Project Scheduling: Gantt Charts & Network Techniques¶
Project scheduling is an integral component of project management that involves mapping out exactly when and how projects will be carried out. It ensures that project activities are aligned with the available resources and the project timeline. Two of the most common and effective project scheduling techniques are Gantt Charts and Network Techniques, which include methods like PERT and CPM.
Gantt Charts¶
A Gantt chart is a horizontal bar chart that represents a project schedule. It is a favored tool in project management for scheduling tasks over the duration of the project.
How Gantt Charts Work¶
- Timeline Representation: The chart displays a series of horizontal lines showing the length of time for each task.
- Task Sequencing: It clearly depicts the start and finish dates of the terminal elements and summary elements of a project. Terminal elements and summary elements comprise the work breakdown structure of the project.
- Progress Tracking: By comparing the planned and actual progress displayed on the Gantt chart, project managers can easily spot which tasks need attention.
Advantages of Gantt Charts¶
- Clarity: Gantt charts present complex information in an easy-to-understand visual format, which can improve stakeholder communication.
- Coordination: They help synchronize task transitions, clarifying task relationships and dependencies.
- Motivation: By providing visual milestones, Gantt charts can keep the team focused and motivated.
Network Techniques¶
Network Techniques involve using graphical representations (network diagrams) to plan and monitor the progress of projects. PERT and CPM are two of the most widely used network techniques in project management.
PERT (Program Evaluation and Review Technique)¶
PERT is a method to analyze the tasks involved in completing a project, particularly the time needed to complete each task and to identify the minimum time needed to complete the total project.
- Uncertainty Management: PERT is particularly useful in projects where time estimates for the tasks are uncertain—it uses probability distributions to model these uncertainties.
- Time Estimation: By calculating weighted averages for task duration, PERT can help project managers identify the most probable timelines for project completion.
CPM (Critical Path Method)¶
CPM focuses on identifying the longest stretch of dependent tasks and measuring the time required to complete them from start to finish.
- Critical Path Identification: It identifies the critical path, which is the sequence of stages determining the minimum time needed for an operation.
- Time Optimization: CPM is used to estimate the minimum project duration and to develop a project schedule that is optimal by arranging project activities for the greatest efficiency.
Creating Network Diagrams¶
- List of Tasks: A comprehensive list of all the tasks required for the project is created.
- Sequence Tasks: Tasks are sequenced according to their dependencies—the logical relationships between the end of one task and the start of another.
- Diagram Creation: Each task is represented as a node, and arrows are used to indicate the flow and dependencies between tasks.
Advantages of Network Techniques¶
- Visualization of Dependencies: Network diagrams provide a visual map of task dependencies, which is critical for understanding the complexity of a project.
- Resource Management: They can aid in resource allocation by highlighting resource constraints and availability.
- Flexibility Analysis: Network diagrams make it easier to see where schedules can be compressed or extended, and the impact of these changes on the overall project timeline.
Comparison of PERT and CPM¶
When it comes to project management, PERT (Program Evaluation and Review Technique) and CPM (Critical Path Method) are two prominent techniques used for project scheduling and management. Below is a comparison of their characteristics:
| BASIS FOR COMPARISON | PERT | CPM |
|---|---|---|
| Meaning | PERT is a project management technique used to manage uncertain activities of a project. | CPM is a statistical technique of project management that manages well-defined activities of a project. |
| What is it? | A technique of planning and control of time. | A method to control cost and time. |
| Orientation | Event-oriented | Activity-oriented |
| Evolution | Evolved as Research & Development project | Evolved as Construction project |
| Model | Probabilistic Model | Deterministic Model |
| Focuses on | Time | Time-cost trade-off |
| Estimates | Three-time estimates | One time estimate |
| Appropriate for | High precision time estimate | Reasonable time estimate |
| Management of | Unpredictable Activities | Predictable activities |
| Nature of jobs | Non-repetitive nature | Repetitive nature |
| Critical and Non-critical activities | No differentiation | Differentiated |
| Suitable for | Research and Development Project | Non-research projects like civil construction, ship building, etc. |
Understanding the differences between PERT and CPM is crucial for project managers in selecting the appropriate technique for managing their projects. PERT is more suited for research and development projects where time is a major variable, while CPM is preferred for projects where both time and cost are equally important.
When employing these techniques, it’s important to have detailed project information and clear objectives. Gantt charts are best when a project is relatively simple or when communicating high-level timelines to stakeholders. In contrast, network techniques are more suitable for complex projects with many interdependent tasks that require detailed time analysis. By choosing the appropriate scheduling technique, project managers can significantly enhance their ability to deliver projects on time and within budget.
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