Nottingham59
Established Member
For what it's worth, HS2 generally transitions from embankment to viaduct at between 6m and 10m above ground level. If you only need 7m rail-to-rail height distance, then the economic structure is likely to be embankment (unless there is no space for it) or when actually crossing other infrastructure.How much of that 800 metres would be earthworks, and how much concrete viaduct, in a grade separation on "normal" terrain? How would that be different on a Fenland peat bog with unstable ground conditions?
HS2 standard slope is 1 in 2.5, implying a total width of around 25m for a 7m high embankment supporting a double track aligment.
If you're interested in the ground conditions around Ely, the BGS borehole archive is viewable here:
EDIT:
Many of the deeper boreholes in the vicinity of Ely North junction show soft weathered clays down to around 10-15m, lying on stronger clays and mudstones below that. I don't know what that means for depth of piles that would be required.
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