Reading about Clearview and traffic signs reminds me of the efforts of designers Margaret Calvert and Jock Kinneir. They standardised fonts and sign designs for the UK in the late 50s just as the rollout of motorways was being planned.

They came up with two fonts expressly for ease of readability that stand the test of time remarkably well.

https://en.wikipedia.org/wiki/Transport_%28typeface%29 and Motorway (font).

They also standardised many of the pictograms for use on warnings, colour schemes and iconography. They also did the rail and airport alphabets.

http://designmuseum.org/designers/jock-kinneir-and-margaret-...