I recently spotted Geoff Marshall's unboxing of this live animated LED Tube
map, which shows all LU train movements in real time. Trains on 12 lines
are represented with 333 appropriately coloured station LEDs, but how do
you represent Northern Line trains? Yup, in white.

Just the thing for a Tube nerd with £249 to spare! An ideal present for
someone who grew up in London but now lives in exile.

https://www.traintrackr.co.uk/product/tfl2