Program Evaluation and Review Technique (PERT) is a project network analysis technique used to plan and control large construction projects.
PERT focuses on the relationship between the time each activity takes, the costs for each activity and the resulting time and cost for the expected completion of the entire construction project. This helps in understanding the performance of the work throughout the course of the project.
PERT is an event oriented project scheduling techniques. The method does not show any kind of inter-dependencies. It only shows an event, which is represented in terms of the time and the resources that are necessary for the completion of that event. It does not possess any historic chain.
PERT gains a lot of benefits, that facilitates the project management team. But it also shows certain disadvantages that must be taken into consideration by the project managers. The pros and cons of PERT techniques are mentioned in the following section.
Advantages of PERT in Construction Management
Use of PERT in construction project has following advantages:
- Facilitate planning of large projects
- Critical Path of construction project is visible
- Helps in activity Analysis
- Better coordination
- What-if Analysis
Facilitate Planning of Large Projects
The program evaluation and review technique enables the project manager to schedule the project very easily. It is mainly active in the case of a large project.
To be more precise, it such requires three elements to define the event. What is the time required to do that event, what comes after the event and what comes before the event? This makes the scheduling easy and clear
Critical Path is visible
The PERT method shows the critical path in a clearer manner. The critical path is the path whose activities cannot be delayed.
An easy understanding of slack values with limited conditions of dependencies make the project manager take a fast and good decision which would favor the performance of the project.
A project manager views information about the likely completion of a project on time and on a budget by viewing PERT activities and events independently and in combination.
PERT facilitates integration and data submission from various department of the construction organization. This will improve the planning and the decision-making capabilities of the project team.
A Large amount of data which gains qualitative, as well as quantitative values, are combined which helps in proper coordination of the project. This help in good communication between different departments, as lack of communication, is one of the important factor affecting the development of an organization. This clearly helps in identifying the responsible roles of everyone in the whole team.
A what-if analysis identifies possibilities and uncertainties related to project activities, which is read from the formation of critical paths.
Many sets of permutations and combinations are performed differently with the activities and the most useful possibility selected. The set with minimum cost, best result and economy is chosen. It also helps us to identify the activity that is a risk.
Disadvantages of PERT in Construction Management
- Subjective Analysis
For a new project, the method requires data to identify the activities. This is found to be difficult because the new project chosen are not repetitive in nature. It would be a rare or fresh project idea. This makes the data collection to be subjective in nature showing lesser accuracy in the time or cost estimated.
The source of data obtained, have chances of biasing and are found unreliable. As mentioned, because of the not repetitive nature of the project, there is no guaranty in bringing information from a past historic record with similar cases in certain situations and implementing it.
- Time Focused
PERT is a time oriented method. It just makes use of the time that is required to complete the activity. Hence the determination of time for each activity and its allocation is of great importance. It’s based on an assumption and will work well if it is right. Else problems arise.
- PERT technique is labor intensive in nature
- When two or more projects share available resources, the technique won’t work good or makes it complicated.
- Any change in the precedence and sequential relationships of project activities will result in the failure of this method.
- With the increase in project activities, it makes the chart complicated with hundreds of task dependencies.
- Expensive in nature
- Prediction Inaccuracy
When a project with no past records or assistance exists, predictions play a role in the movement of the project. Inaccurate decisions and predictions would make the overall project to a total loss. This cannot be done by trial and error with the assumptions.