Basic Networks - Construction Project Scheduling and Control - page 31

In larger projects, dummy activities may not only increase the number of activities
but also complicate the schedule. This fact is one of the main disadvantages of arrow
networks. The following example demonstrates this disadvantage.

Example 3.7

Draw the arrow network for the project given next.

Activity IPA Activity IPA

A - H C, D

B A I D

C A J E, F, G

D A K F,G,H

E B L H, I

F B,C M K,L

G C

Solution

This example is more complicated than the previous ones, requiring eight
dummies, as shown in Figure 3.7. However, real projects with hundreds or
thousands of activities, are far more complicated.

Figure 3.7 Solution for example 3.7

Redundancies

It is interesting to note that when you are building an arrow network, you can have
not only a logically improper network but also a proper one with redundant dummy
activities. This fact is especially true for complicated networks. Redundant dummy