Balanced readiness: keep your readiness levels in step

Teams usually push hardest on the risk they understand best. Engineers mature the technology, and manufacturing, integration, users and the market wait their turn. The product looks ready on its TRL, but it is only as ready as its weakest dimension.

Retiring one type of risk much faster than the others doesn't save time. It moves the other risks later, to where they cost the most to fix.

What the MacLeamy curve teaches

In 2004 the architect Patrick MacLeamy drew a simple chart for building design. As a project moves forward, the ability to change it falls and the cost of each change rises. Traditional projects do most of their design work late, after change has become expensive. MacLeamy argued for moving that effort earlier, while decisions are still cheap.

The same curve applies to product readiness. Manufacturing, integration, human factors and commercial questions are cheapest to answer while the design is still moving. If they lag behind the technology, they come back after the design has frozen, as rework.

The evidence

• The US Government Accountability Office found that maturing technology before it enters product development is one of the strongest predictors of success. It recommends at least TRL 6, and preferably TRL 7, before development starts. Programmes that began with components at TRL 2 to 5 saw cost growth of 88% to 101%.
• NASA describes TRL 6 as essential but not sufficient. In its examples, technologies that had been proven in flight stalled because maintainability, manufacturing, integration or certification were considered too late. It calls the result the “valley of unused technologies”.
• The US Department of Defense designed MRL to be roughly congruent with TRL, and sets manufacturing expectations at each milestone. It expects MRL 4 at Milestone A, MRL 8 (pilot line demonstrated) before low-rate production, and MRL 9 before full-rate production.

Balanced vs lopsided

Two products, each scored on five scales. The dashed line is the TRL. The lopsided product looks further ahead on technology, but has more unretired risk.

Five common imbalances

How to keep readiness aligned

1. Score every scale at every review, not just TRL. A scale nobody scores is a risk nobody owns.
2. Set gate thresholds for each scale, for example TRL 6, MRL 6, IRL 5 and HRL 5 to enter development. Your thresholds will depend on your sector and funder.
3. Flag any scale that trails the leading one by two or more levels. This is our rule of thumb, and a gap that size is worth a conversation at the next review.
4. Let the weakest scale set the pace. Put effort into the lagging dimension before pushing the leading one further.
5. Front-load the cheap questions. A quick cost model, an interface list or an hour with real users at TRL 4 can save months at TRL 7.
6. Watch the trend, not just the snapshot. A gap that widens at each review, or a scale that hasn't moved in two quarters, is a leading indicator that a scale is falling out of step.
7. Turn every gap into an action with an owner and a date, or record it as an accepted risk with a reason, so balance becomes part of the plan.

Frequently asked questions

Sources

• US GAO, Technology Readiness Assessment Guide (GAO-20-48G)
• NASA, Total Technology Readiness Level (AIAA paper, c. 2021)
• Manufacturing readiness levels and DoD milestones
• The MacLeamy curves explained

The scale guides

• Technology readiness levels (TRL 1–9)
• Manufacturing readiness levels (MRL 1–10)
• Integration readiness levels (IRL 1–9)
• Commercial readiness index (CRI 1–6) and adoption readiness levels (ARL)
• Human readiness levels (HRL 1–9)