293225main 62642main 1 Pmchallenge Leach

7/28/2019 293225main 62642main 1 Pmchallenge Leach

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Larry Leach, PMP208-345-1136

[email protected]
http://www.advanced-projects.com/http://www.advanced-projects.com/


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Objectives

Identifywhy the critical chain, not the criticalpath, is often the constraint of a project

Exploit the constraint (critical chain) of a project

Subordinateeverything else to the project goal

Define buffers used in Critical Chain ProjectManagement

Exploit the multi-project constraint


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Successful Users & Clients Include

Harris Semiconductor Lucent Technologies

Honeywell DAS Israeli Aircraft Company

UA Air Force US Navy


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PHNSY-FMB Improvements

25%83110Customer Backlog 57%12.5%28.75%Overtime 22%220(99%)180(93%)

J ob CompletionRate

(same time period)

41%2,2023,741Man-Days

23%$4,700$6,113Average Cost perJ ob

(incl. overtime)

133%93%

(25 of 27)

40%

(8 of 20)

ON-TIME

(Scheduled

Availabilities)

METRIC BEFORE CCPM AFTER CCPM IMPROVEMENT


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2. Critical Chain1. Remove

resource conflicts

3. Mean Task Duration

A B C

E CB

A C D

4. Project Buffer

5. Feeding Buffer

Resource Leveled Critical (?) Path

6. Late start

Time

9. Relay racer task performance


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Goldratts Theory of Constraints

Products(or Projects)

to

Customers

Raw Materialfrom

SuppliersProductionFunctions

System Throughput Limitedby a Constraint


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The Theory of Constraints Focusing Steps

IDENTIFY constraint

EXPLOIT constraint

SUBORDINATE everything else to

the constraint Only then, ELEVATE the

constraint Do not let INERTIA prevent future

improvement


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Identify: Is the critical path the constraint?


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Resource Leveled CP


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Critical Chain Identified: The longest path through theprojectafter resource leveling.


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Example Group Result

His tog ram

0

1

2

3

4

5

6

5 10 20 30 40 50 60 70 80 MoreB in

Frequenc

y

.00%

20.00%

40.00%

60.00%

80.00%

100.00%

120.00%FrequencyC umulative %


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All Project Activity Times Are

Uncertain Estimates

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 0.5 1 1.5 2 2.5

Activity Time or Cost

P

MinimumTime/Cost

Most Likely

Time/Cost

Long tailmeans no

definite upperlimit


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Focus On Milestones And Variances Drives

Low-risk (90%+) Activity Duration Estimates

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 0.5 1 1.5 2 2.5

ScheduledDuration

CumulativeCompletion

Probability


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Critical Path Schedule HidesContingency In Each Activity

Activity 1 Activity 2 Activity 3 Activity 4 Activity 5

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 0.5 1 1.5 2 2.5

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 0.5 1 1.5 2 2.5

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 0.5 1 1.5 2 2.5

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 0.5 1 1.5 2 2.5

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 0.5 1 1.5 2 2.5


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Date-driven Human BehaviorUses Scheduled Activity Time

0

1

2

3

4

5

6

0 0.5 1 1.5 2 2.5

Act ivi ty Time or Cost

P

1 = Plan Time or Cost


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Exploit the Project Constraint

Uncertainty:

Variation in estimate

Variation in task performance

Dependent events: resources


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EXPLOIT variation by taking contingency out ofeach task, and moving it to the end of the chain.

Task 1 Task 2 Task 3 Task 4

Task 1 Task 2 Task 3 Task 4

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 0.5 1 1.5 2 2.5

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 0.5 1 1.5 2 2.5

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 0.5 1 1.5 2 2.5

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 0.5 1 1.5 2 2.5

Combining variancesCentral limit theorem


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Critical chain differs from critical

path by:Resolving resource contentionsfirst (Identify)

Using 50 % probable activity times(Exploit)

A B C

C D

(Smaller) aggregatedBuffer at end of chain

(Exploit)


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Buffer Provides AnticipatoryMeasure to Exploit Constraint

1 2 3 4 5 BUFFER

WatchWatch PlanPlan ActAct


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Buffer Tracking Predicts Action Need

Time0

1/3

2/3

1

x x

x

xx

xx

x

xx

Plan

Act

Project Buffer


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Some Applications Deploy Dynamic Buffer Threshold

Project Buffer

%Buffer

x x

x

xx

xx

x

xx

Plan

Act

RED

YELLOW

GREEN

GREEN

% Chain


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Subordinate Merging Paths WithFeeding Buffers

FB

FB

Project Buffer


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Example project as a CCPM schedule.


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Subordinate to the Critical Chain Eliminate start and stop dates for each

activity (Only start dates for chains, and endof Project Buffer!)

Late start feeding chains Intermediate milestone (hard) dates

(But...technical milestones are necessary,and there is a way to meet client orregulator demands: buffer milestone dates.)


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Critical chain task gets priority over noncritical chain task

Priority to task causing greatest projectbuffer penetration

Non-project work lowest priority


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2. Critical Chain1. Remove

resource conflicts

3. Mean Task Duration

A B C

E CB

A C D

4. Project Buffer

5. Feeding Buffer

Resource Leveled Critical (?) Path

6. Late start

Time

9. Relay racer task performance


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Resources must multi-task

Projects are late Quality deteriorates


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Task A

Task B

Task C

SwitchingInefficiency

Task A Task B Task C


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Consider Unloading Ships...

Five ships arrive. Each requires 5 person-days to unload.Each owner wants his ship unloaded ASAP. You have five

people to unload the ships. Simpleassign one to each ship.

Starting each one right away (the sooner you start)each ship is unloaded on the end of the fifth day.


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Put all five resources on ship 1 the first day, ship 2 the

second day, etc. Result:Ship New (days) Old (days) Saved1 1 5 42 2 5 3

3 3 5 24 4 5 15 5 5 0

Nobody loses. Four of five clients done sooner.Cost = $ 0


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IDENTIFY: Multi-project resourceconstraint

EXPLOIT: Prioritize projects (Drum)

SUBORDINATE: Stagger project start

ELEVATE

INERTIA

Prioritize & Sequence Projects to Accelerate Completion!


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BUFFER

Individual Project Schedules (Note resource contention)

BUFFER

Synchronized Multiple Projects Accelerate and ReduceResource Contention

BUFFER

Synchronizing (Constraint) Buffer

Constraint Resource

BUFFER

Obj i


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Objectives Identifywhy the critical chain, not the critical

path, is often the constraint of a project

Exploit the constraint (critical chain) of a project Subordinateeverything else to the project goal

Define buffers used in Critical Chain ProjectManagement

Exploit the multi-project constraint


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Implement effective process for:

Management leadership and behavior

Client alignment

Resource behavior Buffer Management

Organization specific obstacles Potential unintended consequences

Path ForwardPath Forward

F F th I f ti


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For Further Information

Leach, Lawrence P.Critical Chain Project Management

Artech House, Boston, 2000

Available from PMI Bookstore,

Amazon.com,and other major onlinebook sellers.

[email protected]. Home: 208-345-1136
mailto:[email protected]:[email protected]

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