Organizational Breakdown Structure (OBS)

An Organizational Breakdown Structure (OBS) is a hierarchical representation of the project organization that maps project activities to the organizational units responsible for performing them. It visually connects the people or departments in the organization to specific parts of the project work.

The OBS facilitates responsibility assignment and ensures alignment between the project structure and the organization’s operational framework.

Key Aspects of an OBS

• Hierarchical Structure – Shows reporting and responsibility relationships
• Activity Mapping – Links work packages or activities to the performing unit
• Responsibility Tracking – Used with RACI or other matrices for clarity
• Integration with WBS – OBS complements WBS to show who does what

Example Scenarios

• Assigning work packages in a large engineering project to department leads
• Mapping project scope to regional business units for global execution
• Creating input for a Responsibility Assignment Matrix (RAM)

Mermaid Diagram: Example Organizational Breakdown Structure

flowchart LR
    ORG[Organization]
    ORG --> PMO[Project Management Office]
    ORG --> ENG[Engineering Department]
    ORG --> OPS[Operations Department]
    ENG --> ENG1[Design Team]
    ENG --> ENG2[Development Team]
    OPS --> OPS1[Logistics Team]
    OPS --> OPS2[Support Team]
    ENG1 --> WBS1[Work Package A]
    ENG2 --> WBS2[Work Package B]
    OPS1 --> WBS3[Work Package C]
    OPS2 --> WBS4[Work Package D]

Why Organizational Breakdown Structure Matters

• Clarifies Accountability – Connects tasks to responsible organizational units
• Improves Oversight – Enables targeted management and resource allocation
• Supports Reporting – Facilitates communication across departments
• Enables Governance Alignment – Links project work to formal authority structures

See also: Resource Breakdown Structure, Risk Breakdown Structure, Work Breakdown Structure (WBS), Responsibility Assignment Matrix, Project Governance.