220R89008
EPA
SYSTEMS DEVELOPMENT CENTER
Seminar Series:
Designing and Implementing
an Information System
Seminar No.2:
' Project Scheduling-
A Project Managers Perspective9
December 14, 1989
EPA Education Center Auditorium
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PROJECT SCHEDULING:
A PROJECT MANAGER'S PERSPECTIVE
presented by
Mr. Connie Teetz
Planning Research Corporation
December 14, 1989
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Seminar Objectives
See where scheduling fits in the planning process
Understand basic scheduling methods
Be familiar with scheduling terminology
Know what to look for in a schedule
Recognize the value of automated scheduling tools
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Schedule
GRAPHIC
WORK PLAN
A sequential plan to accomplish work. It focuses on
the tasks to be done and the timing of each task.
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Setting the Foundation - Planning
Determine the project objectives
Break down the work into meaningful tasks
Build a schedule
Determine resource requirements
Assign responsibility for the work
Set up budgets
Analyze risk
Complete project plans
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The Project Plan - A Systematic Approach
An understanding of the objectives
Elimination or reduction in uncertainties
Improvement in efficiency
A basis to monitor performance
A baseline to manage change
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The Project Manager's Role in Project Planning
Effective organization
Comprehensive planning
Realistic schedules
Solid estimates/budgets
Measurement of progress
Allowance for timely recovery
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A Kev Step - Breaking Down the Work
List the major tasks and deliverables
Do a product oriented outline of the project
Go to a level where work will be managed
Set up a coding scheme
Prepare short descriptions of work content
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Medical Waste Information Project
INFORMATION MANAGEMENT SYSTEM CONCEPT
SYSTEM DESIGN / DEFINITION
SYSTEM DEVELOPMENT / IMPLEMENTATION
SYSTEM TESTING
TRANSPORTATION NOTIFICATION DATA BASE
MANAGEMENT TASKS
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The Functions of a Schedule
Logical sequence of the work
Includes all "events", both internal and external
Facilitates resource planning
Supports the budgeting process
Highlights critical tasks
Provides a "road map" for the project
The schedule validates the project plan
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Network Schedules - A Brief History
Program Evaluation and
Review Technique (PERT)
Arrow Diagramming
Method (ADM)
A statistical method using 3 or
more estimates for data input.
Term is used incorrectly to
refer to current network methods
t
Task
Precedence Diagramming
Method (PDM)
Task
Task
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Types of Schedules in Use Today
Bar Chart (Gantt)
Milestone Chart
H-li 1 h
I L
Network Diagrams
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Network Schedules - Loaic Diaarams
Precedence Diagramming Method.... PDM
- Activity-On-Node
Arrow Diagramming Method.............. ADM
Event-On-Node
_ A
B
-o
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Network Schedules - Terms
Task (Activity)
Event -
Milestone
Imposed date
Constraint
Calendar
Critical path
Float
Early start/finish
Late start/finish
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Network Schedules - Constraints
Constraints define the way tasks relate
to one another - (dependencies)
List the tasks and events of a network, then link
them by drawing constraints
Predecessor
"Go Before"
Successor
"X*WWWĞĞ*ĞW*>W<0ĞĞ*W^-!*W'WW
"Gome After"
Constraint
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Constraint Types
Finish-to-Start FS
- Successor cannot start until predecessor finishes
Start-to-Start SS
- Successor can start as soon as predecessor starts
Finish-to-Finish FF
Successor cannot finish until predecessor finishes
Start-to-Finish SF
- Successor cannot finish until predecessor starts
G
B
7Tj
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Network Schedules Calculating Dates
Forward pass
Start from imposed start date and work forward
through the schedule adding the duration of
each activity along each path
Backward pass Start with imposed end date and work backward
through the schedule subtracting the duration of
each activity along each path
Imposed start
' EARLY
START
"Forward Pass"
(Add Durations)
EARLY
FINISH
TASK
LATE
START
"Backward Pass"
(Subtract Durations)
LATE
FINISH
X . /
Imposed finish
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Network Analysis
Attention focused on the identification of:
Critical Tasks
("Schedule Float / Slack )
- Critical Tasks lie along the critical path ... a delay
in any one of these tasks will impact the
completion date of the project
- Critical Path ... timewise, the longest sequence
of connected tasks through a network. Usually,
the path with zero or negative float
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Network Analysis
Concept
Paper
10|
System
Design
B 120
Data
Collection
a
System
Development
Interim
Review
D 3
System
Installation
System
Testing
Data
Entry
H 60
Report
Generation
J I2°l
= Tasks
[Critical Path |
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Network Schedules - Resource Scheduling
Consider skills and/or specifications and mix/availability
Initial estimates show usage profile and total usage
A resource driven schedule may have different dates
Usage profiles may cause overloads/underloads
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What Do You Need To Get Started?
