44578964-pert-cpm (1)
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A A A A
PERTPERT -- CPMCPM
PERTPERT-- PROGRAM EVALUATION AND REVIEW TECHNIQUEPROGRAM EVALUATION AND REVIEW TECHNIQUE
CPMCPM-- CRITICAL PATH METHODCRITICAL PATH METHOD
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PURPOSES of PERT CPMPURPOSES of PERT CPMTHE MANAGEMENT WILL BE ABLE TO:THE MANAGEMENT WILL BE ABLE TO:
1.1. TO OBTAIN A GRAPHICAL DISPLAY OFTO OBTAIN A GRAPHICAL DISPLAY OF
THE ACTIVITIES OF THE PROJECT ANDTHE ACTIVITIES OF THE PROJECT AND
THUS, BE ABLE TO VISUALIZE ITSTHUS, BE ABLE TO VISUALIZE ITS
ENTIRETY.ENTIRETY.2.2. DETERMINE THE TIME WHEN ADETERMINE THE TIME WHEN A
PARTICULAR PART OF ACTIVITY OF THEPARTICULAR PART OF ACTIVITY OF THE
PROJECT WILL START AND FINISH.PROJECT WILL START AND FINISH.
3.3. DETERMINE THE CRITICAL PATHSDETERMINE THE CRITICAL PATHS
(THOSE THAT MUST NOT BE DELAYED)(THOSE THAT MUST NOT BE DELAYED)
OF THE PROJECT.OF THE PROJECT.
4.4. MONITOR AND CONTROL PROJECTMONITOR AND CONTROL PROJECT
EFFICIENTLY.EFFICIENTLY.
5.5. USE RESOURCES PROPERLY.USE RESOURCES PROPERLY.
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THREE (3) BASIC PHASES OF PMTHREE (3) BASIC PHASES OF PM
BY PERTBY PERT--CPMCPM
1.1. PLANNINGPLANNING
2.2. SCHEDULINGSCHEDULING
3.3. CONTROLLINGCONTROLLING
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TERMINOLOGYTERMINOLOGY
NETWORKNETWORK-- a project in graphicala project in graphicalform. It consist primarily of events andform. It consist primarily of events andactivitiesactivities
ACTIVITIESACTIVITIES-- occur time and presentoccur time and presentthings that must happen to complete athings that must happen to complete aproject.project.
EVENTSEVENTS-- are points in timeare points in timerepresenting the start or completion of representing the start or completion of particular activities.particular activities.
NODENODE-- represents the sequence of represents the sequence of events as they occur and each isevents as they occur and each isnumbered in logical order numbered in logical order
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TERMINOLOGYTERMINOLOGY
DUMMY ACTIVITIESDUMMY ACTIVITIES-- are dottedare dottedarrows that indicate logicalarrows that indicate logicalrelationship between different events.relationship between different events.
TIME ESTIMATE (TE)TIME ESTIMATE (TE)-- is the estimatedis the estimated
duration required to accomplish anduration required to accomplish anindividual activity.individual activity.
EARLY START TIME (EST)EARLY START TIME (EST)-- is theis theearliest allowable point in time thatearliest allowable point in time thatany event may occur.any event may occur.
LATE START TIME (LST)LATE START TIME (LST)-- is the latestis the latestallowable point in time that any eventallowable point in time that any eventmay start without delaying the project.may start without delaying the project.
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TERMINOLOGYTERMINOLOGY
EARLY FINISH TIME (EFT)EARLY FINISH TIME (EFT)-- is the earliestis the earliestallowable point in time that any event mayallowable point in time that any event maystart without delaying the project.start without delaying the project.
LATE FINISH TIME (LFT)LATE FINISH TIME (LFT)-- is the latestis the latestallowable point in time that any event mayallowable point in time that any event mayfinish without delaying the project.finish without delaying the project.
FLOATFLOAT-- amount of spare time available toamount of spare time available tocomplete an event or activity.complete an event or activity.
MERGE POINTMERGE POINT-- is where more than oneis where more than oneactivity ends in an event.activity ends in an event.
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DIFFERENCE BETWEEN PERT and CPMDIFFERENCE BETWEEN PERT and CPM
PERTPERT CPMCPM
NETWORK DIAGRAMSNETWORK DIAGRAMS
PERT was ³Event oriented´,PERT was ³Event oriented´,i.e., it viewed the project ini.e., it viewed the project in
terms of milestones whichterms of milestones which
had to take place.had to take place.
PERT was geared for PERT was geared for management reportingmanagement reporting
CPM was ³Activity oriented´,CPM was ³Activity oriented´,i.e., it broke the project downi.e., it broke the project down
into activities which need tointo activities which need to
be managedbe managed
CPM having was designed toCPM having was designed to
plan, schedule, and controlplan, schedule, and control
workwork
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DIFFERENCE BETWEEN PERT and CPMDIFFERENCE BETWEEN PERT and CPM
PERTPERT CPMCPM
SCHEDULINGSCHEDULING
PERT, dealing with researchPERT, dealing with researchand development useand development use
statistical methods, used asstatistical methods, used as
an expected time estimatean expected time estimate
based on three timebased on three time
estimates, deriving a formulaestimates, deriving a formula
based on Beta distribution.based on Beta distribution.
CPM having been designedCPM having been designedfor construction work, usedfor construction work, used
only one estimate becauseonly one estimate because
there was enough historicalthere was enough historical
data to generate fairlydata to generate fairly
certain duration estimate.certain duration estimate.
