Figure 9-15. - Multiple predecessors and successors (direct linking).

Figure 9-16. - Multiple predecessors and successors (using dummy collector).

connectors going to a common point to reduce congestion in the drawing. This practice is, however, discouraged.

The diagrams in figures 9-17 and 9-18 have precisely the same interpretation. The danger with

Figure 9-18. - Indirect linking of dependencies.

the form of representation is evident in figure 9-18, where several connectors have been joined. When the network is coded for the computer, you may lose sight of the fact that Activity D has three preceding activities since only one line actually enters Activity D.

PRECEDENCE DIAGRAMS

Scheduling involves putting the network on a working timetable. Information relating to each activity is contained within an activity box, as shown in figure 9-19.

Forward and Backward Pass Calculations

To place the network on a timetable, you must make time and duration computations for the entire project. These computations establish the critical path and provide the start and finish dates for each activity.

Each activity in the network can be associated with four time values:

Early start (ES) - Earliest time an activity may be started;

Figure 9-17. - Direct representation of dependencies.

Figure 9-19. - Information for a precedence activity.