# Weird number signs on the highway in North Carolina **URL:** \ **Category:** Factual Questions\ **Created:** [January 25, 2015, 3:57am UTC](https://boards.straightdope.com/t/weird-number-signs-on-the-highway-in-north-carolina/710823 "2015-01-25T03:57:20Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![Red\_Stilettos](https://avatars.discourse-cdn.com/v4/letter/r/fbc32d/32.png) [@Red\_Stilettos](https://boards.straightdope.com/u/Red_Stilettos)\ **Post date:** [January 25, 2015, 3:57am UTC](https://boards.straightdope.com/t/weird-number-signs-on-the-highway-in-north-carolina/710823/1 "2015-01-25T03:57:20Z")
I returned home from a trip to Asheville, NC today. Because it was a sunny day, I decided to take the scenic route through the mountains. While traveling on the Great Smoky Mountain Expressway, I noticed a series of number signs on the highway that I’ve never seen before. Every now and then, I would see a series of square, brown signs each with a single digit. They would start with 1, then 2, then 3, up to 0, then they would count back down to 1 then 0 (a total of 20 signs in a row). The signs were about 30-40 feet apart. I saw this series of 20 signs several times, but they didn’t seem to be consistently related to anything (an exit, a bridge, etc.). Anyone know what these signs are for? ---
**Author:** ![burpo\_the\_wonder\_mutt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/burpo_the_wonder_mutt/32/365_2.png) [@burpo\_the\_wonder\_mutt](https://boards.straightdope.com/u/burpo_the_wonder_mutt)\ **Post date:** [January 25, 2015, 5:02am UTC](https://boards.straightdope.com/t/weird-number-signs-on-the-highway-in-north-carolina/710823/2 "2015-01-25T05:02:42Z")
This can’t be it, but: Gear-shifting signs for trucks? Or maybe gear-shift signs for bicycles if they have races through there? Total WAG. ---
**Author:** ![GreasyJack](https://avatars.discourse-cdn.com/v4/letter/g/df705f/32.png) [@GreasyJack](https://boards.straightdope.com/u/GreasyJack)\ **Post date:** [January 25, 2015, 5:20am UTC](https://boards.straightdope.com/t/weird-number-signs-on-the-highway-in-north-carolina/710823/3 "2015-01-25T05:20:18Z")
Some casual googling (including [this thread](http://boards.straightdope.com/sdmb/showthread.php?t=527580) from a few years ago) shows people saying they’re set up in fog prone areas for the purposes of gauging visibility on a camera. I guess that makes some sense, but that doesn’t really explain the weird up-then-down numbering scheme or if the numbers themselves have any significance. ---
**Author:** ![vomit\_comet](https://avatars.discourse-cdn.com/v4/letter/v/73ab20/32.png) [@vomit\_comet](https://boards.straightdope.com/u/vomit_comet)\ **Post date:** [January 25, 2015, 9:04am UTC](https://boards.straightdope.com/t/weird-number-signs-on-the-highway-in-north-carolina/710823/4 "2015-01-25T09:04:03Z")
Was it near logging roads? ---
**Author:** ![Iggy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/iggy/32/3364_2.png) [@Iggy](https://boards.straightdope.com/u/Iggy)\ **Post date:** [January 25, 2015, 10:15am UTC](https://boards.straightdope.com/t/weird-number-signs-on-the-highway-in-north-carolina/710823/5 "2015-01-25T10:15:58Z")
The signs can be seen on [Google Maps Street View](https://www.google.com/maps/@35.551793,-82.873682,3a,75y,257.1h,82.39t/data=!3m4!1e1!3m2!1s3XyO6QtHt-08x9CkEWkvSQ!2e0). Definitely for fog assessment. ---
**Author:** ![cornflakes](https://avatars.discourse-cdn.com/v4/letter/c/9d8465/32.png) [@cornflakes](https://boards.straightdope.com/u/cornflakes)\ **Post date:** [January 25, 2015, 4:30pm UTC](https://boards.straightdope.com/t/weird-number-signs-on-the-highway-in-north-carolina/710823/6 "2015-01-25T16:30:03Z")
The ones that I’ve seen were at overpasses or bridges, with the numbers counting down to the center of the bridge and then back up, more or less to the end of the Armco barrier. ---
**Author:** ![Simplicio](https://avatars.discourse-cdn.com/v4/letter/s/c37758/32.png) [@Simplicio](https://boards.straightdope.com/u/Simplicio)\ **Post date:** [January 25, 2015, 4:44pm UTC](https://boards.straightdope.com/t/weird-number-signs-on-the-highway-in-north-carolina/710823/7 "2015-01-25T16:44:25Z")
> [@Iggy](#): > > The signs can be seen on [Google Maps Street View](https://www.google.com/maps/@35.551793,-82.873682,3a,75y,257.1h,82.39t/data=!3m4!1e1!3m2!1s3XyO6QtHt-08x9CkEWkvSQ!2e0). Definitely for fog assessment. I think you can actually see the camera on a metal pole on the other side of the bridge there. ---
**Author:** ![Red\_Stilettos](https://avatars.discourse-cdn.com/v4/letter/r/fbc32d/32.png) [@Red\_Stilettos](https://boards.straightdope.com/u/Red_Stilettos)\ **Post date:** [January 25, 2015, 5:18pm UTC](https://boards.straightdope.com/t/weird-number-signs-on-the-highway-in-north-carolina/710823/8 "2015-01-25T17:18:52Z")
Thanks everyone. Fog assessment makes perfect sense, especially in this area. After all, they’re called the Smokies for a reason! ---
**Author:** ![Bijou\_Drains](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bijou_drains/32/2814_2.png) [@Bijou\_Drains](https://boards.straightdope.com/u/Bijou_Drains)\ **Post date:** [January 25, 2015, 11:15pm UTC](https://boards.straightdope.com/t/weird-number-signs-on-the-highway-in-north-carolina/710823/9 "2015-01-25T23:15:24Z")
as the other thread says, that smoke is not natural in all cases. It comes from a paper factory.