Rights Reserved 1 CPM-200: Principles of Schedule Management 15 th Annual International Integrated...

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CPM-200: Principles of CPM-200: Principles of Schedule ManagementSchedule Management

15th Annual International Integrated Program Management ConferenceNovember 16-19, Tyson’s Corner Virginia

Professional Education Program (Training Track) presented byPMI-College of Performance Management faculty

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

Instructor

L. Sue Cooper562-797-4655

[email protected]


Schedules -Foundation of EVMS

SCOPE( Technical )

Period of Performance

SCHEDULE( Time )

BUDGET / COST( Resources )

$ $

$ $

$ $

$ $

Schedules must be interrelated with scope and cost. All three pieces must be accurateto maintain an integrated baseline for successfully completing a given job.

The products/services thecontractor has agreed to

provide

The planned/actualexpenditure of

resources


Objectives The objectives of this presentation are to discuss the

– Scheduling Process• Understanding of the schedule development process and the importance

of a valid schedule– Developing a Schedule Network

• How to construct a Precedence Diagramming Method (PDM) logic network

• The different types of relationships between activities– Network Calculations

• Define the meaning of critical path• Identification of the schedule critical path• How to calculate total float and free float• The difference between total and free float

– Schedule Baseline• Understand why a baseline is necessary• Baseline change approvals

– Status Updates• Accomplishment versus forecast

– Schedule Traceability• Definitions• Importance


Schedule Topics

Scheduling Process Developing a Schedule Network Network Calculations

– Critical Path– Total Float– Free Float

Schedule Baseline Status Updates Schedule Traceability


Planning/Scheduling

Planning (Think)– Defines the activities involved in the

project, their logical sequence, and their interrelationships

Scheduling (Do it)– Places the project and each of its activities

in a workable timetable


The Scheduling Process

Define the objective – think Establish the organizational structure – think Establish the key milestones required to satisfy the objective – think Put key milestones in order of occurrence – schedule Define the activities required to accomplish the work – think Establish the logical relationships of the activities

– Calculate/analyze – schedule Estimate the duration of each activity – think Validate technical content, identify risks

– Make adjustments, as appropriate - think/schedule Commitment and approval


Importance to Program Management

Common tool for project communication

Schedule baseline development

Critical path identification/analysis

A “snapshot” of program accomplishment to date

A look ahead at the forecast of completion

Basis for EAC development

Schedule risk analysis

“What if” analysis tool


Precedence Diagramming Method (PDM)


Developing a Schedule Network

A graphical representation of a project showing interrelationships of activities

When time estimates and computations are added – become the project schedule

B C D

F G H I

AE

J


E 1011 01

Design Drawings

P 1011 01

Planning

10

Logical link to other tasks

Engineering WBS No. First Engineering task in the schedule for WBS 1011 = 01


Activities must be coded so they can be easily identified and found in the schedule database

Every activity must have– Brief description– Duration– Relationship to other activities in the schedule

Smart Codes add capability

5


A 01 a 10

Complete Staffing

10

Logical link to other tasks

IMP EventAccomplishment

Criteria


IMP example – Event A, Post Award Conference– Accomplishment 01, IPTs staffed and chartered– Criteria a, IPT Contractor/Govt Team Members

Identified– Task No., Supporting Tasks

5

Task Number

A01a 20

Identify SPO Team



– Predecessor Activity Code

– Successor Activity Code

– Relationship

Start-to-Start (SS)

Finish-to-Start (FS)

Finish-to-Finish (FF)

– Lag

All tasks must have the Predecessor/Successors identified

Design Drawings Planning Tooling

Engineering Drawing Release Complete

Predecessor Activity Successor

ER


* Finish-to-Start Finish-to-Finish

Start-to-Start

B cannot start until A finishes

B cannot finish until A finishes

B cannot start until A starts

* Most commonly used. 80-85% of the relationships in a network are FS

A B A

B

A

B

Developing a Schedule NetworkRelationship types


Let’s Create a Network

Task A initiates the project

Task A precedes tasks B, C and D

Tasks B and C precedes E

Tasks C and D precede task F

Tasks E and F precede task G

Task G completes the project

Task A


A

D

C

B

F

E

G

Let’s Build a Network


A

D

C

B

F

E

G

Determine Durations

ATPContract Complete

3

5

3

4

4

2

1

How long will each activity take to complete?


