CJB wrote on 18 May 2009 21:26:08 ...

How are folks intending that Crossrail services and all the various
extensions to the route suggested above be pathed into the FGW
mainline between Maidenhead and Paddington? Right now the mainline is
full. HEX comes off the Airport Branch into the paths of FGW HST
services.

Not exactly. It is allocated paths *between* the HST services.

Connect is even more conflicting in that it has to cross the
main lines to obtain access to the local lines.

Not true. There is currently a link between the HEx Up ramp and the GWR
Down Relief which is used by Connect in both directions. This involves
down Connect trains using a crossover on BAA territory to move on to the
down line into the airport, and up Connect trains using a down-to-up
crossover between the relief lines west of Hayes. So there are various
conflicts, but they don't affect the main (fast) lines.

Crossrail will replace Connect (currently 2tph) by a 4 tph service to
the airport. Airport Junction will be reconstructed to enable trains to
run in either direction between the airport and the main or relief lines
without any conflict with other lines. Crossrail trains to Maidenhead
will replace some of the existing relief line services.

Remember that out of the 24 tph westbound in the peaks through the
Crossrail tunnels to Paddington, 14 tph will terminate at
Paddington/Westbourne Park sidings, leaving only 10 tph to run down the
relief lines. So about 50% capacity if they get the signalling up to
scratch.

--
Richard J.
(to email me, swap 'uk' and 'yon' in address)