Why is a manhole cover round?

Question

please help me plz.........

Answer 1

The actual reason is that it is the only shape that will not allow for the lid to fall into the hole no matter how you rotate it.

Answer 2

It maintains equal strength at all points. Making cracks less likely.

Answer 3

Hmmm...

1. Round manhole cover is more easy to move. If you are alone, you could roll the cover away like a wheel. You had to lift it the whole way if the manhole is square or rectangular.

2. Round manhole cover is easy to place back. You don't have to lift and rotate the cover to make it rest properly on the hole. Not the same for other shapes.

3. Round manhole cover could not fall into its hole. A square manhole could, just place one of side of the cover along the diagonal of the hole. You would then have a bad time lifting it up, or worse you may hit someone on the head.

Answer 4

Because the hole in the ground is round.

Are you in Kindergarten, or the first grade now?!

Answer 5

Real reason-- a round circle won't fall in the hole. Plus the pipes are round, so why not.

Answer 6

The god of thunder is correct, however there are some that are other shapes, not many, but some.

Answer 7

Manhole covers are usually round , especially the ones used on streets.   They are round because they are easiest to replace and that shape is also the easiest for a man to get into and  out of. The reason that they don't fall into the round hole is because the cover sits on a flange in the hole .

Answer 8

Hmmm. I think because a circle uses up less area than a rectangle or square for example which = less metal use and so it is less expensive to make round manhole covers.

Answer 9

Manhole covers are round, heavy and also have a sort of pointed pyramid of metal on the underside for one main reason.  As sewers age, they leak. Older sewers can overflow during rain storms. When this happens the water can, and does, lift the manhole cover and water leaks out evenly on all sides( kind of like a circlular fountain.)  As the water subsides the manhole cover will comes down right over the hole again.  This means workers don't have to go find and replace covers after every rain.  

It's kind of cool. As an engineer, I've seen it happen a bunch of times.

This is why all standard manhole covers are round. (Yes and thunder is right too. It won't fall in.)

Answer 10

A man hole cover is round because a cricle can't fall down its own hole. Think about it. if it were  a square, it could fall down the hole and hit a worker in the head. because it is round, it cant do that.

Answer 11

Thunder is correct.  I would add that some covers to water and electrical vaults are rectangular but those are hinged and attached and can't come loose.