The Critical Path Method in project planning

The Critical Path Method is a step by step technique that is used to schedule a set of project activities. It analysis what activities are least flexible and the project duration is predicted based on the activities that fall along the critical path. The critical path is the longest sequence of activities in a project plan which must be completed on time in order for the project to complete on the predetermined scheduled date . By delaying an activity on the critical path leads to a delay on the completion time of the entire project as these activities have no slack. Activities along the path cannot start until the predecessor activity is completed. When using CPM to plan a project a graphical diagram is often represented showing how each activity is related to the others . This method is one of several tools that is important to keep the project on track and is convenient for all forms of projects, including research projects, product development, construction industry, maintenance and many more.

A joint venture between the Dupont chemical company and computer firm Remington Rand Univac led to a development of the Critical Path Method in the 1956 to tackle the interrelationships of separate activities within a project schedule .

In this article the Critical Path Method (CPM) is described, a step by step guidance on how to apply the method is discussed and the tradeoff between cost and time are analyzed. Furthermore, a comparison to other project management techniques is performed and its limitations and advantages are addressed.

Overview

Introduction and purpose of CPM

“A project is a temporary endeavor undertaken to create a unique product or service” bls 4. The major goal of a project is to satisfy customer’s needs and achieve an organization’s strategic plan. Projects are unique as they are different in some distinguishing way from all other projects. They have a life cycle were the life span is limited and there are predictable changes in level of effort and focus over the life of the project. Project life cycle generally passes sequentially through four stages: defining, planning, executing and delivering. This is illustrated in Figure x. bls 7

To meet project requirements, it is important to have a good knowledge of project management. “If you fail to plan you are planning to fail” is a phrase often used. This can be related to project management, which is an application of knowledge, skills and a set of tools that improves the ability to plan, implement, and manage activities to accomplish specific organizational objectives. Not only is project management a set of tools, it is also a results-oriented management style that places a premium on building collaborative relationships among a diverse cast of characters bls 3.

When managing projects, it is crucial to have a good understanding of the Triple constraint (also referred to the Project Management Triangle). These constraints, time, scope and cost, form a triangle with a quality in the center as can be seen in figure x(fá heimild???). They are all fully inter-related, which means that if one side is altered the other two attributes will be affected in some manner. These constraints must be handled effectively for successful completion of any project as well as for the company to meet their customer quality requirement [1]. In order for this to be fulfilled the CPM technique can be useful.

The Critical Path Method (CPM) is one approach of the project network techniques used for planning, scheduling and monitoring project progress. The relationship between each activity is represented in a graphical diagram. The diagram depicts the project activities that must be completed, the logical sequences, the interdependencies of the activities to be completed, and in most cases the times for the activities to start and finish along with the longest path through the network- the critical path. This is the framework for the project. bls 157.

History

In the 1950’s The Critical Path Method was developed by a Dupont engineer, Morgan R. Walker and a Remington-Rand computer expert, James E. Kelly, Jr. They created a unique way of representing the operations in the system, which involved using unique arrow filled diagrams [2]. At the similar time, the U.S. Navy initiated a project called Program Evaluation Research Task (PERT). The purpose of that was to provide naval management with an effective manner by which they could periodically evaluate the information of the new Fleet Ballistic Missile program. With this the US Navy could obtain valid information of the progress of the project and also have a reasonable accurate projection of the completion of the project as desired. It is worth mentioning that PERT does not include the quantity, quality and cost information, it only deals with the time constraints 11. PERT-CPM was a successful tool for the hardware-oriented programs, but its application in resource management problems was limited. As CPM techniques were modified and designed to operate on the smaller new computer systems, they proved useful in smaller projects such as design and marketing of new products, maintenance and shutdown schedules, and research and development programs [3].

In today’s technology century there are several project management software that can be chosen from to solve complex projects, such as Microsoft project. Despite that, it is important as a project manager to have a deep understanding of how to apply the CPM techniques by hand.