Found a bolted manhole cover in the middle of the woods

It's what is known as an Underground Cable Vault (UCV). I work with them every day.

Under the manhole cover is a square vault, usually about 10-12 feet on a side. Through it runs fiber optic cabling. Inside there is probably what is known as a "service loop" tied to iron racking on the walls of the vault. The service loop provides slack in the cable should it ever be cut or need to be spliced.

If you were to open the manhole there's probably better than a 70% chance all you would see would be water. Most of them are full of water (the cables are designed to be in submerged environments indefinitely).

AT&T is by no means dead. They are very much alive. They don't sell residential telephone service anymore, but they remain a mammoth international carrier for voice and data services around the globe. In fact, AT&T is so mammoth that most major telephone companies lease bandwidth on their cables. Many telcos would not be able to even function if it were not for AT&T's cabling infrastructure across the US and many parts of North America. AT&T is the World's largest telephone provider, by orders of magnitude (even to this day).

If you were to dig down along side of this manhole you would encounter a metalic plastic tape with some serious warnings on it, called "Scare Tape", at about 3 feet below the surface. Below this you would likely find a series of 4" conduits buried in red colored concrete. And if you were crazy enough to ever attempt to cut one of these cables there would be helicopters on top of you in a matter of minutes. The fiber optic cables run in bundles of 144 and 288 strands of "single mode" fiber optic cabling (inside of a single jacket). One of the fibers inside these cables (about the size of a human hair) is dedicated to an "Optical Time Domain Reflectometry" function which will zero in on the location of a cable cut (down literally to the inch) from 300 miles away.

And yes, cable damage to one of these cables really can cost upwards of $1 million dollars a minute! It's not a myth. And, repairing one is not easy. Some repairs can take days. I know (personally) of a large earthwork company who went bankrupt overnight after cutting a transcontinental SPRINT cable.

ETA - Current technology called "Distributed Acoustic Sensing" monitors cable disruption. If you were to just put a wrench on one of the bolts on that manhole cover people in AT&T's operations center would know. If you were to pound on the lid with a sledge hammer or large rock there would be a helo in the air in minutes to come check it out with an overflight. You might ask yourself how then can cables which run under busy roadways not set off alarms all the time? And the answer is, because the technology can be 'attenuated' to ignore normal noises and vibrations and only alarm on off-normal conditions.

Note: Your manhole find is actually surprisingly well marked. Most are not.

Fun Fact: Do you know where you can almost always find a SPRINT fiber optic trunk line? Answer: along side a main railroad line. The "SPR" of the word 'SPRINT' stands for "Southern Pacific Railroad".

a reply to: Flyingclaydisk

Thanks, this is the kind of answer I was looking for. I knew it had something to do with cables, I just didn't know what exactly was actually inside.

a reply to: Flyingclaydisk

 The "SPR" of the word 'SPRINT' stands for "Southern Pacific Railroad".

Thanks for that.
I learned something else new today .

originally posted by: FinallyAwake
I think that you should open it and investigate.
But don't be too surprised if 1 second = 1 year when you're down there! 😁👍🏻

Don't be surprised if you die from the lack of oxygen down there. Two guys just did the other day.

No conspiracy. A transcontinental interconnect cable is routed under ground. Ive done excavating like this years ago. This would be called a "Duct Package" A trench is dug, then 4-8 8"diameter pvc pipes are placed in the ground. The cable will be routed through the pvc pipe(s), then the trench is filled with concrete and slurry, then covered. (If you dug down anywhere along the path you would hit a block of concrete)
Although there may be only 1 cable, they may install up to 6 pipes and only use one of them. The unused pipes are there for emergency repairs, same as the manhole covers. With any underground duct package, access holes (like the manhole cover you speak of) must be placed at certain intervals so the cable and duct work can be accessed.
If you opened the cover you would see an empty space big enough for a person, and pipes coming though the wall into that space, one set in, one set out, and wires coming from those pipes. The wire would be looped (this is in case there is a break in the line) with plenty of excess, then the wires would enter the other wall 180° opposite of where they came in.
That is a Transcontinental cable way for ATT and it connects Asia, North America, and europe. So ots kinda a big deal. It is in a remote location to prevent any damage to it, also to avoid other underground cable routing.

a reply to: Brian4real

You know that, I know that, but, the ignorance is strong in some people. I hope that nobody tries to go down one of those manholes.

I worked with phone company line crews for a few years. I was trained to certify manholes as safe for workers to go into. I was also trained in confined space rescue. Many, many times manholes in areas that you would think were safe, set off the alarms on the gas meters.

www.foxnews.com...

a reply to: JIMC5499

Many, many times manholes in areas that you would think were safe, set off the alarms on the gas meters. 

VERY good point! I didn't consider that issue!