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I don't understand how they could implement the savings / spending caps for contactless cards but couldn't do it at the same time for Oyster cards. It's insanit

• lmz 5y ago
  The contactless cards are logged then charged centrally. Stored value cards are charged at the gate. Central charging allows more flexibility as you have more data to work with.
• blibble 5y ago
  oyster does have spending caps, but not the more complicated calcuations why? oyster is a stored value card the barrier where you tap-out calculates and takes the money off the card instantly, and given the interaction time to get you through the barrier the computation is necessarily limited whereas a contactless card is effectively being a pointer to a bank account that can be charged at a later date for TfL there is a batch process at the end of the day which does that
  • zimpenfish 5y ago
    > for TfL there is a batch process at the end of the day which does that Which can lead to some perplexing notifications from your bank at 0400 when it says you've just charged £N at A.N.Tube and it takes you a good three minutes before you realise it's not someone cloning your card but the journey you made 18 hours ago.