instructional objective
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Module 7 Planning and Scheduling with the Critical Path Method Session 7.1: Planning tools and the critical path method (CPM). Instructional Objective. To prepare a critical path network plan for projects or subprojects. Overview. Planning activities Scheduling resources and - PowerPoint PPT PresentationTRANSCRIPT
Module 7 Session 7.1 Visual 1
Module 7
Planning and Scheduling with the Critical Path Method
Session 7.1: Planning tools and the critical path method (CPM)
Module 7 Session 7.1 Visual 2
Instructional Objective
To prepare a critical path networkplan for projects or subprojects
Module 7 Session 7.1 Visual 3
Overview
Planning activities
Scheduling resources and
Controlling progress
Module 7 Session 7.1 Visual 4
On-the-job tasks
Review the WBS, responsibility matrix, master summary schedule, and level of detail
Select the appropriate scheduling tool (typically time-scaled, precedence network diagram)
Disaggregate summary activities on the master summary schedule into activities and prepare activity list(s)
Assign responsibility and resource to each activity
Module 7 Session 7.1 Visual 5
On-the-job tasks (continued)
Estimate the duration of each activity
Establish the sequence of activities
Prepare the time-scaled precedence network diagram (or other form of schedule)
Determine the critical path
Calculate the activity float
Revise as required
Module 7 Session 7.1 Visual 6
What is planning ?
Who ?
Does what?
When ? and
How long will it take?
With what inter-relationships?
Module 7 Session 7.1 Visual 7
Why is planning important ?
Coordination
Control
Communication
Commitment
Module 7 Session 7.1 Visual 8
A cargo ship: an analogy
Start of journey
Destination
Course set in
itially
Module 7 Session 7.1 Visual 9
A cargo ship: an analogy
Externalinfluence
Res
et c
ours
e
Actual travelPosition surveyed
Start of journey
Destination
Course set in
itially
Module 7 Session 7.1 Visual 10
Planning tools
Activity lists
Bar chart (Gantt)
Network diagram family
Module 7 Session 7.1 Visual 11
Planning tools
Network diagram family
Critical path method (CPM)
Precedence diagram (PDM)
Time-scaled precedence diagram
Arrow diagram
PERT diagram
Module 7 Session 7.1 Visual 12
Master summary schedule House deliverable
Plan (A)
Site (C)
Foundation (C)
Frame (C)
Roof (SC)
Systems(SC) Plumbing (P) Electrical (E) Telephone (T)
Project mgt (PM)
4 8 12 16 20 24
WEEKS
Prepare
Construct
Construct
Construct
Prepare
Install
Continuous activity
From WBS summary activities or sub-projects or work package
CODE RESP.
10
20
30
40
50
60
70
Module 7 Session 7.1 Visual 13
Rolling wave subnets
MastersummaryscheduleT
od
ay
Start Finish
Detailed network for next period
Each monthadd a month
Each monthdrop a month
3-6 months
Level of detailmonths or weeks
Level of detailweeks or days
Module 7 Session 7.1 Visual 14
Guidelines for creating activities Disaggregate summary activities into activities Use “rolling wave” approach for long projects Use unit of time based on and less than previously
established control period Use verb (action) and a noun (the thing affected), for
example, buy land Assign responsibility to only one organization or
individual Assign only one resource to each activity Code with a “family member” Do not disaggregate project management
Module 7 Session 7.1 Visual 15
Master summary schedule House deliverable
Plan (A)
Site (C)
Foundation (C)
Frame (C)
Roof (SC)
Systems(SC) Plumbing (P) Electrical (E) Telephone (T)
Project mgt (PM)
4 8 12 16 20 24
WEEKS
Prepare
Construct
Construct
Construct
Prepare
Install
Continuous activity
From WBS summary activities or sub-projects or work package
CODE RESP.