A list of milestones
A list of tasks
The period of performance
Specific delivery/need dates
A work calendar
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What Affects the Schedule?
Durations
Need dates
Resource availability/limits
Logic
External events
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Information Needed to Build a Schedule
Calendars
Project
Wortt
Task Data
Task Number
Task Name
Description
Duration
Resource
Information
People
Material
Availability
Other
Constraint Data
Imposed Dates,
Lag, Lead, etc.
Task
Constraint Types
(Relationships)
FS Finish-to-Start
SS Start-to-Start
SF Start-to-Finish
FF Finish-to-Finish
PRECEDENCE (PDM) NETWORK
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How to Track Progress
Baseline Schedule
Initial contractual work plan that is maintained
for progress evaluations and trend analyses.
Focus *~ Planned Performance
Current Status J
Current status causes changes in planned start/end
dates. This may cause work-around plans and new
projected completion dates
Focus *- Deviations from Baseline
f Operating Schedule ']
Work plans that reflect work-around plans and new
projected dates
Focus Ğğ- Current Performance
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Baseline Schedule
The approved plan for the accomplishment of project
objectives.
. Necessary in order to measure progress/ performance
Project manager should control any changes to the
baseline schedule
* The baseline schedule does not change when tasks slip
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Operating Schedule
The current, updated project schedule used to manage
ongoing tasks
Used to project revised start & finish dates for
all remaining tasks
Useful management tool estimating the cost to
complete the project
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As a Project Manager - What Questions Should You Ask?
Are all tasks, milestones included?
Are external events that effect the project included?
Is the logic sound?
Are the durations realistic?
Are resource estimates accurate?
Is resource utilization efficient?
Is there any float (slack)?
Is the level of detail appropriate?
Can you understand the schedule?
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Automated Schedulina Tools
They help in the process - You still make the decisions!
They can help outline the work (break it down into tasks)
Most use a Bar Chart (Gantt) format for input
They require duration and logic
They can be very helpful in resource leveling
They work best when you keep the number of activities low
Great for "what if" exercises
Know your requirements before you pick one
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Summarv
Scheduling is a key element in the planning process
As a project manager, you play a very important role
Know what to look for in a good schedule
Use the schedule as a management tool
Automated tools don't replace decisions
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SCHEDULING TERMINOLOGY
Activity - See Task
Arrow Diagramming Method (ADMj
A networking technique in which a task is shown as
an arrow between two nodes representing events.
Constraints are depicted as node-to-node
relationships. Also known as Activity-on-Arrow or
I-J (Interface-Juncture) method.
As Late As Possible (ALAP)
A scheduling technique in which the task schedule
is computed by starting with its due date and
working backward to determine the required start
date. An ALAP task is scheduled immediately before
its first successor. Also known as backwards
scheduling.
As Soon As Possible
A scheduling technique in which the task is
scheduled forward in time from the project start
date to determine the required finish date. An
ASAP task is scheduled immediately after its last
predecessor. Also known as forwards scheduling.
