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ELC 347 project management

Week 12

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Agenda

• Integrative Project – 4th part due – Outline of deliverables (posted in WebCT)

• Quiz 2 Corrected– More effort wouldn’t hurt

• Today we will discuss Critical Chain Project Scheduling

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Schedule for the final few Days

• Nov 28– Assignment 5 due

• Nov 30– IP part 5 due– Discussion on resource Leveling (Chap 12)

• Dec 7– IP part 6 Due (will be corrected and returned within 24 hours)– Quiz 3 Assigned (Chap 10, 11, 12, & 13)– Discussion on Project Evaluation and Control (chap 13)

• Dec 8 @ Midnight– Resubmission of IP part 1 – 5 deadline

• Dec 11 @ 10 AM– IP project (complete) due – Resubmission of Part 6 – IP project Presentation

• Dec 15 @ noon– Quiz 3 Due

• One less quiz and 2 less assignments then was identified in syllabus

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Course Grading Rubric

Exams (3 @ 12% each) 36%

Assignments (5 @ 7% each) 35%

IP Project 19%

Pre-professional Conduct 10%

Total 100%

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Critical Chain Project Scheduling

Chapter 11

© 2007 Pearson Education

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BAE Systems

http://www.baesystems.com/

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Theory of Constraints & Critical Chain Project Scheduling

A constraint limits system output.The Goal – Goldratt

TOC Methodology1. Identify the constraint2. Exploit the constraint3. Subordinate the system4. Elevate the constraint5. Repeat the process

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Dr J Edwards Deming

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VariationCommon Cause

Inherent in the systemSpecial Cause

Due to a special circumstance

Managers should• Understand the difference between the two

• Not adjust the process if variation is common cause

• Not include special cause variation in risk simulation

• Not aggregate discrete project risks

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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

time

25%

50%

80%90%

Gaussian Distribution

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Wasting Extra Safety Margin

1. The Student Syndromea. Immediate deadlinesb. Padded estimatesc. High demand

2. Failure to pass along positive variationa. Other tasksb. Overestimation penaltyc. Perfectionism

3. Multitasking4. Path Merging

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Critical Chain Solutions

Central Limit Theorem

Standard deviation of the sum is less than the sum of the

standard deviations!

Aggregating risk leads to reduced risk

Activity durations estimated at 50% level

Buffer reapplied at project level– Goldratt rule of thumb (50%)– Newbold formula (2σ)

Feeder buffers for non-critical paths

n

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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

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Critical Chain Solutions

Bob

Feeder Buffer

Feeder Buffer

Feeder Buffer

ProjectBufferBob

Bob

Buffers protect constraints and prevent delays

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Critical Chain Project Portfolios

Drum – system-wide constraint that sets the beat for the firm’s throughput

• Drum – person, department, policy, resource

• Capacity constraint buffer – safety margin between projects

• Drum buffer – extra safety before the constraint

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Applying CCPM to Project Portfolios

1. Identify the drum

2. Exploit the druma. 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

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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

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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

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Problems on 373

• Assignment 5– Problems 1,2,3 4 & 5 on page 373 & 373

• Pert to CCPM– Figure total Duration– Take 50% activity duration

• Figure new total duration– Project buffer = 50%(old –new)

– If you have non critical path critical• Change to Late start • Feeder buffer is 50% of slack on non –critical path