10
20
30
40
50
60
70
Module 7 Session 7.1 Visual 16
Summary activity Disaggregate into activities
Terminology: Activity or Task
Module 7 Session 7.1 Visual 17
Summary activity # 10—PLAN Disaggregate into activities
Buy land
Study site
Define requirements
Finalize drawings
Select contractor
Order utilities
Plan construction
Module 7 Session 7.1 Visual 18
Activity list for house projectSummary activity: Planning #10
100
# Activity Responsibility Duration Start Finish(weeks) (weeks)
Buy land Owner 1 0 1
102
Study site Architect 2 1 3
103
104
105
106
Define requirements
Finalize drawings
Select contractor
101
Order utilities
Plan construction
Architect
Architect
Owner
Architect
Contractor
2
2
1
1
1
1 3
3 4
4 6
4 5
6 7
Module 7 Session 7.1 Visual 19
Bar chart for house project Summary activity: Planning #10
100
# Activity Duration(weeks)
Buy land(Owner)
1
102
Study site(Architect)
2
103
104
105
106
Define requirements
Finalize drawings
Select contractor
101
Order utilities
Plan construction
(Architect)
(Architect)
(Owner)
(Architect)
(Contractor)
2
2
1
1
1
1 2 3 4 5 6 7
xxxx
xxxx xxxx
xxxx xxxx
xxxx
xxxx xxxx
xxxx
xxxx
Module 7 Session 7.1 Visual 20
Network diagram family
Critical path method (CPM)
Precedence diagram (PDM)
Time-scaled precedence diagram
Arrow diagram
PERT diagram
Module 7 Session 7.1 Visual 21
Precedence diagram method (PDM)House projectSummary activity: Planning #10
100 1
Buy land
Owner
103 1Finalize drawings
Architect
106 1
Plan construction
Contractor
101 2
Study site
Architect
102 2Define
requirements
Architect
104 2
Select contractor
Owner
105 1
Order utilities
Architect
DurationActivityident. no.
Activitydescription
Resource
Module 7 Session 7.1 Visual 22
Critical Path (thick lines)House projectSummary activity: Planning #10
100 1
Buy land
Owner
103 1Finalize drawings
Architect
106 1
Plan construction
Contractor
101 2
Study site
Architect
102 2Define
requirements
Architect
104 2
Select contractor
Owner
105 1
Order utilities
Architect
DurationActivityident. no.
Activitydescription
Resource
Module 7 Session 7.1 Visual 23
Time-scaled precedence diagramHouse project
Activity Box
103 1Finalize drawings
Architect
101 2
Study site
Architect
102 2
Define requirements
Architect
100 1Buy land
Owner
FenceSlack orfloat
1 2 3 4 5 6 7Time scale in weeks
105 1
Orderutilities
Architect
106 1
Plan construction
Contractor
104 2
Select contractor
Owner
Summary activity: Planning #10
Module 7 Session 7.1 Visual 24
Key concepts
Project duration
Critical path
Float or slack
Module 7 Session 7.1 Visual 25
Mathematical Analysis
Early start (ES)
Late start (LS)
Early finish (EF)
Late finish (LF)
Module 7 Session 7.1 Visual 26
Table printout House projectSummary activity: Planning #10
# Activity ResponsibilityDuration(weeks)
Early start
Early finish
Late Start
Late finish
Total float
100 Buy land Owner 1 0 1 0 1 0
101 Study site Architect 2 1 3 1 3 0
102Define requirements
Architect 2 1 3 1 3 0
103Finalize drawings
Architect 1 3 4 3 4 0
104Select contractor
Owner 2 4 6 4 6 0
105 Order utilities Architect 1 4 5 5 6 1
106 Plan Contractor 1 6 7 6 7 0
Module 7 Session 7.1 Visual 27
Tool comparison
Tool When to use Example
Bar chart
Network diagram
Simple sequentiallogic with few parallelactivities
Complex sequentiallogic with many parallelactivities
Road construction
Bridge constructionWater supply systemconstruction
Module 7 Session 7.1 Visual 28
Making a CPM network:The process
Create activity list form for summary activities
Disaggregate summary activities and complete activity forms
Conduct meeting with managers
Develop logical sequence
Create network diagram
Blackboard version
Computer version
Module 7 Session 7.1 Visual 29
Activity listProject no.________Title: _______________________________ Summary activity No._________Title _______________
Date prepared: ____________________ Responsible person: _______________________________
No. Description Organizationalunit
Individualresponsibility
Manpowernumber
Cost Duration Start Date* Finish date*
* To be filled in after CPM is completed.
