mit pert cpm project manag lect9 8x

8/11/2019 Mit Pert Cpm Project Manag Lect9 8x

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Project Management PhaseProject Management Phase

Fin.&Eval.

RiskEstimating

Planning&SchedulingPlanning&SchedulingPlanning&Scheduling

Organization

OutlineOutline

ObjectiveObjective

Bar ChartBar Chart

Network TechniquesNetwork Techniques

CPMCPM

ObjectiveObjective

What are some of the Different Representations for DeterministicWhat are some of the Different Representations for DeterministicSchedules ?Schedules ?

What are some Issues to Watch for?What are some Issues to Watch for?

OutlineOutline

ObjectiveObjective

Bar ChartBar Chart


CPMCPM

Gantt Chart Characteristics

Bar Chart

Henry L. Gantt

World War I - 1917

Ammunition Ordering and Delivery

Activities Enumerated in the Vertical Axis

Activity Duration Presented on the Horizontal Axis

Easy to Read

Simple Gantt ChartSimple Gantt Chart

TimePhase

Year 1 Year 2 Year 3

1. Concept and feasibility studies

2. Engineering and design

3. Procurement

4. Construction

5. Start-up and implementation

6. Operation or utilization

.

Figure by MIT OCW.

Gantt (Bar) ChartsGantt (Bar) Charts

Very effective communication tool

Very popular for representation of simpler schedules

Can be cumbersome when have >100 activities

Key shortcoming: No dependencies captured

Most effective as reporting format rather than representation


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Hierarchy of Gantt ChartsHierarchy of Gantt Charts

Level one plan

Level two plans

Level three plans

Figure by MIT OCW.

Activity AggregationActivity Aggregation

Source: Shtubet al., 1994

Hammock ActivitiesHammock Activities

A graphical arrangement which includes a summary of aA graphical arrangement which includes a summary of agroup of activities in the project.group of activities in the project.

Duration equal to longest sequence of activitiesDuration equal to longest sequence of activities

Activity AggregationActivity Aggregation

Source: Shtubet al., 1994

MilestonesMilestones

A task with a zero duration that acts as a reference pointA task with a zero duration that acts as a reference pointmarking a major project event. Generally used to mark:marking a major project event. Generally used to mark:beginning & end of project, completion of a major phase, or abeginning & end of project, completion of a major phase, or atask for which the duration is unknown or out of control.task for which the duration is unknown or out of control.

Flag the start or the successful completion of a set of activitiFlag the start or the successful completion of a set of activiti eses

OutlineOutline

ObjectiveObjective

Bar ChartBar Chart


CPMCPM

Network SchedulingNetwork Scheduling

A network is a graphical representation of a project plan,A network is a graphical representation of a project plan,showing the intershowing the inter--relationships of the various activities.relationships of the various activities.

When results of time estimates & computations are added to aWhen results of time estimates & computations are added to anetwork, it may be used as a project schedule.network, it may be used as a project schedule.

Source: Badiru& Pulat, 1995

Activity

AEvent i Event j

Activity on ArrowAOA

Activity on NodeAON

ActivityA

ActivityB

AdvantagesAdvantages

CommunicationsCommunications

InterdependencyInterdependency

Expected Project Completion DateExpected Project Completion Date

Task Starting DatesTask Starting Dates

Critical ActivitiesCritical Activities

Activities with SlackActivities with Slack

ConcurrencyConcurrency

Probability of Project CompletionProbability of Project Completion


NetworkNetwork -- DefinitionsDefinitions


NetworkNetwork -- DefinitionsDefinitions


Predecessor Activity of D

Successor Activity of F


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Definitions (ContDefinitions (Contd)d)


Activity

Time and resource consuming effort with a specific time required toperform the task or a set of tasks required by the project

Dummy

Zero time duration event used to represent logical relationships betweenactivities

Milestone

Important event in the project life cycle

Node

A circular representation of an activity and/or event


ArcArc

A line that connects two nodes and can be a representation of anA line that connects two nodes and can be a representation of an event or an activityevent or an activity

