If memory serves me correctly when you see what looks like a stunted telegraph pole with a dayglo orange roof on the top that marks where the pipeline travels.

Correct a white painted pole about 5 feet high with dayglow orange “roof”.
Usually within a few feet of it there is a “headstone” with a plaque indicating either it’s purpose …coded like the letters on the back of tanker trucks, or like the one near where I live the company name and a warning not to excavate 50 metres either side of the the marker, due to a high pressure pipeline.
I live near the Ineos owned main pipeline that runs south from Grangemouth.