start-to-Finish Relationship is used when the finish of one activity
depends on the start of another activity.
Developing a Network Plan Extended Network Techniques
Testing
System document
Lag 3
Start-to-Finish
Relationship
Gürkan Kumbaroğlu - Bogaziçi University
6. 25 Project Management
Developing a Network Plan Extended Techniques Example
Legend
Lag 10
Lag 5
Lag 5
Lag 10
Lag 10
ES ID EF
SL SL
LS LF Dur
15 C 20
5 5
20 25 5
15 E 30
0 0
15 30 15
5 B 15
0 0
5 15 10
0 A 5
0 0
0 5 5
10 D 25
11 11
21 36 15
30 F 40
0 5
30 45 10
40 H 50
5 0
45 50 5
25 G 40
11 0
36 40 4
Gürkan Kumbaroğlu - Bogaziçi University
6. 26 Project Management
Wind Energy Plan Project Activity Durations and Precedence Relationships
Gürkan Kumbaroğlu - Bogaziçi University
6. 27 Project Management
Wind Energy Plan Project The Project Network
2
A
C
G
E
D
L
K
H
F
I
J
M
N
Start
B
Finish
2
1
Gürkan Kumbaroğlu - Bogaziçi University
6. 28 Project Management
Wind Energy Plan Project The Project Network
Activity Duration Early Early Late Late Slack
Code (month) Start Finish Start Finish
A 2 0 2 0 2 0
B 12 0 12 0 12 0
C 2 0 2 0 2 0
D 2 2 4 2 4 0
E 4 2 6 3 7 1
F 4 4 8 4 8 0
G 3 2 5 4 7 2
H 5 4 9 5 10 1
I 3 5 8 5 10 0
J 3 7 10 7 10 0
K 6 2 8 5 11 3
L 9 2 11 2 11 0
M 1 10 11 10 11 0
N 1 11 12 11 12 0
Gürkan Kumbaroğlu - Bogaziçi University
6. 29 Project Management
Wind Energy Plan Project The Gantt Chart
Activity Time Plan (months)
Code 1 2 3 4 5 6 7 8 9 10 11 12
A
B
C
D
E
F
G
H
I
J
K
L
M
N
Gürkan Kumbaroğlu - Bogaziçi University
6. 30 Project Management
Air Control Project The Project Plan
Gürkan Kumbaroğlu - Bogaziçi University
6. 31 Project Management
Air Control Project MS Project Output
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6. 32 Project Management
Activity On Arc Rules
Gürkan Kumbaroğlu - Bogaziçi University
1. Node 1 represents the start of the project. An arc should lead from node 1
to represent each activity that has no predecessors
2. A finish node representing the completion of activities should be included
3. Nodes should be numbered successively
4. An activity should not be represented by more than one arc in the network
5. Two nodes can be connected by at most one arc
6. 33 Project Management
Activity On Arc Example
Gürkan Kumbaroğlu - Bogaziçi University
Activity Predecessors Duration (days)
A - 6
B - 9
C A, B 8
D A, B 7
E D 10
F C, E 12
ET(i): Early event time; earliest time at which the event corresponding to node i can occur
LT(i): Late event time; latest time at which the event corresponding to node i can occur
TS(i,j) = LT(j) – ET(i) – dij
FS(i,j) = ET(j) – ET(i) – dij
6. 34 Project Management
References:
• Larson E. W and Gray C. F., “Project Management: The
Managerial Process”, 5th ed. Mc Graw Hill/Irwin, NY, USA, 2011
• Winston, L.W., “Operations Research: Applications and
Algorithms” 4th ed. Duxbury Press, 2003.
• Original slides courtesy of Prof. Ilhan Or.
Gürkan Kumbaroğlu - Bogaziçi University