Manholes | 24 Jul 2009

shabbir

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

nimesh

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

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

Great Answer

nimesh

Quote:

Originally Posted by rik625
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

Thanks!

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

shabbir Go4Expert Founder
24Jul2009,22:35	#1
	Why we have round manhole covers than rather than any other shapes? This is the case at least in India.

nimesh Invasive contributor
25Jul2009,01:00	#2
	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 Go4Expert Member
25Jul2009,04:33	#3
	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 Go4Expert Founder
25Jul2009,10:41	#4
	Great Answer

nimesh Invasive contributor
25Jul2009,20:55	#5
	Quote: Originally Posted by rik625 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?

Manholes | 24 Jul 2009

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rik625 Go4Expert Member
27Jul2009,07:55	#6
	Thanks! Well, yea in most of the places in US too those are circular in shape.

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