man holes / drain covers

[filanto]

why are some man hole covers round and some rectangular? is there any particular reason why they use one of the shapes to signify what is below

[ursula62]

Coal holes always had round covers, as this prevented the cover from falling down the hole.

[peanut]

the square holes are storm drains. The round ones can be for access to the connection point of underground wiring. the round ones are also used for access to cleanouts for the storm drains, this is where debris is caught from the drains. the pipes lead into and end in a big round concrete cylinder and they usually sit up a bit from the bottom so that the rocks and mud sink to the bottom. the dirty water flows in from one or more pipes, the debris falls in to the space below the pipes and the clean water flows back out through another pipe.

[sddsddean]

As an ex Civil Engineer who spent the best part of 10 years building roads, I can tell you there is no significance at all to the shape. It just comes down to the price and/or the specification of the client. Some councils like round, some like square. As to smaller ironwork, such as fire hydrants, they are usually, but not always, rectangular. They normally have letters on to denote what sort of valve or whatever is under them. eg FH =Fire Hydrant, SV = Stop Valve, WO = Wash Out. If you go to Disneyworld in Florida, all the manholes have a picture of Mickey Mouse on them. As I say, its just what the client wants!

[ianess]

Personally I think urula62 is 100% spot on.

You can't drop a round cover down a round hole.

In this area drain covers are disappearing at an alarming rate due to their scrap value......is this a national problem?  [Nothing whatsoever to do with their shape].

[qaswqasw]

it basically depends on the shape of the hole beneath it

[UmBongo]

it does make sence to have a round one so it wont fall down...