The limits are by value and volume. You’ll have to enter your PIN for transactions above £30 - but this is nothing new. You will now also have to enter your pin after your fifth consecutive contactless transaction, or once you reach a cumulative amount of consecutive contactless transactions totalling over £135.
There will be some exemptions to this - most unattended payment terminals won’t ask you for your PIN after five transactions and you’ll be able to pay through contactless as many times in a row as you like. This means you can carry on using TFL as normal!