London Banter - View Single Post - Oyster and oneday Travelcards -- when?

Paul Corfield · June 19th 04, 09:30 AM posted to uk.transport.london

On 15 Jun 2004 16:10:43 -0700, (Gareth Davis)
wrote:

"Ben Nunn" wrote in message ...

Capping needs to be introduced, and it needs to be smart and effective. The
£90/50 Prepay limit needs to be abolished and the 'nominate a specific
station to pick up your credit' thing must go. Also, a Non-prepay
Pay-as-you-go that bills your credit/debit card would also be far better
than having to add value to the card periodically.

Performing all the calculations required to get the 'instant' capping
to work (based on your last few journies) in the time you have your
card over the reader then to write back the refund to the card while
it is still in range is a non-trivial exercise - and is limited by the
length of the journey record kept on the card. This record needs to
hold every journey over the capping period for the calculation to be
correct.

For example if only the last 10 journeys are held and the period is 24
hours then a two zone tube journey could be made on peak (£2 prepay),
followed by 10 bus journeys (that would be capped at £2.50 for a one
day bus pass), followed by another £2 tube journey. The bus journeys
would have 'pushed off' the first tube journey resulting in a £6.50
total for the day rather than a £5.30 day travelcard because the first
journey can no longer be 'seen' by the program in the gate responsible
for the capping. While I admit this is a very contrived example it
illustrates the problem well - especially if the capping period is
scaled up substantially (to say, 1 week) without increasing the
journey storage capacity on the cards. And once you increase the
amount stored on the card it takes longer to read and write back -
causing lots of '96 Seek Assistance' errors as people pull the cards
away too fast without waiting for the green light. These are not easy
(or cheep) problems to solve - which probably explains the length of
time it is taking to come up with a 100% working solution - if one is
ever found.

Right - I have NOT seen the official documentation for capping but
surely the logic is something like this from your example.

Z12 peak Tube journey - automatically means that the ticket capping
price has to have Tube validity, cover Z12 and be peak priced. As NR
stations do NOT have validators you will be capped to the Z123456 One
Day LT Card price £8.20. All subsequent pre-pay journeys will simply
add up against this total until it is exceeded. If you travel to another
zone beyond Zone 6 then the cap will increase.

Where this gets horrendous is the complication with NR services. One Day
Travelcards are obviously valid on these services but if Pre-Pay
validation facilities are not available at the majority of stations -
and they aren't - then I do not see how TfL can introduce capping set at
Peak or even Off Peak One Day Travelcard prices because the validity of
the pre-pay capped product cannot match that of the paper encoded
ticket.

Another poster mentioned the Tramlink issues and while I understand that
issue as well as the DLR "within gateline" validation issues I think
these are small scale when compared with the fundamental pricing point.
I suppose TfL could introduce a surrogate LT Card pricing scale that
sets caps for Z12, Z1234 combinations as well as off peak prices to
avoid everyone howling that a cap of £8.20 is a rip off.

Other issues to be borne in mind include how capping works with rail
replacement services, when gates are in evacuation mode, when tube
passengers are transferred to local bus services and when a station
close to or at a zone boundary is closed and people have to travel
beyond their zone to exit. If such a journey was to trigger a higher cap
being activated then the public would be rightly annoyed. While the LU
system has features to cope with these eventualities and they were in
the very earliest documents I saw these need a significant amount of
testing in order to ensure they work seamlessly and that the public can
be told that they have not been financially disadvantaged.

--
Paul C

Admits to working for London Underground!