Life's Great Mysteries - Why are manholes round?

This is a relatively easy one. Let's think about this. People aren’t hobbits—we don’t put round doors on our houses. We don’t put round doors on schools. Gas stations, courthouses, factories, and Walmart stores? Nope, no round doors there. All rectangular. Even the hatches on airplanes and submarines are mostly rectangular, although they do have rounded corners. But a manhole, and the corresponding manhole cover—round as a moon pie. What’s up with that?

As it turns out, there are several reasons. As the saying goes, “safety first.” So, perhaps the most important reason for round manholes is that the covers cannot fall through the hole and bonk someone (presumably a “man”) on the head. A rectangular or a square cover could be turned in such a way as to fall through the hole. And if you’ve never picked up a manhole cover, they are heavy!

Here’s another reason. Round covers are easier to fit onto the hole. They don’t have to be turned a certain way, as a square cover would. They’re heavy, remember, so no one wants to turn a manhole cover this way and that to get it to fit.

And… you can’t cut yourself on the corner of a manhole cover if it ain’t got no corners (safety first, remember?).

And finally… as if this weren’t enough reasons, round manhole covers are easier to move from one place to another. Instead of having two people carry one, a single person can simply roll it.

Photo Credits:
- Manhole cover - DepositPhotos