The schedule of a project is developed when the project action plan is transformed into a workable timetable. This timetable indicates the beginning and completion dates of all tasks, how the tasks correlate with each other, and which team members and resources are required for delivery. Even though schedules are planning and control tools, it is variable and should be updated as the project progresses (AIPM, 2021).
A rudimentary scheduling technique is to create a network of activity, by putting together a Network Diagram. A network diagram, similar to the one below should be drawn up.
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A network diagram is a visual, which depicts the tasks and events of a project. In this visual, sequenced activities, how tasks relate to one another, performing some tasks first and others last are all clearly laid out (ACQ Notes, 2021).
There are two types of networking techniques, these are:
Program Evaluation and Review Technique (PERT)
Critical Path Method (CPM)
There are many terms used in scheduling, below are five, along with a brief definition for each one:
Activity - tasks that must be completed during a project. Tasks consume time and resources. Activities may have a successor (starts a network), a predecessor (ends a network) or it may have a predecessor and a successor
Event - the date that a task was completed
Network - the amalgamation of all activities and events
Path - the connectivity between two events
Critical - the series of activities from start to finish that is required for a project to be completed. Should any of these activities be delayed, then it will result in the project being completed later than anticipated
There are two types of network diagrams:
1.) Activity-on-Arrow (AOA)
An AOA network illustrates activities as a line between two circles. The start of the event is represented by the first circle, and the end of an event is represented by a second circle. The broken lines in an AOA network are called Dummies and these lines represent a dependance between two events. These lines must not be confused with activities (Praxis, 2019). The image below depicts an AOA network diagram:
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2.) Activity-on Node (AON)
An AON network illustrates activities as boxes. At the start, a box will connect with arrows to another box (node) and then on to another box. The resultant visual is that of logical progression of the dependancies between activities (Davis, 2021). The image below illustrates an AON network:
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The longest sequence of activities in a network diagram is called a critical path. This string of activities must be completed on time. If any of the activities on the critical path are delayed, it will result in a delay of the project.
Float is the term used to describe the amount of time that an activity can be delayed. Activities that have scope are not on the critical path (Kulakov, 2020).
There are six steps to drawing a critical path on a network diagram:
Specify each activity
Establish activity sequence
Draw the network diagram
Estimate how long it will take to complete each activity
Figure out the longest sequence of activities, i.e; the Critical Path
Revise the Critical Path Diagram to indicate progress that has been made (Davis, 2021)
In the image below the Critical Path is portrayed by the red line.
©acqnotes.com
In the video below, Dr. Mustafa Canbolat takes us through how to draw an AON diagram and how to identify the critical path:
A forward pass is a process that is used to navigate a project network diagram. It helps calculate the early start, duration and early finish values of an activity (Wrike, 2021). The forward pass is calculated from left to right.
The video below helps simplify the process:
Now that the Critical Path has been determined, using the forward pass, the backward pass is used to determine the float on all other activities, i.e: those activities that if delayed will not delay the project in it’s entirety.
The backward pass is calculated from right to left, and is used to determine the latest start time and latest finish time for activities.
In the video below, backward pass is determined:
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