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DIFFERENCE BETWEEN PERT and CPMDIFFERENCE BETWEEN PERT and CPM
PERTPERT CPMCPM
RESOURCE ANALYSISRESOURCE ANALYSIS
PERT did not extendPERT did not extendbeyond time since it dealt inbeyond time since it dealt in
terms of milestone whichterms of milestone which
do not consume resourcesdo not consume resources
CPM included a practicalCPM included a practicalmethod for analyzing themethod for analyzing the
effect on the cost varyingeffect on the cost varying
project times, including theproject times, including the
ability to handle manpower ability to handle manpower
and equipment resourcesand equipment resources
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DIFFERENCE BETWEEN PERT and CPMDIFFERENCE BETWEEN PERT and CPM
HYBRID PERTHYBRID PERT -- CPMCPM
As both systems gained widespread use, modificationsAs both systems gained widespread use, modifications
were introduced to both systems.were introduced to both systems.
In 1961, PERT were adopted the PERT/COST systemIn 1961, PERT were adopted the PERT/COST system
using single time estimate.using single time estimate.
CPM, on the other hand, had borrowed from PERTCPM, on the other hand, had borrowed from PERT
such features as exceptional reporting andsuch features as exceptional reporting and
computerized updating.computerized updating.
What evolved was the Hybrid Technique now referredWhat evolved was the Hybrid Technique now referred
as the PERTas the PERT--CPM.CPM.
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DETERMINATION ANDDETERMINATION AND
CALCULATIONS OF CRITICALCALCULATIONS OF CRITICAL
PATHPATHTo achieve the success of the project,To achieve the success of the project,
analysis of the network is important. Theanalysis of the network is important. The
interaction of different activities in theinteraction of different activities in the
network leads to the determination of thenetwork leads to the determination of the
start and completion time which needstart and completion time which need
computation. The calculations of thecomputation. The calculations of the
completion times are performed directly oncompletion times are performed directly on
the arrow diagram using simple arithmeticthe arrow diagram using simple arithmetic
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TWO METHODS of FINDING theTWO METHODS of FINDING the
CRITICAL PATHCRITICAL PATH
1. a)1. a) BY COMPLETE ENUMERATIONBY COMPLETE ENUMERATION
STEPS:STEPS:
1.1. List all paths leading from the beginningList all paths leading from the beginning
of the project to its end.of the project to its end.2.2. The path with the largest duration is theThe path with the largest duration is the
critical path.critical path.Solution:Solution:
PathPath Total DurationTotal Duration11--22--33--44--55--66--77 7+8+5+7+3=7+8+5+7+3=3030 largest durationlargest duration
11--22--33--66--77 7+8+12+3=227+8+12+3=22
11--22--55--66--77 7+6+4+3=207+6+4+3=20
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TWO METHODS of FINDING theTWO METHODS of FINDING the
CRITICAL PATHCRITICAL PATH
A.A. TIME BOUNDARY METHODTIME BOUNDARY METHOD
STEPS:STEPS:
1.1. Compute the earliest start/finish time of Compute the earliest start/finish time of the project to its end.the project to its end.
2.2. Compute the slack time and determineCompute the slack time and determine
the critical and nonthe critical and non--critical activities.critical activities.
Critical activities have zero slack time.Critical activities have zero slack time.
3.3. Determine the critical pathDetermine the critical path ± ± pathpath
connecting all activities.connecting all activities.
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S AMPLE PROBLEMS AMPLE PROBLEM
1
3
2
5
4
6 7 A
B
C
D
E
F
G
H7
8
5
12
6
4
3
7
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TIME BOUDARY PASSTIME BOUDARY PASS
F orward PassF orward PassPathPath DurationDuration ES ES E F E F
11--22
22--33
22--5533--44
33--66
44--66
55--66
66--77
77
88
6655
1212
77
44
33
00
77
777+8= 157+8= 15
7+8= 157+8= 15
7+8+5= 207+8+5= 20
7+6= 137+6= 13
7+8+5+7= 277+8+5+7= 27
7+8+12=7+8+12=
27max27max
7+6+4= 177+6+4= 17
7
15
1320
27
27
17
30
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TIME BOUDARY PASSTIME BOUDARY PASS
Backward PassBackward Pass
PathPath DurationDuration ES ES E F E F
66--77
55--66
44--66
33--66
33--44
22--5522--33
11--22
33
44
77
1212
55
6688
77
3030
2727
2727
2727
2020
23231515
77
2727
2323
2020
1515
1515
171777
00
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2.2. SOLVING for the SLACK TIMESOLVING for the SLACK TIME
( st= LS ( st= LS ± ± ES)ES)
PathPath DurationDuration LS LS ES ES LS LS - - ES ES
1-2
2-3
2-5
3-4
3-6
4-6
5-6
6-7
7
8
6
5
12
7
4
3
0
7
17
15
15
20
23
27
0
7
7
15
15
20
13
27
0
0
10
0
0
0
10
0
3.3. The critical path is 1The critical path is 1--22--33--44--66--7 and7 and
the critical activities are Athe critical activities are A--BB--DD--GG--HH
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THE COMPUTED CRITICALTHE COMPUTED CRITICAL
PATH NETWORKPATH NETWORK
1
3
2
5
4
6 7 A
B
C
D
E
F
G
H7
8
5
12
6
4
3
7
IT IS NEVER MEANT TO LOOK SIMPLE
SIMPLY BECAUSE WORK IS NEVER SIMPLE.
AT LEAST THIS ALLOWS US TO µSEE¶ THE
WORK GRAPHICALLY.
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