> What happens if there's no credit and you thought there was
Initial authorization only takes £0.10 and is there to validate your card is active.
The actual charge gets applied 24h later and can overdraw even an account with no arranged overdraft through a transport-only exception with the card networks.
In the end it means you only need 0.10£ to travel for 24 hours, and can keep doing so as long as you fund your account before the initial 24h period (if you fail and it declines it'll retry up to a few days, and there's a way to make it retry online - until it succeeds, that particular card will get refused at the barriers).
Initial authorization only takes £0.10 and is there to validate your card is active.
The actual charge gets applied 24h later and can overdraw even an account with no arranged overdraft through a transport-only exception with the card networks.
In the end it means you only need 0.10£ to travel for 24 hours, and can keep doing so as long as you fund your account before the initial 24h period (if you fail and it declines it'll retry up to a few days, and there's a way to make it retry online - until it succeeds, that particular card will get refused at the barriers).