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You can make a cover of any shape you want that won't fall in. It depends on how much the cover overlaps the hole. Even with a round cover, you can't have zero
by hobbs 19y ago
You can make a cover of any shape you want that won't fall in. It depends on how much the cover overlaps the hole. Even with a round cover, you can't have zero overlap or else the cover would fall in.
Now back to the correct answer, which is because the manholes are round - that begs the question of why manholes are round. It's probably a matter of equally distributing the sideways forces from the dirt plus a matter of being able to manufacture round tubes more easily than, say, square tubes or hexagonal tubes.
- Frocer 19y agoIt won't be a cover unless it's slightly larger than the hole wouldn't it? :)
- TrevorJ 19y agoActually, no, a square cover would have to have a much wider flange in order to ensure that it could not fall in . (rotated 45 degrees in relation to the whole and tipped up, a square cover would fall in)