Critical Path Analysis

• Projects often involve working towards some aim, with a set amount of time and resources.
• Being able to efficiently review progress, and communicate with the team members, and organization, are important for good project management.
• When the project is a risky or important one, it is important to ensure that the project is completed successfully.
• To ensure that time and resources are not wasted, managers would want to plan projects efficiently.
• Managers do not want people (workforce) and machines sitting idle, or supplies being delivered well before they are needed.
• Any delays would cost money.
• Definition - Critical path analysis, also known as network analysis, is a project planning method that visually organizes the different tasks in a project, based on their dependencies on each other. This is done to find the most efficient means of completing the task. The tool also allows for recognizing tasks with “no float time”, meaning if these tasks are delayed, it would affect the project’s end date, due to which they must happen in the set time.
• Aim - To find a means of completing the project in as short a time as possible.
• Steps -

  1. Identify the different tasks involved in the process.
  2. Estimate the estimated length of time each task will take.
  3. Determine the order in which the tasks can be completed. Which ones are dependent on each other, and which ones can happen in parallel.
• The Network Diagram

  • Has nodes (circles), at the start and end of an activity (like a milestone, or bus stop).
  • A line representing the activity. With the name above the line, and duration under.
  • The diagram begins with one node and ends with one node.
• EST - Shown at the top right of a node.
• • EST - Is the earliest time a particular activity can begin. To be more specific, the earliest time the activity on the right of the node can start.
  • Add the previous node’s EST to the duration to get the next node’s EST.
  • Calculated left to right.
• For EST - When two activities are leading to one node, pick the bigger duration or value.

  • If activity C is dependent on both activity A and B, even if B is finished before A, it does not matter as C can still not start.
• EST - Usecase

  • Helps identify when resources are likely to be needed for a particular activity. Avoids having staff and supplies arriving too early and being idle, taking up space and costing money. Or arriving too late, and delaying the whole project, which also costs money. To conclude it helps ensure people and materials are coordinated and ready at exactly the right moment.
• Latest Finish Time

  • Shown at the bottom right of a node.
  • Is the latest an activity can finish without holding up the whole project.
  • Deduct the duration from the LFT of the node on the right to get the LFT of the left node.
  • Calculated right to left.
  • When two activities are leading to one node, pick the smaller duration or value.
• Free Float

  • How an activity can overrun without delaying the next activity.
  • Free Float = EST of the next node/activity - EST of the activity being considered - the duration
• Total Float

  • How much an activity can overrun without delaying the whole project.
  • Total Float = LFT of the activity (node on the right) - duration - EST of the activity (node on the left)
• Critical Path

  • Shown by placing small double lines (verticle =), on the activities along a critical path.
  • Critical activities have a float of 0. They are heavily monitored by the managers. As any delays in them will delay the whole project.
  • A critical path is a series of activities, with the least or no float. It shows the minimum project duration, in other words, the shortest time in which a project can be completed.
• Dummy Activities

  • Shown using a dotted line.
  • They are used in a project with complex dependencies/relationships between activities. They help visualize a seemingly logical relationship between two “real” activities, with a dummy one that has no costs or duration.
• Cons

  • The durations are estimates identified by the managers. At times, these estimates are exaggerated to meet a set deadline or are over-optimistic as there are no similar prior projects to base it upon. Which would provide inaccurate and not reliable calculations for the ESTs, and LFTs.
  • “Garbage in, garbage out”
  • Does not consider external factors, like suppliers.
  • Shows the quickest way, but not always the best. As trying to finish activities fast, might result in workers producing poor quality products.
• Pro

  • The managers must consider exactly what activities are a part of the project. Meaning they would need to consult different departments. This ensures that the manager did not forget to consider a certain aspect of the project. Furthermore, the workers who have been consulted also get a better understanding of the project timeline, making them more involved in the completion of the project.
• • Pros
  • Can help plan launch arrangements. In cases where projects involve a new product line for a business, information like - when is the earliest the project can be completed, allows for release date announcements to customers.
  • Help managers decide whether or not certain deadlines can be met.
• • Pros
  • Activities that need the most attention, the critical ones are identified. Allowing for resources from non-critical activities to be distributed to the critical ones, in order to ensure no delays occur.
  • Helps gain a possible competitive advantage. As managers may be able to produce items or develop products more quickly than the competition.
• • Pros
  • A good starting point, or framework to review a project’s progress with. At times when delays are caused due to external factors, this tool ensures that the manager is not caught unaware when the whole project’s end date is delayed. As the ESTs and LSTs can be calculated again according to the changes to identify the impact and attempt to get the project back on track.
  • Helps with forward planning.