Mexstan

Was just reading the news story about the arrest of one of the drug kingpins and how he was responsible for digging many of the tunnels between Mexico and the states. Over the years I have read many stories of tunnels being dug from one house to another etc and have always had a question.
My question is, how do these guys know the direction and distance so precisely that they can come up at a designated place? In the case of a tunnel under a border, it is of course impossible to go on the surface to measure distance etc, so how do they know when to stop digging horizontally and go vertical? Over a long distance a degree or two off course would bring the tunnel up next to the house or a house or two over. So how do they do it?

Geico266

A compass would work underground. Distance could be measured on the surface with a range finder, underground with a string. Dig the correct distance horizonally and head up.

My question is what do they do with all the dirt?

hotdram

You planning a small project Stan?

~Rob

CSAGrey1

GPS maping and old fashioned figuring.

Geico266

GPS would not work underground. It needs to "communicate" the sats., but you could use it to locate on the surface.

SoTexRattler

A simple surveying LASER! and a competent surveyor...
Keep digging in the direction of the little red dot...
Distance is easily measured by optical means or a good surveyor could do it with his tape.
I always wondered about the dirt too...

Sounds like the govt needs to regularly contract some seismograph shaker trucks to drive up and down the border thumping the heck out of that area... Then, for those pesky, recurring tunnels in tough neighborhoods, use a heavy charge of explosives to REALLY shake things up underground... Or even use a FAE charge which would take care of the structures at BOTH ends of the tunnel.

K.

Begle1

Spoken immediately after drug smugglers dig up through the lingerie department at WalMart:

"Pedro, did you bump that laser again?"


Considering that the Dark Ages Euroeans dug tunnels under castles to collapse the walls, I wouldn't think lasers and technology are really needed...

Mexstan

No, I don't have any projects planned - yet.
Wonderered about the dirt also, but forgot to mention that.
I thought about a laser, but that would be hard to use across a border. Wouldn't that red dot give things away? In any case, lasers are relatively new, what did the old time tunnel diggers use?
Also, it would not be practical to use a tape if you can't measure on the surface first. Remember, the destination site (point B) is one that you may not have access to from the point A.
So how do you measure from point A to point B underground if you do not have access to point B on the surface?

HappyGA

can not see red dot underground from the surface

displacedtexan

Measure on maps? I have no practical experience on this subject, so it's just a guess.

Hoss

You guess.

XLR8R

LMAF!

Timmay2

Ask your family members who counted the leaps when they ran it in the week before.

SoTexRattler

Heck, as long as you can SEE the destination house, an optical rangefinder, either pulsed laser type(time-of-flight) or the classic parallax type (spatially separated optical telescopes with variable angle 90deg mirrors.) can resolve very fine ranges.

K.

SoTexRattler

Also, once you get close to the edge of the house, someone in the house could drive a steel pipe or bar deep into the ground and someone could be tasked with tapping on it with a hammer to allow them to home in on the exact spot.. Once the bar starts answering back to you, you know someone has tunneled directly underneath that spot... More likely, they will have already started digging down to meet the tunnel rats.

K.