Restriction / PrecedenceRestriction / Precedence

A relationship which establishes a sequence of activities or theA relationship which establishes a sequence of activities or the start or end of anstart or end of anactivityactivity

Predecessor ActivityPredecessor Activity

An activity that immediately precedes the one being consideredAn activity that immediately precedes the one being considered

Successor ActivitySuccessor Activity

An activity that immediately follows the one being consideredAn activity that immediately follows the one being considered

Descendent ActivityDescendent Activity

An activity restricted by the one under considerationAn activity restricted by the one under consideration

Antecedent ActivityAntecedent Activity

An activity that must precede the one being consideredAn activity that must precede the one being considered




Merge PointMerge Point

Exists when two or more activities are predecessors to a singleExists when two or more activities are predecessors to a single activityactivity(the merge point)(the merge point)

Burst PointBurst Point

Exists when two or more activities have a common predecessor (thExists when two or more activities have a common predecessor (theeburst point)burst point)

NetworkNetwork

Graphical portrayal of the relationship between activities andGraphical portrayal of the relationship between activities andmilestones in a projectmilestones in a project

PathPath

A series of connected activities between any two events in a netA series of connected activities between any two events in a networkwork

OutlineOutline

ObjectiveObjective

Bar ChartBar Chart


CPMCPM

Critical Path Method (CPM)Critical Path Method (CPM)

DuPont, Inc., and UNIVAC Division of Remington RandDuPont, Inc., and UNIVAC Division of Remington Rand

Scheduling Maintenance Shutdowns in Chemical ProcessingScheduling Maintenance Shutdowns in Chemical ProcessingPlantsPlants

~1958~1958

Construction ProjectsConstruction Projects

Time and Cost ControlTime and Cost Control

Deterministic TimesDeterministic Times

CPM ObjectiveCPM Objective

Determination of the critical path: the minimum time for a projeDetermination of the critical path: the minimum time for a proje ctct

CPM PrecedenceCPM Precedence


Technical PrecedenceTechnical Precedence

Caused by the technical relationships among activities (e.g., inCaused by the technical relationships among activities (e.g., in conventionalconventionalconstruction, walls must be erected before roof installation)construction, walls must be erected before roof installation)

Procedural PrecedenceProcedural Precedence

Determined by organizational policies and procedures that are ofDetermined by organizational policies and procedures that are oftentensubjective with no concrete justificationsubjective with no concrete justification

Imposed PrecedenceImposed Precedence

E.g., Resource Imposed (Resource shortage may require one task tE.g., Resource Imposed (Resource shortage may require one task to be beforeo be beforeanother)another)

CPM: AOA & AONCPM: AOA & AON

Activity-on-Arrow

Activity-on-Node

Source: Feigenbaum, 2002Newitt, 2005


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CPM CalculationsCPM Calculations

Source: Hegazy, 2002Hendrickson and Au, 1989/2003

Forward PassForward Pass

Early Start Times (ES)Early Start Times (ES)

Earliest time an activity can start without violating precedenceEarliest time an activity can start without violating precedence relationsrelations

Early Finish Times (EF)Early Finish Times (EF)

Earliest time an activity can finish without violating precedencEarliest time an activity can finish without violating precedence relationse relations

Forward PassForward Pass -- IntuitionIntuition

ItIts 8am. Suppose you want to know the earliest time you cans 8am. Suppose you want to know the earliest time you canarrange to meet a friend after performing some tasksarrange to meet a friend after performing some tasks

Wash hair (5 min)Wash hair (5 min)

Boil water for tea (10 min)Boil water for tea (10 min)

Eat breakfast (10 min)Eat breakfast (10 min)

Walk to campus (5 min)Walk to campus (5 min)

What is the earliest time you could meet your friend?What is the earliest time you could meet your friend?

CPM CalculationsCPM Calculations

Source: Hegazy, 2002Hendrickson and Au, 1989/2003

Backward PassBackward Pass

Late Start Times (LS)Late Start Times (LS)

Latest time an activity can start without delaying the completioLatest time an activity can start without delaying the completion of the projectn of the project

Late Finish Times (LF)Late Finish Times (LF)

Latest time an activity can finish without delaying the completiLatest time an activity can finish without delaying the completion of theon of theprojectproject

Backward PassBackward Pass -- IntuitionIntuition

Your friend will arrive at 9am. You want to know by what timeYour friend will arrive at 9am. You want to know by what timeyou need to start all thingsyou need to start all things





What is the latest time you should start?What is the latest time you should start?

