Project Network Analysis With Critical Path Method

  • Post last modified:28 July 2022
  • Reading time:19 mins read

For large businesses or manufacturing organisations, projects are divided into various stages or milestones. For example, a construction company is given a project of construction of a house. This project will have stages like site preparation, putting slabs on the floor, framing of roof, final finishing etc.

To complete the projects, various activities are performed at every stage like deputation of personnel for developing plan for each stage and dividing it into number of activities and assign timelines, forecasting the requirement of workers matching skills required in each stage, assigning roles and responsibilities to employees, conducting inspection for quality check.

In this article, we will discuss the techniques for undertaking these activities and making the project successful in each time. You will gain insights into project scheduling and network analysis using project network analysis methods like the Critical Path Method.


Project Scheduling

Project Scheduling is a process of arranging the sequence of project activities or tasks in a logical manner so that they conclude within the specified time frame, budget and quality. As explained earlier, a project goes through various stages which involve a listing of tasks to be completed in different stages, deliverables and milestones to be accomplished in a project in each period.

Therefore, project scheduling is essential to deliver a project timely as it helps to align the resources, timeline and scope. Project managers can use a variety of scheduling techniques to develop, monitor and control project schedules. The key elements of a schedule are:

  • The start and finish date (as per the plan or blueprint of the project)

  • Duration of the project (divided in the duration of completion of each stage of the project)

  • Resources assigned to each activity of the stages of the project

Project scheduling refers to the process of establishing sequential arrangement of project activities and tasks within the scope of time and allocating resources for different activities. It provides an idea on what has been done when, what are the next upcoming activities and timelines of different project activities.

A project schedule is a tool used to set sequence and timeframes for project activities. The success and timely completion of the project depends upon the effective project scheduling by the team management. Project scheduling saves time, cost and reduces wastage of resources.


Steps of Effective Project Scheduling

Effective project scheduling comprises the following steps:

Preparing the plan schedule

Firstly, the plan or blueprint of the entire project is prepared by the team of senior officials as appointed by the top-level management for undertaking the project. This plan includes budget, the timeline for each stage, activities in each stage, number of employees and workers required in the project, description of roles for each position, internal communication and reporting strategy.

In this stage, all these activities are identified on the project level which gets specified for each stage of the project in the next steps of project scheduling.

Define project activities

In this step, project activities are identified stage wise. The requirement of number of workers, timeline for each activity in each stage is identified and cost analysis for each activity is performed. The roles and responsibilities for employees and workers are defined for each activity in this step of project scheduling.

Sequence activities

Once the activities to be undertaken at each stage of the project are identified; the correct sequence of activities is finalised to save time and cost. This is to ensure there is no redundancy of tasks.

Estimate resources

The final estimate of the number of workers and cost estimate is taken from each department for each activity to be undertaken in each stage of the project to prepare the final budget.

Estimate durations

The final duration to cover each activity in each stage of the project is estimated to convey the final duration for the completion of the project to the client.

Develop the project schedule

The most efficient schedule for project is developed at this stage. The official start and end date is decided for each task. It can be used to direct subcontractors to when to schedule the work, order equipment, and to prioritize internal resources.

It can be said that the project schedule is a collective document of all the activities to be covered in each stage of the project and the time required to cover the activities. Some of the popular tools for project scheduling are GANTT chart and spreadsheets for scheduling of tasks, resources and team management.

The Gantt chart consists of two axes, vertical axis and horizontal axis. The vertical axis represents all the activities in the project. The time scale is represented by the horizontal axis. It is expressed either in absolute time or in relative time with respect to the initial event of the project. Months and weeks are most commonly used units of time.

The beginning and ending of the activities are represented by rows of bars in the chart. The bars overlap, in case, when multiple activities are performed in parallel with one another or activity starts before the completion of another activity. The present point of time can be represented by drawing a vertical straight line on the chart. The status of each activity can be communicated by shading the bars with different colour codes.

