Basics in Building Construction

Basics in Building Construction 4(2+2)

Lesson 31 and 32 : Construction Project Management

Rules To Be Followed While Drawing A Network

Important rules to be observed in drawing a network are as under

1. Each activity is represented by one and only one arrow.





2. An event cannot occur until all activities leading to it completed. In accordance with this rule, event no. 3 cannot occur until activities 1-3 and 2-3 are completed.
3. No activity can start until its preceding events have occurred.
4. Every activity of the network should be completed to achieve the overall completion of the project.
5. An event cannot occur twice. This means there can be no network path looping back to a previously accomplished event.
6. This rule is explained with the help of figure above. In the above figure activity no 5-3 is forming a loop and hence the network is incorrect. This is on account of the fact, that if we want to interpret such a diagram , we will have to say that event -5 can occur only after events 2-3 and 4 have occurred therefore looping back event-3 which has already occurred is not possible as it is not a logical sequence. Thus no event can depend for its completion upon the completion of a succeeding events.





7. In the network, time is assumed to flow from left to right.
8. Length of the arrow is chosen to suit drafting convenience. It has no other significance.
9. Network has to be a closed diagram.





10. In this figure event no. 4 is shown unconnected. This situation is not permissible in a network. Event no. 4 has to be connected to some other event depending upon inter-relationship.
11. All constraints and inter-dependencies must be shown in the network.