Organizational Breakdown Structure & RAM

What the OBS and RAM are

The previous lesson gave costs an address (code of accounts). This one gives work an owner. Together they answer the two questions cost control depends on: what is the cost? and who is accountable for it? The RAM is where those two structures formally meet.

The control account

Where a branch of the WBS meets a unit of the OBS, you get the single most important concept in project controls:

The control account is the cell in the RAM grid: this work (WBS) × this owner (OBS), with a budget attached. It's where earned value is measured (Module 4C), where variances are analyzed (Module 4B), and where accountability lives. Everything in project controls rolls up from — or drills down to — control accounts.

Reading a responsibility assignment matrix

The RAM is typically a simple, powerful grid: WBS elements down one axis, OBS units across the other, with responsibility marked at the intersections.

Using OBS, RAM & control accounts

Build the OBS alongside the WBS at setup, map them in the RAM so every work element has one owner, and define control accounts at the intersections, right-sized for management. These structures, with the code of accounts (Lesson 2), are what the controls plan (Lesson 1) puts in place — and what everything in Modules 4B and 4C measures against.

Nine things to remember

1. The OBS breaks down the project organization — who is responsible — mirroring the WBS.
2. The RAM maps work (WBS) to responsibility (OBS) — every element gets one owner.
3. Code of accounts = cost address; OBS/RAM = work owner — the two questions control depends on.
4. "Everyone is responsible" means no one is — the RAM makes ownership explicit and exhaustive.
5. The control account is where scope, budget, schedule & responsibility intersect.
6. The CA is the basic unit at which performance is planned and measured (earned value, variance).
7. Right-size control accounts — meaningful to one manager, small enough to reveal problems.
8. The RAM is a coverage check — no unowned scope, no double-owned scope.
9. WBS + code of accounts + OBS + control accounts make a project genuinely controllable.