The Gantt chart is a useful tool for planning, scheduling and managing a project. It also helps in monitoring and controlling the progress of the project at any point of time.

Project scheduling states project deliverables, realistic timelines with intended start and finish dates and estimation of resources required to execute the project. It takes care of any deviation and assures optimum utilisation of resources. It aids in project planning, project monitoring and control.


Developing a Project Network

A project network is developed to help the management in meeting project timelines and completing the project in time. The project network can be developed in the following steps:

  • The first and foremost task in the development of a network is project planning wherein preparation of quantity requirement, mapping, drawing and specifications for structure or raw material depending upon the type of project is described. In this step, tenders are floated for enquires to purchase raw material, negotiation of tender takes place and a purchase order is issued.

  • In this step, identified number of activities to be performed under the project are arranged in sequence of operation process. The activities are integrated and interdependent. The start point of activities is identified. For example, ideally, the construction of stairs cannot take place till the walls of the building are constructed. However, to make the project economical, these two activities can run alongside. It will help in completing the project quickly.

  • In Figure below of the project network, you will see an arrow connecting one activity with another. The arrowhead is the ‘head’ and the end of the arrow is the ‘tail’. For example, activity ‘A’ is heading towards activity ‘B’; therefore, activity ‘B’ is the ‘head event’ and activity ‘A’ is the ‘tail event’. This process continues till we reach the ‘End’ of the project schedule.

The activity is represented in ‘circle,’ as you can see in the figure above all activities are represented in circle. The length of arrows represents the duration of completion of activities.

In this step, the logical arrangement of activities takes place along with the expression of their interrelationship and schedule. A number is assigned to each event. The head event will have a greater number than the tail event. Let us understand this with the help of a sample of network diagram shown in Figure 10.3.

As you can see, in Figure 10.2, two activities can run simultaneously to save the cost of the project. It should be noted that the arrow of one activity should not come back again to the same activity; in that case, it will form a loop. All the arrows should proceed in the direction ‘left to right’ and not ‘right to left’. If the arrow goes from the right to left direction, it will form a loop which should be avoided. An uncompleted activity should be avoided.

If there are more activities emerging from an event, then such activities can be shown by different arrows arising one in horizontal line above and one in horizontal line below the event. A rough sketch of the network diagram must be constructed before preparing the final version to avoid confusion or problems in construction of the network diagram.


Estimation of Time

Time is a crucial element in project management. All organisations are interested in estimating the time of completion of project before signing the agreement. The accurate estimation of completion of project date is beneficial for both parties. If the estimated time is not derived, one cannot find the duration of the project and cannot commit to other parties about the completion of the project.

If the project is not delivered in time and within the estimated budget, it will fail its purpose and the organisation undertaking the project will earn a bad reputation. Sometimes, a little delay in project deliv- ery may be acceptable but the project manager should possess strong negotiation skills to get the deadlines extended.

The estimation of time must be done by following these steps:

Understand the requirement

The first step in the estimation of time of the completion of the project is to identify the various tasks and activities to be undertaken in the project. Some of the popular tools to identify these activities are business requirement analysis, work breakdown structures, gap analysis and drill-down.

These tools help in the detailed analysis of activities to be covered in the project. A delay in a project may also happen because of the internal management process such as testing, meetings, and reporting to top management. Time for such activities should also be taken into consideration while estimating the time for completion of the project.

Assigning order to the activities

Once the activities to be undertaken in the project have been identified, the project manager proceeds towards the next step of arranging the activities in a logical order. The primary aim of this step is to assign the deadlines for the completion of each activity.

Build a team

In this step, a team is built to complete a project. The roles and responsibilities are assigned to everyone involved in the project.

Final estimates

Till the project manager reaches this step, she has already derived rough estimate of time to be taken for the completion of the project. A project manager should however keep in mind that this estimation of time is more dependent on the completion of activities rather than the completion of the project. The base for completion of the project is the completion of these activities.


