Mobius Tube

The Northern Line switches from right-hand to left-hand lanes, halfway through. How is this physically possible?

Here’s the conundrum I am grappling with today, concerning the Northern Line on the London Underground.

When you embark at London Bridge, the Northbound and Southbound lines are arranged in what I would describe as the Continental style.  That is, to the right of each other.  It is the left set of doors that open.  However, when you disembark at Angel, the two lines are arranged in the Commonwealth style.  That is, they are to the left of each other.

How is this possible?  It must mean that the two lines twist around one another, like a double-helix.  Either that, or we have some sort of Subway Named Mobius beneath London.  Can anyone explain the peculiar engineering or physical geography that causes this to be the case?

I wonder, do maps of the actual underground network exist anywhere online?  Not the Harry Beck maps, or its Google representation but a accurate scematic of the actual tracks, junctions and stations.  I fancy it might be quite a fascinating labyrinth.

Underground Ad Space
Underground Ad Space. I only use this image 'cause I haven't taken one of the actual tube trains yet.

Update

A rollercoaster that’s a mobius strip.

Another Update

Eurostar enters the fourth dimension?

Every day thousands of travellers take the Eurostar to a strange and foreign land. No, not Paris; the Fourth Dimension. Although many visitors to Paris don’t realise it, at the heart of the city is a portal to hyperspace. As you emerge from the Paris subway into the financial district at La Défense you are greeted by a huge four-dimensional cube.

6 thoughts on “Mobius Tube”

  1. Yes, this happens at various points on the system. I have often wondered about it, but not being very good at maths or spatial reasoning, the only explanation that I have thought of is to work in three dimensions. That is to say that the crossing-over occurs where one line goes above the other, for evolutionary, geophysical or other reasons.

    Obviously, both directions have to be at the same vertical level in stations (except for eg the central line at Notting Hill, where they are not), but outside of stations, anything is possible.

    Another more simpler explanation that occurs to me could be that the lines actually touch eachother, ie they share a portion of the track, which is controlled by points. In this case, the cross-over is fairly straight-forward, even if the control of train-traffic at that section is a logisitical nightmare.

    Then there are the fourth and fifth dimensions of tube travel, but that is another story altogether.

  2. I found myself thinking about the same sort of thing a couple of months ago, only about the crossover between Shepherd’s Bush and White City. These sites seemed to cover that in a bit more detail…

    http://www.trainweb.org/tubeprune/Woodlane%20whitecity.htm
    and http://underground-history.co.uk/front.php

    seems mostly that they crossover either because the track had junctions that forced it to run under or over the track they now use, allow for easier cornering, or to avoid tunnelling through something they don’t want or can’t go through.

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