Transcript Program Review Task Force

Project Management
OPER 576
Project Networks
Greg Magnan, Ph.D.
April 29, 2004
Level of Effort
Project Life Cycle Stages
Definition Planning
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Selection
Charter
Goals
Specs
Tasks
Responsi
bilities
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Estimates
Schedules
Sequencing
Budgets
Resources
Risks
Staffing
Execution/Impl./Control
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Status Reports
Changes
Quality
Forecasts
Closeout
 Training
 Transfer
Documents
 Release
Resources
 Lessons
Learned
II. Project Planning
7. Sequence Deliverables
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To help schedule work efficiently
Consider all WBS elements
Estimate calendar duration for each
List precedence for each task
May construct network diagram
CRITICAL PATH: longest path
through the network showing
minimum time needed
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Delays to elements on the critical path delay
the entire project!
Mascitelli: Critical Core
Activity Time Estimates
• PERT-based
• Assumptions:
– “normal” operations
– independent estimates for activities
• Optimistic / Most-likely / Pessimistic
• Formula
(O + 4M + P)/6
• Example
(10 + 4*15 + 26)/6 = 16
Early Duratio Early
Start
n
Finish
Early Duratio Early
Start
n
Finish
Task Name
Early Duratio Early
Start
n
Finish
Late
Start
Slack
Task Name
Late
Finish
Late
Start
Slack
Early Duratio Early
Start
n
Finish
Late
Finish
Task Name
Task Name
Late
Start
Slack
Late
Finish
Early Duratio Early
Start
n
Finish
Late
Start
Slack
Late
Finish
Task Name
Early Duratio Early
Start
n
Finish
Late
Start
Task Name
Late
Start
Slack
Late
Finish
Early Duratio Early
Start
n
Finish
Task Name
Late
Start
Slack
Late
Finish
Slack
Late
Finish
Project Networks
• Developed from WBS
– WBS must be deliverables-oriented!
– Activity Labeling: use WBS outline as basis
• Used for Planning, scheduling, controlling
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Activities, sequences, precedence rel’ps
Critical Path / “Crashing” network
Basis for Resource Scheduling
Communication to stakeholders
Estimate of project duration
Network Terms
• Activity
– An element in the project that consumes time, but doesn’t
necessarily require resources (e.g., approvals, contract
signing)
• “Events” do not consume time
– Can include one or more Work Packages
• Verb/noun format
• Critical path
– Path: a sequence of connected, dependent activities
– CP: Longest path through the network
• Activity-on-Node (AON) vs. Activity-on-Arc (AOA)
– AON is most commonly used (software packages)
– Nodes reflect activities
AON Network Development Rules
• Arrows indicate precedence and flow
– Flow from left to right
– Precedence determined after WBS complete
• Predecessor and Successor activities
– Preceding activities must be complete before beginning
successor activities
• Activities need labels
– Larger numbers than preceding activities
• No Looping!
– No conditional (if/then) statements
• Single Start and End nodes
Project Scheduling: Node Elements
Early Start
Duration
Early Finish
Task Name
Late Start
Slack
Late Finish
PERT Diagram
(Activity on Node)
Early Duratio Early
Start
n
Finish
Early Duratio Early
Start
n
Finish
Task Name
Early Duratio Early
Start
n
Finish
Late
Start
Task Name
Late
Slack
Finish
Late
Start
Slack
Early Duratio Early
Start
n
Finish
Late
Finish
Task Name
Task Name
Late
Start
Slack
Late
Finish
Early Duratio Early
Start
n
Finish
Task Name
Early Duratio Early
Start
n
Finish
Late
Start
Task Name
Late
Start
Slack
Late
Finish
Early Duratio Early
Start
n
Finish
Task Name
Late
Start
Slack
Late
Finish
Slack
Late
Finish
Late
Start
Slack
Late
Finish
Sample Problem
Activity
A
B
C
D
E
F
G
H
I
Duration
5
10
15
10
5
20
20
5
15
Predecessor
none
none
A
A
B
C
E
D, F, G
H
Forward & Backward Pass
• Determine:
– Early Start (ES) and Early Finish (EF)
– Late Start (LS) and Late Finish (LF)…and then Slack
• Forward Pass (EF and ES)
– For each path in the network, add activity times (duration)
to each ES to get EF (ES + Dur = EF)
– EF of preceding activity becomes ES of successor, unless
• Succeeding activity is a merge activity (>1 predecessor)
• Then select LARGEST EF time from all predecessor EF times to
become ES for successor activity
Forward & Backward Pass
• Backward Pass (LF and LS)
– Must have already completed Forward Pass
– Start with the latest EF of last activity in the network
– For each path in the network, subtract activity times
(duration) from each LF to get LS (LF - Dur = LS)
– LS of successor activity becomes LF of preceding, unless
• The next preceding activity is a burst activity (>1
successor)
• Then select SMALLEST LS time from all immediate
successor activities to determine LF time
Conclusion…
• Projects are
everywhere
• Can be actively
managed
• Science AND art