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shabbir 24Jul2009 22:35

Manholes | 24 Jul 2009
 
Why we have round manhole covers than rather than any other shapes? This is the case at least in India.

nimesh 25Jul2009 01:00

Re: Manholes | 24 Jul 2009
 
well if you have asked it here, then there might be some logic behind it.
How's it in other countries?

And nowadays I think they have started making the rectangular ones too.

rik625 25Jul2009 04:33

Re: Manholes | 24 Jul 2009
 
Reasons for the shape include:

#A round manhole cover cannot fall through its circular opening, whereas a square manhole cover may fall in if it were inserted diagonally in the aperture (A Reuleaux triangle or other curve of constant width would also serve this purpose, but round covers are much easier to manufacture.)
#Round tubes are the strongest and most material-efficient shape against the compression of the earth around them, and so it is natural that the cover of a round tube assume a circular shape.
#The bearing surfaces of manhole frames and covers are machined to assure flatness and prevent them from becoming dislodged by traffic. Round castings are much easier to machine using horizontal boring mills.
#Circular covers do not need to be rotated to align them when covering a circular manhole.
#Human beings have a roughly circular cross-section.
#A round manhole cover can be more easily moved by being rolled.
#It's easier to dig a circular hole.
#Tradition
#Supply. Most manhole covers are made by a few large companies. A different shape would have to be custom made

shabbir 25Jul2009 10:41

Re: Manholes | 24 Jul 2009
 
Great Answer :D

nimesh 25Jul2009 20:55

Re: Manholes | 24 Jul 2009
 
Quote:

Originally Posted by rik625 (Post 53460)
Reasons for the shape include:

#A round manhole cover cannot fall through its circular opening, whereas a square manhole cover may fall in if it were inserted diagonally in the aperture (A Reuleaux triangle or other curve of constant width would also serve this purpose, but round covers are much easier to manufacture.)
#Round tubes are the strongest and most material-efficient shape against the compression of the earth around them, and so it is natural that the cover of a round tube assume a circular shape.
#The bearing surfaces of manhole frames and covers are machined to assure flatness and prevent them from becoming dislodged by traffic. Round castings are much easier to machine using horizontal boring mills.
#Circular covers do not need to be rotated to align them when covering a circular manhole.
#Human beings have a roughly circular cross-section.
#A round manhole cover can be more easily moved by being rolled.
#It's easier to dig a circular hole.
#Tradition
#Supply. Most manhole covers are made by a few large companies. A different shape would have to be custom made

nice answer rik :)

So In US also, they are round?

rik625 27Jul2009 07:55

Re: Manholes | 24 Jul 2009
 
Thanks!

Well, yea in most of the places in US too those are circular in shape.


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