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Planning and Deterministic scheduling
Motivation for Scheduling
• Reducing chances of delay• Recovering from Delay• Delays result from poor planning• Assigning responsibilities
Motivation for Scheduling
• Better utilization of resources• Identification of critical resources• Identify and Resolution of conflict ahead of time
Motivations for scheduling
• Formalization necessary but not sufficient for managing
Ubiquitous role of scheduling
Importance of schedule • Design (preliminary schedule)
• Establish finish, milestone times for choreographing activities Procurement time, subcontractor presence, tenant occupancy
• Importance for thinking through issues
• Identify critical path
Ubiquitous role of scheduling
Importance of schedule • Communication tool between parties
• Framework for monitoring
• Role in control - Assessing impacts of changes - Allows demonstration of indirect costs - Legal importance
Ubiquitous role of scheduling
Importance of schedule
• Link to resources - Payments - Resource usage
• Identify exposure to external forces (crowding, weather conditions )
Linkage to estimation
• Scheduling allows understanding of cash flow over time
• Given time value of money, scheduling critical to understanding present value of estimate
THE GANTT CHART
•Attributed to Henry Gantt – most popular PM tool (80%)
•Used to plan big shipbuilding projects (cargo ships WWI)
•Graphical way of showing task durations, project schedule
•Does not explicitly show relationships between tasks
•Limited use for project tracking•Easy to understand
A Gantt Chart of a Sample Project
Completion Today Calendar
Gantt: Sequential vs. phased
Hierarchy of Gantt Charts
CPM NETWORKS
History
• Late 1950s– Program Evaluation and Review Technique (PERT)
• U.S. Navy, Booz-Allen Hamilton, and Lockeheed Aircraft• Probabilistic activity durations
– Critical Path Method (CPM)• Dupont De Nemours Inc.• Deterministic activity durations
Gantt vs. CPM
The Language of PERT/CPM
• Activity– task or set of tasks– Have definable ending and beginning– use resources
• Event– state resulting from completion of one or more activities– consume no resources or time– predecessor activities must be completed
The Language of PERT/CPM continued
• Milestones– events that mark significant progress
• Network– diagram of nodes and arcs– used to illustrate technological relationships
• Path– series of connected activities between two events
The Language of PERT/CPM continued
• Dummy activity– An arrow representing merely a dependency of one activity
upon another.– It carries a zero time estimate
The Language of PERT/CPM concluded
• Critical Path– set of activities on a path that if delayed will delay completion
of project
• Critical Time– time required to complete all activities on the critical path
Building the Network
• AOA Network• AON Network
Sample Set of Project Activities and Precedences
Task Predecessor
a --
b --
c a
d b
e b
f c, d
g e
Stage 1 of a Sample AON Network
Stage 2 of a Sample AON Network
A Completed Sample AON Network
Stage 1 of a Sample AOA Network
Stage 2 of a Sample AOA Network
A Completed Sample AOA Network
A Completed Sample AOA Network Showing the Use of a Dummy Task
A Sample Problem for Finding the Critical Path and Critical Time
Activity Predecessor Duration
a -- 5 days
b -- 4
c a 3
d a 4
e a 6
f b, c 4
g d 5
h d, e 6
i f 6
j g, h 4
Stage 1 of a Sample Network
A Complete Network
Information Contents in an AON Node
The Critical Path and Time for Sample Project
Calculating Activity Slack
• Slack or FloatLST - EST = LFT - EFT = Slack
An MSP Version of PERT/CPM Network
A Gantt Chart of Sample Project Showing Critical Path, Path Connections, Slack, EST, LST, EFT, and LFT
A Gantt Chart of a Day Care Project Showing Expected Durations, Critical Path, Milestone, and Resource Requirements
A Progress Report on a Day Care Project Showing Actual Progress Versus Baseline
Exercise 1
Draw a AOA and AON diagrams for the project:
Task Prereq. Time A None 5 B None 6 C None 10 D A 3 E B 4
Exercise 2
Task Prereq. Time A None 4 B None 6 C None 3 D A, B 7 E B, C 8
Draw a AOA and AON diagrams for the project:
Exercise 3
Task Prereq.A NoneB NoneC NoneD AE A, BF A, B, C
Draw a AOA and AON diagrams for the project:
Exercise 4
Task Prereq.A NoneB NoneC AD BE A, B
Draw a AOA and AON diagrams for the project:
Exercise 5
Task Prereq. Time A None 4 B None 9 C None 5 D A, B 6 E B, C 4 F A, B, C 10
(Tricky!)
Draw a AOA and AON diagrams for the project:
Exercise 6
Task Prereq. Time A None 6 B None 4 C None 7 D A 5 E A 9 F C 2 G C 8 H B, E, F 4 I B, D, E, F 7 J B, E, F, G 3
Draw a AOA and AON diagrams for the project: