I was very excited to see that this week's New York Times Magazine has a big article about the development of Don Meeker's and James Montalbano's ClearviewHWY typeface, available here. (For now, I don't think you have to be a NYTimes subscriber to read it, but that may change in the next few days.) It describes the problems with FHWA Highway and how Clearview offers improved legibility from a large distance. It also has a brief section of typographic terminology and sans-serifs. I thought it was pretty interesting and typographically-sensitive, although a good deal of the stuff on Clearview can be gleaned from its website. There's also a highway sign slideshow with some images not in the article.