ENGINEERING MANAGEMENT

Project Management Project Management ToolsTools

Older simpler - Gantt ChartOlder simpler - Gantt Chart More modern – CPM/PERTMore modern – CPM/PERT Newest – Microsoft Project Newest – Microsoft Project

™™

Scheduling – planning & controlling Scheduling – planning & controlling benefitsbenefits

It is consistent framework of planning, It is consistent framework of planning, scheduling, monitoring & controlling project. scheduling, monitoring & controlling project.

It illustrates the interdependence of all It illustrates the interdependence of all tasks, work packages, and work elements.tasks, work packages, and work elements.

It denotes the time when specific individual It denotes the time when specific individual must be available for work on a given task.must be available for work on a given task.

It aids in ensuring that the proper comm. It aids in ensuring that the proper comm. take place between department and take place between department and functions.functions.

It determines an expected completion date. It determines an expected completion date. It defines so-called critical activities that, if It defines so-called critical activities that, if

delayed, will delay the project completion.delayed, will delay the project completion.

Contd.Contd. I also identifies activities with slack that I also identifies activities with slack that

can be delayed for some time.can be delayed for some time. It determines the dates at which a task It determines the dates at which a task

should be started.should be started. It illustrates which task must be It illustrates which task must be

coordinated to avoid resources and timing coordinated to avoid resources and timing conflict.conflict.

It also illustrates which task must run It also illustrates which task must run parallel to meet completion date.parallel to meet completion date.

It relieves interpersonal conflict by It relieves interpersonal conflict by showing task dependencies. showing task dependencies.

Gantt ChartGantt Chart

Foundation

Framing

Plumbing

Electrical

Siding

Wall Board

Paint Interior

Paint Exterior

Fixtures

Activity Start 5 10 15 20 25 30 35 40 45 50Days After Start

Days After StartStart 5 10 15 20 25 30 35 40 45 50

Advantages of GanttAdvantages of Gantt

1.1. Easy to understandEasy to understand

2.2. Easy to constructEasy to construct

PERT AND CPMPERT AND CPM PERT (program evaluation and review PERT (program evaluation and review

technique) and CPM (critical path method) technique) and CPM (critical path method) are two of the most widely used techniques are two of the most widely used techniques for planning and coordinating large scale for planning and coordinating large scale projects.projects.

By using PERT or CPM managers are able to By using PERT or CPM managers are able to obtain:obtain: A graphical display of the project activitiesA graphical display of the project activities An estimate of how long the project will takeAn estimate of how long the project will take An indication of which activities are most criticalAn indication of which activities are most critical An indication of how long an activity can be An indication of how long an activity can be

delayed without lengthening the projectdelayed without lengthening the project

Network Models PERT & CPMNetwork Models PERT & CPM

PERT Initial use was for the Polaris Missile PERT Initial use was for the Polaris Missile Project - Late 1950sProject - Late 1950s

CPM was developed to plan and coordinate CPM was developed to plan and coordinate maintenance projects in chemical industry.maintenance projects in chemical industry.

Although two techniques were developed Although two techniques were developed independently, they have a great deal in independently, they have a great deal in common.common.

Initial differences between them have Initial differences between them have disappeared.disappeared.

Used to planning and controlling many Used to planning and controlling many programs & projects consisting of various programs & projects consisting of various activities (all activities be completed)activities (all activities be completed)

The framework of PERT and The framework of PERT and CPMCPM For proceeding with PERT/CPM following For proceeding with PERT/CPM following

common six points have to be followed:common six points have to be followed: Define the project with significant activities Define the project with significant activities

or tasksor tasks Develop relationship among the activitiesDevelop relationship among the activities Draw network connecting all activitiesDraw network connecting all activities Assign time and/or cost estimates to each Assign time and/or cost estimates to each

activityactivity Compute the critical pathCompute the critical path Use network to help plan, schedule, monitor Use network to help plan, schedule, monitor

and control the project and control the project

TerminologyTerminology ActivityActivity: A specific or set of tasks required by : A specific or set of tasks required by

the projectthe project EventEvent: Outcome of one or more activities: Outcome of one or more activities NetworkNetwork: Combination of all activities and : Combination of all activities and

eventsevents Path: Series of connected activities or Path: Series of connected activities or

between any two eventsbetween any two events Critical path: Longest - Any delay would Critical path: Longest - Any delay would

delay the projectdelay the project Slack/float: Allowable slippage for a path Slack/float: Allowable slippage for a path

PERT/CPM Type ProjectsPERT/CPM Type Projects

ConstructionConstruction EngineeringEngineering Software DevelopmentSoftware Development Anything with many interdependent Anything with many interdependent

activities/stepsactivities/steps

ActivitiesActivities Some may be executed Some may be executed

simultaneously simultaneously

Some cannot be performed until Some cannot be performed until others are completedothers are completed

DO THIS

AND AT THE SAME TIME DO THAT

CPM -Critical Path MethodCPM -Critical Path Method

A tool to determine duration based A tool to determine duration based on the identification of the on the identification of the Critical Critical PathPath through the activity network. through the activity network.

