project planning & scheduling most latest
TRANSCRIPT
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Project Planning & Scheduling
Yousaf Ali KhanDepartment of Management Sciences and Humanities
GIK Institute of Engineering Sciences and Technology
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What is a Project? An individual or collaborative enterprise that is
carefully planned and designed to achieve aparticular aim
EXAMPLES: constructing a new road
building a ship designing and marketing a new product moving to a new office block installation of a computer system.
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Objectives and Tradeoffs
Meet the
specifications
Meet the
Deadline--schedule
Due Date!
Stay within
the budget
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Management of Projects
Planning- goal setting, defining the project, teamorganization
Scheduling- relates people, money, and supplies tospecific activities and activities to each other
Controlling- monitors resources, costs, quality, and
budgets; revises plans and shifts resources to meettime and cost demands
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Planning
Objectives
Resources
Work break-downschedule
Organization
Scheduling
Project activities
Start & end times
Network
Controlling
Monitor, compare, revise, action
Project Management Activities
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Establishing objectives
Defining project
Creating work breakdown
structure Determining
resources
Forming organization
Project Planning
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Often temporary structure
Uses specialists from entire company
Headed by project manager Coordinates activities
Monitors scheduleand costs
Permanentstructure calledmatrix organization
Project Organization
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A Sample ProjectOrganization
TestEngineer
MechanicalEngineer
Project 1 ProjectManager
Technician
Technician
Project 2 ProjectManager
ElectricalEngineer
ComputerEngineer
Marketing FinanceHuman
Resources
DesignQuality
Mgt
Production
President
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The Role of
the Project Manager
Highly visibleResponsible for making sure that:
All necessary activities are finished in order and ontime
The project comes in within budget
The project meets quality goals The people assigned to the project receive
motivation, direction, and information
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Project Life Cycle
Concept
Feasibility
Planning
Execution
Closure
Manag
ement
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Work Breakdown Structure
(WBS)Level
1. Project
2. Major tasks in the project
3. Subtasks in the major tasks
4. Activities (or work packages)to be completed
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Example Of WBS For Building aHouse
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Identifying precedence relationships
Sequencing activities
Determining activity times & costs Estimating material and worker
requirements
Determining critical activities
Project Scheduling
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1. Shows the relationship of each activity toothers and to the whole project
2. Identifies the precedence relationshipsamong activities
3. Encourages the setting of realistic time
and cost estimates for each activity4. Helps make better use of people, money,
and material resources by identifyingcritical bottlenecks in the project
Purposes of Project Scheduling
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Gantt chart
Critical Path Method
(CPM) Program Evaluation
and Review Technique(PERT)
Project Scheduling Techniques
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Gantt Charts Shown as a bar charts
Do not show precedence relations Visual & easy to understand
Network Methods
Shown as a graphs or networks Show precedence relations
More complex, difficult to understand and costlythan Gantt charts
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PERT and CPM
Network techniques
Developed in 1950s
CPM by DuPont for chemical plants (1957)
PERT by Booz, Allen & Hamilton with theU.S. Navy, for Polaris missile (1958)
Consider precedence relationships and
interdependencies Each uses a different estimate of
activity times
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Six Steps PERT & CPM
1. Define the project and prepare the workbreakdown structure
2. Develop relationships among the activities -decide which activities must precede and which
must follow others3. Draw the network connecting all of the activities
4. Assign time and/or cost estimates to each activity
5. Compute the longest time path through the network
this is called the critical path6. Use the network to help plan, schedule, monitor,
and control the project
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Questions PERT & CPMCan Answer
1. When will the entire project be completed?
2. What are the critical activities or tasks in the project?
3. Which are the noncritical activities?
4. What is the probability the project will be completed by a
specific date?5. Is the project on schedule, behind schedule, or ahead of
schedule?
6. Is the money spent equal to, less than, or greater than thebudget?
7. Are there enough resources available to finish the projecton time?
8. If the project must be finished in a shorter time, what isthe way to accomplish this at least cost?
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Constant-Time Networks
Activity times are assumed to be constant
Activities are represented by Arcs in the network
Nodes show the events
Notations used in calculating start and finish times:
ES(a) =Early Start of activity a
EF(a) = Early Finish of activity a
LS(a) = Late Start of activity a
LF(a) = Late Finish of activity a
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A Comparison of AON andAOA Network Conventions
Activity on Activity Activity onNode (AON) Meaning Arrow (AOA)
A comes before B,which comes
before C
(a) A B C
BA C
A and B must bothbe completed beforeC can start
(b)
A
C
CB
A
B
B and C cannotbegin until A iscompleted
(c)
B
A
CA
B
C
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Rules
1. One node has no arc entering and defines thestartingevent.
2. One node has no arc leaving and defines thefinishingevent.
3. Each activity should appear exactly once as an arc of
the network, and lies on a path from the starting eventto the finishing event. Dummy activities can also beused.
4. There should be a path passing successively throughany two activities if and only if the first is a pre-
requisite for the second.5. There should be at most one arc between each pair of
nodes of a network.