Total Float

Free Float

Project Duration

Early Dates

Late Dates

Critical Path Method



Critical Path Method

Critical Path Method (CPM)– A scheduling technique that defines all project

activities and their interrelationships

Critical Path (calculated)– Longest path of logically related activities through

the network which has the “least” Total Float– Defines project duration


Critical Path Duration = 25 Time Units

Path A-B-D-H = 19 Time Units

Path A-F-G-H = 22 Time Units

Critical Path

(25 Time Units)

Calculating the Critical Path

A3

F6

B5

G6

D4

C6

E4

H7

Add up the durations along each path to Contract Complete



Network Calculations

Forward Pass– Calculates the earliest an activity can be done based on the

logical relationships and durations– Identifies the longest path through the network which is the

‘critical path’– Every activity will have an Early Start (ES) and an Early Finish

(EF) when the forward pass is complete

Backward Pass– Calculates the latest a task can be done based on the logical

relationships and durations before affecting the end date– Every activity will have a Late Start (LS) and a Late Finish (LF)

when the backward pass is complete

To calculate the Total Float the Forward and Backward pass must be complete


ES + Duration -1 = EF

Adding activity duration to Early Start gives Early Finish

Produces

• Early Start• Early Finish

for each activity

3 3

Network Calculations–Forward Pass

ES EF

1 3 4 6


Forward Pass

A6

F9

B3

G4

D7

C5

E5

H20

Start

1

1

Start with day 1


Forward Pass

A6

F9

B3

G4

D7

C5

E5

H20

Start

1 6 7 11 12 20

21 22

1 3 4 10

4 8

11 14

Day 1 plus 6, -1 = 6 Next activity starts on the next day

Every activity has an Early Start and an Early Finish

ES EF


Network Calculations–Backward Pass

LS = LF - Duration + 1

Subtracting activity duration to Late Finish gives Late Start

Produces

• Late Start

• Late Finish for each activity

4 2

10 13 14 15

15

LS LF


Network Calculations–Backward Pass

A

6

F

9

B3

G4

D

7

C

5

E5

H

20

Start

22

22

Start with the latest Early Finish (EF)


Network Calculations–Total Float

A6

F9

B

3

G4

D

7

C

5

E

5

H

20

Start

1

226 7 11 12 20

21

7 9 10 16

12 16

17 20

22

1

6 11 12 20

21

1 3 4 10 11 14

7

4 8

Late Finish – duration + 1

The LF of the preceding activity is one day earlier


Network Calculations–Total Float

The amount of time an activity can be delayed or expanded before it impacts the project end date.

Difference between Early Finish and Late Finish calculates Float.

ES EF

30

15

30

15 45

60

15

LFLS


The amount of time an activity can be delayed or expanded before it impacts the next activity.

Difference between the early start of the next activity minus the early finish of the preceding activity (minus 1) defines free float.

DFF = 0

FFF = 0 G

7 4 10

EFF = 2

5EF = 8

ES = 11 EF = 14 154 10

4

Will occur only when multiple activities constrain a single activity.

25

Network Calculations–Free Float


Network Calculations –Total Float

A6

F9

B3

G4

D7

C

5

E5

H

20

Start

1

226 7 11 12 20

21

7 9 10 16

12 16

17 20

22

1

6 11 12 20

21

1 3 4 10 11 14

4 8

7


Is there any ‘Free Float’ in this network?

