In message , at 12:11:34 on
Sun, 3 Aug 2014, Paul Corfield remarked:

The problem with extending Oyster is that it has a very finite number of
price-zones and it's possible these were exhausted when extended to
Shenfield.

I asked TfL's ticketing people, via a Twitter "chat" session, if they
would technically cope with the indicated TSGN franchise plans to
extent Oyster beyond the zones. They said they could. Unfortunately I
can't send you a technical specification to prove this

Do you have them, or a relevant summary?

so I imagine my statement will go on your vapourware list of probably
untrue nonsense ;-)

Vapourware isn't stuff we believe is a lie, or that will never happen;
it's things which have been over-optimistically and yet firmly
announced, but keep slipping (it's possible, after some practice, to
spot the inevitability of this for specific announcements).

Although many do eventually slip so far they get overtaken by events and
hence never see the light of day.

This suggests there is some system capacity left but I imagine there
may also be assumptions about pricing and keeping stations priced on a
consistent basis outside the zones.

How many extra places are TSGN expecting to cover? [1]

When Oyster zones were last discussed here (about 18 months ago) it was
in terms of 12 zones already used and a maximum of 15.

If Oyster PAYG is to extend to Dartford that will solve a great many
problems although it might reduce South Eastern's penalty fare income.
It's hardly likely to be a huge problem given Oyster based Freedom
Passes *are* valid to Dartford so there must be some ticketing logic
in the system that allows those cards to be read (I assuming the gates
at Dartford *do* read them - happy to be corrected if actual practice
is different).

It's not about being able to read the cards, but having enough 'zones'
to cope with all the different charging possibilities. Although that
assumes that all 'outlier' stations need a zone of their own.

Are current Oyster fares from central London to Harold Wood and
Brentwood identical (a "mid-Essex" zone) and if so what would Oyster
charge for a journey from Harold Wood to Brentwood?

Any expansion plans are (conceptually if not for implementation) as
simple as there being many more sets of stations like Harold Wood and
Brentwood identifiable so they can work out the right fare to charge
from Shenfield variously to Harold Wood, and new places like Luton
Airport and Dartford and perhaps other similar ones just outside the
current limit like Swanley, Esher and Hinchley Wood.

[1] Later... Apparently Greater Anglia are committed to several, viz:
Theobalds Grove, Waltham Cross, Cheshunt (inside the exiting zones)
Brentwood, Shenfield (already delivered, outside the zones) plus
Broxbourne, Rye House, St Margarets, Ware and Hertford East (outside
the zones).

Govia Thameslink Railway (aka TSGN) are saying they'll extend Oyster
"as far as Epsom, Gatwick Airport, Luton Airport, Welwyn Garden City
and Hertford North" which if we count intermediary stations is quite
a few.
--
Roland Perry