Structure Planning Communication: Risk Breakdown Structure and Resource Planning

PMBOK v8 Definition

The Resource Breakdown Structure (RBS) is a hierarchical representation of resources by category and type, as shown in Figure 4-4 of PMBOK v8. The Risk Breakdown Structure (RBS) is a hierarchical representation of potential risk sources, organized by category, as illustrated in Figure 4-5. These breakdown structures are planning tools that enable systematic identification, organization, and communication of resources and risks within a project. Both are created during the planning process group and serve as foundational inputs for subsequent project management activities.

Why It Matters for the Exam

The RBS and Risk RBS appear frequently in PMI exam questions testing your ability to distinguish between different breakdown structures and understand their specific purposes. Questions typically appear in the Planning process group domain, especially in resource management and risk management contexts. The exam often tests whether you know which breakdown structure to use for which planning purpose, and how these structures support effective communication of project plans.

Key Points to Remember (for the exam)

• Resource Breakdown Structure Purpose: Hierarchically organizes resources by category (e.g., labor, materials, equipment) and type—NOT by organizational department or work package
• Risk Breakdown Structure Purpose: Hierarchically organizes potential risk sources by category (e.g., technical, external, organizational)—NOT individual risks or risk responses
• Common Confusion: RBS (Resource) vs. RBS (Risk)—both use the same acronym but serve completely different planning functions
• Key Difference: Resource RBS focuses on what you need to do the work; Risk RBS focuses on what could go wrong
• Communication Value: Both structures enable clear, standardized communication of complex planning information across the project team and stakeholders
• Hierarchical Nature: Both are hierarchical—the top level is broad categories, lower levels provide increasing detail
• Tailoring Application: The level of detail in both structures should be tailored to project size, complexity, and stakeholder needs

Typical PMI Exam Example

A project manager is planning resource requirements for a construction project. Which breakdown structure should they use to organize labor, materials, and equipment by category? Answer: Resource Breakdown Structure (RBS). The project manager would later use a Risk Breakdown Structure to categorize potential risk sources like weather delays and supplier issues.

PMI Exam Traps

• Trap: Confusing Resource Breakdown Structure with Work Breakdown Structure (WBS)

  • Reality: WBS organizes deliverables; RBS organizes resources needed to create those deliverables

• Trap: Thinking Risk Breakdown Structure lists individual risks

  • Reality: Risk RBS lists risk categories and sources, not specific risk events or their impacts

• Trap: Assuming both RBS types are interchangeable

  • Reality: Resource RBS and Risk RBS are distinct tools for different planning domains—never use one for the other's purpose

• Trap: Believing breakdown structures are only for large projects

  • Reality: PMBOK v8 emphasizes tailoring—even small projects benefit from simplified versions of these structures

Important PMI Connections

Quick Review Questions

1. A project manager needs to organize all potential sources of technical and external risks. Which breakdown structure should they use?
2. What is the primary difference between a Resource Breakdown Structure and a Work Breakdown Structure?
3. During which process group are both the Resource RBS and Risk RBS typically created?
4. A team member confuses the acronym "RBS" for resource planning. What is the correct interpretation in a risk management context?
5. Why would a project manager tailor the level of detail in a Resource Breakdown Structure?

PMBOK v8 Reference

Section 4.2 - Plan Resource Management (Resource Breakdown Structure – Figure 4-4) Section 4.3 - Plan Risk Management (Risk Breakdown Structure – Figure 4-5) Section 5.1 - Relationship Among Product Vision, Release Planning, and Iteration Planning (Figure 5-1) Section 5.2 - Communication Model for Cross-Cultural Communication (Figure 5-2)