The network-diagram-and-critical-path-adapted

DEVELOPMENT OF THE NETWORK DIAGRAM AND

CRITICAL PATHAdapted and edited from

A Practical Introduction to Management Science

4th edition

BUILDING A HOUSE

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THE NETWORK DIAGRAM IS

ABOUT CREATING

RELATIONSHIPSBETWEEN ACTIVITIES

THE NETWORK DIAGRAM IS

ABOUT CREATING

RELATIONSHIPSBETWEEN ACTIVITIES

BUILDING A HOUSE

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RELATIONSHIPS ARE ALSO

REFERRED TO AS DEPENDENCIES – THE MOST BASIC

IS “FINISH TO START”

RELATIONSHIPS ARE ALSO

REFERRED TO AS DEPENDENCIES – THE MOST BASIC

IS “FINISH TO START”

BUILDING A HOUSE

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THUS THE BASIC QUESTION IS

WHICH ACTIVITIES MUST

BE FINISHED BEFORE WHICH ACTIVITIES CAN

START

THUS THE BASIC QUESTION IS

WHICH ACTIVITIES MUST

BE FINISHED BEFORE WHICH ACTIVITIES CAN

START

BUILDING A HOUSE

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THE USE OF AN ARROW

(SPECIFICALLY IN THE NOTATION USED IN THIS

EXAMPLE) SHOWS THIS

RELATIONSHIP

THE USE OF AN ARROW

(SPECIFICALLY IN THE NOTATION USED IN THIS

EXAMPLE) SHOWS THIS

RELATIONSHIP

A B

Activity A Must Be Finished Before B Can Start

BUILDING A HOUSE

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THE USE OF AN ARROW

(SPECIFICALLY IN THE NOTATION USED IN THIS

EXAMPLE) SHOWS THIS

RELATIONSHIP

THE USE OF AN ARROW

(SPECIFICALLY IN THE NOTATION USED IN THIS

EXAMPLE) SHOWS THIS

RELATIONSHIP

But Activity E, F and G Don’t Have to Wait for Each Other

D

E

F

G

FrameHVAC

Rough Electric

H

Sheet Rock

BUILDING A HOUSE

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THE USE OF AN ARROW

(SPECIFICALLY IN THE NOTATION USED IN THIS

EXAMPLE) SHOWS THIS

RELATIONSHIP

THE USE OF AN ARROW

(SPECIFICALLY IN THE NOTATION USED IN THIS

EXAMPLE) SHOWS THIS

RELATIONSHIP

Note That E, F and G Don’t Have to Start and Finish At The Same Time

D

E

F

G

FrameHVAC

Rough Electric

H

Sheet Rock

BUILDING A HOUSE

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THE USE OF AN ARROW

(SPECIFICALLY IN THE NOTATION USED IN THIS

EXAMPLE) SHOWS THIS

RELATIONSHIP

THE USE OF AN ARROW

(SPECIFICALLY IN THE NOTATION USED IN THIS

EXAMPLE) SHOWS THIS

RELATIONSHIP

They However Need to Be Finished Before H Can Start

D

E

F

G

FrameHVAC

Rough Electric

H

Sheet Rock

Task 1 Is to Create These Dependencies By Listing the Steps That Happen Before Each Activity

SUMMARY OF ACTIVITIES

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Time ImmediateRequiredPredecessor

Activity Description (in days) ActivitiesA ExcavateB Lay foundationC Rough plumbingD FrameE Finish exteriorF Install HVACG Rough electricH Sheet rockI Install cabinetsJ PaintK Final plumbingL Final electricM Install flooring

SUMMARY OF ACTIVITIES

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Time ImmediateRequiredPredecessor

Activity Description (in days) ActivitiesA Excavate --B Lay foundation AC Rough plumbing BD Frame BE Finish exterior DF Install HVAC DG Rough electric DH Sheet rock C, E, F, GI Install cabinets HJ Paint HK Final plumbing IL Final electric JM Install flooring K, L

