UK, especially London, dopers: Is “alight” common usage?

Or at any station with a curve in the track/platform.

Of course, but that doesn’t make it ‘common parlance’ which means that many people use it in ordinary speech. Most people would say ‘get off’.

I think it’s worth pointing out that the Tube is an historic metro network of proud tradition - its iconic map and logo, ‘mind the gap’, its history as an air raid shelter during the Blitz, even its typography. It has a tightly controlled brand and no doubt the tone of voice guidelines have rules to ensure traditions are followed in the choice of language. There’s a lot of nostalgia in those tunnels.

Quite so.
For example Arnos Grove station (on the Piccadilly line) was designed by architect Charles Holden, and has been described as a significant work of modern architecture. On 19 February 1971, the station was Grade II listed.

Fun fact: Jerry Springer was born on February 13, 1944 in Highgate station on the London Underground.

I’ve heard ‘alight’ on the Tube as in “Passengers wishing to change to the Victoria Line should alight at the next stop.”
Sadly I’ve heard it on the news as in “A protester set himself alight…”

I’ve also often wondered about the etymology of “alight”. It’s obviously related to “light”, but does that mean light in the sense of brightness (when I alight from a bus, I’m stepping out of the darkness of the bus into bright sunshine) or light as the opposite of heavy (when I alight from a bus, the weight that’s on the bus is reduced by my weight)? I checked an etymological dictionary, and it seems to be the latter.

Yes, I think the latter. It calls to mind the image of a bird temporarily touching down and taking off again, but maybe that’s just me.

When they first started building underground railways in London back in the 19th century, they built them under the old medieval streets to avoid wayleave payments to property owners and reduce possible claims for damage during construction and operation. The platforms under Threadneedle Street and Poultry are so curved that one end of the platform cannot be seen from the other.

Trains announcements have a language all of their own. “This train terminates here” isn’t something most people would say.