AMERICAN SPORTS BUILDERS ASSOCIATION CRITICAL PATH METHOD SCHEDULING FOR SUCCESS

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AMERICAN SPORTS BUILDERS ASSOCIATIONCRITICAL
PATH METHODSCHEDULING FOR SUCCESS

• December 6-8, 2008
• New Orleans, Louisiana
• Presented By Bill Pronevitch

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SCHEDULING- Is It Necessary?

• Effective Project Management involves
  coordinating activities such as
• Planning
• Organizing
• Controlling Time (scheduling)
• Cost
• The Scheduling process forces people to
• Quantify their effort in discrete terms
• Place tasks in proper relationships

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SCHEDULING- Methodologies

• Two of the most common methodologies
• Bar Charts
• Critical Path
• ADM Arrow Diagramming Method
• PDM Precedence Diagramming Method
• Both scheduling methods are widely used for
• Controlling
• Making optimal use of project time

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SCHEDULING- Bar Charts

• Bar Charts (also called Gantt Charts) are
  primarily for controlling Time elements
• Analyze/ specify the basic approach to be used
• Segment the work into a reasonable number of
  activities that can be scheduled
• Estimate the time required to perform each
  activity (i.e.- activity duration)
• Place activities in time-order (logic)
• Adjust the chart until the specified completion
  date, if one exists, is satisfied.

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SCHEDULING- Bar Chart
A B C D E F

• Gantt Chart (Bar Chart) shows
• All Activities and Status on a Single Chart

Activities
0 1 2 3 4 5 6 7 8 9
10 11 12
Time in Weeks
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SCHEDULING- Bar Charts

• Benefits
• Plan, Schedule, and Progress on a single chart
• A simple, understandable way to schedule small
  projects or undertakings
• Disadvantages
• Activity-limited, cant handle complex projects
• Doesnt show logic ties (activity relationships)
• Insufficient detail to enable timely detection of
  schedule slippages on long duration activities

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SCHEDULING Critical Path

• The Critical Path Method (CPM) was designed for
  and is useful on projects where the duration of
  each activity can be with
  reasonable certainty
• - it predicts project overall completion
• - it identifies the (critical) activities that
  control the overall length of the project
• CPM is widely used in process industries
  construction and plant outages/ shutdowns.

estimated
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SCHEDULING Critical Path

• Benefits
• Determines shortest project completion time
• Identifies critical activities that can not
  be slipped or delayed (i.e.- TOTAL FLOAT)
• Shows allowable slippage for non-critical
  activities (i.e.- FREE FLOAT)
• Disadvantages
• Large number of activities required
• Difficult to read, understand, and maintain.

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SCHEDULING CPM/ADM

• ADM (Arrow Diagramming Method)
• Arrow (line) represents an Activity
• Tail (of arrow) shows an Activitys start
• Head (of arrow) shows an Activitys finish
• Node (or event) shown at each end
• The Activity Number consists of Head and Tail
  numbers, commonly referred to as I-J nodes (i.e.-
  I-J Method of CPM)

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SCHEDULING CPM/ADM

• ADM Arrow Diagramming Method

Process Work Order
Requisition Material
Install Pump
1
4
5
2
Assign Crew
(Dummy Activity shows relationship, zero
duration)
3
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SCHEDULING CPM/ADM

• Benefits
• Allows use of Dummy Activities which
• Have a ZERO time duration
• Can be used to show additional relationships
• Disadvantages
• An Activitys Predecessor must be complete
  before the Activity can start!
• Neither the Activitys arrow length or arrow
  direction have any meaning

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SCHEDULING CPM/PDM

• PDM (Precedence Diagramming Method)
• Box/ Node represents an Activity
• Line/ Arrow represents a Precedence with time
  and direction properties
• Precedence consist of two parts
• Relationship a Predecessor or Successor
• Lag the (positive or negative) number of work
  periods by which a specified Activity will be
  delayed (assumed to be 0 if not specified)

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SCHEDULING CPM/PDM

• PDM Precedence Diagramming Method

Process Work Order
Requisition Material
Install Pump
A
C
B
Assign Crew
D
Pump Installation Completed
E
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SCHEDULING CPM/PDM

• Types of Relationships, Lags (aa,n)
• FS, 0 Finish-to-Start, With 0 units of delay
• FF, 7 Finish-to-Finish, with 7 units of delay
• SS, 5 Start-to-Start, with 5 units of delay
• SF, 0 Start-to-Finish, with 0 units of delay

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SCHEDULING PDM/ LOGIC

• Relationships (Logic Ties, Lags

Finish -to- Finish
Finish to- Start
(FF,5)
A
A
B
B
(FS,0)
Start to- Finish
Start to- Start
A
B
B
A
(SS,4)
(SF,0)
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SCHEDULING CPM/PDM