Module 7 Session 7.1 Visual 30
Making a PDM network:The mechanics
1. Make activities flow from left to right
2. Have one start box and one finish box
3. Draw arrows as you go
4. Draw arrows to and from end of box and parallel to horizontal
5. Can show any logic
6. Try to avoid crossing lines
7. Leave no hanging activities (danglers)
Module 7 Session 7.1 Visual 31
Simple finish to start
Hire salesmen
1
Train salesmen
3
Sell to distributors
5
Source: Mulvaney, Analysis Bar Charting
Module 7 Session 7.1 Visual 32
Two predecessors
Agree on testspecification
16
Obtain testequipment
18
Test part X
20
Source: Mulvaney, Analysis Bar Charting
Module 7 Session 7.1 Visual 33
Multiple starts after decision
Prepare contractors’ list
23
Start working drawings
25
Arrangeaccess road
27
Prepare engineering
subcontracts
29
Instructarchitects to
proceed (Approval)
21
Source: Mulvaney, Analysis Bar Charting
Module 7 Session 7.1 Visual 34
Cross-relationships
Machine part I
143
Machine part II
145
Obtain rawmaterial
139
Issue jobcards
141
Source: Mulvaney, Analysis Bar Charting
Module 7 Session 7.1 Visual 35
Making a PDM network:The mechanics
1. Make activities flow from left to right
2. Have one start box and one finish box
3. Draw arrows as you go
4. Draw arrows to and from end of box and parallel to horizontal
5. Can show any logic
6. Try to avoid crossing lines
7. Leave no hanging activities (danglers)
Module 7 Session 7.1 Visual 36
Hanging activities
Start Finish
A
B
C
D
E
F
Module 7 Session 7.1 Visual 37
CalculationsSolve for ES, EF, LS, and LF
0 2
LFLS
A2
B4
D1
C2
EFESES ES
ES
EF
EF
EF
LFLS LFLS
LFLS
Module 7 Session 7.1 Visual 38
CalculationsSolve for ES, EF, LS, and LF (continued)
0 2
LFLS
A2
B4
D1
C2
Critical path
2 6
62
6 7
76
2 4
64
0 2
EFES
Don’t take shortcuts.
Module 7 Session 7.1 Visual 39
Mechanics of calculations
Backward pass
0 3
0 3
33 7
3 7
47 9
7 9
2
From rightto left
Write onbottom
Finds criticalpath and float
When a choice is available, take the lowest.
Forward pass From leftto right
Write on top Finds duration
When a choice is available, take the highest.
A B C
Module 7 Session 7.1 Visual 40
Summary
Planning is essential
Tools facilitate planning
Critical path and float are key concepts
Calculating the network is an essential skill
Module 7 Session 7.1 Visual 41
“Sample” network calculations Problem
Start
Finish
0 0 4
A4
C2
D5
B2
E1
(Weeks)
Module 7 Session 7.1 Visual 42
“Sample” network calculations Solution
Start
Finish
0 0 4
A4
C2
D5
B2
E1
(Weeks)
4 6
0 4 4 6
2 3
6 11
6 11
0 2
8 10 10 11
11
11
Criticalpath
Path B - Efloat = 8
Module 7 Session 7.1 Visual 43
B : 2 E 1
A : : : 4 C : 2 : D : : 5
1 2 3 4 5 6 7 8
Start Finish
B and E share path float of 8 (Total)Depending on when B is done E could have less activity float (Free)
0 1 2 3 4 5 6 7 8 9 10 11
“Sample” time-scaled precedence diagram Solution
Module 7 Session 7.1 Visual 44
Two kinds of float or slack
Activity float (Free)
Path float (Total)
Module 7 Session 7.1 Visual 45
Module 7
Planning and Scheduling with the Critical Path Method
Session 7.1Planning Tools: Arrow Diagram and PERT Diagram
Module 7 Session 7.1 Visual 46
Network diagram family
Critical path method (CPM)
Precedence diagram (PDM)
Time-scaled precedence diagram
Arrow diagram
PERT diagram
Planning tools: Arrow diagram and PERT diagram
Module 7 Session 7.1 Visual 47
Restate history
Draw distinctions
Give reasons why precedence diagrams are recommended
Objectives
Module 7 Session 7.1 Visual 48
Arrow Kelly and Walker at Du Pont
How to solve scheduling problems
U.S.A., 1957
Precedence France
PERT Booz-Allen and Hamilton
Polaris Submarine (US Navy)
U.S.A.