Times are known with some high Times are known with some high degree of certainty.degree of certainty.

Management can determine the Management can determine the duration of a project and concentrate duration of a project and concentrate efforts on efforts on Critical PathCritical Path activities. activities.

PERT Program Evaluation and PERT Program Evaluation and Review Technique Review Technique

Time are Time are NOTNOT known well known well (uncertainty)(uncertainty)

Statistics used to estimate Statistics used to estimate probability of finishing within a given probability of finishing within a given timetime

PERT/CPMPERT/CPM Activities are shown as lines or Activities are shown as lines or

arrowsarrows

Activities require time and other Activities require time and other recoursesrecourses

PERT/CPMPERT/CPM

Events or nodes or mileposts or circlesEvents or nodes or mileposts or circles They consume They consume NONO time and show time and show

connections between activitiesconnections between activities Every PERT/CPM chart has one Every PERT/CPM chart has one StartStart

event and one event and one endend event event

Simple CPM ChartSimple CPM Chart

START 1 END

Open Book Read Chapter

Calculating timesCalculating times

Time for top route = 2 + 4 + 4 + 3 = 13Time for top route = 2 + 4 + 4 + 3 = 13 Time for bottom route = 2 + 3 + 2 + 4 = Time for bottom route = 2 + 3 + 2 + 4 =

1111

START END

24

4

3

32

4

Critical PathCritical Path

Time for top route = 2 + 4 + 4 + 3 = 13Time for top route = 2 + 4 + 4 + 3 = 13 Time for bottom route = 2 + 3 + 2 + 4 = 11Time for bottom route = 2 + 3 + 2 + 4 = 11 Top is Critical pathTop is Critical path

START END

24

4

3

32

4

Slack timeSlack time

Time for top route = 2 + 4 + 4 + 3 = 13Time for top route = 2 + 4 + 4 + 3 = 13 Time for bottom route = 2 + 3 + 2 + 4 = 11Time for bottom route = 2 + 3 + 2 + 4 = 11

For activities For activities notnot on Critical path on Critical path Slack time = 2Slack time = 2

START END

24

4

3

32

4

No SLACK here

Slack timeSlack time

For activities not on critical path the slack For activities not on critical path the slack time is extra time that could be used is time is extra time that could be used is necessary necessary

If event B is reached in 6 days is there a If event B is reached in 6 days is there a significant problem? significant problem? No, not if the cause was the activity that should have taken 3 days took No, not if the cause was the activity that should have taken 3 days took 44

Yes, if the cause was the 2 day activity following start took 3 daysYes, if the cause was the 2 day activity following start took 3 days

START END

24

4

3

32

4B

3 time estimates3 time estimates Optimistic times (Optimistic times (aa)) Most-likely time (Most-likely time (mm)) Pessimistic time (Pessimistic time (bb))

Follow normal distributionFollow normal distribution Expected time: Expected time: tt = ( = (aa + 4 + 4mm + + bb)/6)/6 Variance of times: Variance of times: vv = (( = ((bb - - aa)) /6) /6) 22

PERT Activity TimesPERT Activity Times

A simple project network A simple project network diagramdiagram

----

1

2

3

4

5 6

Locate facilities

Interview

Order furniture

Remodel

Furniture setup

Hire & train

Move in

Activity relationshipActivity relationship

a

b

c

a b

c

a

b

c

d

a

b

c

Dummy Activity

a

b

c

d

1 2

3

4

(A)

(B)

(C)

(D)

Activity Immediate

Predecessors

A -

B -

C A

D A, B

1 2 3

5 4

Dummy Activity

A

B

D

C

2

4 51

3

(A) (B)

(C) (D)

(E)

Activity List for a Two-Machine Maintenance Project

Activity Description Expected Time (in days)

A Overhaul machine I 7

B Adjust machine I 3

C Overhaul machine II 6

D Adjust machine II 3

E Test system 2

2 5

71 4 8

3 6

Routing(C)

ProductDesign

(A)

MarketResearch

Plan(B)

Prototype(D)

MarketingBrochure

(E)

CostEstimates

(F)Testing

(G)

MarketSurvey

(H)

Pricingand

Forecast(I)

FinalReport

(J)

