It doesn't work when you have an 11 foot tall P800 and a 9 1/2 foot high railroad overpass. I know 2 drivers who have unsuccessfully attempted this technique. Also, management frowns upon this procedure.
I know exactlythe scenario you describe since one of my old routes was like that. I can verify that that would be a dumb attempt. and no I have tried that. Mine was a old P1000 and I could just get under the thing. It was one of those that hang from chains and swings.
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This is what my truck looked like when I got back to pavement. At this point it was 12:05, had 21 stops done, and 56 miles. I sorted until 12:35. I ended the day with 104 stops, 153 miles and c/o at 20:24.
This is where I live in Manhattan. Hidden beneath all those trees are streets and houses, one of them being mine. This area is in NE Kansas and is called the flint hills so it's not quite as flat as the rest of the state. This is what it looks like in the fall!