'Why Are Manhole Covers Round?' Or Understanding Basic Coastal Design

摘要

The most complicated of design tools do have a basis in practical knowledge, and these rules of thumb are helpful, both in initially scoping a problem and solution set, but more importantly serving as the quality check for reasonableness after much more detailed theoretical study. As for "why are manhole covers round?," the answer lays in nothing theoretical, or structural, or even fabrication. The answer is lays in function. It is the only shape, that when turned in any direction, cannot be accidentally dropped through the hole on someone working below.