It only helps if the agency responsible for the warning signs updates them properly. Back in my hometown in Idaho years ago, they re-paved/re-surfaced the road down through an underpass. They added 2-3" of new asphalt. They didn't update the signs.
Thanks for cluing me into those reasons and tech. I didn’t realize a permit had to be issued for some rigs and loads. I have seen escorts for oversize vehicles, but they are not much further ahead or behind.
Could a pick-up with something like a whip antennae that’s the height of the load (or a couple of inches more) travel like a mile or so ahead and if it touches the overpass, a warning goes off in the vehicle and maybe even the carrier and escorts?