Clive D. W. Feather wrote:

Northbound trains would have to cross the other three running lines to
reach the ELL alignment. That direction is going to require a new
flyover.

Correct. At the Infrarail O5 RCEA seminar in Manchester last week
Parsons Brinkerhof, the project managers for ELL briefed on the project
status. Major works on the phase 1 line include turn back facilities at
West Croydon, restoration of the bay(s) at Crystal Palace - (some
ongoing discusion concerning restoration of the ticket hall0,
construction of a grade separated junction north of New Cross Gate
linking the LBSCR up slow to the north bound ELL - possibly beginning
on the old carriage road alignment. Extensive stabling north of New
Cross Gate - New Cross LUL depot to close. Resignalling to Network Rail
standards and slab track installation on the old ELL. North of
Whitechapel a 1 in 30 gradient over a Warren truss girder bridge at
GE19 just east of Liverpool Street. This will be installed during an 8
day Christmas Blockade of Liverpool Street. Shades of the City
Thameslink - Blackfriars ski jump ramp. Crossing Bishopsgate goods yard
on to the North London arches to Dalston. Taylor Woodrow are
refurbishing the arches.Bridges have been removed and bridge bash
barriers installed to stop heavy goods vehicles and buses using side
roads that will eventually have new rail bridges installed. Some
ongoing debate about who will own the infrastructure Network Rail or
TfL - HMRI may well have views on split ownership of the line. Phase 2
timing not yet finalised but probably after Olympics as Crystal Palace
is IIRC an Olympic venue.

regards
Bob