Free Powerpoint Templates Page 1 Free Powerpoint Templates Project Scheduling Network formation Network Analysis Bar chart Resources Class 4

Free Powerpoint TemplatesPage 1

Free Powerpoint Templates

Project Scheduling

•Network formation•Network Analysis•Bar chart•Resources

Class 4

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Network Formation

• A project network is a tool used for planning, scheduling, and monitoring project progress.

• Network is a graphical representation of the project or part of it, showing all of the activities and their relationships.

• Network is developed from the information collected for the WBS.



Definition• Activity: is an element of the project that requires time,

may or may not require resources.• Path: is a sequence of connected, dependent activities• Critical Path: is the longest path(s) through the network,

if an activity on the path is delayed, the project is delayed the same amount of time.

• Event: This term is used to represent a point in time when an activity is started or completed. It does not consume time.

• Predecessor: activity must be completed before• Successor: activity must immediately follow it



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2

3

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5

START



Basic rules in developing project network

1. Networks flow typically from left to right.

2. An activity cannot begin until all preceding connected activities have been completed.

3. Arrows on networks indicate precedence and flow. Arrows can cross over each other.

4. Each activity should have a unique identification number.

13 15



5. An activity identification number must be larger than that of any activities that precede it.

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2

4

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5

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8

1

2

3

4

5

6

7

8



6. Looping is not allowed.

7. Condition statements are not allowed.

8. When there are multiple starts, a common start node can be used to indicate a clear project beginning on the network.

A

B

Y

Z

Dummy

Dummy



Project Networks

There are 2 types:-

1. Activity-on-Arrow (AOA) / Arrow Diagram

2. Activity-on-Node (AON) / Precedence Diagram



Arrow Diagrams

• The arrow diagram represents an individual project activity that requires time.

• Arrow diagrams were the first form of network diagram to be developed.

• The length and slope of the arrow diagram have no significance.



Activities and Events

Activities are represented by arrows starting and terminating at nodes or events.

START FINISH

ACTIVITY



Predecessor-Successor Relationships

Time relationships between activities is indicated by connecting activities through events.

ACTIVITY1 ACTIVITY2

ACTIVITY1 ACTIVITY3

ACTIVITY2(2 sources)



Concurrence Relationships

Some activities can be performed at the same time, referred to as concurrent activities.

ACTIVITY1

ACTIVITY2



Dummy Activities

Sometimes the logic of the operation cannot be adequately described using only real activities and dummy activities need to be created.

ACTIVITY1 ACTIVITY3

ACTIVITY2 ACTIVITY4



ACTIVITY2

ACTIVITY1 • Dummy activities have no duration, cost nothing, and use no resources.

• Dummy activities are normally drawn using dotted lines.



Artificial Activity

An artificial activity is used to create a delay. It has a duration, but no cost or resources.

Circuits

As such circuits or loops are not possible, should avoid.



Aggregated Activity

Occasionally it is conventional to group a collection of activities and replace this group with a single activity.

A

B

C

D

H

F

G

E



Example – Arrow diagram

Activity Predecessor

A -

B -

C A

D B

E B

F C, D

G E



Case#1 Arrow diagramActivity Preceding

ActivityActivity Times

A - 5

B A 15

C A 10

D A 5

E B, C 15

F B, C, D 10

G F 170

H E, G 35



Case#2 Arrow diagramActivity Preceding

Activity

A -

B -

C A, B

D A, B

E A, B

F C, D

G E

H F

I F, G



Case#3 Bridge building – Arrow diagramActivity Code

Operation Dependence Duration

ENA Earthworks, north side - 5

ESA Earthworks, south side ENA 4

CONN Construction, north side ENA 14

CONS Construction, south side ESA, CONN 12

COMN Compaction, north side CONN 2

COMS Compaction, south side CONS, COMN 2

RNB Road, north of bridge COMN 2

RSB Road, south of bridge RNB, COMS 2

PB Prefabrication bridge deck - 18

TD Transport deck to site PB 2

EB Erect bridge deck TD, CONN, CONS, COMN 3

LBS Lay bridge surface EB, RNB, RSB 2

ICB Install crash barriers EB 1

L Landscape RNB, RSB 1



Precedence Diagrams

• In this diagram the nodes represent the activities and the arrows give the precedence relationships between them.

• Widely availability if personal computers and graphics programs



AOA to AONA B

A

B

C

D

E



A B D

C

A B

C D



A B

C

D



Example – Precedence diagramActivity Predecessor

A -

B -

C A

D B

E B

F C, D

G E



Case#4 Precedence diagram

Activity Preceding Activity

Activity Times

A - 5

B A 15

C A 10

D A 5

E B, C 15

F B, C, D 10

G F 170

H E, G 35



Case#5 Precedence diagramActivity Preceding

Activity

A -

B -

C A, B

D A, B

E A, B

F C, D

G E

H F

I F, G



Case#6 Bridge building – Precedence diagram

Activity Code

Operation Dependence Duration

ENA Earthworks, north side - 5

ESA Earthworks, south side ENA 4

CONN Construction, north side ENA 14

CONS Construction, south side ESA, CONN 12

COMN Compaction, north side CONN 2

COMS Compaction, south side CONS, COMN 2

RNB Road, north of bridge COMN 2

RSB Road, south of bridge RNB, COMS 2

PB Prefabrication bridge deck - 18

TD Transport deck to site PB 2

EB Erect bridge deck TD, CONN, CONS, COMN 3

LBS Lay bridge surface EB, RNB, RSB 2

ICB Install crash barriers EB 1

L Landscape RNB, RSB 1



Comparison of AON and AOA

AOA methodAdvantages:1. Path tracing is simplified by activity/event numbering

scheme2. AOA is easier to draw if dependencies are intense3. Key events or milestones can easily be flaggedDisadvantages:4. Use of dummy activities increases data requirements5. Emphasis on events can distract from activities



