Michael R N Dolbear wrote:

Mizter T wrote i
.
Just noticed that TfL has launched a new facility on the fares
section
of their website - a "Single fare finder".

http://www.tfl.gov.uk/tfl/fares-tickets/fare-finder/

You input your start and finish station - the fares finder is replete
with a javascript auto-complete function - then select adult or child
and and click on "Show fares".

The applicable fares are then listed - the far cheaper Oyster fares
comes first (both the peak and off peak fares are listed if there's a
difference), followed by the pricey cash/printed ticket fare.

It's basically just a friendly front end to a simple database that
lists which stations are in what zones.

Err, that wouldn't work. The fare finder has to know how many zones
have to be crossed for a reasonable route from A to B and whether this
includes zone 1

I recall it being noted on this NG that some Oyster fares assume a zone
one route is taken. A simple lookup for fares would have 20,000+
entries, making all the contiguous stations on one line in one zone one
entry would chop this down a good deal.


When I say it's a "friendly front end to a simple database" the
simplicity thereof is of course all relative - such a database could be
regarded as simple when compared to, say, the Sainsbury's Nectar card
database.

In fact I'll stop trying to justify my ill-thought out comments with
that somewhat weak excuse!

But I can give a better justification - perhaps all the fares between
any two listed stations have already been worked out and are merely
stored in a massive table with the 'most likely route' between any two
stations having already been decided by a human, so when you query the
single fare finder you're merely doing a lookup of this information
rather than having the information generated live (as it were).