Dependencies and Network Diagram
The network diagram is a schematic representation showing the sequence and relationship/ dependency of the tasks along with their duration. All the tasks, except the first and the last, are linked with at least one predecessor and successor to have a proper sequence of work. This logical dependency between the tasks will determine afterwards the duration of the project. There are four types of dependencies which define the relation between pair tasks Finish-to-start (FS- the second task ‘successor’ can’t begin until the first ’predecessor’ is completed), Finish-to-finish (FF- the completion of the successor depends on the completion of its predecessor), Start-to-start (SS- the start of the successor depends on the start of its predecessor), Start-to-finish (SF- the finish of the successor depends on the start of its predecessor).
However the duration of the project is meaningless without identifying what is driving the project, why the project takes so long, what possible action is required to shorten the duration or what possible risk may extend the project... Among the set of activities interconnected on the diagram; there is always one longest duration path from start to end of the project travelling through the network, Carmichael D. (2006, p.51). This longest path is also known as a critical path driving the project duration and all tasks falling on this path are called critical activities. Any delay which occurs on these critical activities will delay the project completion time as well. The critical path analysis is carried out in three steps. The first step consists of forward pass which calculates the early schedule (earliest start time and earliest finish time of a task). If a schedule activity has two or more predecessors, its early start is governed by the early finish time of the preceding activities whichever is maximum. The second step is the backward pass which calculates the late schedule...
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