Hmm, guess it depends on which track is used... lots of varying grades north of Gasworks Tunnel and Copenhagen Fields... [where the NLL and CTRL cross over]
Hmm...
Why I was asking was because I am trying to sort out the Beck Line
at Finsbury Park... Subbrit's railway Site indicates a disused platform on the Western Side of Finsbury Park...
The Beck line (as currently planned) comes into Finsbury
Park from Nags head.. Trying to place the Beck Line
in Tube at Finsbury Park, but at the level of the closed platform at Stroud Green given gradients is a non starter...
Thusly the current plan is to surface it under Nags Head,
and bring it into Finsbury Park on a viaduct, with the current
down Goods realigned, and the Beck Line Platforms at Finsbury Park
being roughly level with the positon of the abandoned platform on
the western side of the station...
From here the Beck Line would effectivly continue on
viaduct/embankment upto the level of the Parkland Walk
alignment... My 1914 map shows that there was originally
a link between the Down lines at Finsbury Park(as opposed to the
links on the UP side which are more well known..), and it was intended that the Beck Line, lie to the West of this...
However, In order to accurately determine the positionings for the Beck Line, as well as clearance required under 2 new bridges at
Finsbury Park. I was needing the gradient data of the current ECML, in order to have reference points..
North of Finsbury Park, the orignal GNR Edgware branch had a bridge over the ECML mainline. Long since replaced by a footbridge,
it's height is nonthless indcative of the position the Parkland walk
alignment is immediately before crossing the ECML..
The notes I have on loading gauges seem to indicate mainline
works need at least 5m headroom, If not more-given OHLE,
a figure I can't currently reconcile with known data about the
GNR branch..
Assuming Finsbury Park station isn't on a gradient of more than
1 in 500 (HMRI requirment on platforms) it's possible to put the
Beck Line on a gentle 1/70 steepening into 1/50 down from
Storud Green to Finsbury park, and thence on a 1/50 down
towards Nags Head...
I did want to try and be reasonably accurate in getting
the correct bridge heights
Whilst I do have a rough estimate for the gradient of the original
spur from the Dn lines to the Highate line, It's gradient is a bit sharp, and hence the slope of the Beck Line may be somewhat softened..
