From: Otis Wright
Similar HDD setups are used to lay gas pipe up to 50 inches or so --- possibly larger --- but this is the largest I have first hand knowledge of. So, laying underground medium and low voltage lines should be feasible.
What they do around here is trench alongside the roads & bury semi-rigid plastic tubing - similar to what Home Depot sells for foundation drains, but without the holes in the side. Not black either.
When they get to a location where they have to cross under a road they bring out that horizontal drilling machine. It's got some kind of control mechanism so they can make it loop back up once it gets to the far side of the road. Apparently they have some kind of maps that show where the existing underground utilities are located so that they don't drill through them.
I've seen the whole process in action. The first thing you see is the same guys who find your utilities at home when you've got to replace a water line or get new gas service. If you come down the same stretch of road a few days later you'll see the end of a blue or orange plastic tube (or several) sticking up from the ground and a little farther down the road the crew will be trenching & the trenching machine will have several big spools of the plastic tubing on the back. Usually they're already drilling under the next few intersections so the hole under the road will already be in place by the time the trench gets there. Later you'll see more plastic tube ends sticking up out of the ground.
Once the trenching & drilling is done the crews threading the fiber-optic cables through the plastic pipes take over and in a few days you'll see the junction boxes sitting where the ends of the plastic pipes used to be.
It really ain't that hard to repair since all the splices & such are made on the surface in those junction boxes. The only time they ever have to make repairs under ground is when some fool with a back-hoe starts digging without consulting the utility locators.
And in that case there's no reason to charge the utility customers for the cost of repairs. Let the idiot who broke pay for fixing it.
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