precedence diagramming

7/29/2019 Precedence Diagramming

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1

Precedence Diagramming



2

Work Breakdown Structure (WBS)• A deliverable oriented hierarchical decomposition of the work to be executed

by the project team to accomplish the team mission and create the required

deliverables. The WBS defines the project scope.

Scheduling Terminology

Team Mission



3

Deliverable• Any unique and verifiable product or result that must be produced to

complete a project. Usually the lowest level of the WBS.


Team Mission



4

Scheduled Activity (task)• A component of work performed to create a deliverable.


Team Mission

Task 1

Task 2

(Etc.)

Task 1

Task 2

(Etc.)

Task 1

Task 2

(Etc.)

Task 1

Task 2

(Etc.)

Task 1

Task 2

(Etc.)

Task 1

Task 2

(Etc.)

W B S

( S c o p e )

A

c t i v i t y L i s t

( S c h e d u l e )



5

Duration• Total number of work periods required to complete a scheduled activity.

Usually expressed as workdays. (contrast with “effort”)

•Effort• Total number of labor units requird to complete a scheduled activity.

Usually expressed as staff hours or a rate. (contrast with “duration”)

•Schedule Milestone• A significant event in the project schedule, such as an event restrainingfuture work or marking the completion of a major deliverable. A “measuring

point”. Milestones have “0” (zero) duration and no resource assignments.




6

Basic Bar Chart

(Gantt Chart)



7

Defining Activities/Tasks

•Definition

• Assignment

•

Significance



8

Task InterdependenciesSpecify Task Relationships

All tasks are Related To:

• Other Schedule Activities

– “Mandatory” or “Hard Logic”

– “Discretionary” or “Soft Logic”

• External Events

– Dependent Dates

– Required Dates

Network Diagram

Task Interdependencies



9

• FS –

Finish Start

Start

Finish

• SS – Start Start

• FF – Finish Finish

Start

Finish

Types of Task Relationships

Finish Start



10

• Lead and Lag are used to Modify Relationships• Lead and Lag Can be used with any Relationship Type

(FS, FF, SS)

NormalFinish - Start

Leads and Lags

Finish – StartModified by a Lead

Finish – StartModified by a Lag



11

Arrow Diagram Method (ADM)(aka Activity on Arrow – AOA)

•Tasks represented by arrows (length not related to duration)

•Dependency shown as node

•Only F-S relationship used

•Archaic

– not used with current software

1

2

6

7

8

3

5

4

“Dummy task” used to complete logic, duration of “0”



12

Precedence Diagram Method

(PDM)(aka Activity on Node – AON and Network Diagram)

•Tasks represented by nodes

•Dependency shown as arrows or links between nodes

•All task relationships can be used (FS, FF, SS)

•Basis for all current software applications

A

B

C

D

E

F

G



13

Critical Path

•Sequence of scheduled activities that determines the projectduration

•Longest duration path through the project network

•Activities on the Critical Path are called “Critical Activities”

•Critical activities have no float or slack

•A project can have more than one critical path

•Activities not on the Critical Path are called “Non Critical

Activities

•To shorten the project duration, a scheduler must modify the

critical path activities or dependencies



14

•Total Float – the total amount of time through a path of

activities that may be delayed or extended without delayingthe project end date or violating a schedule constraint.

•Free Float – the amount of time within an activity (or milestone) tha can be delayed without delaying the start of the

next activity in the network.

• Negative Float – the amount of time that by which a critical

activity (or milestone) misses a required date.

Float (or Slack)



15

Critical Path Method

1. Calculate Early Start & Early Finishdates (FORWARD PASS)

2. Calculate Late Start & Late Finish dates(BACKWARD PASS)

3. Calculate TOTAL FLOAT for each

activity4. Identify activities with 0 (zero) TOTALFLOAT



16 Activity Node

WBS Code Activity

Late Start (LS)

Late Finish (LF)

Early Start (ES)

Early Finish (EF)

Total Float (TF)

Duration



17

Activity A WBS Code Activity

Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

7

Activity BWBS Code Activity

Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

5

Activity CWBS Code Activity

Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

2

Activity DWBS Code Activity

Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

3

Activity EWBS Code Activity

Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

3

Simple Project consisting of 5 Tasks



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Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

7


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

3

TWO THINGS

NEEDED TO SET

PROJECT START& END DATE

1. First and last activities

(milestones)

