Well. This is one of the weirder tube maps I’ve seen of late. And believe me, I see a LOT of tube maps.

It’s so weird, in fact, that it’s weird in two distinct ways. Firstly it’s geographically accurate: rather than adopting the Harry Beck-style diagram we all know and love, it uses a map of the London boroughs to show where the lines actually go.

Secondly, it shows just four lines: the Metropolitan, Hammersmith & City, Circle and District. Effectively, it’s the lines which share track with the inner circle.

What’s really weird about it, in its way, is that it’s actually the work of Transport for London (TfL), rather than a bunch of nerds like, well, like me.

Click to expand. Image: TfL.

There is a method to this madness. Not all tube lines are actually tube lines: technically, that label should only apply to those which run through tunnels bored deep underground.

These others are technically “sub-surface” lines. They’re the oldest part of the network, built through the relatively primitive method of digging trenches, sticking tracks in them and then building over the top again. These have slightly bigger trains and, generally, better air-conditioning, too.

I’m not sure why TfL felt moved to produce this as a separate map. Perhaps it’s a useful aide-memoire for those working on the network. Perhaps it’s to show which stations are reachable directly via lines serving the inner circle, for some reason. Or perhaps it’s just because they know that someone like me would inevitably write about it, and they like the attention. Who can say?

One thing we can say, though, is that there is a weirdly long gap between Kings Cross St. Pancras and Farringdon, and they should build a station at Mount Pleasant to plug it.

You can see the whole thing here. Hat tip: Diamond Geezer.

UPDATE: Okay, guys, I’m going to level with you: I wrote the above, very quickly, on Friday afternoon in about three minutes because I thought there might be traffic in it. (Don’t judge me, you clicked, didn’t you?) I may not have dedicated quite the investigative energies to this story that a matter of such importance clearly deserves.

Anyway. Diamond Geezer has been in touch to point out that TfL have actually explained why the map exists. It’s to show the scope of this project:

We are transforming the Circle, District, Hammersmith & City and Metropolitan lines. When the work is completed in 2023, increased capacity and boosted reliability will make journeys faster and more comfortable.

Because these lines share a lot of track and infrastructure, they are being modernised under a single combined and integrated project, Four Lines Modernisation (4LM).

The 4LM project will involve new trains, tracks and signalling, allowing shorter journey times a 33 per cent increase in peak-hour capacity on the sub-surface network. Which, since it makes up 40 per cent of the network, is a pretty big deal.

Cool.

Jonn Elledge is the editor of CityMetric. He is on Twitter as @jonnelledge and also has a Facebook page now for some reason. 

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