Project Management Methodologies: What are CPM, CCPM, and APF?
August 13th, 2020 in Productivity
Examining More Project Management Methodologies
There are many project management methodologies to choose from with each having their pros and use cases. Many of these methods relate to Agile, which was reviewed in the first article. In this article, learn about the difference between Critical Path Method (CPM) and Critical Chain (CCPM). Adaptive Project Framework (APF) will also be outlined.
Both CPM and CCPM are project management methodologies that use project scheduling and algorithms. APF, on the other hand, accommodates the “unknowns” in a project.
Project Management Methodologies #1: Critical Path Method (CPM)
According to the Harvard Business Review, CPM is a “simple technique for analyzing, planning, and scheduling large, complex projects.” The idea is to determine the project’s tasks that are critical in relation to their effect on total project time and then figure out how to schedule all the tasks to meet the target date at the lowest cost.
CPM employs an algorithm, EF = ES + t where S is the start time for a project, ES is the earliest starting time for a task, and t is the time to complete the task. The earliest finish time is EF. Forward pass analysis determines the early start (ES) and early finish (EF): (ES + duration (DU) = EF). Backward pass determines the late start (LS) and late finish (LF): (LF – DU = LS).
Although computer programs exist for CPM, the method can be illustrated using a graph. Each task necessary is listed with a unique identifying symbol, the time to complete the task, and the prerequisite jobs. The tasks are placed in “technological order” where the tasks only appear if their predecessors have been listed. Arrows are used to indicate sequence relationships between tasks. “Start” tasks have no predecessors and “Finish” tasks have no successors.
The critical path(s) is the longest path (time-wise) from start to finish. It indicates the minimum time needed to complete the entire project. It includes only critical jobs.
How to Implement:
- Outline all the tasks and time needed for each task
- Organize the task into a table with job number (letter or number), the description, the immediate predecessors of that task, and the normal time the task takes. “Immediate predecessors” determines the sequence relationships of the tasks
|Job No.||Description||Immediate Predecessors||Normal Time (days)|
|b||Excavate and pour footers||a||4|
|c||Pour concrete foundation||b||2|
- Draw the graph by starting with “Start” and add in tasks using circles that indicate the job number and time requirement. Make sure the tasks are in sequential order. Draw a connection between the tasks using arrows (the thicker arrow indicates the critical path)
- To compute ES and EF time using the graph:
- Mark the value of S beside Start
- Mark new tasks (whose predecessor has been marked) with the largest number of any of its immediate predecessors (the number is the early start time) on the left
- Add task time to the early start time and mark the result (EF time)
- Continue until the Finish
- Compute late finish (LF) time:
- Mark the value of T (project’s target due date) beside Finish
- Mark new tasks (whose successors have been marked) with the smallest LS time of its immediate predecessor on the right
- Subtract this new number from the task time and put it on the left of the task
- Continue until Start
- Total Slack (TS) is the difference between a task’s early and late start. It is the max amount of time a job may be delayed beyond its early start without necessarily delaying the project completion time. Critical tasks have zero total slack
- If T (target date) is greater than F (early finish date of whole project), critical tasks have a TS equal to T minus F
- All noncritical jobs have a greater total slack
When to Use it:
Use CPM to have a visual representation of a project and to see which tasks are dependent on another. The graph is also beneficial to see the critical path and the time needed to finish the project. CPM enables project managers to measure progress against the project’s plans.
Project Management Methodologies #2: Critical Chain Project Management (CCPM)
Critical chain is used to modify the project schedule for limited resources “by adding duration buffers that are non-work schedule activities to maintain focus on the planned activity durations.” Its focus is on managing the buffer durations against the duration of the task chains.
After the critical path is determined, Critical Chain is completed by entering the resource availability. The schedule that is produced outlines the resource-constrained critical path. This new path is an altered version of the original. Critical Chain scheduling starts at the due date of a project and works backwards to ensure the most critical work is done first.
Critical Chain uses three types of buffers: project buffer, which is the total pooled buffer, the feeding buffer, which is the pooled buffer on each path, and the resource buffer, which is inserted before a critical chain task that requires critical resources.
How to Implement:
- Create a critical chain (path) using CPM
- Outline time buffers for each task, pool these task buffers, and add them to the end of the critical path
- Use Resource Buffers to ensure the arrival of Critical Chain resources
- Place Feeding Buffers on all paths that feed the Critical Chain to protect the Critical Chain from accumulation of negative values (e.g. loss of time)
- Gate tasks (tasks with no predecessor) as late as possible to prevent multitasking
- Make sure resources work as quickly as possible on their tasks
- Provide resources with task durations and estimated start times
- User buffer management to control the plan
When to Use it:
Use CCPM in projects that are highly dependent on sequential tasks. CCPM focuses on bottlenecks.
Project Management Methodologies #3: Adaptive Project Framework (APF)
Adaptive Project Framework focuses on accommodating the unknowns in a project and preparing the team to anticipate and respond to them. One of the core principles is “learning by doing.” The idea is to continually learn by re-evaluating the results and decisions in a project. Regular communication with stakeholders is a must for effective adaptation.
With APF, smaller goals are set in stages, which lets the project’s final outcome and deliverables evolve over the course of the project. It maximizes business value by adjusting the scope at each stage. At the start of the project, the budget and time are set, and the client and project manager collaborate on a better business solution. At each increment in the project, the client provides their opinion and validates the increment.
How to Implement:
- Project scope: Commit to the project’s goals with the client. Outline the project’s scope, form a team, set a budget, and outline the cycle plan schedule and work breakdown structure
- Cycle plan: Plan out cycles and meet with the client on a set schedule to revise the upcoming cycle priorities. Assign resources to sub-teams and create just-in-time planning schedules
- Cycle build: Allow sub-teams to execute their tasks without alterations or delays. Reassign unfinished tasks to future cycles and abandon cycles that wastes time and money
- Client checkpoints: Host client checkpoints to discuss the project’s progress and their opinion on the deliverables. Revise the cycle plans based on the feedback. Repeat the cycle plan, cycle build, and client checkpoint
- Post-version review: After the project is complete, write and archive reports on the learned lessons and best practices for future consideration
When to Use it:
Use APF for projects that require a lot of flexibility and client input. It is also beneficial for collaborative processes with multiple stakeholders at every level.
Harvard Business Review. The ABCs of Critical Path Method.
PM Learning Solutions. Critical Path vs Critical Chain.
Simplilearn. What is Critical Chain Project Management
Project Management Institute. Course correction.