Warning: this is not going to be interesting for anyone but people interested in trains underground. There's one more thing about the Tube I wanted to comment on, this time specifically about Northern Line.

In this funny video https://www.youtube.com/watch?v=P4e-Al90tSs Central says that Northern is 'literally two different people'. And that is actually true.

When they made Northern, they merged two lines. One of them had narrower tunnels than the other one, so had to be widened when the lines were merged.

Now, we are left with a line which starts at Morden (southern-most Tube terminus), splits at Kennington to go via Charing Cross or via Bank, and then both rejoins and diverges at Camden Town, to go to Edgware or High Barnet (or sometimes to Mill Hill East).

And guess what. As probably each and every line in the world which splits, Northern is a huge pain in the ass for TfL.

I've heard stories about Line 13 in Paris - the light blue line which splits in a station called La Fourche (Fork) and goes to two different difficult suburbs, Clichy and St Denis. Well this direction (from the city centre to Clichy / St Denic) is not the main problem. The other one is. It's because the trains are supposed to meet at La Fourche and go alternately, one arrives from Clichy and goes to the city centre, then one from St Denis, then one from Clichy, etc. etc.

The problem is that it's not this smooth. Both suburbs are densely populated and not exactly rich. So problems happen. Every day. And trains get delayed as a result. Meaning that every time one half of the line gets stuck, the other one also gets stuck, because they are supposed to wait for the other train.

Same story apparently goes with Northern. But Northern is even more funny because it has Kennington and it has Camden Town, so there are two stations where the trains part. In Camden Town, if you want to change for a train going to the other branch than the train you are in, it's not that easy, you have to walk somewhere etc.

So what TfL did is that most of the trains go from Morden to alternate termini via the Bank branch. There are only few trains per hour to the Charing X branch.

Also, there apparently were plans to split Northern into two lines. But that would require rebuilding Camden Town, and for many reasons, this is not feasible.

The fun continues.