The New York Times has a very interesting article on the development of “Clearview”, the new font being rolled out on the country’s highways (or motorways, if you prefer). The font is designed to combat the effects of phenomenon halation, where the reflective material that’s used to make the signs more legible at night blows out the letters & dazzles drivers. This is particularly an issue for the elderly, an increasingly large segment of the US population, but it also can effect those with common sight defects. The designers, James Meeker & John Montalbano, opened up the counter shapes (the interior shapes of letters) & increased the x-height (size) of lower-case letters while retaining the stroke weight of the letters as they currently are.
An interesting fact from the slideshow (well worth exploring if you’re a font nerd) is that the typeface achieved “approximately 40 percent gain, or 200 feet of added reading distance using a 10-inch heigh letter on the demonstration panel”.