CPM-200B Critical Path Scheduling Techniques, Jim Wrisley

0Copyright 2001 All Rights Reserved

Performance Management Associates, Inc. Project Scheduling

CPMCPM--200: Principles of Schedule 200: Principles of Schedule ManagementManagement

IPM 2002 Fall ConferenceIPM 2002 Fall ConferencePMIPMI--College of Performance Management College of Performance Management Professional Education ProgramProfessional Education Program

Lesson B: Critical Path Scheduling TechniquesLesson B: Critical Path Scheduling Techniques

InstructorInstructor

Jim WrisleyJim Wrisley



Lesson Objectives Lesson Objectives -- 11TLO #1: The student will understand the evolution

of network scheduling, be able to differentiate between two (2) primary types of network scheduling methods and understand the value of resource loading the network.

ELO #1: The student will recognize the evolution of PERT Scheduling.

ELO #2: The student will be able to recognize and the PrecedenceDiagramming Method (PDM) type schedule.

ELO #3: The student will recognize the value of resource loading a schedule.



Lesson Objective Lesson Objective -- 22TLO #2: The student will understand how to create

and analyze a PDM type schedule. ELO #1: The student will be able to recognize and use the PERT

Formula for calculating durations. ELO #2: The student will be able to define the use of : Finish-to-Start,

Start-to-Start, Finish-to-Finish, relationships. ELO #3: The student will be able to define and calculate: critical path,

and total float on a PDM Schedule.



Lesson OutlineLesson Outline

Reviewing History of Network Scheduling PERT Durations Present Three Major Types of Network

Schedule Estimating Techniques and Associated Terminologies

Demonstrate Network Computations Discuss the Importance of Resource Leveling Discussion



Network Scheduling



The History of Network SchedulingPERT Scheduling

U.S. Navy Special Projects Office

Polaris Missile Program 1957

- Activity-on-Node (AON) also known as Precedence Diagramming Method (PDM) --- Most PopularMost Popular- Activity-on-Arrow (AOA) also known as Arrow Diagramming Method (ADM)

Critical Path Method Remington-Rand and

Dupont Chemical processing 1957



Critical Path Method (CPM) Estimating Method

An Activity receives a Single Point Estimate instead of the 3 required by PERT. Hence no formula is needed.

Example: Estimated Duration = 17 days



Program Evaluation Review Techniques (PERT) Estimating Method

The PERT FormulaUses a 3 Point Estimate

PPessimistic + 4xMMost Likely + OOptimistic

6

Given:P = 22 daysM= 17 daysO = 15 days

22 + 68 + 15 105

6 6= = 17.5



Monte Carlo Simulations Estimating Method

Monte Carlo Simulations uses PERTs 3 Point Estimates as basis. But it does not use the PERT formula.This statistical techniqueutilizes a computer to simulate the outcome of a project. It will give you the probability of completing the project on any given day!



Pros and Cons of Estimating MethodsCPM: Easiest to use. Many experts believe it is the least accurate predictor.PERT: More sophisticated and requires more thought. Many experts believe it is more accurate than CPM.Monte Carlo Simulations: Most sophisticated. Many experts believe it is the best prediction technique



Basic Scheduling TermsCritical Path: Longest path through Project. Has no slack.Slack (Float): The amount of time an activity can be delayed without delaying the project.Lag: Inserted waiting time between tasks.Estimating Methods: (CPM, PERT, Monte Carlo)Resource Leveling: Allows a more stable number of resources to be used on the project.Crashing The Schedule: Adding more resources to the Critical PathFast Tracking: Doing more tasks in parallel.



The Goals Of Project Management:to make the most effective use of available resources such as:

so that project objectives and goals can be achieved:

People Equipment Facilities Materials Money Technology

Within budget On schedule To the desired quality



Work Packages / Activities

CONTROL ACCOUNT

WBS

WORKPACKAGES

ACTIVITIES



CALCULATING THE NETWORK

Task Durations Forward Pass Backward Pass



Task Durations (Estimates)

Developed for each activity Developed by best

available authority Generally assumes normal

conditions (manpower, equipment, calendar, etc.)

CAUTION: - Over-Estimating Tendencies



DURATIONDRIVEN

EFFORTDRIVEN

Activity Types

Estimate based on amount of calendar time necessary for task completion

Estimate based on the amount of work required to complete the activity



PDM Network - A

PROJECT LENGTH?

M/S

0

ProjectStart

3B

10E

4A

3D

C4

F8

G6

M10

ProjectCompleted0

M/S

4H

5L

4K

3J

2I



EARLY DATES

Forward Pass From project start to finish, calculate the earliest

that each activity can start and finish according to the logical sequence of work and the duration of each activity

Yields project duration



PDM Network - A

FORWARD PASS

M/S

0

1 0000

ProjectStart

3

1 3002

B10

4 13005

E

4

1 4001

A3

5 7004

D

1 4003

C4

12006

F8

5 19007G

6

14 29013M

10

20

29014

ProjectCompleted0

30 M/S

4

14 17008

H5

18 22012

L

4

19 22011

K3

16 18010

J2

14 15009

I



LATE DATES

Backward Pass Working backward from project finish to start,

calculate the latest that each task must start and finish in order to meet the end date.

