From the BBC Website
Contactless bank cards are to be introduced on London's Tube, DLR and Overground trains.
From 16 September, people can use the cards instead of having to top up their Oyster Cards, although these will still be in operation.
Transport users are being advised to avoid paying twice by making sure only one card touches the reader.
Contactless payments work in the same way as the Oyster cards by touching in and out on the readers.
'Easier for customers'
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image of Tom Edwards
Transport correspondent, London
Oyster has been a huge success story but it's getting on a bit in technology terms.
Tfl wants to move its services over to contactless payments to save it money in backroom operations and collecting cash and it will also give it added flexibility, including "auto-capping" your travel.
A trial has been a success but there are some anomalies.
The trial included rail services but as yet, the train operating companies haven't said they'll accept contactless payments on 16 September and without the rail network involved, it will get tricky for commuters.
Commuters also have to watch out for "card clash" - if an Oyster card is next to a contactless card in your wallet, the fare could come off the unintended card.
You can see paper tickets and travelcards becoming a rarity and everyone one day paying with an Oyster or bankcard.
Only one payment will be sent to the bank or financial provider for payment.
In addition to daily capping - when travellers taking multiple journeys will not pay more than the cost of a Day Travelcard - a new Monday-to-Sunday cap will be introduced for those using contactless cards.
This will mean that the best value over the course of the week will be automatically calculated.
All UK-issued contactless American Express, MasterCard or Visa credit, debit, pre-paid or charge payment cards will be accepted for payment.
Other methods of contactless payment that meet financial industry standards, including mobile phones, may also be accepted, with users of the EE network able to pay via the Cash on Tap app.
Some non-UK cards may not be accepted and card holders should check with their issuers