Network Calculations - Total Float

A

6

F

9

B

3

G

4

D

7

C

5

E

5

H

20

Start

1

226 7 11 12 20

21

7 9 10 16

12 16

17 20

22

1

6 11 12 20

21

1 3 4 10 11 14

TF = 0

TF = 6TF = 6TF = 6

TF = 0TF = 0TF = 0

TF = 84 8


Is there any ‘Free Float’ in this network?

Look at E & GLook At G & H

Network Calculations – Free Float

A6

F9

B3

G4

D7

C5

E5

H20

Start

1

226 7 11 12 20

21

7 9 10 16

12 16

17 20

22

1

6 11 12 20

21

1 3 4 10 11 14

TF = 0

FF = 6 TF = 6

TF = 6TF = 6

TF = 0TF = 0TF = 0

FF = 2TF = 84 8


Notice – The Critical Path is also the path with the least amount of float

Network Calculations -Total Float

A6

F9

B3

G4

D7

C5

E5

H20

Start

1

226 7 11 12 20

21

7 9 10 16

12 16

17 20

22

1

6 11 12 20

21

1 3 4 10 11 14

TF = 0

TF = 6TF = 6TF = 6

TF = 0TF = 0TF = 0

TF = 84 8


Preceding Succeeding Activity

Activity Activity Activity Duration Start Complete

A B, F 3 Apr 1 Apr 5

B A C, D 5 Apr 6 Apr 10

C B E 6 Apr 11 Apr 16

D B H 4 Apr 11 Apr 14

E C H 4 Apr 17 Apr 20

F A G 6 Apr 6 Apr 11

G F H 6 Apr 12 Apr 17

H D, E, G 7 Apr 21 Apr 27

Network Calculations – Calendar

Look at activity A – Duration of 3 with a start of Apr 1 & complete Apr 5????


Non work days

Next activity starts on the first instant of next day

Activity starts on the first instant

of Day 1

Network Calculations–Calendar

Duration Start Complete

Activity A 3 Apr 1 Apr 5

1 2 31 2 3 4 5 6

Thu Fri Sat Sun Mon Tue


Time Phased Bar Chart

Task Name Start Finish

ATP 3/17/03 3/17/03

Task A 3/17/03 3/19/03

Task B 3/20/03 3/26/03

Task C 3/20/03 3/24/03

Task D 3/20/03 3/25/03

Task E 3/27/03 4/1/03

Task F 3/26/03 3/27/03

Task G 4/2/03 4/2/03

Contract Complete 4/2/03 4/2/03

ATP

Contract Complete

F S S M T W T F S S M T W T F S S M T W T F S S M T W T F SMar 9, '03 Mar 16, '03 Mar 23, '03 Mar 30, '03 Apr 6, '03

Task Name Start Finish Duration

ATP 3/17/03 3/17/03 0 days

Task A 3/17/03 3/19/03 3 days

Task B 3/20/03 3/26/03 5 days

Task C 3/20/03 3/24/03 3 days

Task D 3/20/03 3/25/03 4 days

Task E 3/27/03 4/1/03 4 days

Task F 3/26/03 3/27/03 2 days

Task G 4/2/03 4/2/03 1 day

Contract Complete 4/2/03 4/2/03 0 days

ATP

0 days

0 days

2 days

3 days

0 days

3 days

0 days

Contract Complete

F S S M T W T F S S M T W T F S S M T W T F S S M T W T F SMar 9, '03 Mar 16, '03 Mar 23, '03 Mar 30, '03 Apr 6, '03


Critical Path Definitions

Critical Path is the longest path The path that defines minimum project time

– The path with the least amount of float– The path on which any activity expansion/delay

lengthens the duration of the project Total Float

– The amount of time an activity can move with out impacting the end date

Free Float – The amount of time an activity can move with

out impacting another activity


Schedule Baseline

A coordinated and approved schedule/plan.

Used to measure status against.

