Project Management & Planning Articles

Critical Chain Project Management. No More Padded Cells!

by Hadley Jones
Published on 21 August 2014

sciforma critical chain project managementEver since the first project manager experimented with a spreadsheet, people have been padding task estimates with "safety margins." In the world of critical paths and PERT charts, it's understandable. The order of the tasks is what counts and rigid scheduling is what keeps things in order. Or at least, that's the theory. However, from this point of view, time can't be saved if one task finishes early. That extra time is unavailable for use elsewhere.

Critical Chain Project Management (so that's CCPM with 'Chain' instead of 'Path') turns this situation around. It makes task start times flexible and aims for balanced loading of resources. The duration estimates in CCPM are reduced by half for the individual tasks. The extra time generated is then made available to the project as a whole. Sciforma is a project management app with this functionality built in, and it also handles Waterfall and Agile project management methodologies too. An add-on module is available for Microsoft Project to give it CCPM capability.

Wrikeand Liquid Planner also offer possibilities to manage chains of dependencies.

Dr Goldratt Tells It Like It Is

CCPM is the brainchild of Dr Eli Goldratt. He saw how many projects under-delivered while overstepping both budgets and schedules. Traditional project management methods too often encouraged a waste of resources due to:

  • Parkinson's Law. A humorous observation that "work expands to fill the time available," but so true.
  • Student Syndrome. Waiting till the last possible moment (or later) before starting a task with a deadline.
  • Bad multi-tasking. Multi-tasking rapidly leads to wasted time in switching between and getting back up to speed with tasks.
  • Lack of prioritization. Traditional PM methods encourage an overall view of a project (which is necessary) and the need to finish tasks on time, but may not promote the desirability of finishing tasks early.

Goldratt's big insight was that projects are in truth planned and executed by people, not computers (even if they use software apps to help them.) His CCPM and "Theory of Constraints" are the building blocks for the Critical Chain PM functionality in Sciforma, for example.

Aren't Padded Cells just for the Crazy?

"Safety" gets built into individual tasks in an effort to protect delivery dates in the event of unforeseen problems. Even when there are no problems, time estimates are still padded the next time - just in case. The padding also gets used up wastefully for the reasons given above. Delays are then passed on to the whole project. Statistics show that:

  • Less than half of projects finish on time-just 44 percent says a survey by the Standish Group.
  • It takes more than twice as long to finish the others compared to the plan-222 percent of scheduled time.
  • They cost almost twice as much-189 percent-as was originally budgeted.
  • More than two out of every three-70 percent-projects under-deliver.
  • About one-third of projects are canceled before completion.

Stay sane and cool with handy project management app comparisons from GetApp to pick the solution that can save you from the perils above. Try side by side descriptions of Sciforma and Wrike, for example.

How Does Critical Chain Project Management Work ?

CCPM works backward. Starting at the end of the project, estimates are made for each task without the extra safety padding. The estimates are made based on experience, judgment and probability of the task being accomplished within the time allotted. Some room to maneuver is then added between different projects. The effects of reducing the individual safety buffers are:

  • Task duration is reduced. Work may still expand to fill the time available (Parkinson's Law), but now that time is shorter.
  • Task immediacy is increased. This cuts down on Student Syndrome, because the task must be tackled 'now', without the option of delaying the start time.
  • Multi-tasking is reduced. Appropriate resource leveling means project managers no longer try to flip resources from one task to another in a desperate effort to have them finish on time.
  • Early and late-finishing tasks balance out. CCPM recognizes that some tasks may still be delayed, but also knows that others may finish early. The early finishers "give" their unused to time to the late finishers, allowing the entire project to come in on time, as planned.

These are the notions that drive the CCPM implementation in Sciforma, and the additional functionality available for Microsoft Project, Liquid Planner and Wrike.

Buffers and Priorities in CCPM

Buffers still exist in CCPM in order to provide sufficient, but not extravagant safety. There are three types:

  • Project Buffer. Between the last task and the project completion date. May be used if there are delays in the longest chain of tasks where starting each task depends on the previous one in the chain being completed (the critical chain).
  • Feeding Buffer. Between the last task in a 'feeding path' (sub-chain of tasks feeding into a given point of the critical chain) and the critical chain.
  • Resource Buffer. Used in parallel with the critical chain to guarantee people and skills required to maintain progress on the critical chain without delay.

The priority for any resource assigned to more than one task is to first complete any task directly affecting progress along the critical chain. In addition, tasks are not left incomplete. This avoids wasteful multitasking.

CCPM or CPPM - What Should You Use?

Critical chain project management (CCPM) offers information and insights that CPPM (critical path project management) practitioners might not otherwise get. Instead of doggedly increasing the amount of detail in the planning of tasks, which was the previous approach to tackling project delays, CCPM simplifies and streamlines. And instead of assuming that large safety buffers per task are a fatality, CCPM offers a technique to make project schedules lean and efficient by paying suitable attention to the human factor that is fundamental to performance. However, CCPM can also be used as an additional point of view for project management, rather than a replacement for CPPM methods. By multiplying the angles like this, project managers can get even better understanding and perception of their projects overall.

CCPM Added Value

In particular, CCPM can bring project managers additional information about:

  • Increasing efficiency in project schedule networks
  • Assessing risk associated with project schedules
  • Automatically handling the probability (inevitability) that project planning will miss or misjudge at least one element, and therefore never be perfect.

Whether your preference is for CCPM, CPPM or both, find out more about project management apps to suit your enterprise with this project management software infographic. Then check out the different Project management app reviews, and see how free trial versions might also accelerate your decision for the PM app that best meets your requirements.


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