2. Activity durations

1



19




3. Calculate TOTAL FLOAT for eachactivity

4. Identify activities with 0 (zero) TOTALFLOAT

6



20


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

7


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

5


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

2


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

3


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

3

Project Start Date & Task Durations are known

1



21


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

7


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

5


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

2


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

3


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

3

Early Finish = Early Start + Duration

18



22


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

7


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

5

Activity C

WBS Code Activity

Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

2


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

3


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

3

Early Start With Single Predecessor

18

8

8

13

10



23


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

7


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

5

Activity C

WBS Code Activity

Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

2


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

3


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

3

Early Start With Multiple Predecessors

18

8

8

13

10

13

16



24


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

7


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

5

Activity C

WBS Code Activity

Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

2


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

3


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

3

Start-to-Start Relationships (A to E)

18

8

8

13

10

13

16

1

4



25


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

7


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

5

Activity C

WBS Code Activity

Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

2


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

3


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

3

Completed FORWARD Pass

18

8

8

13

10

13

16

1

4



26








27


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

7


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

5

Activity C

WBS Code Activity

Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

2


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

3


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

3

Start the BACKWARD Pass

18

8

8

13

10

13

16

1

4

16

The last activity

Early Finish

(EF) will default

to be the LateFinish (LF).



28


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

7


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

5

Activity C

WBS Code Activity

Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

2


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

3


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

3

Late Start (LS) = Late Finish (LF) - Duration

18

8

8

13

10

13

16

1

4

16

13



29


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

7


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

5

Activity C

WBS Code Activity

Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

2


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

3


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

3

Late Starts with Single Successors

18

8

8

13

10

13

16

1

4

16

13

13

13

11

8



30


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

7


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

5

Activity C

WBS Code Activity

Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

2


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

3


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

3

Late Start with Multiple Successors

18 8

8

13

10

13

16

1

4

16

13

13

13

8

11

81



31


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

7


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

5

Activity C

WBS Code Activity

Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

2


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

3


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

3

Finish-to-Finish Relationships (D to E)

18 8

8

13

10

13

16

1

4

16

13

13

13

8

11

81

16

13



32


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

7


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

5

Activity C

WBS Code Activity

Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

2


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

3


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

3

Completed BACKWARD Pass

18 8

8

13

10

13

16

1

4

16

13

13

13

8

11

81

16

13



33






6



34


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

7


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

5

Activity C

WBS Code Activity

Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

2


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

3


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

3

Total Float (TF) = Late Finish (LF) – Early Finish (EF)

18 8

8

13

10

13

16

1

4

16

13

13

13

8

11

81

16

13

0

0

0

12

3



35






6



36


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

7


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

5

Activity C

WBS Code Activity

Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

2


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

3


Early Start (ES)

Early Finish (EF)

Late Start (LS)

Late Finish (LF)

Duration

Total Float (TF) =

3

Critical Path – Tasks with no Total Float (TF)

18 8

8

13

10

13

16

1

4

16

13

13

13

8

11

81

16

13

0

0

0

12

3



37

Task A

2 days

Task B

3 days

Task C

1 days

Task D

2 days

Task E

4 days

Task F

5 days

Task G

2 days

Start Fin

St – A – C – F – Fin: ________

St – B – D – G – Fin: ________

St – B – E – G – Fin: ________

8 days

7 days

9 days



38

Task A

4 days

Task B

6 days

Task D

5 days

Task E

10 days

Task F

5 days

Task H

7 days

Task J

2 daysStart Fin

Task C

8 daysTask G

8 days

St – A – D – H – Fin: ________

St – B – E – J – Fin: ________

St – C – F – J – Fin: ________

St – C – G – Fin: ________

16 days

18 days

15 days

16 days



39

Activity Duration Preceding Activity

Start (Milestone) 0 --

Task A 4 days Start

Task B 3 days Start

Task C 5 days Task A

Task D 7 days Task B

Task E 3 days Task B

Task F 10 days Task C & Task D

Task G 4 days Task D & Task E

Task H 2 days Task E

Task I 2 days Task F & Task GTask J 4 days Task H

Finish (Milestone) 0 Task I & Task J



40

St – A – C – F – I – Fin: ________

St – B – D – F – I – Fin: ________

St – B – D – G – I – Fin: ________

St – B – E – G – I – Fin: ________

S B E H J Fi

12 days

16 days

22 days

21 days

Task C

5 daysTask A

4 days

Start

Fin

Task B

3 days

Task D

7 days

Task E

3 days

Task F

10 days

Task G

4 days

Task H

2 days

Task J

4 days

Task I2 days

12 d

precedence diagramming

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