• 6 Major Types of Constraints
• Start On a mandatory date
• Start No Earlier Than can start later
• Start No Later Than can start earlier
• Finish On a mandatory date
• Finish No Earlier Than can finish later
• Finish No Later Than can finish earlier
• NOTE Schedule logic drives earlier and
  later start and finish dates

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SCHEDULING- PDM/ OTHER

• Hammock Activity
• Spans many activities to show an overall
  performance period (i.e.- a summary activity)
• Logic Loop
• One of the most common scheduling errors
• Occurs when a set of activities precede each
  other in a circular fashion, (a group of
  activities can never begin nor end)
• Must be eliminated prior to calculating the
  schedule (i.e.- running a time analysis)

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SCHEDULING- Hammock

• PDM Hammock (Summary) Activity

A
B
C
D
E
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SCHEDULING PMD/LOOP

• LOOP No beginning or end
• (a circular path)

A
B
C
D
LOOP
E
F
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SCHEDULING PDM/ CALCS

• Once a network has been created and the durations
  estimated for each activity, both the Total
  Time to reach project completion and each
  activitys individual start and finish times,
  can be calculated
• Manual computation is easy and logical (but
  tedious time-consuming on large projects)
• Forward Pass calculates early start/finish,
  (ES/EF)
• Backward Pass calculates late start/finish,
  (LS/LF)

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SCHEDULING CALCS

• FORWARD PASS
• Calculates Earliest Start and Earliest Finish
  times, observing the following rules
• Assign an ES time to the first activity
• Other activities start as soon as their
  predecessor relationships have been satisfied
• Equations
• ES EF (Pred.) 1
• EF ES Duration - 1

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SCHEDULING CALCS

• BACKWARD PASS
• Calculates Latest Start and Latest Finish
  times, observing the following rules
• Assign an EF time to the last activity.
• All activities finish as soon as their
  Successor relationships have been satisfied.
• Equations
• LF LS (Succ.) 1
• LS LF Duration 1

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SCHEDULING CALCS

• PDM ACTIVITY NOTATION
• Activity Number unique number to an activity
• Duration number of work periods assigned
• ES EF calculated in Forward Pass
• LS LF calculated in Backward Pass
• ACTIVITY NUMBER
• ES EF
• LS LF
• DURATION

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FORWARD BACKWARD PASS
START
FINISH
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FORWARD BACKWARD PASS
1
5
6
19
6
9
10
13
20
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START
5
9
24
Early Dates ESs EFp 1 EFs ESs Ds - 1
FINISH
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FORWARD BACKWARD PASS
5
1
6
19
12
15
16
19
20
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START
24
11
15
Late Dates LFp LSs -1 LSp LFp D 1
FINISH
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FORWARD BACKWARD PASS
5
1
6
19
12
15
16
19
20
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START
24
24
11
15
Late Dates LFp LSs -1 LSp LFp D 1
FINISH
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What is the Scheduling Process?
Report/ Status
Scheduling
Planning
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IDENTIFY MILESTONES

• Project Start
• Project Phase Start and Finishes
• Equipment and/ or Long Lead Item Delivery
• Project Finish

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DEVELOP ACTIVITY LIST(EXAMPLE HOUSE
CONSTURCTION)

• Select Lot
• Clear and Grub Lot
• Install Utilities
• Construct House
• Select Contractors
• Arrange Financing

• Close Financing
• Landscape
• Purchase Appliance and Lighting Fixtures
• Install Flooring
• Paint

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ASSIGN DURATION TO ACTIVITES(EXAMPLE HOUSE
CONSTRUCTION)

• Select Lot 3 days
• Clear and Grub Lot 10 days
• Install Utilities 3 days
• Construct House 60 days
• Select Contractors 5 days
• Arrange Financing 5 days
• Close Financing 1 day
• Landscape 5 days
• Purchase Appliance/Lighting Fixtures 1 day
• Install Flooring 5 days
• Paint 5 days

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SEQUENCE ACTIVITIES

• ASK THREE QUESTIONS!
• What activity must come before this one?
• What activity must come after this one?
• What activities can I perform at the same time?

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REVIEW AND FINALIZE

• Review Relationships
• Review and Finalize Durations
• Review Resource Usage
• Review and Finalize Project End Date
• Does this achieve the desired date?
• If it does not. What is the plan NOW?!?

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SCHEDULING- CONCLUSION

• Planning and scheduling functions are usually
  performed iteratively in order to provide for
  accomplishing all required tasks within the
  specified time frames
• Both Critical Path Methods (ADM PDM) create
  networks showing activity durations and total
  time for project completion
• Failing to Plan is Planning to Fail, hence
  Plan the Work, Work the Plan