Yields when the project must start to meet the latest acceptable completion date.



PDM Network - A

BACKWARD PASS

M/S

0

1 0000

ProjectStart

3

1 3002

B10

4 13005

E

4

1 4001

A3

5 7004

D

1 4003

C4

12006

F8

5 19007G

6

14 29013M

10

20

29014

ProjectCompleted0

30 M/S

4

14 17008

H5

18 22012

L

4

19 22011

K3

16 18010

J2

14 15009

I

1 0 1 3 4 13

14 17 18 20

2 5 136 1914 2920

2930

21 24 25 29

26 2923 2521 22



Why Calculate The Network?

Establish ES & EF dates and project duration Calculate LF & LS dates based on project completion Defines Float



= 13 days "Float"

Also called Total/Path/Shared Float

Float(Leeway Or Slack)

Amount of time an activity can be delayed before it impacts Project Completion

Calculated by comparing LF to EF

001A

4

1 4

1714



Total Float

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

LF

EFES

LS

A

Total Float for Activity A

A



3

D

5 7

H

14 17

4

6 days "Free Float"

004 008

Activity (Free) Float Amount of time an activity can be delayed before

it impacts any succeeding activity



PDM Network - A

M/S

0

1 0000

ProjectStart

3

1 3002

B10

4 13005

E

4

1 4001

A3

5 7004

D

1 4003

C4

12006

F8

5 19007G

6

14 29013M

10

20

29014

ProjectCompleted0

30 M/S

4

14 17008

H5

18 22012

L

4

19 22011

K3

16 18010

J2

14 15009

I

Critical Path

1 0 1 3 4 13

14 17 18 20

2 5 136 1914 2920

2930

21 24 25 29

26 2923 2521 22



Critical Path

Longest path of logically related activities through the network which has the least Total Float.

Defines project duration. Path:

B E G M3 10 6 10+ + + = 29 days



Resource Leveling



Assignment of resources (people, equipment, facilities, materials, etc.) to each activity within the project

Comparison of Needs vs. Availability Resulting Profiles (Histograms) Cumulative Plots (S-Curves) Other descriptive terms:

Resource Allocation Resource Leveling Resource Scheduling Resource Smoothing

Why We Resource Load Networks



This OFTEN is not true

The availability of resources has a direct bearing on the duration of each activity.

We Develop A Staffing Plan Because...

During Critical Path Method (CPM) schedule development, the assumption has been that unlimited manpower, material and equipment are available



CONTROL ACCOUNT

$ $ $

$ $$ $$$

$$$

Total $1 $1 $2 $1 $2 $2 $2 $1 $1

$

Manual?

Automated?

Hrs Hrs Hrs

Hrs Hrs

Hrs Hrs

Hrs



Resources-loaded Schedules Schedules that have required resources identified

to a specific schedule activity

ACTIVITY X

DURATION: 2 daysTF = 1

Resources: 1 Hydrogeologist1 Hydrogeologist Assistant32 Hours

TITLE:

EARLYSTART

LATESTART

EARLYFINISH

LATEFINISH

Review Geology Report

4/1

4/2

4/2

4/3



PDM Network - A

M/S

0

000ProjectStart

3

002

B10

005

E

4

001

A3

004

D

003

C4

006

F8

007G

6

013M

10

014Project

Completed0

M/S

4

008

H5

012

L

4

011

K3

010

J2

009

I

1 May 4 May

18 May 23 May

1 May 3 May

1 May 3 May

1 May 4 May

2 May 7 May

7 May 9 May

24 May 29 May

4 May 17 May

4 May 17 May

7 May 16 May

8 May 17 May

18 May 23 May

30 May 4 Jun

18 May 21 May

30 May 31 May

18 May 25 May

18 May 25 May

22 May 24 May

1 Jun 5 Jun

24 May 31 May

5 Jun 11 Jun

25 May 31 May

6 Jun 11 Jun

29 May 11 Jun

29 May 11 Jun

11 Jun1 May



Activity Duration Total Float Free Float Resources

*Duration Driven

ABCDEFGH*IJKLM

434310864234510

1301

13010777770

0006010000770

246

123

4016304

14188

2020

215

Network A



Activity

A

B

C

D

E

F

G

H

I

J

K

L

M

1

6

2

3

11

2

6

2

3

11

3

6

2

3

11

4

6

3

4

13

7

1

4

2

7

8

1

4

2

7

9

1

4

2

7

10

4

2

6

11

4

2

6

14

4

2

6

15

4

2

6

16

4

2

6

17

4

4

18

5

1

7

13

21

5

1

7

13

22

5

1

6

12

23

5

1

6

12

24

5

6

4

15

25

5

2

4

11

29

2

4

2

8

30

2

4

2

8

31

2

4

2

8

1

2

2

4

2

2

5

2

2

6

2

2

7

2

2

8

2

2

11

2

2

( = Late Finish)

