Sunk Effort - (Lesson learnt 1)

In behavioural science there is the “sunk cost fallacy” which has people throw good money after bad because of the investment already made. But this fallacy doesn’t just hold for monetary investments, it holds for most types of effort.

When starting a project from scratch I try and convince less experienced engineers to start with paper and longhand or a spreadsheet, if really necessary a very simple computer model and not immediately start a full 3D model based on the initial idea. 

Why?

A 3D model requires effort to build and, generally, isn’t that easy to make significant adjustments to. This means that once the issues / shortcomings of the initial model are identified there is a tendency to ‘tweak the model’ rather than have another look at the concept. If the work is done by a consultant it is both (lack of) time and the budget that can drive this and this can lead to a design that isn’t really ‘wrong’ but not necessarily optimal.

I was taught very early in my career to take a step back and optimise by one of my first bosses, Arie. Coming from a contractor's design office he had no qualms in rerunning a whole structure if he thought he saw a way to save even 1 pile. To explain why this was necessary to grumpy engineers and drafters he would then explain how many months (or years!) salary that pile represented. Models were simpler in those days but computers (a lot) slower so it could take some late hours of updating.

While the one pile might be considered ‘tweaking’ it went further. The picture below was of a permanent hoist for seawater pumps on an ‘offshore’ platform that would occasionally need to be removed for maintenance or repair. The pumps had started out smaller and lighter and the initial thought was to dismantle the suction tubes while hoisting. The structure started as a simple collection of steel profiles and a truss but, with the weight and height increasing, this became a monster that would need to be assembled on a small platform in the sea. Technically there was probably not much wrong with the design but when Arie saw it he was horrified and brought a new perspective to the table and we ended-up with a much simpler and easier to build structure.

So, when starting points change, loads, sizes, materials need amendment etc. don’t keep trying to make the same design work at any cost, take a step back and re-evaluate. Because some blindness to alternatives may occur once you have worked on a particular solution maybe also ask a colleague for her thoughts to make sure your concept is still sensible. If there is a time implication to adjust the design then maybe the boss or the client will need to weigh the impact of a change, be willing to discuss that. There are a lot of other things you can do for the cost of 1 pile!

Ps. The structure was part of the picture featured in my recent post and has since been dismantled. I’m clearly getting … mature.