A great way to understand the engineer’s interest in living life far from those risky edges is through the geotechnical world, otherwise known as playing in the dirt. When an engineer has to determine whether a soil will fail under the weight of a building, the engineer uses an equation – no surprise there. I won’t go into all the details here for fear of alienating the non-engineers (or putting them to sleep), but in simple terms the engineer want to assure that:

F < S

where, F = the force of the building

and S = Strength of the soil or the amount of Force the soil can withstand before failing

But no one wants S to be just barely more than F. Maybe we measured the forces wrong, or an extra force ends up on it, or our estimation of the strength of the soil may be off, or…. a lot of other things.

My first class in geotechnical engineering helped me see the risk-averse side of engineering. Use an equation with numerous variables which are mostly Greek letters, so you know they must be important. This involved look-up tables and various calculations to arrive at a number for both sides of the equation. Then, to make sure it is safe, multiply the force by 3. Yes, engineers want the strength, after all the complicated equations, to be 3 times stronger than what we calculate may be the force it needs to withstand.

This is how engineers live life. Make all the calculations. Then multiply by a Factor of Safety of 3. It explains a lot.