COMPLETION

Activity list for the Daugherty Porta-Vac Project

Activity Description ImmediatePredecessors

A R&D product design -B Plan market research -C Routing (manufacturing engineering) AD Build prototype model AE Prepare marketing brochure AF Cost estimates (industrial engineering) CG Preliminary product testing DH Market survey B, EI Pricing and forecast report HJ Final report F, G, I

PERT DiagramPERT DiagramActivity Preceding ActivityActivity Preceding Activity

A --A --B --B --C --C --D AD AE AE AF CF CG CG CH E, B, FH E, B, FII E, B, F E, B, FJ D, HJ D, HK G, I, JK G, I, J

2

4 61

3

E

5

B

C

G

J

K7

H

I

A

D

F

J

Sales Management Training Sales Management Training ProgramProgram

AA Plan topicPlan topic BB Obtain speakersObtain speakers CC List meeting locationsList meeting locations DD Select locationSelect location EE Speaker travel plansSpeaker travel plans FF Final check with speakersFinal check with speakers GG Prepare and mail brochurePrepare and mail brochure HH Take reservationsTake reservations II Last minute detailsLast minute details

Network DiagramNetwork Diagram

A B

C

D

G

E

H

F

1

2

3

4

5

6

7

I

8

Activities of a projectActivities of a projectActivity PActivity Predecessor redecessor

ActivityActivity

aa --

bb --

cc --

dd aa

ee b,cb,c

ff b,cb,c

gg b,cb,c

hh cc

II g,hg,h

jj d,ed,e

Network Diagram

1

2

4

3

6

5

7

a

b

c

d

ef

g

h

i

j

Make a Network DiagramMake a Network Diagram

1

3

4

2

6 7

5 8

9

10

11

A,6

H, 3

B, 2

C, 2

D, 3

K, 1

Q, 5

G, 9N, 3

K, 10

J, 3

I, 2

O, 5

Dum1

P, 4M, 10

E, 8

F, 5

AA ---- 66 BB ---- 77 CC ---- 88 DD AA 55 EE AA 66 FF AA 88 GG CC 55 HH CC 66 II B, G, FB, G, F 66 JJ B, G, FB, G, F 44 KK E, J, LE, J, L 33 LL I, HI, H 55 MM I, HI, H 44 NN L, E, JL, E, J 22 OO K, DK, D 44 PP M, N, OM, N, O 44

Network DiagramNetwork Diagram

1

2

3

4

7

6 8 9

5

A, 6

B, 7

C, 8

D, 5

E, 6F, 8

G, 5

H, 6

I, 6L, 5 M, 4

Dum

O, 4

P, 4J, 4N,2

ProblemProblem

I B, E, FI B, E, F

1

2

3

4

5

6

A (8)

B (10)

C (3)

D (7)

E (6)

G (5)

F (7) H (3)

(Activity time in days in parenthesis)

Questions??Questions?? Identify the critical pathIdentify the critical path How long will it take to complete this How long will it take to complete this

project?project? Can activity E be delayed without Can activity E be delayed without

delaying the entire project?delaying the entire project? Can activity D be delayed without Can activity D be delayed without

delaying the entire projec?, for how delaying the entire projec?, for how many days!many days!

What is the schedule for activity F (I.e., What is the schedule for activity F (I.e., start and completion times)start and completion times)

ExercisesExercises

Ex. 1Ex. 1

Draw a PERT Network, Identify Critical Draw a PERT Network, Identify Critical Path and Calculate Critical Time.Path and Calculate Critical Time.

ActivitiesActivities Preceding ActivitiesPreceding Activities Duration (Days)Duration (Days)

AA -------- 22

BB -------- 33

CC -------- 11

DD A,B,CA,B,C 44

EE DD 22

FF DD 33

GG DD 44

HH E,RE,R 22

II E,RE,R 22

JJ H,IH,I 11

OO II 11

KK E,F,GE,F,G 33

LL G,QG,Q 22

MM G,QG,Q 11

NN L,ML,M 33

PP N,K,O,JN,K,O,J 44

QQ A, B, CA, B, C 44

RR A, B, CA, B, C 33

1

2

3

4

5 7 11 14

8 12

13

6 10

9

A (2)

B(3)

C(1)

D(4)

R

Q

E(2)

F(3)

G(4)

I(2)

H(2)

J (1)

O(1)

K (3)

L (2)

M (1)

N (3)

P (4)

D1

D2

D3

D4

D6

D5

ExercisesExercises

Ex. 2Ex. 2

Take a Real World or Hypothetical Take a Real World or Hypothetical Project, Identify Activities, Estimate Project, Identify Activities, Estimate Activity Time and Draw a PERT Activity Time and Draw a PERT Network. Identify Critical Path and Network. Identify Critical Path and Calculate Calculate

