On the new NR gatelines at LBG, there are overhead gantries (to the average passenger, they appear much like tidal flow controls on roads) to indicate the availability of the barriers, with an option to display either a red cross or a green arrow. What I'm wondering is whether this could be adapted to also show if a barrier is Oyster/ticket only, as well as open or closed, at very busy LU stations (I am thinking of places like termini, or perhaps destinations such as Oxford Circus, etc.)...? It could prevent people having to shuffle backwards into a seething throng of passengers after they realise that their card or Oyster will be - or has been - rejected.
Just a thought!