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Project SchedulingProject Scheduling

IENG 321IENG 321

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OutlineOutline

What is a “project”?What is a “project”?

Objectives and tradeoffsObjectives and tradeoffs

Planning and Control in ProjectsPlanning and Control in Projects

Scheduling MethodsScheduling Methods

Constant-Time NetworksConstant-Time Networks

Precedence Diagramming MethodPrecedence Diagramming Method

PERT and CPM MethodsPERT and CPM Methods

Use of Project ConceptsUse of Project Concepts

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What is a “Project”?What is a “Project”?

Distinguishing characteristics of projectsDistinguishing characteristics of projects

ExampleExample

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Examples of Projects (Table 14.1)Examples of Projects (Table 14.1)

Building construction Movie making

New product introduction Teaching a course

Research and development Designing an advertising campaign

Computer system design Startup or shutdown of plant

Installation of equipment Manufacture of aircraft, ships, and largemachines

Space shots Auditing accounts

Fund-raising Planning a military invasion

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Objectives and TradeoffsObjectives and Tradeoffs

Meet thespecifications

Meet thedeadline

Due Date!

Stay withinthe budget

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Project Management Activities and Project Management Activities and DecisionsDecisions

Planning

Scheduling

Project

Control

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PlanningPlanning

Identify the project customerIdentify the project customer

Establish the end product or serviceEstablish the end product or service

Set project objectivesSet project objectives

Estimate total resources and time requiredEstimate total resources and time required

Decide on the form of project organizationDecide on the form of project organization

Make key personnel appointmentsMake key personnel appointments

Define major tasks requiredDefine major tasks required

Establish a budgetEstablish a budget

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SchedulingScheduling

Develop a detailed work-breakdown Develop a detailed work-breakdown structurestructure

Estimated time required for each taskEstimated time required for each task

Sequence tasks in proper orderSequence tasks in proper order

Develop a start/stop time for each taskDevelop a start/stop time for each task

Develop detailed budget for each taskDevelop detailed budget for each task

Assign people to tasksAssign people to tasks

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ControlControl

Monitor actual time, cost, and performanceMonitor actual time, cost, and performance

Compare planned to actual figuresCompare planned to actual figures

Determine whether corrective action is Determine whether corrective action is neededneeded

Evaluate alternative corrective actionsEvaluate alternative corrective actions

Take appropriate corrective actionTake appropriate corrective action

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Gantt Chart Project Example (Figure 14.1)Gantt Chart Project Example (Figure 14.1)

10/21 10/28 11/4 11/11 11/18 11/25 12/2

Dig basement

Pour footing

Lay block

Finish base work

Install main floor

Erect frame

Secure sheathing

Install roof boards

Install windows

Finish frames

Activity

Milestone

1 2 3 4 5 6 7

Week

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Network Project Chart (Figure 14.2)Network Project Chart (Figure 14.2)

Start 4 10

Digbasement

Pourfooting

Lay blockfoundation

Install mainfloor

Erectframe

Finish below-grade work

Secure outsidesheathing

Install roof

boards

Install windows

1 2 3 5 6

7

8

9

Finishrough-in

frame

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Constant-Time NetworksConstant-Time Networks

Activity times assumed to be constantActivity times assumed to be constant

““DummyDummy” activities” activities

Notations used in calculating start and finish Notations used in calculating start and finish times:times:– ES(a) =ES(a) = Early Start of activity aEarly Start of activity a– EF(a) =EF(a) = Early Finish of activity aEarly Finish of activity a– LS(a) =LS(a) = Late Start of activity aLate Start of activity a– LF(a) =LF(a) = Late Finish of activity aLate Finish of activity a

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Network Diagram (Figure 14.3)Network Diagram (Figure 14.3)

1

2

4

3

3

4

5

61 Event

Activity

2

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Dummy Activity Situations (Figure 14.4a)Dummy Activity Situations (Figure 14.4a)

F H

G

E

a. Activities F and G havethe same predecessor (E)and the same successor (H)

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Dummy Activity Situations (Figure Dummy Activity Situations (Figure 14.4b)14.4b)

E

A

B

C

D

b. Activity A and B have a commonpredecessor (E), but they have differentpredecessors (C and D)

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Dummy Activity Situations (Figure Dummy Activity Situations (Figure 14.4c)14.4c)

C

D

I

K

J

c. Activities C and D have acommon successor (K), butdifferent successors (I and J)

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Calculating ES, EF, LS, LF, and Completion Calculating ES, EF, LS, LF, and Completion TimeTime

ES (a) = 0 for the starting activity

EF (a) = ES (a) + t (a)*

ES (a) = max [EF (all predecessors of a)]Project completion time = max [EF(all ending activities)]

* t (a) denotes the duration of activity a

LF (a) = min [LS (all successors of a)]

LS (a) = LF - t(a)*

Forward Pass:

Backward pass:

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Slack TimesSlack Times

Total Slack Time (TST):Total Slack Time (TST): LS (a) - ES (a) - EF (a)= LF(a) - EF(a)LS (a) - ES (a) - EF (a)= LF(a) - EF(a)

Free Slack Time (FST)Free Slack Time (FST)min [ES (all successors of a)] - EF (a)min [ES (all successors of a)] - EF (a)

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Activity Start and Finish Times (Figure 14.5)Activity Start and Finish Times (Figure 14.5)

1

2

4

3 [ES, EF]

[LS, LF]

[0, 3] 3

[0, 3]

[3, 8] 5[3, 8]

[5, 7] 2

[6, 8]

[0, 4] 4[2, 6][3

, 5]

2[4

, 6]

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Activity Times (Table 14.3)Activity Times (Table 14.3)

Activity ES EF LS LFTotalSlack Free Slack

1-2 0 3 0 3 0 0

1-3 0 4 2 6 2 1

2-3 3 5 4 6 1 0

2-4 3 8 3 8 0 0

3-4 5 7 6 8 1 1

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PDM Network (Figure 14.6)PDM Network (Figure 14.6)

Activity1-2

Activity2-4

Activity2-3

Activity3-4

Activity1-3

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PDM Time Schedule (Figure 14.7)PDM Time Schedule (Figure 14.7)

0 1 2 3 4 5 6 7 8

2-4

1-2

2-3

1-3 3-4 Pro

ject

Com

plet

ion

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PDM Precedence RelationshipPDM Precedence Relationship

A B

Finish to StartJob B can start no sooner than3 days after Job A is completed.

FS = 3 A B

Start to StartJob B can start no sooner than2 days after Job A has started.

SS = 2

A B

Finish to FinishJob B can finish no sooner than4 days after Job A was finished.

FF = 4 A B

Start to FinishJob B can finish no sooner than6 days after Job A has started.

SF = 6

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Cement Floor Example (Figure 14.9)Cement Floor Example (Figure 14.9)

Installforms

Pourcement

FF = 0

SS = 1

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Time-Cost Relationship in CPMTime-Cost Relationship in CPM

Crash Cost

Cost

Normal Cost

Crash

Time

Normal

TimeTime

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Use of Project Management Use of Project Management ConceptsConcepts

Scheduling is only part of a Scheduling is only part of a completecomplete approach to project managementapproach to project management

Tradeoffs between sophistication and cost Tradeoffs between sophistication and cost of methodsof methods

Choice between PERT, CPM, and PDMChoice between PERT, CPM, and PDM

Project management softwareProject management software