"David Cantrell" wrote in message
k...
On Sat, Dec 12, 2009 at 02:33:33PM -0800, Chris wrote:
On 12 Dec, 15:09, MIG wrote:
I suspect that validators in trains now would be hugely expensive,
Too right - they would have to be permantently in touch with the
central database!

Would they? I don't think the ones on buses are.

They aren't, but bus validation is simpler than other transport modes. I
wouldn't expect an on-train validator would need permanent contact with the
database because the current system must allow for the possibility that
station-based validators might not be able to access the central database
all the time. I would expect an on-train validator might need a bit more
intelligence built into the validator itself, which would be a maintenance
overhead, and they would also need an accurate idea of where the train was
so that they could flag the correct entry or exit on the card.

D A Stocks