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: