Dr J R Stockton wrote on 13 February 2010
21:23:23 ...
In uk.transport.london message
dia.com, Fri, 12 Feb 2010 15:30:59, Richard J.
posted:

The technology might be OK if the resolution is high enough, but in
practice you get crude letter shapes with the letters g,j,p,q,y not
descending properly. If "backward" means retaining the elegant and
highly legible Johnston typeface, I'm all for it.

I have had 7-pin printers which used the middle 5 pins for "e", the
upper 6 for "E", the lower 6 for "g", and all bar the second for "j".
Characters were 7 dots wide, with the restriction that no pin could fire
in adjacent columns. The result was surprisingly legible, given those
limitations. Descenders should descend "below the line", but do not
need to descend far if, for "gpqy" the bode of the character does not
use the sixth row. Someone tell TfL.

Designing a typeface that is legible on a moving vehicle at a distance
is rather more demanding than cobbling together a few dots on a piece of
paper. TfL are more careful about legibility than most other transport
operators, and I applaud their approach. The one area where they have
fallen down is destination displays on new tube trains, which are not
nearly as clear as the old blinds. I wouldn't want them to go down the
same path with buses until higher-resolution displays are available.
--
Richard J.
(to email me, swap 'uk' and 'yon' in address)