project planning & scheduling most latest

7/30/2019 Project Planning & Scheduling Most Latest

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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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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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Standard deviation = 1.76 weeks

15 Weeks

(Expected Completion Time)


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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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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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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

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