[tjohns]

As someone who grew up in the mountains, I can tell you that the plows (and tire chains) do a fantastic job of stripping all the road markings away.

[falcolas]

I see this in the valley too. Lane markings are more "lane suggestions" for about 8 months of the year. Abrasive sand for traction on the ice, metal plows scraping the pavement, tire chains, and good ol' erosion do a great job of removing the lines they finished putting down in August by December.