Backward Pass
The procedure to establish when tasks and events
must happen by calculating late start and finish
dates with respect to project requirement dates
such as the completion date.
Barchart
A format for displaying schedule data in which a
task's planned time span is depicted as an open
horizontal bar the ends of which correspond to the
scheduled start and finish dates. The task's
progress toward completion is shown by blackening
the open bar along the time scale. Also known as a
Gantt chart, named for Henry Gantt who first used
the scheduling method in the early 1900's.
Baseline
A set of original or approved schedule dates that
can be compared to actual start and finish dates
to determine project status in relation to plan.
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Calendar
The definition of work periods (hours, days,
weeks, months, years) and non-work periods
(weekends, holidays, vacation time for labor
resources)
Coding
Application of unique identifiers to permit
sorting and selection of data and maintain
traceability of a task within the network data
base or between multiple linked data bases.
Constraint
A quantifiable relationship that ties network
tasks and events together. Constraints both
establish (task A cannot start until task B
finishes) and qualify (task A can finish 2 weeks
after receiving the output of task B)
relationships among tasks. Also known as
Dependency and Link. The following four constraint
types are used to designate these relationships:
o Finish-to-start (FS) - Task A
(predecessor) must finish before Task B
(successor) can start. This is the most
commonly used constraint type.
o Start-to-Finish (SF) - Task A
(predecessor) cannot finish before Task
B (successor) is started. This is the
least commonly used constraint type.
o Finish-to-Finish (FF) - Task B
(successor) cannot finish before Task A
(predecessor) is finished. A time value
is sometimes applied to reflect the
amount of work that Task B needs to
accomplish after it receives the output
of Task A.
o Start-to-Start (SS) - Task B (successor)
cannot start before Task A (predecessor)
is started. A time value is sometimes
applied to reflect the amount of work
Task A must accomplish before Task B can
start.
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Critical
Any task with zero or negative float. Critical
tasks are those in which any delay in the task
will delay the completion of the project.
Critical Path
The longest (with respect to the total time
available) path of sequential tasks with the least
amount of float in the network. The critical path
is that string of tasks and events where a delay
in accomplishing any one of them will jeopardize
on-time completion of the project.
Critical Path Method
An analytical technique used to identify real or
potential time reserve, predict the impact of
critical task performance problems and evaluate
the schedule impact of proposed solutions.
Delay
A time delay in a constraint indicating that tasks
are constrained in the middle rather than the
start or finish of their span time. Delay in a
start-to-start constraint is a portion of the
duration of the predecessor task, while delay in a
finish-to-finish constraint represents part of the
successor's duration. Delay may also be used to
limit the number of scheduled tasks as in the case
where shipping is considered a two-week lag in the
constraint between production and installation
tasks. See also Lag and Lead.
Dependency - See Constraint.
Dummy
A task that can be used to build the network
logic, but which does not represent any real work
and cannot have resources applied against it; a
really stupid person.
Duration
The amount of time required to start, perform and
complete a task. Applying numerical values for
duration to a task logic flow transforms it to a
task network.
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Duration-Driven Scheduling
Scheduling only according to the time period
required for work accomplishment without regard
for resource requirements.
Earlv Finish
The earliest date on which a task can be completed
as determined by network time analysis.
Earlv Start
The earliest date on which a task can be started
as determined by network time analysis.
Effort-Driven Scheduling - See Resource-Driven
Scheduling.
End
A task with no logical successors; the last task
in the network.
Event
An instant of time indicating the start or finish
of a task or a project milestone; see also Imposed
Date.
Float
The time value difference between when tasks can
happen (early start/early finish) and when the
must happen (late start/late finish). Also known
as SJ.ack or time reserve. Float is that amount of
time that tasks can slip without delaying other
tasks in the schedule. See also Free Float and
Total Float.
Forward Pass
The forward computation procedure for establishing
the earliest expected start and finish dates for
tasks (early start/early finish) based on their
durations and constraints.
