The old signs were larger and more readable from a distance. This could be made more readable by dropping the light text on dark background. Repeat after me: black is the first colour, white is the second colour, red is the third colour. 500 years of trial and error has validated this. Twenty-five years of public display of computer screens has re-invented the wheel as a square.

Quantity or size? These signs (LCD monitors actually) are everywhere in the station. There really isn’t the same need to read them from a distance there was with the old signs. There is at least one at every access point to train platforms and dozens in the concourse area. The old signs couldn’t handle enough schedule info for the amount of traffic these days.

The white-on-black is the new standard for high-constrast signage. For people with partial visual imparments, it’s much easier to read than black-on-white. The 500 years of trial and error you speak of is predicated on oil-based ink and the fact it’s cheaper to colour part of the page than all of the page. With technology, the cost is reversed.