Skip to content

CivilNotePpt

  • Home
  • CONCRETE
  • Highway
  • Railway
  • WasteWater
  • BMC
    • Building Material
    • Building Construction
  • soil
  • Toggle search form

What is a Dummy Activity? Example, Purpose & Rules

Posted on 28th July 201929th August 2023 By Malay Sautya

What is a Dummy Activity?

  • A dummy activity is an imaginary activity.
  • It is represented by the dashed arrow.
  • Does not consume any time and resources.

Example of Dummy Activity

Dummy Activity

Purpose of Dummy Activity

There are two reasons to use dummy activity one is grammatical purpose another one is logical purpose.

1. Grammatical Purpose

We will try to understand it by seeing the picture. The activity ‘A’  starts from node 1, and B also starts from node 1, and both activities end at node 2.  

Purpose of Dummy Activity: 1. Grammatical Purpose

We can represent it as follows:

  • A ⇒(1,2)
  • B ⇒(1,2)

Now you can see that both identities are the same, so they lose their identity. Here, the main logic is that they both start at the same time and also finish at the same time. To find out their identity with logic, we used a dummy activity as fig.2

Now we can represent like as
A ⇒(1, 3)
B ⇒(1, 2)

2. Logical Purpose

You can not provide the same activity twice in your network diagram.  

Dummy Activity for Logical Purpose

In the above picture, it shows that the P activity is two times in a single network diagram. So to avoid these types of errors in the network diagram, we provide a dummy activity.

Rules for Removing Redundant Dummy Activity

You can use as many dummy as you wish, but sometimes it asks to remove dummy which is not required. Five golden rules are used for removing redundant dummy. 

Rule: 1

If the dummy originated from one node.

Rules 1 for Removing Redundant Dummy Activity

Here, the P1 dummy is not required

Rule: 2

If a dummy is the only arrow going into a node.

Rules 2 for Removing Redundant Dummy Activity

Here, A3 dummy is not required

Rule: 3

If two activities have set of a predecessor.

Rule: 4

If two activities have the same set of a successor.

Rules 4 for Removing Redundant Dummy Activity

Here, A2 and B2 dummy activities are not required

Rule: 5

Do not repeat already implied logic.

Share this:

  • Click to share on Twitter (Opens in new window)
  • Click to share on Facebook (Opens in new window)
  • Click to share on WhatsApp (Opens in new window)
  • Click to share on Reddit (Opens in new window)
  • Click to share on Pinterest (Opens in new window)

Related

Contents

  • 1 What is a Dummy Activity?
  • 2 Example of Dummy Activity
  • 3 Purpose of Dummy Activity
    • 3.1 1. Grammatical Purpose
    • 3.2 2. Logical Purpose
  • 4 Rules for Removing Redundant Dummy Activity
    • 4.1 Rule: 1
    • 4.2 Rule: 2
    • 4.3 Rule: 3
    • 4.4 Rule: 4
    • 4.5 Rule: 5
    • 4.6 Share this:
    • 4.7 Related
PERT & CPM

Post navigation

Previous Post: Dropping Weight Method -To Determine Soil Bearing Capacity
Next Post: Acoustics of Room and Reverberation Time

More Related Articles

What is Crash Cost? PERT & CPM

Categories

  • Highway engineering
  • Railway Engineering
  • BMC
  • WasteWater
  • soil
  • CONCRETE
  • Building Construction
  • Irrigation Engineering
  • Hydraulic Structure
  • water
  • Cement
  • Foundation Engineering
  • Aggregate
  • Mathematical Example
  • Tunnels
  • Survey Engineering
  • PAVEMENT DESIGN
  • Hydrology
  • PAVEMENT DESIGN – MCQ
  • Building Material
  • Floors
  • Highway Engineering – MCQ
  • HYDROLOGY M.C.Q
  • Engineering Geology – M.C.Q
  • Railway Engineering – MCQ
  • Water Supply – MCQ
  • Building Materials – MCQ
  • Soil Engineering – MCQ
  • Irrigation Engineering – MCQ

Popular Posts

  • The 75+ Best Online Furniture Stores for 2023
  • 10 Types of Roads Classification in India(Urban & Non-Urban Road)
  • 3 Characteristics of Sewage – Physical, Chemical and Biological Characteristics
  • TYPES OF RAILS – Double Headed, Bull Headed and Flat Footed Rails
  • 6 Types of Classification of Gradient – Ruling, Limiting, Exceptional, Minimum, Average and Floating Gradient
  • Railway Gauge – || Definition || Types || Factor Affecting || Advantages of Uniform Gauge ||
  • 8 Different Types of Cement Tests || Laboratory & Field Test
  • History of Road Development in India
  • 100+ All Traffic Signs or Road Safety Signs in India as per IRC
  • Home
  • About Us
  • Contact
  • Privacy Policy for civilnoteppt

Copyright © 2023 CivilNotePpt.

Powered by PressBook Blog WordPress theme