Slack or FloatSlack or Float

ItIts 8am, and you know that your friend will arrive at 9am. Hows 8am, and you know that your friend will arrive at 9am. Howmuch do you have as free time?much do you have as free time?





CPM ExampleCPM Example




ES(kES(k) =) = Max{EF(iMax{EF(i)}, i)}, i P(kP(k))

EF(kEF(k) =) = ES(kES(k) +) + D(kD(k))



ES(kES(k) =) = Max{EF(iMax{EF(i)}, i)}, i P(kP(k))

EF(kEF(k) =) = ES(kES(k) +) + D(kD(k))


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LF(kLF(k) =) = Min{LS(jMin{LS(j)} j)} j S(kS(k))

LS(kLS(k) =) = LF(kLF(k))D(kD(k))



LF(kLF(k) =) = Min{LS(jMin{LS(j)} j)} j S(kS(k))

LS(kLS(k) =) = LF(kLF(k))D(kD(k))

Slack or FloatSlack or Float

The amount of flexibility an activity possessesThe amount of flexibility an activity possesses

Degree of freedom in timing for performing taskDegree of freedom in timing for performing task

Source: Hendrickson and Au, 1989/2003

Total Slack or FloatTotal Slack or Float

Total Slack or Float (TS or TF)Total Slack or Float (TS or TF)

Max time can delay w/o delaying the projectMax time can delay w/o delaying the project

TS(kTS(k) = {) = {LF(kLF(k)) -- EF(kEF(k)} or {)} or {LS(kLS(k)) -- ES(kES(k)})}

Free Slack or FloatFree Slack or Float Free Slack or Float (FS or FF)Free Slack or Float (FS or FF)

Max time can delay w/o delaying successorsMax time can delay w/o delaying successors

FS(kFS(k) =) = Min{ES(jMin{ES(j)})} -- EF(kEF(k) j) j S(kS(k))

Independent Slack or FloatIndependent Slack or Float Independent Slack or Float (IF)Independent Slack or Float (IF)

Like Free float but assuming worstLike Free float but assuming worst--case finish of predecessorscase finish of predecessors

IF(kIF(k) = Max { 0, () = Max { 0, ( Min(ES(jMin(ES(j)))) -- Max(LF(iMax(LF(i))))D(kD(k) ) } j) ) } j S(kS(k), i), i P(kP(k))

CPM AnalysisCPM Analysis

Adapted from: Badiru& Pulat, 1995

Critical PathCritical Path

The path with the least slack or float in the networkThe path with the least slack or float in the network

Activities in that path: critical activitiesActivities in that path: critical activities

For algorithm as described, at least one such pathFor algorithm as described, at least one such path

Must be completed on time or entire project delayedMust be completed on time or entire project delayed

Determines minimum time required for projectDetermines minimum time required for project

Consider nearConsider near--critical activities as well!critical activities as well!


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Critical PathCritical Path


Path CriticalityPath Criticality

= minimum total float

= maximum total float

= total float or slack in current path

Rank paths from more critical to less criticalRank paths from more critical to less critical

max

min

%1000


Calculate Path CriticalityCalculate Path Criticality

minmin = 0,= 0, maxmax = 5= 5

Path 1: [(5Path 1: [(5--0)/(50)/(5--0)](100 %) = 100 %0)](100 %) = 100 %

Path 2: [(5Path 2: [(5--3)/(53)/(5--0)](100 %) = 40 %0)](100 %) = 40 %

Path 3: [(5Path 3: [(5--4)/(54)/(5--0)](100 %) = 20 %0)](100 %) = 20 %

Path 4: [(5Path 4: [(5--5)/(55)/(5--0)](100 %) = 0 %0)](100 %) = 0 %

Path CriticalityPath Criticality -- ExampleExample

mit pert cpm project manag lect9 8x

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