In article ,
CharlesPottins writes
I thought the reason underground tube lines were less common south of the river
was the number of underground streams?

No. Three main reasons:

(1) The Blue Clay is not such a convenient layer south of the river,
though it does exist (see the Northern Line as an example).

(2) The various surface railways south of the river were much more
interested in competing for local traffic compared with those to the
north.

(3) Parliament created a "no-go zone" for surface railways; this covered
roughly the area inside the present Circle Line. While there were
exceptions - termini for routes extended over the river, and of course
Thameslink - to a large extent it left a region for the tubes to develop
with no effective competition.

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Clive D.W. Feather | Home:
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