About a month ago, I went to Hays for the weekend and spent some time driving around the area. Most of the signs that I saw had been replaced at some point between 2009 and now, so they used mixed-case Series D. I noted that they looked pretty sharp since they didn't use the official FHWA implementation of Series D. I didn't think much of it at the time, though, since I assumed they were using the typical non-federal "chocolate" glyph set that has floated around for a few decades, often under the PIXYmbols or Page Studio Graphics names.

(from GSV)
Today I had reason to look at it a bit closer, and cracked open the latest KDOT plans set, 106 KA 6106-01. What I found was pretty shocking. Much like the LeHay fonts of yore, but way, way more subtle, I discovered that KDOT has a unique Series D implementation of its very own.


You can see on the first image that there are some very subtle, but noticeable, differences between Kansas's Series D and both of the other Series D implementations when they're overlaid. I'm actually pretty impressed that someone took the time to draw these glyphs up; they fix pretty much all of the awkwardness of vanilla Series D, open up some of the counter spaces to reduce the impact of halation, and are just all around a very tasteful implementation of the typeface.
One caveat is that KDOT plans of course come from PDFs generated from SignCAD, and these have some very noticeable "plotteritis", being made up of all corner nodes and not actually smooth edges. Also, there are Series C and B glyphs in this plan set that are very weird and clearly not intended to be used as-is. However, the D glyphs seem to match the signs I saw in western Kansas more or less exactly, and could be reworked to create vector-quality illustrations without much effort. Of course, I'm missing f, j, x, and z, so I'll need to procure those before I could make a font or anything like that. (Too bad there's no conventional-road signage for Fairfax...)
Anyway, there you have it. A modern-day custom font, actively in use in 2021.