Bob Noorda & Vignelli's signage for New York Transit (1960s)

Though they have been modified over the years, the signs New York subway riders see today are essentially the work of Mr. Noorda and Mr. Vignelli, from the bold, clean type to the color coding used to identify the system’s many train lines.

What do we see?  

1- identifiable codes,
2- few words,
3- friendly, consistent colors,
4- functionality,
5- familiarity