eli5 why are manhole covers in the middle of the road and not on the sidewalk?

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eli5 why are manhole covers in the middle of the road and not on the sidewalk?

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19 Answers

Anonymous 0 Comments

Because they are used to access utilities like sewers or gas lines, and those are located in the middle of the road.

They aren’t ALWAYS in the middle of the road, sometimes they might be under the sidewalk. But a lot of the time they are in the middle of the road because this keeps them an equal distance from the houses on each side of the road which all need to use those utilities. Also, these are publicly owned services which city workers may need to access or even dig up for repairs. It is best if they don’t need to go onto or damage people’s private property to do this, and a sewer under a sidewalk for example would either be very close or actually overlap with people’s buildings or front yards.

Anonymous 0 Comments

There has to be a better way. Why not put them under the buildings ? Obviously doing that retroactively would be extremely difficult and costly but when designing new cities why wouldn’t the utilities be placed in line underneath the properties ? Then there could be access points on the sidewalks and of course the utilities would have to cross streets but they would be under every single part of every single street, just part of one spot of streets like a crosswalk

Anonymous 0 Comments

In the UK, they are both in the road and on the pavement (sidewalk for you silly sausages across the pond)

Anonymous 0 Comments

Some might have been initially on the side of the road, but if the road had been widened, altered, or lanes added, they would no longer be on the side of the road.

Also, there are several different utilities trying to use the same right-of-way. You could have water, sewer, drainage, electrical, and communication all having their own infrastructure in the ground. All would have their own manholes for access.

Also, in larger cities or communities, if a conduit system filled up then extra manhole systems would be added in whatever space was available.

And lastly, it depends on what is under the ground. Utilities will not want to blast through bedrock or ledge and will prefer to place their infrastructure in soil.

Anonymous 0 Comments

I’ll do you one better, WHY are they called manholes? XD

Anonymous 0 Comments

Manholes and valve boxes are located directly above the pipes that they access. As others have mentioned, there are often multiple utilities running parallel with each other down the road. Many municipalities require certain separations between different utilities (for example a water line may need to be 3 or more feet from a sewer line). This is to protect against contamination in the event of a pipe leaking/breaking and to allow room to work around them.

Another big consideration is repair cost. Pipes need to be repaired, and replacing a bit of asphalt in the road is a lot cheaper than replacing concrete sidewalk.

As an example a current project I’m working on has a storm drain line, waterline, recycled waterline, gravity sewer line, force main sewer line (pumped sewage to get it uphill), gas line, fiber optic conduit, and underground electric. These all have to run down the road with different separation requirements from each other.

Anonymous 0 Comments

All the other reasons and also this. Sidewalks are still a part of the transportation infrastructure and manholes do less harm in the road than the sidewalk. If you’re working on a manhole you’d have to block the whole sidewalk, whereas the road is wide enough a car can go around it. A car can easily roll over a manhole, but could a manual wheelchair? What about someone using a walker? Even someone just with something else on their mind could easily trip on one, whereas it’s doing almost no harm in the road.

Anonymous 0 Comments

Why aren’t they all in a nice air conditioned space back at hq??

Anonymous 0 Comments

It’s a heck of a lot cheaper to rip up a road for major repairs than it is to rip up buildings.

Anonymous 0 Comments

sometimes they are on the sidewalk. It’s less about being “in the middle of the road” and more about being where the underground pipes are.