Why are manholes circular in shape?

Question

I mean, why cant be square or rectangular in shape?

Answer 1

I will surmise that because the " riser ".., the " Donut".., and all the pipes that the manhole gives access to.., are round.
Besides, when the cover needs to be lifted, a round one will allow easier removal than any other shape.
When you put any other shape on edge, the circle affords the least perimeter area in contact with the hole.., thus allowing the easiest removal.

Answer 2

Hey some manholes are also in square and rectangular shapes
A maintenance hole or manhole is the top opening to an underground vault used to house an access point for making connections or performing maintenance on underground and buried public utility and other services including sewers, telephone, electricity, storm drains and gas. It is protected by a maintenance cover, a (usually metal) plug designed to prevent accidental or unauthorized access to the manhole. The reason most manhole covers are circular is that the round cover cannot fall into its own hole (the maximum diagonal distance is the same as the diameter, unlike rectangular covers where the diagonal distance is greater than the maximum length or width).

Manholes are generally found in urban areas, in streets and occasionally under sidewalks.

In rural and undeveloped areas, services such as telephone and electric may be carried on pylons rather than underground.

Answer 3

Why Manholes Are Round

Answer 4

All diaginal of a circle is equal. So, the covers will never drop down into the manhole. But in case of squares or rectagles the sides are smaller than the diagonals so there would a possiblity of drpping down the cover into the manhole if they are shaped as rectangular or squares.

Answer 5

This Site Might Help You.

RE:
Why are manholes circular in shape?
I mean, why cant be square or rectangular in shape?

Answer 6

Manholes are round to keep the lid from falling through.

On an angle, a square shape can fall in, should something arise.

Answer 7

Manholes are circular because no matter which way you turn the cover, it will not fall through the hole. A square or rectangular cover if turned at an angle to square or rectangle, can fall through the manhole.

Answer 8

They could also be rectangular / triangular or any shape.. However, being circular ensure that the cover doesn't accidentally fall inside & create problem.
Further it is easy to shift them from one place to other by simply rolling carefully .
A circular structure also known to bear / districute load in a balance manner .

Answer 9

i would assume that it would be to distribute the presure evenly across the man hole cover when vehicles, etc drove over them, also, a square man hole, a corner could turn up, puncture a tyre? A round manhole cover can be placed in anyway and still fit, any other shape, unless perfect would only go in a certain way.

Answer 10

Very good question. Making the lid round ensures that it can't fall into the hole. A square lid on its side would fall into the manhole.