Sunday, June 18, 2023
Famously most of the Underground is actually overground.
But what of the individual lines?
Well, someone's put in an FOI request.
Inspired by the Tube map showing tunnels, I would like to know how much of each line on the London Underground is covered by tunnels.
And TfL have responded.
Using GIS data that we hold, we have calculated what track sections are below ground and the totals for each of our Tube lines as below.
And hey presto we have an answer.
These are the undergroundiest Underground lines.
•• The Waterloo & City and Victoria lines are the only lines to spend all their time underground.
•• The Northern, Circle and Hammersmith & City lines spend roughly two-thirds of their time underground.
••• The Jubilee, Bakerloo and Piccadilly lines are roughly 50/50 (the Bakerloo almost perfectly so).
•• The Central and District lines are roughly one-third under, two-thirds over.
• The Metropolitan line is barely underground at all, relative to all the time it spends out in the suburbs.
I made that graphic and tweeted it and it's proved particularly popular ❤️371
It also accumulated replies from people who hadn't read the FoI request I linked to.
→ Victoria 99%...surely.
→ Didn't know that Northumberland Park Depot on the Victoria line was underground 🤔
Never risk a surely if you haven't checked the official caveats.
They specifically said "excluded - sidings, depots, spurs".
They also didn't calculate a value for the Circle line, they just said "circle line falls under district and hammersmith".
That meant I had to estimate the Circle line for myself, so the Circle line percentage is not official.
There's no indication that Secret London noticed this when they regurgitated my tweet two days later.
Also certain people assumed I'd missed some key data out.
→ Don't forget the DLR, Elizabeth line, London Overground and Tramlink!
→ What about the Elizabeth Line?
These are not Underground lines, even if you mistakenly think they are.
But we can do some estimates if you like.
• The DLR has a few significant tunnels among 42km of track, so maybe 15% is underground.
• Crossrail is about 18% underground, that's easier to calculate.
• The Overground is about 3% underground, so much better named than the Underground.
But best only trust the official data, and always read the smallprint.
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