The introduction of Oyster Route Validators will mean that the Oyster "By touching the pink reader en route - in addition to touching in and out.
The pink oyster readers are " route validators ". It's more expensive to travel through zone 1, so if you take a route that doesn't take you through.
"From September 6, all Oyster pay-as-you-go passengers should touch on a new pink Oyster route validator reader when changing between..
Route validators pink readers - - flying
This gives users of that line an unfair advantage when making journeys that are more likely to be undertaken via London Bridge. Unfortunately the publicity is not quite nuanced enough. A couple of other things about pink validators. There is no pink reader at London Bridge as you have to touch out and back in again when changing between NR and LU.