In message , at 23:04:32 on Fri, 15 Nov
2019, Bryan Morris remarked:
In message , Bryan Morris
writes
In message , Roland Perry
writes
In message , at 20:41:41 on Fri, 15 Nov
2019, remarked:
On Fri, 15 Nov 2019 15:17:03 +0000
Roland Perry wrote:
In message , at 14:24:18 on Fri, 15 Nov
2019, Bryan Morris remarked:

I find the Picc unbearably deep, so by the time I've reached Barons
Court (westbound) I'm standing by the door gasping for fresh air. No
other tunnel affects me like that, not even the Chunnel.

I thought the Northern Line Edgware Branch was deepest. I know when I
used to travel via Hampstead/Golders Green my ears used to pop.

That's the deepest under the surface, but the surface is a hill! Air
pressure on the surface there will be lower as a result, by about 2.5%

I think the deepest below sea level (from memory) is the Jubilee between
Westminster and Waterloo.

Later: Hampstead Station is approx 200m above sea level at the surface,
140m above sea level at the platform.

Not it isn't. The highest point of the heath which is well above the tube
station is 134m. I'm guessing the station entrance is around 80-90m.

That's what one gets for looking things up at what turns out to be an
unreliable source. I still believe that the platforms are 60m below
the surface, which a more reliable source puts at 376ft (ie 115m).

Hampstead is on a steep hill and the station platforms are the deepest
on the London Underground network, at 58.5 metres (192 ft) below
ground level. It has the deepest lift shaft on the Underground at 55
metres (180 ft) which houses high-speed lifts.
Source https://en.wikipedia.org/wiki/Hampstead_tube_station

BTW - I used to live in Highgate and frequently travelled Hampstead
Lane/Heath Street to my office . Hampstead station is not at the top of
the Hill (I might be wrong but it's the Pond by the Heath that's
probably the apex) so the line is further under ground there than at
the station.

The highest point the line passes under is 446ft (136m) the other side
of the road from the aptly named Heath Brow car park; the old Bull and
Bush pub is 391ft (119m).

Note that Google maps is particularly bad at showing the route with it's
"fit a curve to the stations" algorithm ignoring a bend just north of
Hampstead station with the actual line following Heath Road.
--
Roland Perry