History
Module 7 Session 7.1 Visual 49
Arrow diagram networkHouse project
1
2
3
4 5
6
7 8
Define102
Plan103
Select104
Plan construction
106
2 21 1
Permits101
Utilities102
12
Duration in weeksDotted lines are dummy activities.Dummies are zero time dependencies.
Buy land1001
Summary activity: Planning #10
Module 7 Session 7.1 Visual 50
PERT diagram
Completeplans
Landbought
Start0
Event on node 3 time estimates
Shortest 1.5Most likely 3.0Longest 5.0
Expected time 3.08
FormulaFormula
3.08
(1 x shortest) + (4 x most likely) + (1 x longest) = 1.5 + 12 + 5 = 18.56 6 6
Module 7 Session 7.1 Visual 51
Three types of network methods
4 5 Prepare plan3
3
Planprepared
3.08
Activity on arrow Activity on node Event on node
Arrow diagram Precedence diagram (PDM)
Original PERT3 time estimates
Module 7 Session 7.1 Visual 52
Time-scaled precedence diagramHouse project
Activity Box
103 1Finalize drawings
Architect
101 2
Study site
Architect
102 2
Define requirements
Architect
100 1Buy land
Owner
FenceSlack orfloat
1 2 3 4 5 6 7Time scale in weeks
105 1
Orderutilities
Architect
106 1
Plan construction
Contractor
104 2
Select contractor
Owner
Summary activity: Planning #10
Module 7 Session 7.1 Visual 53
Prepare plan : 2W
Time-scaled precedence diagram(merging Arrow and Precedence diagrams)
2WPrepare plan
2W
or
Prepare Plan
Broadened arrow Lengthened box
Time-scaled bar
Node and arrow merge
Module 7 Session 7.1 Visual 54
PERT
Typically not worth the effort
Arrow
Can be complicated to learn
Precedence
Easiest to learn and use
Supported by PC software
Which diagram to use?
Module 7 Session 7.1 Visual 55
Summary: Key ideas
Planning – a process, not an event
Planning tools select – the right one
CPM – a powerful, focusing methodology
Time-scaled precedence diagram – recommended
Module 7 Session 7.1 Visual 56
Summary: Networking process
Create activity form for summary activities
Define objectives, deliverables, and summary activities
Disaggregate summary activities
List activities and responsibilities
Assign responsibility
Estimate duration for each activity
Sequence activities
Calculate the network (Critical path + float)
Module 7 Session 7.1 Visual 57
START
G
A
B
C
D
I
F
E
H
106 4
108 1
105 3
109 1
103 1
101 2
102 2 104 2
107 1
Precedence diagram
0
Activity 7.1.3: ABC, Network Analysis Exercise, Solution 1 of 6
Module 7 Session 7.1 Visual 58
START
C
D
I
F
E
H
106 4
108 1
105 3
109 1
103 1
104 2
Precedence diagram with critical path3 4
G
107 1
0 1
4 5
A
101 2
0 2
1 3
B
102 2
0 2
0 2
02 3
2 3
2 4
4 62 3
5 6
5 6
3 6
3 6
6 10
6 10
Critical path
0
Activity 7.1.3: ABC, Network Analysis Exercise, Solution 2 of 6
Module 7 Session 7.1 Visual 59
Time-scaled precedence diagram
Company: Scale: 4=1 Week Title: ABC, Network Plannning Exercise
Division: Unit of Time: Manager:
Approved: Prepared by: Date:
107 G 1108 H 1
101 A 2
102 B 2103 C 1
105 : E 3
109 I 1
104 D 2
106 : : F 4
1 2 3 4 5 6 7 8 9 10
Weeks
Number:
Activity 7.1.3: ABC, Network Analysis Exercise, Solution 3 of 6
Module 7 Session 7.1 Visual 60
Arrow diagram
1
6
2
3 4
5
7
2-6 Constraint dummy5-4 Procedural dummny
4F
1I
2
D
E3
C1
B2
A2
G1
H1
0
0
Activity 7.1.3: ABC, Network Analysis Exercise, Solution 4 of 6