It's roughly 5-7 times as expensive per km to bury the cables. It's mainly a cost issue.

It makes sense in dense areas, it does not make sense everywhere. Critical infrastructure has backup power anyway because digging does not solve all reliability issues.

sweden hasn't had residential power lines on poles since like the 70's. when i visited north america in 2008 i was shocked by the aerial rats' nests everywhere.

They are. In developed countries.

Don't make the mistake of looking at one region and generalising to a universal. Where are you looking at?

Here in Switzerland practically everything <1kV is buried.
For high voltage lines they have only built one section to experiment so far. It's pretty expensive, heats the ground a bit and blocks water with all the concrete, so it's not so clear if it's a good choice for agriculture happening above.

I've wondered a lot why they don't bury more infrastructure in hurricane regions in the US for example.

Because it's much harder to bury things above ground.

Almost anything infrastructure related, however it exists is probably the most efficient cost/maintenance ratio for that area. That is basically the only requirement for the engineers in charge of designing that kind of shit.

Unless you're the Texas power grid. Then it's literally the cheapest possible way to still be able to bill people for it.

My city sits on a filled in swamp.

There’s a pragmatic reason too. Power lines and transformers need constant maintenance. When the line fails somewhere, it’s easier to access when you don’t have to dig, and also less disruptive.

Also, they’re up high because people in general are dumb af and will fuck with them if they’re within reach.

physics. cost.

lived a lot of places, some of which (like here in PNW) have neighborhood buried cables. It's lovely, and hella reliable. We don't lose power in windstorms or floods or snow.

It is expensive. And not appropriate for all places - for example, places with high water tables won't be able to do it, like Louisiana - you can't keep the water out year round even with a billion pumps. Also hard to do in places with bedrock near the surface for expense reasons.

Harder to maintain if it is underground.

Maintenance, modification, assessment, and initial installation are all more difficult. And yes that means more expensive, and yes the cost difference is significant. It is more resource and personnel intense to work underground lines than overhead.

When it comes to damage from weather, while underground lines can be slightly more resilient they are much, much more of a pain to assess and and fix. A good line crew can put up a new pole in about an hour. It takes a lot longer to run underground digging equipment.

In some places underground lines are run, of course, because for various reasons the associated downsides are deemed worth it. However when you're looking at a whole infrastructure, you want easy to service, fast to install, and cost efficient.

Cost, difficulty, and harder to maintaince. Want to add new coax cable? Sure toss it up. New housing being? Split it. Fiber, yep throw where the coax is. Etc. (its still high voltage, so regulations for safety obviaouly play a role here too).

Underground? Is there rock too hard to drill there? A gas line? Did we just cut an active internet line or just some junk? Tree roots? Will it containate a water table? Will it shift and break the line here? Great we have conduit, is it broken? Leakage? Big enough to handle a high gauge for an upgrade?

i say this as man in love with a good tunnel and conduit. Trust me when i say, yes we ought to do it in general, but also yes is a pain in the ass.

You don't pay for all the space between poles. Its also cheaper ad quicker to stand a pole than to build a manhole.

It would be better for everyone if was all underground. It is purely cost with a smidgen of time efficiency.

They generally are, in rich countries. In poorer countries with less developed infrastructure you can still commonly find them.

Bit unsightly too

i actually love them, aesthetically.

i think they're cheaper to replace/repair in earthquake prone regions

ALSO if you're in a snowy remote region, serial killers LOVE to snip these so they can "pick people off" one-by-one. This might seem detrimental to the local economy, by virtue of depleting the workforce, but serial killers are great for local tourism once they're put away.

Money.

I work in different utility but the principal is the same. It costs roughly 10x as much to bury cables in the ground than it does to put them in the air on poles.

It tends to make sense in dense urban environments or where there's other factors but for almost all rural and suburban settings the costs to dig in underground cables, ducting, access structures and the associated safety concerns, plus the increased costs to access and repair, far outweigh the possible costs of running cables overhead, even though they're more susceptible to damage.

edit:sp

One reason for my region: overhead lines on wooden poles will better withstand an earthquake and will be quicker to rebuild after a major disaster. Stuff underground will get all shifted around or filled with water and mud.

Go dig a trench the length of every city street in the world, and come back and tell me how easy that was.

Would you rather spend $100 for a 5% chance of losing power for 4-8 hours per year, or spend $10,000 dollars for a .1% chance of losing power for a minimum of 2 days?

Where I live, all the power, except major cross-country transmission, is underground.

You do find more minor transmission lines out where it gets rural, right down to telegraph-style wooden poles, but you'll pretty much never see it in cities or suburbs. (Wooden telephone poles are a different matter).

The only advantage of power-by-pole is ease of repair. Once it's underground, it has to share trunking with the other utilities in the area, and I'm pretty sure the number of times a road needs to be dug up varies as the square of the number of utilities under it.

But at least it's relatively safe under there when the road isn't being dug up for the fourth time in a year.

When my mom got fiber internet, they had to dig a trench through everyone’s front yard in the neighborhood. They managed to destroy one of her Christmas yard decorations.

When I got fiber internet, a dude in a truck ran it from a pole across the street in like two hours.

Probably harder to maintain easier fixes in colder areas where the ground freezes for half a year.

Let me reverse the question

Why do power cables need to be buried in non dense urban area?

Yes it will make it a bit ugly, but so what?. It's not like it being ugly will do anything anyway. It's not like being a bit ugly is a very annoying thing unlike when there a trash heap and it smells bad.

I think we should just keep it up there for sub-urban and rural areas, and invest the saved money on other things.

Also, im from developing country so my perspective is bit different for this topic.

AC lines would get large capacitance losses being buried vs. overhead. ElectroBOOM explains why in his vid about high-voltage DC lines starting at this point in the vid.

Granted this is at high voltages in the five-digit range and beyond, and I'm not sure how much that would matter at 240V split-phase that homes typically get in North America*, but that's a technical reason why power lines are still overhead regardless; it's more efficient and with less capacitance losses to have overhead power lines spaced far apart than to bury them.

*Yes, really, I meant what I said, North American homes still get 240V, but it's split down the middle; 120V circuits for things like lighting and such, and normal devices that you plug into a NEMA-5 outlet such as portable space heaters, use a single hot line and a neutral line while 240V circuits for high-powered appliances like clothes dryers, ovens, HVAC systems, and things of that nature, use both hot lines, and optionally neutral in addition for things in, say, an oven or a dryer that only need 120V such as lighting, while the heating elements need 240V in those applications.