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Drawing Project Networks
We consider an activity-on-arc approach.We need a list ofactivities (constituent elements of a
project) and their prerequisites.
Example. Planting a treeDescription Activity Prerequisites
Dig hole A -
Position tree B AFill in hole C B
A B C1 2 3 4
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Analysing Project Networks
Number the nodes so that each arc is directedfrom a node i to a node j where i < j.
Let A be the set of activities
dijbe the duration of activity (i, j)
n be the number of nodes.
Compute earliest event times, assuming that theproject starts at time zero and all activities are
scheduled as early as possible.
EET1 = 0
EETj= max{EETi+ dij} j=2,,n(i,j)A
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Analysing Project NetworksNote that EETj is the length of a longest path from
node 1 to nodej.The project duration is EETn.
Compute latest event times, assuming that the
project finishes at time EETnand all activities arescheduled as late as possible.
LETn = EETn
LETi= min{LETj- dij} i=n-1,,1(i,j)A
Note that LETn-LETi is the length of a longest path
from node ito node n.
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Determining the Project Schedule
Perform a Critical Path Analysis The critical path is the longest path through the
network
The critical path is the shortest time in which the
project can be completed
Any delay in critical path activities delays the project
Critical path activities have no slack time
Slack is the length of time an activity can be delayed
without delaying the entire project
Slack = LS ES or Slack = LF EF
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Example
Activity Description Immediate
Predecessors
A Lease the site
B Hire the workers
C Arrange for the Furnishings A
D Install the furnishings A, B
E Arrange for the phones C
F Install the phones C
G Move into the Office D, E
H Inspect and test F, G
Precedence and times for Opening a New Office
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Determining the Project Schedule
Perform a Critical Path AnalysisActivity Description Time (weeks)
A Lease the site 2
B Hire the workers 3
C Arrange for the furnishings 2 D Install the furnishings 4
E Arrange for the phones 4
F Install the phones 3
G Move into the office 5
H Inspect and test 2
Total Time (weeks) 25
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AOA Network For
Opening a New Office
H
(Inspect/Test)
7DummyActivity
6
5D
(Install thefurnishings)
4C
(Arrange forthe
furnishings)
1
3
2
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Determining the Project
SchedulePerform a Critical Path Analysis
A
Activity Name orSymbol
EarliestStart
ES
EarliestFinishEF
LatestStart
LS LatestFinish
LF
Activity Duration
2
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ES/EF Network for Openinga New Office
Start
0
0
ES
0
EF = ES + Activity time
A
2
EF of A =ES of A + 2
2
ESof A
0
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ES/EF Network for Openinga New Office
E
4
F
3
G
5
H
2
4 8 13 15
4
8 13
7
D
4
3 7
C
2
2 4
B
3
0 3
Start
0
0
0
A
2
20
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LS/LF Network for Openinga New Office
E
4
F
3
G
5
H
2
4 8 13 15
4
8 13
7
D
4
3 7
C
2
2 4
B
3
0 3
Start
0
0
0
A
2
20
LF = EFof Project
1513
LS = LF Activity time
LF = Min(LS of followingactivity)
10 13
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Computing Slack Time
After computing the ES, EF, LS, and LF timesfor all activities, compute the slack or freetime for each activity
Slack is the length of time an activity can be delayedwithout delaying the entire project
Slack = LS ES or Slack = LF EF
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Computing Slack Time
Earliest Earliest Latest Latest OnStart Finish Start Finish Slack Critical
Activity ES EF LS LF LS ES Path
A 0 2 0 2 0 Yes
B 0 3 1 4 1 No
C 2 4 2 4 0 Yes
D 3 7 4 8 1 No
E 4 8 4 8 0 Yes
F 4 7 10 13 6 No
G 8 13 8 13 0 Yes
H 13 15 13 15 0 Yes
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Critical Path for Opening aNew Office
E
4
F
3
G
5
H
2
4 8 13 15
4
8 13
7
13 15
10 13
8 13
4 8
D
4
3 7
C
2
2 4
B
3
0 3
Start
0
0
0
A
2
20
42
84
20
41
00
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ES EF Gantt Chartfor Opening a New Office
A Lease the site
B Hire the workers
C Arrange for thefurnishings
D Install the furnishings
E Arrange for the phones
F Install the phones
G Move into the office
H Inspect and test
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
A
B
C
D
E
F
G
H
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CPM assumes we know a fixed time estimate foreach activity and there is no variability in activitytimes
PERT uses a probability distribution for activity
times to allow for variability
Variability in Activity Times
Three time estimates are required
Optimistic time (a) if everything goesaccording to plan
Mostlikely time (m) most realistic estimate
Pessimistic time (b) assuming veryunfavorable conditions
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Probabilistic Time Estimates
Optimistic time
Time required under optimal conditions
Pessimistic time Time required under worst conditions
Most likely time
Most probable length of time that will be
required
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Probabilistic Estimates
Activity
start
Optimistic
time
Most likely
time (mode)
Pessimistic
time
to tptm te
Beta Distribution
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Expected Time
te =to + 4tm +tp
6
te = expected time
to = optimistic time
tm
= most likely time
tp = pessimistic time
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Variance
2 =(tp to)
2
36
2 = variance
to = optimistic time
tp = pessimistic time
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1-2-3
(H)7Dummy
Activity6
52-4-6
(D)
41-2-3
(C)
1
3
2
Optimistic
timeMost likely
time
Pessimistic
time
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Computing Variance
Most ExpectedOptimistic Likely Pessimistic Time Variance
Activity a m b t = (a + 4m + b)/6 [(b a)/6]2
A 1 2 3 2 .11
B 2 3 4 3 .11C 1 2 3 2 .11D 2 4 6 4 .44E 1 4 7 4 1.00F 1 2 9 3 1.78G 3 4 11 5 1.78
H 1 2 3 2 .11
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Probability of ProjectCompletion
Project variance is computed bysumming the variances of criticalactivities
s2 = Project variance
= (variances of activities
on critical path)
p
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Probability of ProjectCompletion
Project variance is computed by summingthe variances of critical activities
Project variance
2 = .11 + .11 + 1.00 + 1.78 + .11 = 3.11
Project standard deviationp = Project variance
= 3.11 = 1.76 weeks
p
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Probability of ProjectCompletion
Standard deviation = 1.76 weeks
15 Weeks
(Expected Completion Time)
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Probability of ProjectCompletion
What is the probability this project can becompleted on or before the 16 weekdeadline?
