Critical Chain

1
Critical Chain
2
PMBOK Definition

• Critical chain
• Schedule network analysis technique that modifies
  the schedule to account for limited resources.
• Both deterministic and probabilistic techniques
• Build schedule based on non-conservative
  estimates for activity durations
• Focus is on managing buffer activity durations
  instead of slack

3
Why do projects fail?

• Goldratts answer
• Parkinsons law work fills the time available
  why make added effort to complete a task today
  that isnt due until tomorrow.
• Self-protection if finish early then will be
  given less time next time
• Dropped baton early finish may not lead to an
  early start of the next activity if people arent
  ready to start (or dont received the signal to
  start)
• Excessive multitasking
• Resource bottlenecks
• Student syndrome delay the start of tasks until
  you absolutely have to

4
(No Transcript)
5
(No Transcript)
6
(No Transcript)
7
(No Transcript)
8
(No Transcript)
9
(No Transcript)
10
(No Transcript)
11
(No Transcript)
12
(No Transcript)
13
(No Transcript)
14
(No Transcript)
15
What is a critical chain?

• Two types of dependencies
• Technical or task dependency
• Resource dependency
• Critical chain is the longest string (or chain)
  of dependencies
• Critical chain is the resource-constrained
  critical path

16
Critical chain process

• Aggressively estimate activities with 50/50
  chance of completion
• Find the critical chain
• Add project buffer at the end of the project.
• Add feeder buffers where non-critical paths merge
  with the critical chain
• Add resource buffers
• Schedule non-critical activities at their latest
  start

17
Two types of Resource Buffers

• Resource Time buffer to ensure that the critical
  resource is on-call and available when needed
• Resource Bottleneck buffer just before any
  activities that require the project bottleneck.

18
Air Control ProjectCritical Path Network
8-2
19
Air Control Project Gantt Chart
8-3
20
Air-control project - Resources
Rob
Carly
Ryan
Lauren
Connor
Ryan
Dawn
Kevin
Issues?
21
Air Control ProjectSchedule With Resources
Limited
8-5
22
Air Control ProjectSchedule With Resources
Limited
8-6
23
Air Control ProjectCritical Chain Network
8-8
Aggressively estimate activities with 50/50
chance of completion
24
Air Control ProjectCritical Chain Network
8-8
Find the critical chain
25
Air Control ProjectCritical Chain Network
8-8
Add project buffer at the end of the project.
26
Air Control ProjectCritical Chain Network
8-8

• Add feeder buffers where non-critical paths merge
  with the critical chain

27
Air Control ProjectCritical Chain Network
8-8
28
Air Control ProjectCritical Chain Gantt Chart
8-10

• Schedule non-critical activities at their latest
  start