19.2 Organisational Breakdown Structure and RACI
Key Takeaways
- The organisational breakdown structure decomposes who is available; crossing it with the work breakdown structure produces the responsibility assignment matrix.
- Responsible means does the work; accountable means answers for the outcome; consulted means two-way input; informed means one-way notification.
- Each work package must have exactly one accountable person — multiple accountabilities mean nobody is accountable.
- Common errors include no accountable role, several accountable roles, over-consultation that stalls decisions, and a matrix never updated after the team changes.
- A RACI is only useful if the named people have seen it and accept the roles it assigns them.
Outcome 21b is precise about the relationship: understand how an organisational breakdown structure is used to create a responsibility assignment matrix (RACI). The mark is in the word used to create — the OBS and the WBS are the two inputs, and the RACI is what falls out when you cross them.
Organisational breakdown structure (OBS)
An organisational breakdown structure (OBS) is a hierarchical model of the organisation that will deliver the project — roles, teams, functions, suppliers, and sometimes governance bodies — used to show who exists to take work and accountability.
| OBS feature | Description |
|---|---|
| Hierarchy | From sponsor/board or PMO down through project manager, workstream leads, teams, and key suppliers as appropriate |
| Roles not only names | Enduring role boxes (Design Lead) with named incumbents where known |
| Project vs functional lines | In matrix organisations, OBS may show project structure while functional managers still own staff development and often allocation |
| External parties | Critical suppliers or partners appear where they hold delivery responsibility |
| Link to WBS | OBS provides the "who" side of the responsibility matrix; WBS provides the "what" |
Why OBS matters
- Visibility of delivery organisation — gaps in roles become obvious (no test lead, no commercial manager).
- Basis for RACI — you cannot assign accountability to work if the organisation model is undefined.
- Resource ownership — clarifies whether people report to the project manager, a functional head, or a supplier.
- Communication and escalation — shows paths for decisions and issues.
- Assurance — reviewers can test whether the organisation matches the risk and scale of the work.
OBS is not the WBS. WBS decomposes work/products; OBS decomposes organisation. Confusing them produces activity lists mistaken for accountability charts, or org charts with no link to deliverables.
WBS (what work) × OBS (who/roles) → Responsibility assignment matrix (RACI)
Scenario B — missing OBS role
A transformation WBS includes "data protection impact assessment" and "cutover runbook," but the OBS has only developers and a project manager. Nobody owns information-governance or operational-readiness roles. Work stalls or is done poorly. Building the OBS would have surfaced the need for a DPO liaison and a BAU operations lead before the schedule committed those packages.
Responsibility assignment matrix and RACI
A responsibility assignment matrix (RAM) maps work breakdown elements to organisational roles. The most common form in PMQ teaching is RACI.
| Letter | Meaning | Practical rule |
|---|---|---|
| R — Responsible | Does the work; may be more than one person/role | Clear task ownership; enough capacity to execute |
| A — Accountable | Ultimately answerable for completion and quality; one A per work package | Approves or owns the outcome; the "buck stops here" |
| C — Consulted | Two-way input before/during the work | Limited to those whose expertise materially affects the result |
| I — Informed | One-way updates on progress or decisions | Keeps stakeholders aware without meeting overload |
Constructing a RACI
- List WBS work packages (or key activities/deliverables) as rows.
- List OBS roles as columns (not every named individual if roles are stable).
- Assign R, A, C, I for each cell that needs a relationship — leave blank where none.
- Enforce one Accountable per row.
- Ensure every package has at least one Responsible (or a clear path to assign one).
- Review with role holders so assignments are accepted, not only published.
- Align the RACI with the resource plan so Responsible parties are actually available.
- Control changes when scope or organisation changes.
Example fragment (simplified)
| Work package | Project manager | Design lead | Test lead | Ops manager | Sponsor |
|---|---|---|---|---|---|
| Requirements baseline | A | R | C | C | I |
| System design pack | I | A/R | C | C | I |
| UAT execution | I | C | R | A | I |
| Go-live decision | R (coordinate) | C | C | C | A |
In the UAT row, operations is Accountable for accepting that BAU can run the process; the test lead is Responsible for running the tests. That split is often missed when projects treat UAT as "IT-only."
Common RACI errors
| Error | What goes wrong | Correction |
|---|---|---|
| Two or more Accountables | Diffused ownership; each A assumes the other will decide | One A per work package; split the package if true dual ownership is needed |
| No Accountable | Work orphans; quality and deadlines drift | Assign a single A before baselining |
| A and R confused | Senior person listed as R for everything they cannot personally do | A owns outcome; R executes (A may also be R on small packages) |
| Everyone is C | Consultation paralysis; slow decisions | Restrict C to material expertise; move others to I |
| Missing BAU / supplier columns | External dependencies invisible | Include critical OBS external roles |
| RACI not resourced | Named R is 150% allocated | Reconcile with availability and smoothing/levelling |
| Set once, never updated | Matrix drifts from reality after reorganisation | Review at phase gates and major change |
| Too granular or too coarse | Unmaintainable noise, or useless slogans | Match WBS control level |
Scenario C — RACI conflict
A design package lists both the design lead and the project manager as A. When a standards conflict arises, each waits for the other. Correct practice: design lead is A for technical adequacy of the design pack; project manager is A for overall plan integration and may be I or C on the design package itself. Escalate only the cross-cutting trade-off (cost/time/quality) to the sponsor if needed.
Scenario D — consultation overload
Every work package marks eight stakeholders as C. Workshops cannot be scheduled; progress freezes. Rebuild the matrix: two genuine C roles for technical input, remaining stakeholders I via structured updates, and a single A empowered to decide within delegated limits.
Putting identification, OBS, and RACI together
For PMQ long responses on resource identification and accountability:
- Name resource types required by the activities (people, equipment, materials, facilities).
- Compare need vs availability with timing, not only totals.
- Use OBS to show the delivery organisation and gaps.
- Build or critique a RACI from WBS × OBS with one A per package.
- Link errors (dual A, unresourced R, ignored BAU) to schedule and risk impacts.
- Recommend firm commitments, re-planning, or escalation where availability is not real.
That chain satisfies LO21a–b and prepares the next section: once resources are identified and assigned, allocation, smoothing, and levelling keep the schedule feasible across linear and iterative life cycles.
What is the main purpose of an organisational breakdown structure (OBS) in relation to a RACI matrix?
Which RACI practice is correct?