Something here is not quite right. For example, if you look at the 7th ave line (red line/1,2,3) 18th street and 14th street have similar radii.

But anyone knows that 14th street is much more convenient because it's triply serviced by the 1,2,3 with 2,3 being express trains. 18th street is serviced by one train the runs locally. This ignores that you could easily switch to the L, A/C/E, F/M with a short walk.

Still, a cool visualization to show the power of mass transit, and even compare relatively between lines.