QS Study

Critical Path Determination in the Project Networking

A critical path is an activity or event that, if delayed, will delay project completion. It is the chain of stages formative the least time needed for an operation, particularly when analyzed on a computer for a big organization. The necessary method for using critical path management is to assemble a model of the project that includes the following:

  • A list of all activities required to complete the project,
  • The dependencies between the activities, and
  • The estimate of time (duration) that each activity will take to completion.

Critical path determined: Once the network diagram with single time estimates has been developed, the following computational procedure may be employed for determining the critical path/s, event slacks. And activity floats.

Calculate the Earliest Occurrence Time (EOT) for each event: An event occurs when all activities leading to the event have been completed.

Calculate the Latest Occurrence Time (LOT) for each event: The LOT for an event represents the latest allowable time by which the event can occur, given the time that is allowed for the completion of the project (occurrence of end event). Normally, the time allowed for the completion of the project is set equal to the EOT of the end event.

Calculate the slack for each event: The slack for an event is the difference between its LOT and EOT.

Obtain the critical and slack paths: The critical path starts with the beginning event, terminates with the end event, and is marked by events which have a zero slack. This is obviously the path on which there is no slack, no cushion. Other paths are slack paths with some cushion.

Compute the activity floats: Given the estimates of activity time and event slacks, activity floats can be calculated. There are three measures of floats. These are

(i) Total float;

(ii) Free float; and

(iii) Independent float.

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