I can’t seem to find a link, but I know there is a fog-prone Interstate zone in eastern Tennessee (probably I-81, might be I-40) with variable speed limit signs

I can’t seem to find a link, but I know there is a fog-prone Interstate zone in eastern Tennessee (probably I-81, might be I-40) with variable speed limit signs not terribly different from those on UK smart motorways. Hungary has an elegant, low-tech solution. Broad white stripes are painted ~100 m apart on the shoulder of the road. Fixed signs indicate the allowed speed - if you can see three, it’s 130, two is 110, one is 80 (or something like that - it’s been a few years).