May June



0

2

4

6

8

10

12

14

16

R

e

s

o

u

r

c

e

R

e

q

u

i

r

e

m

e

n

t

s

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29

Project Days

Total Resources by Day - Net ANet A Resource Profile



Why We Do Resource Analysis

Determine resource requirements (manpower projections, hire/fire strategies)

Balance resource usage Consider time/resource tradeoff



Total Float

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

LF

EFES

LS

A

Total Float for Activity A

A



Activity

A

B

C

D

E

F

G

H

I

J

K

L

M

1

6

2

3

11

2

6

2

3

11

3

6

2

3

11

4

6

3

4

13

7

1

4

2

7

8

1

4

2

7

9

1

4

2

7

10

4

2

6

11

4

2

6

14

4

2

6

15

4

2

6

16

4

2

6

17

4

4

18

5

1

7

13

21

5

1

7

13

22

5

1

6

12

23

5

1

6

12

24

5

6

4

15

25

5

2

4

11

29

2

4

2

8

30

2

4

2

8

31

2

4

2

8

1

2

2

4

2

2

5

2

2

6

2

2

7

2

2

8

2

2

11

2

2

( = Late Finish)

May June



PDM Network - A

M/S

0

1 0000

ProjectStart

3

1 3002

B10

4 13005

E

4

1 4001

A3

5 7004

D

1 4003

C4

12006

F8

5 19007G

6

14 29013M

10

20

29014

ProjectCompleted0

30 M/S

4

14 17008

H5

18 22012

L

4

19 22011

K3

16 18010

J2

14 15009

I

Critical Path

1 0 1 3 4 13

14 17 18 20

2 5 136 1914 2920

2930

21 24 25 29

26 2923 2521 22



Activity

A

B

C

D

E

F

G

H

I

J

K

L

M

1

6

2

3

11

5

2

6

2

3

11

5

3

6

2

3

11

5

4

6

3

4

13

7

7

1

4

2

7

6

8

1

4

2

7

6

9

1

4

2

7

6

10

4

2

6

11

6

4

2

6

12

14

6

4

2

6

12

15

6

4

2

6

12

16

6

4

2

6

12

17

1

4

4

5

18

1

5

1

7

13

14

6

21

1

5

1

7

13

14

6

22

5

1

7

6

12

13

23

5

1

7

6

12

13

24

5

1

6

4

15

12

25

5

1

6

2

4

11

12

29

6

2

4

2

8

12

30

2

4

2

8

31

2

4

2

8

1

2

4

2

2

8

4

2

4

2

2

8

5

2

2

6

2

2

7

2

2

8

2

2

11

2

2

Total Float

13

0

1

13

0

1

0

7

7

7

7

7

0

5

5

5

5

5

5

5

LOGIC A "DRIVES" D

D "DRIVES"

H - L - I - J - K

( = Late Finish)

May June



0

2

4

6

8

10

12

14

R

e

s

o

u

r

c

e

R

e

q

u

i

r

e

m

e

n

t

s

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29

Project Days

"Net A" Resource Profile



S Curves

RESOURCES

TIME

TIME-PHASED RESOURCE PLAN(CUMULATIVE PLOT)



( = Late Finish)

May June

Activity

A

B

C

D

E

F

G

H

I

J

K

L

M

1

6

2

3

11

2

6

2

3

11

3

6

2

3

11

4

6

3

4

13

7

1

4

2

7

8

1

4

2

7

9

1

4

2

7

10

4

2

6

11

4

2

6

14

4

2

6

15

4

2

6

16

4

2

6

17

4

4

18

5

1

7

13

21

5

1

7

13

22

5

1

6

12

23

5

1

6

12

24

5

6

4

15

25

5

2

4

11

29

2

4

2

8

30

2

4

2

8

31

2

4

2

8

1

2

2

4

2

2

5

2

2

6

2

2

7

2

2

8

2

2

11

2

2



"Net A" Resource Curves

0

25

50

75

100

125

150

175

200

225

250

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29

Project Days

C

u

m

u

l

a

t

i

v

e

R

e

s

o

u

r

c

e

s

Early StartLate StartScheduled (Baseline)



FORECASTING RESOURCES2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

1 2 4 6

5

3

A

B

C

D

E F

G

HTOTAL CUM

1 1 1 1

1 1 1 1 1

1 1 1 1 1 1

1 1 1 1 1 1

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

1 1 1

1 1 1 1 1 1 1 1 1 1

1 1 1 11 1 1 1 3 3 3 3 3 2 2 2 2 2 2 2 1 1 1 1 2 2 2 2 2 2 2 2 1 11 2 3 4 7 10 13 16 19 21 23 25 27 29 31 3334 35 36 37 39 41 43 45 47 49 51 5354 55

A4

E 16

G 10

F 4

H 4B

5C 6

D 6

RESOURCES3 2 1

TIME PROFILE

USAGE TABLE

CUMULATIVE (S) CURVE

RESOURCES

5040

2030

10

1



Should I Resource Load MySchedule?

