How do they bore under roads for gas lines and such?

[sixdogs]

Over the years I've seen a number of places where a company has bored under a road or other obstruction in order to install a gas or other utility line without disturbing the surface. Some borings seem to be a hundred or maybe 200 feet. Oddly, I've never driven by while they were actually doing it. Does anyone know how this is done?

How is the boring done, where does the dirt that is displaced go and how do they get the gas line or whatever to the other end?

 

[kennyd]

Two most common ways:

1) A "mole" that is driven with a large air compressor, no real directional control so it's only used for short distances:

HammerHead Mole(R) Pneumatic Piercing Tools Operations Training - YouTube


2) A directional boring machine:

Prime Drilling - Horizontal directional Drilling explained - YouTube

 

[EddieWalker]

I've had it done twice. First time was to bring water to my place. Second time was to bring in natural gas. I watched them do the water line.

First they dug down to the water main across the highway and exposed it all the way around. Then on my side of the road, they dug down to where they wanted the pipe to come out. The boring machine was set up inside the hole on the other side of the road down deep enough to drill straight and level to the trench on the other side. The drilling was simple enough. They had a water tank that drained the soil coming out of the hole. The pit the machine was in was dug so the water and mud would just drain out and away.

Once they got through to the other side, they pulled a cable through the hole when pulling back the drill pipe. Then they cut and bent the end of the metal sleeve pipe so it was shaped like a cone at the end. They welded it together and added a hook for the cable to the front of it. They used the hoe of the backhoe to pull the pipe through the hole. It just slid through there easily. Then the cut off the end of the pipe that they has spent so much time welding up and slide the water pipe through the metal sleeve.

They dug the trench for the pipe onto my land, and ran the pipe to that point and ended it with a valve. I ran the pipe the rest of the way to my house.

 

[Deere Dude]

Good question. I still don't understand how drilling something horizontal can change course direction in the middle of the run?

Or even with oil drilling in the ocean. How can it go straight down for 5000' then turn and go horizontal.

 

[k0ua]

Good question. I still don't understand how drilling something horizontal can change course direction in the middle of the run?

Or even with oil drilling in the ocean. How can it go straight down for 5000' then turn and go horizontal.

This may help some.

Directional drilling - Wikipedia, the free encyclopedia

 

[kennyd]

Good question. I still don't understand how drilling something horizontal can change course direction in the middle of the run?

Or even with oil drilling in the ocean. How can it go straight down for 5000' then turn and go horizontal.

Simple way, used for most utilities since the runs are shorter, horizontal, not generally to deep, and it cost's less.
horizontal direction drilling rig for underground cable - YouTube

The shape of the head determines the direction, when its turning it goes straight-when its just pushed it starts to change the direction path.

Complicated way:
Horizontal Directional Drilling / Boring (HDD): How the Drill Bit is Steered - YouTube

 

[teg]

They are drilling a 54" sewer line under roadways near our house. The most extreme was going across a four lane road, under a restaurant, and in to the next business back parking lot.

They dig a hole (estimate) 30' wide x 60' long x 20'?? feet down (I never got close to see in the hole) on both sides of the road. They have lots of specialized equipment that get lowered down into the hole... Boring machine with 48" (most likely larger) drill bits.

They bore, remove dirt, and lay pipe in the "tunnel".... big bucks for this job...

 

[teg]

Will be interesting to see the mess that's left in the holes after Matthew the hurricane. They are drilling this 54" pipe right along side Crabtree creek,, which is the main creek through town, last check, it peaked at 22' (6' above flood stage).

 

[dodge man]

For larger bores they drop a rig in the hole that runs on rail. These rails are roughly 20 feet long. Then a machine gets dropped in the hole with an auger head that is powered by a drive shaft. The ones I've seen include an engine and every thing on the boring rig. Usually a large steel casing pipe is pushed in along with the auger head. The rig goes all the way to the end of the rails, drills the length of the rails, backs up to the far end again but the auger head is left in place. Then another length of drive shaft is installed, another piece of casing pipe welded to the end of the first, and the process repeated. After you get the casing under the road, you the pull the rig out of the hole then slide your sewer pipe or water main into it and your done.

The advantage to this it can do large bores. If something goes wrong with the pipe later, you just dig up the ends of the casing, pull the old pipe out and slip in new. The bad part is you can't steer the pipe and it's slow process compared to directional boring.

 

[tallyho8]

Hydro tunneling is the most popular method in our area. They go under slabs, road, railroads, parking lots, etc.

The truck has a water supply with a high pressure jet and it vacuums the loose dirt out into their tank then goes and dumps it. They can also pump sand back into the hole after or pump sand under homes that have low spots under them.

I am lucky enough to have some low-lying land that I rent out to a hydro tunneler. Besides collecting rent i am getting my land filled for free.