Project Management: A Managerial Approach

Chapter 8

Scheduling

Overview

• WBS to Schedule Process

• PERT

• Schedule Types

• CPM

Scheduling

• A schedule is the conversion of a project action plan into an operating timetable

• It serves as the basis for monitoring and controlling project activity

• Taken together with the plan and budget, it is probably the major tool for the management of projects

Scheduling

• In a project environment, the scheduling function is more important than it would be in an ongoing operation

• Projects lack the continuity of day-to-day operations and often present much more complex problems of coordination

Chapter 8-2

Scheduling

• The basic approach of all scheduling techniques is to form a network of activity and event relationships

• This network should graphically portray the sequential relations between the tasks in a project

• Tasks that must precede or follow other tasks are then clearly identified in time as well as function

Chapter 8-3

Types of Scheduling

• Operation Scheduling: a type of scheduling that assigns jobs to machines or workers to job. Operation schedule is crucial because many performance measures such as on-time delivery, inventory levels, the manufacturing cycle time, cost and quality, relate directly to the scheduling of each production lot.

• Workforce Scheduling: a type of scheduling that determine when employee work. Workforce scheduling is equally crucial because measures of performance such as customer waiting time, waiting-line length, utilization, cost, and quality related to the availability of the servers

Chapter 8-2

Techniques of Scheduling

• Gantt Chart

• Network Techniques: PERT & CPMBoth of the techniques is called diagramed technique of

scheduling which possesses the following benefits:

– It is a consistent framework for planning, scheduling, monitoring, and controlling the project

– It illustrates the interdependence of all tasks, work packages, and work elements

Chapter 8-2

Scheduling• Network benefits (cont.):

– It aids in ensuring that the proper communications take place between departments and functions

– It determines an expected project completion date

– It identifies so-called critical activities that, if delayed, will delay the project completion time

– It identifies activities with slack that can be delayed for specific periods without penalty

Chapter 8-5

Scheduling

• Network benefits (cont.):– It determines the dates on which tasks may be

started or must be started if the project is to stay on schedule

– It illustrates which tasks must be coordinated to avoid resource timing conflicts

– It illustrates which tasks may run, or must be run, in parallel to achieve the predetermined project completion date

– It relieves some interpersonal conflict by clearly showing task dependencies

Chapter 8-6

Gantt chart

Advantages

-Gantt charts are quite commonly used. They provide an easy graphical representation of when activities (might) take place.

-Simple& quickest method.

Limitations

- Do not clearly indicate details regarding the progress of activities

- Do not give a clear indication of interrelation ship between the separate activities

Simple Schedule – Gantt Chart

Network Techniques: PERT and CPM

• With the exception of Gantt charts, the most common approach to scheduling is the use of network techniques such as PERT and CPM

• The Program Evaluation and Review Technique (PERT) was developed by the U.S. Navy in 1958

• The Critical Path Method (CPM) was developed by DuPont, Inc during the same time period

Chapter 8-7

Network Techniques: PERT and CPM

• PERT has been primarily used for research and development projects

• CPM was designed for construction projects and has been generally embraced by the construction industry

• The two methods are quite similar and are often combined for educational presentation

Chapter 8-8

Scheduling Terminology

• Activity - A specific task or set of tasks that are required by the project, use up resources, and take time to complete

• Event - The result of completing one or more activities. An identifiable end state occurring at a particular time. Events use no resources.

• Network - The combination of all activities and events define the project and the activity precedence relationships

Scheduling Terminology

• Path - The series of connected activities (or intermediate events) between any two events in a network

• Critical - Activities, events, or paths which, if delayed, will delay the completion of the project. A project’s critical path is understood to mean that sequence of critical activities that connect the project’s start event to its finish event

Chapter 8-10

Scheduling Terminology

• An activity can be in any of these conditions:– It may have a successor(s) but no predecessor(s) -

starts a network

– It may have a predecessor(s) but no successor(s) - ends a network

– It may have both predecessor(s) and successor(s) - in the middle of a network

Steps in CPM Scheduling

• 1. Specify the individual activities.

• 2. Determine the sequence of those activities.

• 3. Draw a network diagram.

• 4. Estimate the completion time for each activity.

• 5. Identify the critical path (longest path through the network)

• 6. Update the CPM diagram as the project progresses.

Drawing Networks

• Activity-on-Arrow (AOA) networks use arrows to represent activities while nodes stand for events

• Activity-on-Node (AON) networks use nodes to represent activities with arrows to show precedence relationships

• The choice between AOA and AON representation is largely a matter of personal preference

Chapter 8-12

The Project Network

• Use of nodes and arrows

Arrows An arrow leads from tail to head directionally– Indicate ACTIVITY, a time consuming effort

that is required to perform a part of the work.

Nodes A node is represented by a circle

- Indicate EVENT, a point in time where one or more activities start and/or finish.

Activity on Node & Activity on Arrow

Activity on Node

- A completion of an activity is represented by a node

Activity on Arrow

- An arrow represents a task, while a node is the completion of a task

- Arrows represent order of events

Activity Code

Activity Duration in days Depends on

A Prepare Technical Specifications 10 -----

B Tender Processing 25 A

C Release of work order 3 B

D Supply of Boiler equipment 60 C

E Supply of Auxiliaries 20 C

F Supply of pipes & pipe fittings 10 C

G Civil Work 15 C

H Installation of Auxiliary equipment & piping

5 E,F&G

I Installation of Boiler 10 D&H

J Testing and commissioning 2 I

Requirements: 1. Draw a network diagram

2. Find out the critical Path.

Hypothetical Network

G

B

H

IA

D

6

Start CE

F

J End10 25 3

60

20

10

15 5

5

5

10

2

End of the Lesson