Pros: Tight integration of schedules and budgets Visibility of resource requirements by skill category Facilitates enterprise-wide resource planning Ease of what if modeling during the planning phase Facilitates recovery planning

Cons: Requires expert scheduling capabilities (software & personnel) Over reliance on software tools instead of resource managers Some resources are more critical than others Benefits diminished if not done on an enterprise-wide basis



Planning & BudgetingEstablish the Baseline - An Iterative 3-Step Process

$

Time

Mgmt Res

Baseline

1. Define The Work

2. Schedule The Work

3. Allocate Resources

Project Budget Base

1525

3030

10040

60



Additional Reading Resources

Scheduling Guide for Program Managers: Defense Acquisition University - 2001A Guide To Project Management Body of Knowledge: Project Management Institute- 2000 PMP Exam Prep- 2nd Edition: Rita Mulcahy, PMP



CD-ROM Table of ContentsSearchHelpPractice SymposiaImplementing DOE Complex-Wide EVMSProject Management ThisValue Added with Weekly Earned ValueEarned Value and Program Independent AssessmentsOTB - The Simple Solution to all your "Insufficient Budget" Available ProblemsEVM as the Main Driver for Integrating Project ManagementThe Relationship Between Cost Growth and Schedule GrowthOvercoming Risk Management Challenges in a Teaming EnvironmentWhy we need Weekly Earned Value Trend DataImproving the Effectiveness of PMO by Integrating Knowledge Management ConceptsThe Integrated Master Plan (IMP)/Integrated Master Schedule (IMS)EVM and Test Software Development ProjectsControlling the Type 45 Destroyer ProgrammeRaytheon's Earned Value Computer Based Training (CBT)Working with Suppliers and EVMValue Added with EVM and the OTBEVM at Scientific Labs: How to Avoid High Profile DisastersIMP/IMS Development - An Integrated ApproachEVMS - Subcontractor IntegrationValue Added with EVM Metrics for Award FeeValue Added with EVM for Senior Level Portfolio ManagementEVMS CONOPS - Partners in Excellence with our CustomersAdaptive Enterprises - PM in a Volatile EnvironmentDevelopment & Deployment of an EVM ToolIs There Value to an Earned Value Metric?Minimize the Level-Of-Effort (LOE) Component for Engineering LaborGetting Full Value from Earned Value with Relationship-Objective Analysis

Tool DemonstrationsPerforming Weekly Earned Value Successfully with MPM 3.0Integrated EVM Systems Developed for a Multi-Laboratory International

Topical WorkshopsTraining SeminarsCPM100: Principles of Project ManagementIntegration and Scope ManagementTime and Cost ManagementQuality ManagementHuman Resources, Communications and Ethics MgmtRisk and Procurement ManagementPMP Review and Test Hints

CPM200: Principles of Schedule ManagementIntroduction to Scheduling TechniquesCritical Path Scheduling TechniquesSchedule Analysis TechniquesEV Schedule Performance vs. Time Based SchedulingIntroduction to Schedule Risk AssessmentEnterprise Wide Scheduling

CPM300: Principles of Earned Value ManagementEVM Principles and TerminologyInterpreting EVM DataControl System Design, Part 1Control System Design, Part 2Developing the PMBUse of EVM by Decision Makers

CPM400: Principles of Earned Value Metrics and AnalysisMaintaining the PMBEarned Value Data Analysis Techniques, Part 1Earned Value Data Analysis Techniques, Part 2Calculating Estimates at CompletionImpact of PMB Stability on EAC CalculationsFunds Management and the CFSR

CPM500: Principles of Technical ManagementDevelopment of the WBSThe Role of Systems EngineeringThe Use of the IPT in Project ManagementImplementing Technical Performance MeasurementManaging Quality on the ProjectTechnical Risk Management

CPM600: Principles of Project IntegrationIntegrating the Project's Technical ComponentsIMP and its Impacts on IMSIntegrating Scheduling and EVM MetricsIntegrating Risk into PMB DevelopmentProject Integration Case Study: Buyer's PerspectiveProject Integration Case Study: Seller's Perspective

Documents

CPM-200B Critical Path Scheduling Techniques, Jim Wrisley