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Eric Graves

Aerospace and mechanical engineer turned NPD systems engineer, Eric spends his time engineering better product develop systems, using PLAYBOOK as his tool of choice!

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Architectural Runway and WSJF

Eric Graves- 10/24/17 03:33 PM

What is an architectural runway?

Designing a new product with an architectural runway means supporting the business' ability to "land" new features in the future with limited additional effort. But is it worth it? WSJF can help answer this question...

Architectural runway and WSJF

Building and maintaining runway adds work and increases duration up-front, but reduces work, and allows for more improvements in the long run (for example via increased sales volume or price). The questions we need to answer are: Is building an architectural runway worth the investment, and if so, when should we do it?

Answering these questions is where cost of delay (COD) and WSJF can help. In fact, WSJF can answer both questions.

How do you calculate the COD of an architectural runway effort?

The COD of building an architectural runway is the sum of the COD of all of the features it will enable and will be worth the time to build once the architecture is in place. Most of these features are usually unknown in advance, so it is hard to quantify precisely, but we can make an educated estimate.

For example, we could assume the architectural runway will enable ~20 features with average COD of $X each. It may enable ~30, but only 20 will be worth the time to build even after the architecture is improved.

Some people don’t like to use fuzzy estimates, but there are so many unknowns in product development that fuzzy estimates are often all we have to go on, and aren't usually that far off if we base them on past experience.

The WSJF calculation for architectural runway projects is similar to that of research projects or feasibility studies." The main difference is that in feasibility studies and research projects there is a probability of success. For example, that the information you generate will provide you with needed information to progress additional products/features, rather than leave you at dead end. I suppose the probability is still there for some architectural improvements, but it’s usually a lot higher or close enough to 100% to just ignore it.

How do you calculate duration?

Duration for the WSJF score is a little more complicated. We generally will release the enabled features/products over the course of weeks, months, or even years, with the most valuable ones first. But the duration isn't the time from when you release the first new feature until you release the last new feature – it is somewhere in the middle. A weighted average should be used. It is like calculating the center of gravity in this example where the COD is the mass and the duration is the length from the ‘datum’ (which is on the day the feasibility study/architectural improvement begins).

For example, if a 2-month feasibility study/architectural improvement enables 2 features: the first one with COD of 10K and duration of 1 month, and then a second one with a COD of 5K and duration of ½ month, the weighted average duration for the WSJF calculation is:


(10*(2+1) + 5*(2+1+.5))/(15) = 47.5/15 = 3.17 months

Note, it is the same as the duration of the feasibility study plus the weighted average duration of the product releases after that point:

2 + (10*1 + 5*(1+.5))/15  = 2+ 17.5/15 = 2+ 1.17 = 3.17 months

Once we have calculated the WSJF score (total COD / weighted duration) for our architectural runway effort, we can see what priority building an architectural runway would take vis-a-vis our other options.

If the WSJF score is high, it would make sense to do it sooner. Alternatively, if the score is low, we might never choose to do it.

Let us know your thoughts on this topic....


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