Activity for example there are no immediate

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activity. For example, there are no immediate predecessors of activities A, B, and C.This means that these activities can be done as soon as the project starts. Activity A isthe immediate predecessor of activity D, so activity D can be done only after activityA has been completed. Activities E and F can be done only after activity B (immedi-ate predecessor of E and F) has been completed. Activity G must be done after activ-ity C has been done. Activity H requires that activities D and E are completed beforeone can start on activity H. Similarly F, G, and H need to completed before activityI can start and finally activity I needs to be completed before activity J can start.The relationships among activities can also be given by specifying the immediatefollower(s). For example, D is an immediate follower of A. It is the same thing assaying that A is the immediate predecessor of D. Activities E and F are the immedi-ate followers of B. Activity G is the immediate follower of C; activity H is the imme-diate follower of D and E; activity I is the immediate follower of F, G, and H; and Jis the immediate follower of I. Activity J has no immediate follower since J is the lastactivity of the project. In any project, it is sufficient to specify either the immediatefollowers or the immediate predecessors.Table 7.1 Project DataActivityImmediate PredecessorsImmediate FollowersTime (Weeks)ANoneD9BNoneE, F5CNoneG7DAH12EBH8FBI6GCI11HD,EI5IF,G,HJ4JINone10Note:Either immediate predecessors or immediate followers need to be specified.K14666_C007.indd24811/16/201311:01:27 AM
Project Management249The relationships given in Table 7.1 and discussed above are shown in Figure7.1. Each activity is represented in a circle. The arrows show the relationships. Byconvention, the “Start” and “End” activities are added to make a single beginningand a single ending of the project. The times for the Start and End activities will bezero. This diagram is called an Activity on Node (AON) diagram because circles arethe nodes and each activity is represented as a node. This diagram is also known asa network or network diagram.7.7 Critical Path and Project DurationCritical path is defined in terms of time. PERT/CPM is a time-based method.Time and cost estimates will be related at a later point. For now, time is the crucialparameter. The goal is to determine the project duration with the aim in mind toachieve the shortest project completion time and then, control of project-cycle timeto meet the goals of the plan.The project duration can be found by listing all the paths in the network. Thisproject network shown in Figure 7.1 has four paths. These are listed in Figure 7.2.The Start and End activities are not included while listing the paths. The length ofPathsLengthADHIJ40Critical PathBEHIJ32BFIJ25CGIJ32Figure 7.2 Path-length (weeks).

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Term
Fall
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GEORGEKYPARISIS

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