Task 2 TEST THE LOGIC BY CONSTRUCTING

THE NETWORK DIAGRAM

An Activity-On-Node (AON) Network

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Install Cabinets

A B

C

D

E

F

G

H

I

J

K

L

M

Excavate

Lay Foundation

Rough Plumbing

Frame

Finish Exterior

HVAC

Rough Electric

Sheet Rock

Paint

Final Plumbing

Final Electric

InstallFlooring

Basic Rules for Constructing the Network Diagram

•Networks typically flow from left to right;

•An activity cannot begin until all of its preceding activities are complete;

•Arrows indicate precedence and flow and can cross over each other;

•Identify each activity with a unique number; this number must be greater than its predecessors;

•Looping is not allowed;•Use unique start and stop nodes.

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Task 3 DETERMINE DURATIONS FOR EACH

ACTIVITY

SUMMARY OF ACTIVITIES

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Time ImmediateRequiredPredecessor

Activity Description (in days) ActivitiesA Excavate 3 --B Lay foundation 4 AC Rough plumbing 3 BD Frame 10 BE Finish exterior 8 DF Install HVAC 4 DG Rough electric 6 DH Sheet rock 8 C, E, F, GI Install cabinets 5 HJ Paint 5 HK Final plumbing 4 IL Final electric 2 JM Install flooring 4 K, L

SUMMARY OF ACTIVITIES

• Time Immediate• Required Predecessor• Activity Description (in days) Activities• A Excavate 3 --• B Lay foundation 4 A• C Rough plumbing 3 B• D Frame 10 B

• In this chart we read that:Activity A (excavating the property) takes 3 days to complete.Activity B (lay foundation) takes 4 days to complete but can not start until

Activity A is complete. So from start to finish of Activity B takes 7 days.

Activity C (rough plumbing) takes 3 days to complete but Activity B must be completed first. To complete Activity B, Activity A must be complete. Total time from start to end of Activity C takes 10 days.

Activity D (frame) takes 10 days to complete but can not be completed until Activity B is complete. In this case, you do not need to have Activity C complete to finish Activity D.

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Look at this a different way

• Let’s go back to the house idea.• If you want to build a house what is the first

thing you want to do?• Do you buy the materials and then start building?• Do you dig the foundation and start pouring

cement?• Do you buy the curtains, carpet, drapes, and

windows?

• No, the first thing you do is decide on the type of house you want and what it should look like.

• If you just start building you may end up with a house you really didn’t want.

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The first mistake of project management

•There is an old saying that goes, “if you don’t know where you are going, any road will get you there.”

•There is another line that goes, “if you don’t know where you are going, how will you know if you even got there?

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The first mistake of project management

•Many projects fail because the teams do not know what they want.

•Teams don’t start with a vision of what it will look like, they start with what they have and start to build.

•The problem is that when you start to put the project together you may not be able to take one step and make it match the next step.

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The first mistake of project management

•Think about building an instrument for a spacecraft and after it is built finding out that the power supply isn’t correct for the instrument.

•Believe it or not, this has happened many times.

•One group started a project and at every step change had to make major changes to what they had just done. This caused delays and cost more money.

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In CPM you build from the future to the present

• You don’t build a house unless you know what it is going to look like.

• In a project you do not start unless you know what you want it to look like or what you want it to do.

• You start with the finished product and figure out what steps it will take to complete each step.

• In the case of a house, you figure out what the outer shape will be, what the roof will look like, what it will take to build the roof and the walls, what will have to go inside the walls, what the floor will look like…..

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What does this mean for you?

•As you work through this course:▫Think about what you want▫Think about what steps will need to be

taken to get what you want▫Think about the order for the steps▫Think about if the steps will actually

connect to each other efficiently▫Draw a diagram showing the steps, what

the step looks like when it is complete, and who will be responsible for that step

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