The CPM network is drawn with the help of the above mentioned principles. It is better if one avoids the numbering of the events or nodes in the first attempt to develop the network. Different activities are best identified either by an alphabetical code or better still by a numerical code which can be easily derived from the detailed Work Breakdown and activity listing. After the first trial of the network drawing is done, it is better to go back once again to the technical experts and to the top executives managing this project to verify the accuracy or validity of the different sequencing relationships between the different jobs. Quite often during this verification procedure, some important technological factors earlier omitted come to light. For instance in a state level dairy development project, after drawing the network it was found that in the animal husbandry portion of the project an important activity had been missed. The activity of importing stud bulls from abroad had been considered; but it was forgotten that the stud bulls imported from the colder countries in the West needed ‘acclimatization’ to the Indian condition for as long a period as 6 months before they could be ‘serviced’. This made a significant difference to the schedule of the project. It may be noted that only after a few trials and reverification of the ‘sequencing logic’ or the inter-relationships of the activities does the final form of the network emerge.
Numbering of the Events or Nodes:
After this stage, one can number the different events in a systematic manner with numbers increasing from left to right and from top to bottom. Since the flow of certain dummies may be either vertically downwards or vertically upwards, depending upon the flow of the dummies one may number the succeeding events. Although such a numbering system helps in identifying the different activities easily, if one were to carry out further analysis on a computer, such a convention would not be absolutely necessary. What one should have is an independent identification for each individual activity in terms of the start and end notes (events).
Use of Aggregated Networks and Part Networks:
For a large project, such as a hydel for instance, the number of activities may run into thousands. Naturally, the complete CPM charts would be quite complicated. Although such a detailed network is definitely necessary and useful, not all the executives in the different hierarchical levels in an organization will be interested in all the jobs indicated on such a network. The top level management may be interested in only a grosser sub division of the work and not in too many detailed activities. Certain functional departmental heads will be interested in only activities related to the work of their departments and not in the complete CPM chart for the whole project. Because of these considerations, it is necessary that besides the Master Network there should be various other smaller versions of the CPM chart showing only limited portions of the network. Networks have to be presented to different executives according to their need for planning and their authority and responsibility for the components of work handled by them in the project. Wherever necessary the relationship of their components of the job with the other jobs on other departments will also be indicated in the networks which will be sent to them.
Other tips for Drawing Networks:
For more clarity, while drawing the network one should avoid the crossing of activity arrows. Also, it is better to have a minimum number of dummies. It may also add to our understanding of the network if the network is ‘stratified’ i.e. if different activities are shown against the major Work Breakdown Structure to which they belong.
Once the network has been developed, the corresponding time, cost and other resources requirement figures need to be put on the different activities of the network, for the purposes of an analysis of the network. The purpose of the network is to provide a plan or a guideline for the implementation of the project and therefore, an analysis of the various resources required in light of their constraints if any, and also of the time required to complete the various phases of the project is extremely important.