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Similaire à Project Management Ch11 Project Scheduling Critical Chain
Similaire à Project Management Ch11 Project Scheduling Critical Chain (20)
Project Management Ch11 Project Scheduling Critical Chain
- 2. Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 11 Learning Objectives
After completing this chapter, students will be
able to:
Understand the differences between common cause
and special cause variation in organizations.
Recognize the three ways in which project teams
inflate the amount of safety for all project tasks.
Understand the four ways in which additional project
task safety can be wasted.
11-02
- 3. Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall
Chapter 11 Learning Objectives
After completing this chapter, students will be
able to:
Distinguish between critical path and critical
chain project scheduling techniques.
Understand how critical chain methodology
resolves project resource conflicts.
Apply critical chain project management to
project priorities.
11-03
- 4. Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall
Theory of Constraints &
Critical Chain Project Scheduling
A constraint limits any system’s output.
The Goal – Goldratt
TOC Methodology
1. Identify the constraint
2. Exploit the constraint
3. Subordinate the system
4. Elevate the constraint
5. Repeat the process
11-04
- 5. FIGURE 11.2 Five Key Steps in Theory of Constraint Methodology
11-05
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
- 6. Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall
Variation
Common Cause
Inherent in the system
11-06
Special Cause
Due to a special circumstance
Managers should
• Understand the difference between the two types
• Not adjust the process if variation is common cause
• Not include special cause variation in risk simulation
• Not aggregate discrete project risks
- 7. Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall
CCPM and the Causes of Project
Delay
How safety is added to project activities
1. Individual activities overestimated
2. Project manager safety margin
3. Anticipating expected cuts from
management
11-07
time
25%
50%
80%
90%
Gaussian (lognormal)
Distribution
- 8. Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall
Wasting Extra Safety Margin
1. The Student Syndrome
a. Immediate deadlines
b. Padded estimates
c. High demand
2. Failure to pass along positive variation
a. Other tasks
b. Overestimation penalty
c. Perfectionism
3. Multitasking
4. Path Merging 11-08
- 10. Effects of Multitasking on Activity
Durations
11-10
FIGURE 11.7
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
- 11. FIGURE 11.8
Effect of Merging Multiple Activity Paths
11-11
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
- 12. Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall
Critical Chain Solutions
Central Limit Theorem
Activity durations estimated at 50% level
Buffer reapplied at project level
– Goldratt rule of thumb (50%)
– Newbold formula
Feeder buffers for non-critical paths
11-12
n
- 13. Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall
CCPM Changes
Due dates & milestones eliminated
Realistic estimates – 50% level not 90%
“No blame” culture
Subcontractor deliveries & work scheduled ES
Non critical activities scheduled LS
Factor the effects of resource contention
Critical chain usually not the critical path
Solve resource conflicts with minimal disruption
11-13
- 14. Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall
Critical Chain Solutions
11-14
Bob
Feeder
Buffer
Feeder
Buffer
Feeder
Buffer
Project
BufferBob
Bob
- 15. Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall
Critical Chain Project Portfolios
Drum – system-wide constraint that sets the
beat for the firm’s throughput
–company policy
–one person
–a department/work unit
–a resource
• Capacity constraint buffer – safety margin
between projects
• Drum buffer – extra safety before the 11-15
- 16. Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall
Applying CCPM to Project
Portfolios
1. Identify the drum
2. Exploit the drum
a. Prepare a schedule for each project
b. Determine priority for the drum
c. Create the drum schedule
3. Subordinate the project schedules (next
slide)
4. Elevate the capacity of the drum
5. Go back to step 2
11-16
- 17. Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall
Subordinating Project Schedules
Schedule projects based on drum
Designate critical chain
Insert capacity constraint buffers
Resolve any conflicts
Insert drum buffers so the constraint is not
starved
11-17
- 18. Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall
CCPM Critiques
No milestones used
Not significantly different from PERT
Unproven at the portfolio level
Anecdotal support only
Incomplete solution
Overestimation of activity duration padding
Cultural changes unattainable 11-18
- 19. Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall
Summary
Understand the differences between common cause and special
cause variation in organizations.
Recognize the three ways in which project teams inflate the amount
of safety for all project tasks.
Understand the four ways in which additional project task safety can
be wasted.
Distinguish between critical path and critical chain project
scheduling techniques.
Understand how critical chain methodology resolves project
resource conflicts.
Apply critical chain project management to project priorities.
11-19