Definitely worth a look to see how a major transit agency puts together a comprehensive guide to assembling consistently designed maps. The guide deals with horizontal in-car strip maps and the vertical line maps seen on platforms, but many of the principles still hold true for the design of a full transit map.

Of particular interest is the relationship between the x-height of Johnston Sans and the thickness of the route lines (they’re the same). This value of “x” is also used to calculate the radius of a curve in a route line: the innermost edge of a curve is always three times the value of “x” – never any less. Almost every relationship between objects on the map is defined mathematically, although the nomenclature can be a little less than intuitive sometimes: “x”, “n” and “CH” all make an appearance!

Also, if you ever wanted to know what the PANTONE or CMYK breakdowns for all the Underground route line colours are, this guide tells you that, too!

All in all, a really interesting read – just try and ignore the terrible typos that pop up here and there: “donated” instead of “denoted” on page 11 is my favourite! Click the link below to download the PDF.

Source: Transport for London website – 2MB PDF