One thing I've noticed looking at old button copy signs is that their typography looks notably different than it does on retroreflective signs. I've heard at least some talk of an FHWA series D Modified and a C Modified, but I still have no information on the way Series E Modified looked with button reflectors.
For one, the descenders on the lowercase "g" and "y" are longer when compared to the new version of E(M). It looks to me like the lowercase letters are also a fair bit narrower than they are in the modern typeface. Has anyone else noticed this at all, and is there anywhere I could potentially find more specifications on those typefaces?
You won't be able to find more specifications on them because...there aren't any. The Series E-Modified we have now is the one they had in 1948.
However, button copy manufacturers had problems using the fonts as specified because sometimes making a whole number of reflectors of X inches in diameter fit in a stroke that is specified as Y inches long just didn't work. So the glyphs had to be adjusted by doing things like lengthening descenders and tweaking curves. These modifications were done in-house by the button copy manufacturers themselves, and as such the specifications for these modified glyphs were never published and probably don't even exist anymore.
As for D(M), that's a real thing, but it was never specified by FHWA. It was invented by Caltrans, and I don't think it was ever formally called that. On the guide sign shield specs dated December 28, 1959, it was merely specified as "D*", with the asterisk leading to a footnote specifying that the stroke width should be 0.18" per 1" of letter height.
In Inkscape, D(M) can be created by using an Offset path effect (Ctrl+Shift+&) with the width set to the difference between native stroke width and 0.18 times the X-height in inches, divided by two. (It is recommended that you then Ctrl+Shift+C to permanently apply the Offset path effect. Live path effects can exhibit squirrelly behavior when the underlying paths are modified, scaled, etc.)
Quote from: Scott5114 on March 14, 2022, 02:29:46 AMAs for D(M), that's a real thing, but it was never specified by FHWA. It was invented by Caltrans, and I don't think it was ever formally called that. On the guide sign shield specs dated December 28, 1959, it was merely specified as "D*", with the asterisk leading to a footnote specifying that the stroke width should be 0.18" per 1" of letter height.
Series D Modified started as Series D in the Caltrans alphabets, which were essentially bolded versions of the FHWA series. (I've never seen a full set of letter drawings and the engineers I have talked with at Caltrans have expressed doubt that one still exists. I do, however, have a 1980's house publication on guide signing with a table comparing stroke widths between the Caltrans and FHWA series.) Arizona DOT used the label "D Modified" for bolded D in a version of its
Manual of Approved Signs that was originally published in print only, and I have been told that Minnesota DOT used "D Modified" as well in its sign drawings book. This was long before such resources were routinely published online.