Mizter T wrote:

One should also note that this was a study from the early 70's when
ridership was on a downward trend. AIUI patronage of the Underground
has been going upwards since the 1980's. Plus of course new
computerised ticketing systems cost less to run than previous
arrangements.

To operate, perhaps, but not to procure, I'd think.

The principle seems to be being applied to bendy buses - the speed of
boarding at all three doors is presumably being offset against the
money lost by people not paying fares, but gained by the occasional
penalty fare. Buses, of course, have much more to gain time-wise by
not checking tickets than trains do.

Neil