Network Analysis

The technique of network analysis is of immense use in the process of planning and controlling of critical and complex projects. In this technique, a system is developed to plan the project outline by analysing the integrated activities to be covered under the project. It gives an idea to the project manager about which activity to complete first and which one later.

A network diagram represents the activities to be performed in the project by presenting a visual representation of activities involved in the completion of the project. The integration of various activities and the cost to be incurred on each activity is represented by this diagram. The top-level management can take effective and quick decisions related to the project at any stage by referring to this network diagram of the project.

The main concern of the top-level management is timely completion of the project with maximum utilisation of resources and minimum wastage. This objective can easily be achieved by controlling the project using network analysis.

Some of the areas where network analysis can be used are:

  • Research and development process undertaken at the organisation for the launch of new product or service.

  • Marketing campaign project of the organisation can use network analysis.

  • Network analysis can be used in planning of inventory and inventory control.

  • Production planning such as assembly line scheduling.

  • Installing or shifting of plant or machinery process can use network analysis.

  • Traffic control for smooth functioning.

  • Budgeting exercises and audit procedures can be effectively conducted through network analysis.

  • Staffing activities in large organisations especially production-based businesses.

Meaning of a Network

A network is a connection of activities or tasks to build a structure. For example, construction of walls, laying the floor, construction of ceiling are all activities that are interconnected to build a structure, say a house or a building.

A network supports the project manager in assigning the activities of the project in logical manner by developing a project network. This helps the manager in taking quicker and timely decisions arranging resources for the activities.

A network not only supports the logical sequence of activities but helps in maximum utilisation of resources with minimum wastage. All concerned parties involved in the project are interested in knowing the timeline for the completion of the project. Therefore, network diagram is essential as it offers the most accurate estimated time for the completion of the project.

Components of a Network

A network helps in prioritising the activities of a project and helps in logical sequence of the activities. The interdependencies of activities are well explained in the network diagram making it easy for a common man to understand the activities involved in the project.

We have already discussed about the head and tail events and activities in the network diagram. The head activity or event is called successor and the tail activity or event is called predecessor. The other components of a network diagram for establishing logical sequences of activities in the network are as follows:

Finish to Start

This component gives a warning that you cannot start the activity till the predecessor activity or the tail event is completed. It shows the dependency of one activity on the other and proves that the activities cannot run simultaneously. The quality of the project will go down and wastage of resources will happen if these activities are run simultaneously. Suppose there are 2 activities X and Y

Duration of X – 3 days
Duration of Y – 1 day

Y has a Finish to Start Relationship with X – Y cannot Start until X Finishes

Start to Start

This component signifies that the predecessor’s activity and the successor’s activity can run simultaneously as there is partial dependency among the activities.

Let us consider two activities X and Y.

  • Duration of X – 3 days
  • Duration of Y – 1 day
  • Y has a Start to Start Relationship with X – Y cannot Start until X Starts

Here, the Project Team will need a total of 3 days to complete these activities.

Finish to Finish

This component signifies that the predecessor’s activity must finish before the completion of successor’s activity. This is avoided in project management.

Let us consider two activities X and Y.

  • Duration of X – 3 days
  • Duration of Y – 1 day
  • Y has a Finish to Finish Relationship with X – Y cannot Finish until X Finishes.

Here, the Project Team will need a total of 3 days to complete these activities.

Start to Finish

This component signifies that the previous activity will begin when the successor’s activity is completed. This is also avoided in project management.

Suppose there are 2 activities i.e. X and Y.

  • Duration of X is 3 days.
  • Duration of Y is 1 day.
  • Y has a SF relationship with A

The diagram below shows SF relationship between X and Y, wherein X is the predecessor and Y is the successor.

As per the Figure 10.6, Y’s Finish is dependent on X’s Start, which means that Y can Finish (F) as soon as X Starts (S). Here, the com- plete sequence is planned to be completed in a total of 4 days.

The dependencies of the activities depend upon the nature and type of the project. The general components of the network are activities, duration, events, and dependencies.

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