Neil Williams wrote:
On Fri, 23 Nov 2007 20:26:59 GMT, "Richard J."
wrote:

It was an example of a station with surface-level platforms so far
above sea level that that being on the "Underground" is arguably
more bizarre than Brighton being similarly branded.

In Hamburg, there is a section (Roedingsmarkt-Rathaus, roughly) where
the U-bahn is elevated about 5m above the ground, and the S-Bahn is
underground...

AFIAK, U-bahns are controlled by the city government and S-bahns are
controlled by the federal government, and there is no particular reason why
an entire U-line couldn't be overground or an entire S-line be underground,
although the latter is particularly unlikely.

At Stratford station the Overground platforms are downstairs from the
Underground platforms.