The Critical Path Method was developed from a combination of ideas from two engineers at DuPont and a U.S. Navy project during the 1950s. Both institutions worked on ways to complete projects more efficiently and with greater accuracy. The result of their concepts is a system of planning that involves mapping out all the steps required to complete a project, and then identifying priorities and timelines for each sequence of events involved. For many projects and industries, a critical path analysis is the ideal approach. However, like everything, CPA has its limitations and can create problems, too.
Characteristics of Critical Path Anlaysis
Critical path analysis differs from other planning methods because of two key characteristics: mapping and identifying potential blockades, also know as critical paths. CPA believes in making a project visual so that all involved can see the sequence of steps, including which actions can occur simultaneously and which are dependent on others in order to commence. The actions necessary to allow or spur other project steps are the critical paths. The critical paths that take the most time or resources get the highest priority. This usually allows a project to be completed in the shortest amount of time possible.
CPA works best with projects that are defined and static. When project planners know their goals, resources and time allotted, they can use CPA to create a solid plan. On complicated engineering, manufacturing or business projects, diagrams can become large and very detailed. The larger the project, the more mapping it entails. Thus, when project plans are in flux or resources change, CPA can become cumbersome and ineffective. In some cases, planners could easily spend weeks retooling a project plan because one or two central aspects change. CPA is not so adaptable.
Of the various potential changes to a project, the worst for CPA is shortening a timeline. After all, projects are mapped out based in large part on time allotted to complete a project. In some cases, CPA is used to determine time required for a project. When a client or manager shortens a timeline, CPA must take what's known as a "crash action" involving reprioritizing each step. In effect, more paths may become critical and planners must usually reprioritize resources.
CPA takes account of what's required to complete a project in the most efficient way possible. It factors time, prioritizes actions and identifies every step required from start to finish. However, it doesn't understand resources and how resources are applied. For example, a project planner may estimate a particular phase of construction will take two months, based on having three cranes. However, the planner using CPA may not know the cost of the cranes and whether a client has the resources to afford three cranes. It may turn out that much later, resources don't match the CPA map and the project begins to unravel. A good engineer or contractor should look for these issues when using CPA and try to work through budget issues to the greatest extent possible in order for planning to succeed.