Out in the western 'burbs, we see these roadside, mounted signboards all over the place. Of varying sizes, they’re all basically the same design: a pole between three and five feet high, straddled by back-to-back numbered placards in the shape of a tent. I’d been wondering about their purpose and finally got an opportunity to scope one out up close enough to take this photo. The verbiage on a second pole in the foreground, which sports a BP logo, cautions that it marks a petroleum pipeline. I assume the number is a location identifier? Do other utilities keep tabs on their underground lines using similar systems?
Underground gasoline, oil, natural gas, etc. pipelines are all marked in a similar fashion. If you’re curious, your local Emergency Management Agency will have maps showing all the pipelines in their area.
The number is typically a mileage marker, and the signs are designed to be spotted from aircraft.
And usually the colors designate who’s line it is.
I knew a man who inspected a gas pipeline between Oklahoma and Chicago ever week. It took him 2 1/2 days each week. Eight out of 10 inspections were uneventful. If he saw construction (or any problem) near the pipeline, he would call it in, “Have someone check out the pipeline between marker 423.5 and 424”
In the 70s when I worked on a survey party, we ran into a path in the woods at a small subdivision we were working on in Port St. Lucie, FL. It was AT&T Long Lines and their underground lines were marked by a well-mown path about 100’ west of US1 going down to Miami or further, I assumed. The path was about 10’ wide and had signs posted at regular intervals identifying it, even down to how deep and far from each post the cable was buried, and a number to call before you dug nearby. The path was certainly visible by air but I don’t remember any of the type signs the OP mentions.
Around here, Missouri, the phone lines are marked with a plastic post about 5’ tall and 6" in diameter. Has a reflective ID band around the top. If the line gets cut its a problem to fix, but at least there’s no fires or oil spills to clean up.
Lots of different ways to inspect all sorts of transmission lines.
Petroleum used to a walker, then small planes, some Helios, now some scanning devices from higher up, it is constantly changing.
Electrical transmission lines are usually by Helios because they need to be closer to see more detail so they need to be slower. Then they have the guys in Faraday suits who actually crawl along the lines next to his Helios service craft. Some still use walkers going along underneath.
Going S/W out of the Tulsa refinery area is a huge right of way with maybe 10 pipelines in it from a lot of different companies.
As a patrol pilot, we could not tell for sure which line might be leaking so as the different patrol companies pilots would report leaks or problems all the companies just took turns going out to fix things. Did not make any difference who’s line it was. It all evened out as to cost for each in the long run.
Unless right near a mile marker or on a really big cross country line like the OMR or the Explorer, problems were reported as ( so many feet/yards South from the barn in the S/W ¼ of the N/E ¼ of section # 21 in T 6N & 12 E. ) We used county maps made into strips maps which were rolled scroll style so they could be used one handed.
I would think by now that GPS would be in wide use.
Biggest I ever found was 5-6 thousand barrels and the smallest was a ‘tea cup’.
A small leak had just started from a 6" crude pipe that was jumping over a gully with clean sand in the bottom & I caught a flash reflection from the falling drops so I circled back and could see the 3" spot on the sand where it was dripping to.
It was a hoot to report, the dispatcher took three repeats before he understood the amount and I still had to explain how I saw it. Bawahahaha
The big leaks gushing 30 feet in the air are not so hard to find.
I was also the pilot on some of the first Bendix scanners using liquid nitrogen doing civilian commercial work.
I was the pilot for the first civilian use of Tomography for pipe line patrol with the older Germanium lenses. Both were early Temperature scanners down in the IR ranges.
Gah, I’m so old…