When integrated with cost the result is the Performance Measurement Baseline (PMB)


Schedule Baseline

Schedule Baseline can change as a result of:– Contract Change Orders– Customer Redirection– Internal Replanning– Formal Reprogramming

Baseline changes require formal authorization


Status UpdatesStatus Updates

Identify completed tasks

Identify and status activities in process(remaining duration)

Identify estimated start dates for tasks which were scheduled to have started prior to report date but have not

Check for activities worked out of sequence

Status updates do not require formal approval


Measured against the approved baseline schedule

STEP 1. HOW MUCH WORK WAS ACCOMPLISHED?

STEP 2. WHEN WILL THE WORK COMPLETE?

(Accomplishment)

Time Now

Time Now

(Forecast Completion Date)

Status Updates


Status Updates

Time now

Actual dates:

– Start date

– Finish date

Accomplishment

Remaining duration (how long it will take to finish)

What do I need to know to ‘status’ the schedule?


Status Updates

Determine a “forecast” start or finish

– For activities started but not finished:• Remaining duration, how much longer will it take to

complete the work

– For activities scheduled to finish but are behind schedule:• Remaining duration• Assess the impact to succeeding activities in the network

– For activities not started:• Impact of preceding activities• Assess the impact to succeeding activities in the network


Requires program coordination between IPTs and Scheduler Forecast dates on the schedule must be consistent with time

phased “Estimate To Complete” (ETC) Status continues against the baseline schedule

A recovery plan does not replace the baseline schedule.

Tasks may be re-sequenced, resources realigned, or effort redirected to reducethe current behind schedule conditions to the maximum extent possible.

Currently behind schedule but the baseline completion date will be met.

Time Now

Baseline completion date will not be met.The ETC phasing should be consistent with the schedule forecast dates

Recovery Plan


Status Updates

Task Name Start Finish

ATP 3/17/03 3/17/03

Task A 3/17/03 3/19/03

Task B 3/21/03 3/31/03

Task C 3/22/03 3/26/03

Task D 3/23/03 3/27/03

Task E 4/1/03 4/4/03

Task F 3/28/03 3/31/03

Task G 4/7/03 4/7/03

Contract Complete 4/2/03 4/2/03

ATP

0 days

-3 days-3 days

0 days0 days

1 day

-3 days-3 days

1 day

-3 days-3 days

Contract Complete

3/9 3/16 3/23 3/30 4/6 4/13 4/20March April


Schedule Traceability



The ability to readily track schedule dates, durations, status and revisions at all levels of schedule detail and between schedules at the same level of detail

– Horizontal Traceability– Vertical Traceability



Horizontal Traceability– A schedule dependency between performing

organization– Hand-offs between organizations, teammates,

subcontractors– Activities are dependent upon a preceding

activity• Predecessors have been identified• Successors have been identified


Horizontal Traceability

DesignStart

SectionRelease

EngRelease

Delivery

FabTooling

ProcurementPlanning

Engineering

Manufacturing

Assembly

ATP

What does it look like?


Vertical Traceability

A relationship between different levels of schedule detail– All milestones that appear on a higher level schedule

must be supported by the lower level schedules

– Higher level schedules typically constrain lower level schedules

– Different levels schedules must be linked by reference

– All levels of schedules must be integrated


Vertical Traceability

2.1.9Mech

System

2.1.4Thrust

Structure

2.1.3Ctr Bod y

Str

2.1.7Propulsion

System

2.1.6Avionics System

2.1.5Engine System

2.1.8Thermal System

IntermediateSchedule

WBSLevel 2

WBSLevel 3

2.1 Common Booster Core

2.1.2Tank Assy

What does it look like?



Hand offs between organizations not properly coordinated or formalized (horizontal)

Level of detail schedules are not consistent

No top down schedule direction

No formalized process for linkage or roll-up



To achieve schedule traceability a formalized scheduling process must be in place for all ‘players’

– Common use of data fields by all participants

– Utilization of same processing cycle

– Disciplined status collection

– Disciplined Baseline change control

Strong interdivisional/functional coordination

Strong management support

Rights Reserved 1 CPM-200: Principles of Schedule Management 15 th Annual International Integrated...

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