JB wrote in news:nocop3tpoan12q2qlafl4vrlsrspljpfqt@
4ax.com:

However they initially claimed that I would need a R3456 and a zone
1-3 travelcard, as a R456 and zone 1-3 would not cover the journey
over the boundary between zone 4 and zone 3.

I pointed out that a R456 would cover the journey up to the boundary
of zone 4 and 3, and that the zone 1-3 would cover the journey onwards
from the boundary of 4 and 3, and thus there was no 'gap'. I also
pointed out that extension tickets or excess fares on a zonal ticket
are calculated from the edge of the boundary, not the last station
within the zone.


I suspect this is one of the reasons why the rules do not require the train
to stop when changing from one zonal season ticket to another zonal season
ticket.

Clearly a Zone 1-3 and a Zone 4-6 ought to cover the entirety of Zones 1-6
- but finding a train that stops at the point you change from one ticket to
the other (in the case of FCC midway between Alexandra Palace and New
Southgate) could be rather difficult...

David