[SideburnsOfDoom]

> London always seems to have a redundancy in the case of a line being unusable.

The London underground is indeed a redundant spiderweb. But the article focuses more on mainline trains, which are much more constrained.

The only way right through central London for these trains was north-to-south, the Snow Hill tunnel: Kings Cross -> Farringdon -> City Thameslink -> Blackfriars -> South of the river. This can only be a bottleneck.

But now there is the Elizabeth line east-to-west as well.