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In the concluding part of his two-part article, Satyashri Mohanty, the founding director of Vector Consulting Group, discusses the benefits of using Critical Chain Project Management (CCPM) techniques in the planning and execution of construction projects.

Critical Chain Project Management (CCPM), invented by Dr Eli Goldratt in the 90s offers a radical approach to planning and execution which helps prevent wastage of buffers and at same time leave sufficient to absorb the impact of genuine uncertainties.

CCPM way of planning

Since the paradigm of task level buffers creates wastages, the CCPM way of planning involves, shifting the buffers out from the tasks to the end of the respective path to protect the overall path. The task durations are made seemingly “unrealistic” and the aggressive estimates are not made into commitments.

The buffer at the end of the longest chain/path is called the project buffer while the buffer at end of feeding chains is called the feeding buffers (inserted at point where feeding chains integrate with the longest chain of tasks). The aggregation of buffers from tasks offers the opportunity to reduce the overall buffers while maintaining the same level of protection.

Critical Chain Plan with Buffers

The actual task scheduling the start and end time of the tasks, are not set in the planning. The task scheduling in CCPM methodology is left to execution, after starting the tasks, when people have the best possible information about the tasks. Since task scheduling is left to execution, the focus in CCPM is just good enough planning and very strong execution.

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COMMENT Comment on this article

Bad multi-tasking can be eliminated by controlling the number of open work fronts. If it is an environments of multiple projects then starts of the projects are staggered to avoid the bad effects of multi-tasking.

This step is counter-intuitive to commonly held belief that early start leads to early finish. In an environment of limited resources, an early start does not lead to an early finish, it just leads to increased queues in front of the scarce resources and almost all projects are delayed.

Staggered starts ensures, less projects in progress at any point of time, and full resourcing of those few projects. The rate of output of projects goes up, lead times go down while all projects finish earlier than otherwise.

Proactive Execution

With task level deadlines, it becomes uneasy for management to intervene early on in the task execution. In most environments, the culture of abdication sets in and issues are detected only close to milestones. Contractor issues are managed proactively as managers develop higher tolerance for wastages.

In a CCPM environment, there are no task level deadlines to fall back on. Without task level deadlines the focus shifts on the much needed daily management of work and preparatory of upcoming jobs. Daily, for all open tasks, remaining duration estimates are used to check the buffer consumption and provide signals to succeeding resources on likely start date. The buffer signals are also used to determine the priorities of tasks which in turn helps contractor and managers align resources to the right areas.
 
The priorities are set based on relative consumption of project and feeding buffers, so that resources and limited management bandwidth stay focussed on the current longest chain of the project. The entire organization focuses on ensuring flow of projects rather than managing to milestone. In a conventional management, as long as tasks meet milestones, it is considered a healthy sign.