CRITICAL PATH CALCULATIONSCRITICAL PATH CALCULATIONSThe critical path calculations include two phases. The first phase The critical path calculations include two phases. The first phase is called the is called the forward passforward pass, where calculations begin from the , where calculations begin from the

“start” node and move to the “end” node. At each node a “start” node and move to the “end” node. At each node a number is computed representing the earliest occurrence time of number is computed representing the earliest occurrence time of the corresponding event. These numbers are shown in Figure 13-the corresponding event. These numbers are shown in Figure 13-

5 in squares 5 in squares . The second phase, called the�. The second phase, called the� backward pass backward pass, , begins calculations from the “end” node and moves to the “start” begins calculations from the “end” node and moves to the “start” node. The number computed at each node (shown in triangles Δ) node. The number computed at each node (shown in triangles Δ) represents the latest occurrence time of the corresponding event. represents the latest occurrence time of the corresponding event.

The forward pass is considered now. The forward pass is considered now.

Let ESLet ESii be the be the earliest start time earliest start time of all the activities of all the activities emanating from event emanating from event ii . Thus ES . Thus ESii represents the earliest represents the earliest

occurrence time of event occurrence time of event ii. If . If ii = 0 is the “start” event, then = 0 is the “start” event, then conventionally, for the critical path calculations, ESconventionally, for the critical path calculations, ES00 = 0. Let D = 0. Let Dijij be the duration of activity (be the duration of activity (ii, , jj). The forward pass calculations are ). The forward pass calculations are

thus obtained from the formulathus obtained from the formula

ESESjj = max {ES = max {ESii + D + Dijij},}, for all (for all (ii, , jj) activities defined ) activities defined ii

Where ESWhere ES00 = 0. Thus, to compute ES = 0. Thus, to compute ESjj for event for event jj, ES , ES ii for the tail for the tail events of all the incoming activites(events of all the incoming activites(ii , , j j) must be computed first) must be computed first

The forward pass calculations applied to Figure 13-5 start with ESo = 0, as shown in the square above event 0. Since there is only one incoming activity (0, 1) to event 1 with D01 = 2,

ES1 = ESo + D01 = 0 + 2 = 2

which is entered in the square associated with event 1. Next, we consider event 2.[Notice that event 3 cannot be considered at this point, since ES2 (event 2) is not yetknown.] Thus

ES2 = ESo + D02 = 0 + 3 = 3

which is entered in the square associated with event 2. The next event to be con-sidered is 3. Since there are two incoming activities, (1, 3) and (2, 3), we have

ES3 = max {ESi + Di3} = max{2 + 2,3 + 3} = 6 1=1,2

which, again, is entered in the square of event 3.The procedure continues in the same manner until ESj is computed for all j.

Thus

These calculations complete the forward pass.These calculations complete the forward pass.The backward pass starts from the "end" event. The The backward pass starts from the "end" event. The

objective of this phase is to compute LCobjective of this phase is to compute LCii, , the latest completion the latest completion time for all the activities coming into event time for all the activities coming into event ii. Thus, if . Thus, if ii = = nn is the is the "end" event, LC"end" event, LCnn = ES = ESnn initiates the backward pass. In general, initiates the backward pass. In general, for any node for any node ii,,

LCLCii = min{LC = min{LCjj - D - Dijij, for all (, for all (i, ji, j) activities defined) activities definedThe values of LC (entered in the triangles The values of LC (entered in the triangles ΔΔ) are determined as ) are determined as follows.follows.

The backward pass calculations are now complete.The backward pass calculations are now complete.

The critical path activities can now be identified by using The critical path activities can now be identified by using the results of the forward and backward passes. An activity (i, j) the results of the forward and backward passes. An activity (i, j) lies on the lies on the critical pathcritical path if it satisfies the following three if it satisfies the following three conditions:conditions:

These conditions actually indicate that there is no float or slack time between ear-liest start (completion) and the latest start (completion) of the critical activity. In thearrow diagram these activities are characterized by the numbers in � and Δ beingthe same at each of the head and the tail events and that the difference between thenumber in �(or Δ) at the head event and the number in � (or Δ) at the tail eventis equal to the duration of the activity.

Activities (0, 2), (2, 3), (3, 4), (4, 5), and (5, 6) define the critical path in Figure 13-5.Actually, the critical path represents the shortest duration needed to complete the project. Notice that activities (2, 4), (3, 5), (3, 6), and (4, 6) satisfy conditions (1) and (2) for critical activities but not condition (3). Hence they are not critical. Notice also that the critical path must form a chain of connected activities that spans the network from "start" to "end."