Good Enough Design

While studying Engineering, the majority of students are taught rules, whether rules of thumb or hard and fast rules, most of the life of an engineering student is governed by absolutes in the form of equations, tables, constants, methods, design software and a lot of straight lines, (or absolute curves). On top of this, there is almost always a “right” answer, while every other answer is substandard, whether by failing to optimise a solution or because it would create something downright dangerous.

The shock for most engineers when they reach the real world is that outside of the design software and air conditioned office, there are no straight lines and the absolutes are blurred by constraints, whether financial, spacial or material. This is where engineering and science depart, the engineer is to find a workable solution given the absolutes and the constraints, but I find that there are many engineers (and people who have expectations of engineers), who just don’t get it.

I started my engineering degree in the Australian Army, studying at the Australian Defence Force Academy, but unlike most engineering students, Field Engineers in the Army don’t have the expectation of perfection or the luxury of a design team equipped with world class design software, and the attitude of simplicity and functional design take designs out of iterative processes, or inane details, and into rapid construction. Sometimes good enough is enough, and any additional effort is wasted.

Now this doesn’t apply when life-safety design is encountered, or for novel construction techniques, or architecturally designed structures that look like they almost float. But for building roads, sewers, water systems, lighting, retaining walls, sidewalks and many of the other civil engineering items that are part of my bread and butter, good enough is often enough. Part of being an engineer is knowing where the risk lies and designing for it in the simplest manner. Doing this in a consistent and competent manner is at the core of engineering.

Published by Mike Thomas

Mike Thomas P.Eng. ENV SP, is the author of and Director of Engineering at the City of Revelstoke in the Interior of British Columbia, Canada.

4 replies on “Good Enough Design”

  1. This is something I talk about a lot at the Regional District at which I work. I would love to know–I think it is absolutely critical information for times of constraint–what are the rules of thumb you use to judge when a design is Good Enough? And, feel free to use my motto–Good Enough is the New Great.

    1. @Ruben – complexity and lifecycle cost are my main concerns, and risk of failure and the cost of response are probably closely related to either of these.

      Rules of thumb are tough, I’ll give it some consideration though.

  2. We should probably have a phone call one of these days, or maybe a coffee if you get down to the coast.

    Complexity is one of the things I often think about, though sadly I am merely advocating for it to be considered, I don’t have any power to incorporate it into planning or engineering decisions.

    In typical bureaucratic butt-covering it is always safer to do a study than to do work, but Tainter’s work (and our actual experience) should tell us there is a point beyond which more study reduces the absolute payback. So what do you do? A study to tell you when to stop studying? The closest rule of thumb I can come to on this is the 80-20 rule.

  3. nice article Mike – I believe there’s lots of grey in engineering – really with unlimited funds ANYTHING is possible, but consideration, cost, and realism are really the constraints. Love the blog BTW!

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