AON methodAdvantages:1. No dummy activities are used2. Events are not used3. AON is easy to draw if dependencies are not intense4. Activity emphasis is easily understand by first-level

managersDisadvantages:5. Path tracing by activity number is difficult6. Network drawing and understanding are more difficult

when dependencies are numerous



Network Analysis

The Critical Path is the minimum time that it takes to complete a

projectis the longest sequence of activities in the network• There maybe more than one critical path through

a network; but one is better• The activities that lie along critical path are

called critical activities• If a critical activity is delayed then the whole

project is delayed



10

15 15

20

30

25 510

How long does it take to finish this project?

Where is critical path?



Case#7 Critical Path


Activity Times

A - 5

B A 15

C A 10

D A 5

E B, C 15

F B, C, D 10

G F 170

H E, G 35



Case#8 Critical Path

ID Description Predecessor Time

A Survey - 5

B Soils report A 20

C Traffic design A 30

D Lot layout A 5

E Approve design B, C, D 80

F Illumination E 15

G Drainage E 30

H Landscape E 25

I Signing E 20

J Bid proposal F, G, H, I 10

A city requests federal funding for a par-and-ride project. Network plan is to be submit. Make the critical path.



Analysing Network

EST – earliest start time

LST – latest start time

EFT – earliest finish time

LFT – latest finish time

TF –Total float

FF – Free float

IF – Interfering float



• Earliest times: are the earliest times that an activity can start and finish given that all preceding activities as soon as possible

• Latest times: are the latest that an act can start and finish and still allow time for succeeding activities to be completed without holding up the project

• TF = LST-EST = LFT – EFT

is the amount of time that an act can be delayed without effecting the overall duration

Critical path; TF = 0



• FF: is the amount of time that an activity can be delayed without affecting any other activity

• IF = TF –FF

will affect succeeding activities but not the total project duration

10

20 20



10

20

10

15

10

EST EFT

LST LFT

FF TF



10

15

20

20

30

20

EST EFT

LST LFT

FF TF



Bar charts

• Also known as a Gantt bar chart• Gives a pictorial representation of when

the activities begin, when they end, how long they take and how much float they have



Overlapping relationshipsPreceding Activity

Following Activity

Start to Start

Start to Finish

Finish to Start

Finish to Finish

S/S

S/F

F/S

F/F

• Length of the arrows represents the lead times (LT)

• Overlapping makes project faster



RESOURCES

• Resources are the things that are needed to carry out project activities

• Main resources:-

Man – workers, Engineers, Proj. Man.

Machine – pumps, cranes

Materials – steel, pipe, bolts&nuts• Why manage resources:-

1. Resource Constrained Scheduling

2. Resource Leveling



1. Resource Constrained Scheduling

• Limited resources• Sometimes resources are restricted; some

activities need to be delayed because of not enough resources

• Where schedule is constrained by the available resources and may have to increase the duration of the project



Reasons for resource limited:• Space constraints• Limited facilities• Safety requirements limit• Limited amount of equipment to work onSolutions:• Working overtime• Working shifts• Training, education, automation = increase productivity• Learning curve = repetitive• Hire sub-contractors• Reduce scope of work



Resources

Time

Resource limited

Extend Project duration



2. Resource Leveling

• Hiring & Firing• Resources cost money even though no work is being

done• A uniform resource usage will prevent resources being

idle and to minimize hiring and firings• Safety, learning curve, skilled workers, happy, lower

price, more work, more profit• Duration of project is limited• No one approach is accepted as the best



Resources

Time

Time limited

• Rearrange activities within project duration• Moving activities around in order to smooth the resource profile



A

B

C

D

5days, 3men

3days, 2men

4days, 4men

5days, 2men




Activity Times Resources

A - 6 3

B - 4 3

C - 3 2

D A 2 4

E A, B 3 1

F B, C 5 1

G D, C 3 2

H E, F 2 2

I C, H 4 2

J G 3 3



Example

a) Draw an arrow diagram

b) Analyze network giving EST, EFT, LST, LFT, FF and TF

c) Construct a resource profile

d) Assuming that you only have 6 units of resource; reschedule the activities to fit the resource limitations



Activity Follows Duration (days)

Resource

A - 8 2

B - 10 4

C - 12 1

D A 20 3

E A 5 4

F C 16 2

G C 13 0

H D 14 1

I B, D, E, F 8 1

J B, E, D, F, G 16 0



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Free Powerpoint Templates Page 1 Free Powerpoint Templates Project Scheduling Network formation Network Analysis Bar chart Resources Class 4