Z = /p
= (16 wks 15 wks)/1.76
= 0.57
due expected datedate of completion
Where Z is the number of standard deviationsthe due date or target date lies from the
mean or expected date
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Probability of ProjectCompletion
What is the probability this project can becompleted on or before the 16 weekdeadline?
Z= /sp
= (16 wks 15 wks)/1.76
= 0.57
due expected datedate of completion
Where Z is the number of standarddeviations the due date or target date lies
from the mean or expected date
.00 .01 .07 .08
.1 .50000 .50399 .52790 .53188
.2 .53983 .54380 .56749 .57142
.5 .69146 .69497 .71566 .71904
.6 .72575 .72907 .74857 .75175
From Appendix I
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Probability of ProjectCompletion
Time
Probability
(T 16 weeks)
is 71.57%
0.57 Standard deviations
15 16
Weeks Weeks
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What Project Management Has
Provided So Far The projects expected completion time
is15 weeks
There is a71.57% chance the equipmentwill be in place by the16 week deadline
Five activities(A, C, E, G, and H) are onthe critical path
Three activities(B, D, F) are not on thecritical path and have slack time
A detailed schedule is available
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Advantages of PERT/CPM
1. Especially useful when scheduling and controlling largeprojects
2. Straightforward concept and not mathematically complex
3. Graphical networks help highlight relationships amongproject activities
4. Critical path and slack time analyses help pinpointactivities that need to be closely watched
5. Project documentation and graphics point out who isresponsible for various activities
6. Applicable to a wide variety of projects
7. Useful in monitoring not only schedules but costs as well
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Trade-Offs And Project Crashing
The project is behind schedule
The completion time has beenmoved forward
It is not uncommon to face thefollowing situations:
Shortening the duration of the projectis called project crashing
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Factors to Consider When
Crashing A Project The amount by which an activity is crashed
is, in fact, permissible
Taken together, the shortened activitydurations will enable us to finish theproject by the due date
The total cost of crashing is as small aspossible
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Steps in Project Crashing
1. Compute the crash cost per time period. Ifcrash costs are linear over time:
Crash costper period =
(Crash costNormal cost)(Normal timeCrash time)
2. Using current activity times, find the criticalpath and identify the critical activities
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Steps in Project Crashing
3. If there is only one critical path, then select theactivity on this critical path that (a) can still becrashed, and (b) has the smallest crash cost perperiod. If there is more than one critical path, then
select one activity from each critical path such that(a) each selected activity can still be crashed, and (b)the total crash cost of all selected activities is thesmallest. Note that the same activity may be commonto more than one critical path.
4. Update all activity times. If the desired due date hasbeen reached, stop. If not, return to Step 2.
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Crashing The Project
Time (Wks) Cost ($) Crash Cost CriticalActivity Normal Crash Normal Crash Per Wk ($) Path?
A 2 1 22,000 22,750 750 Yes
B 3 1 30,000 34,000 2,000 No
C 2 1 26,000 27,000 1,000 YesD 4 2 48,000 49,000 1,000 No
E 4 2 56,000 58,000 1,000 Yes
F 3 2 30,000 30,500 500 No
G 5 2 80,000 84,500 1,500 Yes
H 2 1 16,000 19,000 3,000 Yes
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Crash and Normal Times andCosts for Activity B
| | |
1 2 3 Time (Weeks)
$34,000
$33,000
$32,000
$31,000
$30,000
ActivityCost
Crash
Normal
CrashCost
NormalCost
Crash Cost/Wk =Crash CostNormal Cost
Normal TimeCrash Time
=$34,000$30,000
31
= = $2,000/Wk$4,000
2 Wks
Figure 3 16