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Free Float
The amount of time a task may be delayed without
affecting any of its successor tasks.
Gantt Chart - See Bar Chart.
Hammock
A technique for summarizing detailed tasks or
subnetworks where start and finish events
represent the earliest start and latest finish of
a set of tasks.
Histogram
A vertical barchart where resource utilization
rates are displayed vertically across a horizontal
time scale.
Imposed Date
A "due by" or "need by" date established
independently of the network development process.
Project milestones are generally established as
imposed dates.
Lag
The amount of time after a predecessor task
finishes that a successor task can start in a
finish-to-start relationship. See also Delay.
Late Finish
The latest date a task can complete without
affecting any successor tasks or the project
completion date.
Late Start
The latest date a task can start without affecting
any successor tasks or the project start date.
Lead
The amount of time before a predecessor task
finishes that a successor task can start in a
finish-to-start relationship. See also Delay.
Link - See Constraint.
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Logic Diagram
Graphic depiction of the relationships among tasks
that shows the sequence and flow of project work;
generally a logical layout of the project WBS
Loop
A network logic error in which tasks are so
constrained that it is impossible to perform a
time analysis because each task is its own
predecessor and/or successor.
Master Schedule
A schedule depicting the entire project plan,
generally at a summary level. The master schedule
may be displayed in either barchart or network
diagram formats.
Milestone
A key occurrence in the project schedule such as
project start, design reviews, delivery date and
project finish. Generally scheduled as a zero
duration event. See also Event and Imposed Date.
Negative Float
The result of a condition where a task's early
dates are later than its late dates; insufficient
time to complete the task; also known as negative
slack.
Network Diagram
A flow chart of the project plan showing task
durations, constraints and the critical path.
PERT Analysis
A method of computing expected task duration where
the weighted average of optimistic, most likely
and pessimistic duration estimates is determined.
PERT is the acronym for Program Evaluation and
Review Technique developed for the Polaris
submarine program in the 1950's.
Percent Complete
A measure of work accomplishment that compares the
amount of effort completed with the total task
effort to be completed; also known as physical
percent complete.
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Positive Float
The result of a condition where a task's early
dates are earlier than its late dates; more than
adequate time to complete the task; also known as
positive slack.
Precedence Diagramming Method fPDM)
A networking technique where tasks are represented
by nodes (rectangular boxes) and constraints are
shown as lines between the nodes. Also known as
Activity on Node.
Predecessor
A task or event that logically flows into another
activity or event.
Project
A set of tasks that must be performed to reach a
specified objective.
Resource
People and material required to accomplish a task.
Resource Allocation
The process of assigning resources to a task.
Resource Conflict
A condition in which a resource workload exceeds
its availability; also known as resource overload.
Resource-Driven Scheduling
A scheduling method that determines task durations
based on the amount of resources available for
task accomplishment.
Resource Leveling
Delaying tasks in the scheduling process until the
required resource is available; scheduling so as
not to exceed the availability of required
resources.
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Resource Pool
A set of resources that may be shared among
several projects.
Selection
Derivation of only specified schedule data that
meets defined criteria. For example, selection of
only those tasks with an early finish date before
a required delivery date.
Slack - See Float.
Sort
To order in a specified manner. For example, a
sort by early start would list the earliest task
first followed by the next chronological task.
Any task without a constraint into its start.
Successor
A task or event that logically follows another
task or event.
Target Date - See imposed Date
Task
Performance of effort in terms of resources
required over a specified period of time;
generally the smallest unit of work that can be
scheduled; also known as an Activity.
Time Analysis
The process of running a forward and backward pass
through the network to determine early start/early
finish and late start/late finish dates for each
task.
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Total Float
The amount of time a task can be delayed without
affecting the completion date of the project.
Zero Float
The result of a condition where a task's early
dates are equal to its late dates; just enough
time to complete the task; also known as zero
slack.
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