Components of a Critical Path Method (CPM) Scheduling System. This describes the five components of a CPM Scheduling system and how they interact. The slide show will help improve ones understanding of scheduling principles.

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Components of a Scheduling
System
Abhi Basu
June 2004
abhibasu@basutech.com

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Components of a Scheduling Tool
 Calendar
 Network
 Activity
 Relationship
 Algorithm
 Scheduling
 Leveling
 Constraints
 Resources
To understand CPM
Scheduling calculations, you
need to understand the
components of the
scheduling systems
Stripping aside the bells &
whistles, there are 5 main
components that make up
the scheduling system.

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Assembling a Schedule - Calendar
Calendar
The first component is the
calendar

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Assembling a Schedule - Activities
Calendar
Activities
The next component is the network with
the sub-component – activity and ….

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Assembling a Schedule -
Relationships
Calendar
Relationships
……. relationship

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Assembling a Schedule - Network
Calendar
Network
Activities and Relationships
together make up the network

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Assembling a Schedule – Forward
Pass
Calendar
Network
Calculation Algorithm
The algorithm
comprises of a
forward pass
and a
backward pass

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Assembling a Schedule – Forward
Pass
Calendar
Network
Calculation Algorithm

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Assembling a Schedule – Backward
Pass
Calendar
Network
Calculation Algorithm

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Assembling a Schedule – Backward
Pass
Calendar
Network
Calculation Algorithm

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Assembling a Schedule
Calendar
Network
Calculation Algorithm
Float

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Assembling a Schedule
Calendar
Network
Calculation Algorithm

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Assembling a Schedule
Calendar
Network
SNET
Applying a Constraint
Constraints restrict the
movement of activities
on the calendar
There are categories
of constraints such as
date constraints and
float constraints etc.

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Assembling a Schedule
Calendar
Network
SNET
Applying a Constraint
Float
Addl. Float

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Assembling a Schedule
Calendar
Network
5-Day Week Calendar

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Assembling a Schedule
Calendar
Network
5-Day & Weekend Calendars
Multiple
calendars cause
anomalies in float
calculations

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P3 MSPSureTrakP3e
Network Components
Activities
Relationship
Calendars
Constraints
Task Dependent
Resource Dependent
Level of Effort
Start Milestone
Finish Milestone
Task
Independent
Meeting
Start Milestone
Finish Milestone
Hammock
WBS
Fixed Duration
Fixed Unit
Fixed Work
Finish to Start
Start to Start
Finish to Finish
Start to Finish
Finish to Start
Start to Start
Finish to Finish
Start to Finish
Finish to Start
Start to Start
Finish to Finish
Start to Finish
Finish to Start
Start to Start
Finish to Finish
Start to Finish
Activity
Relationships
Resource
Shifts
Duration Type
Fixed Units/Time
Fixed Units & Duration/Time
Fixed Units
Fixed Duration & Units
Task
Project
Resources
Task Dependent
Independent
Meeting
Start Milestone
Finish Milestone
Start Flag
Finish Flag
Hammock
WBS
Early
Late
Start On
Mandatory
Expected Finish
ZFF/ZTF
Start On
Start On or After
Start On or Before
Finish On
Finish On or After
Finish On or Before
Start
Finish
As late as possible
Planning Units
Activity
Resource
Activity
Resource
Day, Week,
Month
Must Start On
Start No Earlier Than
Start No Later Than
Must Finish On
Finish No Earlier Than
Finish No Later Than
As Soon As Possible
As Late as possible
Early
Late
Start On
Mandatory
Expected Finish
ZFF/ZTF
Hour, Day
Hour, Day, Week, Month,
Year
Estimated
Hour, Day
Variations in the Internals of Scheduling Packages

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Variations - Continued
 Scheduling and Resource Leveling
Algorithms
 Updating
 Percent Completion and ETC
Calculations
 Large Impact on Results

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Resource Scheduling
Calendar
Resource Scheduling adds
an order of magnitude
difficulty

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Additional Computational
Complications
 Resource Limits and Prioritization
 Resource dependent task durations
 Incompatible Resource Calendars
 Departure from CPM Scheduling basics
At least 3 dimensions
are added to the
calculations

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System Has Become Opaque
 Transparency
 Repeatable Results
 Solvability
The basis of
calculations are not
easy to decipher
Difficult to do
objective
independent
analysis and
verification
System is used for other
goals such as project
administration which may
conflict with the goals of
CPM scheduling

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Tasks Ahead
 Certify the scheduling algorithms
 Fix variations in scheduling packages
 Improve visibility tools
 Establish Standards for Usage
 Require training and certification for
operators
 Research / Establish Additional Metrics