What Is Critical Chain?

Critical Chain Project Management (CCPM) is a project management methodology rooted in the Theory of Constraints (TOC) developed by Eliyahu Goldratt. It has become the preferred choice for industries that deal with high levels of complexity and uncertainty.

While project outcomes are challenging to measure objectively, works such as “Advanced Multi-Project Management” (2013) by Gerald I. Kendall and Kathleen M. Austin document significant improvements, including 39% shorter project durations and 70% more projects completed in the same timeframe.

The Theory of Constraints (TOC)

The TOC emphasizes that every system's performance is constrained by a small number of bottlenecks (typically one). Its five focusing steps aim to identify and alleviate these constraints to improve overall productivity:

1. Identify the constraint.
2. Exploit the constraint.
3. Subordinate everything else to the constraint.
4. Elevate the constraint.
5. Repeat the process.

When applied to project management, CCPM identifies the constraints limiting project delivery speed and addresses them holistically. Below, we’ll explore the five steps of TOC in the context of Critical Chain and highlight its unique advantages—especially in the IT industry.

1. Identify the Constraint

In CCPM, the "constraint" is the Critical Chain—the longest sequence of dependent tasks, considering both task and resource dependencies.

Comparison with Critical Path

The Critical Path method (CPM) focuses only on task dependencies and ignores resource constraints. If resources were infinite, CCPM and CPM would yield identical results. However, in real-world projects, resource availability is often a critical factor, which CCPM addresses effectively.

Comparison with Agile

Agile methodologies like Scrum and Kanban focus on different aspects. Scrum prioritizes team throughput (measured by velocity in story points per period) and sprint efficiency (making sure everyone has enough tasks to be busy), while Kanban emphasizes process visibility and limits Work in Progress (WIP). These approaches are ideal for managing tasks with minimal interdependencies, such as bug fixes or minor enhancements. However, they lack the holistic focus on overall project duration that CCPM provides.

Summary

While Agile and Critical Path each address specific project needs, CCPM offers a comprehensive approach by considering both task and resource dependencies, ultimately optimizing project delivery timelines.

2. Exploit the Constraint

Exploiting the constraint involves maximizing the efficiency of the Critical Chain before adding additional resources. Here’s how CCPM addresses key challenges:

Multi-Tasking

Multi-tasking often delays task completion. The image below illustrates this:

In the top scenario, tasks are executed in parallel, while in the bottom scenario, they are completed sequentially. Sequential execution delivers value faster (e.g., revenue or insights) and avoids the overhead caused by context switching.

Unlike Agile, which may inadvertently encourage resource multi-tasking on project level (e.g., fixing bugs while working on new projects), CCPM avoids or minimizes it by accounting for resource dependencies.

Task-Level Safety

When estimating tasks, people often assume a normal distribution for task durations:

However, in dynamic environments like software development, tasks often follow a log-normal distribution. This results in some tasks taking significantly longer than estimated, even when others finish early. To compensate, people build excessive safety into individual task estimates:

CCPM takes a different approach by requiring optimistic task estimates (50% probability of on-time completion) and protecting the project with a Project Buffer. This centralized safety mechanism reduces project duration by approximately 25%, even with a 50% buffer.

Student Syndrome

Student Syndrome (planned procrastination) occurs when intensive work starts only as deadlines approach. This is often due to safety in the task durations:

CCPM mitigates this issue through optimistic task estimates, which Agile and Critical Path methodologies fail to address.

Parkinson’s Law

Parkinson’s Law states that "work expands to fill the time available." This leads to unnecessary polishing or effort, delaying task handoffs:

CCPM counters this by fostering a "Relay Runner" culture, encouraging immediate task handoffs, similar to Kanban's flow management.

3. Subordinate Everything Else to the Constraint

Delays tend to accumulate in projects, while early gains are often wasted:

To address this, CCPM introduces Feeding Buffers at integration points to protect the Critical Chain. These buffers ensure resource focus and prevent unnecessary multi-tasking:

Neither Agile nor Critical Path methodologies provide comparable mechanisms to address this issue, further highlighting CCPM’s superiority.

4. Elevate the Constraint

When all exploitation measures are exhausted, CCPM empowers teams to allocate additional resources, reassign tasks, or even temporarily increase work hours to accelerate project completion exactly where it matters.

Unlike Agile, where "heroic efforts" often stretch entire teams, CCPM provides clear visibility into the Critical Chain, allowing targeted interventions that minimize disruption.

5. Repeat the Process

As the constraint changes (e.g., due to project progression or resource adjustments), the process is repeated to maintain high performance.

Critical Chain Project Execution and Control

Beyond scheduling, CCPM excels in execution and control through tools like the Fever Chart, which tracks project health using two key metrics:

1. % Project Completion
2. % Buffer Penetration

In AgileCCPM for Jira, the Fever Chart offers two views:

Snapshot View

Provides a real-time summary of project health:

History View

Tracks trends over time for deeper analysis:

Fever Chart Zones

The chart categorizes buffer penetration into three zones:

1. Green (Watch): Progress is on track.
2. Yellow (Plan): Prepare corrective actions.
3. Red (Act): Immediate intervention required.

This visual tool enables proactive, data-driven decision-making to ensure project and portfolio success.

Summary

Critical Chain Project Management (CCPM) delivers unparalleled results for projects requiring strict adherence to deadlines or where shortening project duration results in substantial benefits, making it especially valuable in IT.

While Agile excels at managing smaller, independent tasks, it lacks the visibility and optimization needed for larger, interdependent initiatives, and we explore it in detail in our Escaping the Scrum Trap: Why IT Companies Need CCPM post. Similarly, traditional methodologies like Critical Path fall short in addressing resource dependencies and project uncertainty, and we explore it in detail here.

AgileCCPM for Jira bridges this gap, bringing the power of CCPM to the world’s most trusted task management platform. Now, IT companies can seamlessly integrate CCPM for strategic initiatives while continuing to leverage Agile for day-to-day activities—all within a unified, native experience.