## Simple Network

Figure 3-4 illustrates a simple network of an arrow diagram. There are three activities: A, B and C. They can be defined as follows: A is the beginning activity; B follows A but cannot begin until A is complete; and C is the final activity following the completion of B. As shown, there is a logical sequence of work starting from left to right.

Project Management for Engineering and Construction Figure 3-3. CPM Drawing Methods

ARROW DIAGRAM

TIME SCALED DIAGRAM

PRECEDENCE DIAGRAM

 C E G 4 1 2 1 1 [ D F H 3 I 5 ¡ i I 1 2 3 4 5 6 7 8 910 1112131415

Figure 3-4. Simple Network

NODE

NODE

NODE

NODE

NODE

ACTIVITY

START A

ACTIVITY

NODE

ACTIVITY

FINISH A

START B

ACTIVITY

NODE

ACTIVITY

FINISH B

START C

ACTIVITY

NODE

FINISH C

START A

FINISH A

START B

FINISH B

START C

FINISH C

> LOGICAL SEQUENCE CR PLAN CF WORK

Problem 3-1 : Network Development

In order to develop a network, the following example illustrates the steps involved. Given the data as indicated in Figure 3-5, draw an appropriate network.

Activities must follow in a logical sequence.

Analysis

First, read through the given data and note that this in a nine-activity network. Activity A is the first activity and Activity I is the last.

Figure 3-5. Network Development Problem Given:

1) Activity E3 follows activity

2) Activity A is the beginning activity

3) Activity C follows activity A

4) Activity C precedes activities E & F

5) Activity p follows activity B

6) Activity G follows activities D & £

7) Activity F precedes activity H

8) Activities G and H precede activityJ_

9) Activity _[_is the last activity Draw the appropriate network.

Figure 3-6 shows the completed network diagram. Networks become more complex as activities are added and durations are established for each activity. Activity durations can be in days, weeks, or months; therefore, it is essential to determine from the outset the time scale. Logical sequence and durations for each activity can be determined by past experience or by work content in relation to available resources. This determination should evolve from consultation between the scheduler and appropriate construction and engineering personnel. It is important that an operating group concur with the schedule development, accept it as their schedule, and make a commitment to operate as per the plan and schedule. Work sequence can then be checked and durations assigned to each activity.

Figure 3-6. Network Development Solution SOLUTION

Figure 3-6. Network Development Solution SOLUTION  